A simple method to minimize limb-length discrepancy after hip arthroplasty

Background Limb-length discrepancy is not uncommon after total hip arthroplasty. To minimize such discrepancies, we introduced a simple method to select an appropriate modular head during surgery. Patients and methods We used this method in 45 hips, and compared the outcome with that of a historical control group of 47 hips. Both groups received cementless femoral components with modular heads of 4 different neck lengths. In the study group, we calculated the ideal distance between the center of the modular head and lesser trochanter on a preoperative AP radiograph. During surgery, we measured the actual distance between the center of trial heads and the lesser trochanter with a ruler, and selected the head in which the measured distance was closest to this distance. In the control group, we had selected a modular head based on preoperative planning. Results The study group had a smaller mean postoperative limb-length discrepancy (2 (SD 2) mm) than the controls (7 (SD 4) mm). Interpretation This simple technique reduces limb-length discrepancy after cementless total hip arthroplasty.