PT Tip of the Month Archive

Basal Joint Arthritis

Named after the bones that make up the thumb, the carpometacarpal joint is the union of the base of the thumb to the trapezium carpal bone of the wrist. This joint is the most common site for arthritis in the hand and is frequently referred to as the basal joint. Due to the shape of this joint and the lifetime use of our hands, the basal joint is very prone to osteoarthritis caused by wear and tear and therefore the prevalence of this condition increases with age. Researchers have not linked any environmental or genetic factors to the onset of this disorder, however it is seen most frequently in postmenopausal women, with the female to male ratio being 6:1.

Anatomy and Cause

The base of the thumb’s metacarpal bone and the trapezium carpal bone articulate and function to allow the thumb to swivel and pivot to make a grasp. Like most joints in the body, it is covered with cartilage to protect the joint and let it glide more easily. This complex joint is supported by the volar oblique ligament. As we age the volar oblique ligament will weaken and stretch. Due to this loss of congruency the joint begins to rub and grind, thinning out the cartilage creating arthritis. Bone spurs can then also occur. As the degeneration continues, the basal joint can slip out of place and sublet causing the thumb to collapse into the palm. This posture is known as a “zigzag” or “Z deformity.”

Signs and Symptoms

Initial signs are commonly pain at the base of the thumb radiating to the palm of the hand with activity, particularly requiring excessive gripping or forceful pinching. Many people will begin to report having difficulty opening a jar, turning doorknobs, or writing. As the arthritis continues to progress, weakness and loss of motion set in, causing pain to become more constant and loss of function. Collapsing of the thumb and the zig zag deformity can eventually occur. A grinding sensation may also be present at the joint.


A diagnosis is most commonly made by describing the symptoms of your condition and with a thorough exam by your clinician. Like arthritis of any joint, the appearance of the thumb joint can change with the development of bone spurs and loss of cartilage. X-rays are not required to make a diagnosis, but they can help verify these changes and evaluate the severity of the problem.



The initial treatment of basal thumb arthritis of any stage is rest, anti‐inflammatory drugs, and activity modifications. Patients may be referred to physical therapy or occupational therapy for thumb intrinsic and extrinsic muscle strengthening exercises. Clinicians can also fabricate a long thumb spica splint to immobilize the wrist and basal joint to prevent excessive stress. Many doctors will recommended the splint be used full time for three to four weeks. If there is improvement, the splint can be worn only during the day and the patient can gradually wean from the splint over the course of 1 month, or use it intermittently when performing heavy activity. Cortisone injections may also be considered, but have a diminishing effect with repeated injections and over time can weaken the capsular support of the joint and further compromise the articular cartilage. If there is no improvement of symptoms after 2 months, surgical options are often considered.

If you think you are experiencing signs and symptoms of basal joint arthritis and would like to be scheduled for a physical therapy evaluation, please contact 617-232-PAIN (7246) for our Brookline office and 617-325-PAIN (7246) for our West Roxbury office.


  1. Burton RI. Basal joint arthrosis of the thumb. Orthop Clin North Am 1973;4:331–48.
  2. Pellegrini VD Jr. Osteoarthritis at the base of the thumb. Orthop Clin North Am 1992;23:83–102.
  3. Glickel SZ. Clinical assessment of the thumb trapeziometacarpal joint. Hand Clin 2001;17:185–95.
  4. Mayo Clinic. Thumb arthritis.
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