Robotic-arm assisted versus conventional unicompartmental knee arthroplasty: exploratory secondary analysis of a Randomised Controlled Trial

M. J. G. Blyth, I. Anthony, P. Rowe, M. S. Banger, A. McLean, B. Jones

Research output: Contribution to journalArticlepeer-review

104 Citations (Scopus)
59 Downloads (Pure)


Objectives: This study reports on a secondary exploratory analysis of the early clinical outcomes of an randomised clinical trial comparing Robotic-arm Assisted Uni-compartmental Knee Arthroplasty (UKA) for medial compartment osteoarthritis of the knee compared to Manual UKA performed using traditional surgical jigs. This follows reporting of primary outcomes of implant accuracy and gait analysis that showed significant advantages in the Robotic-arm assisted group.Methods139 patients were recruited from a single centre. Patients were randomised to receive either a manual UKA implanted with the aid of traditional surgical jigs, or a UKA implanted with the aid of a tactile guided Robotic-arm Assisted system. Outcome measures included: American Knee Society Score (AKSS), Oxford Knee Score (OKS), Forgotten Joint Score (FJS), Hospital Anxiety Depression (HAD) Scale, University of California at Los Angeles (UCLA) Activity Scale, SF-12, Pain Catastrophising Scale (PCS), Somatic Disease (Primary care evaluation of mental disorders [PRIME-MD] score), Pain Visual Analogue Scale (VAS), Analgesic use, Patient Satisfaction, complications relating to surgery, 90 day Pain diaries and the requirement for revision surgery.ResultsFrom day 1 post-operation through to week 8 post-operation the median pain scores for Robotic-arm Assisted group were 55.4% lower than those observed in the Manual surgery group (p = 0.040). A greater proportion of patients receiving Robotic-arm Assisted surgery improved their UCLA activity score.At 3 months post-operation, the Robotic-arm Assisted group had better AKSS scores (Robotic median 164 (Quarter 1 131, Quarter 3 178), Manual 143 (Quarter 1 132, Quarter 3 166)), although no difference was noted with the OKS.At 1 year post-operation, the observed differences with the AKSS had narrowed from 21 points to 7 points (p = 0.106) (Robotic median=171 (Quarter 1 153, Quarter 3 179), Manual median=164 (Quarter 1 144, Quarter 3 182 No difference was observed with the OKS, and almost half of each group reached the ceiling limit of the score (OKS > 43).The key factors associated with achieving excellent outcome on the AKSS were a pre-operative activity level > 5 on the UCLA activity score and use of Robotic-arm surgery. Factors associated with a poor outcome were manual surgery and pre-operative depression.Conclusions: Robotic-arm assisted surgery results in improved early pain scores and early function scores in some patient reported outcomes measures, but no difference was observed, at 1 year post operatively. Although improved results favoured the Robotic arm assisted group in active patients (i.e. UCLA > = 5), these do not withstand more stringent multiplicity adjustments.
Original languageEnglish
Pages (from-to)631-639
Number of pages9
JournalBone and Joint Research
Issue number11
Publication statusPublished - 21 Nov 2017


  • UKA
  • robotic
  • RCT
  • unicompartmental knee anthroplasty
  • medial compartment osteoarthritis
  • robotic-arm assisted systems
  • surgery
  • early pain scores
  • early function scores


Dive into the research topics of 'Robotic-arm assisted versus conventional unicompartmental knee arthroplasty: exploratory secondary analysis of a Randomised Controlled Trial'. Together they form a unique fingerprint.

Cite this