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Review Question - QID 216831

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QID 216831 (Type "216831" in App Search)
A 67-year-old male presents to your office with the radiographs shown in Figure A. He underwent reverse shoulder arthroplasty (RSA) approximately 4 years ago by an outside surgeon. Overall he is doing well, and presents to establish care as he just moved to the area. Which of the following most likely happened at the time of surgery?
  • A

Inoculation of the wound with an indolent bacteria

2%

32/2040

Glenosphere placed with too much inferior tilt

2%

36/2040

Glenosphere placed too superiorly

91%

1849/2040

Polyethylene depth is too shallow

1%

12/2040

Over lateralization of the center of rotation

4%

79/2040

  • A

Select Answer to see Preferred Response

Scapular notching following reverse shoulder arthroplasty (RSA) occurs with placement of the glenosphere too superiorly or with superior tilt.

Scapular notching is a phenomenon unique to RSA, and is caused by mechanical impingement between the humeral component and the neck of the glenoid. This can cause wear of the polyethylene and consequent osteolysis of the surrounding bone. To prevent this phenomenon the glenosphere should be placed as inferiorly as possible on the glenoid face and with inferior tilt. This finding can often be observed without further treatment as long as the components remain well fixed.

Gutiérrez et al evaluated shoulder abduction range of motion in relation to scapular notching. They report that the neck-shaft angle and position of the glenosphere had the largest effects on inferior scapular impingement. They conclude that these factors should be considered when deciding on sizing and positioning of implants for patients undergoing RSA in an attempt to avoid scapular notching.

Lévigne et al review the significance of scapular notching in patients with RSA. They report that scapular notching occurs in 68% of RSA and typically appears early with variable progression. They conclude that it's crucial to avoid cranial position and superior tilt of the glenosphere to avoid this complication.

Cheung et al review complications in reverse total shoulder arthroplasty. They report that the increased use of primary RSA has led to reports of associated problems unique to this procedure. They conclude that the most common complications include neurologic injury, periprosthetic fracture, hematoma, infection, scapular notching, dislocation, mechanical baseplate failure, and acromial fracture.

Figure A is a radiograph demonstrating inferior scapular notching in a patient following RSA.

Incorrect Answers:
Answer 1: While infections with low virulent organisms do occur in the shoulder, you would not expect to see significant bone erosion with this type of prosthetic joint infection.
Answer 2: Inferior tilt of the glenosphere is thought to decrease the incidence of scapular notching.
Answer 4: Reducing the depth of the polyethylene inlay increases range of motion and lowers the risk of notching.
Answer 5: Medialization, not lateralization of the center of rotation may lead to notching.

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