Fragmentation of the apex of the patella usually occurs secondary to medial patellar desmotomy for the management of upward fixation of the patella. Lesions are believed to occur due to patellar instability as a result of the surgery. The severity of lameness varies from mild stiffness to moderate lameness. A proximal limb flexion test usually exacerbates lameness and femoropatellar joint effusion is usually present. Lameness is localized by diagnostic anesthesia of the femoropatellar joint, and diagnosis is confirmed by radiography. Arthroscopic debridement of the apex of the patella and removal of the osteochondral fragments is the treatment of choice. Prognosis is reasonable but depends on the severity of the condition.

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