Subcutaneous approach to the ulnar shaft

Introduction

Indications

• ORIF, treatment of delayed union or nonunion ulnar fractures.
• Osteotomy of the ulna.
• Treatment of chronic osteomyelitis.
• Ulnar lengthening (in Kienbock's disease).
• Ulnar shortening (in cases of distal radial malunion).

Advantage

• Simplest approaches of all forearm, uncovering the entire length of ulna.

Position of patient

• The patient is placed supine on the operating table, with the arm placed across the chest to expose the subcutaneous border of the ulna.
• Apply a tourniquet after exsanguinating the limb.

Landmarks and incision

Landmarks

• Palpate the subcutaneous border of the ulna along its entire length.
• Palpate the styloid process of the ulna.
• Palpate the olecranon.

Incision

• Start the incision longitudinally over the subcutaneous border of the ulna, depending on the amount of bone that needs to be exposed.

Internervous plane

Between the extensor carpi ulnaris (posterior interosseous nerve) and the flexor carpi ulnaris (ulnar nerve).

Superficial dissection

• Make an incision through the fascia onto the subcutaneous border of the ulna.
• The fibers of the extensor carpi ulnaris muscle nearly always have to be divided to reach the ulna.
• In the region of the olecranon, the plane still is an internervous plane because the anconeus is supplied by the radial nerve and the flexor carpi ulnaris is supplied by the ulnar nerve.

Deep dissection

• Incise the periosteum longitudinally on the posterior aspect of the ulna, both radially and medially, to expose the entire posterior length of the ulna.
• In the proximal fifth of the ulna, part of the insertion of the triceps tendon will need to be detached to gain access to the bone.

Dangers

Ulnar nerve

• The nerve is safe as long as the flexor carpi ulnaris is stripped off the ulna subperiosteally.

How to enlarge the approach

Local measures

• The approach cannot be enlarged usefully by local measures.

Extensile measures

• The approach can be extended over the olecranon and up the back of the arm, either to expose the elbow joint through an olecranon osteotomy or to approach the posterior aspect of the distal two thirds of the humerus.
• Distally, the approach cannot be extended usefully.

Figures