Evaluation of the Length and Isometric Pattern of the Anterolateral Ligament With Serial Computer Tomography

Abstract

Background:Recent anatomical studies have identified the anterolateral ligament (ALL). Injury to this structure may lead to the presence of residual pivot shift in some reconstructions of the anterior cruciate ligament. The behavior of the length of this structure and its tension during range of motion has not been established and is essential when planning reconstruction.Purpose:To establish differences in the ALL length during range of knee motion.Study Design:Descriptive laboratory study.Methods:Ten unpaired cadavers were dissected. The attachments of the ALL were isolated. Its origin and insertion were marked with a 2 mm–diameter metallic sphere. Computed tomography scans were performed on the dissected parts under extension and 30°, 60°, and 90° of flexion; measurements of the distance between the 2 markers were taken at all mentioned degrees of flexion. The distances between the points were compared.Results:The mean ALL length increased with knee flexion. Its mean length at full extension and at 30°, 60°, and 90° of flexion was 37.9 ± 5.3, 39.3 ± 5.4, 40.9 ± 5.4, and 44.1 ± 6.4 mm, respectively. The mean increase in length from 0° to 30° was 3.99% ± 4.7%, from 30° to 60° was 4.20% ± 3.2%, and from 60° to 90° was 7.45% ± 4.8%. From full extension to 90° of flexion, the ligament length increased on average 16.7% ± 12.1%. From 60° to 90° of flexion, there was a significantly higher increase in the mean distance between the points compared with the flexion from 0° to 30° and from 30° to 60°.Conclusion:The ALL shows no isometric behavior during the range of motion of the knee. The ALL increases in length from full extension to 90° of flexion by 16.7%, on average. The increase in length was greater from 60° to 90° than from 0° to 30° and from 30° to 60°. The increase in length at higher degrees of flexion suggests greater tension with increasing flexion.Clinical Relevance:Knowledge of ALL behavior during the range of motion of the knee will allow for fixation (during its reconstruction) to be performed with a higher or lower tension, depending on the chosen degree of flexion.

In Vivo Anterolateral Ligament Length Change in the Healthy Knee During Functional Activities—A Combined Magnetic Resonance and Dual Fluoroscopic Imaging Analysis

“…The non-isometric pattern of the ALL is in agreement with previous in vitro studies, 1, 3, 4 and comparable length change of the ALL to our previous measurements during a quasi-static lunge were observed. 21 Helito et al 3 , found that the ALL increased in length from full extension to 90°, with greater length increase from 60° to 90° than from 0° to 60°.…”

“…2 These findings are directly at odds with findings by others which found the ALL to be non-isometric, and gradually increase in length during 0° to 90° of flexion, its greatest length increase was noticed from 60° to 90° of flexion. 3 Similar non-isometric behavior was found in another independent study group. 4 Possible explanations for the aforementioned differences in length change patterns might be the variability of the femoral attachment of the ALL used for ALL measurement in the cadaveric studies.…”

“…21 Helito et al 3 , found that the ALL increased in length from full extension to 90°, with greater length increase from 60° to 90° than from 0° to 60°. These findings are in agreement with the study by Zens et al 4 , which found the ALL to be a non-isometric structure that increased in length with increasing knee flexion.…”

The meniscal insertion of the knee anterolateral ligament

“…At the time of reconstruction, in addition to the bone attachment points of the ligament on the femur and tibia and knowledge about the ALL isometricity [15], the meniscal attachment may also be important. Biomechanical studies are being conducted to test whether there is a significant function of this insertion in the genesis of anterolateral instability of the knee.…”

Revisión sistemática: ligamento anterolateral de la rodilla

“…Los estudios biomecánicos sobre el LAL más recientes ponen de manifiesto el control de la estabilidad rotacional a grandes ángulos de flexión (9,18,20,21,24,(47)(48)(49) , donde no existiría un pivot shift significativo (se explora a unos 30° de flexión), mientras que otros defienden el control del mismo en extensión y escasos ángulos de flexión (1,(8)(9)(10)13,16,17) , con posibilidad de ser apreciado en el pivot shift, siendo un restrictor secundario en la estabilidad anteroposterior.…”