Early outcomes in robotic arm-assisted bi-unicompartmental knee arthroplasty compared to total knee arthroplasty: a prospective, randomised controlled trial

Mark J G Blyth, Matthew S Banger, James Doonan, Bryn G Jones, Angus D MacLean, Philip J Rowe

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The objective of this study was to compare early outcomes of robotic-arm assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) to determine any differences in clinical outcomes between the groups from the first 6 weeks until 1 year post-surgery.
A per-protocol analysis of 76 patients (34 bi-UKA and 42 TKA patients) was performed from a prospective, single-centre, randomised controlled trial. Patient diaries (pain, function, analgesic use) were recorded daily throughout week 1, then weekly from weeks 2 to 6. Patient resported outcome measures (PROMs) were compared pre-operatively, and at 3 months and 1 year. Data were additionally compared longitudinally and a subgroup analysis conducted, stratified by pre-operative PROM status.
Both interventions were shown to be effective treatment options, offering comparable outcomes, with no significant differences shown between interventions across all time points and outcome measures. Additionally, both interventions had similarly low frequency of complications. Subgroup analysis for pre-operative psychological state, activity levels, and BMI showed no difference in outcomes between the two types of surgery.
Robotic arm-assisted, cruciate-sparing bi-UKA offers similar early clinical outcomes and complication rates to a mechanically aligned TKA, both in the immediate postoperative period and for up to one year following surgery. Further work is required to identify which patients with osteoarthritis of the knee will derive benefit from a cruciate sparing bi-UKA approach.
Original languageEnglish
Number of pages23
JournalThe Bone and Joint Journal
Publication statusAccepted/In press - 21 May 2021


  • robotic-arm assisted systems
  • total knee arthroplasty
  • surgery recovery

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