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The joint where the thumb attaches to the hand can suffer from wear and tear. This joint is designed to give the thumb its rather large range of motion, but the trade off is that the joint suffers a lot of stress over the years.This can lead to painful osteoarthritis of this joint that may require surgical treatment as the arthritis progresses. 

The CMC joint (an abbreviation for carpometacarpal joint) of the thumb is where the metacarpal bone of the thumb attaches to the trapezium bone of the wrist.  This is the joint that allows you to move your thumb into your palm, a motion called opposition. Several ligaments hold the CMC joint together.  These ligaments can be injured, such as when you sprain your thumb. The joint surfaces are covered with a material called articular cartilage. This material is the slick, spongy covering that allows one side of a joint to slide against the other joint surface easily.  Arthritis is a condition in which a joint becomes inflamed (red, swollen, hot, and painful).  Osteoarthritis is a degenerative arthritis in which a joint wears out, usually slowly over a period of many years.  This imbalance in the joint mechanics can lead to damage on the articular surface. Since articular cartilage cannot heal itself very well, the damage adds up. Eventually, the joint is no longer able to compensate for the increasing damage, and it begins to hurt. 

 

Symptoms

Pain is the main problem with degenerative arthritis of any joint. This pain occurs at first only related to activity. Usually, once the activity gets underway there is not much pain, but after resting for several minutes the pain and stiffness increase. Later, when the condition worsens, pain may be present even at rest.

The most noticeable problem with CMC joint arthritis is that it becomes difficult to grip anything.  It causes a sharp pain at the base of the thumb in the thick part of the heel of the hand.  When the articular cartilage starts to wear off the joint surface, the joint may make a squeaking sound when moved. Surgeons refer to this sound as crepitus. The joint often becomes stiff and begins to lose motion. Moving the thumb away from the palm may become difficult. This is referred to as a contracture.  Osteoarthritis may cause the CMC joint of the thumb to loosen and to bend back too far (hyperextension). If the middle thumb joint (MCP joint) becomes flexed and the furthest thumb joint also becomes hyperextended, the deformity is named a thumb swan neck deformity. A similar finger deformity some times occurs in people with finger arthritis. 

 

Treatment

The treatment of degenerative arthritis of the CMC joint of the thumb can be divided into the nonsurgical means to control the symptoms and the surgical procedures that are available to treat the condition.  Surgery is usually not considered until the symptoms have become impossible to control without it. 

Treatment usually begins when the CMC joint first becomes painful. This may only occur with heavy use and may simply require mild anti-inflammatory medications, such as Aspirin or Ibuprofen. Reducing the activity, or changing from occupations that require heavy repetitive gripping with the hand, may be necessary to help control the symptoms. 

Rehabilitation services, such as physiotherapy, have a critical role in the non-operative treatment plan for CMC joint arthritis. Physiotherapy can help with range-of-motion and stretching exercises prescribed to improve your thumb motion. Strengthening exercises for the arm and hand help steady the hand and protect the thumb joint from shock and stress. Your physiotherapist will go over tips on how you can get your tasks done with less strain on the joint.  

A brace or splint may also be prescribed to support the thumb. These devices are designed to help reduce pain, prevent deformity, or keep a thumb deformity from getting worse.  Patients with CMC joint arthritis usually only wear the splint at night and when the joint is flared up. It should also be worn to protect the thumb during heavy or repeated hand and thumb activities. 

An steroid injection into the joint can give temporary relief. Cortisone is a very powerful anti-inflammatory medication. When injected into the joint itself, it can help relieve the pain. Pain relief is temporary and usually only lasts several weeks to months. There is a small risk of infection with any injection into the joint, and cortisone injections are no exception.

The surgical treatment for arthritis of the CMC joint includes several options such as a trapeziectomy, a dernervation procedure or joint replacement.