Wrist Arthrodesis 

A painful wrist causes disability and decreased function of the upper extremity. The articulation afforded the hand by the wrist is important for mobility, strength, and dexterity. The pain produced by arthropathy of the wrist causes the patient to use a wrist splint to decrease pain. However, loss of mobility due to splinting is only part of the problem. The pull of the finger and wrist flexors and extensors exerts considerable force on the many intercarpal joints. Pain produced by bone-on-bone contact is compounded by the pressure exerted in active motion, and the result is reluctance of the patient to perform active motion. The goal of wrist arthrodesis is to provide the patient with a relatively pain-free wrist by eliminating movement in arthritic joints.

An image depicting wrist arthritis can be seen below.

Both total and limited wrist arthrodesis originated in an attempt to decrease the pain of wrist joint arthritis. The earliest procedures consisted of decortication and combinations of corticocancellous bone grafts keyed into accurately cut slots and keyways. Immobilization of the wrist was required postoperatively to ensure adequate healing. Later, the use of percutaneous pin fixation allowed for decreased reliance on external immobilization. Steinmann pins were also employed as internal splints in an attempt to provide more rigid fixation. The development of internal fixation with plates and screws revolutionized wrist arthrodesis and almost completely eliminated the need for external immobilization.^[1]

Currently, state-of-the-art total wrist arthrodesis employs the use of a specifically designed dynamic compression plate, which allows rigid fixation with larger screws proximally and smaller screws distally to reduce the risk of fracturing the metacarpals. Limited intercarpal arthrodeses still employ combinations of Kirschner wires (K-wires), screws, staples, and structural bone grafting. Specialty plate and screw constructs have been designed for use in both limited and total arthrodesis of the wrist.^[2]

Arthropathy and resulting arthritis of the wrist cause pain and disability due to bone-on-bone contact between the carpal bones and the distal radius (see images below). Pain is produced when articular surfaces lose their cartilaginous covering and bone is allowed to articulate directly in the joint. Afferent nerves in the exposed subchondral bone relay painful stimuli.

The goal of arthrodesis for painful arthritis is to prevent motion by obtaining bony consolidation of worn joint surfaces and thereby remove the pain generated in the joint. In addition, wrist arthrodesis can be beneficial in providing a more functional hand and upper extremity in patients with deforming spastic hemiplegia.

Frequency

No comprehensive epidemiology data for wrist arthropathy are reported in the literature. However, Watson and Ballet reviewed 4000 wrist radiographs for evidence of arthritis (eg, joint space narrowing, osteophyte formation, subchondral reactive bone formation, subchondral cyst formation).^[3] Of these 4000 radiographs, 210 (5.3%) had unequivocal radiographic changes consistent with wrist arthritis. The scapholunate advanced collapse (SLAC) pattern was most prevalent, noted in 120 (57% of pathologic joints) of the 210 radiographs (see images below).

Triscaphoid arthritis (ie, scaphoid, trapezoid, trapezium) was found in 14% of affected wrists. Nonscaphoid-related arthritis was found in only 3% of affected wrists. The radiolunate joint was almost never affected. Note that this population did not include wrist arthritis due to inflammatory arthropathy.

Causative factors for wrist arthropathy include, but are not limited to, trauma, rheumatoid arthritis, crystalline arthropathy, carpal instability, avascular necrosis, destruction due to tumors, septic arthritis, and mechanical overuse. Wrist arthrodesis is also indicated for stabilization of the wrist when combined with tendon transfers, correction of wrist deformities in patients with spastic hemiplegia, and for salvage of unsuccessful wrist arthroplasty.

Joint arthropathy resulting in wrist arthritis is nearly identical to arthropathy in other joints, including the hip and knee. The principal problem is loss of articular cartilage between the carpal bones and/or the metacarpal and distal radius. The major difference is the fact that the wrist is not normally a weightbearing joint.

There are various etiologies, but the common pathway is destruction of articular cartilage, formation of osteophytes, loss of the normal joint interval, and formation of degenerative subchondral cysts. Bone-on-bone contact produces reactive bone formation in the subchondral area and eventually results in eburnation (sclerosis) of the contacting bone surfaces. Pressure and abrasion irritate afferent nerves in the substance of the bone. Inflammation is either a result of the primary etiology (eg, rheumatoid arthritis, gout) or can be a result of synovial irritation. Prostaglandins and cytokines are generated as a result of inflammation, causing pain and decreased mobility of the wrist.

The history is simple and specific. The patient reports pain in one or both wrists. The individual may recall a history of trauma to the affected wrist or have a related diagnosis such as rheumatoid arthritis^[4] or gout. The patient's pain is usually progressive and, at the time of presentation to an orthopedic surgeon, has already been treated conservatively. The pain is usually exacerbated with use and relieved with rest and nonsteroidal anti-inflammatory medicines. The patient may have swelling and stiffness associated with the wrist pain.

Preoperatively, patients should be assessed for the presence of carpal tunnel syndrome, distal radioulnar joint arthritis, or ulnocarpal impaction syndrome, which may become or remain symptomatic after arthrodesis.

On physical examination, painful range of motion of the wrist is present. Soft-tissue swelling or an effusion may be noted around the wrist. Provocative testing of the carpus may reveal instability or laxity of the intercarpal ligaments. The patient usually has decreased range of motion of the wrist due partly to a mechanical block and partly to pain.

Radiographs of the wrist reveal changes consistent with arthropathy and arthritis. Changes include a decrease in the joint interval in the affected joints, evidence of subchondral reactive bone formation, and possibly, osteophytes and subchondral cysts.

Arthrodesis of the wrist joint is indicated in degenerative joint disease and instability associated with restricted and painful range of motion. Further indications are unsuccessful reconstruction, partial arthrodesis, or arthroplasty, with or without total joint replacement. Total wrist fusion still represents the main treatment for severe posttraumatic disorders of the wrist due to long-standing scaphoid nonunion advanced collapse (SNAC), SLAC (see image below), and occasionally posttraumatic arthritis secondary to distal radius fractures.

Specific indications for radiocarpal arthrodesis

• Posttraumatic osteoarthrosis of the radiocarpal joint and midcarpal joints as commonly observed following chronic scapholunate dissociation complex fractures
• A previous, unsuccessful, more limited arthrodesis
• An unsuccessful total-joint or previous arthroplasty of the radiocarpal joint
• Paralysis of the wrist or hand with potential for reconstruction involving the use of wrist or finger motions for tendon transfer
• Reconstruction following segmental tumor resection, infection, or traumatic segmental bone loss of the distal radius and carpus
• Adolescent spastic hemiplegia with wrist flexion deformity
• Rheumatoid arthritis^[5]

Midcarpal fusion has become increasingly more popular because it preserves motion. However, whether the preserved motion is of real benefit from the patient's point of view is questionable, because complete pain relief is rare following this type of limited wrist fusion. Midcarpal fusion is preferable to total wrist fusion for treatment of progressive carpal collapse (eg, SLAC, SNAC).^{[6, 7]} Currently, patients with either occupations or interests that require intricate use of their hands are believed to have better outcomes with limited arthrodeses because of the preservation of motion.^[8]

Subtotal arthrodesis is not recommended for patients with rheumatoid wrist joints or those engaged in hard manual labor, because the functional results are only negligibly better than those obtained with total arthrodesis. Limited wrist arthrodesis is the surgical fusion of selected bones of the wrist. In each case, the extent of the fusion is determined by the extent of the disease process. Limited wrist arthrodesis is an alternative to complete wrist fusion when a localized area of degenerative change or instability in the carpus is present. It relieves pain, yet it still allows some range of motion.^[9] Biomechanical alterations do occur following limited intracarpal fusions. Subtotal arthrodeses of the wrist are indicated for painful arthritis involving 1 or 2 radiocarpal or intracarpal joint surfaces, stabilization of carpal collapse deformities, failed ligament reconstructions or repairs, or bone tumors with partial carpal involvement.^[10]

Limited wrist arthrodesis is a useful method for treating specific carpal disorders that maximizes residual wrist motion and strength while attempting to eliminate pain. Selective fusion of specific carpal bones can be used in persons with degenerative arthritis, rotatory subluxation of the scaphoid, midcarpal instability, scaphoid nonunion, Kienböck disease, and congenital synchondrosis or partial fusion of specific carpal joints.^[11]

The need for fusion of the capitate, lunate, triquetrum, and hamate is still unclear. Evidence suggests that there may be an improved ability to reduce the capitate on the lunate and a lower rate of nonunion when the triquetrum and scaphoid are excised and the only fusion surfaces are localized between the capitate and lunate. Migration of the screws can be an issue with this technique.^[12]

Traditionally, the approach to the wrist for arthrodesis is dorsally between the third and fourth dorsal compartments (see images below). The third dorsal compartment houses the extensor pollicis longus tendon, and the fourth dorsal compartment houses the extensor digitorum communis and extensor indicis proprius tendons.

A straight, longitudinal incision is centered over the distal radioulnar joint extending distally over the third metacarpal. Care should be taken to avoid transecting the cutaneous sensory branches of the superficial radial nerve, which are directly radial to the incision. The dorsal wrist capsule and extensor retinaculum are opened sharply between the third and fourth dorsal compartments and are sharply elevated with care not to injure the underlying tendons. The extensor pollicis longus tendon is elevated radially over the Lister tubercle, and the tubercle is removed. The tendon of the third compartment is retracted radially, and the tendons of the fourth compartment are retracted ulnarly. Cancellous bone graft can be obtained from the distal radius just radial to the Lister tubercle.

The dorsal intercarpal ligaments are opened sharply, and the articular surfaces that are to be fused are decorticated. Bone graft is placed between the decorticated bone ends. The dorsal prominence of the distal radius, lunate, capitate, and proximal third metacarpal most likely require resection to allow the compression plate to lie flat against the carpal bones (see first image below). Failure to perform this step may result in distraction of the carpal bones when the plate is applied. A lag screw through the radioscaphoid joint can be helpful in preventing ulnar deviation and ulnar impaction syndrome. The dorsal capsule and extensor retinaculum are closed, and then the overlying skin is closed (see second image below).

In total wrist arthrodesis, the joints that are critical to fuse are the radioscaphoid, radiolunate, scaphocapitate, capitate-lunate, capito-trapezoid, and third carpometacarpal joints. The compression plate is sized and applied to provide at least 6 cortices of fixation at the third metacarpal and distal radius. Fusion of the ulnar-sided joints (ie, lunotriquetral, capitate-hamate, triquetrum-hamate) is advised only if significant arthrosis of these joints is present at the time of surgery.

Subtotal wrist arthrodesis operations are exposed in a similar fashion, with the exception that the incision is not extended distally over the third metacarpal. The joints to be fused are similarly decorticated and grafted. The joints can be stabilized with the use of lag screws, plates, K-wires, Steinmann pins, interosseous wires, or a combination of these.

A contraindication to wrist arthrodesis is an open distal radial physis. Severe trauma to the wrist and physis might require epiphysiodesis and, therefore, allow for fusion. A relative contraindication is an elderly patient with a sedentary lifestyle, especially if the targeted wrist is the nondominant wrist. In this situation, an arthroplasty may be more suitable. Other contraindications include (1) quadriparetics who use their motors for modified grasp and transfer techniques, (2) neurologic diseases or injury causing major sensory deprivation in the hand, and (3) advanced rheumatoid disease where stabilization techniques are more suitable than formal arthrodesis.