You can expose the distal two-thirds of the shaft of a patient's radius by approaching it from its anterolateral side. The difficult part is its proximal third, which is covered by his supinator muscle, through which his posterior interosseous nerve passes. So avoid operating here if you possibly can. Enter his forearm between his brachioradialis laterally (it has a characteristic flat broad tendon) and his flexor carpi radialis medially. His radial artery lies between these two groups of muscles. Pronator teres is inserted into the middle of the radius. You can approach the bone on either side of this muscle, and displace it medially or laterally. Distally, pronator quadratus covers the radius, so you will have to divide it.
OSTEOMYELITIS OF THE RADIUS Follow the general methods for osteomyelitis in Sections 7.4 to 7.6. Apply a tourniquet (3.9, 7.4).
Lay the patient on his back with his arm on a side table, and his forearm supinated. Define the line of the incision by identifying the tendons of his palmaris longus and his flexor carpi radialis at his wrist. Incise just lateral to his flexor carpi radialis. Cut here along the dotted line in B, Fig. 7-8. You will probably only need to incise over the distal third of the bone. If necessary, you can continue the incision proximally to include its middle third.
CAUTION ! Don't extend the incision to the proximal third, or you may injure structures on the front of his elbow.
Cut the deep fascia in the line of the skin incision. Tie any vessels you meet. Retract laterally the three muscles that lie along the lateral border of his forearm[md]brachioradialis, and extensor carpi radialis longus and brevis. When you retract them, his superficial radial nerve will be included with them. This is sensory only.
Find his radial artery and vein, which lie between the lateral group of muscles and flexor carpi radialis. Retract them laterally. You will now have exposed the anterolateral surface of the distal two-thirds of his radius.
Postoperatively, apply plaster only if a fracture threatens or has occurred. If so, apply a tubular forearm cast leaving his wrist and elbow free. The remaining bone will prevent angulation. Encourage him to use his arm.
Fig. 7-8 EXPOSING THE RADIUS AND ULNA. A, a cross-section of the arm at the level of the radial tuberosity. A, B, and E, to expose the patient's radius, enter his forearm between his brachioradialis and his two radial wrist extensors laterally, and his flexor carpi radialis medially. Brachioradialis (E) has a long flat tendon, so you can recognize it easily. The ulna is subcutaneous, so you can approach it easily (C). D, a transverse section through the middle of the arm. E, brachioradialis and flexor carpi radialis, showing the incision for the lower part of the radius passing between them. Note: E, is schematic only, both tendons lie much more laterally in the arm. Partly after Watson Jones, Longman, with kind permission.