Development of a standardized surgical (osteo-)chondral defect model in the equine stifle.

Abstract

Osteoarthritis is an important factor for lameness in horses. This degenerative joint disease is characterized by breakdown of articular cartilage. Therefore a significant amount of research on cartilage repair is currently undertaken (Harmel, 2004). Hyaline cartilage consists of chondrocytes, proteoglycans, collagen and water (Weeren van, 2010). Where proteoglycan can be replaced, collagen can be created, however the body is unable to recreate the arching configuration of collagen that anchors hyaline cartilage to the subchondral bone. This configuration is required for cartilage to perform as unique mechanical properties (Bramlage, 2009). Different osteochondral scaffolds are developed for cartilage defect repair. These different scaffolds aim to repair tissue that is superior to fibro-cartilage, which is formed after the natural cartilage repair process (Bramlage, 2009). These scaffolds for human use are currently being tested in animal models. The equine stifle model seems to most closely approximate the human knee cartilage wise (McIlwraith, 2011). Nevertheless, there is no universal model for (osteo-)chondral defect surgery for cartilage repair in the equine stifle. Therefore, a cadaveric study is performed with the aim to optimize this surgical procedure. Both mini-arthrotomy and arthroscopy can be used for (osteo-)chondral scaffold implantation. In this study the advantages and disadvantages of both techniques have been investigated. Arthroscopy, while using gas as a distention medium is preferred because it is minimally invasive, although this technique is more challenging than mini-arthrotomy. Defects of at least 9 mm in diameter and 9 mm in depth (which is the critical size) are created on both the lateral and medial trochlear ridge and the medial condyle by using a drill bit inserted through a surgical sleeve. Different composite scaffolds can be inserted and secured through this same sleeve. Post-operative management includes antibiotics and NSAID’s and a rehabilitation protocol.