Robotic-assisted conversion of unicompartmental to total knee arthroplasty: a systematic review

Conversion of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA) presents technical challenges due to bone loss and altered anatomy, often requiring stems or augments. Robotic-assisted systems have emerged as a potential solution by improving precision and bone preservation. This systematic review evaluates robotic assistance in UKA-to-TKA conversion and its impact on surgical performance and outcomes. This review followed PRISMA guidelines and was registered in PROSPERO (CRD42025643211). A systematic search of PubMed, Embase, and Scopus was conducted through October 2025. Eligible studies reported outcomes of robotic-assisted UKA-to-TKA conversions with a mean follow-up of 20.9 months. Two reviewers independently screened studies and extracted data on demographics, perioperative variables, functional outcomes, complications, and implant survivorship. Risk of bias was assessed using the ROBINS-I tool. Five studies including 136 patients (140 knees) were analyzed. Most cases (n = 105) used the MAKO SmartRobotics™ System, while the remainder (n = 35) used the ROSA Knee System. No intraoperative conversions to manual technique occurred. Augments were required in 13.6% of cases and stems in 3.6%. Range of motion improved to 119-130° flexion with full extension. Patient-reported outcomes demonstrated improvements in r-WOMAC and OKS, with favorable postoperative FJS. Complication rates ranged from 0 to 11%, including one intraoperative tibial fracture (0.7%), two periprosthetic joint infections, three stiffness cases, and one aseptic loosening. Implant survivorship ranged from 93.2% to 100% at up to 3.6 years follow-up. Robotic-assisted UKA-to-TKA conversion demonstrates reproducible intraoperative performance, minimal need for augments, and favorable short-term outcomes. Longer-term studies are needed to confirm durability.Level of evidence: Level IV.