The evaluation of the distance between popliteus tendon or LCL footprint and the implant of the TKA using 3D template.

Abstract

Background When the surgeons perform total knee arthroplasty (TKA), PT and LCL iatrogenic injury are worried because those femoral footprints are relatively close to the bone resection lesion. The purpose of this study was to evaluate the distance between PT or LCL footprint and TKA implant using the three-dimensional (3D) template system.Methods Eighteen non-paired formalin fixed cadaveric lower limbs were used. All the surrounded soft tissue except the PT and knee ligaments were removed from the limb. Careful dissection of the PT and LCL was performed, and those femoral footprints were detected. Each footprint was periphery marked with a K-wire. CT scanning of the whole lower limb was then performed. The CT data was analyzed with 3D template system. Simulated models of TKA were Journey II BCS and Persona PS. The area of each footprint, and the length between most distal or posterior point of femur and the edge of each footprint were measured. When the implant model was matched to the CT image, the shortest length between each footprint and the bone resection were evaluated.Results The area of PT and LCL footprint were, 38.7±17.7mm 2 , and 58±24.6mm 2 , respectively. The length between most distal or posterior point of femur and the edge of the PT footprint were 10.3±2.4mm, and 14.2±2.8mm, respectively. The length between most distal or posterior point of femur and the edge of the LCL footprint were 16.3±2.3mm, and 15.5±3.3mm, respectively. When simulated the TKA, the shortest length between PT footprint and bone resection lesion of Journey II BCS and Persona PS were, 4.3±2.5mm, and 3.2±2.9mm, respectively. The shortest length between PT footprint and bone resection lesion of Journey II BCS and Persona PS were, 7.2±2.3mm, and 5.6±2.1mm, respectively. PT footprint was suffered by the bone resection of Journey II BCS TKA in 3 knees, and also by the Persona PS’s bone resection in 9 knees.Conclusion The PT and LCL femoral footprint existed close to the femoral bone resection lesion of the TKA. Careful attention is needed not to injure the PT and LCL in the surgical procedures.