Eighty patients with bi-compartmental knee osteoarthritis (OA) were randomized to receive a robotic-assisted bi-unicompartmental knee arthroplasty (bi-UKA) (n=42) or a traditional, mechanically-aligned total knee arthroplasty (TKA) (n=38). The outcomes of interest included component positioning and anatomy of the knee joint (femoral and tibial coronal and sagittal angles, femoral and tibial axial angles), as well as the overall hip-knee-ankle (HKA) angle. Outcomes were assessed at 3 months post-operation. Results demonstrated that the change in joint anatomy was statistically significantly lower in the bi-UKA group in all 3 planes in both the femur and tibia (p<0.01 for all), with the exception of the femoral sagittal angle and tibial lateral sagittal angles (p>0.05 for both). The change in HKA angle was statistically significantly smaller in the bi-UKA group compared to the TKA group (p=0.001). Moreover, statistically significantly more patients in the bi-UKA reported less than 2 degree of change in the 6 alignment parameters (p=0.045).