Wrist

the part of the upper extremity between the hand and the forearm, also termed the carpus. The wrist comprises several joints or compartments, including the radiocarpal, midcarpal, common carpometacarpal, first carpometacarpal, inferior radioulnar and pisiform  triquetral compartments. Also, see wrist.

2. Pathology

The wrist is involved in numerous pathologic musculoskeletal conditions.

In rheumatoid arthritis, diffuse involvement of the wrist is an important characteristic; all of the compartments ultimately become involved. Rheumatoid arthritis of the wrist is generally accompanied by abnormalities in the fingers. Synovitis and adjacent tenosynovitis are common; extensor carpi ulnaris tenosynovitis often leads to a painless swelling on the ulnar aspect of the wrist. Dorsal subluxation of the distal portion of the ulna, carpal tunnel syndrome, rupture of one or more extensor tendons and synovial cysts are additional findings. Incongruity in cartilaginous and osseous surfaces, laxity of the articular capsule and the ligaments, and muscular and tendinous imbalance can cause malalignment of a wrist in rheumatoid arthritis. Both palmar flexion instability (volar intercalary segmental carpal instability VICI ) and dorsiflexion instability (dorsal intercalary segmental carpal instability DISI ) occur. The caput ulnae syndrome may also be evident. Similar findings may be seen in the seronegative spondyloarthropathy.

In calcium pyrophosphate dihydrate crystal deposition disease, calcification occurs in many tissues of the wrist (triangular fibrocartilage, synovium and ligamentous structures). In addition, carpal malalignment with separation of scaphoid and lunate bones may occur. Unusual predilection for the radiocarpal compartment is evident.

In other crystal-induced diseases, including calcium hydroxyapatite crystal deposition disease, calcific tendinitis is characterized by calcific deposits in or near the tendons of the flexor carpi ulnaris, flexor carpi radialis, common flexor and extensor carpi ulnaris tendons.

Widespread abnormalities of the wrist are typical in patients with haemochromatosis. Alterations include joint space narrowing, sclerosis and cyst formation.

Osteoarthritis involving the wrist is well known to have a radial distribution; changes are usually confined to the trapeziometacarpal (first carpometacarpal) joint and trapezioscaphoid space of the midcarpal joint. Osteoarthritis localized to other compartments of the wrist is unusual in the absence of a history of trauma. However, fracture, subluxation, dislocation or osteonecrosis about the wrist can lead to altered joint motion and result in secondary osteoarthritis. Typical examples include degenerative disease of the radiocarpal and midcarpal compartments after scaphoid injuries, degenerative joint disease of the radiocarpal compartment after osteonecrosis of the lunate bone (Kienbocks disease), and degenerative joint disease of the inferior radioulnar compartment after subluxation of the distal portion of the ulna.

Arthrosis of the lunate  capitate space wit (reverse Colles') fracture

Ulnar styloid process fracture

In addition, internal derangements lead to various abnormalities, such as lesions of the triangular fibrocartilage, ulnar impaction syndrome, carpal instability, carpal tunnel syndrome, ganglion cysts, and adhesive capsulitis.

DR

DR