Intraoperative measurement technique for improved accuracy of femoral offset and leg length in total hip replacement: a retrospective cohort study

Abstract

Introduction: Restoration of limb length equality and femoral offset is critical for the success of total hip replacement (THR). The purpose of this study was to investigate the efficacy of a novel intraoperative measurement technique in minimizing errors in leg length and offset in THR. Methods: This retrospective cohort study included 50 consecutive patients who underwent THR. All surgeries were performed by the same orthopedic surgeon, using the posterior approach. In all patients, the same technique of intraoperative measurement of the femoral offset and limb length was used, which entailed calculation of the distances between reference points on the ischium, greater trochanter, and the screwdriver. Measurements were collected from radiographic imaging data and surgical reports. Results: The mean preoperative+intraoperative limb length discrepancy was −1.7 mm (SD=5.9), with a range of −8 to +4 mm. The mean postoperative limb length discrepancy was 1 mm (SD=4.3), with a range of −4 to +5 mm. The mean difference between the preoperative+intraoperative and postoperative measurements was 1 mm (P=0.004). The mean preoperative+intraoperative femoral offset was 36.5 mm (SD=5.4), with a range of 29.6 to 47.6 mm. The mean postoperative femoral offset was 40.10 mm, with a range of 30.8 to 50.0 mm. The mean difference between the premeasurement+intrameasurement and the postoperative measurement was 3.6 mm. Conclusion: This study presented an intraoperative measurement technique that is simple, low-cost, and requires minimal equipment. This technique was found to be effective in minimizing errors in femoral offset and leg length after THR.