An investigation into the anatomical and proteomic properties of the anterolateral ligament (all)

ENGLISH ABSTRACT: The anterolateral ligament (ALL) of the knee has recently been a focus of attention, following suggestions that it plays an important role in internal tibial rotation and is involved in the development of anterolateral rotational instability, particularly after anterior cruciate ligament (ACL) injury (1-19). Despite all the attention, there is still significant uncertainty about the prevalence, exact anatomy, imaging appearance, and molecular identity of the ALL (1-19). These knowledge gaps are further complicated by inconsistent anatomical descriptions, methodological variability between studies, and ongoing debates regarding whether the ALL represents a distinct ligament or a thickening of the joint capsule. The current study aimed to fill these gaps by exploring the ALL through an integrated, multimodal approach comprising of ultrasound imaging, fresh-frozen anatomical body donor dissection, morphometric analysis, and proteomic profiling. Twenty-nine fresh-frozen lower limbs from adult donors were utilised to assess the prevalence and morphometric characteristics of the ALL and the fibular collateral ligament (FCL). Ultrasound scanning was performed prior to dissection to evaluate the accuracy, sensitivity, and specificity of sonographic identification of the ligament. After anatomical isolation, measurements of ligament length, femoral-, and tibial attachment widths, were gathered for both the ALL and FCL. Finally, the proteomic analysis by the Centre for Proteomic and Genomic Research (CPGR) was performed to compare the protein abundance patterns between the two ligaments. This research utilised ultrasound evaluation, anatomical dissection, and exploratory morphometric and proteomic analysis to examine the properties of the anterolateral ligament. While the ultrasound evaluation demonstrated favourable diagnostic properties within the cohort, the limited number of knees positive for the ALL necessitates that these findings be regarded as preliminary. The morphometric and proteomic analysis were descriptive and exploratory. Although the results showed the presence of structural and molecular properties typical of ligaments, they were not intended to offer confirmatory evidence for classification. Ultrasound showed high specificity (96%) and good overall diagnostic performance (accuracy of 91%, sensitivity of 63%) in a subset (n=7, 12.1% of total knees) of limbs. These findings suggest that although the utility of ultrasound for detecting the ALL is limited in donor tissue, it may have potential clinical relevance if combined with higher-resolution imaging or used in the living patient. Anatomical dissection demonstrated an ALL prevalence of 13.8%. Morphometric findings demonstrated no significant side differences in FCL dimensions and no significant differences between the ALL and FCL in terms of ligament length or tibial attachment width. A significant difference in femoral attachment width was demonstrated, with the FCL demonstrating a broader origin, when compared to the ALL. Proteomic profiling yielded the first molecular data on the ALL. The ALL and FCL showed highly similar extracellular matrix (ECM) composition, including type I collagen, type III collagen, decorin, biglycan, fibronectin, and tenascin-C-proteins characteristic of load-bearing ligaments. The FCL showed higher collagen abundance, and the ALL demonstrated high levels of decorin (20-22). In conclusion, this study provides new anatomical, imaging, and biochemical insights into the ALL, representing the first combined investigation of its structural and proteomic characteristics. The findings further support the potential biomechanical role of the ALL in rotational knee stability and provide basic data for future anatomical, biomechanical, and clinical studies.

Grantor dc:publisher

Stellenbosch : Stellenbosch University

Year dc:date.issued

2026

Author dc:creator

• Zehrt, Megan

Advisors dc:contributor.advisor

• Briers, Nanette
• Correia, Janine

Language dc:language.iso

en

Repository record dc:identifier.uri

https://scholar.sun.ac.za/handle/10019.1/135540

OAI identifier oai:identifier

oai:scholar.sun.ac.za:10019.1/135540