Introduction

• Cause: developmental anomaly - failure of fusion of ossification center of anconeal process - inherited predisposition.
• Seen predominently in German Shepherd Dog.
• Can coexist with other manifestations of elbow dysplasia: fractured cornoid process (FCP) or osteochrondosis dissecans (OCD).
• Signs: progressive, uni- or bilateral forelimb lameness starting between 4-5 months of age, abnormal gait and limb carriage with elbow abducted, reduced range of joint movement, pain plus or minus crepitus on full elbow flexion/extension.
• Diagnosis: clinical signs, radiography.
• Treatment: surgical removal of anconeal process/internal fixation and osteotomy of ulna.
• Prognosis: fair following surgery - degenerative joint disease (DJD) a common sequel.

Pathogenesis

Etiology

• Developmental anomaly - inherited predisposition.
• Unknown - possible osteochondrosis or asynchronous growth of radius and ulna.

Pathophysiology

• Failure of ossification centre of anconeal process to fuse to ulna diaphysis.

• Normally, anconeal process develops as part of ulna diaphysis - in certain breeds, eg German Shepherd Dog, it develops as separate 4th ossification center - appears at 10-13 weeks, fuses to ulna by 18-20 weeks.
• Ununited anconeal process results from failure of fusion of fourth center of ossification.
• Joint instability leads to DJD.
• Shortening of olecranon, subluxation of joint may result.

Diagnosis

Treatment

Prevention

Outcomes