Research Studies

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.

For the complete document, please visit www.pubmed.com or your local medical library.
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
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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]

Calcium balance in paraplegic patients: influence of injury duration and ambulation.
Arch Phys Med Rehabilitation. 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.

For the complete document, please visit www.pubmed.com or your local medical library.
PMID: 718407 [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]