Functional improvement of unicompartmental knee arthroplasty compared with total knee arthroplasty for subchondral insufficiency fracture of the knee

Abstract

Background Subchondral insufficiency fracture of the knee (SIFK) causes acute knee pain in adults and often requires surgical management. Unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) are the two most common surgical treatments for SIFK. While both UKA and TKA have their advantages, there is no consensus for SIFK localized on the medial compartment. We hypothesized that patients with SIFK treated with UKA would show superior patient-reported outcomes compared to those who underwent TKA. Methods A total of 90 patients with SIFK were included in the TKA (n = 45) and UKA (n = 45) groups, respectively. SIFK lesions were measured on MR images. Hip knee ankle (HKA) angle was obtained preoperatively and at the final follow-up. Patient-reported outcomes in the form of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Hospital Special Surgery (HSS) scores, and Knee Society Scores (KSS) were assessed preoperatively, post-operative 6, 12 months, and at the final follow-up. Results The UKA group had better range of motion of the knee preoperatively and postoperatively than the TKA group (p<.01 and p<.01). At 6 months, WOMAC score was better in the UKA group than the TKA group (p<.01). Both groups had a significant improvement in WOMAC, HSS, and KSS scores at the final follow-up compared to preoperative scores. There were no surgical complications in the TKA group, but the UKA group had 3 revision cases due to a bearing failure. Conclusion Unicompartmental arthroplasty and total joint arthroplasty can produce successful outcomes in patients with SIFK with proper patient selection, regardless of the size of SIFK lesion.