To minimize glenoid bone graft resorption, bone block size must match glenoid bone loss for patients with shoulder instability.

Abstract

Despite having similar clinical outcomes, allograft bone blocks have higher resorption rates when compared to autograft bone block (approximately 75% versus 15%) for treating glenoid bone loss and recurrent anterior shoulder instability. The resorption of both autografts and allografts are based on Wolff's Law of bone remodeling. The physiological loading of the humeral head on the glenoid will strengthen bone blocks lying within the normal glenoid surface area. Any bone graft outside of this area will not be placed under any load and will be resorbed. Several studies have shown significant graft resorption of excess bone block over the first 6-12 months postoperatively, followed by a stable glenoid construct similar in size to that of the native glenoid. To minimize graft resorption, the size of the bone block, autograft, or allograft should be size matched to the amount of glenoid bone loss. The tendency to oversize bone blocks to maximize glenoid surface area and prevent instability should be avoided. Excess bone graft beyond the normal glenoid surface will be resorbed. Because allograft bone blocks tend to be larger than autograft, this is likely why resorption rates are so much higher for allografts. Since both grafts will eventually remodel to the native glenoid width, outcomes will be the same, and excessive graft resorption can lead to complications.