Clinical Outcomes and Survivorship of Lateral Unicompartmental Knee Arthroplasty: Does Surgical Approach Matter?

Background: Lateral unicompartmental knee arthroplasty (UKA) has been shown to be an effective procedure to treat isolated lateral compartment osteoarthritis with excellent long-term survivorship. Whether a medial parapatellar approach or a lateral parapatellar approach is superior in lateral UKA is unknown. The purpose of this study was to determine if there is a difference in intermediate-term clinical outcomes in patients undergoing lateral UKA through a lateral vs medial parapatellar approach. Methods: We retrospectively reviewed a consecutive series of 65 patients who underwent lateral UKA with a minimum of 2-year follow-up. Fifty-two patients (80%) had a lateral approach and 13 (20%) a medial parapatellar approach. Patient demographics, preoperative and postoperative radiographic findings, need for revision surgery, Knee Society Score, and range of motion were assessed. Results: Overall survivorship was 94% at amean of 82months; with the sample size available for study, there was nodifference in survivorship between the groups. There was no difference in Knee Society Score or revision to total knee arthroplasty (5% vs 7%, P = 1.000) between themedial and lateral approach groups. Comparatively, the lateral approach group did have significantly greater postoperative flexion (123.6 degrees vs 116.5 degrees, P = .006) and greater improvement in flexion from preoperative measurements (3.0 vs -8.0 degrees, P = .010). Conclusion: Although our sample size was small, we could not demonstrate a difference in revision rates or clinical outcome scores when comparing a lateral or a medial approach with lateral UKA at intermediate-term follow-up. A lateral approach did have greater postoperative flexion, but its clinical significance remains undetermined. (C) 2017 Elsevier Inc. All rights reserved.