A comparison of radiographic leg-length and offset discrepancies between 2 intraoperative measurement techniques in anterior total hip arthroplasty

Abstract

Background: Anterior total hip arthroplasty (THA) allows the use of intraoperative fluoroscopy to assess leg-length and offset discrepancies. Two techniques to accomplish this are the transverse rod method and the radiographic overlay method. The aim of this study was to determine if they are equally effective options for minimizing postoperative radiologic discrepancies. Methods: We completed a retrospective cohort study comparing 106 anterior THAs from 1 surgeon using the transverse rod technique to 94 anterior THAs from another surgeon using the radiograph overlay technique. Radiographic leg-length discrepancy (LLD) and offset discrepancy (OD) were measured independently on postoperative radiographs. Parametric, nonparametric, and categorical statistical tests were used to compare LLD and OD between groups. Results: Baseline characteristics were similar between groups. The mean LLD of 4.8 mm in the radiograph overlay group was not significantly different from the 4.4 mm mean discrepancy in the transverse rod group (P = .424), and the rates of LLD < 5 mm and LLD < 10 mm were not significantly different (P = .772, P = .179). The mean OD of 5.1 mm in the radiograph overlay group was not significantly different from the 4.8 mm mean discrepancy in the transverse rod group (P = .668), and there was no significant difference in the rates of OD < 5 mm and OD < 10 mm (P = .488, P = .878). Conclusions: There was no difference between the measured LLD and OD by the 2 surgeons, suggesting that the techniques are equally effective options. Keywords: Anterior total hip arthroplasty, Leg-length discrepancy, Offset discrepancy, Surgical technique