Background
Patient-specific instrumentation (PSI) is attracting attention as a mechanical method of ensuring the accuracy of osteotomy during total knee arthroplasty (TKA). Few studies have focused on preoperative plans; thus, it is unclear how often initial plans have to be corrected preoperatively and intraoperatively. We investigated the frequency of corrections, the accuracy of intraoperative osteotomy, and postoperative alignment.