Summary

This study aimed to investigate the bone fusion status of the implanted artificial bone for ABR with glenoid bone defect and its bone reaction on the glenoid, using CT images at one year post surgery. Medial displacement of 1.5mm in the artificial bone, but 93.5% of the cases showed bony fusion. In 77.4% of the cases, new bone formation was observed like to be remodeling.

Abstract

Introduction

Glenoid bone defects has been found to contribute to recurrent instability after arthroscopic Bankart repair (ABR) alone. To address these issues, we are currently performing an ABR using double anchor footprint fixation (DAFF) with artificial bone graft augmentation (NEOBONE X II; Aimedic MMT, Tokyo, Japan) for anatomical glenoid reconstruction without sacrificing autologous tissue. The purpose of this study was to investigate the bone fusion status of the implanted artificial bone and its bone reaction on the neck of the glenoid using CT images.

Materials And Methods

Thirty-one cases of arthroscopic artificial bone grafting performed from January 2016 to December 2022 were included in this study. Imaging analysis utilized CT images taken 12 months post-operation to measure the positioning and angulation of the artificial bone relative to the glenoid surface, comparing immediate postoperative images to those at the final images. Furthermore, the bone fusion state at the final images was assessed by dividing the artificial bone into six segments along the upper, middle, and lower sections, and additionally into lateral (glenoid side) and medial halves, to evaluate bone fusion at each site. Any bone resorption of the glenoid or artificial bone was noted, and the size of the glenoid new bone formation were also measured.

Results

The average age was 32 years (17-73 years), with 22 males and 9 females. The average bone defect was 19.9±6.56%. The mean follow-up period was 16.2 months with no re-dislocation, and the average Rowe score was 94.4±6.42. The position of the artificial bone was 0.3±1.55mm from glenoid surface immediately after surgery and finally 1.8±1.35mm, a 1.5±1.10mm shifted to medial (far from glenoid surface). The average inclination angle of the artificial bone changed from 27.7 degrees immediately after surgery to 17.4 degrees at the final observation, aligning more with the glenoid surface. Bone fusion was observed in 29 cases (93.5%) at the middle of the lateral (glenoid) side with no bone resorption between the glenoid and artificial bone. Twenty-four cases (77.4%) showed new bone formation at the glenoid surface, with 8.7±7.31mm in length and 2.1±1.28mm in width. New bone formation on the glenoid side of the artificial bone formed as if the glenoid was enlarged.

Conclusion

One year post arthroscopic artificial bone grafting, CT imaging showed an average medial displacement of 1.5mm in the artificial bone, but 93.5% of the cases showed bony fusion. Furthermore, in 77.4% of the cases, new bone formation was observed as if the glenoid had been enlarged, which was considered to be remodeling.