Outcomes and survivorship of unicondylar knee arthroplasty in patients with severe deformity

Purpose Patients with severe deformity beyond the standard indications for unicompartmental knee arthroplasty (UKA) may be suitable and benefit from UKA. This study investigated their outcomes to determine whether good function and quality of life (QOL) can be achieved. Fifty-three patients with severe deformity (40 patients with FFD a >= 15A degrees and 13 patients with varus deformity >= 15A degrees, Group A) were matched with 53 patients with less severe deformities who underwent UKA (Group B/controls) in terms of age, sex, BMI and duration of follow-up. Their flexion range, Knee Society scores (KSS), Oxford knee scores (OKS) and SF-36 QOL scores were analysed pre-operatively and at 2 years. Group A patients were largely similar to Group B patients pre-operatively in terms of maximum flexion angle, OKS and SF-36 scores except for knee score and mental health component of SF-36. At 2 years, Group A reported largely similar results compared with Group B in all outcome scores (OKS, KSS, SF-36) and flexion angle. Post-operative mechanical alignment was better for the control group though it is not statistically significant. There were no revisions in the patients with severe pre-operative deformity at 5 years post-operatively. (Survivorship 100 % at 5 years). Selected patients with severe deformity can achieve good function and QOL with UKA if satisfactory mechanical alignment is restored. This study supports a broadening of the indications of UKA; however, further follow-up is needed to assess the longer-term durability of the operation. IV.