11/26/2023 0 Comments Greenstick fracture humerus![]() ![]() ![]() The head of the humerus is on the caudal aspect of the bone. The humeral head articulates proximally with the scapula, and the humeral condyle articulates distally with the radius and ulna. The humerus is an important bone for transfer of weight and for propelling the body forward by its position, it also provides a protective function for the thorax. It is important that differences in anatomy between the canine and feline humerus are understood, as they dictate position, method of application, and size of implants used. The success of a fracture fixation method depends largely on correct implant application and a sound knowledge of both skeletal and soft tissue anatomy. Humeral fractures are inevitably painful, and appropriate pain relief should be provided preoperatively and postoperatively. Effective bandaging of the affected limb for temporary immobilization before surgery or for transport to a referral clinic is possible only with a spica splint. Alternatively, a horizontal beam view of the humerus can be useful for radiography in the conscious or sedated patient. Positioning the dog or cat in dorsal recumbency with the limb pulled caudally and slightly laterally can be useful for taking a craniocaudal view of the humerus to avoid a foreshortened image. Views of the contralateral unfractured humerus are particularly useful when the traumatized bone is severely comminuted. Mediolateral and craniocaudal or caudocranial radiographs should be taken of both humeri before fracture repair is attempted. 30 If cutaneous sensation is present in the affected leg, motor function is usually regained within 1 to 6 weeks in most animals. Nerve conduction studies are helpful only approximately 7 days after the injury occurs. Physical examination tests such as toe pinch and skin prick should be performed the presence of Horner’s syndrome or loss of the panniculus reflex together with neurologic deficits in the forelimb would be indicative of a brachial plexus injury. 69 It is important before surgery to ascertain that the nerve supply to the leg is intact radial nerve injury or a brachial plexus or spinal nerve root avulsion can occur concurrent with humeral fracture. This mimics the appearance of loss of proprioception resulting from nerve injury. Most patients with a humeral fracture carry the leg with the affected elbow dropped and with the paw resting on its dorsal surface because of pain and weakness in the extensor musculature. A large number of animals with humeral fractures have concurrent thoracic, abdominal, or skull injuries. ![]() 49įigure 52-1 The humeral supracondylar foramen in the cat through which the median nerve and brachial artery pass.īecause of the location of the humerus in relation to the vital structures of the head and thorax, a careful evaluation of the patient with a humeral fracture should be performed before further investigation and surgery. Additionally, the medullary canal tapers and effectively ends far proximal to the distal aspect of the bone, limiting intramedullary pin purchase in the condyle of the humerus, and thereby compromising the stability of fracture repair when that method of treatment is used. The distal third of the shaft in the dog and cat is compressed in a craniocaudal direction, and this dense cortical bone with its close association with the radius and ulna is prone to shattering and fissuring. In the cat, the median nerve and a branch of the brachial artery pass through the supracondylar foramen ( Figure 52-1). The radial nerve crosses the distolateral aspect, and the median and ulnar nerves run on the medial aspect. It is an upper limb bone with a large surrounding muscle mass, it is an S-shaped bone with a twist, and ridges proximally and distally make accurate plate contouring difficult. 34 The humerus is a difficult bone to surgically approach and repair because of its shape, location, and surrounding anatomic structures. 5, 90 Most humeral fractures involve the middle and distal one third of the bone. 37, 42, 63, 68 Diaphyseal humeral fractures are caused by road traffic accidents, gunshots, and falls distal fractures are caused mainly by falls or jumps. Humeral fractures account for 8% to 10% of fractures in dogs and 5% to 13% of fractures in cats.
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