Evaluation of the Rough Shoulder.
Last updated Thursday, February 10, 2005
Five areas of smoothness
There are five areas in which smoothness is required for shoulder function.Cartilage articulations Three of these are cartilage to cartilage articulations: the
glenohumeral, acromioclavicular, and sternoclavicular joints. These
joints are stabilized by joint capsules, ligaments, and intraarticular
labra or menisci. The smoothness of their cartilage surfaces is at risk
for congenital, metabolic, traumatic, degenerative, septic, and non
septic inflammatory joint disease. By selecting the links in the
paragraphs below, you can see some of the necessary and sufficient
criteria we use in making different diagnoses of shoulder roughness.Five areas Collapse of the bone supporting the joint surface may be caused by avascular necrosis,
tumor, or osteomyelitis. Labral tears or loose bodies may become
interposed between the articular surfaces, causing joint roughness.
At the glenohumeral joint, different processes produce different patterns of joint surface destruction.
In degenerative joint disease,
the glenoid cartilage and subchondral bone are typically worn
posteriorly, sometimes leaving intact articular cartilage anteriorly.
The cartilage of the humeral head is eroded in a "Friar Tuck" pattern
of central baldness, often surrounded by a rim of remaining cartilage
and osteophytes. If similar findings arise after an injury or other
cause, the condition is called secondary degenerative joint disease.
In inflammatory arthritis, such as rheumatoid arthritis of the shoulder, the cartilage is usually destroyed evenly across the humeral and glenoid joint surfaces.
Cuff tear arthropathy
occurs when a chronic large rotator cuff defect subjects the uncovered
humeral articular cartilage to abrasion by the undersurface of the
coracoacromial arch. The erosion of the humeral articular cartilage
begins superiorly rather than centrally. Neurotrophic arthropathy
arises in association with syringomyelia, diabetes, or other causes of
joint denervation. The joint and subchondral bone are destroyed because
of the loss of the trophic and protective effects of its nerve supply.
In capsulorrhaphy arthropathy,
prior surgery for glenohumeral instability leads to joint surface
destruction. In this situation excessive anterior or posterior
capsulorrhaphy produces obligate translation, which forces the head of
the humerus out of its normal concentric relationship with the glenoid
fossa. The eccentric glenohumeral contact increases contact pressures
and joint surface wear. Most commonly, over tightening of the anterior
capsule produces obligate posterior translation, posterior glenoid
wear, and central wear of the humeral articular cartilage.
The other two locations requiring smoothness are atypical articulations: the scapulothoracic motion interface and the nonarticular humeroscapular motion interface. In these locations, motion occurs between tissue planes rather than at joints lined with articular cartilage.
Malalignment of the sliding surfaces, surface irregularities, or
thickening of interposed tissue can interfere with smooth motion at
these articulations. One of the more common of these clinical
conditions is subacromial abrasion. Smoothness and motion The concepts of smoothness and motion are closely related. If the
glenohumeral joint surfaces are rough because of degenerative
glenohumeral joint disease, for example, the shoulder will have a
marked tendency to become stiff. Restoration of function to such a
joint may require not only a resurfacing arthroplasty to restore
glenohumeral smoothness but also a capsular release and tendon
lengthening to restore motion. Yet lack of smoothness and stiffness
need not coexist. Avascular necrosis with collapse of subchondral bone
deprives the shoulder of normal smoothness but is not usually
associated with stiffness. Conversely, a frozen shoulder deprives a
shoulder of its motion, yet joint surface roughness is not present.
Because these two parameters of normal joint function are
distinguishable and require separate and distinct treatment, we discuss
them in two different sections.
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