Monday, April 28, 2014

The glenoid component in total shoulder replacement

Over the course of the past 30 years there have been a lot of different implant designs introduced in the treatment of arthritis of the shoulder. Although most would think that the new implants will have better longevity it seems that this is not true. Based on the largest meta-analysis performed as of today (1) The survivorship of the glenoid component has not changed the past 30 years (data from 1976-2007) (2) Implant design does not affect the longevitity of the prosthesis (13 different implant designs examined) (3) American Shoulder and Elbow Society surgeon membership did not influence the results either

However, the pegged all polythelene glenoid components outperform the keeled in terms of survivorship (see  reference 1) and the metal backed glenoid components fail more often and by different modes compared to all polyethylene glenoid components (in print unpublished data).

Reference 1: http://www.ncbi.nlm.nih.gov/pubmed/24352774

On the modes of failure of the glenoid: http://www.ncbi.nlm.nih.gov/pubmed/18381328

Review on the evolution of the design of the glenoid component: http://reviews.jbjs.org/content/1/2/e2

We prefer to use the all polyethylene pegged cemented glenoid components which allow bone ingrowth at the fenestrations of the central peg. After drilling the hole for the central peg of the glenoid the bone removed is used as bone graft for the central peg.

The radiographs below demonstrate that at 4 months postop there is bony ingrowth at the fenestrations of the central peg and no radiolucent lines.



Radiographically at 10 years 50% of the glenoid components are loose. However the revision rate is low at that point and most of the glenoids "survive" to 10-15 years if the end point is considered to be revision for glenoid failure.