Mild Coronal Stem Malalignment Does Not Negatively Impact Survivorship or Clinical Results in Uncemented Primary Total Hip Arthroplasties With Dual-Tapered Implants

Background: Proper component positioning in total hip arthroplasty (THA) is crucial for implant fixation and hip stability. The purpose of this study is to assess if neutral coronal stem alignment (0° ± 3°) improved long-term survivorship in uncemented femoral components. Methods: Between 2005 and 2010, 1028 primary THAs were performed with 2 contemporary dual-tapered, proximally coated uncemented stem types. Alignment was measured immediately postoperatively and at most recent follow-up. In total, 978 femoral stems (95%) were within 0° ± 3° of the neutral anatomic coronal axis, and the 50 stems (5%) outside that range were considered outliers (3.1° of valgus to 4.8° of varus). Outcomes analyzed included implant survivorship, Harris Hip Scores, and incidence of dislocation. Mean follow-up was 5 years. Results: Survivorship free of aseptic femoral component loosening was 99.3% and 98.2% at 5 and 8 years in the neutral group vs 100% at 5 and 8 years in the outlier group (P = .98). Survivorship free of femoral component revision for any reason was 99.1% and 97.3% at 5 and 8 years vs 100% at 5 and 8 years, respectively (P = .80). Harris Hip Scores were similar (89 in both groups; P = .84) at most recent follow-up. The incidence of mild to moderate thigh pain was also similar in both groups (6.1% vs 6%, P = .85). The incidence of dislocation was 1.5% at 8 years, and similar between both groups (P = .77). Conclusion: Slight malalignment of contemporary dual-tapered uncemented THA femoral components does not appear to negatively impact survivorship or clinical outcomes, which is in contrast to cemented femoral components. Level of evidence III: Case-control study.