Friday, March 4, 2016

Glenoid deficiency - use of a mini-glenoid component in seven patients

Total shoulder arthroplasty using an inlay mini-glenoid component for glenoid deficiency: a 2-year follow-up of 9 patients.

From 2010 to 2013, these authors performed 388 primary TSAs and 53 revision shoulder arthroplasties. In 9 an inset mini-glenoid component was used because of glenoid bone loss and severe retroversion.  Six were primary arthroplasties and 3 were revisions (1 hemiarthroplasty conversion; 1 prior TSA with a loose glenoid and bone loss; and 1 case of  multiple revisions with severe medial glenoid bone loss.  Four shoulders were classified as Walch type A2 glenoids, 2 were classified as Walch type C, and 3 were unable to be classified.

Each patient had a custom glenoid model made from computed tomography reconstructions before surgery. The glenoid models were used to determine the location for the planned mini-glenoid component. 

The custom glenoid components used in this study were premanufactured by various companies. Each miniature glenoid contained a single central peg that measured less than 1 cm in depth.

These authors report on 7 of these patients (9 shoulders) for which two year followup was available. The patients were clinically improved and there were no revisions at two years.  

Comment: Glenoid bone deficiency creates challenges in glenoid component fixation.

This paper presents an approach using custom mini inlay glenoid components. Data on radiolucent lines at the time of followup are not provided in this report. Problems with glenoid component failure are usually not evident in the first two years (the period of follow-up for this study).  When a glenoid component fails the shoulder is left with even greater glenoid bone deficiency than before surgery.

As shown below, the mini-glenoid component does not cover the surface of the glenoid bone and may not resolve the potential for contact between the lateral glenoid bone and the medial humerus. The cost of this approach is not provided in the paper.

Our current practice is to avoid glenoid component implantation in situations where bone quantity and quality is marginal. We await further evidence on the longer term value of the mini glenoid.


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