Affiliations: [a] Department of Mechanical Engineering, Yonsei University, Seoul, Republic of Korea | [b] Department of Orthopaedic Surgery, Joint Reconstruction Center, Yonsei Sarang Hospital, Seoul, Republic of Korea
Correspondence:
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Corresponding author: Sae Kwang Kwon, M.D., Department of Orthopaedic Surgery, Joint Reconstruction Center, Yonsei Sarang Hospital, 10 Hyoryeong-ro, Seocho-gu, Seoul, 06698, Republic of Korea. Tel.: +82 2 2023 5541; Fax: +82 2 2023 5597; E-mail: osskkwon@gmail.com
Note: [†] Kyoung-Tak Kang and Yong-Gon Koh contributed equally to this work and should be considered co-first authors.
Abstract: BACKGROUND:The conservation of the joint anatomy is an important factor in total knee arthroplasty (TKA). The restoration of the femoral posterior condylar offset (PCO) has been well known to influence the clinical outcome after TKA. OBJECTIVE:The purpose of this study was to determine the mechanism of PCO in finite element models with conservation of subject anatomy and different PCO of ±1, ±2, ±3 mm in posterior direction using posterior cruciate ligament-retaining TKA. METHODS:Using a computational simulation, we investigated the influence of the changes in PCO on the contact stress in the polyethylene (PE) insert and patellar button, on the forces on the collateral and posterior cruciate ligament, and on the quadriceps muscle and patellar tendon forces. The computational simulation loading condition was deep knee bend. RESULTS:The contact stresses on the PE insert increased, whereas those on the patellar button decreased as posterior condylar offset translated to the posterior direction. The forces exerted on the posterior cruciate ligament and collateral ligaments increased as PCO translated to the posterior direction. The translation of PCO in the anterior direction, in an equivalent flexion angle, required a greater quadriceps muscle force. CONCLUSIONS:Translations of the PCO in the posterior and anterior directions resulted in negative effects in the PE insert and ligament, and the quadriceps muscle force, respectively. Our findings suggest that orthopaedic surgeons should be careful with regard to the intraoperative conservation of PCO, because an excessive change in PCO may lead to quadriceps weakness and an increase in posterior cruciate ligament tension.
Keywords: Posterior condylar offset, total knee arthroplasty, finite element analysis
