Sunday, November 1, 2015

Repost - anteriorly augmented polyethylene glenoid or posteriorly eccentric humeral head.

One of our regular readers pointed out that the prior post on this topic omitted the great post now added at the end showing the functional result after a posteriorly eccentric humeral head with a ream and run. So here it is again with the case added at the bottom - check it out.

Total shoulder arthroplasty with an augmented component for anterior glenoid bone deficiency.

These authors present 5 patients having total shoulder arthroplasty using an anteriorly augmented glenoid component. The preoperative diagnoses were anterior glenoid erosion in 2 patients, and 1 patient each with malunited glenoid fracture, nonunited glenoid fracture, and post-traumatic arthritis. The mean age at the time of surgery was 67.4 years (range, 53-75 years).

At an average of 33.2 months (range, 21.9-43.2 months) after surgery no patient had demonstrated radiographic or clinical signs of glenoid component loosening or instability. 

Comment: Anterior glenoid erosion predisposes the shoulder to anterior instability. As shown in this figure from the paper, it can usually be identified on a standardized axillary x-ray.
These authors have reported the use of an augmented glenoid component in the management of five such shoulders with durable results.

An alternative approach is to use a posteriorly eccentric humeral head component with a standard glenoid component accepting the glenoid anteversion as shown in the case below. This approach preserves the maximal amount of glenoid bone stock.

The posteriorly eccentric humeral head component has also improved useful in the management of failed arthroplasty with anterior glenoid bone deficiency, again accepting the anteversion of the glenoid.

The posteriorly eccentric humeral head can also manage post traumatic deformity in which the head is posteriorly malunited.