抄録
Objective: Recently, the number of total knee arthroplasty (TKA) procedures has increased and this has led to an increase in the number of patients requiring revision TKA. The importance of preoperative planning in revision TKA is well known; however, it is difficult to use X-ray film during preoperative planning. Three-dimensional templating software called Athena has been reported to be useful in primary TKA. However, it is unclear whether Athena is useful as preoperative planning software in revision TKA. We investigated this theme using X-ray film and computed tomography (CT) images of inserted implants. We also report a case in which Athena was useful in revision TKA.
Methods: From October to December 2008, we investigated ten knees of seven patients who had undergone primary total knee arthroplasty, taking X-ray and CT images after surgery with a provided specific marker. We measured the resected bone thickness of bilateral distal femur and posterior condyles without cartilage and compared these bone thicknesses to the calculated thickness of the same sites; the implant positions were simulated postoperatively using Athena.
Results: Absolute values of the resected bone thickness from the calculated thickness of the medial and lateral distal femur were 1.4±0.36 and 0.9±0.20 mm, respectively. The absolute values of medial and lateral posterior condyles were 1.7±0.45 and 1.7±0.46 mm, respectively.
Conclusion: The absolute values of resected bone thickness from the calculated thickness in Athena were less than 2 mm in distal femur and posterior condyles. Our data has proved the satisfactory accuracy of Athena using X-ray film and CT images of inserted implants. We also experienced the preoperative planning of revision TKA using Athena. The epicondylar axis was identified and the rotational angle and position of the existing femoral component were evaluated. We were able to evaluate the joint line, with or without bone defects, and determine the necessity of an augmentation block in the femoral component. We concluded that Athena can be very useful in revision TKA as preoperative planning software.
