It is important to understand the type of arthritis that afflicts the shoulder in that each type has its own special features and treatment concerns. Here is a straightforward way to group the different types of shoulder arthritis. The most common types of arthritis are different for older and younger patients (Saltzman JBJS 2010). Click on the diagnosis to see the typical radiographic appearance.
I. Primary osteoarthritis (primary degenerative joint disease) – non-inflammatory arthritis without prior injury or surgery. This is the commonest type of arthritis in the U.S., but less common in Europe. It is characterized by dense bone, substantial osteophytes, and (especially in males) with posterior glenoid erosion and posterior displacement of the head on the glenoid.
II. Secondary osteoarthritis
A. Post-traumatic arthritis – arthritis after prior injury. The management of this type of arthritis may be complicated by bone deformity, the presence of hardware, rotator cuff deficiency, deltoid injury, infection and nerve deficits.
B. Capsulorrhaphy arthropathy – arthritis after prior repair for glenohumeral instability. These shoulders often have excessive tightness of external rotation with posterior glenoid erosion and posterior displacement of the head on the glenoid. They seem to be at higher risk for nerve injury and infection
C. Chondrolysis – arthritis after intra-articular infusion of local anesthetics with a pain pump. These shoulders are often found in very young individuals for whom no type of joint replacement is very satisfactory. These shoulders are often very stiff and painful, even after a technically well done arthroplasty.
D. Inflammatory arthritis – rheumatoid arthritis, lupus, other auto-immune forms of arthritis, septic (infectious) arthritis. These shoulders have soft, fragile bone, fragile soft tissues, and few osteophytes with medial glenoid erosion.
E. Avascular necrosis – collapse of the humeral articular surface from ischemia of the subchondral bone. If treated before substantial humeral head collapse, these shoulders may have abnormalities only on the humeral side, so that a humeral hemiarthroplasty may suffice.
F. Dysplasia – developmental defect, usually resulting in deficient posterior inferior glenoid. In these shoulders the posterior aspect of the glenoid is underdeveloped resulting in severe retroversion of the glenoid surface and posterior instability of the shoulder. It is difficult to satisfactorily place a glenoid component in these shoulders.
G. Rotator cuff tear arthropathy – a destructive condition destroying both the articular cartilage of the glenohumeral joint and the integrity of the rotator cuff tendons. These shoulders have the double problem of arthritis and a lack of sufficient rotator cuff to stabilize the shoulder. Often a special prosthesis, such as a CTA prosthesis or a reverse total shoulder may be needed.
**See the Shoulder Arthritis Book, click here.**