A novel approach for evaluating acceptable intra-operative correction of lower limb alignment in femoral and tibial malunion using the deviation angle of the normal contralateral knee

BackgroundA simple and appropriate approach for evaluating an acceptable alignment of bone around the knee during operation has not yet been reported.MethodsThirty-five men and 35 women presenting with nonunion or malunion of the unilateral femoral shaft were included in the first study. Using the standing scanograph, the contralateral normal lower extremity was measured to determine the normal deviation angle (DA) of the medial malleolus when the medial aspect of the knee was placed in the midline of the body. In the second study, the normal DA from individual patients was used as a reference to evaluate knee alignment during operation in 40 other patients presenting with distal femoral or proximal tibial nonunion or malunion. The clinical and knee functional outcomes of these 40 patients were investigated.ResultsThe average normal DA was 4.2° in men and 6.0° in women (p < 0.001). Thirty-four of the 40 patients presenting with disorders around the knee were followed up for an average of 3.6 years (range, 1.1–6.5 years). Thirty fractures healed with a union rate of 88% and an average union period of 4.2 months (range, 2.5–6.5 months). Ideal knee alignment was maintained in all 30 patients with fracture union. Satisfactory function of the knee was achieved in 28 patients (82%, p < 0.001).ConclusionsUsing a normal DA as a reference may be a feasible and effective technique for evaluating an acceptable alignment of bone around the knee during operation.Levels of evidenceLevel IV, Case series.