Degeneration and necrosis of the subchondral bone is common in racehorses and commonly precedes fractures. The condition was initially identified in the proximal articular surface of the third carpal bone and is considered to be a consequence of cyclic trauma. It probably precedes most intra-articular fractures. Recently, the presence of subchondral bone disease in other locations in the carpus has been recognized. Cases on the third carpal bone can be diagnosed radiographically with a skyline view. Other locations are often not seen until arthroscopic examination is done. The treatment is surgical debridement, and the prognosis is relatively good.

Last full review/revision March 2012 by Stephen B. Adams, DVM, MS, DACVS; Andrew L. Crawford, BVetMed, CertES (Orth), MRCVS; James K. Belknap, DVM, PhD, DACVS; Jane C. Boswell, MA, VetMB, CertVA, CertES (Orth), DECVS, MRCVS; Peter Clegg, MA, Vet MB, PhD, CertEO, DECVS, MRCVS; Marcus J. Head, BVetMed, MRCVS; C. Wayne McIlwraith, BVSc, PhD, DSc, FRCVS, DACVS; James Schumacher, DVM, MS, DACVS, MRCVS; John Schumacher, DVM, MS, DACVS, MRCVS; Roger K. W. Smith, MA, VetMB, PhD, DEO, DECVS, MRCVS; Chris Whitton, BVSc, FACVSc, PhD; Jean-Marie Denoix, DVM, PhD, Agregé; Joerg A. Auer, DrMedVet, Dr h c, MS, DACVS, DECVS