Restoration of anterior glenoid bone defects in posttraumatic recurrent anterior shoulder instability using the J-bone graft shows anatomic graft remodeling.

BACKGROUND: The J-bone graft technique has previously been reported for anatomic restoration of the bony glenoid surface in cases of posttraumatic recurrent anterior shoulder instability with significant glenoid bone loss.

PURPOSE: To analyze the physiological remodeling process of the J-bone graft over time.

STUDY DESIGN: Case series; Level of evidence, 4.

METHODS: Thirty-one consecutive patients treated with anatomic glenoid restoration surgery using the J-bone graft for posttraumatic recurrent anterior shoulder instability with a significant bony glenoid defect were included in this study. Twenty patients received 3-dimensional computed tomography scans of the affected shoulder preoperatively, postoperatively, and at 1-year follow-up. On "en face" views of the glenoid, the change over time of the glenoid diameter, glenoid area, and glenoid defect size in relation to a best-fit circle indicating 100% was measured.

RESULTS: The average glenoid diameter increased from 81.0% preoperatively to 110.4% postoperatively (P < .001). At 1-year follow-up, the diameter had decreased significantly to 100.6% (P < .001), which is concordant to a theoretical perfect glenoid diameter of 100% (P = .73). The average glenoid surface area increased from 80.8% preoperatively to 110.0% postoperatively (P < .001). At 1-year follow-up, a decrease to 102.2% (P < .005) was measured, which again is close to a theoretical perfect glenoid surface area of 100% (P = .15). By applying the J-bone graft, the average missing surface area of the glenoid was reduced from 19.2% preoperatively to 3.9% postoperatively (P < .001). At 1-year follow-up, an average of 3.6% was calculated, indicating no statistically significant change over time (P = .90).

CONCLUSION: Anatomic glenoid reconstructive surgery using the J-bone graft technique benefits from a physiological remodeling process, molding the bone graft closely into the original shape of an uninjured anterior glenoid rim. While parts of the graft lying inside the projected former surface area of the glenoid are preserved, the parts lying outside are resorbed over time, suggestive of strain-adapted graft remodeling.