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A 63-year-old, right-hand-dominant male presents to your office with right shoulder pain that has pro- gressively worsened over the past several years. The pain is worse with activity and bothers him at night. He denies any previous history of trauma or surgical procedures. On examination, he is noted to have limited active and passive ROM, particularly in external rotation. He has significant crepitus and pain with ROM. Strength testing reveals an intact rotator cuff. X-rays are shown in Figure 45-1.

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Figure 45-1. (A-C) X-rays showing glenohumeral osteoarthritis.

Vignette 45: Answer

The diagnosis in this case is primary shoulder OA. The patient demonstrates classic symptoms of OA, which is confirmed on exam and with imaging. He has no history of trauma, instability, or prior surgery that could cause secondary OA. History should also be obtained about any rheumatologic or systemic disorders that may suggest inflammatory arthritides. In OA, pain and crepitus on examination are characteristic. Due to posterior osteophytes, the anterior capsule can become contracted, leading to a significant decrease in external rotation.149 _{The rotator cuff is typically preserved in patients with OA; only 5% to 10% have cuff}

tears.149

X-rays are diagnostic for OA and show joint space narrowing, subchondral sclerosis, and osteophyte for- mation. In OA, axillary views can demonstrate posterior humeral head subluxation and glenoid wear. This posterior subluxation can cause a false appearance of superior head subluxation on the AP image. Walch et al described the glenoid morphology in OA, classifying it into 3 types: concentric wear with no subluxation (type A), biconcave glenoid with posterior wear and subluxation (type B), and retroverted glenoid with posterior subluxation (type C).150 _{In patients with RA, x-rays first reveal osteopenia, followed by erosions}

of the inferior humeral head and glenoid.151 _{These erosions can progress and lead to significant medializa-}

tion of the humeral head. If glenoid bone loss is ever a concern, then a CT scan is indicated for preoperative planning. MRI is used only if there is a concern about the rotator cuff. In patients for whom inflammatory arthritis is suspected, laboratory tests, including ESR, CRP, CBC, and rheumatologic laboratory tests, should be sent. An arthrocentesis with crystal analysis can also be performed to evaluate for gout or pseudogout.

Initial treatment options of shoulder arthritis are nonoperative. They include intra-articular corticoste- roid injections, NSAIDs, and physical therapy. Surgery is indicated for patients who fail nonoperative thera- py and continue to have significant pain and impairment in function. Arthroscopic debridement is contro- versial and is not routinely indicated, although it may be applicable in young patients. Hemiarthroplasty can be used in the setting of large rotator cuff tears or if insufficient glenoid bone stock exists to place a glenoid component (ie, RA with severe medialization). A concentric glenoid is key to success of hemiarthroplasty.149

Total shoulder arthroplasty (TSA) is also a good option for the treatment of severe glenohumeral arthritis in patients who have an intact rotator cuff (Figure 45-2). Pain relief and ROM are typically significantly improved. A cemented polyethylene glenoid is the gold standard.149 _{In patients with total shoulder arthro-}

plasty and rotator cuff deficiency, glenoid loosening can occur from repetitive micro motion. However, a meta-analysis by Bryant et al of patients with OA revealed that TSA provided better functional outcome and ROM at short-term follow-up.152

Patients with chronic massive rotator cuff tears can develop rotator cuff arthropathy. This form of shoul- der arthritis typically affects the dominant hand and tends to have a female predominance. Examination will reveal muscle atrophy, pain with ROM, rotator cuff weakness, and possible anterosuperior escape of the humeral head with associated anterior prominence. Painful pseudoparalysis can be present at endstage rotator cuff arthropathy. The integrity of the deltoid should also be closely evaluated to help determine treatment options. X-rays can demonstrate superior migration of the humeral head, with bony changes termed femoralization of the head, and acetabularization of the acromion.153 _{Peripheral osteophytes are less}

common. Nonoperative treatment is similar to OA. In patients for whom this fails and who demonstrate

Figure 45-2. (A) AP, (B) scapular Y, and (C) axillary lateral x-rays of the left shoulder after TSA.

a functioning deltoid, then surgical intervention can be considered. Pseudoparalysis is an indication for surgery. The coracoacromial arch functions as the limit to superior migration of the humeral head in these patients and, consequently, must be carefully preserved during all procedures.153 _{Treatment options include}

hemiarthroplasty or reverse TSA. Hemiarthroplasty provides pain relief but limited function. Reverse TSA places the center of rotation (COR) of the implant on the neck of the scapula (medial and distal), increasing the lever arm of the deltoid. For this reason, reverse TSA has the potential to improve pain and function. Good glenoid bone stock is required, and indications are typically limited to elderly patients. TSA is not indicated due to early glenoid failure.

Why Might This Be Tested? Differing forms of glenohumeral arthritis can present with different radio-

graphic findings and different treatment principles. Glenoid erosion can change surgical planning and is a potential test topic. Some interventions are contraindicated in certain conditions, such as TSA in cuff arthropathy, or reverse TSA in the setting of deltoid dysfunction. Know the pathogenesis of OA, RA, and cuff arthropathy and the indications for intervention in each.

Establish the diagnosis of glenohumeral arthritis and determine which interventions are indicated. Shoulder OA with concentric glenoid = hemiarthroplasty; rotator cuff deficien- cy = reverse TSA; in between = standard TSA.