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The Anterolateral Ligament & the Lateral Meniscus’ Synergistic Contribution to Rotational Knee Stability
Author(s) -
Corbo Gillian Gabriela,
Lording Tim,
Burkhart Timothy,
Johnson Marjorie,
Getgood Al
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.231.4
Subject(s) - anterolateral ligament , tibia , anterior cruciate ligament , femur , cadaveric spasm , lateral meniscus , meniscus , medicine , anatomy , acl injury , orthodontics , surgery , anterior cruciate ligament reconstruction , physics , incidence (geometry) , optics
The anterolateral ligament (ALL) is an extra‐capsular structure running from the lateral femoral epicondyle to the lateral aspect of the tibia and lateral meniscus. ALL injury has been reported to contribute to high‐grade anterolateral laxity following anterior cruciate ligament (ACL) injury. Failure to address ALL injury has been suggested as a cause of persistent rotational laxity following ACL reconstruction. Due to the ALL's anatomic connection to the lateral meniscus, recent evidence also suggests that the ALL can be divided into two parts: supra‐ & infra‐meniscal. In addition to ALL tears, lateral meniscus posterior root (LMPR) tears have been shown to cause increased internal rotation and anterior translation of the knee. The literature has yet to examine the ALL in conjunction with the LMPR, therefore the objective of this study was to determine the role of the ALL & LMPR in controlling anterolateral rotational laxity in an ACL deficient knee. Methods 16 fresh frozen cadaveric knee specimens (mid –femur to mid‐tibia) were potted into a hip simulator (femur) and a six degree‐of‐freedom load cell (tibia). Optical trackers inserted into the bone tracked the motion of the tibia with respect to the femur. Biomechanical testing involved applying a 5Nm internal rotation moment to the tibia while the knee was in full extension and tested sequentially in the following three conditions: i) ACL intact ; ii) Partial ACL injury (ACL ant ) –anteromedial bundle sectioned; iii) Full ACL injury (ACL full ). The specimens were then randomized to either have the ALL sectioned first (ALL sec ) followed by the LMPR sec or vice versa. Internal rotation and anterior translation of the tibia with respect to the femur were calculated. A mixed two‐way (3 serial sectioning conditions by 2 ALL section orders) repeated measures ANOVA (α = 0.05) was performed. Results Compared to the ACL intact condition, internal rotation was found to be 1.78° (p=0.026), 3.74° (p=0.001), and 3.84° (p=0.001) greater following ACL full , LMPR sec and ALL sec respectively. LMPR sec and ALL sec resulted in approximately 2° of additional internal rotation (p=0.044 and p=0.010, respectively) compared with the ACL deficient knee (ACL full ). No difference was observed between the ALL and LMPR sectioned states or whether the ALL was sectioned before or after the LMPR (p=0.160). A trend of increasing anterior translation was observed when the 5Nm internal rotation moment was applied up until the ACL was fully sectioned; however, these differences were not significant (p=0.070). Discussion The ALL and LMPR appear to have a synergistic relationship with the ACL in controlling anterolateral rotational laxity. High‐grade anterolateral laxity following ACL injury may be attributed to injuries of the ALL and/or the LMPR. During ACL reconstruction, the posterior roots of both menisci should be inspected carefully to rule out concomitant injury, and if found, should be addressed surgically to aid in stability. Future testing is aimed at determining the tensile properties of the supra‐ & infra‐meniscal parts of the ALL to better understand the capacity they have to control rotation of the knee. Support or Funding Information NSERC & CIHR