Abstract
The coracoid is one of four bones in the avian pectoral girdle. It is a short, thick bone connecting the sternum to the shoulder such that the ventral coracoid articulates with the cranial part of the sternum and the dorsal, distal coracoid articulates with the scapula to define the glenoid cavity. The sterno-coracoid articulation is an elongate synovial joint that permits both hinge-type movements and mediolateral gliding.1 The sternal surface of this articulation is a narrow, curved groove in which the proximal coracoid glides.2 The coracoid, by way of soft tissue attachments, is involved in rotation, depression, elevation, and protraction of the humerus, elbow and forearm flexion, manus and alular extension.5,6,8
Studies have shown that coracoid injuries often yield a characteristic flight pattern described as an inability to gain altitude while flying only short distances, low to the ground. This is most likely due to an inability to raise the injured wing above the shoulder. Wing droop may or may not be present. Concurrent soft tissue trauma often results.4,5
Coracoid fractures are common, and their repair has been described.3,4 However, the diversity of fracture types is poorly defined in the literature and differential prognoses for proximal, mid-shaft, and distal fractures are poorly understood.
Coracoid luxations are less common and are said to have a poor prognosis.7 However, the authors believe coracoid luxations carry a fair to good prognosis depending on variables such as wing loading. Successful rehabilitation of birds with such luxations is reported or is currently in progress (Uman and Pokras, unpublished).3 Coracoid luxations can be difficult to identify radiographically and orthogonal views are important for evaluation. Post-release studies are needed to document the survival of these birds, as well as to determine any long-term osteoarthritic changes that may occur.
Literature Cited
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