Implant position in knee surgery: a comparison of minimally invasive, open unicompartmental, and total knee arthroplasty.

This is a retrospective radiographic analysis of implant position in minimally invasive unicompartmental knee arthroplasty (UKA), open UKA, and total knee arthroplasty (TKA). Implant position and limb alignment were recorded in the AP and lateral planes. Of the 3 groups evaluated, the total knee group had the least variation and greatest accuracy of implant placement and limb alignment. UKA groups had small but significant differences in postoperative alignment and AP tibial position. Using contemporary instrumentation, UKA is less accurate than TKA in implant placement and limb alignment. Minimally invasive UKA was not as accurate as open UKA in AP tibial placement or postoperative limb alignment.