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

Abstract

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.