A Patient's Guide to Arthritis of the Thumb
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Introduction
When you stop to think about how much you use your thumbs, it's easy to see why 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 tradeoff 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. |
This guide will help you understand
• how arthritis of the thumb develops
• how it is diagnosed
• what can be done for the condition
Anatomy
 Where is the basal joint, and what does it do?
The basal joint (also known as the carpometacarpal joint or CMC joint) of the thumb is where the metacarpal bone of the thumb attaches to the trapezium bone of the wrist. It is this joint that allows you to move your thumb into your palm--a motion called opposition.
Click for alternative anatomy view of the thumb.
Several ligaments hold the 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.
Click to view cross section of the CMC joint.
Causes
What causes arthritis of the thumb?
Arthritis is a condition in which a joint becomes inflamed--or red, swollen, hot, and painful. Degenerative arthritis is a condition in which a joint wears out, usually slowly over a period of many years. (Doctors sometimes also describe this same condition as degenerative arthrosis. Some doctors believe that degenerative arthritis isn't a true arthritis and that the term can cause confusion. The term arthrosis is used to describe the condition of a worn out joint. The term arthritis is used to describe true inflammatory conditions such as gout, infection, and rheumatoid arthritis.)
Click to view degenerative carpal-metacarpal joint.
Injury to a joint, such as a bad sprain or fracture, can cause damage to the articular cartilage. An injury to the basal joint of the thumb--even if it does not injure the articular cartilage directly--can alter how the joint works. This is true for a fracture of the thumb metacarpal bone where the bone fragments don't quite "line up" correctly and heal differently from the way they were before the break occurred. This is also true when the ligaments around the joint are damaged by a sprain. When an injury results in a change in the way the joint moves, the injury may increase the forces on the articular cartilage surfaces. This is similar to any mechanical device or machinery. If the mechanism is out of balance, it tends to wear out faster.
Click to view cross secton of the CMC joint with arthritic versus normal joint images.
Over 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. Damage has occurred well before the pain begins.
Symptoms
What does arthritis of the thumb feel like?
 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 basal 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. Doctors refer to this sound as crepitus.
Degenerative arthritis will eventually affect the motion of a joint. The basal joint can become stiff and lose motion. It may become difficult to move the thumb away from the palm. This is referred to as a contracture.
Diagnosis
How do doctors identify this problem?
The diagnosis of basal joint arthritis of the thumb begins with your doctor taking a detailed history of the problem. Specifics about any injuries that may have occurred to the hand are important because they may suggest other reasons why the condition exists.
Following the history, the doctor will examine your hand and possibly other joints in your body. The doctor will need to see how the motion of the basal joint has been affected.
Regular X-rays will be taken to see how much the joint is damaged. This test usually determines how bad the degenerative arthritis has become. How much articular cartilage remains in the joint can be estimated with the X-rays.
Click to view X-ray of basal joint.
Click to view X-ray with illustraton of the basal joint.
Treatment Options
What can be done for basal joint arthritis?
The treatment of degenerative arthritis of the basal 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.
Nonsurgical Treatment
Treatment usually begins when the 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.
An injection of cortisone into the joint can give temporary relief. Cortisone is a very powerful anti-inflammatory medication and when injected into the joint itself 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.
Click to view cortisone shot.
Rehabilitation services, such as physical and occupational therapy, have a critical role in the nonoperative treatment plan for basal joint arthritis. A primary goal is to help you learn how to control symptoms and maximize the health of your thumb. You'll learn ways to calm pain and symptoms, which might include the use of rest, heat, or topical rubs. A special brace may help support the thumb and reduce your pain during activity. Range of motion and stretching exercises are 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 therapist will go over tips on how you can get your tasks done with less strain on the joint.
Surgical Treatment
The surgical treatment for arthritis of the basal joint includes several options. At one time, joint replacement with an artificial joint made with silicon was very popular. Problems with silicon implants in other parts of the body have led many surgeons to return to more traditional operations such as fusion and excisional arthroplasty instead. Newer artificial joints are being developed, and in the future we may see more surgeons using these joints.
Basal Joint Fusion
A fusion, or arthrodesis, of any joint is designed to eliminate pain by allowing the bones that make up the joint to grow together, or fuse, into one solid bone. Fusions are used in many joints and were very common before the invention of artificial joints for the replacement of arthritic joints. Even today, joint fusions are still commonly used in many different joints for treating the pain of arthritis.
A fusion of the basal joint of the thumb is done quite often in younger people who need a strong grip, or pinch, more than they need the fine motion of the thumb. People who use their hands for heavy work will probably prefer a fusion over an arthroplasty (described below).
Artificial Joint Replacement
Artificial joints are available for the basal joint. These plastic or metal prostheses are used by some hand surgeons to replace the joint. The prosthesis acts as a spacer to fill the gap created when the arthritic surfaces of the two bones that make up the basal joint are removed.
Click to view silicone implant.
Click to view artificial joint replacement with implant.
Document Link: A Patient's Guide to Artificial Joint Replacement of the Thumb
Excisional Arthroplasty
The traditional operation for treating basal joint arthritis is excisional arthroplasty. This method has been used for many years and has withstood the test of time. The purpose of excisional arthroplasty is to remove the arthritic joint surfaces of the basal joint and replace them with a cushion of material that will keep the bones separated. Most surgeons use a piece of tendon that has been rolled up and placed into the space created by removing the bone surfaces. During the healing phase after surgery, this tendon turns into tough scar tissue that forms a flexible connection between the bones--similar to a joint.
Click to view excisional arthroplasty.
This operation is also combined with a reconstruction of the joint where tendons in the area are used to create a ligament sling between the metacarpal bone of the thumb and the metacarpal bone of the index finger. This helps hold the thumb in place and keeps the space between the bones from collapsing.
Document Link: A Patient's Guide to Excisional Arthroplasty of the Thumb
Rehabilitation
What should I expect following treatment?
If you don't need surgery, range-of-motion exercises for the thumb should be started as pain eases, followed by a program of strengthening. The program advances to include strength exercises for the thumb and fingers. Dexterity and fine motor exercises are used to get your hand and thumb moving smoothly. You'll be given tips on keeping your symptoms controlled. You will probably progress to a home program within four to six weeks.
If you have surgery, your hand will be bandaged with a well-padded dressing and a thumb splint for support. Physical or occupational therapy sessions may be needed after surgery for up to eight weeks. The first few treatments are used to help control the pain and swelling after surgery. Some of the exercises you'll begin to do are to help strengthen and stabilize the muscles around the thumb joint. Other exercises are used to improve fine motor control and dexterity of your hand. You'll be given tips on ways to do your activities while avoiding extra strain on the thumb joint. | 
