The median anterolateral ligament femoral origin was 10 mm (first interquartile 6 mm, third interquartile 13 mm) distal to the femoral physis, whereas the median tibial insertion was found to be 9 mm (first interquartile 5 mm, third interquartile 11 mm) proximal to the tibial physis (Table 6). The median length of the anterolateral ligament was 33 mm (first interquartile 31 mm, third interquartile 36 mm). The median width at the femoral origin point was 3 mm (first interquartile 2 mm, third interquartile 4 mm), and the median width at the tibial insertion point was 4 mm (first interquartile 3 mm, third interquartile 6 mm).
The anterolateral ligament has been demonstrated to be a rotational stabilizer of the knee [15, 29] and several recent studies have described its anatomy and structure in adults [1-3, 6, 9, 10, 18, 20]. However, the presence and anatomy of the anterolateral ligament in the pediatric population are not well described. The current study identified the anterolateral ligament in eight of 14 specimens, which demonstrated considerable variation in the anterolateral ligament's anatomic relationship to the lateral collateral ligament and a close relationship between the anterolateral ligament femoral origin and the distal femoral physis.
This study has several limitations. A larger series of specimens would add meaningful data to this study, and given the small cohort in our study, statistical analysis and conclusions were deemed inappropriate. Additionally, our study only included two female specimens meaning the results may not be generalizable to female patients; however, access to pediatric specimens is severely limited. Access to older specimens and additional female specimens, including those closer to skeletal maturity, would also improve the study and provide more information about the development of these structures in older patients. Having multiple surgeons performing the dissections may increase the variation in anatomic identification of structures. To mitigate this bias, each dissection was reviewed by the group of surgeons to confirm dissected structures and placement of markers at specific landmarks.
In contrast to a previous study of very young (age 3 months to 10 years) pediatric knee specimens, which identified the anterolateral ligament in only one of eight , this series demonstrated the presence of an anterolateral ligament in nine of 14 specimens. This series was an older group of specimens, suggesting that the ligament may become more distinct as it develops over time. Although some recent studies have found the anterolateral ligament in less than 50% of specimens [17, 20, 21], adult cadaveric studies have generally shown it to be present in a much higher percentage of specimens; Dodds et al.  identified the anterolateral ligament in 33 of 40 specimens (83%), Claes et al.  in 40 of 41 specimens (98%), Vincent et al.  in 40 of 40 specimens (100%), and Daggett et al.  in 52 of 52 specimens (100%). Most studies agree that the tibial insertion of the anterolateral ligament can consistently be found approximately halfway between the Gerdy tubercle and the anterior margin of the fibular head [1, 2, 6, 9, 10, 18, 31]. However, there have been conflicting reports on the anatomy of its femoral origin [2, 6, 18, 20] and debate on its relative importance in knee stability and kinematics [11, 15, 17, 21]. Although rarely reported and difficult to quantify, the structure of the anterolateral ligament also seems to vary  with some studies and dissection photographs showing a thin “sheet-like” structure [3, 6, 16] and others appearing as more of a thick band [2, 5, 20]. When ordered according to ossified condylar area, the anterolateral ligament was identified in all seven of the larger specimens, but only two of the seven smaller specimens. Taken together with the understanding that the anterolateral ligament appears to be present in the vast majority of adult specimens , the anterolateral ligament may be a structure that develops throughout the prepubertal period.
The current study demonstrated considerable variation in the location of the anterolateral ligament origin with respect to the lateral collateral ligament origin. With respect to the lateral collateral ligament origin, these specimens showed that the anterolateral ligament originated in several different patterns including (1) distal and anterior to the lateral collateral ligament origin; (2) common anterolateral ligament and lateral collateral ligament origin; (3) proximal and posterior to the lateral collateral ligament origins; (4) anterior to the lateral collateral ligament; and (5) proximal and anterior to its lateral collateral ligament origin. This variation has also been identified in adult cadaveric studies with Claes et al.  identifying the anterolateral ligament origin as anterior to the lateral collateral ligament origin and Dodds et al.  localizing the anterolateral ligament origin as proximal and posterior to the lateral collateral ligament origin. Rezansoff et al.  described two anatomic variants-one anterior-distal to the lateral collateral ligament and one posterior-proximal to the lateral collateral ligament-in a study of 13 knees, whereas Runer et al.  also described two variants-one proximal and posterior to the lateral collateral ligament origin and one sharing the lateral collateral ligament origin. In the current study, the authors found the anterolateral ligament to be an inconsistent structure with regard to its presence, structure, and its femoral origin in prepubescent pediatric knee specimens. Given that multiple femoral origins have been reported in the adult literature, it seems likely that the anatomic relationship of the lateral collateral ligament and anterolateral ligament might vary as was found in our study of pediatric specimens.
The anterolateral ligament origin showed a close relationship to the femoral physis (median 10 mm distal) as did the anterolateral ligament insertion to the tibial physis (median 9 mm proximal). Surgeons considering anterolateral ligament reconstruction in prepubescent patients should be aware of this anatomic relationship. Physicians should be especially careful of causing iatrogenic damage to the distal femoral physis because its undulating structure may confound its relation to the anterolateral ligament origin and ligament reconstructions have the potential to cause growth disturbance [12, 25].
Recently, the anterolateral ligament's status as a true ligament and furthermore its clinical relevance has been called into question [14, 23]; therefore, continued research on the development, structure, and function of the anterolateral ligament in children is needed to further clarify the anatomic role and indications, if any, for combined ACL/anterolateral ligament reconstructions in young athletes. This study expands our understanding of the anterolateral ligament and provides important anatomic information to surgeons considering anterolateral ligament reconstruction concomitantly with primary or revision ACL reconstruction in pediatric athletes.
We thank Allosource (Centennial, CO, USA) for the donation of the cadaveric specimens and nonfinancial research support. We also thank Tom Cycyota and Todd Huft (AlloSource) for their assistance, organization, and support of the dissections.
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