Minimally invasive approach to the dog humeral shaft

A minimally invasive approach to the humeral shaft is indicated for minimally invasive plate osteosynthesis and intramedullary nail placement.

A medial approach is used.

The key landmarks to be identified are:

• Greater humeral tubercle (proximal landmark)
• Medial epicondyle (distal landmark)

This approach is performed with the patient positioned in dorsal recumbency with the affected limb suspended for draping.

The distal skin incision is centered over the caudal aspect of the medial epicondyle of the humerus.

The caudal and distal aspects of the medial epicondyle are exposed by incising the antebrachial fascia.

The ulnar nerve and the medial head of the triceps muscle are retracted caudally and mobilized.

Note: Care must be taken to protect the ulnar nerve.

For intramedullary pin insertion, the distal edge of the bone is exposed by partially transecting the origin of the superficial digital flexor muscle on the medial epicondylar ridge.

For plate application, an epiperiosteal tunnel directed toward the craniomedial surface of the proximal part of the humerus is created by passing a bunt instrument, such as a periosteal elevator, along the medial side of the humeral shaft.

Proximally the skin is incised over the craniomedial aspect of the humerus. The incision is made in the region of the insertion of the supraspinatus muscle on the greater tubercle.

The subcutaneous fat and fascia are incised along the brachiocephalic muscle, and the muscle is retracted caudally.

The instrument used to create the epiperiosteal tunnel should be palpable under the proximal part of the superficial pectoral muscle. The muscle or fascia is incised over the instrument to complete the tunnel.

Once familiar with this approach, the proximal and distal incisions can be reduced in size.

If necessary, the medial aspect of the humerus can be entirely exposed by extending the minimally invasive approach.

In the distal end, the brachial fascia and subcutaneous fat are closed.

Note: Care must be taken to protect the ulnar nerve.

The superficial pectoral muscle is sutured to the deltoid muscle to close the proximal incision. The external fascia of the brachiocephalic muscle is sutured to the brachial fascia, and the skin and subcutaneous tissue are closed in layers.