First Carpometacarpal Joint Osteoarthritis

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Thumb-base osteoarthritis (first CMC joint) is a very common condition that predominantly affects postmenopausal women.


The first CMCJ is highly mobile which is probably linked to an increased rate of degeneration. There is also an association with hypermobility


Increases with age, most common in postmenopausal women. The female to male ratio is 6:1.1


  • Base of thumb pain
  • Activity related particularly gripping, using taps and door knobs, unscrewing lids, turning keys, sewing.
  • Thumb weakness

In advanced stages thenar muscle wasting combined with subluxation and adduction of the 1st metacarpal can lead to a characteristic "squaring" joint deformity"

  • Deformity at the base of the first MCPJ.
  • Adduction of the 1st metacarpal may occur which is visualised by a reduced 1st web space and hyperextension of MCPJ.
  • Palpate for tenderness, crepitation, and subluxation
  • Range of motion
  • Power, pincer strength may be reduced
  • Grind test: Hold the 1st metacarpal, move the thumb in a circular motion, and apply axial compression

Differential Diagnoses

Differential Diagnosis


Xray Inflammatory and rheumatological blood tests if required.


Treatment options are limited, and the available evidence is poor.[1]

Activity Modification

Hand Therapy

Steroid Injection

Corticosteroid injections can be useful to manage pain flares.

Hypertonic Dextrose Injection

Steroid slightly more effective at one month, dextrose slightly more effective at six months.[2]


The main options are arthrodesis and trapeziectomy. See for more information.


  1. โ†‘ Tenti S, Cheleschi S, Mondanelli N, Giannotti S, Fioravanti A. New Trends in Injection-Based Therapy for Thumb-Base Osteoarthritis: Where Are We and where Are We Going? Front Pharmacol. 2021 Apr 13;12:637904. doi: 10.3389/fphar.2021.637904. PMID: 33927620; PMCID: PMC8079141.
  2. โ†‘ Jahangiri A, Moghaddam FR, Najafi S. Hypertonic dextrose versus corticosteroid local injection for the treatment of osteoarthritis in the first carpometacarpal joint: a double-blind randomized clinical trial. J Orthop Sci. 2014 Sep;19(5):737-43. doi: 10.1007/s00776-014-0587-2. Epub 2014 Aug 27. PMID: 25158896.

Literature Review