Long-term survival, radiological, and histomorphological evaluation of hip resurfacing arthroplasty (HemiCAP) in the treatment of femoral head osteonecrosis: An 11-year follow-up case report.

Introduction and importance: To the best of our knowledge, the histomorphological and radiological evaluation and long-term survival of osseointegration of the HemiCAP® focal hip resurfacing system in the treatment of femoral head osteonecrosis have not previously been demonstrated. This study presents a case of a patient with femoral head osteonecrosis who underwent HemiCAP® resurfacing arthroplasty, followed by total hip arthroplasty (THA) after 11 years. Radiological and histomorphological assessments were performed on the removed implant. A review of relevant literature is also included. Case presentation: A 54-year-old female with right femoral head osteonecrosis did not respond to three years of conservative treatment and core decompression. In 2013, she underwent HemiCAP® resurfacing. No complications such as subsidence, periprosthetic fracture, femoral neck narrowing, osteolysis, or prosthetic infection were observed over the 11-year follow-up. In 2024, THA was performed due to osteoarthritis progression. The explanted femoral head and implant were analyzed histomorphologically and radiologically. Clinical discussion: This case demonstrates that the HemiCAP® implant achieved uneventful osseointegration over 11 years. These findings, supported by long-term radiological and histomorphometric evaluation, highlight the implant's potential value in joint-preserving surgeries in terms of long-term survival. Conclusion: This case demonstrates that HemiCAP® resurfacing can provide 11-year implant survival without failure. To our knowledge, this is the first report evaluating both radiological and histological osseointegration of a HemiCAP® hip implant after long-term follow-up.