The purpose of the present study was to compare functional outcomes of medial unicompartmental knee arthroplasty (UKA) in patients with patellofemoral osteoarthritis (PF OA) and those without PF OA and to evaluate the effect of PF OA on functional outcomes after UKA.
The outcomes of 48 knees in patients without PF OA who underwent medial UKA (non-PF OA group) were compared to the outcomes of 57 knees in patients with PF OA [Kellgren-Lawrence (K-L) grade ≤ 2] who underwent medial UKA (PF OA group) with a median follow-up of 5.4 years (range 3.1-10.2 years). Clinical outcomes including anterior knee pain, HSS scores, radiological parameters, and the progression of patellofemoral osteoarthritis were compared, and their effects on functional outcomes were evaluated at the final follow-up visits.
At final follow-up visits, no significant inter-group difference was found in terms of anterior knee pain (1.9 vs. 1.9 in non-PF OA and PF OA groups, respectively), HSS score, or range of motion. Preoperative anterior knee pain and patellofemoral joint degeneration were found to be unrelated to poor outcome in patients that underwent medial UKA. Furthermore, no correlation was found between any functional outcome variable and chondral lesion pattern.
III.
The result of UKA for medial unicompartmental knee osteoarthritis was excellent regardless of PF OA (K-L grade ≤ 2). Hence, the patients with medial unicompartmental OA combined with a moderate degree of anterior knee pain or patellofemoral arthritis should be viewed as appropriate candidates for medial UKA.