Robotic arm-assisted unicompartmental knee arthroplasty: high survivorship and good patient-related outcomes at a minimum five years of follow-up

Knee Surg Sports Traumatol Arthrosc. 2021 Oct;29(10):3316-3322. doi: 10.1007/s00167-020-06198-9. Epub 2020 Jul 31.


Purpose: Robotic arm-assisted unicompartmental knee arthroplasty (RA-UKA) has been shown to improve component placement, reduce intraoperative variability, increase patient satisfaction and improve short-term survivorship results. The aim of this retrospective study was to determine the incidence of revision and the clinical performance at a minimum of 5-year follow-up for a cohort of patients who received a medial RA-UKA.

Methods: Between April 2011 and July 2013, a total of 254 patients underwent medial RA-UKA at a single centre. Clinical performance was investigated using the Forgotten Joint Score-12 (FJS-12) and a 5-level Likert scale made of five items to assess joint perception and patient satisfaction. Kaplan-Meier implant survivorship was calculated and reasons for revision were collected. The effect of age, gender and body mass index (BMI) on the probability of reporting high FJS-12 and satisfaction were assessed.

Results: After considering exclusion criteria and loss to follow-up, a total of 216 patients (224 medial RA-UKAs) were assessed at a mean 5.9 years of follow-up. Five RA-UKAs underwent implant revision, resulting in an overall Kaplan-Meier survivorship of 97.8%. Unexplained knee pain (0.9%) was the most common reason for RA-UKA revision. Good-to-excellent FJS-12 scores and high satisfaction levels were reported at mid-term follow-up. Male patients had higher probability of having FJS-12 > 90 (p < 0.05) and high satisfaction levels (p < 0.05).

Conclusions: RA-UKAs demonstrated high survivorship and good-to-excellent patient-reported outcome measures and satisfaction levels at minimum 5-year follow-up. Results for male patients had improved clinical performance when compared to female subjects.

Level of evidence: IV.

Keywords: Mid-term; Robotic arm-assisted; Survival; UKA; Unicompartmental knee arthroplasty.

MeSH terms

  • Arthroplasty, Replacement, Knee*
  • Female
  • Follow-Up Studies
  • Humans
  • Knee Joint / surgery
  • Knee Prosthesis*
  • Male
  • Osteoarthritis, Knee* / surgery
  • Reoperation
  • Retrospective Studies
  • Robotic Surgical Procedures*
  • Survivorship
  • Treatment Outcome