Total hip arthroplasty (THA) is one of the most successful and commonly performed surgical interventions worldwide. Based on registry data, at one-year post THA, implant survivorship is nearly 100% and patient satisfaction is 90%. A novel, porous coated acetabular implant was introduced in Europe and Australia in 2007. Several years after its introduction, warnings were issued for the system when used with metal-on-metal bearings due to adverse local tissue reaction, with one study reporting a 24% failure rate (Dramis et al. 2014). A subsequent 2018 study by Teoh et al. showed that the acetabular system had a survival rate of 98.9% at five years when used with conventional polyethylene or ceramic bearing surfaces. The current study was conducted to determine the safety and effectiveness of the acetabular system using standard highly-crosslinked polyethylene (XLPE) and ceramic liners at five-year follow-up. Our hypothesis was that the acetabular system would exhibit survivorship comparable to other acetabular components on the market at five-year follow-up.

A prospective, non-randomized study was conducted from February 2009 to June 2017 at eight sites in Canada and the USA. One hundred fifty-five hips were enrolled and 148 hips analyzed after THA indicated for degenerative arthritis. At five-year follow-up, 103 subjects remained for final analysis. All patients received a zero, three, or multi-hole R3 acetabular shell with Stiktite porous coating (Smith & Nephew, Inc., Memphis, TN, USA). Standard THA surgical techniques were employed, with surgical approach and either of a XLPE or ceramic bearing surface chosen at the discretion of the surgeon. The primary outcome was revision at five-years post-op with secondary outcomes including the Harris Hip Score (HHS), Hip Disability and Osteoarthritis Outcome Score (HOOS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), radiographic analysis, and post-operative adverse events. Data and outcomes were analyzed using summary statistics with 95% confidence intervals, t-tests, and Wilcoxon Rank tests.

At five-year follow-up the overall success rate was 97.14% (95% CI: 91.88–100). When analyzed by liner type, the success rate was 96.81% (95% CI: 90.96–99.34) for polyethylene (n=94) and 100% (95% CI: 71.51–100) for ceramic (n=11), with no significant difference between either liner type (p=1). There were three revisions during the study (1.9%), two for femoral stem revision post fracture, and one for deep infection. The HHS (51.36 pre-op, 94.50 five-year), all 5 HOOS sub-scales, and WOMAC (40.9 pre-op, 89.13 five-year) scores all significantly improved (p < 0 .001) over baseline scores at all follow-up points. One (0.7%) subject met the criteria for radiographic failure at one-year post-op but did not require revision. Six (1.8%) of the reported adverse events were considered related to the study device, including four cases of squeaking, one bursitis, and one femur fracture.

Results from this five-year, multicenter, prospective study indicate good survivorship for this novel, porous coated acetabular system. The overall survivorship of 97.14% at five-year follow-up is comparable to that reported for similar acetabular components and aligns with previous analyses (Teoh et al. 2018).

Introduction

The Direct Anterior Approach (DAA) offers potential advantages of quicker rehabilitation compared to posterior approach THR. The aim of this study was to compare hospital based and early clinical outcomes between these two groups with utilisation of Enhanced Recovery After Surgery (ERAS) protocol.