Massage therapy · Kitchener–WaterlooPosterior Interosseous Nerve Entrapment

The posterior interosseous nerve is a branch of the radial nerve. It can become compressed at the point where it passes through the supinator muscle located in the upper (proximal) forearm, just below the elbow (Węgiel et al., 2023). The nerve supplies the muscles that straighten (extend) the fingers and thumb, as well as helping with wrist extension to a certain degree (Węgiel et al., 2023).

Doctors describe two different problems linked to pressure on this nerve, and they are best thought of as separate conditions (Węgiel et al., 2023):

• Posterior interosseous nerve syndrome: weakness when straightening the fingers and thumb (sometimes called "finger drop"). Numbness shouldn't be present, because this nerve mainly controls muscles rather than feeling (Węgiel et al., 2023).
• Radial tunnel syndrome: pain and tenderness in the upper forearm, over the supinator muscle, often when performing an activity, but without muscle weakness (Węgiel et al., 2023; Engin et al., 2023; Patterson et al., 2024).

The forearm is the part of the arm between the wrist and the elbow. Two long bones make up the forearm, the ulna and the radius, which form the radioulnar joints. The interosseous membrane is what connects these two bones together.

Treatment usually starts with non-surgical care (Węgiel et al., 2023; Engin et al., 2023; Patterson et al., 2024). I can help with hands-on work to ease tight forearm muscles, gentle nerve glides and exercises to keep your arm strong and flexible; if you have weakness, I'll ask you to have it checked by a doctor first. See the My Approach tab for how I work.

Pressure on this nerve near the elbow can show up in two ways, and they need different paths.

If you have forearm pain without weakness (radial tunnel syndrome): I can treat this directly, easing the pressure on the nerve where it passes through the upper forearm muscles and changing the movements that keep irritating it.

If your fingers or thumb are weak, or weakness, numbness or other symptoms are getting worse: see your family doctor or nurse practitioner first, so the cause can be checked. After that, I provide supportive care alongside the plan from your doctor or surgeon, and after surgery I need your surgeon's okay before hands-on treatment.

• Gentle stretching and strengthening for the forearm, wrist and hand, kept pain-free
• A simple self-glide and stretches to do at home, little and often
• Looking at how you use your arm, especially long spells with the palm turned down or repeated twisting
• Showing you how to massage your own forearm with a ball
• A gradual return to gripping, lifting and sport