Small Joint Replacement in the Fingers
Among the joints in the upper body, osteoarthritis most frequently affects the fingers. It is diagnosed nearly 80% of men and 90% of women between the ages of 75 and 79. Rheumatoid arthritis most commonly affects the finger joints.
Patients with osteoarthritis often develop lumps or around the knuckles of the fingers and actually consist of bone spurs, or osteophytes, around the joints. These knuckles often become enlarged, swollen, and stiff.
Severe forms of joint deterioration can cause deformity and debilitating pain. When deteriorating joints become non-responsive to other treatment options and the pain begins to hinder a patient’s daily activities, small joint replacement may be indicated. A successful finger joint replacement can eliminate pain and restore strength and function to the finger and hand by replacing the damaged joint with an artificial one.
About Finger Joints
The finger joints work as hinges allowing the fingers to bend and straighten. The two finger joints that are the most successful with replacement are the PIP joint (proximal IP joint) which is the joint closest to the knuckle and the MP joint (metacarpophalangeal joint), which is the knuckle joint. The DIP joint (distal IP joint) is closest to the tip of the finger, does not do as well with replacement, due to the fact that the bones are very small and do not hold the implant very well.
The best treatment option for advanced arthritis at this joint is a fusion. Hand function is only minimally compromised by lack of motion at this joint after a fusion procedure, while pain is relieved. Dr. Cobb performs this fusion minimally invasively through a scope, resulting in less scar tissue and post-operative pain.
PIP Joint Replacement
The PIP joint is extremely important to hand function and flexibility. Joint replacement is commonly performed in this joint, due to the fact that hand function, especially power grasp, can be hindered by a fusion. The small and ring fingers are the best candidates for joint replacement as they are the most important for power grasp. The index finger is not a good candidate for a PIP joint replacement, as it must withstand sideways forces which accompany movements such as key turning and fine manipulation of objects. These forces cause excess stress on the joint implant and can lead to early implant breakage. The best results with PIP joint replacement are in patients with rheumatoid arthritis and in older, lower-activity patients.
The evaluation of patients as potential candidates for joint replacement includes a comprehensive history and physical examination, as well as a series of x-rays to evaluate the extent of disease. Particular attention is given to the expectations that the patient may have for the type of activities that will be able to be done with the hand after surgery. Typically a silicone or pyrocarbon (Dr. Cobb uses the pyrocarbon the majority of the time) implant is selected based in part on the patient’s underlying disease process, and the stability of the tissues surrounding the joint.
The surgery is typically performed under a regional or general anesthesia. An incision is made on the back or side of the finger and once the damaged joint is removed and cleaned out, the implant is inserted. Patients are immobilized in a splint for approximately 3 weeks after surgery, and then a program of gentle therapy begins with an occupational or physical therapist that we work closely with.
MP Joint Replacement
The MP joints are rarely affected by osteoarthritis. The most common need for joint replacement in this joint is due to degeneration from rheumatoid arthritis.
The surgery is performed by making an incision across the back of the finger joints that are to be replaced. The soft tissues are spread apart with a retractor. Special care is taken not to damage the nearby nerve that passes by the joint. The joint is exposed. The ends of the bones that form the finger joint surfaces are taken off, forming flat surfaces. Next, a burr (a small cutting tool) is used to make a canal into the bones that form the finger joint. The doctor then sizes the stem of the prosthesis to ensure a snug fit into the hollow bone marrow space of the bone. The prosthesis is inserted into the ends of both finger bones. When the new joint is in place, the surgeon wraps the joint with a strip of nearby ligament to form a tight sack. This gives the new implant some added protection and stability. The soft tissues are sewn together, and the finger is splinted and bandaged.