Category: Research and Articles

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Bone loss and muscle atrophy in spinal cord injury: epidemiology, fracture prediction, and rehabilitation strategies.

date: 01/01/2006
author: Giangregorio L, McCartney N.
publication: J Spinal Cord Med. 2006;29(5):489-500.
pubmed_ID: 17274487

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.

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

date: 01/01/1981
author: Odeen I, Knutsson E.
publication: Scand J Rehabilitation Medicine. 1981;13(4):117-21.
pubmed_ID: 7347432
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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Bone-loading response varies with strain magnitude and cycle number.

date: 11/01/2001
author: Cullen DM, Smith RT, Akhter MP.
publication: J Appl Physiol. 2001 Nov;91(5):1971-6.
pubmed_ID: 11641332

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.

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Extent and direction of joint motion limitation after prolonged immobility: an experimental study in the rat.

date: 12/01/1999
author: Trudel G, Uhthoff HK, Brown M.
publication: Arch Phys Med Rehabilitation. 1999 Dec;80(12):1542-7.
pubmed_ID: 10597804

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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Nonoperative treatment of osteogenesis imperfecta: orthotic and mobility management.

date: 09/01/1981
author: Bleck EE.
publication: Clin Orthop Relat Res. 1981 Sep;(159):111-22.
pubmed_ID: 7285447

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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Case study to evaluate a standing table for managing constipation.

date: 06/01/2001
author: Hoenig H, Murphy T, Galbraith J, Zolkewitz M.
publication: SCI Nurse 2001 Summer;18(2):74-7.
pubmed_ID: 12035465

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

date: 01/01/1992
author: Stuberg WA.
publication: Phys Ther. 1992 Jan;72(1):35-40.
pubmed_ID: 1728047

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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Reduction of muscular hypertonus by long-term muscle stretch.

date: 01/01/1981
author: Odeen I.
publication: Scand J Rehabilitation Medicine. 1981;13(2-3):93-9.
pubmed_ID: 7345572

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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Reliability and comparison of weight-bearing ability during standing tasks for individuals with chronic stroke.

date: 08/01/2002
author: Eng JJ, Chu KS.
publication: Arch Phys Med Rehabilitation. 2002 Aug;83(8):1138-44.
pubmed_ID: 12161837

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

date: 01/01/1990
author: Tremblay F, Malouin F, Richards CL, Dumas F.
publication: Scand J Rehabilitation Medicine. 1990;22(4):171-80.
pubmed_ID: 2263918

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.