Joint Health and Cartilage Degeneration
Performance horses experience excessive physical demands during training and competition. This affects a variety of tissues and anatomical sites including ligaments, muscle, tendons, nerves, blood vessels, joint capsules, bone, cartilage, and joints. The common and consistent events that lead to compromising the musculoskeletal system are repetitive microtraumas that overwhelm the tissue’s ability to repair.
Neuromusculoskeletal pain and tissue dysfunction will clearly compromise performance and ultimately major tissue breaches will occur if intervention does not occur. Astute, informed and intelligent observation, management and intervention are essential components in preventing major tissue disruption and animal attrition.
What is Cartilage?
Cartilage is firm elastic living tissue that lines the two bone surfaces in a healthy joint. Along with joint fluid, healthy cartilage protects bone and absorbs the shock of repetitive concussion during exercise. Cartilage is unique among body tissue in having no blood or nerve supply so cannot detect pain and must get its nutrition from nearby structures such as bone and joint fluid. The supply of essential nutrients such as oxygen, glucose, amino acids, vitamins, minerals and the removal of waste products is barely adequate for normal turnover let alone appropriate for the rigors of training. Any insult can easily affect the nutritional status of cartilage. Cartilage is made of cells and a type of elastic cement or matrix. The cartilage cells (chondrocytes) produce complex long-chain molecules called glycosaminoglycans (GAGS) which, when combined with water, give the necessary resilience and compressibility needed for shock absorption and bone protection. The most common GAG is chondroitin sulfate (CS). Another is hyaluronic acid that contributes to the viscosity of the joint fluid and provides flexibility, elasticity and tensile strength to the articular cartilage and tendons. When the compression-resisting capacity is reduced or lost as a result of repetitive microtrauma or direct macrotrauma, physical breakdown of cartilage occurs. Cartilage loses water, becomes dry and less elastic and therefore loses its capacity to resist loading. Joint fluid production is reduced and the degenerative process of arthritis progresses to joint dysfunction, pain and then, of course, poor performance. Inflammation of joint structures, cartilage ulceration, surface adhesions, bone chips, bone necrosis and resorption, periarticular vascular occlusions and a reduced viscosity of joint fluid are all common and ultimate sequel. The final attrition of racehorses is all too well known. AS SOON AS AN ABNORMALITY is noticed- a little a swelling some heat, maybe a slight lameness– stop, look, and evaluate. If your horse is not traveling or performing well on a given day, don’t just keep going, hoping things will get better. Take the time to check things out. As a matter, of course, you should examine your horse’s legs every day before and after exercise. Make sure your horse is fit for the activity you are about to undertake because fatigue is often a contributing factor of tendon injury. Horses also need to be warmed up before exercise and properly cooled down following exercise to minimize all types of athletic injury.