Microstructural and Mechanical Properties of the Anterolateral Ligament of the Knee

Abstract

Background: The variable anatomy and controversy of the anterolateral ligament (ALL) reflect the complex relationship among the anterolateral knee structures. Purpose/Hypothesis: The purpose was to quantify the microstructural and mechanical properties of the ALL as compared with the anterolateral capsule (ALC) and lateral collateral ligament (LCL). The primary hypotheses were that (1) there is no difference in these properties between the ALL and ALC and (2) the LCL has significantly different properties from the ALL and ALC. Study Design: Descriptive laboratory study. Methods: The LCL, ALL, and ALC were harvested from 25 cadaveric knees. Mechanical testing and microstructural analyses were performed using quantitative polarized light imaging. The average degree of linear polarization (AVG DoLP; mean strength of collagen alignment) and standard deviation of the angle of polarization (STD AoP; degree of variation in collagen angle orientation) were calculated. Results: Linear region moduli were not different between the ALC and ALL (3.75 vs 3.66 MPa, respectively; P > .99). AVG DoLP values were not different between the ALC and ALL in the linear region (0.10 vs 0.10; P > .99). Similarly, STD AoP values were not different between the ALC and ALL (24.2 vs 21.7; P > .99). The LCL had larger modulus, larger AVG DoLP, and smaller STD AoP values than the ALL and ALC. Of 25 knee specimens, 3 were observed to have a distinct ALL, which exhibited larger modulus, larger AVG DoLP, and smaller STD AoP values as compared with nondistinct ALL samples. Conclusion: There were no differences in the mechanical and microstructural properties between the ALL and ALC. The ALC and ALL exhibited comparably weak and disperse collagen alignment. However, when a distinct ALL was present, the properties were suggestive of a ligamentous structure. Clinical Relevance: The properties of the ALL are similar to those of a ligament only when a distinct ALL is present, but otherwise, for the majority of specimens, ALL properties are closer to those of the capsule. Variability in the ligamentous structure of the ALL suggests that it may be more important in some patients than others and reconstruction may be considered in selective patients. Further study is needed to better understand its selective role and optimal indications for reconstruction.

Donor age and sex have limited effects on the mechanical and microstructural properties of human connective tissues

“…All sample acquisition, sample preparation, mechanical and microstructural testing, and data collection were completed in previously published studies. [12][13][14][15][16][17][18] Samples of 11 different tissues were acquired from a total of 91 donors (48 females, 43 males) with an average age of 56 ± 16 years. The examined tissues, harvested from both the arm and leg (Figure 1 ).…”

“…Detailed information on the dissection techniques of each individual tissue type are included in previous publications. [12][13][14][15][16][17][18] Once harvested, all tissues underwent the same sample preparation procedure before testing. Samples were thinned on a freezing stage (Physitemp Instruments) sledge microtome (Leica 1400, Leica) to a thickness of 0.6-1.0 mm to ensure ample light penetration for collection of the QPLI data: degree of linear polarization (DoLP) and angle of polarization (AoP).…”

“…Analysis and results of mechanical and microstructural data of the 11 tissues were published previously. [12][13][14][15][16][17][18]…”

“…The current study evaluated a collection of previously published data that applied a polarized light imaging technique to measure the dynamic microstructural properties of several human soft tissues of interest, while simultaneously quantifying mechanical properties of tissues under load. [12][13][14][15][16][17][18] This new analysis sought to assess the association of age, sex, and tissue type with material properties and test the hypothesis that age and sex will significantly influence the microstructural and biomechanical properties of cadaveric connective tissues.…”

Biomechanics of aging and osteoarthritic human knee ligaments

“…Tensile properties of the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL) and lateral collateral ligament (LCL) have been explored by numerous researchers (Noyes & Grood, 1976; Woo et al, 1991; Race & Amis, 1994; Robinson, Bull & Amis, 2005; Bonner et al, 2015; Smeets et al, 2017; Cho & Kwak, 2020; Patel et al, 2021), providing important information on their structural and mechanical properties. Data for all four ligaments exists across various sources in the literature; however, these are most often harvested and tested in isolation, obtaining just one ligament type from donors.…”