Pressure Shear Test | Carpometacarpal OA

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Pressure Shear Test | Carpometacarpal OA | Thumb Osteoarthritis

Thumb osteoarthritis (OA) is a painful and debilitating condition that affects a large proportion of the adult population, with radiographic prevalence reaching 90% in both men and women by the age of 80. This condition can cause pain at the base of the thumb, progressive loss of thumb motion, weakness, and decreased coordination, which worsens over time.

Qualitative assessment of the history, physical examination, and radiographs are used to diagnose and treat thumb CMC arthritis. The location, duration, onset, frequency, intensity, and quality of the pain are all under consideration.

Sela et al. (2017) conducted a comparative study to determine the best diagnostic tests for CMC OA of the thumb by comparing the results of 4 provocative tests with the Eaton-Littler classification system of radiologic evaluation of the CMC joint.

Eaton-Littler Classification

Subtle carpometacarpal joint space widening
Slight carpometacarpal joint space narrowing, sclerosis, and cystic changes with osteophytes or loose bodies < 2mm
Advanced carpometacarpal joint space narrowing, sclerosis, and cystic changes with osteophytes or loose bodies > 2mm
Arthritic changes in the carpometacarpal joint as in stage III with scaphotrapezial arthritis

In their study, the pressure-shear test yielded a sensitivity of 99% and a specificity of 95%. The pressure-shear test thus appears to have a good ability to both confirm the diagnosis of CMC osteoarthritis and to identify those who do not have it. In the study, the test was performed last in a series of 4 provocative tests, which may have sensitized the joint. Furthermore, this study was the first to formally investigate its diagnostic accuracy in a surgical setting, which is why we give this test a moderate clinical value.

To conduct the test, the patient is in sitting position and the hand is placed on a stable surface such as the examination table. The examiner grasps the patient’s hand with one hand in order to stabilize it. The patient’s wrist and metacarpals are in neutral position. With the other hand, the examiner applies pressure over the anterior oblique ligament and creates a shearing force across the CMC joint by rocking the metacarpal across the trapezium.

The test is considered positive if the patient repots any pain (even a slightly painful sensation) in the basal joint region of the thumb.