Biological Resurfacing of the Glenoid

The management of arthritis in the young poses a very difficult problem for patients and surgeons. Unfortunately, we know that even in the best hands joint replacements will wear out given enough time. In the young patient this poses a significant challenge, as they may need several replacements during their lifetime.

This is a problem for all joint replacement surgeons but shoulder replacements have a series of unique aspects. With all joints there are two sides, usually a ball and a socket of some sort. In the shoulder the upper part of thehumerus(arm bone) forms the ball and the glenoid (part of the shoulder blade or scapula) the socket. The glenoid is a very small socket. The shoulder is also completely dependant on muscles with very little inherent bony stability. This means that if the muscles fail then the shoulder can become unstable. An unstable joint can wear more quickly. Both of these factors mean that replacing the glenoid has been a very difficult challenge to achieve good fixation and longevity.

The two principal options available to surgeons in shoulder replacement have therefore been to perform a total shoulder replacement. This gives better pain relief but may have a higher chance of glenoid loosening over time. Or to just replace the humeral side of the joint acknowledging that the results may be less predictable in terms of pain relief but there is no glenoid to worry about - A difficult choice especially in the young with high demands, expectations and level of function.

A potential solution to this was the proposed BIOLOGICAL RESURFACING of the GLENOID. This involves using a natural biological substance to cover the glenoid instead of a joint replacement. This would be the ideal scenario of achieving good pain relief but without the problems of glenoid implant failure.

The concept dates back over 100 years however it was Burkhead and Hutton (1995) who popularised the technique. They initially used eitheranteriorcapsule or fascia lata graft. They reported excellent initial results with good pain relief and increased ROM at 2 years. Their mid-term 7 years results were equally as encouraging with good/excellent results in 86% of shoulders. Other units also demonstrated good results, with Lee et al showing 83% satisfaction at 2-10 years using ananteriorcapsule graft. Other forms of graft were also tried including Achillestendonandlateralmeniscus allografts. The benefits of the different grafts were theoretically bulkier materiel that would have long life and tissue that had better load bearing characteristics respectively. De Beer described anarthroscopic technique, using commercially available dermal tissue (GraftJacket). 23/32 patients had excellent or satisfactory results. This study also found that the graft appeared to incorporate into the host glenoid into “tissue similar to fibrocartillage” on MRI.

Over the last few years, unfortunately, longer-term studies have started to show that the initial promising results may not be sustainable. Strauss et al reported their series of 41 patients. 31 had hadlateralmeniscal allograft and 10 GraftJacket with a resurfacing hemiarthroplasty. They found that the GraftJacket group had a clinical failure rate of 70% at 2.3 years and thelateralmenisicus group 45% at 3.4 years. JJP Warner from Harvard found that 11/13 of his patients had persistent pain. There was loss of joint space in 100% and 10/13 required revision surgery to a total shoulder replacement. This paper highlighted that the results were significantlyinferiorto his results with either hemiarthroplastyor total shoulder replacement. Hammond et al compared a case-controlled group of patients having resurfacing hemiarthroplastyalone against a similar group having hemiarthroplastyand biological glenoid resurfacing. They found that the outcome measures in the hemi alone group were better both in pain relief and functional improvement. There was however a high revision to total shoulder replacement rate in both groups (6/23 hemis at 3.8 years and 12/21 hemi + biological resurfacing at 3.6 years).

Shoulder replacement in the young is a difficult problem and one that we have not yet found the solution to. Biological resurfacing of the glenoid promised a novel option however the results do not seem to better than current shoulder replacements and may have a higher rate of complications.

With ref. from- shoulderdoc.co.uk