Learning curve of robot-assisted total knee arthroplasty and its effects on implant position in Asian patients: A prospective study

Background: Robot-assisted total knee arthroplasty (r-TKA) can reportedly achieve a more accurate implant position than conventional total knee arthroplasty (c-TKA), although its learning curve is controversial. Moreover, there are few studies on Asians with different anatomical characteristics. This study aimed to determine the learning curve for r-TKA and compare implant positions between r-TKA and c-TKA according to the learning curve in Asian patients. Methods This prospective study included 50 consecutive c-TKAs (C group), followed by 50 consecutive r-TKAs using the MAKO robotic system (Stryker, USA). Cumulative summation analyses were performed to assess the learning curve for operative time in r-TKAs. Accordingly, the r-TKA cases were divided into initial cases (I group) and proficiency cases (P group). Femoral and tibial component positions in the coronal, sagittal, and axial planes and lower limb alignment were compared among all groups. Results r-TKA was associated with a learning curve for operative time in 18 cases. Operative time was significantly shorter in the C and P groups than in the I group, with no significant difference between the C and P groups. The I and P groups demonstrated fewer outliers regarding lower limb alignment, femoral component coronal position, axial position, and tibial component sagittal position than the C group, with no significant difference between C and P groups. Conclusion Operative time was not significantly different between r-TKA and c-TKA after the learning curve. Surgeons could expect more accurate and reproducible lower limb alignment and implant position with r-TKA in Asian patients regardless of the learning curve.