Hip resurfacing arthroplasty for osteonecrosis of the femoral head: Implant-specific outcomes and risk factors for failure

Abstract

Background: Hip resurfacing arthroplasty (HRA) may be a suitable option for treating osteonecrosis of the femoral head (ONFH). However, concerns regarding the extent of osteonecrosis, amount of defect under the prosthesis, and implant-related complications remain. This study aimed to report implant-specific outcomes and risk factors for failure of HRA in ONFH.

Methods: A total of 202 HRAs (166 patients) performed by a single surgeon were investigated. The stage, size, and location of ONFH were evaluated using preoperative radiographs and magnetic resonance images. Clinical, radiographic results, and serum metal concentrations of articular surface replacement (ASR) and non-ASR devices were compared. Logistic regression analysis was performed to identify the contributors of failures. The mean follow-up duration was 10.6 years.

Results: Twenty-six hips (12.9%) were operated with Birmingham Hip Resurfacing (BHR), 99 (49.0%) with ASR, and 77 (38.1%) with Conserve Plus. The mean Harris Hip Score improved from 52.1 to 93.2 at the final follow-up (P < 0.001). Revision-free survivorships of non-ASR and ASR implants were 99.0% and 82.4%, respectively (P < 0.001). In multivariate analysis, the use of ASR prosthesis, greater combined necrotic angle, and smaller head size were associated with revision surgery. A large combined necrotic angle was the only independent risk factor for mechanical failure at the femoral side (P = 0.029).

Conclusion: HRA for ONFH using BHR and Conserve Plus implants demonstrated favourable clinical outcomes with high revision-free survival rates at 10 years. However, care should be taken for large necrotic lesions that can lead to femoral neck fracture or aseptic femoral loosening.

The translational potential of this article: This study suggests HRA performed for appropriately selected patients with ONFH can show excellent long-term clinical results. Therefore, HRA should remain as one of the treatment options for ONFH, and further development of HRA implants should be continued.

Keywords: Hip resurfacing arthroplasty; Implant-specific outcome; Mechanical failure; Osteonecrosis of the femoral head; Risk factors.

Fig. 1

Photographs showing the surgical procedure of hip resurfacing arthroplasty (HRA) used for osteonecrosis. (A) The necrotic bone was removed down to the underlying dense, reactive bone. (B) The trial femoral component was applied to determine whether the prosthesis could overlap the surface of the remaining femoral head. (C) Additional drill holes were made to increase stability between the viable bone and the acrylic cement.

Fig. 2

(A) Anteroposterior radiograph of a 34-year-old man with Association Research Circulation Osseous (ARCO) Stage 3B osteonecrosis of the left hip. By using magnetic resonance imaging (MRI), the lesion was classified as Japanese Investigation Committee (JIC) Type C2, and the combined necrotic angle was measured at 316°. (B) Hip resurfacing was performed using the articular surface replacement (ASR) device. The measured cup inclination and anteversion angles were 43.6° and 15.2°, respectively. (C) The patient had progressive groin pain without trauma at 6 years postoperatively. Follow-up radiograph showed a varus tilt of the femoral component. (D) In the revision operation, the femoral implant was loosened without signs of infection or adverse reaction to metallic debris (ARMD). A conversion to cementless total hip arthroplasty was performed.

Fig. 3

Kaplan–Meier survival curves with end points of revision for any reason. Implant survival rate of the non-ASR group (99.0%) [95% confidence interval (CI), 97.0–100%] was significantly higher than that of the ASR group (82.4%) (95% CI, 74.8–90.0%) at 10 years (log rank, P < 0.001). ASR = articular surface replacement.

Fig. 4

Serial serum cobalt concentrations (μg/L) at each postoperative year. The mean concentration was higher in the ASR group at 2 years (P = 0.023). ASR = articular surface replacement.

Fig. 5

Serial serum chromium concentrations (μg/L) at each postoperative year. The mean concentrations were higher in the ASR group at 1 year (P = 0.014) and 2 years (P = 0.021). ASR = articular surface replacement.