Lateral Unicondylar Knee Arthroplasty with Lateral Parapatellar Incision Returns Athletes to Moderate and Vigorous Sports: 2-11 Year Follow-Up

Abstract

Objectives: Isolated lateral compartment osteoarthritis (OA) accounts for ~10% of all arthritic knees. Improved implant design and durability have increased the use of lateral unicompartmental arthroplasty (UKA) in the treatment of isolated lateral compartment OA, though some suggest lateral UKA results in inferior outcomes compared to medial UKA. We investigate the clinical and functional outcomes after lateral UKA and determine the influence of sporting activities on mid- to long-term outcomes and survivorship of lateral UKA. We hypothesized that all patients will exhibit excellent clinical and functional outcomes at mid- to long-term follow-up with no differences regardless of sporting activities. Methods: Fifty lateral UKA were performed in 46 patients by a single surgeon (2003-2013). A minimum of 2 year follow-up was required for inclusion. Seventeen males and 29 females with an average age of 67±12 years were included. All patients underwent clinical and radiographic evaluation. Pre- and postoperative clinical examination included knee flexion and extension range of motion (ROM) and radiographic evaluation. Subjective questionnaires included Lysholm and HSS scores. Radiographic evaluation included full knee series including standing alignment films to assess for prosthesis wear and progression of osteoarthritis in the contralateral, unoperated compartments. Sports were categorized as moderate or vigorous based on American College of Sport Medicine (ACSM) guidelines. Failure was defined as conversion to TKA. An independent samples t-test was used to assess differences in outcome measures between sports groups. Significance was defined as p˂0.05. Results: Fifteen patients participated in moderate sports (golf, swimming, walking, bowling, cycling, tai chi, dancing, horseback riding, and fishing), 18 patients participated in vigorous sports (tennis, skiing, mountain biking, moguls, hockey, and basketball), and 13 patients did not participate in sports preoperatively. Average follow-up was 5.8±2.1 years (range: 2-11 years). All patients regardless of sporting activity level displayed significantly higher postoperative functional scores compared to preoperative scores (all p<0.05). Patients displayed excellent postoperative functional scores and flexion range of motion with no significant differences between sporting groups (all p<0.05) (Figure). There was one failure in a patient in the moderate sports group (2.2%) and one failure in a patient in the vigorous sports group (2.2%) that occurred at 6 years. Conclusion: We recommend lateral UKA using a lateral parapatellar incision for patients with isolated lateral compartment OA. Intervening earlier in the disease process with a less invasive procedure such as lateral UKA before impairments are magnified and a TKA is necessary may optimize outcomes and allows patients to return to moderate and vigorous sports including tennis, skiing, mountain biking, moguls, hockey, and basketball without negative consequences.