Supinator Syndrome

This blog article on “Supinator Syndrome” is an excerpt from the Sports Medicine Acupuncture: An Integrated Approach Combining Sports Medicine with Traditional Chinese Medicine textbook available from smatextbook.com.

The Great Imitator for Lateral Epicondylitis

Figure 1. Increased tension in the supinator muscle can entrap the posterior interosseous nerve.

The deep radial nerve, also known as the posterior interosseous nerve, is a lateral branch extending off of the radial nerve in the region of LI 11 (quchi). The posterior interosseous nerve covers the ulnar side of the forearm along the pathway of the San Jiao channel. The nerve is susceptible to entrapment where it passes through a fibrous narrow channel called the arcade of Frohse (Fig. 1). This entrapment site is located deep to the ulnar side of the LI 10 (shousanli) region, at the proximal edge of the supinator muscle, which lends its name to this injury. The symptoms of supinator syndrome are similar to lateral epicondylitis with the patient complaining of lateral elbow pain. Additionally, both of these injuries are common in racket sports. However, the pain associated with supinator syndrome does not include a fixed pain site located over the common extensor tendon attachment on the lateral epicondyle. The pain of supinator syndrome is reported as worse with activity but diminishing with rest, and it is usually felt as a deep and distending pain in the region of LI 10. The pain can progress to sharp and can spread to the lateral epicondyle with increased activity, which can make a differential diagnosis with lateral epicondylitis even more difficult. Another key difference between supinator syndrome and tennis elbow is that supinator syndrome often presents with weakness of the wrist, finger and thumb extensors. The posterior interosseous nerve innervates the extensor digitorum communis, extensor indicis and extensor carpi radialis brevis, and these muscles will easily fatigue with activity as a result of the nerve entrapment.

Sports Medicine Assessment

• Lateral elbow pain with possible paresthesia into the lateral forearm along the course of the San Jiao channel
• Supinator MMT (Fig. 2) repeated 4-6 times will often create pain in the LI 9 (shanglian), LI 10 (shousanli) and/or LU 5 (chize) region and possibly extend to the lateral epicondyle
• Mill’s and Cozen’s tests for lateral epicondylitis may create a painful response, but the pain is found more in the LI 10 (shousanli) region rather than at the lateral epicondyle
• The patient may report that the forearm and hand feel weak, heavy and/or uncoordinated
• Differential diagnosis: The practitioner will need to differentiate supinator syndrome from other causes of lateral elbow pain, such as: triceps tendinopathy, anconeus strain, lateral epicondylitis and cervical radiculopathy if paresthesia is present

Manual Muscle Test

Figure 2. When nerve entrapment of the posterior interosseous nerve is present, repeated resistive testing of the supinator muscle and increase the symptoms.

1. With the patient in a supine position, the shoulder is flexed to 90˚ with the elbow in full flexion. In this position P 8 (laogong) will be facing LI 16 (jugu)
2. The practitioner’s stabilizing hand supports the elbow while the driving hand covers SI 5 (yanggu)
3. The line of drive is to move the forearm into pronation so that laogong faces upward.

Supinator Motor Entry Point Locations

1. With the forearm pronated, this point is deep to LI 9 (Fig. 3A)
2. With the forearm supinated, this point is approximately 1-1.5 cun distal and 0.5 cun radial to LU 5 (chize) (Fig. 3B). Caution: The radial artery is 0.5-0.75 cun ulnar to this point

Needle Technique: Perpendicular needle insertion 1-1.25 inches deep for both motor points.

Figure 3. A) Supinator motor point in a pronated forearm position. B) Supinator muscle in a supinated forearm position.

These motor points should be combined with other points for a comprehensive acupuncture treatment. The supinator belongs in the myofascial jingjin category of the San Jiao. The practitioner could treat other points to help signal the channel, such as distal motor points including the extensor digitorum communis and/or extensor indicis. Proximal muscle motor points along the San Jiao sinew include the triceps (medial head) and middle deltoid. The pronator teres belongs to the Pericardium sinew channel and is a primary antagonist muscle to the supinator muscle. Treating the pronator teres and the supinator muscle communicates the biao li relationship and stimulates the neural reflex arc between these two muscles. In addition, it is important for the practitioner to remember, that this treatment protocol is only one part of what the patient will present and a thorough TCM differential diagnosis is needed.

After the acupuncture treatment, the following myofascial release technique for the supinator is very effective to use to help reduce tension in the supinator muscle and arcade of Frohse.