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Rheumatoid Arthritis of the Shoulder

Chen, Andrew L. MD, MS; Joseph, Thomas N. MD; Zuckerman, Joseph D. MD

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Journal of the American Academy of Orthopaedic Surgeons: January 2003 - Volume 11 - Issue 1 - p 12-24
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Abstract

Rheumatoid arthritis (RA) is a chronic, systemic inflammatory disorder of unclear etiology characterized by an erosive, symmetrical polyarthritis that may lead to progressive disability. The estimated prevalence is 1% worldwide, with a female-to-male ratio of 3:1 that diminishes with age. The prevalence increases starting in the third decade of life; RA affects more than 5% of the population older than 70 years. Approximately 91% of patients with long-standing RA (>5 years' duration) develop shoulder symptoms.1,2

Rheumatoid disease causes a microvascular injury and mild synovial cell proliferation, with perivascular lymphocytosis. The continued inflammation results in the formation of an erosive, hyperplastic synovium (pannus) as well as joint swelling (Fig. 1). Immune complex deposition and complement activation on the articular surfaces produce degradation of proteoglycans and collagen. The release of inflammatory cytokines results in continued cartilage damage, bone erosion, and soft-tissue degradation, often involving the insertion of the rotator cuff. In addition, through poorly understood mechanisms, chondrocytes themselves may play a role in articular destruction through possible participation in proteolytic digestion of cartilage matrix.3,4

Figure 1
Figure 1:
Low-power photomicrograph of pannus (a) eroding through articular cartilage (b), with invasion and destruction of subchondral bone (c) (hematoxylin-eosin, original magnification ×100).

Clinical Course

The initial presentation of RA is highly variable; however, more than 90% of patients report generalized symptoms of fatigue, musculoskeletal pain, variable fever, and weight loss.1,2 Some may present with joint pain alone, which may be monoarticular or polyarticular without systemic findings. Early involvement typically affects the small joints of the hand and foot. The knee, ankle, wrist, and elbow usually are involved later. Particularly in the early phases of the disease, the clinical course may be characterized by quiescence during periods of remission.

Rheumatoid involvement of the shoulder may present with an insidious onset of pain, swelling, and progressive loss of motion, reflecting both articular and periarticular involvement. Patients often are unaware of the early loss of motion, perhaps because of their ability to compensate with motion at adjacent joints or with the contralateral extremity. As motion loss progresses, the patient may find it difficult to reach previously accessible objects on high shelves or to perform activities behind the back, such as fastening a brassiere or obtaining objects from a back pocket. RA may affect all of the synovial joints of the shoulder region—the glenohumeral, acromioclavicular, and sternoclavicular joints. The scapulothoracic articulation (not a true synovial joint) may become secondarily affected as the involvement of adjacent joints progresses. Rheumatoid involvement of the shoulder often is associated with soft-tissue pathology. Seventy-five percent of patients with RA of the shoulder eventually have rotator cuff compromise, with 20% to 35% developing full-thickness tears.5

Evaluation

Physical Examination

Subcutaneous rheumatoid nodules may be present over the elbow, forearm, Achilles tendon, or other joints. Rales on inspiration or rubs with chest excursion may indicate pleuritis, pleural effusion, or pericardial effusion. Generalized swelling and warmth of the affected joint, with a variably sized effusion, are common findings. Range of motion may be diminished because of swelling and pain secondary to synovitis and capsular distension.

The patient with shoulder involvement typically holds the extremity at the side in a protective position. Initially, active motion may be limited by pain while passive motion is unaffected. As the process progresses, both active and passive motion become limited, leading to fixed contractures in all three important planes of motion— forward elevation, external rotation, and internal rotation. Muscle atrophy occurs as a result of rotator cuff involvement as well as disuse (Fig. 2). With progressive articular and osseous glenohumeral disease, painful crepitus will be evident.

Figure 2
Figure 2:
Atrophy of the shoulder girdle musculature, as well as subdeltoid/subacromial swelling, are evident in this patient with advanced rheumatoid disease of the shoulder.

The glenohumeral joint is symptomatic without associated acromioclavicular or sternoclavicular involvement in two thirds of cases.1 Painful cross-chest adduction is nonspecific and can indicate either glenohumeral or acromioclavicular disease. Tenderness to palpation of the acromioclavicular or sternoclavicular joints suggests involvement, as do warmth and swelling.

Subacromial or subdeltoid bursitis may occur in the absence of significant articular destruction and causes local pain and swelling. Bursitis may limit motion but will not cause fixed contractures, as seen with joint involvement.

Laboratory Evaluation

Patients without a history of RA should have a complete work-up for inflammatory or autoimmune etiologies (Table 1). Further testing, including HLA typing or serum protein characterization, generally is unnecessary during the initial stages of evaluation but may be done once the diagnosis of RA has been suggested.

Table 1
Table 1:
Laboratory Profile of a Patient With Rheumatoid Arthritis

Sterile aspiration of the glenohumeral joint may help differentiate RA of the shoulder from other etiologies. This is especially important in a patient with an inflamed, warm, tender shoulder in whom septic arthritis must be ruled out, particularly in the presence of a fever (Table 2).

Table 2
Table 2:
Comparison of Synovial Fluid Aspirates

Radiographic Evaluation

The earliest radiographic sign of rheumatoid involvement of the glenohumeral articulation is regional osteopenia of the humeral head or glenoid (Fig. 3, A). With disease progression, marginal erosions and cysts become apparent at the inferior margin of the humeral head, with subsequent involvement of the glenoid (Fig. 3, B). Humeral head erosions may be evident initially at the articular margins, at sites of soft-tissue insertion where inflammation is greatest (Fig. 3, C). These erosions may progress to involve large portions of the head, eventually resulting in areas of bone loss or even flattening of the head. Glenoid erosions can be central or peripheral. Superior migration of the humeral head may occur as a result of involvement of the rotator cuff, with eventual pseudoarticulation between the humeral head and the acromion process and erosion of the undersurface of the acromion extending into the acromioclavicular joint1,6,7 (Fig. 3, D). Although less commonly encountered, extensive destructive arthritis, or arthritis mutilans, can occur. Sclerosis is uncommon and usually reflects a later stage after the inflammatory component has subsided and secondary degenerative arthritis develops. Acromioclavicular involvement is a continuum, from subchondral osteopenia to marginal erosions to extensive osteolysis.

Figure 3 A,
Figure 3 A,:
Anteroposterior radiograph showing early changes of rheumatoid disease. Osteopenia, with minimal articular degenerative changes, and superior migration of the humeral head consistent with rotator cuff compromise are present. B, Intermediate changes of symmetric glenohumeral joint space loss and early cyst formation. C, As the disease progresses, more extensive erosions are evident about the humeral head and glenoid; progressive glenoid bone loss results in medialization of the humeral head. The superior migration of the humeral head indicates progressive rotator cuff deterioration. D, Extensive articular destruction, or arthritis mutilans, reflects end-stage changes with extensive erosions and bone loss.

Magnetic resonance imaging (MRI) is useful for demonstrating osseous, articular, and soft-tissue changes. Joint effusion, synovial inflammation, pannus formation, and capsular distension can be identified. The extent of rotator cuff involvement may be determined, ranging from inflammation to attenuation to extensive, full-thickness compromise. MRI is especially useful for the evaluation of shoulder weakness and pain not fully explained by bony changes seen on plain radiography.8

Computed tomography (CT) may be indicated when preoperative analysis of humeral head defects and glenoid articular erosions is necessary. Albertsen et al9 reported agreement between preoperative CT results and intraoperative findings, concluding that CT could characterize osseous defects and bone loss more accurately than can standard radiography (Fig. 4). This is particularly important in evaluating glenoid erosion to determine whether implantation of a glenoid component is possible.

Figure 4
Figure 4:
Axial CT views of the shoulder. A, Early involvement, with joint space narrowing (arrows) but maintenance of glenoid morphology. B, Later-stage changes showing significant glenoid bone loss and erosion (arrows) into the glenoid neck. C, Advanced changes, with extensive erosion (arrows) of the glenoid and humeral head.

Differential Diagnosis

Although RA is the most common inflammatory arthritis to affect the shoulder, its variable, nonspecific presentation may require that other conditions be excluded before the diagnosis can be established. Glenohumeral aspiration is often helpful (Table 2). Patients with septic arthritis often have high fever and local findings of erythema and swelling. Rotator cuff arthroplasty may be associated with anterosuperior instability and superior humeral migration, often with secondary erosive changes on the inferior aspect of the acromion and the acromioclavicular joint.

Crystalline arthropathies of the shoulder can have presentations similar to that of RA. An insidious onset of mild shoulder discomfort with low-grade inflammation accompanied by blood-tinged synovial fluid replete with debris, hydroxyapatite crystals, and few inflammatory cells (mostly monocytes) is indicative of Milwaukee shoulder (calcium hydroxyapatite crystalline arthropathy). Positive staining of crystals with alizarin red S confirms the diagnosis. Both gout (sodium urate crystal deposition) and pseudogout (calcium pyrophosphate dihydrate crystal deposition) may have articular cartilage calcifications but may be differentiated on synovial fluid examination; calcium pyrophosphate dihydrate deposition has positively birefringent rhomboid-shaped crystals, while gout has negatively birefringent needleshaped crystals.5,10,11

Osteoarthritis is the most common form of glenohumeral arthritis, affecting up to 80% to 85% of women older than 70 years.12 Osteoarthritis may be secondary to trauma or fracture, developmental dysplasia, or old sepsis, or may be a manifestation of “burned out” inflammatory arthritis. Its characteristic radiographic presentation shows asymmetric joint space narrowing, subchondral sclerosis, and osteophytes about the glenoid and humeral head (Fig. 5).

Figure 5
Figure 5:
Anteroposterior radiograph of an osteoarthritic glenohumeral joint shows subchondral sclerosis, cyst formation, humeral head flattening, and osteophyte formation. This classic appearance is readily distinguishable from the radiographic changes typical of RA (Figure 3).

Classification

The Laine classification of RA of the glenohumeral articulation has three stages based on clinical and radiographic findings.13 In stage I, slight limitation of shoulder motion is present, with mild to moderate pain and tenderness to palpation. Crepitation may be appreciated on range of motion. Radiographs show only generalized osteopenia. Stage II is characterized by moderate limitation of shoulder motion, moderate to severe pain, and crepitus. Radiographic findings include osteopenia, erosive bony changes, and joint space narrowing. In stage III, severe functional deficits are present; range of motion is painful and limits activities of daily living. Radiographs show advanced erosive changes of the humeral head and glenoid.13 Neer14 classified RA of the shoulder into three categories based on clinical and radiographic findings; his dry, wet, and resorptive stages are approximately equivalent to those of Laine et al.13

Nonsurgical Management

Nonsurgical management of the rheumatoid shoulder is indicated for mild to moderate (stage I) disease, when synovial inflammation is the primary manifestation before significant bony changes occur. The emphasis is on optimal use of medications (Fig. 6).

Figure 6
Figure 6:
Algorithm for treatment of RA of the shoulder.

Intra-articular Corticosteroid Injection

Intra-articular injection of corticosteroids for RA of the shoulder has been described for the treatment of acute and subacute inflammatory synovitis. Although the intra-articular administration of corticosteroids often may result in dramatic symptomatic relief, it should be considered as only a temporizing measure for patients who have not responded to oral medications. Multiple injections can have a deleterious effect on connective tissue structures, including the articular cartilage and the rotator cuff tendons, and therefore should be avoided.1,15 Most physicians suggest limiting injections to three and to consider repeat injections only when significant improvement has resulted from the previous injection.

Physical Therapy

Maintenance and/or improvement of shoulder motion may be enhanced by physical therapy consisting of passive and active-assisted range-of-motion exercises. During periods of active synovitis, motion should be maintained with assisted and passive motion exercises focusing on forward elevation, external rotation, and internal rotation behind the back. As the synovitis and inflammation improve, stretching can be initiated to improve the overall range of motion. Isometric exercises for the deltoid muscle and rotator cuff can effectively maintain muscle tone and strength during periods of exacerbation. With resolution of the acute episode, therapy can progress to include more rigorous strengthening and stretching to regain full range of motion. Ideally, exercises should be performed five times a day in 10-minute sessions rather than in one or two long sessions.

Surgical Management

Surgical management of the rheumatoid shoulder is indicated when medications and physical therapy are no longer effective in relieving pain and maintaining function. Selection of procedure is based on a careful assessment of the degree of involvement of the articular cartilage, subchondral bone, and periarticular soft tissues. Cartilage-preserving procedures are indicated when some articular cartilage remains intact and the goal is to prevent or slow disease progression by methods such as synovectomy. Cartilage-sacrificing procedures (eg, hemiarthroplasty, total shoulder arthroplasty, and arthrodesis) are indicated when articular cartilage loss is extensive and beyond preservation.

Basic Principles

Staging of Procedures

The polyarticular nature of RA often necessitates multiple surgical procedures. Most authors agree that the most disabling articulation should be addressed first;16-19 however, staging also depends on the nature of the procedures (eg, arthroscopic or open). Given equal symptomatology, opinions vary regarding prioritization of upper versus lower extremity. When shoulder surgery is done first, lower extremity procedures should be delayed at least 3 months to avoid weight bearing on the recovering shoulder. This period may be extended to more than 6 months to allow healing of additional soft-tissue procedures such as rotator cuff repair. When the lower extremity is addressed first, shoulder surgery should be delayed until assistive ambulatory devices are no longer necessary.

When multiple upper extremity procedures are necessary, the most symptomatic joint should be addressed first. In general, prioritization should be given to the procedure that results in the greatest functional improvement. Neer et al17 maintained that hand or wrist involvement should be addressed before ipsilateral elbow or shoulder disease because functional limitations of the hand or wrist may preclude rehabilitation of the elbow or shoulder due to a lack of incentive to use the involved upper extremity. Friedman and Ewald18 stated that the elbow should be addressed first; giving priority to surgical management of the elbow yields greater subjective and objective functional improvement of the upper limb and allows for a longer interval between arthroplasties. Gill et al19 reported that arthroplasty of both the shoulder and elbow for end-stage RA may be done successfully independent of the sequence of joint replacements. With multiple upper extremity involvement, technical considerations such as humeral component stem length in shoulder or elbow arthroplasty also must be taken into account in anticipation of future procedures.

Timing

The timing of surgical management should be dictated by the degree of symptoms and the clinical presentation. Early surgical intervention with synovectomy or bursectomy may be indicated for patients with only a diminished range of motion or a decreased subacromial space. Surgical intervention also may be based on the degree of bone loss rather than just pain and disability because further disease progression could preclude later reconstructive surgery.

Systemic Considerations

The systemic nature of RA requires careful multidisciplinary assessment before surgery. The cervical spine must be evaluated for stability before endotracheal intubation. Subtle myelopathy secondary to cord compression from C1-C2 instability may be mistaken for diffuse joint involvement resulting in weakness. Of particular concern are the possible need for perioperative corticosteroids, the increased risk of infection because of immunosuppression, and perioperative anemia.

Cartilage-Preserving Procedures

Bursectomy and/or synovectomy is indicated for patients with primarily active synovitis without evidence of extensive articular destruction. Although joint débridement may provide symptomatic relief in patients with soft-tissue swelling and evidence of inflammation, it seldom results in a significant increase in range of motion.20 Synovectomy also may be done in patients with rapidly progressing synovitis in an effort to slow disease progression. However, the results of synovectomy generally depend on the degree of articular cartilage involvement; the best results are obtained in patients with early (stage I) disease.1 Synovectomy may be either open or arthroscopic, with successful return to pain-free motion in up to 80% of patients.21 Arthroscopic glenohumeral synovectomy and subacromial bursectomy appear to allow early return to function. Acromioplasty or coracoacromial ligament release is generally not done in patients with RA because doing so could compromise the coracoacromial arch and may lead to anterosuperior instability, particularly in patients with rotator cuff dysfunction.

Cartilage-Sacrificing Procedures

When either nonsurgical management or cartilage-preserving procedures fail to provide adequate relief, prosthetic replacement is indicated for patients with unremitting or progressive pain and functional limitation. Approximately 20% to 35% of patients who require prosthetic replacement have concomitant rotator cuff tears; these may be addressed at the time of arthroplasty, necessitating a modification of the postoperative course. Rozing and Brand22 examined the results of rotator cuff repair at the time of shoulder arthroplasty for RA and concluded that concomitant cuff repair significantly (P = 0.002) improved postoperative clinical shoulder scores compared with patients in whom tears were not repaired.

The modular humeral components are available in a range of stem sizes and humeral heads. The varying stem sizes enable secure fixation both with and without cement. Cement fixation is more often used in rheumatoid patients because of the poor bone quality and proximal bone loss. Humeral heads are available in varying neck lengths and diameters, allowing improved soft-tissue balancing that enhances the stability of the implant. Asymmetric humeral heads are used to modify offset as well as to change the orientation of the component. These modifications are designed to improve soft-tissue balancing and the stability of the articulation. Familiarity with the components of the system allows the surgeon to optimize fixation, making a stable, functional articulation more likely.

A range of shoulder implant systems is available. Most use an allpolyethylene glenoid component; metal-backed components are no longer common. The glenoid component is designed for cement fixation, with a keel or multiple pegs for insertion into the glenoid.

Hemiarthroplasty

Indications for proximal humeral replacement (shoulder hemiarthroplasty) include extensive humeral head involvement with minimal or no involvement of the glenoid articular surface (uncommon in the rheumatoid shoulder); extensive humeral head and glenoid involvement with associated osteopenia and/or bone loss, such that secure fixation of the glenoid component is unattainable; and extensive articular cartilage deterioration in the presence of a massive, irreparable rotator cuff tear. In younger patients (<65 years) who wish to maintain an active lifestyle, concerns about glenoid component loosening have led some to avoid the use of glenoid components. However, long-term pain relief is less reliable than with glenoid resurfacing, and continued degeneration of the glenoid can result in progressive symptoms.23,24

The procedure is done with the patient in a beach-chair position, using an anterior deltopectoral approach. During the exposure, soft tissues are handled carefully as they may often be attenuated. The subscapularis tendon and underlying capsule are divided 1 cm medial to the insertion on the lesser tuberosity. There may be significant contracture of the anterior soft tissues requiring mobilization of the subscapularis tendon and the underlying capsule. This is generally done by releasing the adhesions of the subscapularis at the base of the coracoid and along the anterior glenoid neck. This should allow significant lateral excursion of the subscapularis tendon and muscle, which will enhance postoperative external rotation. In general, a circumferential capsular release around the glenoid margin, freeing the inferior and posterior capsules, will mobilize the rotator cuff, enhancing both intraoperative exposure and postoperative mobility.

After resection of the humeral head, the glenoid is carefully inspected to evaluate the integrity of the articular cartilage and the presence and degree of bone loss. Rarely is the articular cartilage of the glenoid sufficiently intact to obviate the need for resurfacing, particularly when significant humeral head changes are present. Therefore, isolateral humeral destruction is not the common indication for hemiarthroplasty in rheumatoid patients. More often, there is extensive glenoid bone loss, or the remaining bone is of insufficient quality to allow secure fixation of the glenoid component. When there is significant asymmetric glenoid wear, reaming of the glenoid should be considered to restore the concavity and thereby enhance the stability of the prosthetic glenoid articulation. The rotator cuff also should be carefully inspected: irreparable defects of the supraspinatus, infraspinatus, or teres minor tendons also preclude insertion of a glenoid component.

The proximal humeral osteotomy is performed to place the component in 25° to 40° of retroversion. Sequential reaming of the humeral shaft determines the appropriate component size. The decision to place a cemented or cementless humeral component generally is made intraoperatively. Cementless implantation is acceptable in most cases. However, in patients with extensive rheumatoid involvement of the proximal humerus with large cyst formation, cementing often is necessary to achieve rotational and axial stability. A modular implant is preferable because it provides an opportunity to adjust the soft-tissue balancing and enhance stability. Repair of the subscapularis tendon is critical. When the closure is complete, the amount of external rotation possible without undue tension on the subscapularis repair should be documented to guide the postoperative rehabilitation program.

Hemiarthroplasty results in reliable pain relief and improvement of function and range of motion, although the outcome is not as predictable in patients with RA as in patients with osteoarthritis.25 This is thought to be the result of poor bone stock and compromised soft tissues. Koorevaar et al26 examined the outcomes of 19 cases of shoulder hemiarthroplasty for RA at a mean of 8 years; 64% of patients reported little or no pain, and no patient complained of severe pain. Recurrence of symptoms and functional debilitation because of progressive glenoid degeneration may necessitate glenoid resurfacing, primarily in patients in whom the indication for hemiarthroplasty was a reasonably intact glenoid surface.

Total Shoulder Arthroplasty

Total shoulder arthroplasty is indicated for patients with debilitating pain and end-stage RA of the shoulder with extensive humeral head and glenoid articular cartilage loss, yet with sufficient bone stock and soft-tissue integrity to achieve a stable articulation. The initial exposure and preparation are the same as for the patient undergoing hemiarthroplasty. Exposure of the glenoid is obtained by subscapularis mobilization and capsular releases. With the glenoid exposed, the anterior glenoid neck is palpated to identify the direction for preparation of the glenoid component fixation. The glenoid is prepared using a combination of drills, reamers, and burrs. The reaming should provide an exacting congruency with the back surface of the glenoid component. Proper alignment of the reamer will correct asymmetric glenoid wear and allow restoration of more anatomic component orientation. Proper glenoid preparation is confirmed by insertion of a trial component. A dry field is obtained for optimal bone-cement interface, and the glenoid component is then cemented in place. The humeral head component is then inserted, as described. Appropriate soft-tissue balancing, which is essential for a stable articulation, is achieved by a combination of selective soft-tissue releases and insertion of appropriately sized prosthetic components (Fig. 7).

Figure 7
Figure 7:
Anteroposterior (A) and axillary (B) radiographs of the left shoulder in a 69-year-old woman with seropositive RA and debilitating pain for 1 year. T1-weighted coronal (C) and axial (D) magnetic resonance images of the same patient showing attenuation of the rotator cuff tendon (black arrow) but without a full-thickness tear. The humeral head erosions (asterisk) are extensive and well delineated. Glenoid bony architecture (white arrow) indicates that there is probably sufficient bone stock for placement of a glenoid component. Anteroposterior (E) and axillary (F) radiographs immediately after total shoulder arthroplasty.

Rotator cuff tears should be repaired at the time of total shoulder arthroplasty. The repair sequence varies, but generally the extent of the rotator cuff tear is identified with the initial exposure. The edges of the tear are tagged with sutures, and the rotator cuff is mobilized so that it can be advanced laterally to its insertion. After insertion of the glenoid component but before insertion of the humeral component, sutures are passed through drill holes in the greater tuberosity that will later be used for the tendon-to-bone repair. These sutures are left in place while the humeral component is inserted. When the components are in place and the humeral head is reduced, the rotator cuff repair is completed using the previously placed tendon-to-bone sutures. Any additional tendon-to-tendon sutures can be placed, as well. Performing the final portion of the rotator cuff repair after implantation of the components eliminates the stress on the repair that would occur if significant manipulation of the shoulder were necessary. Occasionally, additional surgical releases and rotator cuff mobilization are necessary to allow for secure repair to the greater tuberosity. The coracoacromial ligament usually is not released during hemiarthroplasty or total shoulder arthroplasty. When rotator cuff repair is necessary, the undersurface of the acromion should be inspected carefully, but acromioplasty is rarely necessary. The goal is to maintain the integrity of the coracoacromial arch because of its contribution to glenohumeral stability in these significantly compromised shoulders.

Several investigators have reported that total shoulder arthroplasty for end-stage RA results in short-and long-term pain relief, satisfactory increases in range of motion, and markedly improved functional status.27-29 Because of soft-tissue compromise and the inflammatory nature of the disease, the results of total shoulder arthroplasty in patients with RA have not been shown to be as satisfactory or reliable as those in patients with osteoarthritis. 25 Despite concerns about proximal humeral migration and glenoid radiolucent lines, long-term results have shown that the degree of pain relief, range of motion, abduction force, and functional status do not diminish significantly over time.30

Postoperative Rehabilitation

The postoperative rehabilitation regimen must be tailored to the specific needs of each patient. Design of the regimen is based on the surgeon's intraoperative assessment of the quality of the soft tissues, component stability, and any associated repairs. Patients should be counseled that maximum benefit after prosthetic shoulder replacement may not be realized until 6 months to 1 year after surgery.

Rehabilitation begins on the first postoperative day, with active range of motion for the ipsilateral hand, wrist, and elbow, and passive and active-assisted range of motion for the shoulder. Initially, this includes supine passive forward elevation and external rotation exercises with the arm at the side. The degree of external rotation allowed during the initial 6 postoperative weeks is determined by the intraoperative repair of the subscapularis tendon; in general, 30° to 40° of external rotation may be tolerated without placing undue tension on the repair. At approximately 4 to 6 weeks, a more active shoulder range of motion is initiated along with internal rotation behind the back. Isometric strengthening exercises are started 4 weeks after surgery, and resistive strengthening exercises usually are initiated 10 to 12 weeks postoperatively when active range of motion has progressed.

Complications

Adverse events have been reported in up to 11.0% of total shoulder arthroplasties and up to 15.7% of shoulder hemiarthroplasties31 (Table 3). Cofield et al31 categorized complications of shoulder arthroplasty into four groups: (1) coexisting injuries to the shoulder at the time of surgery, such as rotator cuff tear or chronic dislocation; (2) problems with the healing process after surgery, such as failure of subscapularis tendon healing resulting in anterior shoulder instability or weakness in internal rotation, or overexuberant postoperative fibrosis causing joint stiffness; (3) complications related to the general health of the patient, such as infection secondary to chronic immunosuppression; and (4) complications associated with joint arthroplasty, such as periprosthetic fracture or component loosening.

Table 3
Table 3:
Complications After Total Shoulder Arthroplasty and Shoulder Hemiarthroplasty

Significant instability after shoulder arthroplasty usually is recognizable by physical examination and radiography and can be related to improper soft-tissue balancing, rotator cuff disruption, component malposition, improper component sizing, or component loosening. Other factors associated with instability after prosthetic replacement of the shoulder include older age, chronic preoperative shoulder dislocation, and aberrant glenoid anatomy resulting from glenoid bone deficiency or asymmetric wear. Soft-tissue balancing intraoperatively should allow for up to 50% translation both anteriorly and posteriorly. Superior subluxation of the glenohumeral component is not necessarily indicative of rotator cuff disruption; inferior subluxation in the immediate postoperative period usually represents deltoid atony but can indicate inadequate soft-tissue tensioning, which may require secondary surgical corrections.

Axillary nerve neurapraxia is the most common injury. The musculocutaneous nerve may also be injured during exposure or overzealous retraction of the conjoined tendon. Radial nerve palsy also has been described secondary to cement extrusion from the canal distally, especially with revision arthroplasty or inadvertent humeral cortical penetration. If this finding is noted on postoperative radiographs, exploration is indicated. Continuity of the nerve should be confirmed and all cement removed. In most other cases of nerve injury, an initial period of observation is indicated because most nerve injuries represent neurapraxia. If neurologic improvement does not occur within 4 weeks, electromyography should be done to document the degree of neurologic injury and assess the potential for recovery. Exploration may be indicated for nerve palsies that do not improve by 12 weeks.

Periprosthetic fractures may occur intraoperatively or postoperatively. Intraoperative fractures can occur during humeral shaft preparation or insertion of the humeral component; postoperative fractures usually are a result of trauma. Fractures entirely distal to the humeral component may be treated nonsurgically with a fracture brace. Fractures proximal to the tip of the stem can be treated by cerclage wiring, plate fixation combined with cerclage wires, or, for intraoperative fractures, insertion of a long-stem component combined with cerclage wiring.

The risk of infection after prosthetic replacement is increased in the presence of diabetes mellitus, RA, lupus erythematosus, remote sites of infection, prior shoulder surgery, or use of immunosuppressive medications. Little has been published that specifically addresses the treatment of infected shoulder arthroplasty. For acute or subacute infection (<3 months after prosthetic replacement), open irrigation and débridement, followed by 6 to 8 weeks of intravenous antibiotics, is usually adequate. For delayed infection, component removal and insertion of antibiotic-impregnated cement is necessary. Staged reimplantation may be undertaken after the successful eradication of infection, as documented by normalization of the white blood cell count, sedimentation rate, C-reactive protein level, and intraoperative frozen section.

Prosthetic loosening almost always involves the glenoid component and is best minimized by careful glenoid preparation with preservation of bone stock, meticulous cement technique, and close attention to soft-tissue balancing. Massive, unreconstructable rotator cuff tears are a relative contraindication to glenoid replacement. These tears underscore the importance of the rotator cuff in maintaining joint position and preventing excessive, eccentric glenoid loading that can increase the risk of early loosening. Clinically significant glenoid loosening is uncommon compared with radiographic findings suggestive of loosening. Accordingly, it is important to exclude other causes of shoulder pain, such as occult infection or rotator cuff tear. If glenoid revision is done, removal of the loose component may reveal a large central glenoid defect that may not be structurally amenable to component reinsertion, even after bone grafting. In such cases, impaction grafting may be done with contouring of the remaining glenoid bone to a slight concavity for pseudocongruence with the humeral head component.

Arthrodesis

Although arthrodesis of the glenohumeral joint has been described for end-stage RA,32 advances in prosthetic replacement and surgical technique have largely supplanted arthrodesis as the predominant primary treatment of the end-stage rheumatoid shoulder. Arthrodesis of the rheumatoid shoulder should be undertaken only for selected indications. These indications include failed total shoulder arthroplasty or end-stage involvement with a recent history of joint sepsis. In these situations, patients may benefit from glenohumeral fusion in 30° of abduction, 30° of forward flexion, and 30° of internal rotation to allow for handto-mouth and hygiene activities. Arthrodesis can be done using a variety of techniques, including screw fixation or plate-and-screw fixation. Although plate-and-screw fixation offers the potential avoidance of postoperative spica immobilization, the bone quality in rheumatoid patients may limit the security of the fixation, and additional external (spica) immobilization still will be needed postoperatively. The utility of shoulder arthrodesis must be evaluated in the context of ipsilateral and contralateral upper extremity involvement.

Acromioclavicular Involvement

Rheumatoid involvement of the acromioclavicular joint is common, affecting up to 63% of rheumatoid patients with painful shoulders.33 It is often adequately addressed nonsurgically with medications and corticosteroid injection. However, persistent or progressively debilitating pain secondary to extensive, symptomatic erosions may necessitate distal clavicular resection with synovectomy, typically with successful results.7 Petersson33 reported acromioclavicular joint resection and subacromial bursectomy to be an effective procedure at follow-up of 18 to 62 months. Either open or arthroscopic resection of the distal clavicle may be done. In the setting of RA, however, resection rarely is performed as an isolated procedure; more often, it is done at the time of prosthetic replacement.

Sternoclavicular Involvement

The reported incidence of rheumatoid involvement of the sternoclavicular joint ranges from 1% to 41%.34 Symptomatology typically is overshadowed by glenohumeral involvement and usually responds to nonsurgical intervention and intra-articular injections. Recalcitrant symptoms lasting more than 6 to 12 months may be addressed with sternoclavicular joint débridement and medial clavicle resection.34 Care must be taken to preserve the stabilizing ligaments to avoid complications associated with sternoclavicular instability.

Summary

Care of the patient with RA of the shoulder requires a multidisciplinary approach involving the primary care provider, rheumatologist, orthopaedic surgeon, and physical/ occupational therapists. Early rheumatoid involvement of the shoulder with minimal articular destruction and functional limitations may be managed nonsurgically with medications and physical therapy. Advanced rheumatoid disease of the shoulder with significant pain and articular destruction may necessitate surgical intervention, ranging from synovectomy to total shoulder arthroplasty. Although the results of prosthetic shoulder replacement for end-stage RA are not comparable to those achieved for osteoarthritis, symptomatic improvement often is dramatic, with satisfactory relief of pain, improved range of motion, and increased functional ability.

References

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2. Petersson CJ: Painful shoulders in patients with rheumatoid arthritis: Prevalence, clinical and radiological features. Scand J Rheumatol 1986;15:275-279.
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