Lateral unicompartmental knee arthroplasty is associated with nearer-normal gait characteristics and higher patient satisfaction compared to total knee arthroplasty

Aims Lateral unicompartmental arthroplasty (UKA-L) is a bone- and cruciate-preserving procedure in the treatment of isolated lateral compartment gonarthrosis, but relatively little is known of its associated gait characteristics and patient-reported outcomes. Methods A total of 20 individuals, at a mean 35 months (SD 37) post UKA-L, were measured on an instrumented treadmill. They were compared to age-, sex-, and BMI-matched healthy controls (n = 22) and individuals with unilateral total knee arthroplasty (TKA, n = 28) mean 44 months (SD 46) post-surgery (p = 0.382). Top walking speed, temporospatial parameters, and vertical ground reaction forces of gait were analyzed. Oxford Knee Scores (OKS) and EuroQol five-dimension questionnaire (EQ-5D) scores were compared. Results The UKA-L group walked at a mean speed of 7.0 km/hour (SD 0.6), which was 0.2 km/hour (3%) slower than the healthy control group (7.2 km/hour (SD 0.7); p = 0.681) but 26% faster than the TKA group (5.5 km/hour (SD 0.7), p < 0.001). UKA-L displayed nearer normal vertical ground reaction forces throughout the stance phase. TKA demonstrated significantly reduced maximum weight acceptance, increased mid-stance, and reduced push-off forces compared to healthy and UKA-L subjects (all p < 0.05). UKA-L recorded similar step and stride lengths to healthy controls, and were 12% and 10% longer than TKA, respectively (p < 0.05). UKA-L was associated with a mean OKS of 44 (SD 3) compared to 36 (SD 6) for TKA (p < 0.001), and mean EQ-5D of 0.90 (SD 0.09) vs 0.78 (SD 0.14) for TKA (p = 0.003). Conclusion UKA-L restores healthy gait characteristics at top walking speeds. Compared to TKA, faster walking speeds, nearer-normal vertical ground reaction forces, longer stride lengths, and a more consistent gait pattern demonstrate the importance of functional cruciate ligaments to gait. UKA-L is associated with high patient satisfaction and good quality of life in the treatment of isolated lateral compartment arthrosis. Cite this article: Bone Joint Res 2026;15(2):148–156.