UniCAP offers a long term treatment for middle-aged patients, who are not revised within the first 9 years
The aim of this study was to investigate the long-term outcome of the unicompartmental knee resurfacing prosthesis (UniCAP) using clinical and radiographic assessments, and to evaluate the revision and survival rates.
This was a prospective cohort study of patients with UniCAP prostheses with 6–9 years of 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) grading scale. A comparison analysis of the clinical preoperative and follow-up data and a Kaplan–Meier survival analysis were performed.
Of the 64 UniCAP patients, 36 (56%) were revised and one died. Examinations were performed on 23 (85%) of them. When compared with the preoperative data, the examinations showed a significant increase in the KSS objective [mean = 47.4, standard deviation (SD) = 5.8 vs. mean = 90.0, SD = 6.9] and function (mean = 46.7, SD = 6.8 vs. mean = 91.1, SD = 6.9) scores, a decrease in the VAS-score (mean = 7.3, SD = 0.5 vs. mean = 3.4, SD = 1.4) and a significant increase in the KL medial score (mean = 1.7, SD = 0.6 vs. mean = 2.1, SD = 0.5). The Kaplan–Meier survival rate after 5 years indicated good long-term outcomes.
There was a survival rate of approximately 40% after 9 years of follow-up, but in the group of patients (35–65 years old) not eligible for a final total arthroplasty. These patients were often left with pain and disability. This implant can be a temporary or even long-term treatment because it improved the disability and function over the long-term without a major progression in the osteoarthritis, function or pain. Long term results of this mini-prosthesis have not been previously reported.
Level of evidence
KeywordsCondylar implant Femoral resurfacing Cartilage injury Large cartilage lesions Early osteoarthritis Small implants Knee prosthesis
There is no funding source.
Compliance with ethical standards
Conflict of interest
There have been no conflicts of interests.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
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