Computational modelling of hip resurfacing arthroplasty investigating the effect of femoral version on hip biomechanics

Aim How reduced femoral neck anteversion alters the distribution of pressure and contact area in Hip Resurfacing Arthroplasty (HRA) remains unclear. The purpose of this study was to quantitatively describe the biomechanical implication of different femoral neck version angles on HRA using a finite element analysis. Materials and methods A total of sixty models were constructed to assess the effect of different femoral neck version angles on three different functional loads: 0°of hip flexion, 45°of hip flexion, and 90° of hip flexion. Femoral version was varied between 30° of anteversion to 30° of retroversion. All models were tested with the acetabular cup in four different positions: (1) 40°/15° (inclination/version), (2) 40°/25°, (3) 50°/15°, and (4) 50°/25°. Differences in range of motion due to presence of impingement, joint contact pressure, and joint contact area with different femoral versions and acetabular cup positions were calculated. Results Impingement was found to be most significant with the femur in 30° of retroversion, regardless of acetabular cup position. Anterior hip impingement occurred earlier during hip flexion as the femur was progressively retroverted. Impingement was reduced in all models by increasing acetabular cup inclination and anteversion, yet this consequentially led to higher contact pressures. At 90° of hip flexion, contact pressures and contact areas were inversely related and showed most notable change with 30° of femoral retroversion. In this model, the contact area migrated towards the anterior implant-bone interface along the femoral neck. Conclusion Femoral retroversion in HRA influences impingement and increases joint contact pressure most when the hip is loaded in flexion. Increasing acetabular inclination decreases the area of impingement but doing so causes a reciprocal increase in joint contact pressure. It may be advisable to study femoral neck version pre-operatively to better choose hip resurfacing arthroplasty candidates.

Return to Sport After Hip Resurfacing Arthroplasty

Background: Femoroacetabular impingement and degenerative hip osteoarthritis (OA) affect athletes across a wide variety of sports. Hip resurfacing arthroplasty (HRA) has emerged as a surgical treatment for active individuals with end-stage hip OA to provide pain relief and allow return to high-impact activities. Return to professional sports after HRA has not been well characterized. Purpose/Hypothesis: The aim of this study was to report on a series of elite athletes in a variety of sports who underwent HRA. We hypothesized that professional and elite-level athletes would be able to return to sports after HRA for end-stage hip OA. Study Design: Case series; Level of evidence, 4. Methods: A retrospective case series was conducted on professional athletes who underwent HRA at a single institution between 2007 and 2017. All surgeries were performed by a single surgeon using the posterolateral approach. Athletes’ return to play and sport-specific performance statistics were obtained using self-reported and publicly available data sources. Athletes were matched to an age- and performance-based cohort to determine changes in performance-based metrics. Results: Eight professional athletes were identified, including 2 baseball pitchers, 1 ice hockey defenseman, 1 foil fencer, 1 men’s doubles tennis player, 1 basketball player, 1 ultramarathoner, and 1 Ironman triathlete. All 8 patients returned to sports; 6 of 8 (75%) patients were able to return for at least 1 full season at a professional level after surgery. There were no significant differences between performance statistics for athletes who returned to play and their preoperative performance measures for the years leading up to surgery or the age- and performance-matched cohort. Conclusion: HRA remains a surgical alternative for end-stage hip OA in young, high-impact, active patients. While the primary goals of surgery are pain control and quality of life improvement, it is possible to return to elite-level sporting activity after HRA.

Living with a recalled implant: a qualitative study of patients’ experiences with ASR hip resurfacing arthroplasty

Background Total hip arthroplasty is the traditional treatment for osteoarthritis in the hip joint. Hip resurfacing arthroplasty, with metal on metal bearing, is a modern concept initially developed mainly for young active people. The metal-on-metal hip arthroplasty implant, Articular Surface Replacement (ASR), was implanted in approximately 93,000 patients before it was recalled in 2010 due to a high complication rate. This study aimed to evaluate patients’ own experiences living with an implant that they knew had a high complication rate and had been recalled from the market. Methods A total of 14 patients, still living with the implant, of a cohort of 34 patients were available for follow-up. Qualitative semi-structured interviews were conducted with 14 patients where a majority actively sought for metal-on-metal hip resurfacing arthroplasty (HRA), and subsequently underwent HRA with an ASR prosthesis between 11/21/2006 and 09/28/2009. The responses were analyzed using content analysis described by Graneheim and Lundman to compress text and identify categories and subcategories. Results The results showed that most patients had already decided that they wanted a metal-on-metal HRA implant before meeting the surgeon. They expressed that the implant made it possible to live an active life. A majority did not think about the fact that they had a hip implant, because they lacked subjective pain. Most of the patients were positive about the annual exams at the hospital and wanted them to continue. None of them felt that their trust towards the healthcare system had changed after the implant recall. They expressed a belief that they would need new surgery sooner than they first thought. Conclusions Despite all the attention when the ASR prosthesis was recalled, patients with ASR-HRA did not report themselves negatively affected by the recall in this group of patients where a majority had actively sought for an HRA procedure. The healthcare system has an obligation to continue the annual exams, even if the implant provider does not continue reimbursement.