Читать книгу Fractures in the Horse - Группа авторов - Страница 146

Fatigue or stress fractures are common in young equine athletes and can occur in compacta (cortical or subchondral) or trabecular bone. Pathogenetically, repetitive stress causes microdamage accumulation in areas of rapidly remodelling/modelling bone where osteoclastic activity outpaces osteoblastic repair, leaving affected bone relatively osteoporotic and thus predisposed to further microdamage, or progression to failure [37]. Cortical stress fractures occur commonly during training in young Thoroughbred racehorses. Initially, they can result in reduced performance, but if unrecognized can progress to complete and sometimes catastrophic fracture. If discovered early, most cortical stress fractures heal completely. Even if a fracture plane cannot be imaged, this is likely to be a form of gap healing as callus production is usually seen. Some that fail to heal in a timely fashion and are in amenable locations can benefit from internal fixation. Stress fractures in subchondral compacta and trabecular bone are also common in young athletes, often leading either to articular fragmentation, articular fracture, subchondral pain or osteoarthritis [14]. Continued repetitive stress in long bone epiphyses or cuboidal bones can cause accumulation of microdamage or an attempted reparative response of bone modelling. In the absence of an outer cortex on which responsive bone can be deposited, thus increasing diameter and strength, the bone can become intensely dense (often termed sclerotic) leading to brittleness and failure/fracture or other osteoarticular damage [14]. In some situations and locations, healing can occur with rest [40].