Clinical and computed tomography-radiologic outcome after bony glenoid augmentation in recurrent anterior shoulder instability without significant glenoid bone loss

Abstract

Background: The presence of a significant bony defect in anterior shoulder instability cases warrants glenoid reconstruction surgery typically by means of an autograft. Some surgeons use the same graft techniques even in the absence of a significant bony defect, thus augmenting the glenoid surface. The goal of this study is to investigate the clinical and computed tomography-radiologic outcome after glenoid augmentation surgery.

Methods: Between 2006 and 2011, 11 patients with recurrent anterior shoulder instability and glenoid bone loss of 5% or less were treated with an iliac crest autograft. Of the patients, 9 were available for follow-up at a mean of 34.6 months (range, 12 to 80 months), including apprehension testing, Western Ontario Shoulder Instability Index, Rowe score, Simple Shoulder Value, and 3-dimensional computed tomography examination.

Results: The mean Rowe score achieved was 85.0 points (range, 51 to 100 points); Simple Shoulder Value, 80.5 points (range, 30 to 100 points); and Western Ontario Shoulder Instability Index, 373.5 points (range, 61 to 878 points). Two patients reported a recurrence of instability, and one featured a positive apprehension test. The mean glenoid surface area was 96.5% (95% confidence interval [CI], 95.5% to 97.4%) preoperatively, increased after graft implantation to 119.5% (95% CI, 105.6% to 133.3%), and decreased to 102.8% (95% CI, 98.6% to 107.1%) at follow-up, concordant to an intact glenoid surface area. From preoperatively to follow-up, the mean increase in glenoid surface area was 6.4% (95% CI, 2.1% to 10.6%; P = .008); in concavity diameter, 2.0 mm (95% CI, -0.9 to 4.9 mm; P = .168); in concavity depth, 0.9 mm (95% CI, 0.3 to 1.5 mm; P = .005); and in concavity retroversion, 2.4° (95% CI, -1.2° to 6.1°; P = .178).

Conclusion: Because of anatomic bony remodeling processes, glenoid augmentation surgery seems to be subject to extensive graft osteolysis and, consequently, unsatisfactory clinical outcome in terms of stability in some cases.

Keywords: J-bone graft; Shoulder instability; glenoid augmentation; glenoid defect; glenoid remodeling; shoulder dislocation.