Thumb CMC Grind Test is used to assess the osteoarthritis in the carpometacarpal joint of the thumb.
How it’s Performed?
The clinician grasps the thumb metacarpal using the thumb and index finger of one hand and the proximal aspect of the thumb carpometacarpal joint with the other hand.
An axial compressive force, combined with rotation, is applied to the thumb carpometacarpal joint.
What does a positive Thumb Grind Test mean?
Thumb Grind Test is positive if Pain is reported in the carpometacarpal joint of the thumb, it is usually due to osteoarthritis in the joint (differential diagnosis includes a Bennett or Rolando fracture).
Tenderness to palpation and painful instability are additional signs of wear in the joint.
The patient will typically also complain of pain in the carpometacarpal joint of the thumb when opposing the thumb against the resistance of the examiner’s hand.
Sensitivity & Specificity
A study1 found that The grind test has a low sensitivity and a high specificity, that make it as of limited diagnostic value:
Sensitivity: 42 %
Specificity: 80 %
Thumb carpometacarpal joint (also termed basal joint or CMC joint) .
Eaton and Littler staging for CMC joint arthritis:
Normal-appearing joint with the exception of possible widening from synovitis
Joint space narrowing, with debris and osteophytes < 2 mm
Joint space narrowing, with debris and osteophytes 2 mm
Joint space narrowing of scaphotrapezial and trapeziometacarpal articulations
Eaton Radiographic Stages of thumb CMC osteoarthritis
Most commonly performed procedure for advanced thumb CMC osteoarthritis is trapezium excision with ligament reconstruction and tendon interposition.
Zina Model, Andrew Y. Liu, Lana Kang, Scott W. Wolfe, Jayme C. Burket, and Steve K. Lee: Evaluation of Physical Examination Tests for Thumb Basal Joint Osteoarthritis. Hand (N Y). 2016 Mar; 11(1): 108–112. PMID: 27418899
Waggy C: Disorders of the wrist. In: Wadsworth C, ed. Orthopaedic Physical Therapy Home Study Course – The Elbow, Forearm, and Wrist. La Crosse, WI: Orthopaedic Section, APTA, Inc., 1997.
Swanson A: Disabling arthritis at the base of the thumb: Treatment by resection of the trapezium and flexible implant arthroplasty. J Bone Joint Surg Am 54A:456, 1972.
Green DP et al, editors: Green’s operative hand surgery, ed 6, Philadelphia, 2011, Churchill Livingstone, p 409.
Clinical Tests for the Musculoskeletal System 3rd Edition.
Dutton’s Orthopaedic Examination, Evaluation, And Intervention 3rd Edition.