Introduction

• Polygenic hereditary developmental syndrome.
• Characterized by lesions affecting the medial coronoid process of the ulnar, anconeal process, medial humeral condyle, medial epicondyle.
• Specific lesions: Fragmented medial coronoid process (FMCP) Fragmented medial coronoid process , Ununited anconeal process (UAP) Ununited anconeal process , osteochondrosis (OC) of the humeral condyle Elbow: osteochondritis dissecans , and ununited medial epicondyle (UME).
  Print off the owner factsheet Elbow dysplasia Elbow dysplasia to give to your client.

Pathogenesis

Etiology

• Fragmented medial coronoid process Fragmented medial coronoid process : most common dysplastic elbow lesion. Occurs in 65% of cases of elbow dysplasia. Lesion characterized by fissuring of the cartilage and +/-fragmentation of subchondral bone. Resultant fragments may remain in situ or become displaced. May occur with kissing lesions of the medial humeral condyle. These lesions maybe a consequence of incongruity between the medial coronoid and humeral condyle. Pathogenesis is presumed developmental asynchronicity resulting in a short radius which overloads the medial coronoid process resulting in fragmentation.
  Incongruity has poor observer sensitivity and is rarely visible on the majority of radiographs of dogs with FMCP.
• Osteochondrosis of the humeral condyle Incomplete ossification of the humeral condyle (IOHC) : failure of endochondral ossification and resultant chondromalacia +/- flap formation (Osteochondritis dissecans OCD Elbow: osteochondritis dissecans ). Accounts for 3%-25% of lameness resulting from elbow dysplasia (Dennyet al, 1980; Van Ryssenet al, 1997 ). Variety of severity of lesion from mild fibrillation of cartilage to overt fracture and separation of the osteochondral fragment. Lesion sometimes occurs with FMCP concurrently and it is hypothesized that incongruity of the ulnar trochlear notch and humeral trochlear may result in osteochondral damage.
• Ununited anconeal process Ununited anconeal process : proposed pathogenesis is radio-humeral incongruity where an overlong radius during growth which forces the humeral trochlea proximally into the anconeal process resulting in insult to the ossification center. Recent histopathological does not support earlier suggestions that UAP is a primary osteochondrosis lesion. A diagnosis can only be made in dogs over 20 weeks via a flexed mediolateral radiograph. The condition is bilateral in 20-35% of cases and FMCP is present concurrently in approximately 15% of cases.
• Ununited medial epicondyle origin of several carpal and digital flexor muscles. This epiphysis usually fuses with the medial aspect of the distal humeral condyle by six months of age. Failure of fusion accounts or approximately 3% of cases.

Predisposing factors

General

• Polygenic hereditary syndrome.

Specific

• Nutrition and exercise levels have also been implicated by some studies as predisposing factors.

Diagnosis

Treatment

Prevention

Outcomes