Grind Test | Carpometacarpal (CMC) 1 OA

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Grind Test | Carpometacarpal (CMC) 1 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 grind test yielded a sensitivity of 64% and a specificity of 100%. The grind test both confirms the diagnosis of CMC osteoarthritis and may distinguish those who do not have it. A negative grind test, however, does not always imply negative radiographic evidence of thumb CMC osteoarthritis. With OA it has to be added that it remains a clinical diagnosis and changes seen on radiographic imaging don’t necessarily need to cause any disability or pain, 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 grasps the thumb meta-carpal and rotates it all while applying axial pressure on the trapezium.

The grind test is considered positive if the patient reports any pain, even a slightly painful sensation, or other sensations such as crepitus in the basal joint region of the thumb.