6.5 Rheumatoid arthritis of the hand and wrist

The hands and wrists are frequently affected in rheumatoid disease. Function can be impaired by painful acute inflammation of joints or by their later destruction. Involvement of tendons can lead to rupture, bulky synovitis may cause secondary nerve compression syndromes, and painful subcutaneous nodules may interfere with use of the hands.

Disease-modifying drug therapy has reduced referrals to surgeons for treatment of persistent acute inflammation of joints and tendon sheaths. Early synovectomy of joints is effective in relieving pain but does not appear to protect them from destruction over the long term. However, the benefit of tenosynovectomy of flexor and extensor tendons is frequently long lasting.

Patients generally present to the surgeon in the late stage of rheumatoid disease. Requests for surgical advice may be for one or more of the following problems:

Assessment of the rheumatoid hand and wrist should involve not only ‘look, feel, move, and radiograph’ but also an assessment of function. A systematic approach is essential to avoid being distracted by obvious cosmetic deformities. Functional deficits may be due to joint disease, but the equally important effects of tendon rupture, nerve compression, and cervical radiculopathy should not be forgotten.

Patients should be asked how far they can reach with the hand—to the mouth, to the top of the head, to the natal cleft. These abilities are strongly influenced by disease at the elbow and shoulder. They should also be asked what they can do with the hand in these positions. Can they feed, dress, and attend to personal hygiene independently? Does disease of the lower limbs compel the patient to bear weight with the hands through a stick or crutch? Questions about common activities of daily living will identify specific functional problems and help to determine the surgical priorities.

Inspection of the hand should note the deformities, which frequently reflect zigzag compensatory phenomena such as flexion contracture of the proximal interphalangeal joint accompanied by fixed hyperextension of the distal joint (boutonnière deformity). Deformities may be in more than one plane (Figure 6.5.1). Ulnar deviation at the metacarpophalangeal joints is frequently associated with palmar subluxation and pronation (especially in the index finger). Palpation will detect residual synovitis and signs of active disease in joints and tendon sheaths. Sensory testing is useful in detecting peripheral nerve entrapment; motor testing is more difficult as weakness and wasting may be due to disease in adjacent joints.

Movement is the most detailed part of the examination and must include the following:

Radiographs may show far greater bone and joint destruction than the functional assessment and examination had suggested. Radiographic abnormalities are not themselves an indication for surgery but are useful in determining the surgical options that are available (e.g. joint destruction precludes synovectomy).

Assessment by an occupational therapist experienced in rheumatoid disease can be most helpful, by observing the patient in a simulated home and kitchen environment, by selecting aids which may improve function, and by clarifying the need (or lack of need) for surgery.

Medical assessment includes degree of control of disease activity and monitoring of drug treatment, especially for ‘new’ drugs such as anti-tumour necrosis factor (TNF)-alpha agents for which temporary withholding of the drug is advised by manufacturers over the course of major surgical procedures.

The priorities for treatment of the rheumatoid hand and wrist are pain relief and restoration of function. Cosmetic improvement would be regarded as a bonus but is seldom an indication for surgery on its own. The patient’s expectations of outcome should be assessed carefully, bearing in mind that surgery often relieves pain but is much less effective at improving strength and movement. Unrealistic expectations should be corrected by counselling before surgery is undertaken. Not every patient with deformed hands needs surgery. Young patients whose lifestyle is affected by mild disease should be advised to modify their activities. Older patients who have minimal pain and satisfactory function despite deformity will not be improved by surgery.

Relief of pain is the most common indication for surgery at the wrist. A painful wrist will prevent good use of the hand, even if the fingers and thumb are in good condition. A painful thumb will affect many everyday actions, especially if it is also unstable. Souter emphasized that surgery of the rheumatoid hand and wrist should begin with simple and reliable procedures, so that the patient’s confidence is gained, before moving on to less predictable operations. Provision of a pain-free wrist and stabilization of the thumb are top of Souter’s list.

Assessment of the wrist should attempt to localize pain to the radiocarpal joint, to the distal radioulnar joint, or to both joints. The site of local tenderness and the provocation of pain by flexion/extension and forearm rotation are useful.

In the thumb, stability is more important than movement. When hand function is compromised, the thumb should be regarded as a stable ‘post’ against which the fingers can act. When finger movement is also limited, key pinch to the side of the index finger may be the only achievable type of pinch. It is acceptable to fuse the metacarpophalangeal joint and the interphalangeal joints of the thumb if its basal joint is mobile. An iliac crest graft may be needed to maintain length in cases of severe bone loss. Surgery of the painful subluxed basal joint will fail and basal subluxation will recur unless secondary web contractures and fixed deformities of more distal joints are corrected at the same time.

In the fingers, the priority is to maintain movement at the base of the digit. In severe cases, movement at the metacarpophalangeal joints and stability of the interphalangeal joints in a functional position may be all that can be achieved. In less severe cases, surgical correction at the metacarpophalangeal joints (e.g. by silastic interposition arthroplasty) may give good finger function, especially where the metacarpophalangeal joints are diseased but the interphalangeal joints are spared. Stiffness of the proximal interphalangeal joints in hyperextension (swan-neck deformity) can severely limit grip even if the metacarpophalangeal joints are mobile; surgical correction is often helpful. However, stiffness of the proximal interphalangeal joints in flexion is compatible with good power grip and seldom needs surgery.

Tendon rupture is a potentially preventable cause of functional loss in rheumatoid disease and merits careful assessment. Early clearance of persistent tenosynovitis and elimination of bony spicules will reduce the risk of rupture of additional tendons. The ruptured tendon should be regarded as diseased and not suitable for direct repair. Reconstruction is by transfer of a synergistic intact tendon, by side-to-side suture to an adjacent intact tendon, or, occasionally, by tendon graft. Fusion is sometimes simpler and more appropriate than tendon transfer (e.g. interphalangeal joint of thumb after flexor pollicis longus tendon rupture). The cause of rupture (e.g. ulnar head) should be treated to eliminate the risk to other tendons, even if tendon reconstruction is impracticable.

Loss of function caused by sensory deficiency secondary to nerve compression can often be improved by nerve decompression. For median nerve compression at the wrist, synovectomy of the flexor tendons should be added if there is obvious bulky synovitis.

A stable pain-free wrist is essential for good function of the hand. Although the wrist is seldom the first joint affected by rheumatoid disease, it is ultimately affected in over 90% of patients with severe arthritis. Surgery is frequently required to deal with pain, weakness, and instability of the rheumatoid wrist and distal radioulnar joint.

In the acute stage of pain and swelling, pain is frequently due to synovitis of the overlying flexor and extensor tendons rather than to disease in the wrist joint itself. In these cases, swelling and local tenderness will follow the synovial tendon compartments, which extend proximal and distal to the wrist joint. Tenosynovectomy (see later) may be useful. However, open synovectomy of the wrist joint is technically impracticable because of the many small joints and the difficulty in reaching their palmar recesses through a dorsal approach. Chemical synovectomy may be considered, or arthroscopic synovectomy may be performed.

In cases of continued pain with minimal destruction, wrist denervation has been used successfully and detailed descriptions of the techniques are available. Preoperative assessment by local anaesthetic blocks of all nerves supplying the wrist is mandatory. The author has found denervation useful in juvenile rheumatoid arthritis, where painful stiffness is a greater problem than joint destruction.

Two patterns of deformity are commonly seen in the stage of late destruction of the wrist and distal radioulnar joint. The carpus may supinate on the forearm, with translation of the extensor carpi ulnaris tendon over the axis of flexion/extension so that it ceases to act as an extensor of the wrist. The ulnar head becomes prominent dorsally. In other cases, destruction of the distal radius affects the palmar surface more than the dorsal surface, leading to palmar subluxation of the carpus.

Distal radioulnar pain may arise from synovitis alone, from destruction of the joint surfaces, or from loss of radial length with impingement of the ulnar head on the carpus. Persistent synovitis with healthy joint surfaces is an occasional indication for distal radioulnar synovectomy. More often, joint damage will be obvious and surgical correction will require excision of the ulnar head (Darrach procedure). Just enough bone should be removed to clear any impingement against the sigmoid notch of the radius. The level of excision is just proximal to the articular surface. The ulnar stump should remain within the distal radioulnar joint capsule, which should be repaired as securely as possible. Painful instability of the ulnar stump, which is very difficult to treat, may occur if too much bone is excised. Subluxation of the extensor carpi ulnaris tendon should be corrected, so as to rebalance the wrist and stabilize the ulnar stump. This is performed using part of the proximal half of the extensor retinaculum as a ‘sling’ (see ‘Extensor tenosynovectomy’section).

The results of ulnar head excision are much more satisfactory and predictable in rheumatoid arthritis than in post-traumatic disorders. Progressive ulnar translation of the carpus may occur after ulnar head excision. Although it is probably due more to softening of radiocarpal ligaments by disease (Figure 6.5.2) than to loss of support of the ulna, ulnar carpal translation is a contraindication to ulnar head excision. The presence of spontaneous radiolunate fusion, or a shelf of bone projecting toward the ulna from the lunate fossa of the radius, protect against ulnar carpal translation. Radiolunate fusion may be performed at the time of ulnar head excision in patients who are thought to be at risk of carpal translation because of limited radiolunate contact or excessive radial inclination.

An alternative to ulnar head excision is the Sauvé–Kapandji procedure, in which the ulnar head is fused to the sigmoid notch of the radius and a segment of distal ulnar shaft is excised to allow rotation through the resulting pseudoarthrosis. Although a stable radioulnar surface is provided, the procedure may not prevent ulnar carpal translation. Instability of the proximal ulnar stump may cause troublesome impingement against the shaft of the radius.

Arthrodesis and arthroplasty are the surgical options for the severely damaged radiocarpal joint. Excision arthroplasty has been unsatisfactory in rheumatoid disease. Swanson silastic interposition arthroplasty has a high failure rate by fracture and bone resorption over the longer-term failures are seen particularly in patients who load the wrist heavily or who gain a large range of motion. Silastic arthroplasty remains a satisfactory procedure for patients with low demands and well-balanced wrists, aiming to achieve no more than 30 degrees each of flexion and extension, but is now rarely performed.

Cemented metal on polyethylene total wrist arthroplasties have been beset with problems of bone resorption, fracture, loosening, and infection. Cementless implants and improved methods of rebalancing wrist tendons may help to improve the results. Salvage of failed arthroplasties remains difficult because of the loss of bone stock. All wrist arthroplasties bridge the midcarpal joint but many do not ‘line up’ with the normal anatomical 20–24 degrees of radial inclination and 10-degree volar inclination of the radiocarpal joint so must have a propensity to fail because of shear stresses. Many designs have had to be withdrawn from the market because of unacceptable early and medium-term failure rates.

Total arthrodesis provides excellent stability and relief of pain in the rheumatoid wrist in cases where arthroplasty is inappropriate or contraindicated (Figure 6.5.3) Arthrodesis is also indicated for salvage of failed arthroplasties. In the patient with severe bilateral wrist disease, a total arthrodesis will provide stability and freedom from pain on one side while a motion-preserving procedure (arthroplasty or limited wrist fusion) will retain some flexibility on the other side. However, many patients function very well with bilateral wrist fusions and are pleased with the stability and relief of pain. When considering the indication for bilateral fusion, the movement of the elbow, shoulder, and forearm rotation should be taken into account; a functional assessment by an occupational therapist may be invaluable. At least one wrist should be fused in neutral, rather than slight extension, so as to permit perineal hygiene.

Total wrist arthrodesis is achieved much more easily in rheumatoid disease than in post-traumatic arthritis. Simple fixation with a Steinmann pin from the third metacarpal into the radius will suffice. An additional wire or staple is sometimes needed to control rotation. The porotic bone and poor soft tissue envelope of most rheumatoid wrists do not lend themselves to fixation by plates. In wrists with marked palmar subluxation, the gain in length achieved by fusion may improve power in the finger tendons. Fusion in juvenile rheumatoid patients is occasionally needed for pain relief and correction of gross deformity but risks limiting growth of the distal radius. Splinting and wrist denervation should be attempted for pain relief before considering fusion.

Synovitis involving the flexor and extensor tendons is common in rheumatoid disease. It is more obvious on the extensor surface, particularly on the back of the hand where the tenosynovium extends beyond the distal limit of the extensor retinaculum and may produce a sizeable swelling. The swelling extends proximally but is less evident beneath the unyielding extensor retinaculum.

Flexor tenosynovitis produces less obvious swellings, but restriction of active movement and crepitus as bulky tendons move beneath pulleys are common. The swelling is seldom visible or palpable beneath the flexor retinaculum, but appears in the palm, distal forearm, and digits. Restriction of active flexion, or persistent pain and stiffness in the presence of healthy joints, should always raise the suspicion of flexor tenosynovitis, even if swelling is minimal. Median nerve compression secondary to flexor tenosynovitis may cause pain without the sensory symptoms which characterize its presentation in the non-rheumatoid patient.

The consequences of tenosynovitis are pain, restricted active motion, and tendon rupture. Two mechanisms cause tendon rupture: destruction of tendon fibres by invading synovial tissue, and attrition on rough bony prominences. Typically, the extensors of the fingers are abraded sequentially by the ulnar head. A bony spicule protruding from the scaphotrapezial joint into the carpal canal may damage the flexor pollicis longus tendon, followed by the profundus tendon of the index finger, the superficialis tendon of the index finger, and the profundus tendon of the middle finger.

Rupture of extensor tendons causes drooping at the metacarpophalangeal joints and loss of active extension. Provided that the metacarpophalangeal joint is healthy, passive extension is normal. Two important differential diagnoses may mimic extensor tendon rupture. Subluxation of the extensor tendon to the ulnar side of the metacarpophalangeal joint diminishes its power so that it cannot extend the joint actively from the flexed position. However, if the joint is extended passively, the tendon returns to its normal position and can maintain the extended position. Rarely, loss of active metacarpophalangeal joint extension is due to compression of the posterior interosseous nerve by synovitis around the radial neck. A complete palsy is usually obvious, but partial lesions may affect only one or two extensor muscles. As the wrist is flexed, the viscoelasticity of the paralyzed muscles pulls the metacarpophalangeal joints into extension, whereas the metacarpophalangeal joints will remain drooped if the tendons have ruptured.

Unfortunately, the occurrence of tendon ruptures does not correlate well with pain or tenosynovial swelling. The patient with profuse extensor tenosynovitis is certainly at risk of rupture. Dorsal wrist pain on active resisted finger extension may signify impending rupture. However, ruptures which are due to attrition on bone frequently occur without warning or pain. Ruptures of the extensor digiti minimi and flexor digitorum superficialis tendons may pass unnoticed by patient or doctor, but their detection is vital because they indicate that other ruptures may be imminent.

The indications for extensor tenosynovectomy are tenosynovitis which persists after appropriate medical management and incipient or actual tendon rupture. In common with other wrist operations in rheumatoid disease, a straight longitudinal dorsal wrist incision is preferred because it minimizes the risks of skin necrosis and dorsal sensory nerve damage. It can be reopened for subsequent wrist operations as necessary. The essential steps are removal of diseased tenosynovium, excision of bony spurs (e.g. ulnar head), and replacement of part or all of the extensor retinaculum beneath the tendons to protect them from later disease in the wrist joint. The third, fourth, and fifth compartments are frequently involved and should be opened routinely. Tenosynovectomy of the second and sixth compartments may also be necessary. The first compartment is seldom involved.

The frequency of rupture of the extensor tendons in a review of 202 cases was as follows: extensor pollicis longus, 20%; extensor digitorum (little), 17%; extensor digitorum (ring), 15%; extensor digitorum (middle), 7%; extensor digitorum (index), 2%; flexor pollicis longus, 12%; flexor digitorum profundus (index), 7%.

The ruptured tendons are not amenable to direct repair as their stumps are diseased and have retracted. Reconstruction is generally by transfer of an intact and expendable tendon into the ruptured tendon (Figure 6.5.4), but a tendon graft may be used if the original muscle is in good condition and no expendable tendon is available for transfer.

Commonly used transfers are shown in Table 6.5.1. The wrist extensor tendons can be used for transfer if the wrist is fused, but their excursion is limited and they may be too short to reach the distal tendon stumps.

The indications for flexor tenosynovectomy are persistent painful tenosynovitis, incipient or actual tendon rupture, median nerve compression in the carpal canal, and triggering. As in the extensor system, timely tenosynovectomy is vital in preventing tendon rupture and preserving function of the hand.

At the wrist, the tendons are exposed by dividing the flexor retinaculum and extending the incision proximally and distally as necessary. The diseased tenosynovium is removed from the musculotendinous junction to the lumbrical insertion, taking care to minimize retraction of the median nerve. The floor of the carpal tunnel is inspected for bone spicules, which most commonly arise from the scaphotrapezial joint. Spicules are excised and the capsule repaired by direct suture or local capsular flap.

Segments of the digital flexor sheath can be exposed through transverse or zigzag incisions. Tenosynovitis is seen most often beneath the A1 pulley and just distal to the A2 pulley (Figure 6.5.5), but can affect the entire sheath. Diseased synovium and intratendinous nodules are excised. Release of the A1 pulley in rheumatoid disease is controversial, as it may allow ulnar migration of the flexor tendons and aggravate ulnar drift deformity of the metacarpophalangeal joints. Some surgeons prefer to decompress the digital sheath by excision of the ulnar slip of the superficialis tendon, a procedure that achieves decompression at the A2 as well as at the A1 pulley and which removes any possibility of entrapment of the flexor digitorum profundus tendon between the two slips of the superficialis tendon.

The management of flexor tendon rupture is also controversial. Rupture of flexor pollicis longus requires prompt exploration of the carpal canal and removal of the cause of rupture (osteophyte from the scaphotrapezial joint or invasive tenosynovitis), to prevent rupture of other tendons. Active flexion of the interphalangeal joint can be restored by transfer of a superficialis tendon, but the range of motion thus gained is usually small. Fusion of the interphalangeal joint in slight flexion is often preferred in the weak hand of the rheumatoid patient, as it gives a stable thumb with good power transmitted from the short muscles.

Loss of both tendons within the digital sheath is disabling but reconstruction is difficult. Transfer of the flexor digitorum superficialis tendon from another finger can be used if a healthy distal flexor digitorum profundus stump is present; otherwise tendon grafting may be necessary despite its unpredictable outcome.

Options for reconstruction of ruptured flexor tendons are shown in Table 6.5.2. The results of tendon reconstruction are dependent on the number and level of the ruptures. Full active flexion is seldom regained.

Many factors have been implicated in the production of ulnar deviation at the metacarpophalangeal joints. Synovitis at the metacarpophalangeal joint causes distension of the joint capsule and stretching of the collateral ligaments. The lax joints are then vulnerable to malalignment under the influence of muscle and other forces. The main factors appear to be the strong forces applied by the flexor tendons, which produce palmar subluxation, and by the thumb, which exerts pressure on the sides of the fingers during grip and pinch. If movement of the fingers is painful, the thumb may become the main source of functional grip and its use for key pinch against the sides of the fingers, rather than ‘tripod’ pinch to the tips, may deform the lax metacarpophalangeal joints. Subluxation of the extensor tendons and tightness of the ulnar intrinsic muscles are commonly seen in ulnar deviated fingers, but whether they are a contributory cause or a consequence of ulnar drift is uncertain (Box 6.5.7). Ulnar drift at the metacarpophalangeal joints is also associated with radial deviation deformity of the wrist, but again it is unclear if the wrist deformity is a cause or a consequence of ulnar drift. It is clear, however, that surgical correction of ulnar drift will fail if fixed radial wrist deviation is not also corrected.

The early stages of metacarpophalangeal joint synovitis are amenable to medical management. Synovectomy is effective in relieving pain and swelling that have persisted after appropriate medical treatment, but probably does not alter the course of the disease. Synovectomy may be performed in isolation or in combination with soft tissue reconstruction.

Synovectomy and soft-tissue reconstruction are indicated when synovitis is associated with passively correctable ulnar deviation and well-preserved joints without palmar subluxation. Subluxation of extensor tendons to the ulnar side of the metacarpophalangeal joint often occurs at this stage. The reconstruction may require release of tight intrinsic muscles, centralization of extensor tendons, reefing of lax radial collateral ligaments, and transfer of ulnar intrinsic tendons to the radial side of the adjacent digit (crossed intrinsic transfer). The intrinsic tendon may be attached to the radial aspect of the proximal phalanx, to the fibrous flexor sheath, or to the radial lateral band. Ulnar deviation of the index finger may be improved by reefing the tendon of the first dorsal interosseous muscle.

The extensor tendon is centralized by reefing of the radial sagittal bands and, if necessary, release of tight ulnar sagittal bands. Alternatively, a distally based strip of extensor tendon can be passed palmar to the deep transverse metacarpal ligament and sutured back to the remaining tendon. This type of reconstruction may cause some limitation of extension but it is effective in securing the alignment of the tendon (Figure 6.5.6). Persisting ulnar deviation may be improved by reefing of the radial collateral ligaments, but at the risk of some loss of metacarpophalangeal joint movement.

The essence of postoperative management is to allow early motion but protect against ulnar deviation forces until the soft tissues have healed. If the reconstruction is secure, protection in a static splint between exercise sessions for 6 weeks is sufficient. Alternatively, a dynamic extension outrigger splint supports the metacarpophalangeal joints in extension and radial deviation but allows flexion.

Metacarpophalangeal arthroplasty is required for fixed ulnar deviation, palmar subluxation, and metacarpophalangeal destruction. Excision arthroplasty does not provide stability and may be followed by progressive loss of bone stock. Hinged and other total replacement arthroplasties have a high rate of early failure. The gold standard is the Swanson silastic flexible implant arthroplasty. A fibrous capsule forms around the implant, which pistons freely in the medullary cavities and acts as a spacer which maintains length and supports the soft-tissue reconstruction.

Not all patients with metacarpophalangeal joint destruction require metacarpophalangeal joint arthroplasty. The best indications are relief of pain and correction of deformity which is interfering with function. Moderate ulnar drift is compatible with satisfactory function, particularly if metacarpophalangeal joint pain is modest and interphalangeal movement is good.

Silastic metacarpophalangeal arthroplasty has given consistent and predictable relief of pain and improvement of ulnar deviation. The active flexion range at long-term review is 35–55 degrees. Mild recurrence of ulnar deviation may occur over several years, depending partly on the rate of progression of the disease. Particulate silicone synovitis is rare around metacarpophalangeal joint implants. Fracture of the implant occurs but does not necessarily cause symptoms or necessitate removal of the implant.

Metacarpophalangeal arthroplasty is performed through a single transverse or multiple longitudinal incisions. The metacarpal head is removed at a level just distal to the origin of the collateral ligaments. Release of the ulnar collateral ligament may be needed if ulnar deviation is severe. Release of the palmar plate may also be necessary. It is vital that sufficient space is created to accept the implant without buckling on flexion and extension. The medullary canals are reamed to accept the largest implant which will fit comfortably.

The implant provides a flexible and stable base for the soft-tissue reconstruction, which is vital to the success of the operation. The reconstruction may include intrinsic release, crossed intrinsic transfer, and extensor realignment. The radial collateral ligament may require reefing or, if it is deficient, reconstruction using the radial half of the palmar plate.

Postoperative management aims to encourage the formation of a soft tissue envelope which allows flexion/extension but is stable from side to side. Dynamic splintage, as described earlier for synovectomy and soft-tissue reconstruction, is widely used. However, crossed intrinsic transfer may remove the need for dynamic splintage.

The proximal interphalangeal joint is a hinge joint which allows motion from 0–120 degrees. The stout collateral ligaments and palmar plate confer good lateral stability and resistance to hyperextension. Synovitis of the proximal interphalangeal joint produces a spindle-shaped swelling of the finger and rapidly limits movement. Synovectomy is indicated for persistent painful synovitis in the face of adequate medical therapy. Access is limited and may require incisions between the central slip and the lateral band on each side. The incisions are closed securely to prevent palmar migration of the lateral bands.

Deformity of the proximal interphalangeal joint is common in rheumatoid arthritis and is usually in the sagittal plane. It reflects disturbance of the delicately balanced muscle and tendon systems which act across the proximal interphalangeal joint.

Swan-neck deformity is hyperextension at the proximal interphalangeal joint and flexion of the distal interphalangeal joint. It results from imbalance in the tendon systems which cross the proximal interphalangeal joint and is generally due to weakening of a tendon insertion or static joint restraint by diseased synovium. Because the three joints are interdependent though their tendon and ligament systems, swan-neck deformity can be caused by synovitis at any one of the three finger joints. Swan-neck deformity can occur only if hyperextension is possible at the proximal interphalangeal joint.

Proximal interphalangeal joint synovitis weakens the palmar plate and superficialis insertion, allowing hyperextension of the proximal interphalangeal joint. Later, the lateral bands migrate dorsally as the transverse retinacular ligaments elongate and a secondary extension lag appears at the distal interphalangeal joint.

Destruction of the terminal tendon of the dorsal aponeurosis by synovitis at the distal interphalangeal joint may also initiate swan-neck deformity. Without the attachment of the terminal tendon, the dorsal aponeurosis migrates proximally and pulls excessively on the central slip, resulting in hyperextension of the proximal interphalangeal joint.

Flexion deformity at the metacarpophalangeal joints is often associated with swan-neck deformity. Many factors may be involved, including intrinsic muscle contracture.

Swan-neck deformity has been graded into four types, depending on the mobility of the proximal interphalangeal joint and the condition of the joint surfaces.

The disability of swan-neck deformity is due mainly to lack of flexion of the proximal interphalangeal joint. If the proximal interphalangeal joint is mobile, it may ‘lock up’ in hyperextension and flex with a snap as flexion effort is increased and the lateral bands slide from dorsal to palmar over the sides of the joint.

Type I swan-neck deformity may require no treatment. Locking of the proximal interphalangeal joint in extension (Figure 6.5.7) can be prevented by blocking hyperextension with a figure-of-eight splint. If a thermoplastic splint is effective, a more durable splint may be constructed from metal and worn like a ring. Hyperextension may also be corrected by tenodesis across the palmar aspect of the proximal interphalangeal joint, using one slip of the superficialis tendon which is detached proximally and sutured to the A2 pulley. Alternatively, the lumbrical tendon can be rebalanced as a flexor of the proximal interphalangeal joint. Fusion of the distal interphalangeal joint may also be useful, particularly when the swan-neck deformity is due to elongation of the terminal tendon.

Type II deformity is due to tightness of the intrinsic muscles. Proximal interphalangeal joint flexion is limited when the metacarpophalangeal joint is extended but normal when the metacarpophalangeal joint is flexed (the intrinsic tightness test). The restriction is often increased by deviation of the metacarpophalangeal joint to the radial side, showing that the tightness is greater on the ulnar side. A distal intrinsic release is performed, excising a triangle of the dorsal aponeurosis which includes the ulnar lateral band and adjacent oblique fibres. A tenodesis or tendon rebalancing may be required, as for type I.

If the swan neck deformity was initiated at distal interphalangeal joint level as a ‘mallet finger’ fusion of the terminal joint in a position just short of full extension may need to be added.

Type III deformity prevents grasp because the proximal interphalangeal joints are fixed in extension. Passive flexion is prevented by soft tissue contracture which may involve the dorsal aponeurosis, the dorsal capsule of the proximal interphalangeal joint, and the skin. The lateral bands are fixed dorsally and cannot slide toward the palm to allow flexion. Manipulation of the proximal interphalangeal joint may restore flexion in less severe cases. An oblique skin release over the middle phalanx may be needed if the skin blanches on flexion. The joint can be stabilized temporarily with a pin across the joint. This procedure may be useful in psoriatic arthropathy, where the finger joints characteristically become stiff at an early stage without marked joint destruction. Mobilization of the lateral bands from the central slip may be needed in more severe cases. These procedures may be performed at the same time as metacarpophalangeal joint arthroplasty.

Type IV deformity is best managed by arthrodesis (see later). In selected patients, Swanson or pyrocarbon arthroplasty of the proximal interphalangeal joints can be considered, provided that tendon imbalance is corrected. Arthroplasty should be restricted to the proximal interphalangeal joints of the ring and little fingers, which require flexion for power grip. The index and middle fingers are also used for tripod pinch to the tip of the thumb; stability of pinch is more important than additional flexion in these digits. Aids such as large-handled cutlery can mitigate the effects of loss of flexion.

Arthrodesis of the proximal interphalangeal joint should be performed using a technique that gives stable fixation, allows early movement of other joints, and does not require plaster immobilization. Tension band wire fixation provides stable fixation without unduly prominent metalwork (Figure 6.5.8) and avoids protruding pins with their inconvenience, risk of infection, and need for removal before fusion is secure. Care must be taken to preserve the cancellous bone of the head of the proximal phalanx; excessive resection exposes the hard cortical bone of the neck and may delay union. The angle of fusion depends on the digit and the range of motion of other joints in the hand. The angles usually selected are: index 35 degrees; middle 45 degrees; ring 55 degrees; and little 65 degrees.

Arthrodesis of the distal joint is performed in a few degrees of flexion, though greater flexion may be required to accommodate to deformity of other joints or for specific functional needs. Tension band fixation is stable and avoids protruding pins, but an oblique K-wire and interosseous wiring technique is easier in these small joints. Fixation with a Herbert screw is also effective (Figure 6.5.9).

Boutonnière deformity comprises flexion of the proximal interphalangeal joint and hyperextension of the distal joint. It is compatible with surprisingly good function in the rheumatoid hand, especially if some flexion is possible at the distal joint (Figure 6.5.10). Boutonnière deformity in the fingers always results from disease at the proximal interphalangeal joint, leading to destruction of the central slip. The lateral bands migrate in a palmar direction, where they become fixed by contracture of the transverse retinacular ligament. In this position, they no longer act to extend the proximal interphalangeal joint and their pull on the distal joint is excessive. Unfortunately, the results of soft tissue reconstruction of rheumatoid boutonnière deformity are unsatisfactory. If surgery is needed, it should be fusion of the proximal interphalangeal joint in a functional position. Tenotomy of the extensor tendon over the middle phalanx may improve the range of flexion of the terminal joint in less severe cases.

Lateral deformities and instability of the proximal interphalangeal joint are usually due to joint destruction; arthrodesis in a functional position is the only way to improve grip. In cases of mutilating arthritis with multiple joint destruction, loss of length, and instability, the principle is to provide stable fingers in the best functional position with movement concentrated at the base of the finger. It may be necessary to fuse both proximal and distal interphalangeal joints.

The joints of the thumb are frequently affected by rheumatoid disease. Any of the three joints can be affected. The thumb is used in nearly all daily activities and the complaint is almost always of painful interference with function rather than of pain alone. The loss of pinch strength is frequently associated with instability of one or more joints. Repeated loading of the distended and inflamed joints leads to failure of the ligaments and to deformity. As in the fingers, the interdependence of the joint mechanisms results in a zigzag posture in which the failure of one joint leads to opposite deformity of adjacent joints.

Deformities of the thumb fall into three patterns.

A more complicated classification into six types has been proposed by Nalebuff and others, but the scheme listed here describes the great majority of thumb deformities.

In considering treatment, the thumb must be regarded as providing a stable post against which the fingers can work to provide pinch grip. Mobility is needed at the basal joint so that the thumb can be positioned appropriately. At the metacarpophalangeal and interphalangeal joints, stability is more important than movement. Therefore instability at these joints should be managed by arthrodesis in 0–20 degrees of flexion. In the author’s opinion, silastic interposition arthroplasty has no place in the treatment of the rheumatoid thumb.

Arthrodesis of the interphalangeal joint of the thumb is performed by a tension band wiring technique through an S-shaped dorsal incision with care to protect the nail-bed. At the metacarpophalangeal joint, the bones are large enough to use a ‘chevron’ method in which a V-shaped notch is made in the head of the metacarpal and the base of the proximal phalanx is trimmed to fit it. The large surfaces of cancellous bone will fuse rapidly and can be held with K-wires at 90 degrees to each side of the V in a crossed-wire configuration. Alternatively, a tension band wire technique can be used, as in the proximal interphalangeal joint of the finger (Figure 6.5.11). In the case of marked bone loss in mutilating arthritis, it may be necessary to fuse both metacarpophalangeal and interphalangeal joints to maintain length or indeed to gain length by interposing corticocancellous grafts from the iliac crest. This apparently drastic surgery can improve function remarkably and help to maintain the patient’s independence for dressing, cooking, and eating.

In the swan-neck thumb, the primary abnormality is usually at the basal joint. The aim of providing mobility at the base of the thumb precludes fusion. Trapezial excision arthroplasty with stabilization of the metacarpal base using a distally-based strip of the flexor carpi radialis tendon is effective and straightforward. Release of the contracted muscles of the thumb web and correction of metacarpophalangeal joint hyperextension by arthrodesis may also be necessary.

Nodules on the hand are more than a cosmetic problem. They occur commonly on the dorsum of the proximal interphalangeal joint, where they are easily knocked, and in the pulps of the digits, where they cause pain and interfere with grip. Many patients have relatively little joint destruction and their function can be improved by removal of painful nodules. Excision under local or regional anaesthesia may be very helpful, but patients should be aware that the tendency to form nodules can continue for many years and many operations may be needed.