Galloping exercise induces regional changes in bone density within the third and radial carpal bones of Thoroughbred horses

Abstract

Summary This study was performed to test the hypothesis that a localised bone hypertrophy could occur within the subchondral cancellous architecture of the third and radial carpal bones. Using 2 levels of controlled and defined exercise, it was observed that a high intensity treadmill exercise protocol resulted in functional adaptation of the carpal bones. The increase in trabecular thickening and density was seen to be localised to those regions underlying common sites of cartilage degradation, the interface of the thickened trabeculae with the normal architecture in the third carpal bone was coincident with a common site of clinical fractures. The bone changes were determined both qualitatively on examination of slab radiographs and quantified by dual energy x‐ray absorptiometry. The findings from this study are relevant to mechanical factors involved in the pathophysiology of joint degeneration. The potential clinical implications of this study are in relation to changes in the type and duration of exercise regimens used in training of equine athletes. The rapid response of bone to mechanical stimulation has implications in the longer term for localised cartilage degradation. Imaging techniques could be developed to monitor these early bone changes in the specific areas identified in this study and thus allow appropriate changes in training intensity to minimise subsequent damage to the articular surface.

Can exercise modulate the maturation of functionally different immature tendons in the horse?

“…An alternative explanation that the exercise level may have been insufficient in amount or nature to provoke adaptation is less likely because thin-slice radiography of carpal bones from these horses showed adaptive changes to be present within individuals of both groups (data not shown). Rapid adaptation of this same bone has been reported previously in treadmill exercise studies, where treadmill exercise induced maximal site-specific increased bone density after only 4.5 mo of exercise (19). Furthermore, the imposition of the defined increased functional demand in these foals did induce a change in muscle using in vivo muscle biopsies (17).…”

Outcome of lag-screw treatment of incomplete fractures of the frontal plane of the radial facet of the third carpal bone in horses

“…This process is called modelling (Pool 1996) and is a normal physiological process in response to exercise. However, as the density of subchondral bone increases it becomes stiffer so its shock-absorbing capacity decreases (Firth et al 1999) and painful bone oedema can develop (Kawcak 2000). Standardbred horses in training, in which the bone of the radial facet of C3 is of greater density than that of other Standardbred horses undergoing similar training, have been shown to be at greater risk of developing lameness that can be localised to the middle carpal joint (Hopper et al 2004).…”

“…In view of the proposed pathogenesis of the injury, this is not surprising. Cyclical loading during early training induces alteration in C3 (Firth et al 1999;Firth and Rogers 2005), which may eventually result in fracture (Schneider et al 1988). Mechanical loading of subchondral bone causes cyclical bone deformation which stimulates osteoblasts lining the spongiosa of the bone to up-regulate and produce new bone.…”

Assessment of cannon bone mineral density by dual X-ray absorptiometry (DXA) in horses?

“…Aber auch bei zahlreichen Tierspezies wie z.B. dem Schwein (Mitchell et al 2000) oder dem Rind (Becker et al 2001 (Firth et al 1999, Carstanjen et al 2003, Donabedian et al 2005, Toth et al 2010 …”