Comparable outcomes between lateral and medial unicompartmental arthroplasty at 2-year follow-up

Our study sought to evaluate (1) national rates of lateral unicompartmental knee arthroplasty (UKA) relative to medial UKA and compare, (2) 90-day medical complications and (3) 1- and 2-year surgical complications between matched lateral and medial UKA cohorts.

The PearlDiver Mariner database was queried for patients undergoing primary UKA between 2016 and 2022. ICD-10 procedure codes were utilized to segregate patients into lateral and medial compartment cohorts. Patients undergoing bicompartmental-UKA were excluded. Lateral UKA patients were matched 1:4 to the medial UKA cohort based on age, sex, Elixhauser Comorbidity Index (ECI), and the following comorbidities: diabetes, tobacco use, and obesity. Medical complications at 90-days and surgical complications at 1- and 2-years post-operatively were compared utilizing multivariate logistic regression.

Over the study period, medial UKAs were performed at a 14.17 to 1 ratio compared to lateral UKAs. Lateral UKA patients demonstrated a higher incidence of acute periprosthetic joint infection (PJI) at 90-days post-operatively (OR: 3.919, 95% CI: 1.075-14.283; p = 0.033). However, no differences were seen for the remaining medical outcomes. There were no differences in revision for PJI (OR: 2.071, 95% CI: 0.764-5.162; p = 0.192) or in all-cause revision rates (OR: 1.956, 95% CI: 0.973-3.768; p = 0.050) at 2-years.

Although there was a higher rate of PJI in the acute post-operative setting for patients undergoing lateral UKA, the present analysis demonstrates largely comparable outcomes between our studied cohorts. These findings serve to inform adult reconstruction surgeons considering lateral unicompartmental arthroplasty in appropriately selected patients with isolated lateral compartment osteoarthritis of the knee.