OUTCOMES OF AN ANTERIOR BONE BLOCK TECHNIQUE WITH ILIAC CREST ALLOGRAFT FOR THE MANAGEMENT OF ANTEROINFERIOR SHOULDER INSTABILITY WITH SUBCRITICAL GLENOID DEFECTS.

Abstract

Background: Glenoid bone defects play a significant role in anterior shoulder instability. Their management is controversial, and the use of anterior bone grafting is one appealing option. The purpose of this study is to assess the clinical and radiological outcomes at five-years follow-up of an arthroscopic bone block procedure with iliac crest allograft for the management of subcritical glenoid bone loss in subjects with recurrent anterior shoulder instability.

Methods: Prospective longitudinal study of a consecutive case-series of subjects with anterior glenohumeral instability and subcritical (between 8% and 17%) glenoid bone defects managed with an arthroscopic bone block procedure with iliac crest allograft fixed with a double-button system associated with a Bankart repair, and, when necessary, a Remplissage. Preoperative Computed tomogram (CT) scans were used to quantify the dimensions of the glenoid and the humeral bone defects. Postoperative CT scans one-month after surgery and at one-year follow-up were used to assess the graft's positioning, integration and resorption. Clinical assessment was performed using the Constant-Murley (CS) and Rowe (RS) scores preoperatively and at least three years follow-up.

Results: Fourteen subjects were included (all male, median age 27 years, interquartile range [IQR]=5.75), with a median of 8 (IQR=14) dislocation episodes before surgery and a median preoperative glenoid bone defect of 13% (IQR=14%, range: 9.3 to 15.4%). A remplissage was added in 12/14 cases (85.7%). Graft position was excellent in all cases (100%) in the axial plane and in 12 of 14 (85.7%) in the sagittal plane. The median reconstructed glenoid surface in the postoperative CT scan was 99.4% (IQR 2,1%, range: 96.6% to 100%). One-year postoperative CT scans showed bone resorption of ≥ 20% of volume in 13/14 cases (93%), with a median resorption of 80.3% (IQR=40.8%) of the graft volume. Graft integration was observed in 6/14 cases (42.8%). The median reconstructed glenoid surface decreased to 93.6% (IQR 2%, range: 87.5% to 97.3%) (p<0.0001). At the latest follow-up (58.9 months [IQR=11.2]: range: 39.6 to 67.8), two subjects (14.3%) presented with recurrence of instability. There were substantial improvements in the RS (from 25 [5] to 95 [6.2], p<0.0001) and in the CS (from 84 [5] to 94.5 [4.2] points, p<0.0001) at the final follow-up.

Conclusions: Arthroscopic bone block procedure employing an iliac crest allograft achieves accurate graft positioning and good clinical outcomes with low recurrence rates at a mean of five years follow-up. However, early graft resorption and low consolidation rates are worrisome issues that must be considered.