In short, rheumatoid arthritis is an inflammatory disease which attacks joints in the body. It can affect the alignment and positioning of those joints, even to the extent that they become stuck in a bent position or become dislocated. Bone erosion caused by RA may make the ends of bones rough and irregular. Patients may eventually notice that their fingers begin to shift toward the direction of their elbow.
In previous posts, we have discussed different types of surgery used in patients living with rheumatoid arthritis, including synovectomy, tendon repair, and carpal tunnel release. Today’s discussion centers around joint replacement and implants.
What is Joint Replacement?
One would think that this is a simple question, right? Take the joint out and put a fake or replacement one in. But in researching this subject, I found it rather difficult to find information which went much beyond this simple concept without become extraordinarily technical.
Wonderful information aimed at the consumer exists regarding hip and knee replacements, but for surgery involving in the hands? Not so much. So I have decided not to discuss hip or knee replacements. However, you may enjoy reviewing the following posts and articles which touch on the subject:
- Dr. Mark Borigini - Joint Replacement Surgery: Right for you?
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) - Joint Replacement Surgery and You
- American Academy of Orthopedic Surgeons (AAOS) offers a detailed article discussing Total Hip Replacement surgery
- Interview with Dr. McCarthy - A Step in the Right Direction, Saturday Evening Post
The Joints of the Hand
Take a quick look at your hand. You can see that each finger has three joints. Even the thumb appears to have three joints when you include where the base of the thumb meets the wrist. Finally, you have a wrist which hopefully moves in multiple directions. I know that I’ve had a hard time remembering which joint is named what, so here is a brief rundown:
- Distal Interphalangeal (DIP) is the joint closest to the fingertip.
- Proximal Interphalangeal (PIP) is the second joint from the fingertip.
- Metacarpophalangeal (MCP) is the large knuckle joint, or third joint from the fingertip.
- Thumb basal joint is where the thumb meets the wrist. The thumb has only one Interphalangeal joint and the Metacarpophalangeal joint.
- The outer joint of the wrist (on the side of the pinkie finger) which involves the ulnar head (from the arm) is called the Distal Radioulnar joint.
Common Problems of the Hands and Fingers
According to E-Hand.com, the Electronic Text Book on Hand Surgery, symptoms in the hands/fingers which may prompt a referral to a hand surgeon include:
- Persistent joint pain and swelling despite medication
- Pain when bending or straightening the fingers
- Numbness or tingling in the fingers
- Stiff, bent or locking fingers
- Inability to straighten the fingers
Common Deformities of the Hands and Fingers
- Ulnar drift occurs when the MCP joints of the fingers begin to point sideways (towards the little finger).
- Swan neck deformity occurs when the PIP (middle finger joint) becomes loose and hyperextended while the DIP joint becomes flexed.
- Boutonniere deformity occurs when the PIP joint flexes and the DIP joint hyperextends.
Surgical Options in the Hands and Fingers
Depending upon which joint is involved and what the underlying problem is, surgical options will vary. Here are some generalizations:
For the DIP joint, replacement is not a good option as the bones are too small to hold the implant well. Joint fusion is a better option to relieve pain while minimizing negative affect on hand function by the lack of motion created by fusing the bones in place.
For the PIP and MCP joints, joint replacement using prosthetic implants is commonly performed. Due to frequent sideways pressure, however, the PIP joint in the index finger is not a good candidate for this type of surgery. The excess force from things such as key turning and manipulation of objects can lead to early implant breakage.
PIP and MCP joint implants are commonly made of silicon rubber, have a flexible hinge, and feature stems which are inserted into the shafts of the finger bones. Familiar names you will come across in reading about this type of silicon joint implant are the Swanson implant and the Sutter implant. View a comparable list of MP and PIP joint implants.
The Journal of the Bone & Joint Surgery published a review of joint replacements in the hand. Read Focus On: Anatomical Small Joint Replacement in the Hand (pdf) which includes images and descriptions of surgery. Additional radiographic images of various joints implants can be found here, specifically Figures 11-13 which are of hands.
Rather than using a silicon replacement of the thumb basal joint, the more common procedure involves using the patient’s own tendon to stabilize the thumb and resurface the joint. This procedure is called the ligament reconstruction-tendon interposition (LRTI) or the tendon roll.
Problems with the head of the ulna bone (which forms that bump on the outer topside of the wrist) can prevent motion in the wrist or rough edges due to bone erosion may rupture surrounding tendons. It may be necessary to remove the head of the ulna bone using the Darrach procedure or the ulna head excision. You can view a live video of the Darrach procedure here (warning, this is real).
For more information on joint surgery involving the hands and fingers, read Biomechanics of Joint Replacements: Finger to Shoulder (pdf) which provides an excellent review.
For a discussion of changes in MCP joints caused by RA, read Metacarpophalangeal Arthroplasty in Rheumatoid Arthritis.
Common Materials of Joint Implants
Joint implants can be made a various materials, including silicon, plastic, or titanium. The stems of the implants may be cemented in place or non-cemented. Researchers are discovering ways to improve implant attachment, by coating the material with substances to encourage increased bone growth. Read Better Joint Replacements: Titanium Coating with Protein "Flower Bouquet" Nanoclusters Strengthens Implant Attachment for a review of research conducted at Georgia Tech.
Finally, an overview discussion of rheumatoid arthritis in the hands can be found on emedicine.medscape.com.