Effects of osteochondral fragmentation and intra-articular triamcinolone acetonide treatment on subchondral bone in the equine carpus.

To determine the effects of osteochondral fragmentation and intra-articular corticosteroid treatment on dynamics of bone remodelling and fragility, 12 horses each had a unilateral, 8 mm osteochondral fragment created in the distal aspect of one radiocarpal bone. Six of the horses were treated in the fragmented joint, and the other 6 were treated in the nonfragmented joint with 12 mg of triamcinolone acetonide (TA) 14 and 28 days after surgery. All horses were exercised on a high-speed treadmill starting 15 days, and ending 72 days after surgery. Horses treated with TA in the fragmented joints were significantly less lame than those treated in the nonfragmented joints. Third carpal bones from joints with fragments showed significantly more vascularity, single labelled surface, total labelled surface and mineralising surface in subchondral and subjacent trabecular bone. Trends were also seen towards higher vascular canal volume and osteochondral junction remodelling sites in third carpal bones from fragmented joints. No significant differences were seen in microdamage density or size between fragmented and nonfragmented joints. No significant influence of TA treatment was seen on any parameter measured. The results from this study show that osteochondral fragmentation induces significant changes in remodelling of opposing bones, and that the administration of corticosteroids into joints with fragmentation does not significantly alter bone remodelling or fragility.