Finger joint replacement
Finger joint replacements are most commonly performed at the proximal interphalangeal joint (PIPJ) and metacarpal interphalangeal joint (MCPJ). The PIP joint replacements are usually performed for osteoarthritis, whereas the MCP joint replacements are typically performed for rheumatoid arthritis and osteoarthritis.
The general principles of surgery are similar for both procedures. The arthritic ends of the bone that have had the articular cartilage destroyed are prepared to accept the new joint replacement.
The joint replacement stems are inserted into the bone canal, and the surrounding bone is allowed to grow onto the implant stem to fix it in place or, in the case of a silicone implant, sit quietly next to the bone as a spacer.
There are several commercially available implants. The most commonly performed in rheumatoid arthritis is a small silicone (plastic) hinge, whilst newer generation implants (usually of two components) are performed for osteoarthritis. The silicone hinge is still implanted in large numbers in both osteo/rheumatoid arthritis.
Proximal Interphalangeal Joint
⦁ The PIP joint is a hinge joint with an average arc of motion of 0 to 100 degrees flexion.
⦁ The bony anatomy is crucial to PIP joint stability in all positions; the base of the middle phalanx is wider volarly, thus helping to prevent dorsal dislocation. The PIP joint is more stable in all positions compared to the MCP joint.
⦁ The proper collateral ligaments originate from the centre of rotation of the proximal phalanx head and are inserted onto the middle phalanx’s volar base; they provide stability in all positions. The accessory collateral ligaments insert onto the volar plate and offer more stability in extension. There is no significant cam effect with the PIP joint.
⦁ The volar plate resists hyperextension and is a key supporting structure of the joint.
Who does it affect and why does it occur?
Arthritis usually occurs in people over the age of 40.
Osteoarthritis is simple wear and tear problem. In this situation, the articular cartilage, which is the slippery lining of the joint, is worn away. In Rheumatoid arthritis, the disease process attacks the lining of the joint and destroys the cartilage.
Symptoms
Pain, swelling and a decreased range of movement is the hallmark of finger joint arthritis.
Clinical examination
The patient may have a stiff, swollen joint. In later stages, the joint may angle to one side or the other due to asymmetric wear of the articular cartilage and bone end.
Investigations
X-rays usually confirm the diagnosis. The features of arthritis on an x-ray are loss of joint space. In a normal joint, the articular cartilage cannot be seen and therefore is a space on x-ray. When the cartilage is gradually worn away, this space is reduced until bone rubs on bone and the space is obliterated. Furthermore, in osteoarthritis, new bone forms at the edges of the joint (osteophyte), cysts (holes) appear in the bone, and the ends of the bone harden, showing an increased white appearance (sclerosis)
Non-operative treatment
Corticosteroid injections into the joint, usually under x-ray control, can often provide pain relief.
Operative treatment
PIP joint replacement
An incision is made, usually under local anaesthetic, on the back of the finger. The tendons are displaced to one side. The ends of the bone are removed, and the medullary canal of each bone is prepared to accept the implant stem. Having inserted the implants, the range of movement is assessed, as is the stability and looseness of the joint. The wounds are sutured back into place, and the patient is placed in a splint. Within two to three days, the patient will be seen by a Hand Therapist, and a structured rehabilitation program will take place.