Distal radius fractures are commonly treated with cast immobilization. Variations exist in activity restrictions placed on immobilized patients. No prior studies have assessed fracture displacement in simulated falls while casted/splinted. Simulated fractures of the distal radius and ulna were created in cadaveric forearms. A fall onto outstretched hands was simulated by applying a force through the long axis of the forearm. Each sample went through force testing in a short-arm well-molded fiberglass cast and a commercial fracture splint. Initial and final position lateral radiographs at 0N and 400N of force and dynamic fluoroscopy were taken for calculation of volar tilt at different forces (N). Mean change in volar tilt, radial height, and radial inclination were calculated and compared between groups using paired t-tests. Ten adult cadaveric forearms (6 female specimens, mean age 58.5±17.4 years, BMI 25.7±5.9) were included. Volar tilt, radial height, and radial inclination were similar when specimens were casted or splinted across all forces, with fracture displacement >10° of dorsal tilt (clinically unacceptable) in both groups at 29.2% of idealized adult (70kg) and 40.8% of idealized adolescent (50kg) body weights. Changes in dorsal angulation of fractures when casted and splinted were comparable at 400N of force (13.3±9.2° vs 13.2±8.7°, p=0.945). Fracture displacement was similar between fractures immobilized with well-molded short-arm casts and commercial wrist splints. Simulated fractures displaced when simulated-fall compressive forces were applied. Unacceptable levels of displacement occurred when casted or splinted. This study demonstrates objectively what one might have already suspected: cast/ splint-immobilized fractures can displace when fall-simulation forces are applied to the casted limb. Further work may include additional force patterns and clinical outcome studies assessing activity in cast/splint immobilized healing fractures and maintenance of reduction. Clinical practice guidelines should be developed to guide sports/activity restrictions for patients with cast/splint-immobilized healing fractures.
Dodwell et al. (Wed,) studied this question.