Category: Effects of Immobilization

date: 08/01/1990
author: Lee JJ, Lyne ED.
publication: J Pediatr Orthop. 1990 Jul-Aug;10(4):497-500.
pubmed_ID: 2358490

The incidence (42%) of vitamin D abnormalities is high in severely handicapped children and young adults who sustain fractures, especially those who sustain multiple fractures. Fractures occur primarily in the lower extremity and heal with simple immobilization. In patients with normal vitamin D levels, a history of a significant traumatic event should be identified and child abuse ruled out. Vitamin D-deficient patients respond to nutritional and vitamin D supplementation, with decreased fracture incidence.

date: 10/01/1976
author: Miller PR, Glazer DA.
publication: Clin Orthop Relat Res. 1976 Oct;(120):134-7.
pubmed_ID: 975648
Outside_URL:
This report deals with the treatment of 31 spontaneous fractures which occurred in 50 institutionalized patients who were bedridden primarily because of severe cerebral palsy associated with brain injury. More than one-half of the group sustained a spontaneous fracture. Satisfactory healing of all fractures with a minimum of complications occurred without any immobilization or realignment. In 4 patients with delayed compound wounds, the treatment consisted of resection of the protruding portion of the bone after allowing the bony protrusion to wall itself off.

date: 12/01/1985
author: Whedon GD.
publication: J Nutr Sci Vitaminol (Tokyo). 1985 Dec;31 Suppl:S41-4.
pubmed_ID: 3915756
Outside_URL: http://www.ncbi.nlm.nih.gov/pubmed/3915756
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.

date: 02/01/1999
author: De Bruin ED, Frey-Rindova P, Herzog RE, Dietz V, Dambacher MA, Stussi E.
publication: Arch Physical Medicine Rehabilitation. 1999 Feb;80(2):214-20.
pubmed_ID: 10025500

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.

date: 12/19/1970
author: Donaldson CL, Hulley SB, Vogel JM, Hattner RS, Bayers JH, McMillan DE.
publication: Metabolism. 1970 Dec; 19(12): 1071-84
pubmed_ID: 4321644
Outside_URL: http://www.ncbi.nlm.nih.gov/pubmed/4321644
Bone mineral is lost during immobilization. This disuse osteopenia occurs locally in patients with fracture or hemiplegia and is generalized in quadriplegia.

date: 01/01/2001
author: Giangregorio L, Blimkie CJ.
publication: Sports Med. 2002;32(7):459-76.
pubmed_ID: 12015807

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.