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Journal of Bone and Joint Surgery - British Volume, Vol 90-B, Issue 9,
1180-1185.
doi: 10.1302/0301-620X.90B9.20298 Copyright © 2008 by British Editorial Society of Bone and Joint Surgery Evaluation of impingement of the anterior tibial post during gait in a posteriorly-stabilised total knee replacementS. Hamai, MD, PhD, Orthopaedic Surgeon1; H. Miura, MD, PhD, Orthopaedic Surgeon, Associate Professor1; H. Higaki, PhD, Mechanical Engineer, Professor2; T. Shimoto, PhD, Mechanical Engineer2; S. Matsuda, MD, PhD, Orthopaedic Surgeon, Assistant Professor1; and Y. Iwamoto, MD, PhD, Orthopaedic Surgeon, Professor and Chairman1
1 Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. Correspondence should be sent to Associate Professor H. Miura; e-mail: miura{at}ortho.med.kyushu-u.ac.jp
Mechanical failure because of wear or fracture of the polyethylene tibial post in posteriorly-stabilised total knee replacements has been extensively described. In this study of 12 patients with a clinically and radiologically successful NexGen LPS posteriorly-stabilised prosthesis impingement of the anterior tibial post was evaluated in vivo in three dimensions during gait using radiologically-based image-matching techniques. Impingement was observed in all images of the patients during the stance phase, although the NexGen LPS was designed to accommodate 14° of hyperextension of the component before impingement occurred. Impingement arises as a result of posterior translation of the femur during the stance phase. Further attention must therefore be given to the configuration of the anterior portion of the femoral component and the polyethylene post when designing posteriorly-stabilised total knee replacements.
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