Clinical outcomes, complications, and survivorship for unicompartmental knee arthroplasty versus total knee arthroplasty in patients aged 80 years and older with isolated medial knee osteoarthritis: a matched cohort analysis

Purpose The primary goal of this study is to compare clinical outcomes, complication rate, and survivorship in octogenarians who underwent total knee arthroplasty (TKA) or unicompartmental knee arthroplasty (UKA) by performing a matched cohort analysis. Methods We analyzed 75 medial UKAs performed by a single experienced surgeon. The included cases were matched with 75 TKAs performed during the same study period. Potential TKA matches used identical exclusion criteria. UKAs were age-, gender-, and body mass index (BMI)-matched at the rate of 1 UKA to 1 TKA from our departmental database. Clinical evaluation included the visual analog scale for pain, range of motion (ROM—flexion and extension), Knee Society Score (KSS), and Oxford Knee Score (OKS). Each patient was clinically evaluated on the day before the surgery ( T 0 ) and at two follow-ups at least 12 months ( T 1 ) and 24 months ( T 2 ) after the surgery. For the survivorship, revision was defined as failure of the implant (periprosthetic joint infection, periprosthetic fracture, or aseptic loosening), and survival was based on implant revision or patient death. Undesirable clinical developments that were not present at baseline or that increased in severity after treatment were classified as adverse events. Results The mean age at the time of the surgery was 82.1 ± 1.9 years for UKA and 81.5 ± 1.8 years for TKA ( p = 0.06). The two groups differed in regard to surgical time (UKA 44.9 ± 7.2 min; TKA 54.4 ± 11.3 min; p < 0.001); furthermore, the UKA group showed better function (ROM; flexion and extension) than the TKA group at each follow-up time point ( p < 0.05). Both groups reported a significant improvement in all clinical scores (KSS and OKS) when compared with their preoperative status ( p < 0.05), while no differences were found between the groups at each follow-up ( p > 0.05). The UKA group reported 7 (9.3%) failures, while TKA reported 6 failures. There were no survival differences between the groups ( T 1 : p = 0.2; T 2 : p = 0.5). Overall complication rate was 6% in the UKA group versus 9.75% in TKA ( p = 0.2). Conclusion The UKA and TKA patients had similar clinical outcomes, post-operative range of motion, and survivorship in octogenarians with medial knee osteoarthritis, with comparable complication rate. Both the surgical procedures may be considered in this patient population, but further long-term follow-up is needed. Level of evidence Level III.