Chapter 39The Antebrachium
Anatomy
The antebrachium lies between the elbow and carpus and is composed principally of the radius and small vestigial portion of the ulna and the flexor and extensor muscles. The tendons of the superficial and deep digital flexor muscles, the accessory ligament of the superficial digital flexor tendon, and the carpal sheath are discussed elsewhere (see Chapters 69, 70, and 75). The medial aspect of the antebrachium is relatively devoid of soft tissue coverage, and this is important when considering fractures of the radius. Major neurovascular structures include the median artery (continuation of the brachial artery in the proximal antebrachium), vein, and nerve; the radial, ulnar, and cutaneous antebrachial nerves; and the accessory cephalic and cephalic veins.
Clinical Diagnosis and Imaging Considerations
Osteochondroma of the Distal Aspect of the Radius
See Chapter 75 for a discussion of osteochondroma of the distal aspect of the radius.
Radial Fractures
For horses with complete, displaced (unstable) fractures of the radius the diagnosis is straightforward. Radiology is needed only to define fracture configuration and to determine if repair is possible. Radiographs are essential in the initial evaluation of any horse with a wound in the antebrachium or over the proximal aspect of the carpus that has a history of acute, moderate-to-severe lameness associated with the injury. Lameness associated with incomplete or hairline fractures of the radius may be transient, but radiographs often reveal obvious or suspicious fracture lines (Figure 39-2, A). Any radiological evidence of bone injury, often a localized cortical fragmentation or compression fracture, warrants high suspicion of an incomplete fracture, and a full series of radiographs should be obtained. Any horse that has persistent lameness after antebrachial trauma in which original radiological findings were negative should be reevaluated within 7 to 10 days, when a fracture may be evident. The horse should be confined to box rest in the interim. Diagnosis in horses with incomplete fractures or stress fractures can sometimes be difficult. Scintigraphic examination is important to differentiate fracture from other problems of the radius, such as enostosis-like lesions.