Review Question - QID 4532

The surgeon should consider eccentrically reaming the anterior glenoid when performing a total shoulder arthroplasty on a patient with a retroverted glenoid due to posterior deficiency associated with osteoarthritic changes which is most consistent with answer choice #2.

Normal version of the glenoid is 0-3 degrees of retroversion, but when doing a total shoulder the goal should be to place the glenoid component in neutral to slight anteversion. Reaming the anterior glenoid to neutral is a technique to be considered by the operative surgeon when presented with a patient undergoing total shoulder arthroplasty with a retroverted glenoid, as failure to perform this step increases the chance for glenoid loosening. If reaming down the anterior glenoid will take away too much bone stock (down to the coracoid process), one may consider bone grafting the posterior glenoid. To perform a total shoulder arthroplasty patients will need a functioning rotator cuff and appropriate glenoid bone stock.

Clavert et al. performed cadaveric analysis to simulate glenoid retroversion of greater than 15 degrees and found that retroversion to this degree cannot be safely corrected with eccentric anterior reaming when using a glenoid component with peripheral pegs due to penetration into the glenoid vault.

Nowak et al. used 3D-CT models of patients with advanced shoulder osteoarthritis with varying degrees of glenoid retroversion and simulated glenoid resurfacing. They found that smaller size glenoid components may allow for greater version correction when using in-line pegged components, as they would be less likely to result in peg penetration.

Illustration A shows >25 degrees of glenoid retroversion seen by axial radiograph of the shoulder in a patient with advanced osteoarthritis. In this case, anterior glenoid reaming is not the correct answer and a posterior glenoid allograft reconstruction would be appropriate.

Incorrect Answers:
Answer 1: This patient should undergo a reverse total shoulder due to the lack of rotator cuff where anterior glenoid reaming is not applicable.
Answers 3: Eccentric reaming is not a useful adjunct when the humerus is anteverted
Answer 4: Excessive glenoid retroversion requires allograft reconstruction of the posterior defect instead of anterior glenoid reaming
Answer 5: Eccentric reaming is contraindicated when bone stock is insufficient to allow it.