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In situ forces of the anterior and posterior cruciate ligaments in high knee flexion: An in vitro investigation
Author(s) -
Li Guoan,
Zayontz Shay,
Most Ephrat,
DeFrate Louis E.,
Suggs Jeremy F.,
Rubash Harry E.
Publication year - 2004
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1016/s0736-0266(03)00179-7
Subject(s) - knee flexion , anterior cruciate ligament , hamstring muscles , hamstring , biomechanics , anatomy , medicine , materials science , orthodontics , physical medicine and rehabilitation
The function of the anterior and posterior cruciate ligaments (ACL and PCL) in the first 120° of flexion has been reported extensively, but little is known of their behavior at higher flexion angles. The aim of this investigation was to study the effects of muscle loads on the in situ forces in both ligaments at high knee flexion (> 120°). Eighteen fresh‐frozen human knee specimens were tested on a robotic testing system from full extension to 150° of flexion in response to quadriceps (400 N), hamstrings (200 N), and combined quadriceps and hamstrings (400 N/200 N) loads. The in situ forces in the ACL and PCL were measured using the principle of superposition. The force in the ACL peaked at 30° of flexion (71.7 ± 27.9 N in response to the quadriceps load, 52.3 ± 24.4 N in response to the combined muscle load, 32.3 ± 20.9 N in response to the hamstrings load). At 150°, the ACL force was approximately 30 N in response to the quadriceps load and 20 N in response to the combined muscle load and isolated hamstring load. The PCL force peaked at 90° (34.0 ± 15.3 N in response to the quadriceps load, 88.6 ± 23.7 N in response to the combined muscle load, 99.8 ± 24.0 N in response to the hamstrings load) and decreased to around 35 N at 150° in response to each of the loads. These results demonstrate that the ACL and PCL carried significantly less load at high flexion in response to the simulated muscle loads compared to the peak loads they carried in response to the same muscle loads at other flexion angles. The data could provide a reference point for the investigation of non‐weight bearing flexion and extension knee exercises in high flexion. Furthermore, these data could be useful in designing total knee implants to achieve high flexion. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.