6.2 Degenerative arthritis of the wrist

A strong, stable, mobile and painless wrist is the key to function of the hand. The multiple joint compartments of the wrist show very different susceptibility to degenerative arthritis. The frequency of involvement of joints of the wrist determined from study of 210 radiographs was radioscaphoid (RS) joint 55%, scaphoid-trapezoid-trapezium (STT) joint 26%, both RS and STT joints 14%, and other joints 5%. The fact that either the proximal or distal surface of the scaphoid was affected in 95% of cases emphasizes that bone’s importance in the function of the wrist.

Primary osteoarthritis of the radiocarpal joint is uncommon but may be associated with calcium pyrophosphate crystal deposition disease (CPDD) and with haemochromatosis. Most cases are secondary to conditions that damage articular cartilage or to injuries that increase surface pressure on articular cartilage by altering loading and joint contact areas. The causes of secondary degenerative arthritis are listed in Box 6.2.2.

Degenerative arthritis of the radioscaphoid joint is the final common pathway for several disorders that alter the mechanics of the wrist. The path of motion of the scaphoid in the elliptical radioscaphoid joint is controlled by ligamentous attachments to the radius and to the lunate. The scaphoid flexes during radial deviation and extends during ulnar deviation. The radiocarpal load is shared 60:40 between scaphoid and lunate. Injuries that destabilize the scaphoid, either by ligament disruption or by scaphoid fracture, affect the radioscaphoid joint in three ways: excessive scaphoid flexion; decreased articular surface contact; and increased radioscaphoid loading. The articular cartilage that is in contact with the unstable scaphoid (or, in the case of a scaphoid fracture, the unstable distal fragment) deteriorates rapidly in the face of this mechanical challenge, while the spherical and relatively unloaded radiolunate joint is preserved. Later, the capitolunate joint is affected. This characteristic pattern of degeneration is referred to as the ScaphoLunate Advanced Collapse (SLAC) wrist (Figure 6.2.1).

In the early stages, activity-related pain is experienced intermittently on the dorsoradial aspect of the wrist. As the process extends to the midcarpal joint, pain generally increases and is associated with loss of wrist motion and with loss of strength. In some cases, however, pain correlates poorly with the radiographic appearance and function remains good.

The first sign of radioscaphoid osteoarthritis is beaking of the radial styloid. Loss of height of articular cartilage in the radioscaphoid joint and subchondral sclerosis follow. The changes are most marked along the dorsal rim of the radioscaphoid joint and may be associated with osteophytes that are best seen on oblique radiographs (Figure 6.2.2). Chondrocalcinosis may be seen in cases resulting from CPDD (Figure 6.2.3).

Modification of activity, splintage, and analgesic medication are appropriate for modest symptoms. Steroid injection can give useful medium-term relief in patients who prefer to avoid operative treatment. Modest loss of wrist motion is consistent with good function. About 70% of normal daily activities can be accomplished within the range of 40° extension, 40° flexion, and 40-degree radial/ulnar deviation. Many patients adjust to their disability and do not require operative management.

Wrist pain that persists despite non-operative management may require operative treatment (Box 6.2.3). The options are as follows:

Excision of the proximal row of the carpus requires intact articular cartilage on the head of the capitate and the lunate fossa of the radius (Figure 6.2.4). The wrist is immobilized for 3–6 weeks. Strength and mobility improve over at least 12 months. A review of 22 cases after a minimum of 10 years found 14 patients very satisfied, four satisfied, and four failures requiring arthrodesis.

The preservation of the spherical radiolunate joint in the late stages of the SLAC wrist allows it to be used as the sole articulating surface. Radioscaphoid impingement is relieved by excision of the scaphoid and the midcarpal joint is stabilized by arthrodesis (capitolunate or capitate-lunate-hamate-triquetrum) (Figure 6.2.5). Several studies have shown that proximal row carpectomy fares at least as well as scaphoid excision/midcarpal arthrodesis with regard to range of motion (ROM) and strength, and does not have the disadvantages of fixation-related complications, prolonged immobilization, and risk of non-union. However, scaphoid excision and midcarpal arthrodesis is the only alternative to total wrist arthrodesis when damage to the head of the capitate precludes proximal row carpectomy.

Arthrodesis of the radiocarpal joint is indicated for osteoarthritis confined to the radioscaphoid and/or radiolunate joints Intra-articular fracture of the distal radius is the most common cause.

Wrist arthrodesis is the definitive and durable solution for osteoarthritis of the wrist. The joint is fused in 15–25 degrees of extension and 0–15 degrees of ulnar deviation. Plate fixation has significantly a higher fusion rate than other techniques and is the method of choice for degenerative and post-traumatic arthritis (Figure 6.2.5). The arthrodesis must include the radioscaphoid and midcarpal joints, but inclusion of the third carpometacarpal joint is controversial. In most cases, sufficient cancellous bone graft can be obtained from the distal radial metaphysis, obviating the need for iliac crest graft.

Wrist arthroplasty is indicated mainly for severe rheumatoid arthritis. Patients who wish to maintain dexterity for low-demand activities of daily living may be suitable for wrist arthroplasty, but they must be willing to accept permanent restrictions in activity. Many patients with degenerative arthritis are young and active, and not suitable for wrist arthroplasty.

Division of multiple nerve branches that supply the wrist joint has been used to reduce pain from osteoarthritis and other painful disorders, either on its own or combined with other procedures. So-called total denervation requires multiple incisions around the wrist. Partial denervation, usually comprising the terminal branches of the posterior and anterior interosseous nerves through a dorsal approach, is also used. Preoperative diagnostic nerve blocks are believed to be helpful in predicting the effect of denervation.

Osteoarthritis of the scaphoid-trapezoid-trapezium (STT joint) may be idiopathic, associated with CPDD, associated with trapeziometacarpal osteoarthritis, or secondary to trauma (intra-articular fractures and, possibly, ligament injury).

Pain on the dorsoradial aspect of the wrist is the characteristic symptom but the severity of pain is variable and asymptomatic. STT osteoarthritis is frequently seen on radiographs taken for another purpose. Local tenderness may be present over the dorsal and/or palmar surfaces of the STT joint. Loss of wrist motion is usually slight. Synovial fluid tracking from the STT joint along the flexor carpi radialis (FCR) tendon sheath may form a ganglion cyst just proximal to the wrist crease. STT osteoarthritis should be suspected when a ganglion cyst is seen at this site in an older individual. Rarely, osteophytes at the margins of the scaphotrapezial joint irritate the flexor carpi radialis tendon or flexor pollicis longus tendon, causing tendinitis or rupture.

Loss of articular surface height in the scaphotrapezial and/or scaphotrapezoid joints is the earliest sign of STT osteoarthritis. Later, subchondral sclerosis, osteophytes and cysts appear (Figure 6.2.6). Oblique views are useful in showing the scaphotrapezial and trapeziometacarpal joints.

Splintage and analgesic medication are the first line of treatment. Steroid injection may be given through dorsal or palmar approaches, and be guided by fluoroscopy if necessary. Non-operative treatment is sufficient for most cases.

Arthrodesis of the STT joint is appropriate for isolated STT osteoarthritis. The joints are approached through a dorsoradial incision, avoiding branches of the superficial radial nerve. The alignment of the scaphoid and the spatial relationship of the three bones should be preserved, so as to avoid distortion of surrounding joints. Cancellous bone graft from the distal radius is packed between the decorticated surfaces and the bones are fixed together with pins, screws, or staples (Figure 6.2.7). If pins are used, their ends should be left under the skin and removed later under local anaesthesia, to avoid the risk that pin-track infection will lead to septic arthritis. Good pain relief is usually achieved. However, complications are frequent (20–30%), including superficial radial neuroma, pin-track infection, and non-union. The postoperative range of wrist motion is approximately 75% of normal. Excision of the distal scaphoid is an alternative but the long-term results are unknown.

When both STT and trapeziometacarpal joints are involved, the trapezium should be excised. It may also be useful to undercut the scaphotrapezoid joint to minimize the risk of persistent pain from the scaphotrapezoid joint.

The pisiform is a sesamoid bone that lies within the flexor carpi ulnaris tendon and articulates with the triquetrum. Pisotriquetral osteoarthritis may be idiopathic or due to fractures of the pisotriquetral articular surfaces or instability of the pisotriquetral joint. It may also be associated with associated with loose bodies in the pisotriquetral joint and with entrapment or irritation of the ulnar nerve.

Pain over the palmar/ulnar surface of the wrist is the hallmark of pisotriquetral arthritis. Pain is frequently aggravated by flexion or ulnar deviation of the wrist. Local tenderness is present over the pisiform. Pain and crepitus may be elicited by compression and mediolateral movement of the pisiform against the triquetrum. Signs of ulnar nerve entrapment should be sought.

Sclerosis of the pisiform may be apparent as an increase in density on the PA radiograph, but the joint is shown best on a 20-degree supinated oblique view or via computed tomography (CT). Osteophytes, sclerosis, and loss of articular cartilage height are seen on the underside of the pisiform and the adjacent surface of the triquetrum (Figure 6.2.8).

Steroid injection through an ulnar approach can reduce pain substantially, though the effect may be short-lived.

Excision of the pisiform is effective in relieving pain. It should be performed through a palmar or ulnar approach, protecting and, if necessary, decompressing the ulnar nerve and preserving the continuity of the flexor carpi ulnaris tendon. Excision does not appear to reduce wrist function significantly.