A Holstein-Lewis fracture is a spiral fracture involving the distal third of the humerus which causes entrapment of the radial nerve. The radial nerve originates from the posterior cord of the brachial plexus. As the radial nerve travels posterior to the humerus, it provides innervation to the dorsal upper arm muscles. The radial nerve then travels anterior to give innervation to the extensor muscles of the wrist and hand.
Interruption of the radial nerve such as with a Holstein-Lewis fracture will cause the condition known as “wrist drop”. A radial nerve injury occurs in about 18% of cases involving a humerus fracture. Radial nerve injuries are common with distal third fractures of the humerus, especially if the fragment is displaced laterally. As the nerve passes through the intermuscular septum, it becomes trapped or lacerated. Injuries to the nerve include neuropraxia and axonotmesis.
Neuropraxia occurs when there is a minor compression or contusion of the nerve. It is similar to a temporary concussion. Axonotmesis is an injury which causes a breakdown of the axon. The Schwann cell and endoneurium are left intact. With temporary concussion of the nerve, 90% of injuries usually recover within 3-4 months. However, if the fracture is open and associated with a nerve injury, the nerve could be lacerated and exploration should be done.
When treating an open fracture associated with a radial nerve injury, you will debride the wound and an exploration of the nerve and fixation of the fracture should be done. With an anterolateral approach, you will explore the nerve between the brachialis and the brachioradialis. A posterior approach is biomechanically better as the humerus is flat posteriorly, making it easy to apply the plate. However, nerve exploration in the posterior approach may be difficult. With a closed fracture, the fracture is usually treated without surgery—according to the principles of fracture treatment. You will observe the nerve for recovery.
Radial nerve palsy is not a contraindication to functional bracing. Wrist extension is expected to recover before finger extension and the brachioradialis muscle is the first to recover. You will want to obtain an EMG at 3-4 weeks. Positive and sharp P waves are bad and an indication of acute denervation. Polyphasic waves are good. Polyphasic motor unit activity is early evidence of nerve regeneration. The nerve can be explored after 4 months of observation if no recovery occurs with anticipation of nerve repair, nerve graft, or tendon transfer. Sometimes, working on the nerve in addition to a tendon transfer is necessary, especially in younger patients.
Secondary nerve injury from manipulation of the fracture may occur. If the injury occurs during manipulation of the fracture, a surgical option or nonsurgical option is open to debate. With late nerve exploration, the fracture may already be healing. The result of nerve repair is as good as primary exploration and repair.
