Combined Anteversion Technique for the Modified Hardinge Approach in Cementless Total Hip Arthroplasty

Abstract

Objective: To define the combined anteversion (CA) angle in the modified Hardinge approach, which created an impingement-free range of motion (ROM) and prevented dislocation. Materials and Methods: The femoral stem was prepared first, the anteversion of the femoral stem was determined and recorded. The target angle for acetabular cup abduction was 40 degrees in all cases. Cup anteversion angle was targeted individually close to but not exceed the native acetabular anteversion angle in each case. The hip joint was tested for impingement-free ROM and stability intraoperatively. Results: There were 120 cases with a mean age of 58.7 years (29 to 91, 14.1) and the mean follow-up of 21.8 months (18 to 37). The mean native acetabular anteversion angle was 11.9 degrees (3 to 28 degrees, 5.1). The mean femoral stem anteversion angle was 13.7 degrees (2 to 35 degrees, 7.7) and the mean acetabular cup anteversion angle was 10.2 degrees (−4 to 21 degrees, 3.6). The mean CA angle was 24.2 degrees (9 to 48 degrees, 7.9). The CA angle was within 10 to 40 degrees for 114 of 120 cases (95%). The acetabular cup anteversion angle was within the Lewinnek safe zone for 113 of 120 cases (94.2%). The mean femoral anteversion angle for male and female individuals was 12.16 degrees (2 to 30 degrees, 6.75) and 14.62 degrees (2 to 35 degrees, 8.17) respectively, there was no significant difference (P=0.094). The mean CA angle for male and female individuals was 23.21 degrees (15 to 42 degrees, 6.37) and 24.72 degrees (9 to 48 degrees, 8.6), respectively, which was not significantly different (P=0.310). There was no dislocation. Conclusions: The mean CA angle in the modified Hardinge approach was 24.2 degrees and the effective CA angle for impingement-free ROM and preventing dislocation was between 10 and 40 degrees.