INTERNAL-FIXATION OF OBLIQUE METACARPAL FRACTURES - A BIOMECHANICAL EVALUATION BY IMPACT LOADING

Internal fixation of oblique metacarpal fractures was studied in a cad aver model by impact loading, One hundred twenty fresh-frozen human me tacarpals underwent compressive and bending impacts after oblique oste otomy 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 int ramedullary Kirschner wire (2-rod) were used, The failure occurred wit hin 6 msec in the compressive impact and was almost immediate in the b ending impact, The dorsal plate and the intramedullary rod fixations w ere the strongest and were not significantly different from the intact specimens in compressive impact; they were, however, 19% weaker in be nding impact, The 2-screws was the weakest fixation in this group, Thi s fixation was 59% weaker in compressive impact and 47% weaker in bend ing impact compared with the dorsal plating.