Internal fixation of oblique metacarpal fractures. A biomechanical evaluation by impact loading.

Internal fixation of oblique metacarpal fractures was studied in a cadaver model by impact loading. One hundred twenty fresh-frozen human metacarpals underwent compressive and bending impacts after oblique osteotomy and internal fixation. Dorsal plating with lag screws, 2 dorsal lag screws (2-screws), crossed Kirschner wire tension band (crossed K-wire), 5 stacked intramedullary Kirschner wire (5-rod), and paired intramedullary Kirschner wire (2-rod) were used. The failure occurred within 6 msec in the compressive impact and was almost immediate in the bending impact. The dorsal plate and the intramedullary rod fixations were the strongest and were not significantly different from the intact specimens in compressive impact; they were, however, 19% weaker in bending impact. The 2-screws was the weakest fixation in this group. This fixation was 59% weaker in compressive impact and 47% weaker in bending impact compared with the dorsal plating.