Saturday, November 1, 2014

The variable biconcave glenoid, a challenge for fitting posteriorly augmented and step-cut components

Quantification of the position, orientation, and surface area of bone loss in type B2 glenoids

These authors evaluated 55 type B2 glenoids using computed tomography to create three-dimensional reconstructions.

They found the maximal erosion was usually posterior - inferior (8 o'clock in the right shoulder and 4 o'clock in the left shoulder), but there was a substantial degree of variability.  The line of erosion was curved in 35% of the cases. The pathological concavity accounted for an average of 44% ±  12% of the overall glenoid surface. The pathological concavity was flatter (radius 37mm ± 8) in comparison to the normal glenoid (radius 34mm ± 7). 

Comment: It would be of interest to know what percent of the total population of arthroplasty shoulders these 55 B2 glenoids represented.

The authors point out that the challenges in fitting the variable B2 pathology (such as that shown above) with posteriorly augmented or step-cut glenoid components.

Reaming and subsequent bone removal to accommodate posteriorly built-up glenoid components carries the risk of excess bone removal, reducing the quality and quantity of the remaining glenoid bone and leading to potentially compromised implant stability.

In our approach to prosthetic glenoid arthroplasty, we do not attempt to correct glenoid version, but rather we ream the glenoid bone as conservatively as possible to a single concavity, preserving glenoid bone stock.

As suggested in another recent related article "Glenoid component loosening in total shoulder arthroplasty may be prevented by component placement on a congruent and adequate bony surface."

Consultation for those who live a distance away from Seattle.

Click here to see the new Shoulder Arthritis Book

Click here to see the new Rotator Cuff Book

To see the topics covered in this Blog, click here

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and runreverse total shoulderCTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'