OBJECTIVETo study the quantitative measurement of the extent of malrotation after interlocking intramedullary nailing of femoral shaft fracture.

METHODCT scan ("routine method") applied in 36 femoral shaft fractures that had been treated with close reduction and interlocking intramedullary nailing. For the judgement of the extent of malrotation, the anteversion of both fracture side and contralateral side were measured and the difference between the 2 sides was evaluated. The increase of anteversion represented internal rotation of the distal fragment, whereas the decrease of anteversion represented external rotation.

RESULTSThe maximum anteversion of the fracture sides, whereas 48 degrees, the minimum anteversion -10 degrees, the mean value, 15.04 degrees, and the standard error is 11.34 degrees. The maximum anteversion of the contralateral side, whereas 31.3 degrees, minimum -4.8 degrees, the mean value was 13.96 degrees and the standard error was 10.20 degrees (P < 0.001). Compared with the contralateral side, half of the 36 cases showed increased anteversion and the other half decreased anteversion. The mean value of internal rotation is 11.56 degrees, and external rotation 9.39 degrees. The maximum internal rotation was 37 degrees, the minimum 0.9 degrees. Eight cases had internal rotation less than 8 degrees, 6 between 10 degrees - 15 degrees, and 4 over 15 degrees. The maximum external rotation was 24.3 degrees, and the minimum 1.8 degrees. Eleven cases had external rotation less than 10 degrees, 4 between 10 degrees - 15 degrees and 3 over 15 degrees. The incidence of malrotation more than 10 degrees was 47% (17/36), and more than 15 degrees 19.4% (7/36).

CONCLUSIONThe incidence of malrotation after femoral shaft fracture treated with close reduction and interlocking intramedullary nailing is high. Attention should be paid to clinical management and strict control for rotational reduction intra-operatively.