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Journal of Bone and Joint Surgery - British Volume, Vol 89-B, Issue 11,
1528-1533.
doi: 10.1302/0301-620X.89B11.18834 Copyright © 2007 by British Editorial Society of Bone and Joint Surgery The variation in medial and lateral collateral ligament strain and tibiofemoral forces following changes in the flexion and extension gaps in total knee replacementA LABORATORY EXPERIMENT USING CADAVER KNEESB. Jeffcote, BMBS, FRACS(Orth), Orthopaedic Surgeon1; R. Nicholls, PhD, Research Fellow2; A. Schirm, MD, Orthopaedic Surgeon3; and M. S. Kuster, MD, PhD, FRACS(Orth), Chairman, Professor3
1 Department of Orthopaedic Surgery Correspondence should be sent to Professor M. S. Kuster; e-mail: Markus.Kuster{at}kssg.ch
Achieving deep flexion after total knee replacement remains a challenge. In this study we compared the soft-tissue tension and tibiofemoral force in a mobile-bearing posterior cruciate ligament-sacrificing total knee replacement, using equal flexion and extension gaps, and with the gaps increased by 2 mm each. The tests were conducted during passive movement in five cadaver knees, and measurements of strain were made simultaneously in the collateral ligaments. The tibiofemoral force was measured using a customised mini-force plate in the tibial tray. Measurements of collateral ligament strain were not very sensitive to changes in the gap ratio, but tibiofemoral force measurements were. Tibiofemoral force was decreased by a mean of 40% (SD 10.7) after 90° of knee flexion when the flexion gap was increased by 2 mm. Increasing the extension gap by 2 mm affected the force only in full extension. Because increasing the range of flexion after total knee replacement beyond 110° is a widely-held goal, small increases in the flexion gap warrant further investigation.
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