Osteoarthritis Of The
Glenohumeral Joint
Osteoarthritis of the
shoulder is considered a degenerative condition of the articular cartilage. It
may be associated with inflammatory changes of the joint, but the damage to the
cartilage is not primarily based on an inflammatory pathologic process as it is
for rheumatoid arthritis. The rotator cuff tendons are almost always intact in
patients with osteoarthritis, and there is a proliferative osteophyte formation
around the periphery of the humeral head, making it much larger than normal.
The joint enlargement and flattening of the humeral head results in loss of motion.
There is loss of the uniformly white articular cartilage on the surface of the
humeral head, and there is proliferation of bone (osteo- phyte) along the
periphery of the humeral head. The head becomes flattened and larger, sometimes
resembling a mushroom. In most cases of osteoarthritis, the humeral head is
well centered within the center of the glenoid in anteroposterior radiographs.
This is defined as the center of the humeral head being close to the midline of
the center of the glenoid. Another method of assessing this alignment is a
smooth and continuous scapulohumeral line at the inferior part of the humeral
neck (Maloney line). This is a result of an intact rotator cuff. A continuous
Maloney line is not seen when the rotator cuff is damaged, as seen on the
anteroposterior radiographs in rotator cuff tear arthropathy (see Plates 1-49
and 1-50. With large and massive rotator cuff years there is superior migration
of the humeral head with narrowing of the subacromial space. In some cases of
more advanced osteoarthritis there is posterior glenoid bone loss associated
with posterior translation in the humeral head that is best seen on an axillary
radiograph or on an axial CT scan. The more advanced pathologic changes are
more difficult to correct with joint replacement.
The clinical findings of advanced
osteoarthritis are significant loss of passive (stiffness) and active
(pain-related) glenohumeral motion. Significant pain in the shoulder is
typically along the anterior and post- erior joint line with deep palpation.
Advanced-stage osteoarthritis is often treated by total shoulder arthroplasty.
Total-shoulder arthroplasty involves osteotomy (removal) of the humeral head at
the anatomic neck (see Plates 1-1 and 1-45) and insertion of a stem down the medullary
canal to which is attached an anatomically sized and positioned prosthetic
humeral head. In addition, there is the preparation of the glenoid bone surface
to correct pathologic version and insertion of a plastic glenoid component.
After total shoulder arthroplasty with an intact rotator cuff without severe
glenoid bone loss, there is restoration of the normal anatomic relationships
between the humeral head center and glenoid center line on both the
anteroposterior and axillary radiographs.
Nonoperative treatment for early and
midstage arthritis would include modification activities, oral anti-inflammatory
medication, and, occasionally, corticosteroid injection (see Plate 1-54). Viscosupplementation
with high-molecular-weight hyaluronic acid (see Plate 1-54) injected into the
joint over a series of three to five injections spaced 1 week apart has been
used as an effec- tive nonoperative treatment for knee and shoulder osteoarthritis.
