Thumb CMC Grind Test

Purpose

The purpose of the Thumb CMC Grind Test is to assess the integrity of the thumb CMC joint. Reproduction of the patient's pain and crepitus is a positive test for arthrosis and synovitis. Therapists must be aware of the crank test which both evaluates the joint quality and translational laxity, the distraction test where a pain response indicates joint inflammation and volar compression of the first metacarpal base which also indicates joint inflammation[1].

Technique

The grind test is performed by gripping the patient's metacarpal bone of the thumb and moving it in a circle and loading it with gentle axial forces. A patient with thumb joint arthritis generally complains of a sudden sharp pain at the CMC joint which can also be associated with Crepitus[2]. This indicates a positive test[3].

Evidence

Studies on the specificity and sensitivity of the Grind test were performed by Merrit et al using two examiners and Choa et al. The results are shown below;

Sensitivity and Specificity Analysis[3]
Author Sensitivity Specificity
Merritt et al 42% 80%
Meritt et al 53% 93%
Choa et al 30% 96.7%

References

  1. Colditz JC, Koekebakker N. (2010) A New Splint Design for the Thumb CMC Joint [White Paper] published by Nea International bv / Push Braces, Maastricht-Airport, the Netherlands, www.push.eu
  2. https://medisavvy.com/thumb-grind-test/ accessed online October 17th, 2017
  3. 3.0 3.1 Model, Z., Liu, A. Y., Kang, L., Wolfe, S. W., Burket, J. C., & Lee, S. K. (2016). Evaluation of Physical Examination Tests for Thumb Basal Joint Osteoarthritis. Hand (New York, N.Y.), 11(1), 108–112. http://doi.org/10.1177/1558944715616951