Accurate limb-length equalization during total hip arthroplasty.

A method of equalization of limb lengths during total hip arthroplasty (THA) was developed that uses the concept of precise reproduction of the position of the femur in space (abduction/adduction) by use of a carpenter's level. Precise reproduction of the femoral position allows accurate measurement of the distance between the pelvis and femur before hip dislocation and after trial component placement allowing accurate measurement of the change in the distance between the femur and pelvis. Accordingly, limb length can be maintained or adjusted to match the contralateral side with increased accuracy. A prospective study was performed with 117 consecutive patients undergoing THA to assess the accuracy of an intraoperative limb-length measuring device. Patients were sequentially randomized into two groups. Group A patients underwent THA without the use of the measuring device, and group B underwent THA using the device. Radiographic assessments of limb lengths were measured using the method of Williamson and Reckling. The hips in group B had a statistically significant decrease in limb-length inequality after THA compared with group A (P<.01). Average postoperative limb-length inequality was 8.8 mm and 3.4 mm for groups A and B, respectively. Three (5%) of 58 group B patients and 18 (31%) of 59 group A patients had a radiographic postoperative limb-length inequality >12 mm (P<.01). Eighty-four of group B patients had limb lengths within 6 mm of the contralateral side compared with 30% of group A patients. Twenty-four percent of group A patients and 7% of group B patients had a symptomatic limb-length inequality that required a heel lift (P<.01).