japanese hip society

Background: Two of the hotly debated subjects in hip arthroplasty are the safety of the Hueter anterior approach (HAA) for total hip replacement and the outcome of metal on metal hip resurfacing(MMHR). The purpose of this study was to characterize implant survivorship and safety of MMHR done through the HAA. Methods. This was a retrospective chart review of 555 MMHR done via HAA between Sep 2006-Dec 2015. The cohort included 473 males and 82 females; mean age 49.4±6.9 years and mean BMI 28.1±5.3. Implant survivorship was assessed using Kaplan-Meier curves with endpoint as conversion to THA. Results: At a mean patient follow-up of 8.4 years, survivorship was 95.0 % at 5 years (95% CI: 93.2 - 96.8 years) and 92.5% at 10 years (95% CI: 90.0 – 95.0 years) with males at 96.1% (95% CI: 94.3 – 97.9) and 93.8% (95% CI: 91.1 – 96.5) whereas females had 88.8% (95% CI: 81.9 – 95.7) and 85.6% (95% CI: 77.6 – 93.6) at 5 and 10 years respectively (p= 0.033). There were 37 revisions (7%) at a mean time of 3.3 years (SD 2.7) with a mean age at the time of 48.5 years (SD 6.1 years) of which 6.3% were males and 13.4% were females. The most common indication for revision was aseptic acetabular component loosening (n= 12), followed by aseptic femoral component loosening (n= 7) and pseudotumor (n= 6). Median acetabular inclination angle was 39.1 (IQR 29.7 – 48.5) and femoral stem shaft angle was 137.7 (IQR 130.7 – 144.7). Patient reported outcome measures WOMAC and HOOS scores significantly improved pre-operatively compared to 5-years post-operatively (p<0.05). Conclusions: Patients undergoing MMHR through the HAA can expect excellent outcomes with males having better survivorship than females. Acetabular component positioning and fixation remain common causes of failure and require particular attention especially during the learning curve.