Abstract
Introduction
When total knee arthroplasty (TKA) or unicompartmental knee arthroplasty (UKA) was indicated for the patient, it is important to perform the exact preoperative planning. Conventionally we created the plan based on the Xp films and transparent acetate sheets. Recntly, the digital radiographs and templating systems were introduced in hospitals and utilized for the preoperative planning. The purpose of this study is to investigate the accuracy of the digital templating by comparing the size of the implants between those chosen by the planning and those actually selected during the operation.
Materials and methods
We investigated the plans of 715 knees with TKAs and 238 knees with UKAs between 2010 and 2014. There were 89 men and 438 women with average age of 72.1. There were 867 osteoarthritis, 46 rheumatoid arthritis, 39 osteonecrosis and 1 revision TKA. We created the preoperative planning using Electronic Picture and Communication system (PACS) and templating system (Advanced Case Plan 2.2 / Stryker). [Fig. 1] During the operation we have checked the actual femoral and tibial sizes of the implants, and compared them with preoperative plannings.
Results
The exact matching of the sizes of the implants between the planning and the operation with TKAs were 59.4% for the femoral components, 52.7% for the tibial components and 32.4% for both components. [Fig. 2] While those figures with UKAs were 88.7%, 67.6% and 63.0% respectively. [Fig. 3] The matching within 1 size difference of the size of the implants between the planning and the operation were 92.4% with TKAs and 95.8% with UKAs.
Discussion
Our study suggested that the digital templating of the TKAs and UKAs had satisfactory accuracy to use as preoperative planning for the operation. The accuracy was better in femur than that of tibia. The difference of the accuracy indicate the probable presence of the hyperplasia of the medial tibial condyle that we cut off to get good ligamtnt balancing. The accuracy of the UKAs was better than that of TKAs. During UKAs, we initially chose the predicted size of the devise and cut the bone, and then finally select the size of the implant. While during TKAs, we measure the size of the bone and then cut the bone. This difference of the operative procedure may result in the higher accuracy of UKAs. We conclude that digital templating for preoperative planning of TKAs and UKAs had satisfactory accuracy.
