Christian J. H. Veillette and Scott P. Steinmann
DEFINITION
Osteoarthritis (OA) is a degenerative disorder of synovial joints characterized by focal defects in articular cartilage with reactive involvement in subchondral and marginal bone, synovium, and para-articular structures.1,10
Patients with degenerative joint disease (DJD) of the shoulder often have coexisting pathology, including bursitis, synovitis, loose bodies, labral tears, osteophytes, and articular cartilage defects.2,3,9
Arthroscopic débridement may be a reasonable treatment option in these patients after conservative methods have been unsuccessful and when joint replacement is not desired.
Historically, patients who have early OA in whom concentric glenohumeral articulation remains with a visible joint space on the axillary radiograph are candidates for arthroscopic débridement.14
Patients with severe glenohumeral arthritis for whom shoulder arthroplasty is not ideal, such as young or middle-aged patients and older patients who subject their shoulders to high loads or impact, remain an unresolved clinical problem and are potential candidates for arthroscopic techniques.
There are four basic options for arthroscopic treatment in a patient with DJD of the shoulder:
Glenohumeral joint débridement
Capsular release
Subacromial decompression
Glenoidplasty
Choosing which of these four options to perform on a shoulder with DJD depends on the degree of arthritis and the skill, philosophy, and experience of the surgeon.
The goal of arthroscopic débridement is to provide a period of symptomatic relief rather than reverse or halt the progression of OA.
ANATOMY
The normal head shaft angle is about 130 degrees, with 30 degrees of retroversion.
The articular surface area of the humeral head is larger than that of the glenoid, allowing for large normal range of motion.
Glenoid version, the angle formed between the center of the glenoid and the scapular body, averages 3 degrees and is critical for stability.
The glenoid fossa provides a shallow socket in which the humeral head articulates. It is composed of the bony glenoid and the glenoid labrum.
The labrum is a fibrocartilaginous structure surrounding the periphery of the glenoid. The labrum provides a 50% increase in the depth of the concavity and greatly increases the stability of the glenohumeral joint.
The glenoid had an average depth of 9 mm in the superoinferior direction and 5 mm in the anteroposterior direction with an intact labrum.6,8
Capsuloligamentous structures provide the primary stabilization for the shoulder joint (FIG 1).
Within this capsule are three distinct thickenings that constitute the superior glenohumeral ligament, middle glenohumeral ligament, and inferior glenohumeral ligament.
PATHOGENESIS
OA may be classified as primary, when there is no obvious underlying cause, or secondary, when it is preceded by a predisposing disorder.
Pathology in patients with glenohumeral OA includes a degenerative labrum, loose bodies, osteophytes, and articular cartilage defects in addition to synovitis and soft tissue contractures.
The disease process in OA of the shoulder parallels that of other joints. Degenerative alterations primarily begin in the articular cartilage as a result of either excessive loading of a healthy joint or relatively normal loading of a previously disturbed joint.12
Progressive asymmetric narrowing of the joint space and fibrillation of the articular cartilage occur with increased cartilage degradation and decreased proteoglycan and collagen synthesis.
Subchondral sclerosis develops at areas of increased pressure as stresses exceed the yield strength of the bone and the subchondral bone responds with vascular invasion and increased cellularity.
FIG 1 • Glenoid anatomy. The glenoid has an average depth of 9 mm in the superoinferior direction and 5 mm in the AP direction with an intact labrum.
Cystic degeneration occurs owing to either osseous necrosis secondary to chronic impaction or the intrusion of synovial fluid.
Osteophyte formation occurs at the articular margin in nonpressure areas by vascularization of subchondral marrow, osseous metaplasia of synovial connective tissue, and ossifying cartilaginous protrusions.
Fragmentation of these osteophytes or of the articular cartilage itself results in intra-articular loose bodies. In late stages, complete loss of articular cartilage occurs, with subsequent bony erosion.
Posterior glenoid erosion is predominant, leading to increased retroversion of the glenoid and predisposing to subluxation and reduction of the humeral head, causing symptoms of instability.
NATURAL HISTORY
Information on the natural history of OA in individuals and its reparative processes is limited.
Progression of OA is considered generally to be slow (10 to 20 years), with rates varying among joint sites.10
No specific longitudinal studies exist on the progression of shoulder OA.
PATIENT HISTORY AND PHYSICAL FINDINGS
Typical history for patients with OA is progressive pain with activity over time.
In early stages, pain is related to strenuous or exertional activities but over time it progresses to activities of daily living. In later stages, pain occurs at rest and at night.
Pain may be mistaken for impingement syndrome early in the disease process or rotator cuff disease when symptoms occur in the presence of good motion.
Progression of the disease often leads to secondary capsular and muscular contractures with loss of active and passive motion.
Mechanical symptoms such as catching and grinding are often reported with use of the shoulder.
The pain of shoulder OA can be divided into three types:
Pain at extremes of motion: due to osteophytes and stretching of the inflamed capsule and synovium
Pain at rest: due to synovitis (pain at night is not the same as pain at rest and may be due to awkward positions or increased pressure)
Pain in the mid-arc of motion: usually associated with crepitus and represents articular surface damage
Physical examination should include the following:
Range of motion: Loss of both active and passive motion consistent with soft tissue contractures. In patients with preserved passive motion but loss of active motion, rotatory cuff pathology should be ruled out.
Compression–rotation test: Pain during mid-arc of motion is a potentially poor prognostic indication.
Neer test and Hawkins test: Often patients with OA have positive impingement signs related to articular lesions in the glenohumeral joint or to the synovitis in the joint and subacromial pathology.
Supraspinatus evaluation: Weakness may reflect associated supraspinatus tear. Patients with OA may have weakness related to pain inhibition on resistance.
Infraspinatus and teres minor evaluation: Weakness may reflect associated posterior rotator cuff tear. Patients with OA may have weakness related to pain inhibition on resistance.
Subscapularis evaluation: Weakness may reflect associated subscapularis tear. Patients with OA may have weakness related to pain inhibition on resistance.
IMAGING AND OTHER DIAGNOSTIC STUDIES
A standard shoulder series consisting of a true anteroposterior view in the scapular plane, a scapular lateral view, and an axillary view should be obtained on all patients before surgical intervention (FIG 2A,B).
Classic findings of glenohumeral OA are joint space narrowing, subchondral sclerosis, subchondral cysts, and osteophyte formation.
Posterior wear of the glenoid is often noted on the axillary view in later stages of the disease.
Magnetic resonance imaging (MRI) is more sensitive for the diagnosis of early-stage OA than are plain radiographs and can identify concurrent soft tissue pathology.
Up to 45% of patients with grade IV chondral lesions can have no radiographic (MRI or plain radiograph) evidence of OA on preoperative imaging.2,13
Computed tomography (CT) scanning provides improved visualization of the bony glenoid, osteophytes, and loose bodies (FIG 2C).
Three-dimensional reconstructions provide an excellent visual representation of the biconcave glenoid to assist in preoperative planning (FIG 2D).
DIFFERENTIAL DIAGNOSIS
Impingement syndrome
Adhesive capsulitis
Superior labral anterior to posterior (SLAP) lesions
Rotator cuff tears
Instability
NONOPERATIVE MANAGEMENT
Standard nonoperative modalities, such as nonsteroidal antiinflammatory medications, steroid injections, and physical therapy, should be explored before arthroscopic techniques.
SURGICAL MANAGEMENT
Current indications for arthroscopic osteocapsular arthroplasty and glenoidplasty are patients with the following:
Moderate to severe glenohumeral OA
A biconcave glenoid
Moderate to severe pain causing functional impairment that has failed to respond to nonsurgical treatment
Painless crepitus with glenohumeral motion during joint compression
Patient must have a relative contraindication to total shoulder arthroplasty such as age younger than 50 years, excessive physical demands, or unwillingness to consider shoulder replacement.
Age and prior successful total shoulder arthroplasty on the contralateral shoulder are not contraindications.
FIG 2 • A. AP radiograph shows loss of joint space, subchondral sclerosis, and hypertrophic changes with early inferior osteophyte formation. B. Axillary lateral radiograph reveals complete loss of joint space with typical posterior glenoid wear and static posterior subluxation of the humeral head. C. Twodimensional computed tomography scan shows loss of articular cartilage, subchondral sclerosis, osteophytes, and posterior glenoid erosion with static posterior subluxation of humeral head. D. Three-dimensional reconstruction view shows biconcave glenoid with humerus subtracted from view as would be anticipated from an anterosuperior arthroscopic portal. These views allow the glenoid and humerus to be rotated to understand exact location of pathology to be seen from different arthroscopic working portals.
Glenoidplasty is performed if there is a biconcave glenoid from posterior wear and involves recontouring the surface to recreate a single concavity.
The rationale is to restore the position of the humeral head, thus reducing posterior subluxation, increasing the surface area of articulation, decreasing joint pressure, and relaxing the anterior soft tissues.
Subacromial decompression preoperative examination and intraoperative arthroscopic findings implicate the subacromial space as source of pain.
A thickened bursa consistent with chronic bursitis has been documented, and several authors advocate a soft tissue decompression, at a minimum.3,15
Bleeding from the undersurface of the acromion may lead to subacromial fibrosis and loss of motion. Therefore, routine subacromial decompression is not recommended.
Preoperative Planning
The surgeon should review high-quality radiographs, especially the axillary view if glenoidplasty will be performed, to plan the increase in depth of the glenoid required to convert the biconcave glenoid back to a single concavity.
The surgeon examines the range of motion under anesthesia and compares it to the opposite side.
Positioning
The patient is placed in the beach-chair or lateral decubitus position after regional anesthesia (interscalene block) or general anesthesia is obtained.
Unobstructed access to the anterior and posterior aspects of the shoulder is imperative (FIG 3).
A potential disadvantage of the lateral decubitus position is the need to take the arm out of traction periodically to check the range of motion after capsular resection.
If working in the area of the axillary nerve, the semi-abducted position used in the lateral decubitus position tends to bring the axillary nerve closer to the capsule.
Approach
A standard midposterior arthroscopic portal is established in usual fashion.
A standard anterior portal is made using an 18-gauge spinal needle under direct arthroscopic vision to locate the position in the rotator interval.
Additional portals that are often required include a midlevel anterior portal (adjacent to the superior border of the subscapularis) for osteophyte removal and a posteromedial portal for placement of a retractor to clear the axillary pouch from the humeral head and neck.
It is helpful to place both the posterior and anterior portals a bit more inferior than usual to allow easier access to the inferior aspect of the joint.
FIG 3 • Patient placed in the lateral decubitus position.
TECHNIQUES
DIAGNOSTIC ARTHROSCOPY
A standard 15-point assessment of the arthroscopic glenohumeral anatomy as outlined by Snyder11 is performed.
Typical findings include extensive synovitis, especially on the undersurface of the rotator cuff, fraying of the labrum, and fibrillation or loss of articular cartilage.
SYNOVECTOMY AND DÉBRIDEMENT
A complete systematic synovectomy is performed using a combination of an arthroscopic thermal device to minimize bleeding and a full-radius shaver (4.8 or 5.5 mm).
The surgeon begins by removing synovium from the anterosuperior aspect of the joint, moving posteriorly and then inferiorly into the axillary recess and finally the posterior inferior synovium.
A full-radius shaver is used to débride the fraying labrum and remove loose bodies and unstable chondral flaps.
INFERIOR OSTEOPHYTE EXCISION
The surgeon removes impinging osteophytes, especially any inferior osteophyte from the humeral head, and performs appropriate capsular or interval releases to regain passive motion.
An efficient way to visualize and remove inferior osteophytes is to view from the anterior portal using a standard 30-degree arthroscope and then establish a posterior inferior working portal. The shaver or burr can then be brought in posteriorly to remove capsule or osteophytes.
The inferior humeral osteophyte is removed first through the posterior inferior working portal using a 4.0-mm hooded burr (which protects the inferior capsule and the axillary nerve) beginning posteriorly and moving anteriorly.
The humerus can be internally rotated to deliver the osteophyte and improve positioning of the instrument.
CAPSULECTOMY AND RELEASE
The inferior capsular attachment to the humeral head should be identified and used as a landmark to recreate the normal architecture of the humerus.
A 5.5-mm full-radius shaver is useful to débride any loose bony fragments and soft tissues from the burr.
Suction on the instruments should be avoided to decrease the likelihood of unintentional damage to the axillary nerve from soft tissue drawn into the instrument.
A curved curette may be required to reach around and remove the anterior aspect of the inferior osteophyte.
Fine contouring may be done with the shaver or hand rasps as necessary.
Working space in the inferior axillary pouch is markedly increased after removal of the inferior osteophyte and permits improved visibility of the inferior capsule and safer performance of partial capsulectomy.
A full-radius shaver is placed through the posterior portal and used to create a capsulotomy in the posterior aspect of the inferior capsule (in the right shoulder at the 7 o'clock position) adjacent to the glenoid rim.
The plane between the inferior capsule and underlying soft tissues is then developed with a wide duck-billed basket punch moving from a posterior to an anterior direction. The shaver is then used to widen the resection.
The capsulectomy should be performed as close to the glenoid rim as possible to minimize the risk to the axillary nerve, which should be identified and protected with a probe after the 6 o'clock position is reached.
A partial capsulectomy is then performed anteriorly, anterior osteophytes are removed, and the capsule is removed from the rotator interval (TECH FIG 1).
TECH FIG 1 • Osteocapsular arthroplasty. Osteophyte removal is usually best done before resection of the capsule and primarily involves working in the inferior aspect of the glenohumeral joint. A. Inferior osteophytes are best viewed from the anterior portal using a standard 30-degree arthroscope, and then the shaver or burr can be brought in from a posterior inferior working portal to remove capsule or osteophytes. B. Anterior capsulectomy is done viewing from a posterior portal and using an anterior portal to direct a cautery–radiofrequency device or a shaver to release the anterior capsule from the anterior glenoid surface. C. Inferior capsulectomy is performed viewing from the anterior portal, and a duck-billed resector is brought into the joint from posterior to remove the inferior capsule.
This can be done viewing from a posterior portal and using an anterior portal to direct a cautery–radiofrequency device or a shaver to release the anterior capsule from the anterior glenoid surface.
Any residual anteroinferior capsule can be resected from the anterior portal to connect with the inferior capsulectomy.
The direct posterior capsule is not generally removed, just as it is not typically resected during a total shoulder replacement. The posterior capsule is often lax from the posterior subluxation and posterior glenoid wear seen in osteoarthritis.
GLENOIDPLASTY
Anterior and posterior portals are used to perform the procedure, and the biconcave shape of the glenoid can best be visualized by looking inferiorly from the anterior portal (TECH FIG 2A).
A full-radius shaver is used to remove the remaining cartilage from the anterior glenoid facet (TECH FIG 2B).
The central vertical bony ridge is then removed using a 4-mm round burr moving from anterior to posterior in a superior to inferior direction.
The glenoid is divided into quarters and the superior half is contoured first to allow comparison with the prior biconcave glenoid (TECH FIG 2C).
The view of the glenoid can be alternated from front to back, and once a single concave surface has been established, a large hemispherical hand rasp can be used to deepen and smooth the surface (TECH FIG 2D).
The glenoidplasty is assessed intraoperatively by performing a compression–rotation test and palpating for crepitus and assessing the rotation of the humerus on the new glenoid surface arthroscopically.
TECH FIG 2 • Arthroscopic images of glenoid with posterior erosion prior to glenoidplasty (A) and after removal of anterior cartilage from glenoid (B). A bony central ridge separates the anterior and posterior aspects of the glenoid. C,D. Glenoidplasty is performed with an anterior and a posterior portal. C. With the surgeon alternating viewing from the front and the back, the remaining cartilage is first removed from the anterior glenoid facet and then the central vertical bony ridge is resected. A round 4-mm burr is usually sufficient to accomplish this task. D. Once a single concave surface is established, a large rasp can be used to smooth the surface.
SUBACROMIAL DECOMPRESSION
Using standard portals to explore the subacromial space, a shaver or cautery–radiofrequency probe is placed above the rotator cuff, and any thickened bursa is removed.
Bursal-sided fraying or tearing of the rotator cuff can also be addressed at the same time.
There is usually no need to perform an acromioplasty, but if a minor spur of the acromion is encountered it can be resected. The corocoacromial ligament should be preserved.
POSTOPERATIVE CARE
Full, unrestricted passive and active assisted range of motion is initiated on the first postoperative day.
Patients with an osteocapsular arthroplasty and glenoidplasty have an indwelling glenohumeral catheter for postoperative analgesia and stay in the hospital overnight.
Most patients benefit from a structured therapy program supervised by a trained therapist to encourage full passive and active motion.
The patient begins isometric strengthening immediately and progresses to isotonic exercises as tolerated.
Patients should be allowed to go back to work as soon as they are comfortable.
OUTCOMES
Ellman et al3 showed the benefit of arthroscopic débridement of the glenohumeral joint in 18 patients who underwent initial shoulder arthroscopy for impingement syndrome but were shown at operation to have coexisting glenohumeral DJD that was not evident on preoperative clinical and radiographic evaluation.
Weinstein et al14 reported an 80% satisfactory improvement in 25 patients with early OA treated with arthroscopic débridement.
Cameron et al2 reported on 61 patients with grade IV chondral lesions of the shoulder treated with arthroscopic débridement with or without capsular release. Overall, 88% of patients had a satisfactory outcome.
Pain relief is not related to the radiographic stage of arthritis or the location of the lesion. However, return of pain and failure are associated with osteochondral lesions greater than 2 cm in diameter.2
Kelly et al7 presented the results on 14 patients with a mean age of 50 years treated with osteocapsular arthroplasty and glenoidplasty. Early follow-up at 3 years showed an 86% rate of improvement, and 92% agreed that the surgery was worthwhile. No complications were reported and there was no evidence of medial migration of the humerus.
COMPLICATIONS
None of the previously published studies on arthroscopic treatment of glenohumeral OA reported complications.
Ogilvie-Harris and Wiley9 reported 15 complications in 439 patients (3%) treated with arthroscopic surgery of the shoulder.
Medial migration of the humerus after glenoidplasty and inability to perform glenoid resurfacing during total shoulder replacement has not been encountered.
REFERENCES
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15. Witwity T, Uhlmann R, Nagy MH, et al. Shoulder rheumatoid arthritis associated with chondromatosis, treated by arthroscopy. Arthroscopy 1991;7:233.