Purpose: Historically, there have been few surgical options for patients with focal full-thickness cartilage lesions in the knee who have failed or are too advanced in age for biologic resurfacing treatments, yet are also relatively too young or unwilling to undergo conventional total or unicompartmental knee arthroplasty. The UniCAp knee resurfacing arthroplasty provides an option for these patients that is minimally invasive, preserves the menisci and cruciate ligaments, and retains the bony architecture of the knee joint, thereby providing the potential for a rapid recovery to more vigorous activities than might be permitted after conventional knee arthroplasty, while preserving range of motion. The objective of this study was to examine the clinical results of a patient cohort undergoing the UniCAP knee resurfacing in the medial compartment of the knee.

Method: Prospective patients were screened with history and clinical examination, weight-bearing radiographs, and MRI. Patients were offered UniCap knee resurfacing arthroplasty if they had symptomatic full-thickness cartilage lesions in the medial and/or patellofemoral compartments. The cohort included 38 cases in 35 patients who underwent the UniCAP knee resurfacing procedure in the knee with focal medial compartment (with or without patellofemoral) osteoarthritis in the knee joint. In addition, patients were assessed with validated and established outcome scales including the International Knee Documentation Committee Subjective Form, the Knee Injury and Osteoarthritis Outcome Scale, which includes the WOMAC Osteoarthritis Index.

Results: The average age of patients undergoing knee resurfacing was 48.25 years (Range: 23 to 80). There were 24 males and 12 females. Thirty-one patients underwent isolated medial compartment resurfacing and 7 patients received both a medial compartment resurfacing and trochlear resurfacing. Three patients underwent a concomitant ACL reconstruction and 1 patient underwent a concomitant high tibial osteotomy. The mean duration of follow up was 18 months (Range: 12 to 26 months). There was an overall mean improvement from the pre-operative to post-operative scores in the IKDS-SF (P < 0.01), KOOS (all domains, P < 0.01) and WOMAC Index (P < 0.01). There were no major complications such as deep infection, DVT, or implant failure. In addition, there was no evidence of mechanical symptoms/signs or radiographic evidence of loosening at any time point post-operatively.

Conclusion: The short-term results demonstrate that the UniCAP resurfacing arthroplasty in the knee is a viable treatment option for focal full thickness cartilage lesions in the medial compartment of the knee in patients who are no longer candidates for biologic resurfacing procedures and who are also relatively too young or unwilling to undergo conventional total or unicompartmental knee arthroplasty.