Research Studies

Decreased Spasticity & Contractures/ Preventing Loss of Range of Motion

Tilt table standing for reducing spasticity after spinal cord injury.

Arch Physical Medicine Rehabilitation. 1993 Oct;74(10):1121-2.
Bohannon RW.
Department of Rehabilitation, Hartford Hospital, CT.

A patient with a T12 spinal cord injury and intractable extensor spasms of the lower extremities participated in tilt table standing trial on 5 nonconsecutive days to determine if the intervention would affect his spasticity and spasms. Each day's standing trial was followed by an immediate reduction in lower extremity spasticity (measured using the modified Ashworth scale and pendulum testing). Standing was also accompanied by a reduction in spasms that lasted until the following morning. The reduction of spasms was particularly advantageous to the performance of car transfers. Tilt table standing merits further examination as a physical treatment of spasms that accompany central nervous system lesions.

For the complete document, please visit www.pubmed.com or your local medical library.
PMID: 8215868 [PubMed - indexed for MEDLINE]

Effects of prolonged muscle stretch on reflex and voluntary muscle activations in children with spastic cerebral palsy.

Scand J Rehabilitation Medicine. 1990;22(4):171-80.
Tremblay F, Malouin F, Richards CL, Dumas F.
Neurobiology Laboratory, Faculty of Medicine, Laval University, Quebec, Canada.

We studied the short term effects of a single session of prolonged muscle stretch (PMS) on reflex and voluntary muscle activations in 22 children with spastic cerebral palsy (CP) assigned to an experimental (n = 12) and a control group (n = 10). Children of the experimental group underwent PMS of the triceps surae (TS) by standing with the feet dorsiflexed on a tilt-table for 30 min, whereas children of the control group were kept at rest. The effects were determined by measuring the associated changes in torque and in electromyographic (EMG) activity of the TS and tibialis anterior (TA) muscles during both passive ankle movements and maximal static voluntary contractions. The results indicate that PMS led to reduced spasticity in ankle muscles as demonstrated by the significant reductions (p less than 0.05) of the neuromuscular responses (torque and EMG) to passive movement. These inhibitory effects lasted up to 35 min after cessation of PMS. In addition, the capacity to voluntarily activate the plantar flexors was significantly (p less than 0.05) increased post-PMS, but the capacity to activate the dorsiflexors was apparently not affected. These findings suggest that repeated sessions of PMS may have beneficial effects in the management of spasticity in children with CP.

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PMID: 2263918 [PubMed - indexed for MEDLINE]

Evaluation of the effects of muscle stretch and weight load in patients with spastic paraplegia.

Scand J Rehabilitation Medicine. 1981;13(4):117-21.
Odeen I, Knutsson E.

Clinical observations on patients with spastic paraplegia have indicated that a training regime including weight load on the lower limbs may reduce the muscular hypertonus. Due to the spontaneous fluctuations and great variability in muscle tone it is difficult to judge from clinical findings how the effects may be related to muscle stretch and weight load. Therefore, quantitative determination of the effects on muscle tone by stretch and loading was made in 9 paraplegic patients. Muscle tone was measured before and after 30 min of stretch or weight load in 8 sessions on 4 consecutive days. Stretch was obtained by bracing the foot in maximal dorsal flexion with patient in supine position. For weight load on the lower limbs, the patient stood on a tilt-table at an angle of 85 degrees with feet in 15 degrees dorsal or plantar flexion. Resistance to passive movements was determined during a series of sinusoidal ankle joint movements at three different speeds. After weight load in standing with the feet in dorsal or plantar flexion, the average reduction was 32 and 26%, respectively. After stretch in supine, the average reduction was 17%. Thus, the three procedures tested all resulted in reduction of muscle tone. The largest reductions were obtained by weight load with stretch imposed upon the calf muscles.

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PMID: 7347432 [PubMed - indexed for MEDLINE]

Reduction of muscular hypertonus by long-term muscle stretch.

Scand J Rehabilitation Medicine. 1981;13(2-3):93-9.
Odeen I.

In 10 patients with spastic paraparesis, the effect of long-term stretch on hip adductor muscle tone was studied. Stretch was accomplished by using a mechanical leg-abductor device giving individually adjusted adductor muscle stretch in single or repeated 30 min periods. The effect on muscle tone was estimated from surface EMG activity and by range of voluntary and passive hip abduction. The passive movements were obtained by an individually adjusted constant pulling force. After a single session of stretch, range of voluntary hip abduction increased 3 to 16 degrees (average 85%). Range of passive movement increased 1 to 9 degrees (average 23%). After repeated stretch periods in a home program (4 patients), range of voluntary hip abduction increased 5 to 22 degrees (average 255%). Range of passive movements increased 6 to 12 degrees (average 48%). In all patients studied the co-activation of the antagonists in voluntary hip abduction was reduced after a stretch session.

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PMID: 7345572 [PubMed - indexed for MEDLINE]

Effects of a single session of prolonged muscle stretch on spastic muscle of stroke patients.

Proc Natl SCI Counc Repub China B. 2001 Apr;25(2):76-81.
Tsai KH, Yeh CY, Chang HY, Chen JJ.
Department of Industrial Management, Southern Taiwan University of Technology, Tainan, ROC.

The control of spasticity is often a significant problem in the management of patients with spasticity. The aim of this study was to evaluate the effect of a single session of prolonged muscle stretch (PMS) on the spastic muscle. Seventeen patients with spastic hemiplegia were selected to receive treatment. Subjects underwent PMS of the triceps surae (TS) by standing with the feet dorsiflexed on a tilt-table for 30 minutes. Our test battery consisted of four measurements including the modified Ashworth scale of the TS, the passive range of motion (ROM) of ankle dorsiflexion, the H/M ratio of the TS, and the F/M ratio of the tibialis anterior (TA). The results indicated that the passive ROM of ankle dorsiflexion increased significantly (p < 0.05) compared to that before PMS treatment. Additionally, PMS reduced motor neuron excitability of the TS and significantly increased that of the TA (p < 0.05). These results suggest that 30 minutes of PMS is effective in reducing motor neuron excitability of the TS in spastic hemiplegia, thus providing a safe and economical method for treating stroke patients.

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PMID: 11370763 [PubMed - indexed for MEDLINE]

Osteogenesis imperfecta: rehabilitation approach with infants and young children.
Arch Phys Med Rehabilitation. 1984 Sep;65(9):537-41.
Binder H, Hawks L, Graybill G, Gerber NL, Weintrob JC.

A rehabilitation approach, consisting of initial handling and positioning followed by functional and formal strengthening exercises, was developed for the child with severe progressive osteogenesis imperfecta (OI). The program was developed because of the increased life expectancy for infants and children with severe progressive OI, combined with the lack of published reports dealing with their rehabilitation. The program can be followed easily by parents or therapists with regular monitoring by a psychiatrist. The goals are to improve the life span as well as the quality of life of these children by preventing the following: (1) positional contractures and deformities, (2) muscle weakness and osteoporosis, and (3) malalignment of the lower extremity joints prohibiting weight-bearing. Implementation of the program requires full cooperation of the parents. The initial results in four children between the ages of 3 and 11 years are encouraging. The benefits of increased strength and mobility leading to more age-appropriate activities and behaviors outweigh the only observed negative result, that is trauma-related lower extremity fractures in children with milder disease, and therefore greater mobility and higher activity levels.

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PMID: 6477088 [PubMed - indexed for MEDLINE]

Nonoperative treatment of osteogenesis imperfecta: orthotic and mobility management.
Clin Orthop Relat Res. 1981 Sep;(159):111-22.
Bleck EE.

The problem of osteoporosis superimposed on the basic collagen defect of osteogenesis imperfecta has been approached by the use of plastic containment orthoses for the lower limbs, in addition to developmentally staged mobility devices that assist early standing and walking. The purpose of forcing early weight-bearing is to provide stress to the lower limb bones in order to minimize osteoporosis, prevent refracture and deformity, and curb subsequent immobilization osteoporosis, thus breaking a vicious cycle. Management goals are based upon adult needs for independence: efficiency in daily living activities and in mobility. These goals were reached in most of our patients via use of plastic orthoses, early weight-bearing, and electrically powered wheelchairs. Manual osteoclasis of the tibia followed by plastic orthoses utilizing principles of fluid compression to support fractured or structurally weak bones appeared successful at the time of follow-up. Intramedullary rodding of the femur was necessary in most of the 12 children with osteogenesis imperfecta congenita. Supplementary plastic orthoses have reduced the refracture rate in both the tibia and the femur. Social integration of the children was reflected by the fact that among the 12 OI congenita cases, ten were attending regular educational institutions. Twelve OI tarda children fared well, all attaining complete independence in daily living, mobility and ambulation. Seven of this group were treated with intramedullary rodding of the femur or tibia and with plastic orthoses. Five patients required no treatment.

For the complete document, please visit www.pubmed.com or your local medical library.
PMID: 7285447 [PubMed - indexed for MEDLINE]

Reliability and comparison of weight-bearing ability during standing tasks for individuals with chronic stroke.
Arch Phys Med Rehabilitation. 2002 Aug;83(8):1138-44.
Eng JJ, Chu KS.
School of Rehabilitation Sciences, University of British Columbia, Vancouver, BC, Canada. Janicee@interchange.ubc.ca

OBJECTIVES: To determine the test-retest reliability over 2 separate days for weight-bearing ability during standing tasks in individuals with chronic stroke and to compare the weight-bearing ability among 5 standing tasks for the paretic and nonparetic limbs. DESIGN: Prospective study using a convenient sample. SETTING: Free-standing tertiary rehabilitation center. PARTICIPANTS: Fifteen community-dwelling stroke individuals with moderate motor deficits; volunteer sample. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Weight-bearing ability as measured by the vertical ground reaction force during 5 standing tasks (rising from a chair, quiet standing, weight-shifting forward, backward, laterally). RESULTS: The weight-bearing ability was less for the paretic limb compared with the nonparetic limb, but the intraclass correlation coefficients were high (.95-.99) for both limbs between the 2 sessions for all 5 tasks. The forward weight-shifting ability was particularly low in magnitude on the paretic side compared with the other weight-shifting tasks. In addition, the forward weight-shift ability of the nonparetic limb was also impaired but to a lesser extent. Large asymmetry was evident when rising from a chair, with the paretic limb bearing a mean 296N and the nonparetic side bearing a mean 458N. The weight-bearing ability during all 5 tasks correlated with one another (r range,.56-.94). CONCLUSIONS: Weight-bearing ability can be reliably measured and may serve as a useful outcome measure in individuals with stroke. We suggest that impairments of the hemiparetic side during forward weight shifting and sit-to-stand tasks presents a challenge to the motor systems of individuals with stroke, which may account for the poor balance that is often observed in these individuals. Copyright 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.

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PMID: 12161837 [PubMed - indexed for MEDLINE]

Contractures secondary to immobility: is the restriction articular or muscular? An experimental longitudinal study in the rat knee.
Arch Phys Med Rehabilitation. 2000 Jan;81(1):6-13.
Trudel G, Uhthoff HK.
Department of Medicine, University of Ottawa, Canada.

OBJECTIVES: To measure articular structures' contribution to the limitation of range of motion after joint immobility. STUDY DESIGN: Experimental, controlled study involving 40 adult rats that had one knee joint immobilized in flexion for durations of 2, 4, 8, 16, and 32 weeks; 20 rats underwent a sham procedure. The angular displacement was measured both in flexion and extension at three different torques. Myotomy of transarticular muscles allowed isolation of the arthrogenic component of the contracture. RESULTS: A contracture developed in all immobilized knees. The articular structures were incrementally responsible for the limitation in range of motion (from 12.6 degrees +/-6.7 degrees at 2 weeks to 51.4 degrees +/-5.4 degrees at 32 weeks). The myogenic restriction proportionately decreased over time (from 20.1 degrees +/-8.4 degrees at 2 weeks to only 0.8 degrees +/-7.2 degrees at 32 weeks). The increase in the arthrogenic component of contracture was predominant in extension. CONCLUSION: This study quantified the increasing role of arthrogenic changes in limiting the range of motion of joints after immobility, especially as the period of immobility extended past 2 weeks. These data provide a better understanding of joint contracture development and can be used to guide therapeutic approaches.

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PMID: 10638868 [PubMed - indexed for MEDLINE]

Extent and direction of joint motion limitation after prolonged immobility: an experimental study in the rat.
Arch Phys Med Rehabilitation. 1999 Dec;80(12):1542-7.
Trudel G, Uhthoff HK, Brown M.
Department of Medicine, University of Ottawa, and the Institute for Rehabilitation Research and Development, Ontario, Canada.

OBJECTIVES: To test the hypotheses that contractures progress at different rates in relation to the time after immobilization, that immobilization in flexion leads to loss of extension range of motion, and that joints of sham-operated animals are better controls than the contralateral joint of experimental animals. STUDY DESIGN: Experimental, controlled study in which 40 adult rats had one knee joint immobilized at 135 degrees of flexion for up to 32 weeks and 20 animals underwent a sham procedure. At intervals of 2, 4, 8, 16, and 32 weeks, 8 experimental and 4 sham-operated animals were killed and their knee motion measured in flexion and extension. RESULTS: In the experimental group, the range of motion decreased in the first 16 weeks of immobility at an average rate of 3.8 degrees per week (p<.0001) to reach 61.1 degrees of restriction. A plateau was then observed from which the contracture did not progress further. The loss in range of motion occurred in extension, not in flexion. CONCLUSION: This study defined an acute stage of contractures starting at the onset of immobility and lasting 16 weeks, during which the range of motion was progressively restricted, and a chronic stage during which no additional limitation was detected. The loss in motion was attributed to posterior knee structures not under tension during immobilization in flexion. Contrary to the hypothesis, the contralateral joint was validated as a control choice for range-of-motion experiments.

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PMID: 10597804 [PubMed - indexed for MEDLINE]

Improved Digestive System (bowel & bladder)

Case study to evaluate a standing table for managing constipation.

SCI Nurse 2001 Summer;18(2):74-7.
Hoenig H, Murphy T, Galbraith J, Zolkewitz M.
Duke University Medical Center, Durham, North Carolina, USA.

Standing devices have been advocated as a potentially beneficial treatment for constipation in persons with spinal cord injury (SCI); however, definitive data are lacking. A case of a patient who requested a standing table to treat chronic constipation is presented as an illustration of a method to address this problem on an individual patient level. The patient was a 62-year-old male with T12-L1 ASIA B paraplegia who was injured in 1965. The patient was on chronic narcotics for severe, nonoperable shoulder pain. His bowel program had been inadequate to prevent impactions. A systematic approach was used to measure the effects of a standing table on frequency of bowel movements (BMs) and on length of bowel care episodes. There was a significant (p < 0.05) increase in frequency of BMs and a decrease in bowel care time with the use of the standing table 5 times/week versus baseline. For this patient, the use of the standing table was a clinically useful addition to his bowel care program.

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PMID: 12035465 [PubMed - indexed for MEDLINE]

Prevention of Pressure Ulcers

Long-term medical complications after traumatic spinal cord injury: a regional model systems analysis.

Arch Phys Med Rehabilitation. 1999 Nov;80(11):1402-10.
McKinley WO, Jackson AB, Cardenas DD, DeVivo MJ.
Department of Physical Medicine & Rehabilitation, Medical College of Virginia/Virginia Commonwealth University, Richmond 23298, USA.

OBJECTIVE: To analyze the incidence, risk factors, and trends of long-term secondary medical complications in individuals with traumatic spinal cord injury. DESIGN: Data were reviewed from the National SCI Statistical Center on annual evaluations performed at 1, 2, 5, 10, 15, and 20 years after injury on patients injured between 1973 and 1998. SETTING: Multicenter Regional SCI Model Systems. MAIN OUTCOME MEASURES: Secondary medical complications at annual follow-up years, including pneumonia/atelectasis, autonomic dysreflexia, deep venous thrombosis, pulmonary embolism, pressure ulcers, fractures, and renal calculi. RESULTS: Pressure ulcers were the most frequent secondary medical complications in all years, and individuals at significant (p < .05) risk included those with complete injuries (years 1, 2, 5, 10), younger age (year 2), concomitant pneumonia/atelectasis (year 1, 2, 5), and violent injury (years 1, 2, 5, 10). The incidence of pneumonia/atelectasis was 3.4% between rehabilitation discharge and year-1 follow-up with those most significantly at risk being older than 60 years (years 1, 2, 5, 10) and tetraplegia-complete (years 1, 2). One-year incidence of deep venous thrombosis was 2.1% with a significant decline seen at year 2 (1.2%), and individuals most significantly (p < .001) at risk were those with complete injuries (year 1). The incidence of calculi (kidney and/or ureter) was 1.5% at 1-year follow-up and 1.9% at 5 years and was more frequent in patients with complete tetraplegia. Intermittent catheterization was the most common method of bladder management among patients with paraplegia but became less common at later postinjury visits. CONCLUSIONS: Pressure ulcers, autonomic dysreflexia, and pneumonia/atelectasis were the most common long-term secondary medical complications found at annual follow-ups. Risk factors included complete injury, tetraplegia, older age, concomitant illness, and violent injury.

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PMID: 10569434 [PubMed - indexed for MEDLINE]

Help Maintain Bone Density & Lessen Progressive Scoliosis

Can Using Standers Increase Bone Density In Non-Ambulatory Children?
Danielle A. Katz, MD, Brian Snyder, MD, PhD, Anton Dodek, MD, Ingrid Holm, MD Claire Miller, BS (Children’s Hospital, Harvard Medical School, Boston, Massachusetts)

Abstract as published in the American Academy of Cerebral Palsy and Developmental Medicine (AACPDM) 2006 Conference Proceedings

Purpose: Pathologic fractures are a significant source of morbidity for non-ambulatory children with neuromuscular dysfunction.  We hypothesize that increasing weight-bearing in non-ambulatory children will increase bone material density (BMD) and decrease fracture risk.  The aim of this pilot study was to demonstrate that non-ambulatory children participating in a standing program for at least two hours a day will experience an increase in BMD in the weight bearing bones.  We also evaluate the reliability of measuring BMD at the calcaneous (weight bearing bones) and distal forearm (non-weight bearing bone) using peripheral DXA in delayed, non-ambulatory children.

Methods: After receiving IRB approval, 12 non-ambulatory, quadriplegic children (ages 12-21) consented to participate in a 2 hour/day, 5 day/week standing program.  A history, orthopaedic exam, determination of bone age, laboratory tests for metabolic bone disease and BMD at the calcaneal tuberosity and distal forearm metaphyses were obtained.  Compliance with the prescribed standing program was monitored for 6 months.  BMD was measured using peripheral DXA at baseline and every 3 months.  Using Jan. 2003 BMD data as a baseline, the ratio of change in BMD at the calcaneous and distal forearm was evaluated as a function of percent compliance with standing program.

Results: Intrarater reliability for BMD measured by peripheral DXA was good: Pearson correlation for the calcaneous = 0.90 (p=0.01) and for the forearm = 0.96 (p=0.01).  Paired t test between two sets of data measured at each site on the same day were not different for calcaneous (t=0.92, df=15, p=0.37) or forearm (t=0.05, df=15, p=0.96).  Compliance with the standing program was inconsistent.  No patients were 100% compliant.  Patients tended to stand longer at the initiation of the study Jan.-April (Jan vs Apr, p = 0.018; Jan vs Jul, p = 0.89; Apr vs Jul, p = 0.063).  Compliance (%) was positively correlated (r = -0.62) with increased calcaneous BMD measured in April.  This is in contrast to forearm BMD measured at the same time; which was negatively correlated (r = -0.44) with standing compliance.  This support the notion that standing preferentially increases bone mass in the weight-bearing bones.  However the BMD at the calcaneous measured in July was decreased, perhaps reflecting the decreased compliance the with standing program over the succeeding interval April-July.

Conclusion: It is feasible to have non-ambulatory children participate in a rigorous standing program.  The weight bearing “dose” affects BMD at the calcaneous but the benefit appears to be transient if the intensive standing program is not sustained.

Significance: The intensive use of standers (10 hours/wk) may have a beneficial effect on BMD of weight bearing bones in non-ambulatory children.

Bone measurements by peripheral quantitative computed tomography (pQCT) in children with cerebral palsy
J Pediatr. 2005 Dec;147(6):791-6.
Binkley T, Johnson J, Vogel L, Kecskemethy H, Henderson R, Specker B.
Ethel Austin Martin Human Nutrition Program, South Dakota State University, Brookings, South Dakota 57007, USA.

Longitudinal changes in bone density in children and adolescents with moderate to severe cerebral palsy.J Pediatr. 2005 Jun;146(6):769-75.
Henderson RC, Kairalla JA, Barrington JW, Abbas A, Stevenson RD.
Department of Orthopaedics and Biostatistics, University of North Carolina, NC 27599, USA. rchh@med.unc.edu

OBJECTIVE: To assess the natural history of "growth" in bone mineral density (BMD) in children and adolescents with moderate to severe cerebral palsy (CP). STUDY DESIGN: A prospective, longitudinal, observational study of BMD in 69 subjects with moderate to severe spastic CP ages 2.0 to 17.7 years. Fifty-five subjects were observed for more than 2 years and 40 subjects for more than 3 years. Each evaluation also included assessments of growth, nutritional status, Tanner stage, general health, and various clinical features of CP. RESULTS: Lower BMD z-scores at the initial evaluation were associated with greater severity of CP as judged by gross motor function and feeding difficulty, and with poorer growth and nutrition as judged by weight z-scores. BMD increased an average of 2% to 5%/y in the distal femur and lumbar spine, but ranged widely from +42%/y to -31%. In spite of increases in BMD, distal femur BMD z-scores decrease with age in this population. CONCLUSIONS: Children with severe CP develop over the course of their lives clinically significant osteopenia. Unlike elderly adults, this is not primarily from true losses in bone mineral, but from a rate of growth in bone mineral that is diminished relative to healthy children. The efficacy of interventions to increase BMD can truly be assessed only with a clear understanding of the expected changes in BMD without intervention.

Bone mineral density in children with cerebral palsy.
Pediatr Int. 2001 Apr;43(2):157-60. Tasdemir HA, Buyukavci M, Akcay F, Polat P, Yildiran A, Karakelleoglu C.
Department of Pediatric Neurology, Atatürk University Faculty of Medicine, Erzurum, Turkey.

BACKGROUND: The purpose of the present study was to evaluate the severity of and factors related to osteopenia in children with cerebral palsy (CP). METHODS: Bone mineral density (BMD), calcium (Ca), phosphate (P), alkaline phosphatase (ALP), creatinine, parathyroid hormone (PTH) and 25-hydroxy vitamin D3 (25OHD3) concentrations were determined in 24 children with CP (15 ambulant, nine non-ambulant), aged between 10 months and 12 years (mean (+/-SD) 4.1+/-2.9 years). These vaules were compared with data obtained from a control group. RESULTS: Adjusted mean BMD values were lower in the patient group than in controls (P<0.05). However, there was no difference between BMD values of ambulant and non-ambulant patients. The Ca and P levels of the patient group were significantly higher than those of controls (P<0.05). CONCLUSIONS: The present study showed that BMD was decreased in all children with CP, but to a greater extent in non-ambulant children with CP, and immobilization is the major effective factor on bone mineralization.

Osteoporosis after spinal cord injury.
J Orthop Res. 1992 May;10(3):371-8.
Garland DE, Stewart CA, Adkins RH, Hu SS, Rosen C, Liotta FJ, Weinstein DA.
Department of Neurotrauma, Rancho Los Amigos Medical Center, Downey, California 90242.

Dual-photon absorptiometry characterized bone loss in males aged less than 40 years after complete traumatic paraplegic and quadriplegic spinal cord injury. Total bone mass of various regions and bone mineral density (BMD) of the knee were measured in 55 subjects. Three different populations were partitioned into four groups: 10 controls (healthy, age matched); 25 acutely injured (114 days after injury), with 12 reexamined 16 months after injury; and 20 chronic (greater than 5 years after injury). Significant differences (p less than 0.0001) in bone mass mineral between groups at the arms, pelvis, legs, distal femur, and proximal tibia were found, with no differences for the head or trunk. Post hoc analyses indicated no differences between the acutely injured at 16 months and the chronically injured. Paraplegic and quadriplegic subjects were significantly different only at the arms and trunk, but were highly similar at the pelvis and below. In the acutely injured, a slight but statistically insignificant rebound was noted above the pelvis. Regression techniques demonstrated early, rapid, linear (p less than 0.0001) decline of bone below the pelvis. Bone mineral loss occurs throughout the entire skeleton, except the skull. Most bone loss occurs rapidly and below the pelvis. Homeostasis is reached by 16 months at two thirds of original bone mass, near fracture threshold.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 1569500 [PubMed - indexed for MEDLINE]

Changes of tibia bone properties after spinal cord injury: effects of early intervention.

Arch Physical Medicine Rehabilitation. 1999 Feb;80(2):214-20.
de Bruin ED, Frey-Rindova P, Herzog RE, Dietz V, Dambacher MA, Stussi E.
Department of Material Sciences, Laboratory for Biomechanics ETH, Zurich, Switzerland.

OBJECTIVE: To evaluate the effectiveness of an early intervention program for attenuating bone mineral density loss after acute spinal cord injury (SCI) and to estimate the usefulness of a multimodality approach in diagnosing osteoporosis in SCI. DESIGN: A single-case, experimental, multiple-baseline design. SETTING: An SCI center in a university hospital. METHODS: Early loading intervention with weight-bearing by standing and treadmill walking. PATIENTS: Nineteen patients with acute SCI. OUTCOME MEASURES: (1) Bone density by peripheral computed tomography and (2) flexural wave propagation velocity with a biomechanical testing method. RESULTS: Analysis of the bone density data revealed a marked decrease of trabecular bone in the nonintervention subjects, whereas early mobilized subjects showed no or insignificant loss of trabecular bone. A significant change was observed in 3 of 10 subjects for maximal and minimal area moment of inertia. Measurements in 19 subjects 5 weeks postinjury revealed a significant correlation between the calculated bending stiffness of the tibia and the maximal and minimal area moment of inertia, respectively. CONCLUSION: A controlled, single-case, experimental design can contribute to an efficient tracing of the natural history of bone mineral density and can provide relevant information concerning the efficacy of early loading intervention in SCI. The combination of bone density and structural analysis could, in the long term, provide improved fracture risk prediction in patients with SCI and a refined understanding of the bone remodeling processes during initial immobilization after injury.

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PMID: 10025500 [PubMed - indexed for MEDLINE]

Effects of a dynamic versus a static prone stander on bone material density and behavior in four children with severe cerebral palsy

Pediatric Physical Therapy 2002;14:38-46.
Bjorg Gudjonsdottir, MS, PT, Vicki Stemmons Mercer, PhD, PT
Division of Physical Therapy, University of North Carolina at Chapel Hill, Chapel Hill, NC

PURPOSE: in this case series, we examined how two types of prone standers affected bone material density and behavioral variables in four children of preschool age with severe cerebral palsy. METHODS: In phase one, four children of preschool age participated in an eight-week standing program, standing for 30 minutes a day, five days a week. Two children stood in a conventional stander, and two stood in a new type of motorized (dynamic) stander that provides intermittent weight bearing. Measurements of bone material density before and after the program revealed increases in bone material density in both children who used a dynamic stander and one child who used a static stander. In phase two, all four subjects stood in both types of stander during three separate test sessions. RESULT: Measures of behavioral variables, including behavioral state, reactivity, goal directedness, and attention span, indicated little or no effect of type of stander on behavior. CONCLUSIONS: These results suggest there is potential value in additional research concerning the effects of static and dynamic standers on bone material density and behavior in children with cerebral palsy.

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Mobility status and bone density in cerebral palsy.

Wilmshurst S, Ward K, Adams JE, Langton CM, Mughal MZ.
Arch Dis Child. 1996 Aug;75(2):164-5.
Department of Pediatrics, St Mary's Hospital, Manchester.

The spinal bone mineral density (SBMD) and calcaneal broadband ultrasound attenuation (BUA) was measured in 27 children with cerebral palsy. They were categorised into four mobility groups: mobile with an abnormal gait, mobile with assistance, non-mobile but weight bearing, non-mobile or weight bearing. Mean SD scores for BUA and SBMD differed among mobility groups (analysis of variance, p < 0.001 and p = 0.078, respectively).

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PMID: 8869203 [PubMed - indexed for MEDLINE]

Effect of prolonged bed rest on bone mineral.

Metabolism. 1970 Dec; 19(12): 1071-84.
Donaldson CL, Hulley SB, Vogel JM, Hattner RS, Bayers JH, McMillan DE.

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PMID: 4321644 [PubMed - indexed for MEDLINE]

Calcium balance in paraplegic patients: influence of injury duration and ambulation.

Arch Phys Med Rehabil. 1978 Oct;59(10):447-50.
Kaplan PE, Gandhavadi B, Richards L, Goldschmidt J.

Calcium metabolic balance determinations, which have been done in various clinical and experimental conditions, were applied to the study of 8 spinal cord injured patients receiving a diet with 1600 mg calcium and 85 to 120 gm protein daily. All of the patients had hypercalciuria prior to ambulation. Those with spinal cord injuries of less than 3 months duration (early group) had a calcium balance of -27 mg before ambulation and 235 mg after ambulation. Patients with spinal cord injuries of 6 months or more duration (late group) had calcium balances of 55 mg before ambulation and 175 mg after ambulation. Ambulation significantly decreased the hypercalciuria and modified the calcium balance in a positive direction. Smaller changes were noted in the responses of the late group than in those of the early group. Early ambulation will probably prevent bone loss, calcium stones in the genitourinary tract, and other sequellae of negative calcium balance.

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PMID: 718407 [PubMed - indexed for MEDLINE]

The effect of a weight-bearing physical activity program on bone mineral content and estimated volumetric density in children with spastic cerebral palsy.

J Pediatr 1999 Jul;135(1):115-7.
Chad KE, Bailey DA, McKay HA, Zello GA, Snyder RE.
College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.

After an 8-month physical activity intervention in children with cerebral palsy, increases in femoral neck bone mineral content (BMC) (9.6%), volumetric bone mineral density (v BMD) (5.6%), and total proximal femur BMC (11.5%) were observed in the intervention group (n = 9) compared with control subjects (n = 9; femoral neck BMC, -5. 8%; v BMD, -6.3%; total proximal femur BMC, 3.5%).

Publication Types:
• Clinical Trial
• Randomized Controlled Trial
For the complete document, please visit www.pubmed.com or your local medical library.
PMID: 10393617 [PubMed - indexed for MEDLINE]

Bone mineral status in paraplegic patients who do or do not perform standing.
Osteoporos Int. 1994 May;4(3):138-43.
Goemaere S, Van Laere M, De Neve P, Kaufman JM.
Department of Rheumatology, University Hospital of Ghent, Belgium.

Bone mineral density (BMD) was assessed by dual-photon X-ray absorptiometry at the lumbar spine (L3, L4), the proximal femur and the femoral shaft, and by single-photon absorptiometry at the forearm in 53 patients with complete traumatic paraplegia of at least 1 year's duration and in age- and sex-matched healthy controls. The patients did (n = 38) or did not (n = 15) regularly perform passive weightbearing standing with the aid of a standing device. Compared with the controls, the BMD of paraplegic patients was preserved in the lumbar spine and was markedly decreased in the proximal femur (33%) and the femoral shaft (25%). When considering all patients performing standing, they had a better-preserved BMD at the femoral shaft (p = 0.009), but not at the proximal femur, than patients not performing standing. BMD at the lumbar spine (L3, L4) was marginally higher in the standing group (significant only for L3; p = 0.040). A subgroup of patients performing standing with use of long leg braces had a significantly higher BMD at the proximal femur than patients using a standing frame or a standing wheelchair (p = 0.030). The present results suggest that passive mechanical loading can have a beneficial effect on the preservation of bone mass in osteoporosis found in paraplegics.

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PMID: 8069052 [PubMed - indexed for MEDLINE]

Osteoporosis, calcium and physical activity.
CMAJ. 1987 Mar 15;136(6):587-93.
Martin AD, Houston CS.

Sales of calcium supplements have increased dramatically since 1983, as middle-aged women seek to prevent or treat bone loss due to osteoporosis. However, epidemiologic studies have failed to support the hypothesis that larger amounts of calcium are associated with increased bone density or a decreased incidence of fractures. The authors examine the evidence from controlled trials on the effects of calcium supplementation and physical activity on bone loss and find that weight-bearing activity, if undertaken early in life and on a regular basis, can increase the peak bone mass of early adulthood, delay the onset of bone loss and reduce the rate of loss. All of these factors will delay the onset of fractures. Carefully planned and supervised physical activity programs can also provide a safe, effective therapy for people who have osteoporosis.

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PMID: 3545420 [PubMed - indexed for MEDLINE]

Weight-bearing exercise training and lumbar bone mineral content in postmenopausal women.
Ann Intern Med. 1988 Jun;108(6):824-8.
Dalsky GP, Stocke KS, Ehsani AA, Slatopolsky E, Lee WC, Birge SJ.
Washington University School of Medicine, St. Louis, Missouri.

STUDY OBJECTIVE: To assess the effect of weight-bearing exercise training and subsequent detraining on lumbar bone mineral content in postmenopausal women. DESIGN: Non-randomized, controlled, short-term (9 months) trial and long-term (22 months) exercise training and detraining (13 months). SETTING: Section of applied physiology at a university school of medicine. PATIENTS: Thirty-five healthy, sedentary postmenopausal women, 55 to 70 years old. All women completed the study. There was 90% compliance with exercise training. INTERVENTIONS: All women were given calcium, 1500 mg daily. The exercise group did weight-bearing exercise (walking, jogging, stair climbing) at 70% to 90% of maximal oxygen uptake capacity for 50 to 60 min, 3 times weekly. MEASUREMENTS AND MAIN RESULTS: Bone mineral content increased 5.2% (95% confidence interval [CI], 2.0% to 8.4%; P = 0.0037) above baseline after short-term training whereas there was no change (-1.4%) in the control group. After 22 months of exercise, bone mineral content was 6.1% (95% CI, 3.9% to 8.3% above baseline; P = 0.0001) in the long-term training group. After 13 months of decreased activity, bone mass was 1.1% above baseline in the detraining group. CONCLUSIONS: Weight-bearing exercise led to significant increases above baseline in bone mineral content which were maintained with continued training in older, postmenopausal women. With reduced weight-bearing exercise, bone mass reverted to baseline levels. Further studies are needed to determine the threshold exercise prescription that will produce significant increases in bone mass.

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PMID: 3259410 [PubMed - indexed for MEDLINE]

Hypokinesia-induced negative net calcium balance reversed by weight-bearing exercise.
Aviat Space Environ Med. 1987 Apr;58(4):308-14.
Lutz J, Chen F, Kasper CE.

Negative calcium balance and bone loss occurring with immobilization and hypokinesia have been attributed to a lack of weight bearing on bones. The effects of weight-bearing exercise for promotion of calcium balance after hypokinesia were examined. Rats were randomly assigned to either hypokinetic suspension for 28 d or to a control sedentary group, free to move about their cages at will. After 28 d, the rats in each group were randomly subdivided to either post-hypokinetic forced running (HR), post-hypokinetic sedentary (HS), control forced running (CR), or control sedentary (CS) groups. Net calcium balance was then determined for 25 consecutive days. Net calcium balance of HR was negative for the first 5-d period of recovery and then became positive; that of HS was negative for 25 d; that of CR and CS remained essentially positive. Net calcium absorption paralleled net calcium balance. Forced running was effective in reestablishment of positive net calcium balance after 28 d of decreased weight bearing.

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PMID: 3579816 [PubMed - indexed for MEDLINE]

Bone dynamics: stress, strain and fracture.
J Sports Sci. 1987 Summer;5(2):155-63.
Martin AD, McCulloch RG.
Sport and Exercise Sciences Research Institute, University of Manitoba, Winnipeg, Canada.

Bone is a dynamic tissue whose functional mass is controlled by the balance between the endocrine drive towards bone resorption and the mechanically-engendered drive towards bone formation. Strain is the key intermediate variable between loading forces and bone remodelling. Animal studies have shown that static loading of bone has no osteogenic effect; bone loss occurs as if there were no loading at all. However, dynamic loading, that is, cyclic change in internal strain, is strongly osteogenic, with relatively few cycles required for maximum effect. However, if a sufficient number of cycles is applied, repetitive loading can cause stress fractures. This number decreases as internal strains increase. Thus strain redistribution within bone, as caused by muscle fatigue or improper sports equipment, is a significant cause of fracture.

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PMID: 3326949 [PubMed - indexed for MEDLINE]

The influence of activity on calcium metabolism.
J Nutr Sci Vitaminol (Tokyo). 1985 Dec;31 Suppl:S41-4.
Whedon GD.

Many studies and observations have shown the bone-losing effects of physical inactivity of various forms. Contrariwise, less precise studies and observations have supported the reasonable premise that mechanical loading of the skeleton via physical activity shifts the balance of bone remodeling in favor of bone formation, and appears to do so at all ages. Some interesting starts have been made in research to discover the mechanisms of the action on bone of mechanical loading, but many pathways remain to be explored. Besides the mechanical forces, we need to know more about the interrelations of muscle function, probably mediated through muscle-tendon pull on periosteum, and more about other likely influences, notably changes in circulation to bones. The practical significance relative to calcium metabolism and aging of what has been learned thus far on the effects of activity, is that prolonged inactivity, either in a chair or in bed, is to be avoided, because of its deleterious effects, and that reasonably energetic gravitational exercise, such as walking or possibly jogging, promotes maintenance of bone health.

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PMID: 3915756 [PubMed - indexed for MEDLINE]

Low magnitude mechanical loading is osteogenic in children with disabling conditions.
J Bone Miner Res. 2004 Mar;19(3):360-9. Epub 2004 Jan 27. Links
Ward K, Alsop C, Caulton J, Rubin C, Adams J, Mughal Z.
Clinical Radiology, Imaging Science & Biomedical Engineering, University of Manchester, Manchester, United Kingdom.

The osteogenic potential of short durations of low-level mechanical stimuli was examined in children with disabling conditions. The mean change in tibia vTBMD was +6.3% in the intervention group compared with -11.9% in the control group. This pilot randomized controlled trial provides preliminary evidence that low-level mechanical stimuli represent a noninvasive, non-pharmacological treatment of low BMD in children with disabling conditions. INTRODUCTION: Recent animal studies have demonstrated the anabolic potential of low-magnitude, high-frequency mechanical stimuli to the trabecular bone of weight-bearing regions of the skeleton. The main aim of this prospective, double-blind, randomized placebo-controlled pilot trial (RCT) was to examine whether these signals could effectively increase tibial and spinal volumetric trabecular BMD (vTBMD; mg/ml) in children with disabling conditions. MATERIALS AND METHODS: Twenty pre-or postpubertal disabled, ambulant, children (14 males, 6 females; mean age, 9.1 +/- 4.3 years; range, 4-19 years) were randomized to standing on active (n = 10; 0.3g, 90 Hz) or placebo (n = 10) devices for 10 minutes/day, 5 days/week for 6 months. The primary outcomes of the trial were proximal tibial and spinal (L2) vTBMD (mg/ml), measured using 3-D QCT. Posthoc analyses were performed to determine whether the treatment had an effect on diaphyseal cortical bone and muscle parameters. RESULTS AND CONCLUSIONS: Compliance was 44% (4.4 minutes per day), as determined by mean time on treatment (567.9 minutes) compared with expected time on treatment over the 6 months (1300 minutes). After 6 months, the mean change in proximal tibial vTBMD in children who stood on active devices was 6.27 mg/ml (+6.3%); in children who stood on placebo devices, vTBMD decreased by -9.45 mg/ml (-11.9%). Thus, the net benefit of treatment was +15.72 mg/ml (17.7%; p = 0.0033). In the spine, the net benefit of treatment, compared with placebo, was +6.72 mg/ml, (p = 0.14). Diaphyseal bone and muscle parameters did not show a response to treatment. The results of this pilot RCT have shown for the first time that low-magnitude, high-frequency mechanical stimuli are anabolic to trabecular bone in children, possibly by providing a surrogate for suppressed muscular activity in the disabled. Over the course of a longer treatment period, harnessing bone's sensitivity to these stimuli may provide a non-pharmacological treatment for bone fragility in children.

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PMID: 15040823 [PubMed - indexed for MEDLINE]

Pathological fractures in patients with cerebral palsy.
J Pediatr Orthop B. 1996 Fall;5(4):232-8.
Comment in: J Pediatr Orthop B. 1996 Fall;5(4):223-4.
Brunner R, Doderlein L.
Department of Paediatric Orthopaedics, University of Basel, Switzerland.

A retrospective study was made of 37 patients with 54 fractures that occurred without significant trauma. The morbidity and causes of these pathological fractures in patients with cerebral palsy were analyzed. The major causes for the fractures were long and fragile lever arms and stiffness in major joints, particularly the hips and knees. An additional factor was severe osteoporosis following a long period of postoperative immobilization. Seventy-four percent of the fractures occurred in the femoral shaft and supracondylar region. Stress fractures were rare (7%) and involved only the patella. Conservative treatment was sufficient in most cases but surgical fixation provided a good alternative for fractures of the femoral shaft. Intraarticular fractures with joint incongruity resulted in a decreased level of activity of the patient. Since osteoporosis is a major risk factor, patients with cerebral palsy should bear weight to prevent pathological fractures. Any stiffness of major joints and extended periods of immobilization should be avoided.

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PMID: 8897254 [PubMed - indexed for MEDLINE]

Bone density and metabolism in children and adolescents with moderate to severe cerebral palsy.
Pediatrics. 2002 Jul;110(1 Pt 1):e5.
Henderson RC, Lark RK, Gurka MJ, Worley G, Fung EB, Conaway M, Stallings VA, Stevenson RD.
Department of Orthopaedics, University of North Carolina, Chapel Hill, North Carolina 27599, USA. rchh@med.unc.edu

OBJECTIVES: Diminished bone density and a propensity to fracture with minimal trauma are common in children and adolescents with moderate to severe cerebral palsy (CP). The purpose of this study was to provide a detailed evaluation of bone mineral density (BMD) and metabolism in this population and to assess the relationship of these measures to multiple other clinical, growth, and nutrition variables. METHODS: The study group consisted of 117 subjects ages 2 to 19 years (mean: 9.7 years) with moderate to severe CP as defined by the Gross Motor Functional Classification scale. Population-based sampling was used to recruit 62 of the participants, which allows for estimations of prevalence. The remaining 55 subjects were a convenience sampling from both hospital- and school-based sources. The evaluation included measures of BMD, a detailed anthropometric assessment of growth and nutritional status, medical and surgical history, the Child Health Status Questionnaire, and multiple serum analyses. BMD was measured in the distal femur, a site specifically developed for use in this contracted population, and the lumbar spine. BMD measures were converted to age and gender normalized z scores based on our own previously published control series (n > 250). RESULTS: Osteopenia (BMD z score <-2.0) was found in the femur of 77% of the population-based cohort and in 97% of all study participants who were unable to stand and were older than 9 years. BMD was not as low in the lumbar spine (population-based cohort mean +/- standard error z score: -1.8 +/- 0.1) as in the distal femur (mean z score: -3.1 +/- 0.2). Fractures had occurred in 26% of the children who were older than 10 years. Multiple clinical and nutritional variables correlated with BMD z scores, but interpretation of these findings is complicated by covariance among variables. In stepwise regression analyses, it was found that severity of neurologic impairment as graded by Gross Motor Functional Classification level, increasing difficulty feeding the child, use of anticonvulsants, and lower triceps skinfold z scores (in decreasing order of importance) all independently contribute to lower BMD z scores in the femur. CONCLUSIONS: Low BMD is prevalent in children with moderate to severe CP and is associated with significant fracture risk. The underlying pathophysiology is complex, with multiple factors contributing to the problem and significant variation between different regions of the skeleton.

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PMID: 12093986 [PubMed - indexed for MEDLINE]

Skeletal cell stresses and bone adaptation.
Am J Med Sci. 1998 Sep;316(3):176-83.
McLeod KJ, Rubin CT, Otter MW, Qin YX.
Musculoskeletal Research Laboratory, Health Sciences Center, State University of New York, Stony Brook 11794-8181, USA. kmcleod@ccmail.sunysb.edu

There is no tissue in which mechanical stresses have been studied in more detail than the skeletal system, this focus arising primarily because bone plays a clear structural role in the body. However, the hypothesis that the skeleton represents an optimally designed structure has contributed remarkably little to our understanding of the development and adaptive capabilities of bone tissue. Recent investigations on the consequences of mechanical, hydrostatic, and electrical stresses on the cells of bone tissue have served to redirect the discussion of bone modeling and remodeling processes. These studies have refocused attention on the importance of chronic low-level dynamic stresses in mediating the physiologic response of bone tissue. Important recent observations suggest that an approach premised on the self-organizational properties of bone tissue may lead to significant improvements in our understanding and control of bone morphologic development, adaptation, and healing.

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PMID: 9749559 [PubMed - indexed for MEDLINE]

Osteogenesis imperfecta: rehabilitation approach with infants and young children.
Arch Phys Med Rehabilitation. 1984 Sep;65(9):537-41.
Binder H, Hawks L, Graybill G, Gerber NL, Weintrob JC.

A rehabilitation approach, consisting of initial handling and positioning followed by functional and formal strengthening exercises, was developed for the child with severe progressive osteogenesis imperfecta (OI). The program was developed because of the increased life expectancy for infants and children with severe progressive OI, combined with the lack of published reports dealing with their rehabilitation. The program can be followed easily by parents or therapists with regular monitoring by a psychiatrist. The goals are to improve the life span as well as the quality of life of these children by preventing the following: (1) positional contractures and deformities, (2) muscle weakness and osteoporosis, and (3) malalignment of the lower extremity joints prohibiting weight-bearing. Implementation of the program requires full cooperation of the parents. The initial results in four children between the ages of 3 and 11 years are encouraging. The benefits of increased strength and mobility leading to more age-appropriate activities and behaviors outweigh the only observed negative result, that is trauma-related lower extremity fractures in children with milder disease, and therefore greater mobility and higher activity levels.

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PMID: 6477088 [PubMed - indexed for MEDLINE]

Nonoperative treatment of osteogenesis imperfecta: orthotic and mobility management.
Clin Orthop Relat Res. 1981 Sep;(159):111-22.
Bleck EE.

The problem of osteoporosis superimposed on the basic collagen defect of osteogenesis imperfecta has been approached by the use of plastic containment orthoses for the lower limbs, in addition to developmentally staged mobility devices that assist early standing and walking. The purpose of forcing early weight-bearing is to provide stress to the lower limb bones in order to minimize osteoporosis, prevent refracture and deformity, and curb subsequent immobilization osteoporosis, thus breaking a vicious cycle. Management goals are based upon adult needs for independence: efficiency in daily living activities and in mobility. These goals were reached in most of our patients via use of plastic orthoses, early weight-bearing, and electrically powered wheelchairs. Manual osteoclasis of the tibia followed by plastic orthoses utilizing principles of fluid compression to support fractured or structurally weak bones appeared successful at the time of follow-up. Intramedullary rodding of the femur was necessary in most of the 12 children with osteogenesis imperfecta congenita. Supplementary plastic orthoses have reduced the refracture rate in both the tibia and the femur. Social integration of the children was reflected by the fact that among the 12 OI congenita cases, ten were attending regular educational institutions. Twelve OI tarda children fared well, all attaining complete independence in daily living, mobility and ambulation. Seven of this group were treated with intramedullary rodding of the femur or tibia and with plastic orthoses. Five patients required no treatment.

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PMID: 7285447 [PubMed - indexed for MEDLINE]

The Benefits of Standing in General (Overview)

Considerations related to weight-bearing programs in children with developmental disabilities.

Phys Ther. 1992 Jan;72(1):35-40.
Stuberg WA.
Meyer Rehabilitation Institute, University of Nebraska Medical Center, Omaha 68198-5450.

Standing is a common modality used in the management of children with developmental disabilities. The purpose of this article is to examine the scientific basis for standing programs, with specific emphasis on the known effects of weight bearing on bone development. Guidelines for the use of standing programs are presented, and the supporting rationale is discussed.

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PMID: 1728047 [PubMed - indexed for MEDLINE]

Use of prolonged standing for individuals with spinal cord injuries.

Phys Ther. 2001 Aug;81(8):1392-9.
Eng JJ, Levins SM, Townson AF, Mah-Jones D, Bremner J, Huston G.
School of Rehabilitation Sciences, University of British Columbia, T325-2211 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 2B5.janicee@interchange.ubc.ca

BACKGROUND AND PURPOSE: Prolonged standing in people with spinal cord injuries (SCIs) has the potential to affect a number of health-related areas such as reflex activity, joint range of motion, or well-being. The purpose of this study was to document the patterns of use of prolonged standing and their perceived effects in subjects with SCIs. SUBJECTS: The subjects were 152 adults with SCIs (103 male, 49 female; mean age=34 years, SD=8, range=18-55) who returned mailed survey questionnaires. METHODS: A 17-item self-report survey questionnaire was sent to the 463 members of a provincial spinal cord support organization. RESULTS: Survey responses for 26 of the 152 respondents were eliminated from the analysis because they had minimal effects from their injuries and did not need prolonged standing as an extra activity. Of the 126 remaining respondents, 38 respondents (30%) reported that they engaged in prolonged standing for an average of 40 minutes per session, 3 to 4 times a week, as a method to improve or maintain their health. The perceived benefits included improvements in several health-related areas such as well-being, circulation, skin integrity, reflex activity, bowel and bladder function, digestion, sleep, pain, and fatigue. The most common reason that prevented the respondents from standing was the cost of equipment to enable standing. DISCUSSION AND CONCLUSION: Considering the many reported benefits of standing, this activity may be useful for people with SCI. This study identified a number of body systems and functions that may need to be investigated if clinical trials of prolonged standing in people with SCI are undertaken.

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PMID: 11509069 [PubMed - indexed for MEDLINE]

Indications for a home standing program for individuals with spinal cord injury.

J Spinal Cord Med. 1999 Fall;22(3):152-8.
Walter JS, Sola PG, Sacks J, Lucero Y, Langbein E, Weaver F.
Edward Hines Jr. Veterans Affairs Hospital Research Service (151L), Hines, IL 60141, USA.

Additional analyses were conducted on a recently published survey of persons with spinal cord injury (SCI) who used standing mobility devices. Frequency and duration of standing were examined in relation to outcomes using chi square analyses. Respondents (n = 99) who stood 30 minutes or more per day had significantly improved quality of life, fewer bed sores, fewer bladder infections, improved bowel regularity, and improved ability to straighten their legs compared with those who stood less time. Compliance with regular home standing (at least once per week) was high (74%). The data also suggest that individuals with SCI could benefit from standing even if they were to begin several years after injury. The observation of patient benefits and high compliance rates suggest that mobile standing devices should be more strongly considered as a major intervention for relief from secondary medical complications and improvement in overall quality of life of individuals with SCI.

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PMID: 10685379 [PubMed - indexed for MEDLINE]

Follow-up assessment of standing mobility device users.

Assistive Technology. 1998;10(2):84-93.
Dunn RB, Walter JS, Lucero Y, Weaver F, Langbein E, Fehr L, Johnson P, Riedy L.
Rehabilitation Research & Development Center, Edward Hines Jr. Veterans Affairs Hospital, Illinois 60141, USA.

The use of standing devices by spinal cord-injured subjects was investigated through a national survey of a sample of individuals who returned their manufacturer's warranty card to two companies. We obtained a 32% response rate (99/310). The majority of respondents were male (87%) with a median age between 41 and 50 years. Seventy-seven percent were paraplegic and 21% were quadriplegic. Forty percent had between 1 and 5 years experience with their device, and 84% of those responding were currently using their standing device. Forty-one percent used their standing device one to six times a week; two-thirds stood between 30 minutes and 1 hour for each use. Less than 10% of subjects experienced any side effects, such as nausea or headaches, from standing. Twenty-one percent of subjects reported being able to empty their bladder more completely. There was also a favorable response by some individuals on the effects of the standing devices on bowel regularity, reduction of urinary tract infections, leg spasticity, and number of bedsores. Finally, 79% of subjects highly recommended use of standing devices to other people with spinal cord injury. The positive responses of individuals using standing devices is a strong recommendation for the assistive technology community to make these devices more available to individuals with spinal cord injury.

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PMID: 10339284 [PubMed - indexed for MEDLINE]

Standing and its importance in spinal cord injury management.

RESNA 10th Annual Conference San Jose, California 1987
Axelson P, Gurski D, Lasko-Harvill A.
IMEX Inc. San Jose, California
Beneficial Designs, Inc., Santa Cruz, California

A broad spectrum of physiological problems are associated with lack of gravitational stress in the individual with spinal cord injury. Prolonged immobilization results in systemic de-adaptations which include cardiovascular changes, the alteration of calcium homeostasis which leads to bone de-mineralization and risk of urinary calculi.

Weight bearing in the standing posture has been shown to ameliorate many of these problems and offers physiological advantages for the individual with spinal card injury.

There are also significant psychological and social benefits to standing, including improved self-image, and eye-to-eye interpersonal contact. Increased vocational, recreational and daily living independence are additional benefits of standing.

Mobile/Dynamic Standing

The vertical wheeler: a device for ambulation in cerebral palsy.
Arch Phys Med Rehabilitation. 1985 Oct;66(10):717-20.
Manley MT, Gurtowski J.

The vertical wheeler is a new mobility aid that was specifically designed to help improve the quality of life for the handicapped child by providing mobility while standing. Results of a clinical trial in a population of patients with cerebral palsy are presented. Criteria were selected to allow evaluation of the rehabilitative effect of the device on the population. Results showed that the children in this cerebral palsy group all benefited from ambulation with the wheeler. Patients with spastic quadriparesis seemed to gain the most immediate benefit. The device contributed to improved mobility, posture, and self-image. The wheeler was safe and fun for the children. It has the potential for improving the psychologic and medical status of the child with severe locomotion impairment.

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PMID: 4051716 [PubMed - indexed for MEDLINE]

Effects of a dynamic versus a static prone stander on bone material density and behavior in four children with severe cerebral palsy.
Pediatric Physical Therapy 2002;14:38-46.
Bjorg Gudjonsdottir, MS, PT, Vicki Stemmons Mercer, PhD, PT
Division of Physical Therapy, University of North Carolina at Chapel Hill, Chapel Hill, NC

PURPOSE: in this case series, we examined how two types of prone standers affected bone material density and behavioral variables in four children of preschool age with severe cerebral palsy. METHODS: In phase one, four children of preschool age participated in an eight-week standing program, standing for 30 minutes a day, five days a week. Two children stood in a conventional stander, and two stood in a new type of motorized (dynamic) stander that provides intermittent weight bearing. Measurements of bone material density before and after the program revealed increases in bone material density in both children who used a dynamic stander and one child who used a static stander. In phase two, all four subjects stood in both types of stander during three separate test sessions. RESULT: Measures of behavioral variables, including behavioral state, reactivity, goal directedness, and attention span, indicated little or no effect of type of stander on behavior. CONCLUSIONS: These results suggest there is potential value in additional research concerning the effects of static and dynamic standers on bone material density and behavior in children with cerebral palsy.

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Technical note--a patient propelled variable-inclination prone stander.
Prosthet Orthot Int. 1983 Dec;7(3):176-7.
Motloch WM, Brearley MN.

A self-propelled mobile standing device is described with the facility of patient-operated inclination of the support platform, enabling objects on the floor to be reached. The device is provided with a removable tray at the level of the occupant's chest.

For the complete document, please visit www.pubmed.com or your local library. PMID: 6647014 [PubMed - indexed for MEDLINE]

Active (Reciprocal Leg Movement) Standing

Moving the arms to activate the legs.
Exerc Sport Sci Rev. 2006 Jul;34(3):113-20.
Ferris DP, Huang HJ, Kao PC.
Department of Movement Science, University of Michigan, Ann Arbor, MI 48109-2214, USA. ferrisdp@umich.edu

Recent studies on neurologically intact individuals and individuals with spinal cord injury indicate that rhythmic upper limb muscle activation has an excitatory effect on lower limb muscle activation during locomotor-like tasks. This finding suggests that gait rehabilitation therapy after neurological injury should incorporate simultaneous upper limb and lower limb rhythmic exercise to take advantage of neural coupling.

For the complete document, please visit www.pubmed.com or your local medical library.PMID: 16829738 [PubMed - indexed for MEDLINE]

Neural coupling between upper and lower limbs during recumbent stepping.
J Appl Physiol. 2004 Oct;97(4):1299-308. Epub 2004 Jun 4.
Huang HJ, Ferris DP.
Department of Biomedical Engineering, Human Neuromechanics Laboratory, 1206A CCRB, 401 Washtenaw Ave., Univ. of Michigan, Ann Arbor, MI 48109-2214, USA. hjhuang@umich.edu

During gait rehabilitation, therapists or robotic devices often supply physical assistance to a patient's lower limbs to aid stepping. The expensive equipment and intensive manual labor required for these therapies limit their availability to patients. One alternative solution is to design devices where patients could use their upper limbs to provide physical assistance to their lower limbs (i.e., self-assistance). To explore potential neural effects of coupling upper and lower limbs, we investigated neuromuscular recruitment during self-driven and externally driven lower limb motion. Healthy subjects exercised on a recumbent stepper using different combinations of upper and lower limb exertions. The recumbent stepper mechanically coupled the upper and lower limbs, allowing users to drive the stepping motion with upper and/or lower limbs. We instructed subjects to step with 1) active upper and lower limbs at an easy resistance level (active arms and legs); 2) active upper limbs and relaxed lower limbs at easy, medium, and hard resistance levels (self-driven); and 3) relaxed upper and lower limbs while another person drove the stepping motion (externally driven). We recorded surface electromyography (EMG) from six lower limb muscles. Self-driven EMG amplitudes were always higher than externally driven EMG amplitudes (P < 0.05). As resistance and upper limb exertion increased, self-driven EMG amplitudes also increased. EMG bursts during self-driven and active arms and legs stepping occurred at similar times. These results indicate that active upper limb movement increases neuromuscular activation of the lower limbs during cyclic stepping motions. Neurologically impaired humans that actively engage their upper limbs during gait rehabilitation may increase neuromuscular activation and enhance activity-dependent plasticity.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 15180979 [PubMed - indexed for MEDLINE]

Locomotor training after human spinal cord injury: a series of case studies.
Phys Ther. 2000 Jul;80(7):688-700.
Behrman AL, Harkema SJ.

Department of Physical Therapy and University of Florida Brain Institute, University of Florida, Gainesville 32510-0154, USA. abehrman@hp.ufl.edu
Many individuals with spinal cord injury (SCI) do not regain their ability to walk, even though it is a primary goal of rehabilitation. Mammals with thoracic spinal cord transection can relearn to step with their hind limbs on a treadmill when trained with sensory input associated with stepping. If humans have similar neural mechanisms for locomotion, then providing comparable training may promote locomotor recovery after SCI. We used locomotor training designed to provide sensory information associated with locomotion to improve stepping and walking in adults after SCI. Four adults with SCIs, with a mean postinjury time of 6 months, received locomotor training. Based on the American Spinal Injury Association (ASIA) Impairment Scale and neurological classification standards, subject 1 had a T5 injury classified as ASIA A, subject 2 had a T5 injury classified as ASIA C, subject 3 had a C6 injury classified as ASIA D, and subject 4 had a T9 injury classified as ASIA D. All subjects improved their stepping on a treadmill. One subject achieved overground walking, and 2 subjects improved their overground walking. Locomotor training using the response of the human spinal cord to sensory information related to locomotion may improve the potential recovery of walking after SCI.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 10869131 [PubMed - indexed for MEDLINE]

Physical rehabilitation as an agent for recovery after spinal cord injury.
Phys Med Rehabil Clin N Am. 2007 May;18(2):183-202, v.
Behrman AL, Harkema SJ.
Department of Physical Therapy, College of Public Health and Health Professions, P.O. Box 100154, University of Florida, Gainesville, FL 32610-0154, USA. abehrman@phhp.ufl.edu

The initial level of injury and severity of volitional motor and clinically detectable sensory impairment has been considered the most reliable for predicting neurologic recovery of function after spinal cord injury (SCI). This consensus implies a limited expectation for physical rehabilitation interventions as important in the facilitation of recovery of function. The development of pharmacologic and surgical interventions has always been pursued with the intent of altering the expected trajectory of recovery after SCI, but only recently physical rehabilitation strategies have been considered to improve recovery beyond the initial prognosis. This article reviews the recent literature reporting emerging activity-based therapies that target recovery of standing and walking based on activity-dependent neuroplasticity. A classification scheme for physical rehabilitation interventions is also discussed to aid clinical decision making.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 17543768 [PubMed - indexed for MEDLINE]

Physiologic responses to electrically assisted and frame-supported standing in persons with paraplegia.
J Spinal Cord Med. 2003 Winter;26(4):384-9.
Jacobs PL, Johnson B, Mahoney ET.
Department of Neurologic Surgery, University of Miami School of Medicine, Miami, Florida 33136, USA. pjacobs@miamiproject.med.miami.edu

BACKGROUND: Systems of functional electrical stimulation (FES) have been demonstrated to enable some persons with paraplegia to stand and ambulate limited distances. However, the energy costs and acute physiologic responses associated with FES standing activities have not been well investigated. OBJECTIVE: To compare the physiologic responses of persons with paraplegia to active FES-assisted standing (AS) and frame-supported passive standing (PS). METHODS: Fifteen persons with paraplegia (T6-T11) previously habituated to FES ambulation, completed physiologic testing of PS and AS. The AS assessments were performed using a commercial FES system (Parastep-1; Altimed, Fresno, Calif); the PS tests used a commercial standing frame (Easy Stand 5000; Altimed, Fresno, Calif). Participants also performed a peak arm-cranking exercise (ACE) test using a progressive graded protocol in 3-minute stages and 10-watt power output increments to exhaustion. During all assessments, metabolic activity and heart rate (HR) were measured via open-circuit spirometry and 12-lead electrocardiography, respectively. Absolute physiologic responses to PS and AS were averaged over 1-minute periods at 5-minute intervals (5, 10, 15, 20, 25, and 30 minutes) and adjusted relative to peak values displayed during ACE to determine percentage of peak (%pk) values. Absolute and relative responses were compared between test conditions (AS and PS) and across time using two-way analysis of variance. RESULTS: The AS produced significantly greater values of VO2 (43%pk) than did PS (20%pk). The mean HR responses to PS (100-102 beats per minute [bpm] throughout) were significantly lower than during AS, which ranged from 108 bpm at 5 minutes to 132 bpm at test termination. CONCLUSION: Standing with FES requires significantly more energy than does AS and may provide a cardiorespiratory stress sufficient to meet minimal requirements for exercise conditioning.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 14992341 [PubMed - indexed for MEDLINE]

Shaping appropriate locomotive motor output through interlimb neural pathway within spinal cord in humans.
J Neurophysiol. 2008 Jun;99(6):2946-55. Epub 2008 Apr 30.
Kawashima N, Nozaki D, Abe MO, Nakazawa K.
Department of Rehabilitation for the Movement Functions, Research Institute of the National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, Saitama 359-8555, Japan. nori.kawashima@utoronto.ca.

Direct evidence supporting the contribution of upper limb motion on the generation of locomotive motor output in humans is still limited. Here, we aimed to examine the effect of upper limb motion on locomotor-like muscle activities in the lower limb in persons with spinal cord injury (SCI). By imposing passive locomotion-like leg movements, all cervical incomplete (n = 7) and thoracic complete SCI subjects (n = 5) exhibited locomotor-like muscle activity in their paralyzed soleus muscles. Upper limb movements in thoracic complete SCI subjects did not affect the electromyographic (EMG) pattern of the muscle activities. This is quite natural since neural connections in the spinal cord between regions controlling upper and lower limbs were completely lost in these subjects. On the other hand, in cervical incomplete SCI subjects, in whom such neural connections were at least partially preserved, the locomotor-like muscle activity was significantly affected by passively imposed upper limb movements. Specifically, the upper limb movements generally increased the soleus EMG activity during the backward swing phase, which corresponds to the stance phase in normal gait. Although some subjects showed a reduction of the EMG magnitude when arm motion was imposed, this was still consistent with locomotor-like motor output because the reduction of the EMG occurred during the forward swing phase corresponding to the swing phase. The present results indicate that the neural signal induced by the upper limb movements contributes not merely to enhance but also to shape the lower limb locomotive motor output, possibly through interlimb neural pathways. Such neural interaction between upper and lower limb motions could be an underlying neural mechanism of human bipedal locomotion.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 18450579 [PubMed - in process]

Alternate leg movement amplifies locomotor-like muscle activity in spinal cord injured persons.
J Neurophysiol. 2005 Feb;93(2):777-85. Epub 2004 Sep 22.
Kawashima N, Nozaki D, Abe MO, Akai M, Nakazawa K.
Department of Rehabilitation for Movement Functions, Research Institute of National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, Saitama 359-8555, Japan. nori@rehab.go.jp

It is now well recognized that muscle activity can be induced even in the paralyzed lower limb muscles of persons with spinal cord injury (SCI) by imposing locomotion-like movements on both of their legs. Although the significant role of the afferent input related to hip joint movement and body load has been emphasized considerably in previous studies, the contribution of the "alternate" leg movement pattern has not been fully investigated. This study was designed to investigate to what extent the alternate leg movement influenced this "locomotor-like" muscle activity. The knee-locked leg swing movement was imposed on 10 complete SCI subjects using a gait training apparatus. The following three different experimental conditions were adopted: 1) bilateral alternate leg movement, 2) unilateral leg movement, and 3) bilateral synchronous (in-phase) leg movement. In all experimental conditions, the passive leg movement induced EMG activity in the soleus and medial head of the gastrocnemius muscles in all SCI subjects and in the biceps femoris muscle in 8 of 10 SCI subjects. On the other hand, the EMG activity was not observed in the tibialis anterior and rectus femoris muscles. The EMG level of these activated muscles, as quantified by integrating the rectified EMG activity recorded from the right leg, was significantly larger for bilateral alternate leg movement than for unilateral and bilateral synchronous movements, although the right hip and ankle joint movements were identical in all experimental conditions. In addition, the difference in the pattern of the load applied to the leg among conditions was unable to explain the enhancement of EMG activity in the bilateral alternate leg movement condition. These results suggest that the sensory information generated by alternate leg movements plays a substantial role in amplifying the induced locomotor-like muscle activity in the lower limbs.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 15385590 [PubMed - indexed for MEDLINE]

Femoral loads during passive, active, and active-resistive stance after spinal cord injury: a mathematical model.
Frey Law LA, Shields RK.
Clin Biomech (Bristol, Avon). 2004 Mar;19(3):313-21.
Graduate Program in Physical Therapy and Rehabilitation Science, The University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242, USA.

OBJECTIVE: The purpose of this study was to estimate the loading environment for the distal femur during a novel standing exercise paradigm for people with spinal cord injury. DESIGN: A mathematical model based on experimentally derived parameters. BACKGROUND: Musculoskeletal deterioration is common after spinal cord injury, often resulting in osteoporotic bone and increased risk of lower extremity fracture. Potential mechanical treatments have yet to be shown to be efficacious; however, no previous attempts have been made to quantify the lower extremity loading during passive, active, and active-resistive stance. METHODS: A static, 2-D model was developed to estimate the external forces; the activated quadriceps forces; and the overall bone compression and shear forces in the distal femur during passive (total support of frame), active (quadriceps activated minimally), and active-resistive (quadriceps activated against a resistance) stance. RESULTS: Passive, active, and active-resistive stance resulted in maximal distal femur compression estimates of approximately 45%, approximately 75%, and approximately 240% of body weight, respectively. Quadriceps force estimates peaked at 190% of body weight with active-resistive stance. The distal femur shear force estimates never exceeded 24% of body weight with any form of stance. CONCLUSIONS: These results support our hypothesis that active-resistive stance induces the highest lower extremity loads of the three stance paradigms, while keeping shear to a minimum. RELEVANCE: This model allows clinicians to better understand the lower extremity forces resulting from passive, active, and active-resistive stance in individuals with spinal cord injury.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 15003348 [PubMed - indexed for MEDLINE]

Bone loss and muscle atrophy in spinal cord injury: epidemiology, fracture prediction, and rehabilitation strategies.
J Spinal Cord Med. 2006;29(5):489-500.
Giangregorio L, McCartney N.
Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada. lmgiangr@uwaterloo.ca

Individuals with spinal cord injury (SCI) often experience bone loss and muscle atrophy. Muscle atrophy can result in reduced metabolic rate and increase the risk of metabolic disorders. Sublesional osteoporosis predisposes individuals with SCI to an increased risk of low-trauma fracture. Fractures in people with SCI have been reported during transfers from bed to chair, and while being turned in bed. The bone loss and muscle atrophy that occur after SCI are substantial and may be influenced by factors such as completeness of injury or time post injury. A number of interventions, including standing, electrically stimulated cycling or resistance training, and walking exercises have been explored with the aim of reducing bone loss and/or increasing bone mass and muscle mass in individuals with SCI. Exercise with electrical stimulation appears to increase muscle mass and/or prevent atrophy, but studies investigating its effect on bone are conflicting. Several methodological limitations in exercise studies with individuals with SCI to date limit our ability to confirm the utility of exercise for improving skeletal status. The impact of standing or walking exercises on muscle and bone has not been well established. Future research should carefully consider the study design, skeletal measurement sites, and the measurement techniques used in order to facilitate sound conclusions.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 17274487 [PubMed - indexed for MEDLINE]: PMC1949032

Skeletal adaptations to alterations in weight-bearing activity: a comparison of models of disuse osteoporosis.
Sports Med. 2002;32(7):459-76.
Giangregorio L, Blimkie CJ.
Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada.

The removal of regular weight-bearing activity generates a skeletal adaptive response in both humans and animals, resulting in a loss of bone mineral. Human models of disuse osteoporosis, namely bed rest, spinal cord injury and exposure to micro-gravity demonstrate the negative calcium balance, alterations in biochemical markers of bone turnover and resultant loss of bone mineral in the lower limbs that occurs with reduced weight-bearing loading. The site-specific nature of the bone response is consistent in all models of disuse; however, the magnitude of the skeletal adaptive response may differ across models. It is important to understand the various manifestations of disuse osteoporosis, particularly when extrapolating knowledge gained from research using one model and applying it to another. In rats, hindlimb unloading and exposure to micro-gravity also result in a significant bone response. Bone mineral is lost, and changes in calcium metabolism and biochemical markers of bone turnover similar to humans are noted. Restoration of bone mineral that has been lost because of a period of reduced weight bearing may be restored upon return to normal activity; however, the recovery may not be complete and/or may take longer than the time course of the original bone loss. Fluid shear stress and altered cytokine activity may be mechanistic features of disuse osteoporosis. Current literature for the most common human and animal models of disuse osteoporosis has been reviewed, and the bone responses across models compared.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 12015807 [PubMed - indexed for MEDLINE]

A motorized dynamic stander.
Pediatr Phys Ther. 2002 Spring;14(1):49-51.
Gudjonsdottir B, Mercer VS.
Division of Physical Therapy, University of North Carolina at Chapel Hill, Chapel Hill, NC.

PURPOSE: The purpose of this clinical suggestion is to describe a new type of a stander, a dynamic stander. KEY POINTS: The dynamic stander may give children with severe cerebral palsy an opportunity for movement in lower extremities and trunk while they are standing. It may increase their tolerance for standing in a stander for a considerable period of time. In addition, the potential for increased bone mineral density might be greater with a dynamic stander than a conventional stander. The design, development, and initial clinical use of the new type of stander is described. SUMMARY: Some minor problems related to the design of the dynamic stander were noted. Design changes to correct these problems could be easily implemented before the introduction of the stander for more widespread clinical use.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 17053681 [PubMed - in process]

Bone-loading response varies with strain magnitude and cycle number.
J Appl Physiol. 2001 Nov;91(5):1971-6.
Cullen DM, Smith RT, Akhter MP.
Osteoporosis Research Center, Creighton University, Omaha, Nebraska 68131, USA. dcullen@creighton.edu

Mechanical loading stimulates bone formation and regulates bone size, shape, and strength. It is recognized that strain magnitude, strain rate, and frequency are variables that explain bone stimulation. Early loading studies have shown that a low number (36) of cycles/day (cyc) induced maximal bone formation when strains were high (2,000 microepsilon) (Rubin CT and Lanyon LE. J Bone Joint Surg Am 66: 397-402, 1984). This study examines whether cycle number directly affects the bone response to loading and whether cycle number for activation of formation varies with load magnitude at low frequency. The adult rat tibiae were loaded in four-point bending at 25 (-800 microepsilon) or 30 N (-1,000 microepsilon) for 0, 40, 120, or 400 cyc at 2 Hz for 3 wk. Differences in periosteal and endocortical formation were examined by histomorphometry. Loading did not stimulate bone formation at 40 cyc. Compared with control tibiae, tibiae loaded at -800 microepsilon showed 2.8-fold greater periosteal bone formation rate at 400 cyc but no differences in endocortical formation. Tibiae loaded at -1,000 microepsilon and 120 or 400 cyc had 8- to 10-fold greater periosteal formation rate, 2- to 3-fold greater formation surface, and 1-fold greater endocortical formation surface than control. As applied load or strain magnitude decreased, the number of cyc required for activation of formation increased. We conclude that, at constant frequency, the number of cyc required to activate formation is dependent on strain and that, as number of cyc increases, the bone response increases.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 11641332 [PubMed - indexed for MEDLINE]

Modulation of bone loss during calcium insufficiency by controlled dynamic loading.
Calcif Tissue Int. 1986 Apr;38(4):209-16.
Lanyon LE, Rubin CT, Baust G.

Changes in the midshaft cross-sectional area of the ulna were measured in egg-laying turkeys on a diet insufficient in calcium. Left:right comparisons were used to assess the bone loss over a six-week period due to 1) calcium insufficiency, 2) calcium insufficiency plus disuse, and 3) calcium insufficiency and disuse interrupted by a short daily period of intermittent loading applied from an external device. Calcium insufficiency alone in the intact ulna resulted in a 15% reduction in cross-sectional area. In the functionally deprived bones this loss was increased to 32%. In bones where the disuse was interrupted by a single short daily period of loading, the degree of bone loss was significantly modified (P less than 0.006) to 25%. No significant difference in the modulating effect of loading was achieved by varying the peak strain from 0.0015 to 0.003, the strain rate from 0.01 to 0.05, or the duration of the single loading period from 100 sec per day to 25 minutes. All the loading regimes employed had been demonstrated to be osteogenic in mature male birds on a diet sufficient in calcium.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 3085898 [PubMed - indexed for MEDLINE]

Regulation of bone mass by mechanical strain magnitude.
Calcif Tissue Int. 1985 Jul;37(4):411-7.
Rubin CT, Lanyon LE.

The in vivo remodeling behavior within a bone protected from natural loading was modified over an 8-week period by daily application of 100 consecutive 1 Hz load cycles engendering strains within the bone tissue of physiological rate and magnitude. This load regime resulted in a graded dose:response relationship between the peak strain magnitude and change in the mass of bone tissue present. Peak longitudinal strains below 0.001 were associated with bone loss which was achieved by increased remodeling activity, endosteal resorption, and increased intra-cortical porosis. Peak strains above 0.001 were associated with little change in intra-cortical remodeling activity but substantial periosteal and endosteal new bone formation.

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 3930039 [PubMed - indexed for MEDLINE]

Static vs dynamic loads as an influence on bone remodelling.
J Biomech. 1984;17(12):897-905.
Lanyon LE, Rubin CT.

Remodelling activity in the avian ulna was assessed under conditions of disuse alone, disuse with a superimposed continuous compressive load, and disuse interrupted by a short daily period of intermittent loading. The ulnar preparation consisted of the 110mm section of the bone shaft between two submetaphyseal osteotomies. Each end of the preparation was transfixed by a stainless steel pin and the shaft either protected from normal functional loading with the pins joined by external fixators, loaded continuously in compression by joining the pins with springs, or loaded intermittently in compression for a single 100s period per day by engaging the pins in an Instron machine. Similar loads (525 N) were used in both static and dynamic cases. The strains engendered were determined by strain gauges, and at their maximum around the bone's midshaft were -0.002. The intermittent load was applied at a frequency of 1 Hz as a ramped square wave, with a rate of change of strain during the ramp of 0.01 s-1. Peak strain at the midshaft of the ulna during wing flapping in the intact bone was recorded from bone bonded strain gauges in vivo as -0.0033 with a maximum rate of change of strain of 0.056 s-1. Examination of bone sections from the midpoint of the preparation after an 8 week period indicated that in both non-loaded and statically loaded bones there was an increase in both endosteal diameter and intra cortical porosity. These changes produced a decrease in cross sectional area which was similar in the two groups (-13%).(ABSTRACT TRUNCATED AT 250 WORDS)

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 6520138 [PubMed - indexed for MEDLINE].

Vibration while Standing

Circulatory hypokinesis and functional electric stimulation during standing in persons with spinal cord injury.
Arch Phys Med Rehabil. 2001 Nov;82(11):1587-95.
Faghri PD, Yount JP, Pesce WJ, Seetharama S, Votto JJ.
School of Allied Health, University of Connecticut, Storrs, CT 06269-2101, USA. Pouran.Faghri@uconn.edu

OBJECTIVE: To evaluate the effects of functional electric stimulation (FES) of lower limb muscles during 30 minutes of upright standing on the central and peripheral hemodynamic response in persons with spinal cord injury (SCI). DESIGN: A repeated-measure design. Subjects were used as their own control and underwent 2 testing protocols of FES-augmented standing (active standing) and non-FES standing (passive standing). SETTING: Rehabilitation hospital. PARTICIPANTS: Fourteen individuals with SCI (7 with tetraplegia, 7 with paraplegia). INTERVENTIONS: During active standing, FES was administered to 4 muscle groups of each leg in an overlapping fashion to produce a pumping mechanism during standing. During passive standing, subjects stood for 30 minutes using a standing frame with no FES intervention. MAIN OUTCOME MEASURES: Central hemodynamic responses of stroke volume, cardiac output, heart rate, arterial blood pressure, total peripheral resistance (TPR), and rate pressure product (RPP) were evaluated by impedance cardiography. All measurements were performed during supine and sitting positions before and after standing, and during 30 minutes of upright standing. RESULTS: Comparisons between the groups with paraplegia and tetraplegia showed a significant increase in heart rate in the paraplegics after 30 minutes of active standing. During active standing, paraplegics' heart rate increased by 18.2% (p = .015); during passive standing, it increased by 6% (p = .041). TPR in the tetraplegics significantly (p = .003) increased by 54% when compared with the paraplegics during passive standing. Overall, the tetraplegic group had a significantly lower systolic blood pressure (p = .013) and mean arterial pressure (p = .048) than the paraplegics during passive standing. These differences were not detected during active standing. When data were pooled from both groups and the overall groups response to active and passive standing were compared, the results showed that cardiac output, stroke volume, and blood pressure significantly decreased (p < .05) during 30 minutes of passive standing, whereas TPR significantly increased (p < .05). All of the hemodynamic variables were maintained during 30 minutes of active standing, and there were increases in RPP and heart rate after 30 minutes of active standing. CONCLUSION: FES of the lower extremity could be used by persons with SCI as an adjunct during standing to prevent orthostatic hypotension and circulatory hypokinesis. This effect may be more beneficial to those with tetraplegia who have a compromised autonomic nervous system and may not be able to adjust their hemodynamics to the change in position. Copyright 2001 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

For the complete document, please visit www.pubmed.com or your local medical library. PMID: 11689980 [PubMed - indexed for MEDLINE]

Bone-loading response varies with strain magnitude and cycle number.
J Appl Physiol. 2001 Nov;91(5):1971-6.
Cullen DM, Smith RT, Akhter MP.
Osteoporosis Research Center, Creighton University, Omaha, Nebraska 68131, USA. dcullen@creighton.edu

Mechanical loading stimulates bone formation and regulates bone size, shape, and strength. It is recognized that strain magnitude, strain rate, and frequency are variables that explain bone stimulation. Early loading studies have shown that a low number (36) of cycles/day (cyc) induced maximal bone formation when strains were high (2,000 microepsilon) (Rubin CT and Lanyon LE. J Bone Joint Surg Am 66: 397-402, 1984). This study examines whether cycle number directly affects the bone response to loading and whether cycle number for activation of formation varies with load magnitude at low frequency. The adult rat tibiae were loaded in four-point bending at 25 (-800 microepsilon) or 30 N (-1,000 microepsilon) for 0, 40, 120, or 400 cyc at 2 Hz for 3 wk. Differences in periosteal and endocortical formation were examined by histomorphometry. Loading did not stimulate bone formation at 40 cyc. Compared with control tibiae, tibiae loade