Arthroplasty of the small Joints of the hand

Abstract

Bones and joints of the hand (starting from the wrist) consist of five carpometacarpal joints (CMC I–V), 5 metacarpophalangeal joints (MCP I–V), proximal and distal interphalangeal joints (PIP and DIP joints). MCP consists of metacarpal head, the proximal phalanx, the volar plate, the two collateral ligaments, the two accessory collateral ligaments, and the sagittal band. It has the outward appearance of a ball-and-socket joint with three degrees of freedom; but it actually acts more as a multiaxial condyloid joint, with its primary motion in flexion and extension. It is also capable of abduction and adduction (radial and ulnar deviation) as well as rotation about its longitudinal axis. The first carpometacarpal joint is a diarthrodial joint, made of reciprocal concave surfaces of the trapezium and the first metacarpal. It has also been described as a saddle joint because of its appearance as two saddles coming together at 90° angles The metacarpophalangeal joint is more intrinsically unstable than the other joints of the finger, and is therefore more vulnerable to the deforming forces associated with rheumatoid arthritis. As the range of motion in rheumatoid arthritis is decreased. Unfortunately, the first carpometacarpal joint is a common site of osteoarthritis. So it the most commonly operated site in the hand for arthritis. The indications for small joint arthroplasty are the same as those for large joints, namely degenerative, post-traumatic or rheumatoid arthritis. The relative contraindications to arthroplasty are young active patients, manual workers, and patients with significant bone loss, gross instability or previous infection. Osteoarthritis of the hand is a common medical diagnosis made in patients seen in a primary care, rheumatologic, and orthopedic practice. Arthritis in the small joints of the hand can be treated with arthrodesis or arthroplasty. Arthrodesis has known risks of infection, pain, and nonunion. Unfortunately, hand function is severely limited by arthrodesis, particularly in certain joints like the metacarpophalangeal (MCP) joint and the proximal interphalangeal (PIP) joints of the ulnar digits. Arthroplasty has been successful in preserving motion and alleviating pain for the distal interphalangeal (DIP), PIP, and MCP joints. Silicone implants have been reliable for many years but still present with the risks of infection, implant breakage, stiffness, and pain. Newer implant designs may limit some of these complications. Different designs of finger joint replacement implants can be divided into three categories hinged implants, flexible one-piece implants and surface replacement implants.