Glenoid dysplasia with spinoglenoid notch cyst and deltoid enthesitis
Presentation
Pain in shoulder; known case of ankylosing spondylitis
Patient Data
Glenoid appears shallow and does not closely follow the humeral head with posterior labral tear.
Posterior subluxation of head of humerus seen.
Cystic lesion measuring approx. 17x 8.5 mm in the spinoglenoid notch causing scalloping of the posterior aspects of glenoid bone.
Edema is seen in infraspinatus muscle.
Marrow edema is seen involving posterior aspects of acromion process along the site of origin of deltoid muscle.
Supraspinatus and infraspinatus tendinosis is seen with subtle cortical irregularity along the attachment site.
Mild subscapularis tendinosis also seen.
Sclerosis and mild flattening is seen along superior aspects of head of humerus.
Tendinosis of intracapsular segment of biceps tendon is seen with possible interstitial tear.
Shoulder joint capsule appears mildly thickened.
Reduced glenohumeral joint space is seen with thinning/loss of articular cartilage, prominent marginal osteophytes along humeral articular aspects and subchondral cysts in glenoid.
Mild acromioclavicular joint arthropathy is seen with eburnation along articular aspects and subtle subchondral marrow edema.
Rest of the glenoid labrum appears degenerated.
Case Discussion
Shallow glenoid which does not closely follow humeral head with posterior labral tear and posterior subluxation of head of humerus consistent with glenoid dysplasia and posterior instability.
Spinoglenoid notch cyst causing scalloping of the posterior aspects of glenoid bone and resulting in edema in infraspinatus muscle, likely due to compression suprascapular nerve. This is likely a paralabral cyst secondary to posterior labral tear.
Enthesopathic changes with marrow edema involving marrow edema involving posterior aspects of acromion process along the site of origin of deltoid muscle. This has been described as a very specific sign for ankylosing spondylitis.
Significant secondary osteoarthrtic changes, likely due to glenoid dysplasia resulting in chronic atraumatic posterior instability.
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