Surgical Exposures of the Forearm

The elbow surgeon needs some familiarity with exposures of the forearm. These approaches require understanding the local anatomy because the forearm contains a number of neurovascular structures at risk during exposure. There are three clinically relevant surgical exposures for the elbow surgeon: exposure of the radius from an anterior approach (the so-called Henry exposure), exposure of the radius from a posterior approach (the so-called Thompson exposure), and exposure of the ulnar shaft. Additional distal exposures described for management of distal radius fractures (such as the volar flexor carpi radialis approach) exceed the scope of this book.

Anterior Exposure of the Radius

This exposure provides access to the shaft of the radius by dissecting between the flexor carpi radialis (median nerve) and the radial artery on the medial side and the brachioradialis (radial nerve) and the sensory branch of the radial nerve laterally. It continues proximally in the interval between the pronator teres (median nerve) and the brachioradialis and supinator (radial nerve). It provides excellent exposure for the distal two-thirds of the radius; exposure of the proximal third of the radius anteriorly becomes deeper and more difficult, but it can be achieved.

Indications

This exposure is used primarily for the management of fractures of the radius, especially those involving the distal and middle thirds, as well as for exposure of the distal biceps and bicipital tuberosity anteriorly. A portion of this exposure may be used for decompression of the sensory branch of the radial nerve (Wartenberg syndrome).

Skin Incision

The forearm is placed in supination. The incision is performed along a straight line connecting the elbow flexion crease lateral to the distal biceps tendon with the wrist flexion crease radial to the tendon of the flexor carpi radialis ( Fig. 12.1 ).

Distal Portion of the Exposure

After dividing the fascia, the interval between the flexor carpi radialis and the radial artery is identified and developed. The flexor carpi radialis is retracted ulnarly, taking care not to drift into its fibers to avoid damage to the median nerve or its palmar branch. The sensory branch of the radial nerve and the brachioradialis are retracted radially ( Fig. 12.2A ). The radial artery may be left radially or ulnarly. The radial artery is left radially when only the distal third of the radius is planned to be exposed; otherwise it is retracted ulnarly. Subperiosteal elevation of the pronator quadratus distally, and the deep flexors more proximally, allows exposure of the distal half of the radius before encountering the oblique tendon of the pronator teres (see Fig. 12.2B ).

FIG 12.2, (A) The brachioradialis (BR) and sensory branch of the radial nerve have been mobilized radially. (B) The flexor carpi radialis (FCR), pronator quadratus, and flexor mass have been elevated subperiosteally to the level of the pronator teres. 1, FCR; 2, BR; 3, extensor carpi radialis longus; 4, r. superficialis n. radialis; 5, FPL; 6, a. radialis; 7, PL; 8, PT; 9, PQ; 10, S; 11, radius.

Proximal Portion of the Exposure

Dissection proximal to the pronator teres requires further radial retraction of the brachioradialis; the branches from the radial artery to the brachioradialis may be ligated to facilitate retraction. For exposure of the proximal third of the radial shaft, the plane between the pronator teres (ulnarly, median nerve) and the supinator (radially, radial nerve) is identified ( Fig. 12.3A ). The tendon of the pronator teres may be left intact, and hardware may be placed on the shaft by tunneling under the muscle belly (see Fig. 12.3B ). Additional exposure may require detachment of the pronator teres tendon ( Fig. 12.4 ). Further proximal exposure requires subperiosteal detachment of the supinator from ulnar to radial, keeping the arm in supination to decrease the chances of injury to the posterior interosseous nerve ( Fig. 12.5 ). Exposure of the distal biceps and tuberosity requires ligating two separate groups of vessels. The superficial leash of Henry needs to be ligated to expose the biceps tendon. The deeper recurrent radial artery and veins need to be ligated when exposing the tuberosity. Dissection continues along the radial aspect of the distal biceps tendon ( Fig. 12.6 ).