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Biomechanical Testing of Murine Tendons
Published on: October 15, 2019
Differences in cellular and microstructural properties of the semitendinosus muscle tendon between young and adult
Kazuki Asai1, Junsuke Nakase1, Tatsuya Ishikawa2
1Department of Orthopaedic Surgery, Graduate School of Medical Science Kanazawa University, 13-1 Takara-machi, 920-8641, Kanazawa, Japan.
Insights
Human semitendinosus tendon cells and collagen structure change significantly with age. These findings are crucial for understanding pediatric anterior cruciate ligament reconstruction outcomes.
Area of Science:
- Orthopedic Surgery
- Biomedical Engineering
- Human Anatomy
Background:
- Pediatric anterior cruciate ligament reconstruction outcomes are often poor.
- Tendon cellular and microstructural properties significantly influence mechanical strength.
- Understanding age-related changes is vital for improving surgical techniques.
Purpose of the Study:
- To investigate the impact of growth on the cellular and microstructural characteristics of the human semitendinosus muscle tendon.
- To correlate age-related cellular and microstructural changes with potential implications for tendon function.
Main Methods:
- Analysis of semitendinosus tendon samples from 76 patients across three age groups: immature, young, and adult.
- Assessment of cell density and nuclei shape using hematoxylin and eosin staining.
- Evaluation of collagen fibril diameter and distribution via electron microscopy.
Main Results:
- Tendon cell nuclei became more elongated with age, and cell density significantly decreased.
- Mean collagen fibril diameter increased, and distribution patterns shifted from right-skewed to flat with age.
- All observed changes in cellular and microstructural properties were statistically significant across age groups.
Conclusions:
- Significant age-related alterations occur in both tendon cell characteristics and collagen microstructure.
- These findings highlight the developmental changes in tendon properties relevant to pediatric orthopedic procedures.
Background:
Poor outcomes associated with anterior cruciate ligament reconstruction in paediatric patients are a major concern. The tendon structure and its cellular characteristics are key factors that affect the mechanical properties of tendons. This study aimed to evaluate the effects of growth on the cellular and microstructural properties of the tendon of the semitendinosus muscle in humans.
Methods:
Semitendinosus muscle tendon samples from 76 patients who underwent ligament reconstruction were examined and divided into three groups: immature (10.8 ± 2.7 years old), young (16.5 ± 1.8 years old), and adult (35.2 ± 8.6 years old), based on age and the state of the epiphyseal plate in the distal femur. The number of tendon cells per unit area was assessed, and the major-to-minor-length ratio of the tendon cell nuclei was calculated to evaluate the shape of the nuclei using haematoxylin and eosin staining. The collagen fibril diameter and distribution were determined using electron microscopy.
Results:
The major-to-minor-length ratio of the tendon cell nuclei significantly increased with age (p-value; immature vs. young: 0.018, young vs adult: 0.001, immature vs adult: 0.001). The shape of the tendon cell nuclei was rounder in the immature group and more elongated in the adult group. A significant decrease in the number of tendon cells was observed with age (immature: 565 ± 134/mm2, young: 356 ± 105/mm2, adult: 272 ± 81/mm2; p-value: immature vs young: 0.001, young vs adult: 0.012, immature vs adult: 0.001). The mean fibril diameter in the immature group was significantly smaller (p-value: immature vs young: 0.018, young vs adult: 0.001, immature vs adult: 0.001). The distribution of the collagen fibrils changed from right skewed in the immature group to flat in the adult group.
Conclusions:
The characteristics of the tendon cells and the microstructure of collagen in muscle tendons significantly changed with age.
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