A Common MT Injury, Part 2: Assessment Tests

By Ben Benjamin, PhD
July 12, 2017

A Common MT Injury, Part 2: Assessment Tests

By Ben Benjamin, PhD
July 12, 2017

Editor's Note: Part 1 of Dr. Benjamin's article on thumb injuries appeared in the July issue and is available in our online archives. A third and final article in this series will follow.


Various forms of massage and bodywork are useful for ligament, tendon and muscle injuries in the thumb but not joint injuries. It's just as important to know what you cannot help as what you can help, so that you can refer your client to the appropriate health care professional. This saves both therapists and clients time and frustration. (Note: If you are skilled in Aaron Mattes' "Active Isolated Stretching," you may be able to help mild thumb joint injuries.)

Assessment of the Thumb

The first structures you want to be concerned with in the thumb are the joints, second the tendons and muscles, and finally the ligaments. The muscles may strain, but they usually heal fairly quickly with a little bit of treatment.  When the joints, tendons or ligaments are injured, the pain generally lasts for a long time without the appropriate treatment.

Since there is minimal referred pain in the thumb, the area where it hurts is usually the area that's injured. However, when one of the joints is injured, the area of pain can expand slightly and be experienced by the client — about a half-inch to an inch in each direction. The definitive indication of what's injured is the assessment test results, not the exact location of the pain.

When assessing a client who's suffering from thumb pain, be sure they've seen a physician to rule out a ligament or tendon rupture and any other serious conditions. Sometimes there is what's called an avulsion fracture, in which part of the bone is torn away with the ligament.

An MRI may be required to assess the damage, as X-rays are sometimes not sufficient. You can have a completely ruptured ulnar collateral ligament (UCL) of the thumb, and the X-ray will show absolutely nothing abnormal. Provided there is no rupture, the following tests will help you assess injuries to the joints of the thumb. Remember there are three separate joints in the thumb:

  • The carpometacarpal (or CMC) joint
  • The metacarpophalangeal (or MP) joint
  • The most distal, the interphalangeal (or IP) joint

IP (Interphalangeal) Thumb Joint Tests

Passive Flexion of the IP Joint

To test the most distal, IP joint of the thumb, place your middle finger at the tip of the client's thumb and your thumb on the middle joint of the thumb. Now gently squeeze to move the IP joint into flexion. Stop as soon as any pain or discomfort is felt.

Passive Extension of the IP Joint

Wrap your index finger around the posterior part of the IP joint, and place your thumb pad on the client's thumb pad. Now — stabilizing with your index finger — use your thumb to press the joint into extension.

If one or both of these tests are painful and/or limited in motion, the person has a traumatic arthritis of their IP joint. This means that the joint is inflamed, irritated and slightly swollen. The synovial membrane within the joint has secreted excess fluid to limit the movement and caused pain as a protective measure.

MP (Metacarpophalangeal) Thumb Joint Tests

Passive Flexion of the MP Joint

To test the middle, or MP joint of the thumb, place your index finger on the posterior portion of the CMC joint and your thumb pad on the posterior aspect of the IP joint. Now slowly squeeze those together, forcing the MP joint into flexion. Again, stop if any pain or discomfort is felt.

Passive Extension of the MP Joint

In order to test this joint in extension, place your thumb at the anterior portion of the IP joint and your index finger on the posterior portion of the MP joint, and then move the MP joint into extension. If either of these tests hurts, the person has injured the MP joint.

CMC (Carpometacarpal) Thumb Joint Tests

Passive Flexion of the CMC Joint

To test the most proximal, or CMC joint, place your thumb on the posterior portion of the client's MP thumb joint and your other fingers on the other side of the hand. Now squeeze your fingers together, forcing the CMC joint into flexion.

Passive Extension of the CMC Joint

To test the CMC joint in extension, place your middle or index finger at the snuffbox; that's the space between the two extensor pollicis tendons of the thumb, right on top of the ulnar collateral ligament of the wrist.

Now place your thumb of the same hand at the anterior portion of the client's MP joint, and gently push the CMC joint into extension. Move very slowly and gently, because this joint can be quite painful when injured.

If either or both of these tests are painful, the person has injured the CMC joint. This is the most commonly injured joint of the thumb. The MP joint is a close second. This joint injury is as common in athletes and manual therapists as in the elderly.

Editor's Note: The final article in this series will discuss treatment of thumb joint injuries.


Resource

  • eOrthopod. "Ulnar Collateral Ligament Injuries of the Thumb." Houston Methodist, Medical Media Group, 2016.