The Inlay Structure Can Improve Bone Graft Stability in Bristow Procedure.

BACKGROUND: Compared with the Latarjet procedure, the Bristow procedure has a lower screw-related complication rate but poor bone healing. A modified Inlay Bristow procedure has been reported to significantly improve the bone healing rate, but the biomechanical mechanism is unclear. The aim of this study was to evaluate the biomechanical stability of the bone graft between a modified Inlay Bristow procedure and the classic Bristow procedure.

METHODS: Sixteen left scapula models (Sawbones, Composite Scapula, 4th generation) were randomly divided into two groups (8:8). The bone graft in the first group was fixed with a 3.5 mm screw using the Inlay structure. The bone graft in the second group was fixed with a 3.5 mm screw via the traditional method. The maximum cyclic displacement, ultimate failure load and stiffness were evaluated biomechanically. The failure type was recorded for each model.

RESULTS: Cyclic loading tests demonstrated that the maximum cyclic displacement of the Inlay procedure was significantly smaller (P = 0.001) than that of the classic procedure. The Inlay Bristow technique resulted in a significantly higher (P = 0.024) ultimate failure load than the classic Bristow technique. The stiffness of the classic group was 19.17±4.01 N/mm and that of the inlay group was 22.34±5.35 N/mm (P = 0.232). Failure was mainly due to bone graft fractures through the drill hole or glenoid bone fractures.

CONCLUSION: Inlay Bristow fixation of the bone graft in a Sawbones model provides significantly stronger fixation and better time point zero stability than classic Bristow fixation, suggesting a higher likelihood of graft union.