CHAPTER 28 Glenohumeral Arthritis
Initially, arthroscopic management of shoulder arthritis was limited to diagnosis. The pioneering work of Ellman and colleagues1 and Cofield2 was primarily directed at differentiating arthritis from other shoulder diagnoses, especially in its early stages, where it is often radiographically silent. Treatment of these serendipitously identified lesions was limited to lavage and débridement, with little information as to functional outcomes. The outcome of arthroplasty, especially in younger individuals, has also been better defined. Although showing improvement, Sperling and associates3 have shown that half of all patients who have an arthroplasty for shoulder arthritis who are younger than 50 years have an unsatisfactory outcome, whether or not the glenoid is resurfaced. The poor outcomes and limited durability of arthroplasty in young individuals has led to renewed interest in nonarthroplasty treatment methods for glenohumeral arthritis, especially those techniques that can be performed arthroscopically. Arthroscopic débridement for arthritis now has reasonable midrange results reported, with significant information to relate to the prospective patient in regard to anticipated outcome. Although other techniques have also been reported, follow-up and detailed information about outcomes remain limited.
Arthritis of the shoulder has traditionally been classified into inflammatory or noninflammatory arthropathies (Table 28-1). Each diagnosis will have its unique presentations and difficulties. The primary unifying factor is the presence or absence of significant synovitis with the inflammatory arthropathies for which arthroscopic synovectomy is recommended. Recent peer-reviewed studies have shown significant benefit for synovectomy and arthroscopic treatment in patients with rheumatoid arthritis, although progression of disease is not universally halted, and maximal benefits were seen in patients with more modest radiographic changes.4 Conversely, synovectomy would rarely be indicated in noninflammatory arthropathy.
|Rheumatoid arthritis||Primary osteoarthritis|
|Systemic lupus erythematosus||Posttraumatic osteoarthritis|
|Calcium pyrophosphate deposition||Postinstability arthritis|
|Psoriatic arthritis||Capsulorrhaphy arthropathy|
|Ankylosing spondylitis||Charcot arthritis|
Gout is uncommon in the shoulder, and rarely requires arthroscopic treatment. Both ankylosing spondylitis and psoriatic arthritis share a common presentation of concomitant acromioclavicular arthritis, with the requirement for partial distal claviculectomy at surgery. Calcium pyrophosphate deposition is a common finding in degenerative arthritis; its significance in terms of altering treatment for the patient who fails conservative management for their arthritis is unclear.
Noninflammatory arthritis rarely presents with significant synovitis. Arthroscopic treatment for these conditions will vary depending on the associated findings and preference of the surgeon. The Outerbridge classification,5 developed for the knee, has been widely used to classify the extent of arthritic change in the shoulder (Table 28-2). Recent data have shown that the Outerbridge classification is of significant benefit in predicting the outcome of arthroscopic treatment of the shoulder. Radiographic classification is also of value. Although many classifications are available, that of Samilson and Prieto6 has been widely used to assess the outcome of arthroscopic treatment of the arthritic shoulder (Table 28-3). Chondrolysis has been a challenging problem that has been associated with thermal capsulorrhaphy and pain pumps with continuous infusion of local anesthetics. The cause of chondrolysis in general remains unclear; degeneration, inflammation or infection may play a role.7
|I||Softening or blistering|
|II||Fissuring or fibrillation|
|II||Mild arthrosis, osteophyte <3 mm|
|III||Moderate arthrosis, osteophyte 3- 7 mm, some joint space irregularity|
|IV||Severe arthrosis, osteophyte >7 mm, joint space narrowing, sclerosis|
From Samilson RL, Prieto V. Dislocation arthropathy of the shoulder. J Bone Joint Surg Am. 1983;65:456-460.
ANATOMY AND PATHOANATOMY
Anatomic considerations are those for shoulder arthroscopy in general. The thickness of articular cartilage is variable in the shoulder. There is a normal bare area on the posterior humerus that can involve as much as 20% of the humeral surface. The glenoid similarly has a bare area similar to the fovea in the hip. The glenoid bare area can be used as a landmark for the anatomic center of the glenoid. Capsular contractures can be responsible for restriction of motion and increased shear forces across the articular cartilage. Glenohumeral osteoarthritis classically presents with anterior capsular contracture causing loss of external rotation and posterior subluxation. With time, posterior glenoid erosion can occur, causing a biconcave glenoid. Issues arise in regard to successful joint entry and movement of instruments, and can present challenges requiring meticulous attention to detail in regard to establishing portals and avoiding instrument breakage.
Findings for arthritis, especially in the early stages, can often be vague and nonspecific, as initially noted by Ellman and coworkers.1 Arthroscopy and synovial biopsy remain principal mechanisms of diagnosis for early arthritis of the inflammatory or degenerative type. Nonspecific deep tenderness, especially posteriorly, can be a clue. Pain at the extremes of motion may be present. The hallmark of later degenerative glenohumeral osteoarthritis is progressive loss of active and passive external rotation of motion. Crepitus is nonspecific, but can be present in inflammatory and noninflammatory arthritis. Warmth, redness, and swelling are nonspecific findings. Often, differential injections can be very useful. Patients with early glenohumeral arthritis will have a negative subacromial lidocaine impingement test but a positive response to intra-articular lidocaine injection.
Changes of early arthritis are often difficult to detect on plain radiographs, as reported early on by Ellman and colleagues.1 Later osteoarthritic changes such as joint space narrowing, posterior subluxation, and the common anteroinferior osteophyte described by many as the goat’s beard osteophyte. Inflammatory arthritis will rarely present with significant osteophytes. Periarticular erosions, however, are common, resulting from chronic synovitis, and vertical migration caused by associated rotator cuff damage can be seen. MRI scanning similarly can be negative in early disease, and standard MRI scanning with or without contrast will often miss significant articular cartilage injuries. The presence of a large effusion on an MRI scan can indicate an active arthritic process, especially if other obvious causes for the effusion are absent. Investigational MRI techniques may improve the accuracy of MRI for articular cartilage injuries.
Nonoperative treatment remains the mainstay of the management of the arthritic shoulder. Because all treatment would require permanent activity modification in the postoperative period, preoperative activity modification would seem to be in order. Heavy weightlifting, impact activities, and manual labor would at best be expected to eliminate the long-term benefit of any operative treatment, and honest counseling about reasonable activities with the arthritic shoulder is necessary. Anti-inflammatory medications can offer symptomatic relief. Gentle physiotherapy can bring significant improvement in range of motion. Steroid injection can also be of benefit in inflammatory and noninflammatory conditions. Viscosupplementation is not currently approved for the shoulder by the U.S. Food and Drug Administration (FDA) but has shown benefits in the knee, and might offer similar short-term benefits in the shoulder.8 Operative treatment should only be considered for those individuals who have failed nonoperative treatment.