Review Question - QID 216817

This patient has glenohumeral osteoarthritis with a biconcave posterior glenoid wear. Early component loosening is associated with insufficient glenoid bone stock (ie. posterior glenoid wear)

Glenoid component loosening is the most common cause of TSA failure (30% of primary OA revisions). Risk factors include insufficient glenoid bone stock (ie. posterior glenoid wear) and rotator cuff deficiency. There is a 2.9% reoperation rate for loosening (28% with revision). Interestingly, the presence of radiographic lines does not correlate with symptoms; however, the progression of a radiographic line does correlate with symptoms. Moreover, radiolucency around the glenoid does not always correlate with clinical failure. Posterior subluxation was associated with glenoid erosion and posterior humeral head subluxation.

Iannotti et al. evaluated the influence of an operatively confirmed full-thickness tear of the rotator cuff, the severity of preoperative erosion of glenoid bone, preoperative radiographic evidence of subluxation of the humeral head, and the severity of preoperative loss of the passive range of motion on the outcome of TSA and hemiarthroplasty. They reported that humeral head subluxation was associated with a less favorable result regardless of the type of shoulder arthroplasty. They concluded that a repairable tear of the supraspinatus tendon is not a contraindication to the use of a glenoid component.

Walch et al. reviewed the long-term glenoid migration patterns following TSA to better understand the factors responsible for loosening. They reported that in some shoulders, the use of a keel or pegs to provide fixation of a polyethylene component in the absence of good support from subchondral bone may not be sufficient to resist compressive and eccentric forces, resulting in loosening. They concluded that preserving subchondral bone may be important for the long-term longevity of the glenoid component.

Figure A is the AP radiograph of the shoulder demonstrating end-stage glenohumeral osteoarthritis with humeral head osteophytes. Figure B is the axial CT image of the glenoid demonstrating posterior glenoid wear. Illustration A is the axial CT image demonstrating how to measure the glenoid version.

Incorrect Answers:
Answer 1: This patient does not have a disrupted Shenton's line suggesting intact rotator cuff
Answer 3: Humeral head osteophytes are indicative of glenohumeral arthritis, but is not a risk factor for glenoid component loosening
Answer 4: This patient's age is not a risk factor for glenoid component loosening
Answer 5: This patient has good quality rotator cuff musculature suggesting only fatty streaking of the muscles