Rationale

While THA has consistently demonstrated excellent long‐term clinical outcomes in patients suffering from end‐stage degenerative joint disease,¹ hip resurfacing has emerged as an alternative option with several potential advantages. By only resurfacing the articulation, a relatively larger head is employed which may improve stability.² Furthermore, hip resurfacing maintains more femoral bone stock,³ thereby facilitating future revision surgery and theoretically preserves each patient’s native anatomy and biomechanics, which may result in improved motion and function. This is especially pertinent to young and active patients wishing to return to physically demanding activities. A comparison of patient‐reported outcome measures between hip arthroplasty and resurfacing is therefore of paramount interest.

Clinical comment

The theoretical advantages of hip resurfacing must be demonstrated clinically through improved patient‐reported outcomes over THA (the current gold standard treatment) before widespread adoption is advocated.

Available literature and quality of the evidence

The majority of studies comparing patient reported outcomes between hip resurfacing and replacement surgery are case‐controls (level III) and report mixed results.⁴–¹¹ Nonetheless, there are four randomized controlled trials (RCTs) (level I) that compare clinical outcomes between hip resurfacing and replacement in relatively young and active patients. Two of these studies compare resurfacing with contemporary nonmetal‐on‐metal total hips,¹²,¹³ while the other two studies compare hip resurfacing with metal‐on‐metal THA.¹⁴,¹⁵

Findings

Focusing our discussion on the available level I evidence, there are two studies that compare hip resurfacing to THA with nonmetal‐on‐metal articulations. Costa et al. randomized 126 patients to receive either hip arthroplasty or resurfacing and reported similar Oxford Hip Scores (mean 38.2, 95% confidence interval [CI]: 35.3–41.0 vs 40.4, 95% CI: 37.9–42.9, respectively) and Harris Hip Scores (HHS; 82.3, 95% CI: 77.2–87.5 vs 88.4, 95% CI: 84.4–92.4, respectively) at 12‐month follow‐up.¹³ Strengths of this study include: adherence to a standardized preoperative assessment and perioperative care pathway for both groups, blinded measurement and assessment of outcomes, low cross‐over rates, excellent follow‐up (95%), and the fact that each patient had the allocated surgery according to the preferred technique of the operating surgeon. While clinical outcomes were similar between the two groups, they were limited to a one‐year follow‐up and may not reflect long‐term results between these two interventions. More recently, Haddad and colleagues reported on the long‐term results of their randomized trial involving 80 patients treated with either cementless THA or a Birmingham hip resurfacing.¹² Similar to Costa’s study, there was no difference in mean Oxford Hip Scores (37.9 ± 0.6 for replacement vs 40.1 ± 0.4 for resurfacing) nor HHS (96 ± 4.2 for replacement vs 97.1 ± 5.1 for resurfacing) at mean follow‐up of 12 years. Nonetheless, the authors report that a higher proportion of patients with a hip resurfacing were running and involved in sport and heavy manual labor after 10 years. The authors suggest an advantageous return to high‐level activity in resurfaced patients, perhaps below the sensitivity threshold of the Oxford and HHS. It must be noted, however, that there was a large amount of crossover in this study where only 24 of the 80 patients actually underwent the treatment to which they were randomized.

There are two RCTs comparing hip resurfacing to metal‐on‐metal THA. Vendittoli et al. randomized 209 hips to undergo resurfacing or replacement with a metal‐on‐metal bearing using a 28 mm head.¹⁴ They demonstrated a marginally better Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score in the resurfacing group (5.7 ± 8.6 for resurfacing vs 9 ± 11.0 for THA) at two‐year follow‐up. Garbuz et al. randomized 107 patients to either hip resurfacing or a large head metal‐on‐metal hip arthroplasty.¹⁵ Exceedingly high metal ion levels discovered in the hip arthroplasty group raised concern for trunnionosis and eventually led to the premature termination of the trial. Similar early failures of large head metal‐on‐metal total hips have been identified from multiple studies and registries leading to the widespread abandonment of these implants.¹⁶

Resolution of clinical scenario

• Current level I evidence does not support a clear clinical benefit in patient‐reported outcome measures following hip resurfacing in comparison to THA.
  
• Nonetheless, hip resurfacing as compared to THA may offer advantageous long‐term function with respect to specific high‐demand actives such as participation in running sports and manual labor.

Rationale

Higher‐than‐expected revision rates for resurfaced hips have been reported for numerous reasons including femoral neck fractures,¹⁷,¹⁸ implant position,¹⁹ and size,²⁰,²¹ adverse reactions to metal ions,²²,²³ and certain implant designs.²⁴,²⁵ Given the generally young age and high activity level of this patient population, revision is a major concern – albeit revising a hip resurfacing may be easier than a THA due to preserved femoral bone stock. A critical evaluation of survivorship is therefore necessary to guide surgical indications and appropriate patient selection for successful hip resurfacing.

Clinical comment

Notwithstanding potential clinical benefits of hip resurfacing, the survivorship of these implants in comparison to conventional THA remains a critical concern in the young and active patient.

Available literature and quality of the evidence

Numerous case series, cohort studies, and small single‐center RCTs have compared the revision rates between hip resurfacing and replacement as summarized in the systematic review by Marshall et al.² and meta‐analysis performed by Smith et al.²⁶ The former reported an average time to revision was 3.0 years for metal‐on‐metal hip resurfacing (95% CI: 2.95–3.1) versus 7.8 years for THA (95% CI: 7.2–8.3). Similarly, Smith et al. demonstrated a risk ratio for revision of 1.72 (95%CI: 1.20–2.45) with hip resurfacing compared to replacement; however, both Marshall and Smith caution the lack of high‐quality data included in these analyses. Few studies reported medium‐ or long‐term follow‐up or adequate matching of controls, and included a variety of hip resurfacing implants – some of which have been shown to be far more successful than others. Consequently, we believe the data from national joint registries, which collect detailed information on patients undergoing joint replacement, are the best available data on survivorship and will be used in this section to compare revision rates of hip resurfacing and replacement implants.

Findings

The 2016 annual report of the Australian National Joint Replacement Registry analyzes 498 660 primary and revision hip arthroplasty procedures with up to 15‐year follow‐up.²⁷

Related posts:

The Direct Anterior Approach Patient‐Specific Instrumentation in Total Knee Arthroplasty Management of Glenoid Bone Loss Distal Femur Fractures Periprosthetic Fractures: Knee Lisfranc Injuries

Stay updated, free articles. Join our Telegram channel

Join