Injection Technique for Driver’s Elbow

Indications and Clinical Considerations

The ulnar nerve is susceptible to compression when a driver or passenger rests his or her elbow on the lower sill of the vehicle window while the shoulder is abducted and the elbow flexed. When the elbow is flexed, the proximal edge of the arcuate ligament becomes taut and the total volume of the cubital tunnel is decreased, resulting in increased intratunnel pressure that further compromises the ulnar nerve. Vibration transmitted from the car body to the elbow may also further contribute to compromise of the ulnar nerve.

This entrapment neuropathy manifests as pain and associated paresthesias in the lateral forearm that radiate to the wrist and ring and little fingers. If the condition remains untreated, progressive motor deficit and ultimately flexion contracture of the affected fingers can result. Physical findings include tenderness over the ulnar nerve at the elbow. A positive Tinel sign over the ulnar nerve as it passes beneath the aponeuroses is usually present (see Fig. 58.2 ). Weakness of the intrinsic muscles of the forearm and hand that are innervated by the ulnar nerve may be identified with careful manual muscle testing (see Table 58.1 ). There is always the possibility that a patient with driver’s elbow may also have a coexistent ulnar, median, or radial nerve lesion distal to the elbow that may confuse the clinical picture. Furthermore, cervical radiculopathy and ulnar nerve entrapment may coexist as the so-called “double crush” syndrome, which is seen most often with median nerve entrapment at the wrist or with carpal tunnel syndrome. The clinician should be aware that early in the course of the evolution of driver’s elbow the only physical finding other than tenderness over the nerve may be the loss of sensation on the ulnar side of the little finger.

Driver’s elbow is an entrapment neuropathy caused by external compression of the ulnar nerve, which clinically mimics cubital tunnel syndrome. It is often misdiagnosed as “golfer’s elbow,” and this accounts for the many patients whose golfer’s elbow fails to respond to conservative measures. Driver’s elbow can be distinguished from golfer’s elbow in that in driver’s elbow the maximal tenderness to palpation is over the ulnar nerve 1 inch below the medial epicondyle, whereas in golfer’s elbow the maximal tenderness to palpation is directly over the medial epicondyle as well as a positive golfer’s elbow test ( Fig. 59.1 ). Driver’s elbow should also be differentiated from cervical radiculopathy involving the C7 or C8 roots and golfer’s elbow. Electromyography helps distinguish cervical radiculopathy and driver’s elbow from golfer’s elbow. Ultrasound imaging of the elbow may be useful in assessing the status of the ulnar nerve and can provide important anatomic information when combined with the neurophysiologic data obtained from electromyography ( Fig. 59.2 ). Plain radiographs, ultrasound imaging, and magnetic resonance imaging are indicated in all patients with driver’s elbow to rule out intrinsic disease of the elbow joint ( Fig. 59.3 ). On the basis of the patient’s clinical presentation, additional testing may be indicated, including complete blood count, uric acid, sedimentation rate, and antinuclear antibody testing. The injection technique described later serves as both a diagnostic and a therapeutic maneuver.