Chinese Journal of Tissue Engineering Research ›› 2026, Vol. 30 ›› Issue (24): 6225-6230.doi: 10.12307/2026.174

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Mechanical differences between medial collateral ligament and lateral collateral ligament and influence of elastin degradation

Xu Hongzhang1, Huang Bo1, Zhao Dongliang2, Hu Ying1, Qiao Dan3, Deng Yuping1, 2, 4   

  1. 1Department of Orthopedics and Traumatology, Hospital of Integrated Traditional Chinese and Western Medicine, Southern Medical University, Guangzhou 510315, Guangdong Province, China; 2Shenzhen Bay Laboratory, Shenzhen Graduate School of Peking University, Shenzhen 518132, Guangdong Province, China; 3Department of Pathology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, Zhejiang Province, China; 4National Key Discipline of Human Anatomy, Guangdong Provincial Key Laboratory of Medical Biomechanics, Guangdong Engineering Research Center for Translation of Medical 3D Printing Application, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, Guangdong Province, China
  • Received:2025-06-03 Revised:2025-09-15 Online:2026-08-28 Published:2026-01-29
  • Contact: Xu Hongzhang, Department of Orthopedics and Traumatology, Hospital of Integrated Traditional Chinese and Western Medicine, Southern Medical University, Guangzhou 510315, Guangdong Province, China
  • About author:Xu Hongzhang, MD, Associate chief physician, Department of Orthopedics and Traumatology, Hospital of Integrated Traditional Chinese and Western Medicine, Southern Medical University, Guangzhou 510315, Guangdong Province, China
  • Supported by:
    National Natural Science Foundation of China (Youth Project), Nos. 82305261 (to DYP) and 12202017 (to ZDL); China Postdoctoral Science Foundation Project, No. 2022M711533 (to DYP); Shenzhen Municipal Science and Technology Plan Project, No. JCYJ20210324130401005 (to ZDL); Shenzhen Municipal Medical Research Special Fund Project, No. A2303037 (to ZDL); Shenzhen Bay Laboratory Startup Fund Project, No. QH3003, 21300021 (to ZDL); Shenzhen Municipal Outstanding Science and Technology Innovation Talent Cultivation Project, No. 2023511739 (to ZDL); Shenzhen Bay Laboratory Supercomputing Center Project (to ZDL)

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Abstract: BACKGROUND: As crucial stabilizers of the knee joint, the medial collateral ligament and lateral collateral ligament play essential roles in restricting valgus and varus movements, respectively. However, the mechanical differences between the medial collateral ligament and lateral collateral ligament, the microstructure characteristics, and the effect of elastin degradation on their mechanical properties remain poorly understood.
OBJECTIVE: To compare the mechanical differences between the medial collateral ligament and lateral collateral ligament, quantify the structural characteristics of the collagen fiber alignment, and investigate the impact of elastin degradation on the mechanical properties.
METHODS: The medial collateral ligament and lateral collateral ligament of the left side of adult pigs were obtained, frozen, and then thawed. The mechanical properties of the medial collateral ligament and lateral collateral ligament were tested using quasi-static uniaxial tensile, and the effect of repeated tensile on the mechanical properties was determined. The collagen fiber structure of the medial collateral ligament and lateral collateral ligament was quantified using two-photon microscopy and second-harmonic generation imaging. To evaluate the effect of elastin degradation on the mechanical properties, the medial collateral ligament and lateral collateral ligament under repeated stretching were incubated in an elastase solution for 12 hours before uniaxial stretching.
RESULTS AND CONCLUSION: (1) The medial collateral ligament exhibited a significantly higher high-tensile modulus of elasticity that the lateral collateral ligament (P < 0.05). There was no significant difference in low-tensile modulus of elasticity between the two groups of ligaments (P > 0.05). Repeated stretching significantly reduced the low-tensile modulus of both the medial collateral ligament and lateral collateral ligament. (2) Elastase treatment led to a significant decrease in both the low- and high-tensile elastic modulus of the medial collateral ligament and lateral collateral ligament, with the reduction of the high-tensile modulus in the lateral collateral ligament being more pronounced than the medial collateral ligament. Following elastase treatment, the low- and high-tensile moduli of the medial collateral ligament were significantly lower than those of the lateral collateral ligament (P < 0.05). (3) Two-photon imaging showed that the collagen fibers of the medial collateral ligament maintained a curled structure, and their fiber waviness was significantly higher than that of the lateral collateral ligament. These findings indicate that the medial collateral ligament exhibits greater elastic properties than the lateral collateral ligament, and elastase treatment has a more substantial impact on the mechanical properties of the lateral collateral ligament. This mechanical behavior might be attributed to the more coiled collagen fiber alignment in the medial collateral ligament.

Key words: medial collateral ligament, lateral collateral ligament, biomechanics, elastin, quasi-static tensile, second harmonics 

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