HemiCAP Knee Implants: Mid- to Long-Term Results

The aim of the study was to investigate the long-term outcomes of the Focal Femoral Condyle Resurfacing Prosthesis (HemiCAP) using clinical and radiographic assessments, and to evaluate the revision and survival rates.

Clinical evaluation was performed in those not revised and was able to participate. This was a prospective single-center cohort study of HemiCAP patients with 7 to 10 years of clinical and radiographic follow-up. The clinical examination included the Knee Society Score (KSS) and visual analogue scale (VAS) score. The radiographic examination included the Kellgren-Lawrence (KL) grade. Survival was estimated by Kaplan-Meier survival analysis, and potential risk factors for revision was evaluated by a regression analysis.

Of the 62 patients with 64 HemiCAP prostheses, 37 were HemiCAP condyle, 11 HemiCAP PF, and 16 HemiCAP Wave; 27 (42%) were revised-HemiCAP condyle 17 (42%), HemiCAP PF 4 (36%), HemiCAP Wave 6 (37%), and 1 died. Examinations were performed on 31 patients (86%). When compared with the preoperative data, there were significant increases in the KSS objective (mean = 51.5, standard deviation [SD] = 5.9 vs. mean =94.2, SD = 5.0) and function (mean = 51.0, SD = 6.2 vs. mean = 93.7, SD = 4.8) scores, a decrease in the VAS score (mean = 7.1, SD = 0.7 vs. mean = 2.7, SD = 1.7) and a decrease in the KL lateral score (mean = 1.1, SD = 0.3 vs. mean = 0.6, SD = 0.6). The mean follow-up was 7.3 years (SD 1.4) with minimum 4.2 years and maximum 10.2 years. No failures occurred in the series beyond 5 years.

As hypothesized, we found good clinical and radiographic outcomes, and for those patients who did not require revisions, there were long-term improvements in disability and function. This suggests that patient selection is a key element to successfully applying these devices in clinical practice.