Abstract
Synovial joints are quite literally the hinges of the musculoskeletal system, and the articular cartilage plays a crucial role in absorption and dissipation of forces during movement. Focal cartilaginous and osteochondral lesions can be of traumatic or chondropathic degenerative origin. The fibrocartilaginous repair tissue that forms naturally at the site of cartilage damage has inferior biomechanical properties tothe original hyaline cartilage, and so eventually undergoes fibrillation and degeneration, leading to further disruption of joint homeostasis. Both types of lesion will therefore ultimately lead to activity-related pain, joint effusion and decreased mobility, frequently progressing to osteoarthritis. William Hunter’s statement made in 1743 of articular cartilage being a tissue that, “when destroyed, .. is never recovered” is sadly still applicable. This thesis approaches the issue of focal cartilaginous lesion repair from different angles.
The first chapter reviews experimental research on surgical cartilage restoration techniques performed so far in equine models. The high number of equine ongoing studies and the diversity of approaches used, is proof of a still missing long-term solution. Positive results in the reported studies mostly refer to the presence of collagen type 2 or glycosaminoglycans (GAGs) in the (immuno)histochemical analysis of the repair tissue and omit to analyse the crucial biomechanical characteristics of obtained repair cartilage. This aspect ultimately determines the resilience of the repair cartilage and reflects the long-term performance within the biomechanically challenged joint.
Furthermore, also the position within the joint of the damaged area needs to be taken into account, as it has been shown that composition and biomechanical proprieties vary in dependance of their specific location (in line with specific loading conditions). These location-dependent variations have not yet been investigated in the equine stifle. In the second chapter the biochemical composition and architecture of three differently loaded areas of the equine stifle is analyzed. It emerged that glycosaminoglycan content was different between all sites, as were several biomechanical characteristics (equilibrium modulus, dynamic modulus and viscosity). The two weightbearing areas and the non-weightbearing area differed in collagen, parallelism index and angle of collagen fibers. We had hypothesized that site differences also would correlate with the biomechanical characteristics of the cartilage. Indeed, strong correlations were found between several biochemical (proteoglycan content) and biomechanical characteristics (equilibrium modulus, dynamic modulus and phase shift) as well as between architecture (collagen orientation angle) and biomechanical characteristics (equilibrium modulus, dynamic modulus and phase shift).
Original language | English |
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Qualification | Doctor of Philosophy |
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Award date | 15 Jan 2025 |
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Publication status | Published - 15 Jan 2025 |