Definition

Primary osteoarthritis (OA) of the wrist refers to the painful degeneration of the articular surfaces that make up the wrist joint due to non-inflammatory arthritides. It commonly affects the joints between the distal radius and the proximal row of carpal bones. Symptoms include pain, swelling, stiffness, and crepitation. Radiographs will reveal different degrees of joint space narrowing, cyst formation, subchondral sclerosis, and osteophyte formation. OA in the wrist is rare. The Framingham study showed a 9-year incidence of only 1% of radiographically significant wrist OA in women, and 1.7% in men. These rates are significantly lower than the rates of thumb basal joint OA (30%), distal interphalangeal (DIP) joint arthritis (28% to 35% in patients over the age of 40), and radiographic hand OA in patients 80 years and older (90% to 100%).

Secondary OA of the wrist joint is the most common form of wrist OA, most commonly resulting from post-traumatic conditions, such as distal radius fractures, carpal fractures, and carpal instability. Rare conditions that may cause secondary wrist OA include idiopathic osteonecrosis of the lunate (Kienböck disease) and the scaphoid (Preiser disease). Distal radius fractures that have healed inappropriately (malunited) can also be the cause ( Fig. 40.1 ). Malunion occurs in approximately 23% of nonsurgically and 11% of operatively treated distal radius fractures. In considering malunited fractures of the distal radius, abnormal parameters that have been shown to be associated with wrist arthritis include the following: on an anteroposterior radiograph, an intra-articular step-off of more than 2 mm and radial shortening of more than 5 mm; or on the lateral radiograph, a dorsal angulation of more than 10 degrees. Articular step-off followed by loss of height have been found to be the two most important factors associated with wrist arthritis out of these parameters.

Anteroposterior (A) and lateral (B) plain radiographs of wrist osteoarthritis secondary to a malunited wrist fracture. Note the dorsal angulation of the distal articular surface and the reduced joint space. This patient also had significant osteopenia secondary to pain-induced lack of use.

Carpal fractures that fail to heal, particularly of the scaphoid, can also be the cause of arthritis. This bone is predisposed to nonunions biologically because of its fragile vascular supply and biomechanically on account of the shear forces it encounters. Other factors associated with nonunions include fracture displacement, fracture location, and delay in initiation of treatment. Features of a scaphoid nonunion that appear to be associated with arthritis are the displacement of the cartilaginous surfaces and the loss of carpal stability. Both of these lead to abnormal loading of the cartilage and consequently to ensuing arthritis. This pattern of arthritis is known as scaphoid nonunion advanced collapse (SNAC).

Carpal instability can also result in uneven loading of the articular surfaces and subsequent arthritis ( Fig. 40.2 ). The most common form of carpal instability is scapholunate dissociation. It consists of a disruption of the interosseous ligament between the scaphoid and lunate. The resultant abnormal biomechanics lead to abnormal loading and subsequent arthritis, a pattern known as scapholunate advanced collapse (SLAC).

Anteroposterior (A) and lateral (B) plain radiographs of wrist osteoarthritis secondary to scapholunate advanced collapse, stage 2. Note the increased scapholunate space and the sclerosis of the radioscaphoid joint. Early osteophytes are clearly seen on the radial border of the scaphoid. The lateral view shows dorsal osteophytes as well as the dorsally angled lunate.

Symptoms

Wrist pain is the presenting symptom in the overwhelming majority of patients. For the most part, this pain is of insidious onset, although many patients will recall a particular event that brought it to their attention. It is diffusely located across the dorsum of the wrist. It may be activity related and may bear little correlation to radiographic findings. Patients may also report inability to do their daily activities because of weakness, but on further questioning, this weakness is often secondary to pain. Pain tends to be intermittent and waxes and wanes over time.

Another presenting symptom is stiffness, particularly in flexion and extension of the wrist. Pronation and supination are usually not affected, unless the arthritic process is extensive and also involves the distal radioulnar joint. In some patients, motion may be associated with a clicking sensation or with audible crepitation. Complaints about cosmetic deformity are also common, particularly after distal radius fractures that have healed with an inappropriate alignment. Swelling is commonly noted by patients. This swelling is essentially a representation of the malunited fracture, but in patients with advanced arthritis irrespective of the etiology, it may represent synovial hypertrophy or osteophyte formation. In this situation, the swelling tends to be located in the dorsoradial region of the wrist.

Physical Examination

In general, comparison of the affected side with the contralateral extremity, if it is not involved, is useful to appreciate changes in the affected limb. Examination of the wrist includes a thorough examination of the entire upper limb, starting with the shoulder. Other sources of joint pain and loss of motion should be noted. Visual inspection of the wrist and upper extremity can reveal swelling and deformity, if present. Next, motion, strength, and sensory function should be tested. In wrist OA, the most obvious finding may be loss of motion. Normal range of motion of the wrist joint includes approximately 80 degrees of flexion, 60 degrees of extension, 20 degrees of radial deviation, and 40 degrees of ulnar deviation. Loss of grip strength may be evident, especially in patients with decreased radial inclination, which theoretically affects the function of the finger flexors biomechanically due to a change in the position of the carpal tunnel, through which the finger flexors run. The strength of the abductor pollicis brevis is tested by asking the patient to palmarly abduct the thumb against resistance. Similarly, the strength of the first dorsal interosseus muscle should be checked by asking the patient to radially deviate the index finger against resistance. These tests evaluate for motor deficits of the median nerve and ulnar nerve, respectively. Sensation should also be compared with the opposite side. Whereas static two-point discrimination is an excellent way to test sensation in the office, a more precise evaluation of early sensory deficits can be performed by graduated Semmes-Weinstein monofilaments. Frequently, this test requires a referral to occupational therapists who perform it.

Next, the wrist is palpated for evidence of tenderness or masses, such as cysts. Tenderness just distal to Lister tubercle may be a sign of pathologic change at the scapholunate joint, including scapholunate dissociation, Kienböck disease, or synovitis of the radiocarpal joint. Tenderness at the anatomic snuffbox may indicate a scaphoid fracture or nonunion, and in early SNAC, this may be the site of radioscaphoid degeneration. In the presence of pancarpal arthritis, the tenderness is usually diffuse.

Provocative maneuvers should also be performed to check for signs of carpal instability. The scaphoid shift test of Watson evaluates for scapholunate instability. In this test, the examiner places a thumb volarly on the patient’s scaphoid tubercle, and the rest of the fingers wrap around the wrist to lie dorsally over the proximal pole of the scaphoid. As the wrist is taken from ulnar deviation to radial deviation, the thumb will apply pressure on the scaphoid tubercle and force the scaphoid to sublux out of its fossa dorsally in ligamentously lax patients as well as in those with frank scapholunate instability. Once pressure from the thumb is released, the scaphoid will then shift back into its fossa and is accompanied by pain experienced by the patient. At times, an audible or palpable clunk will be appreciated as the scaphoid reduces. This finding is best demonstrated in patients who have ligamentous laxity or in patients with recent injuries. Patients who have chronic injuries often develop sufficient fibrosis to prevent subluxation of the scaphoid out of its fossa. However, they often still have pain that is reproduced with this maneuver. Comparison with the unaffected side is essential, especially if the patient has evidence of generalized ligamentous laxity.

Functional Limitations

The majority of the limitations in wrist arthritis arise from a lack of motion. A range of motion from 10 degrees of flexion to 15 degrees of extension is required for activities involving personal care. The loss of motion mainly affects activities of daily living such as washing one’s back, fastening a brassiere, and writing. Eating, drinking, and using a telephone require 35 degrees of extension. However, learned compensatory maneuvers can allow most activities of daily living to be accomplished with as little as 5 degrees of flexion and 6 degrees of extension.

Diagnostic Studies

The initial evaluation of the arthritic wrist includes standard posteroanterior, lateral, and pronated oblique radiographs. In the posteroanterior view, any evidence of arthritis between the radius and proximal row of carpal bones or between the proximal and distal rows should be noted. Radiographic features that indicate an arthritic process include reduction or loss of joint space, osteophyte formation, cyst formation in periarticular regions, and loss of normal bony alignment (see Fig. 40.2 ).

Injury to the scapholunate ligament is evidenced by a space between the scaphoid and the lunate greater than 2 mm and a cortical ring sign of the scaphoid. Sclerosis or collapse of the lunate is consistent with Kienböck disease. The lateral view can reveal signs of carpal instability, such as a dorsally or palmarly oriented lunate. In the lateral view, an angle between the long axes of the scaphoid and the lunate in excess of 60 degrees is also consistent with scapholunate dissociation. The oblique view will often demonstrate the site of a scaphoid nonunion. Although it may be possible to make a diagnosis of scapholunate dissociation on plain radiographs, some patients can often have bilateral scapholunate distances and angles in excess of normal limits. It is therefore critical to obtain contralateral radiographs before a diagnosis of scapholunate injury is made.

Patterns of arthritic progression in SLAC and SNAC wrists have been classified into three stages. In a SLAC wrist, stage 1 involves arthritis between the radial styloid and the distal pole of the scaphoid; stage 2 results in reduction or loss of joint space between the radius and the proximal pole of the scaphoid; and stage 3 indicates capitolunate degeneration with proximal migration of the capitate between the scaphoid and lunate. In a SNAC wrist, stage 1 and stage 3 are similar to those in a SLAC wrist. However, in stage 2, there is degenerative change between the distal pole of the scaphoid and capitate.

Other imaging modalities are not necessary for the diagnosis of OA. Computed tomography is sometimes used to evaluate the alignment of the scaphoid fragments in cases of nonunion and the amount of collapse of the lunate in Kienböck disease. Magnetic resonance imaging is occasionally used to evaluate the vascularity of the scaphoid proximal pole and lunate in scaphoid nonunions and Kienböck disease, respectively. Wrist arthroscopy offers the optimal ability to assess the condition of the articular cartilage; however, this assessment can be made from plain radiographs or at the time of surgical reconstruction of the wrist.

Differential Diagnosis

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