Arthrosis of the distal radioulnar joint (DRUJ) may result as a consequence of disease or trauma affecting the wrist and leading to loss of function of the upper limb. Loss of function related to pain and instability at the DRUJ can be as debilitating as arthritis affecting the radiocarpal joint (1,2). The DRUJ is effective in both wrist and forearm functional activities, working between and bridging the hand and wrist unit with the forearm and the elbow joint. The three joints work together to set the hand in position to perform activities of daily living, avocational pursuits, and work requirements. Injury or disease to any of the three joints affects function. Investigators have suggested that there is a forearm joint with functional units consisting of the proximal and distal radioulnar joints (3). The stability and function of the wrist and forearm are thus a function of the anatomy and mechanics of the DRUJ. Previously, it was believed reasonable to resect or fuse one or more of these joints to relieve pain and improve strength (4,5,6). This, however, often results in a loss of function and at the sacrifice of motion and stability, often so critical to function of the hand and upper limb. Past efforts to treat arthritis of the DRUJ involved resection of the distal ulna (4,5,6,7,8), fusion of the distal ulna with a proximal pseudoarthrosis (1,9,10,11,12), or silicone ulna head capping (13,14). Although effective in relieving pain by removing or fusing opposing bone surfaces, these procedures often resulted in instability of the forearm and wrist, impingement of the distal ulna against the radius, loss of power grip, and restricted ranges of motion (6,15,16,17,18).

Anatomic replacement of the distal ulna has been developed as a method to restore function of the wrist and forearm and salvage failed resection of the distal ulna (19,20,21,22). Now, replacement of all or part of the DRUJ is both possible and successful in properly selected and motivated patients. Prosthetic arthroplasty of the distal ulna alone can be performed with a variety of orthopedic implants with materials of ceramic, pyrolytic carbon, and metal (cobalt-chrome and titanium) (20,21,22,23,24,25,34). Most implants involve replacement of the head of the ulna with a proximal stem within the ulna intermedullary canal (hemiarthroplasty) combined with soft tissue repair of support ligaments (26,27). Both unconstrained and constrained total joint arthroplasty have been developed (20,28,33). Replacement of the head of the DRUJ can be performed with the materials listed above as a total or partial replacement with a variety of indications for acute or chronic replacement. Total joint replacement of the DRUJ (constrained or unconstrained implants) is indicated in patients with extended arthritis, which would preclude a hemiarthroplasty (28,29).

The distal radioulnar joint is a spheroidal joint with primarily two degrees of freedom (rotation and translation). Stability is provided by the joint articular surfaces and important support ligaments (dorsal and volar radioulnar ligaments, triangular fibrocartilage complex, interosseous membrane, and the subsheath of the extensor carpi ulnaris tendon). Basic research studies that reviewed resection of the distal ulna have demonstrated the importance of the DRUJ in maintaining the correct axis
of forearm rotation and the transmission of forces from the hand and wrist to the elbow (3,30,31,32). This is a complex process involving an intact DRUJ, bone contact between the distal ulna and sigmoid fossa of the distal radius, support ligaments, the interosseous membrane, and the radiocapitellar and ulnohumeral joints (2,3,30,31).

Loss of ligament support can lead to or cause instability and result long term in arthritis of the DRUJ (16,18). Restoration of the normal ligaments of the DRUJ is essential for effective function, including stability and force transmission. Equally important is restoration of the joint anatomy (ulnar head and sigmoid fossa) in preserving function of the DRUJ. It is in the latter vein that prosthetic replacement is superior to either resection of the joint or fusion (32,33).

Replacement of the distal ulna is indicated in both acute and chronic conditions of disease and injury of the distal radioulnar joint. Chronic or late prosthetic replacement as a salvage procedure is more commonly performed than acute or primary operative procedures. The acute or semiacute indications for prosthetic replacement included the following:

Late or chronic conditions effecting the DRUJ indications for prosthetic replacement include the following:

Indications may vary for standard prosthesis replacement of the distal ulna versus extended collar prosthetic replacement. Total replacement of the DRUJ is indicated for salvaged procedures when there is a combination of arthritis, deformity, and instability of the DRUJ (28,39). For cases of advanced forearm instability, either a constrained prosthesis or extended collar prosthesis along with ligament reconstruction (Adams procedure or Linscheid-Hui procedure) can restore forearm kinematics and support for the ulnar side of the wrist (26,27).