Rotational malalignment after fractures of the femur

Abstract

Rotational malalignment is an important complication of intramedullary nailing for femoral shaft fractures. The deformity is established during the operation, indicating inadequate reduction of the fracture. Little was known about the incidence and clinical implications of femoral malrotation. In a series of 76 patients we found 28% to have rotational malalignment ( 15 ). Patients complain about problems with more demanding activities, like practicing sports. The incidence of malrotation was independent of the type of femoral nail (GK or AO) used or the location of the fracture. External rotational deformities cause significantly more symptoms than internal rotational deformities. Rotational malalignment is usually measured clinically or by computed tomography (CT). CT is currently the method of choice. Our study reveals that the accuracy of the clinical measurements is very poor ( 20 ). Also the accuracy of CT determined rotational malalignment of the femur is questionable. Differences between two measurements of one observer can be 10.8 and between two measurements of different observers 15.6 . The inaccuracy in measuring a CT image is mostly determined by the inaccuracy in drawing the line through the femoral neck. All patients with femoral malrotation tend to compensate towards a normal value of foot rotation, relative to the femoral torsion present. The major part of this compensation takes place at hip level. Patients with an external malrotation experience more difficulties compensating, than patients with an internal malrotation. In vitro, rotational malalignment is completely avoided by using the profile of the contralateral lesser trochanter as a reference. Rotations only up to 4 (2.2 1.5 ) were measured. The American Medical Association's Guide to the Evaluation of permanent Impairment does not differ between external and internal malrotation of the femur when evaluating whole person impairment. This is incorrect and the American Medical Association should consider changing this in their guidelines.