Metacarpophalangeal Joint Arthroplasty in Rheumatoid Arthritis

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1 Metacarpophalangeal Joint Arthroplasty in Rheumatoid Arthritis Joseph A. Abboud, MD, Pedro K. Beredjiklian, MD, and David J. Bozentka, MD Abstract Although metacarpophalangeal joint arthroplasty is occasionally performed for joints affected by osteoarthritis, it is most often done in patients with rheumatoid arthritis. The metacarpophalangeal joint is critical for proper finger function but is the most common site of involvement in the rheumatoid hand. A thorough understanding of the anatomy, pathophysiology, and mechanics of the metacarpophalangeal joint is a prerequisite for the evaluation and treatment of patients requiring metacarpophalangeal arthroplasty. Silicone rubber implants are the most frequently used device for treatment of revised metacarpophalangeal arthroplasty. Follow-up studies show that this surgery improves function and deformity and achieves nearly uniform patient satisfaction. J Am Acad Orthop Surg 2003;11: Rheumatoid arthritis (RA) is a chronic, progressive, systemic inflammatory disease that affects multiple organ systems, including the musculoskeletal system. Although its etiology is still incompletely understood, evidence for an immunemediated mechanism is mounting. 1 The inflammatory process is triggered and perpetuated by a cascade of mediators that result in synovial proliferation, collagenous destruction of the cartilage and soft tissues, and bone resorption. Even though RA can affect any synovial joint, the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints of the hand typically are involved early. In fact, the MCP joint is the most commonly affected joint in the rheumatic hand 2 (Fig. 1). Anatomy The normal MCP joint is a diarthrodial, condylar-type joint that allows flexion, extension, radial/ulnar deviation, and circumduction. The metacarpal head is asymmetric in both the coronal and sagittal planes. The radial condyle of the metacarpal head is larger than the ulnar condyle, which causes the metacarpal head to slope ulnarly and proximally in the coronal plane, especially in the index and long metacarpals. The volar surface of the metacarpal head is longer and broader than its dorsal surface, which accounts for the cam effect that tightens the collateral ligaments when the joint is flexed. 3 The contour of its articular segment gives the MCP joint a mobile center of rotation, which allows it to move volarly with flexion. The normal synovial membrane of the MCP joint is attached around the periphery of the articular cartilage with volar and dorsal synovial reflections. The synovial fold is largest dorsally on the neck of the metacarpal. 4 The normal range of motion of the MCP joint is from neutral to 90 of flexion, although many individuals display hyperextension up to approximately There is also some radial and ulnar deviation, which decreases with flexion and the associated tightening of the collateral ligaments. The extensor mechanism has limited attachments to the proximal phalanx via the dorsal capsule and extends the MCP joint through the sagittal bands. 3 The sagittal bands help extend the MCP joint through their insertion into the volar plate, and they center the extensor mechanism over the joint (Fig. 2, A). The ulnar sagittal bands are stronger and denser than the radial sagittal bands. 6 The intrinsic musculature provides flexion, abduction, and adduction of the MCP joint. 7 The interosseal and lumbrical muscles exert their forces on the joint through their attachments into the extensor hood and proximal phalanx. Dr. Abboud is Resident, Department of Orthopaedic Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA. Dr. Beredjiklian is Assistant Professor, Department of Orthopaedic Surgery, Division of Hand Surgery, University of Pennsylvania School of Medicine. Dr. Bozentka is Assistant Professor, Department of Orthopaedic Surgery, and Chief, Division of Hand Surgery, University of Pennsylvania School of Medicine. Reprint requests: Dr. Beredjiklian, Presbyterian Medical Center, 39th and Market Streets, 1 Cupp Pavilion, Philadelphia, PA Copyright 2003 by the American Academy of Orthopaedic Surgeons. 184 Journal of the American Academy of Orthopaedic Surgeons

2 Joseph A. Abboud, MD, et al Figure 1 A and B, Rheumatoid hand demonstrating characteristic deformities of volar subluxation and of the digits at the MCP joints. The volar plate supports the MCP joint volarly and limits its extension. The membranous portion of the volar plate attaches to the metacarpal neck and has more laxity than its distal insertion. The cartilaginous portion of the volar plate is distal and attaches firmly to the base of the proximal phalanx. The volar plates of adjacent digits are interconnected by the fibers of the deep transverse intermetacarpal ligament. 3 The accessory collateral ligaments lie volar to the radial and ulnar collateral ligaments. The accessory ligaments extend from below the collateral ligament at the metacarpal head to the volar plate and are thought to stabilize it. 8 The radial and ulnar collateral ligaments, which lie dorsal to the center of rotation of the MCP joint, reinforce the joint. These ligaments are lax when the joint is extended and, because of the cam effect, become taut when the joint is flexed. They are also asymmetrical, especially at the index MCP joint. The ulnar collateral ligament is more nearly parallel with the longitudinal axis of the finger than is the radial collateral ligament, which has a more oblique orientation. 9 When the joint is flexed, supination of the finger relaxes the radial collateral ligament, allowing it to run a less oblique course. Therefore, the index and long fingers allow increased ulnar deviation of the MCP joint with the joint in both flexion and supination. Pathoanatomy Rheumatic involvement of the MCP joint begins as a proliferative synovitis that progresses to volar subluxation and ulnar deviation of the digits, resulting in eventual destruction of the joint s articular surfaces. It is unclear whether disrupting the static supports of the articulation leads to the dynamic imbalance or vice versa, but both play a role in the resulting deformity 4 (Fig. 2, B). Articular cartilage softening and erosion diminish the structural integrity of the metacarpal head, removing effective support for and resulting in a static imbalance of the PIP joint. 3 As the disease progresses, disruption of the subchondral surface and structural bony elements of the joint lead to misalignment of the articular segment. Several factors have been implicated in the development of the deformity. (1) Asymmetry of the metacarpal head (larger radial condyle) leads to ulnar deviation of the MCP Figure 2 A, Normal anatomy of the MCP joint. B, MCP joint deformities with rheumatoid arthritis. CL = collateral ligaments, ET = extensor tendon, FT = flexor tendon, FTS = flexor tendon sheath, IM = interosseous muscle or tendon, IML = intermetacarpal ligament, L = lumbrical, MH = metacarpal head, PP = proximal phalanx, SB = sagittal bands, VP = volar plate. (Adapted with permission from Wilson RL, Carlblom ER: The rheumatoid metacarpophalangeal joint. Hand Clin 1989;5: ) Vol 11, No 3, May/June

3 Metacarpophalangeal Joint Arthroplasty in Rheumatoid Arthritis joints with progressive flexion. (2) Carpal collapse leads to radial deviation of the carpus and metacarpals and to compensatory ulnar deviation of the digits. (3) Attenuation of the radial sagittal band secondary to synovial proliferation within the joint causes ulnar subluxation of the extensor mechanism. 4,5,9 (4) Volar subluxation or rupture of the extensor mechanism potentiates the flexion forces of the intrinsic and flexor tendons, resulting in volar subluxation of the proximal phalanx. 3,10 (5) Synovial proliferation results in attenuation of the accessory collateral ligaments and the membranous portion of the volar plate, leading to ulnar and volar displacement of the proximal portion of the flexor sheath from the midline. The displaced flexor tendon results in an abnormal force on the proximal phalanx, furthering the ulnar and volar displacement of the articular segment. 3,6 (6) Rheumatic synovitis produces changes within the interosseal muscles. Interosseal muscle contractures lead to a volar-directed force on the MCP joint, again contributing to volar subluxation. 11 The rheumatic wrist joint also contributes to MCP deformity. Wrist synovitis weakens the volar wrist ligaments, leading to volar flexion of the scaphoid and associated radial deviation deformity. At the distal radioulnar joint, synovitic stretching of the ulnar carpal and distal radioulnar ligaments leads to dorsal dislocation of the distal ulna, supination of the carpus on the hand, and volar subluxation of the extensor carpi ulnaris muscle 12,13 (Fig. 3). Ulnar drift of the MCP joints in RA occurs more commonly in patients with radial deviation of the wrist than in patients without it. 14 Clinical Assessment Assessing global function and the deformities of the adjacent joints is Figure 3 Posteroanterior radiograph of a rheumatoid hand demonstrating subchondral cysts, osteopenia, and volar subluxation of MCP joints with ulnar deviation. critically important in evaluating candidates for MCP joint arthroplasty. Hand surgery, if indicated, should be timed appropriately. 6 In general, lower extremity and more proximal upper extremity procedures should be done before hand surgery. Cervical spine involvement is common in patients with RA, particularly in those with long-standing disease and multiple joint involvement. 15 Nearly one third of patients have unstable cervical joints, with atlantoaxial subluxation being the most common instability. Radiculopathy and myelopathy secondary to cervical spine instability must be differentiated from a peripheral compression neuropathy. Cervical stability must be assessed before surgical intervention in the upper extremity, especially if general anesthesia with endotracheal intubation is being considered. Because deformities in the proximal joints should be corrected before distal articulations are addressed, evaluation of the shoulder, elbow, and wrist is necessary in candidates for MCP joint arthroplasty. An axiom for surgery in patients with RA is to start proximally and work distally, alternating fusion with motionsparing procedures. 6 Addressing the radial deviation wrist deformity is very important before MCP joint arthroplasty because progression of at the MCP joints after arthroplasty is inevitable in patients with significant wrist involvement. In addition, distal radioulnar joint instability can result in attritional extensor tendon ruptures. Focusing solely on the MCP joint can lead to unsuccessful surgical outcomes. Rheumatic involvement of the PIP and distal interphalangeal joints also must be assessed because their function is coupled to the mechanical properties of the MCP joint. Swan-neck and boutonnière deformities are common, occurring respectively in 14% and 36% of patients with RA. 16 Unlike other distal joints, PIP joints may be treated either after or at the same time as the more proximal MCP joints. 11,17 Most surgeons prefer to retain motion at the MCP joints while gaining stability and optimal position at the PIP level. Implant arthroplasties of both the MCP and PIP joints are rarely indicated. 18 Rather, the preferred approach is to perform MCP implant arthroplasties and correct the PIP joint problems with either tendon reconstruction (for flexible deformities) or arthrodesis (for fixed deformities). In addition to assessing associated joints, the status of the flexor and extensor tendons also should be evaluated for the presence of synovitis and potential rupture. The severity of tenosynovium proliferation around the extrinsic flexor tendons should be noted because this may limit the amount of tendon excursion, leading to limited MCP joint motion. With concomitant extensor tendon rupture, synovectomy and extensor tendon repair should precede MCP joint arthroplasty by 6 to 8 weeks. 19 Some surgeons, 186 Journal of the American Academy of Orthopaedic Surgeons

4 Joseph A. Abboud, MD, et al however, perform both the MCP joint arthroplasty and the extensor tendon reconstruction at the same time because it is difficult to tension the tendon reconstruction properly when the MCP joints are dislocated. 19 Figure 4 Larsen radiographic scale for grading joint involvement in RA using standard reference films. Grade 0: no change. This signifies a normal joint without changes related to arthritis. Grade I: slight changes, including periarticular swelling. Grade II: erosions, with definitive joint-space narrowing. Grade III: medium destructive changes with erosions and joint spaces poorly defined. Grade IV: severe destructive changes and collapse with significant erosions. Grade V: mutilating changes. The original articulating surfaces have disappeared, and there is gross bony deformation. (Adapted with permission from Wilson RL, Carlblom ER: The rheumatoid metacarpophalangeal joint. Hand Clin 1989;5: ) Classification of Joint Deformity The deformities of the MCP joint can be classified in stages, as described by Millender and Nalebuff. 20 This grading system correlates well with the radiographic grading system of Larsen et al 21 for RA joint involvement 6 (Fig. 4). Stage I (Larsen grade I) represents early RA with MCP joint synovitis. The patient retains the ability to fully extend the joint, with few bony or articular changes and little ulnar deviation present. Patients can be treated with occasional splinting and/or corticosteroid injection to relieve symptoms. Night splints to hold the MCP joints in extension and correct ulnar deviation also can be used. Stage II (Larsen grade II) is marked by the development of early bony erosions. In this stage, chronic synovitis can lead to stretching of the radial sagittal bands, resulting in the ulnar subluxation of the extensor tendons over the metacarpal head. An extensor lag is common, but flexion is preserved. Pain is usually the primary complaint. Clinical intervention focuses on maximizing treatment. Surgery at this stage may consist of soft-tissue realignment procedures in select cases and synovectomy. Synovectomy is not thought to alter long-term prognosis of the disease but is considered to result in temporary symptom improvement. 15 Stage III (Larsen grades III to IV) is characterized by progression of articular surface destruction and an increase in the ulnar deviation and volar subluxation deformities. At this stage, nonoperative management typically is ineffective, and patients with pain and functional disability often require surgery. Surgical options include tendon centralization and synovectomy or silicone interposition arthroplasty. Stage IV (Larsen grades IV to V) is marked by fixed malalignment of the articular segment and destruction of the articular surface of the MCP joint. Resection arthroplasty with flexible implants is widely considered to be the treatment of choice. Indications for Arthroplasty Advanced arthritis of the MCP joint requiring surgery is uncommon, except in the rheumatic hand. Because the number of published studies of MCP arthroplasty in osteoarthritis or posttraumatic arthritis is limited, specific indications have not been well established. The general indications for MCP arthroplasty in patients with RA are painful deformity with destruction or subluxation of the joint and fixed deformity that cannot be corrected with soft-tissue reconstruction alone. Implant arthroplasty is indicated in patients with (1) decreased arc of motion ( 40 ), (2) marked flexion contractures with the joint fixed in poor functional position, (3) MCP joint pain with associated radiographic abnormalities, and (4) severe (>30 ). 6 In a relatively young (<50 years) patient with a functional range of motion of the MCP joint (active arc, 60 to 70 ), surgical intervention should be considered carefully because it may produce little functional improvement. Contraindications to surgery include the presence of vasculitis, poor skin condition, or inadequate bone stock. Excessive erosion of the metacarpal head and proximal phalanx or excessive fatty replacement of the cancellous bone may make prosthetic fit unsuitable, and the implant may rotate. 22 Surgical Technique The techniques for resection arthroplasty of the MCP and other digital joints, with and without prosthetic components, have been well researched. 11,12,14 The earliest techniques for soft-tissue arthroplasty were followed by the introduction of cup arthroplasty and the metallic hinged prosthesis. 28,29 The Swanson silicone rubber implant was developed in the 1960s. Despite some drawbacks, the modified Swanson implant remains the most reliable and accepted for replacement arthroplasty in the hand. 30 The flexible silicone rubber implant used for MCP arthroplasty differs in fixation, articulation, and motion from other joint replacement prostheses 31 (Fig. 5 ). The various implants do not function as true prostheses but serve as dynamic spacers Vol 11, No 3, May/June

5 Metacarpophalangeal Joint Arthroplasty in Rheumatoid Arthritis Figure 5 Silicone rubber MCP joint implants. A, Swanson implant (Wright Medical, Arlington, TN). B, Neuflex implant (DePuy, Warsaw, IN). C, Sutter implant (Avanta Orthopaedics, San Diego, CA). to maintain the joint alignment after resection. 22 The pistoning or gliding of the implant within the medullary canal is thought to add to the range of motion achieved by the arthroplasty and to disperse the forces along the implant-bone interface. 5,31 The technique for MCP arthroplasty has been described extensively A pneumatic tourniquet is placed in the proximal arm and set to 250 mm Hg. The extremity is exsanguinated with a compression bandage. A dorsal transverse incision is made at the junction of the metacarpal head and neck (Fig. 6, A). The dorsal veins should be preserved to minimize postoperative digital swelling. The extensor mechanism is exposed, and a longitudinal incision is made in the extensor hood. Swanson 31 and others make this incision on the ulnar aspect of the hood, although Beckenbaugh and Linscheid 30 recommend preserving the ulnar hood, if possible, and incising the radial aspect of the extensor mechanism. The capsule is then incised longitudinally, and the neck of the metacarpal is exposed. Soft-tissue release is necessary to relocate the phalanx and to allow preparation of the bony structures for insertion of the components. The collateral ligaments are released subperiosteally at their origins, and the contracted ulnar intrinsic muscles, including the abductor digiti minimi manus, are released with a blade. The flexor digiti quinti brevis manus is preserved because achieving active flexion postoperatively in the small finger is most difficult. In an attempt to preserve the function of the first palmar interosseous muscle in pinch, some surgeons prefer not to release the ulnar intrinsic muscle to the index finger. After the metacarpal neck is transected with a saw or rongeur, the metacarpal head is removed along with capsular attachments. The level of resection is just distal to the origin of the collateral ligaments and perpendicular to the axis of the metacarpal shaft. Any synovial proliferation can be removed at this time by flexing or distracting the joint. The medullary canal of the metacarpal is then reamed with a hand reamer. A trial prosthesis is selected, and the largest prosthesis possible is fitted without applying excessive force. 36 An appropriately sized prosthesis should fit snugly while the transverse midportion of the implant rests against the cut surface of the bone (Fig. 6, B). After the articular cartilage is removed at the base of the proximal phalanx, a perforation is made in the subchondral bone in line with the center of the medullary canal. With a rasp or burr, the hole is enlarged to accept a rectangular prosthesis. The proximal phalanx of the index finger is reamed in a supinated position to allow for better tip pinch postoperatively. In contrast, the proximal phalanx of the small finger is reamed in slight pronation to improve grip. After preparation and reaming, the trial prosthesis is again inserted to assure proper fit and reassess soft-tissue balance. With placement of a properly sized Figure 6 MCP joint arthroplasty. A, Dorsal transverse incision over the MCP joint with careful retraction of soft tissue and preservation of dorsal veins. B, An appropriately sized prosthesis, shown here fitting comfortably into the metacarpal. C, Posteroanterior postoperative radiograph. 188 Journal of the American Academy of Orthopaedic Surgeons

6 Joseph A. Abboud, MD, et al Table 1 Long-term Follow-up of Swanson MCP Implant Arthroplasty Study No. of Implants Follow-up (mo) Mean (Range) Swanson (6 to 60) Beckenbaugh et al 32 (12 to 65) Madden et al >24 Blair et al (24 to 125) Bieber et al 33 (24 to 96) Kirschenbaum et al 35 (60 to 195) Hansraj et al (24 to 120) Gellman et al 43 prosthesis, there should be no subluxation of the joint, and the implant should fit snugly into both canals (Fig. 6, C). Some authors advise using implants with titanium grommets to improve durability. Theoretically, the titanium protects the silicone rubber from wear. However, no studies have documented clinical benefit of their use, and data from animal experiments are inconclusive. 37 Before the chosen prosthesis is inserted, preparations are made for softtissue reconstruction of the radial ligament complex. Two small (0.035 in) drill holes are made on the dorsoradial aspect of the metacarpal neck for subsequent reattachment of the radial collateral ligament. A4-0 nonabsorbable braided suture is placed through the holes. If the collateral ligament is severely attenuated, an alternative radial ligamentous reconstruction may be done, with the volar capsule and half of the volar plate attached to the origin of the collateral ligament. 23,30 Mean Postoperative Arc of Motion Recurrent Deformity 60 < % mixed deformities 57 < % mean 43 7 mean 27 N/A mean N/A = not available. (Adapted with permission from Stirrat CR: Metacarpophalangeal joints in rheumatoid arthritis of the hand. Hand Clin 1996;12: ) Kirschenbaum et al 35 have described good long-term results without radial reconstruction. The bony surfaces are then irrigated and prepared for implantation. A so-called no-touch technique is used with smooth forceps so as not to injure the surface of the silicone rubber because implant fracture has been related to propagation of surface defects. The implant is inserted into the metacarpal first; then, with flexion and distraction, the distal end is placed into the phalanx. The collateral ligament suture is repaired to the metacarpal, and the dorsal hood is repaired by imbricating or reefing the radial sagittal band to realign the extensor tendon. The skin is closed with interrupted 5-0 nylon sutures over a subcutaneous drain. Unnecessary trauma to the skin during closure is to be avoided. A bulky dressing is applied, and the hand is splinted with the MCP joints in extension and the digits in mild radial deviation to protect the soft-tissue reconstruction. 5 The drain can be removed on postoperative day 1. The dressings are removed on postoperative day 2 or 3, and rangeof-motion exercises are started 1 week postoperatively. A dynamic extension splint and a night resting splint are used for the first 6 weeks to help maintain neutral or slight radial deviation of the digits. The goals of the dynamic splinting program are to control alignment, maintain range of motion, and limit undesirable forces on the soft-tissue reconstruction. Concomitantly, the patient is enrolled in therapy to encourage active range of motion of all digital joints. The dynamic splint is discontinued after 6 weeks, but the resting splint can be used for 3 to 4 months. In therapy, special attention is devoted to the small finger, which may achieve active flexion more slowly than the others because of the release of the hypothenar intrinsic muscles, and to the index finger, which has a greater tendency to than do the others. 38 Postoperative Results The results of MCP arthroplasty are well documented (Table 1), and postoperative function appears to improve in appropriately selected patients. 5 Realistic expectations are important because patients are not likely to achieve full range of motion of the MCP joint. In patients with a substantial extensor lag or ulnar deviation, the arc of motion may be only minimally increased, but this will be in a more functional extended position. Key and tip pinch also should improve because the index finger is brought over into radial position. Reported mean postoperative arcs vary from 27 to ,39-44 Extension lags also vary, from 9 to ,40-44 A loss of approximately 12 of active motion from an early postoperative arc of motion of 51 has been documented at a mean follow-up of 63 months. 33 Vol 11, No 3, May/June

7 Metacarpophalangeal Joint Arthroplasty in Rheumatoid Arthritis Ulnar deviation can be reliably corrected, although there is a tendency for some to recur over the long term Nevertheless, correcting the deformity has been shown to be a major contributor to a patient s subjective sense of improvement. 30,31,34 Most series show correction to within a few degrees of neutral. 31,33,34 Recurrent has been reported in up to 43% of patients. 30 The recurrent deviation, however, is usually <10 ; fewer than 10% of patients will have a recurrence >30. 22,31,32,34,35,43-45 Recurrence of deformity correlates with a more severe disease course. Pain relief is consistently documented in follow-up studies of MCP joint arthroplasty. Kirschenbaum et al 35 reported that of 144 arthroplasties in 36 hands, none of the patients complained of pain, although Bieber et al 33 reported that 20% of patients in their series complained of pain preoperatively. Beckenbaugh et al 32 reported recurrence of pain in 2% of patients at a mean follow-up of 32 months. Because the rates of pain recurrence are low, overall patient satisfaction rates are consistently high. Silicone rubber MCP joint implants are associated with low rates of complications. 41 Several other types of MCP prostheses have been associated with generally higher rates of long-term complications. 40,46-48 In a review of complications of Swanson finger joint implants, Foliart 41 reported that the most frequently reported complication was change in the bone surrounding the implant, found in 4% of silicone rubber implants. Swanson et al 49 found that metacarpal midshaft cortical bone consistently decreased postoperatively and that the length of the metacarpals with implants in place decreased an average of 9%. Bone remodeling also resulted in thickening of the bony surfaces at the metacarpal and phalangeal metaphysis while maintaining the shape of the cut end of the metacarpal. 49 The bone resorption is likely related to the immunogenic response of macrophages to silicone rubber particulate debris. However, silicone particle disease does not appear to be a critical issue for silicone MCP joint arthroplasty. Implant fracture rates average 2% of cases (range, 0% to 38%). 41 In most cases, however, implant fracture does not require revision of the prosthetic component. Many authors report that most patients with fractured implants have acceptable function and do not require revision surgery. This was shown in a study evaluating the Sutter implant, which had a higher fracture rate than the Swanson implant, although there was no correlation between implant fracture and patient satisfaction. 46 Morbidity associated with the fractured prosthesis is low because it functions as a spacer rather than as an articulated prosthesis. 50 Several changes have been made in the implants to address this problem. Improvements in silicone rubber have led to enhanced resistance to fracture and tear propagation in vitro. Infection is rare, seen in 0.1% to 1% of reported implants. 32,35,40,41 Foliart 41 noted infection in 0.6% of implants. Millender et al 51 noted that all infections presented within 8 weeks of implantation. Staphylococcus aureus was the most common organism isolated. In most cases, the prosthesis had to be removed, and an average of 2 weeks of antibiotic treatment was required. 51 Particulate synovitis and siliconeinduced lymphadenopathy have received substantial attention. Foliart 41 reported both of these complications in 0.1% of cases. Synovitis in MCP implants occurred almost exclusively in fractured implants or in implants with substantial signs of wear at removal. Summary The MCP joint is critically important for hand function, and when it is affected by RA, severe deformity and loss of function commonly occur. Treatment options include management with medications and splinting, synovectomy, soft-tissue procedures, or implant arthroplasty. The choice is based on the patient s symptoms and severity of involvement. After MCP arthroplasty, patients typically can expect correction of deformity and effective pain relief. Recurrence of mild deformity because of occurs in a substantial percentage of patients. Implant fracture remains a concern, although the incidence likely has been reduced with the improved quality of silicone rubber. Longevity and reliable function beyond 10 years, however, have yet to be documented. Despite only slight improvement in the arc of motion, most patients are satisfied with silicone implant arthroplasty because of improved cosmesis and function and the reduction in pain. References 1. Arend WP, Dayer JM: Cytokines and cytokine inhibitors or antagonists in rheumatoid arthritis. Arthritis Rheum 1990;33: Roberts WN, Daltroy LH, Anderson RJ: Stability of normal joint findings in persistent classic rheumatoid arthritis. Arthritis Rheum 1988;31: Smith RJ, Kaplan EB: Rheumatoid deformities at the metacarpophalangeal joints of the fingers. J Bone Joint Surg Am 1967;49: McMaster M: The natural history of the rheumatoid metacarpo-phalangeal joint. J Bone Joint Surg Br 1972;54: Journal of the American Academy of Orthopaedic Surgeons

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