RESUMEN
PURPOSE: To determine the 6 degrees of freedom forces and moments in the distal radius that occur during a pushup or other active wrist motions. METHODS: Eight fresh-frozen cadaveric wrists were moved through 6 physiological motions and held at 1 static pushup position while the force through the distal radius was measured with a 6 degrees of freedom load cell. Three levels of compressive force were applied at the pushup position. RESULTS: Active wrist motions caused axial forces up to 283 N and moments up to 0.7 N-m. Those motions with a smaller range had significantly smaller axial forces than the larger flexion-extension or dart-thrower's motions. With an 89-N pushup force applied, the average maximum axial force was 69 N, the radially directed force was 12 N, and the moment about the radioulnar axis was 2.3 N-m. Linear extrapolation of the forces to 100% body weight indicate that the axial force going through the distal radius would be 663 N, the radial force would be 147 N, and the moment about the radioulnar axis would be 18.6 N-m. CONCLUSIONS: Large distal radius forces and moments can occur during pushup and active wrist motions. There are not only large axial compressive forces but also nontrivial radially directed forces. CLINICAL RELEVANCE: This study may help surgeons and therapists better treat complicated distal radius fractures as well as provide for better comparisons of existing or new distal radius plates and constructs that are designed to treat these complicated loading patterns.
Asunto(s)
Ejercicio Físico/fisiología , Movimiento/fisiología , Radio (Anatomía)/fisiología , Articulación de la Muñeca/fisiología , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos/fisiología , Cadáver , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
PURPOSE: To investigate the effect of a closing wedge osteotomy at the distal ulnar metaphysis on unloading the ulnar side of the wrist. METHODS: Seven fresh frozen cadaver arms mounted in a wrist simulator were used for the analysis. A 6-degrees-of-freedom load cell was mounted on the distal radius and another on the distal ulna. Radioulnar carpal joint forces and transverse distal radioulnar joint (DRUJ) load were measured at static wrist positions and during dynamic wrist motions before and after the distal metaphyseal ulnar shortening osteotomy (DMUSO) was performed. RESULTS: At each static position, significant decreases in ulnar load were noted after DMUSO. In addition, mean and maximum loads decreased for each dynamic wrist motion. There were no statistically significant differences in transverse forces across the DRUJ after DMUSO. CONCLUSION: This study showed that DMUSO is an effective way to decrease the load across the ulnocarpal joint. The geometry of the osteotomy and resultant change in the position of the ulnar head did not increase transverse joint reaction forces. CLINICAL RELEVANCE: This technique is an alternative to open diaphyseal techniques or methods that damage the articular surface of the distal ulna. Clinical studies will be necessary to associate the biomechanical correction noted in this study with clinical symptom improvement.