Medial approach to the dog humeral shaft

A medial approach to the humeral shaft is mainly used in dogs for plate fixation of midshaft and distal fractures.

Note: Proximal fractures are visualized through a lateral approach.

The following bundle of vascular structures and nerves on the distal medial humerus should be protected during the approach:

• Median nerve
• Ulnar nerve
• Brachial artery
• Brachial vein

Note: The median nerve cannot be moved freely in cats since it runs through the supracondylar foramen.

This approach can be performed with the patient positioned in dorsal recumbency.

It can also be done with the patient positioned in lateral recumbency with the injured leg towards the surgical table and the opposite leg abducted.

The skin is incised proximal from a level distal of the greater tubercle and extended distally to the medial epicondyle. The length of the skin incision depends on the fracture location.

Subcutaneous fat and fascia are incised following the same line and elevated with the skin.

The deep brachial fascia is incised along the caudal border of the brachiocephalic muscle and the distal border of the superficial pectoral muscle.

Distal to the superficial pectoral muscle, the fascia is dissected carefully from the neurovascular structures.

Note: Care must be taken to preserve the underlying neurovascular structures in the distal region of the approach.

The brachiocephalic muscle is retraced cranially to expose the insertion of the superficial pectoral muscle on the shaft of the humerus. The insertion is incised close to the bone from its distal end proximally until the cephalic vein.

If a more proximal exposure of the humerus is needed, the incision along the superficial pectoral muscle is extended proximally by blunt dissection between muscle fibers along a line that runs parallel to the cephalic vein.

For optimal exposure of the proximal humeral shaft, the biceps brachii muscle is retracted caudally, and the proximal brachiocephalic muscle is retracted cranially.

The remaining attached part of the superficial pectoral muscle is retracted as needed for plate application.

If necessary, the cephalic vein can be ligated, and the entire insertion of the pectoral muscle incised.

The biceps brachii muscle is retracted cranially to expose the middle and distal parts of the bone. Careful dissection along the muscle's caudal border is required to separate it from the vessels and nerves.

Note: It is necessary to protect the proximal and distal branches of the musculocutaneous nerves where they penetrate the muscle.

For more proximal exposure, transecting the deep pectoral muscle on the greater tubercle is possible.

The superficial pectoral muscle is sutured to its insertion or the fascia of the brachialis muscle using continuous sutures.

The deep fascial incisions are closed. Following this, the subcutaneous fat and fascia, as well as the skin, are closed.