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

Objective: To evaluate the effectiveness of an early intervention program f or attenuating bone mineral density loss after acute spinal cord injury (SC I) 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 tre admill 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 tr abecular bone in the nonintervention subjects, whereas early mobilized subj ects showed no or insignificant loss of trabecular bone. A significant chan ge was observed in 3 of 10 subjects for maximal and minimal area moment of inertia. Measurements in 19 subjects 5 weeks postinjury revealed a signific ant correlation between the calculated bending stiffness of the tibia and t he maximal and minimal area moment of inertia, respectively. Conclusion: A controlled, single-case, experimental design can contribute t o an efficient tracing of the natural history of bone mineral density and c an provide relevant information concerning the efficacy of early loading in tervention in SCI. The combination of bone density and structural analysis could, in the long term, provide improved fracture risk prediction in patie nts with SCI and a refined understanding of the bone remodeling processes d uring initial immobilization after injury. (C) 1999 by the American Congres s of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.