# 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

## TL;DR

This case report shows that a HemiCAP® hip implant survived 11 years without failure in a patient with femoral head osteonecrosis, with successful osseointegration confirmed through radiological and histomorphological analysis.

## Contribution

First long-term histomorphological and radiological evaluation of HemiCAP® implant in femoral head osteonecrosis.

## Key findings

- HemiCAP® implant achieved uneventful osseointegration over 11 years.
- No complications such as subsidence or infection were observed during the follow-up.
- Histomorphological and radiological analysis confirmed successful implant integration.

## Abstract

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.

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.

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.

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.

•First long term histomorphological analysis of hip HemiCAP•HemiCAP provided 11-year survival in femoral head osteonecrosis.•No signs of implant failure were observed over a decade of follow-up.•Implant osseointegration evaluated after conversion to total hip arthroplasty.•Adds rare long-term outcome data to focal hip resurfacing literature

First long term histomorphological analysis of hip HemiCAP

HemiCAP provided 11-year survival in femoral head osteonecrosis.

No signs of implant failure were observed over a decade of follow-up.

Implant osseointegration evaluated after conversion to total hip arthroplasty.

Adds rare long-term outcome data to focal hip resurfacing literature