Editorial Commentary: Another Take on the Anterolateral Ligament: High-Grade Are Worse Than Low-Grade Injuries, But the Categorization Is Problematic

The Knee Anterolateral Ligament is Present in 82% of North Americans and 65% of Europeans but Only in 46% of Asian Studies: A Systematic Review of Frequency and Anatomy

PURPOSE

To perform an updated systematic review on the prevalence and morphological characteristics of the anterolateral ligament (ALL) in human cadaveric specimens.

METHODS

Medline, Embase, Scopus, and Google Scholar were searched for studies from 2012 to 2024 describing morphology. Study quality was assessed using the Critical Appraisal Skills Programme checklist and Quality Appraisal for Cadaveric Studies scale. Heterogeneity was analyzed with the I2 statistic, funnel plot, and Q-test. Mean effect size and 95% prediction intervals were calculated. Prevalence and anatomical measurements (length, width, thickness) were analyzed using mean and standard deviations.

RESULTS

Thirty studies were included. The Critical Appraisal Skills Programme identified 3 low-quality studies. Twelve studies met the Quality Appraisal for Cadaveric Studies quality threshold. The prevalence of the ALL was 61.7% (82% in North America, 64.9% in Europe, and 45.8% in Asia). The femoral insertion showed variability near the lateral femoral epicondyle and lateral collateral ligament, while the tibial insertion was midway between Gerdy's tubercle and fibular head. Histological analysis revealed 60% of studies identified ligamentous tissue similar to the anterior cruciate ligament. The mean ALL length was 39.7 mm, width 5.5 mm, and thickness 1.5 mm, with no significant morphological differences among populations.

CONCLUSIONS

This systematic review reveals that the ALL is present in 61.7%, with prevalence rates of 82% in North American studies, 65% in European studies, and 46% in Asian studies. The femoral insertion exhibited substantial variability at/around the lateral femoral epicondyle and lateral collateral ligament, lacking consistency. The tibial insertion was more consistently described as being located about halfway between Gerdy's tubercle and the fibular head. Histological analysis showed that 60% of the included studies identified the ALL as containing ligament-like or ligamentous tissue. The mean length of the ALL was 39.9 mm (range 31-59 mm), the mean width was 5.7 mm (range 2.2-9.0 mm), and the mean thickness was 1.5 mm (range 1.3-2.7 mm). No significant ethnic population differences were observed in morphological measures.

CLINICAL RELEVANCE

The ALL is not consistently present in all patients with knee instability, and the indications for performing an ALL reconstruction or lateral tenodesis remain unclear based solely on morphological factors. As a result, the decision to perform these procedures may need to be made on an individualized basis.

Tibial internal rotation in combined anterior cruciate ligament and high-grade anterolateral ligament injury and its influence on ACL length

Background

Assessment of combined anterolateral ligament (ALL) and anterior cruciate ligament (ACL) injury remains challenging but of high importance as the ALL is a contributing stabilizer of tibial internal rotation. The effect of preoperative static tibial internal rotation on ACL -length remains unknown. The aim of the study was analyze the effect of tibial internal rotation on ACL length in single-bundle ACL reconstructions and to quantify tibial internal rotation in combined ACL and ALL injuries.

Methods

The effect of tibial internal rotation on ACL length was computed in a three-dimensional (3D) model of 10 healthy knees with 5° increments of tibial internal rotation from 0 to 30° resulting in 70 simulations. For each step ACL length was measured. ALL injury severity was graded by a blinded musculoskeletal radiologist in a retrospective analysis of 61 patients who underwent single-bundle ACL reconstruction. Preoperative tibial internal rotation was measured in magnetic resonance imaging (MRI) and its diagnostic performance was analyzed.

Results

ACL length linearly increased 0.7 ± 0.1 mm (2.1 ± 0.5% of initial length) per 5° of tibial internal rotation from 0 to 30° in each patient.

Seventeen patients (27.9%) had an intact ALL (grade 0), 10 (16.4%) a grade 1, 21 (34.4%) a grade 2 and 13 (21.3%) a grade 3 injury of the ALL. Patients with a combined ACL and ALL injury grade 3 had a median static tibial internal rotation of 8.8° (interquartile range (IQR): 8.3) compared to 5.6° (IQR: 6.6) in patients with an ALL injury (grade 0–2) (p = 0.03). A cut-off > 13.3° of tibial internal rotation predicted a high-grade ALL injury with a specificity of 92%, a sensitivity of 30%; area under the curve (AUC) 0.70 (95% CI: 0.54–0.85) (p = 0.03) and an accuracy of 79%.

Conclusion

ACL length linearly increases with tibial internal rotation from 0 to 30°. A combined ACL and high-grade ALL injury was associated with greater preoperative tibial internal rotation. This potentially contributes to unintentional graft laxity in ACL reconstructed patients, in particular with concomitant high-grade ALL tears.

Study design

Cohort study; Level of evidence, 3.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05218-8.

Editorial Commentary: Timing of the Combined Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction: Still a Debatable Issue

Anterior cruciate ligament (ACL) injuries frequently occur as the results of twisting injury of the knee. Accompanying damages to other structures at the time of injury determine the severity of the injury, subsequent surgical procedures, and hence, clinical outcomes. Anterolateral ligament (ALL) seems to act as a side-bar of the ACL rather than a major ligament that should be reconstructed separately. We should also consider the pros and cons of the adding ALL reconstruction procedures. There is insufficient evidence that can either support or refute that ALL plays an important role for knee stability. Determining the timing of the combined reconstruction is still a debatable issue, just like the efficacy of combined ACL and ALL reconstruction.