Closer to Native, Not Clinically Superior: Bi-Unicompartmental versus Total Knee Arthroplasty for Bicompartmental Femoro-Tibial Osteoarthritis, A Randomized Trial
In brief
Bi-unicompartmental knee replacement shows no 24-month advantage over total replacement
In an exploratory randomized trial of 56 carefully selected patients, bi-unicompartmental and total knee replacement produced similar patient-reported outcomes at 24 months, including pain and joint awareness. No major complications, reoperations, or revisions were documented in either group, but the small trial and short follow-up leave implant durability and longer-term revision risk unknown.
- Journal
- The Journal of arthroplasty (Q1)
- Published
- 7 October 2026
- Study design
- Randomized controlled trial
- Evidence level
- Level 1, High (CEBM 1b)
- Authors
- Mohammad Mahdi Sarzaeem, Ali Ghanei, Farzad Amouzadeh Omrani, Hamidreza Jamshidi Kouhsari, Gholamhosein Kazemian, Mohammadreza Dolikhani, et al.
- PMID
- 42843679
- DOI
- 10.1016/j.arth.2026.09.050
Why clinicians should know about it
- Picked for Orthopedics and Sports Medicine (paper of the day, 8 October 2026): Bi‑UKA vs CR‑TKA randomized trial for bicompartmental OA
Abstract
BACKGROUND: Bi-unicompartmental knee arthroplasty (Bi-UKA) has been proposed as an alternative to cruciate-retaining total knee arthroplasty (CR-TKA) for patients who have bicompartmental femoro-tibial osteoarthritis. However, comparative evidence remains limited. This study compared patient-reported outcomes at 24 months after simultaneous Bi-UKA and CR-TKA. METHODS: This exploratory randomized clinical trial was conducted at a tertiary center in Tehran, Iran. Patients who had severe bicompartmental femoro-tibial osteoarthritis, clinically and radiographically intact anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL), and absent or minimal patello-femoral involvement were considered eligible. Final eligibility was confirmed intraoperatively before randomization. Eligible patients were randomized in a 1:1 ratio to undergo simultaneous Bi-UKA or CR-TKA. Persian-validated patient-reported outcome measures were assessed at baseline and 24 months. The primary outcome was the Forgotten Joint Score (FJS) at 24 months. Final analyses were performed on a per-protocol, complete-case basis and included 26 patients in the Bi-UKA group and 30 patients in the CR-TKA group. RESULTS: There was no statistically significant between-group difference observed in the FJS at 24 months (mean difference [Bi-UKA minus CR-TKA], -4.91 points; 95% confidence interval [CI]: -17.92 to 8.09; P = 0.453). There were no statistically significant between-group differences observed in the Western Ontario and McMaster Universities Osteoarthritis Index, Knee Society Score, Oxford Knee Score, or visual analog scale pain score. A sensitivity analysis using a linear mixed-effects model yielded findings consistent with the primary analysis. There were no major postoperative complications, reoperations, or revisions documented in either group during the 24-month follow-up. CONCLUSION: In this exploratory trial of carefully selected patients who had severe bicompartmental femoro-tibial osteoarthritis, intact ACL and PCL, and absent or minimal patello-femoral involvement, simultaneous Bi-UKA did not demonstrate superior patient-reported outcomes compared with CR-TKA at 24 months. Follow-up beyond 24 months is required to characterize implant durability, revision risk, and survivorship after both procedures.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.