Reconstruction of segmental stability of goat cervical spine with poly (D, L) Lactide cage

Abstract

Objective To design a type of poly (D, L) Lactide (PDLLA) cage, compare the characteristics of inter body fusion using PDLLA cage with those of titanium cage and autologous tricortical iliac crest graft in a goat cervical spine model in vivo. Methods Twenty-four goats underwent C3-4 discectomy and fusion were assigned to 3 groups, PDLLA cage group (n=8), titanium alloy cage group (n=8) and autologous iliac bone group (n=8). Radiography was performed pre- and post-operatively and 1, 2, 4, 8, and 12 weeks after operation. At the same time points, disc space height (DSH), intervertebral angle (IVA), and lordosis angle (LA) were measured. After 12 weeks, the goats were killed and fusion sites were harvested. Biomechanical testing was performed in flexion, extension, axial rotation, and lateral bending to determine the stiffness and range of motion. All cervical fusion specimens underwent histomorphological observation. Results The IVA of PDLLA cage 4 weeks after operation and DSH 8 and 12 weeks after operation was statistically greater than that of autologous iliac bone graft (P 0.05). Radiographic and histomorphological observation showed better fusion results in cage groups than in autologous bone group. Conclusion This type of PDLLA cage has excellent biocompatibility and can provide an appropriate biological environment for bone ingrowth and osteogenesis at bone-implant interface. Furthermore, PDLLA cage can maintain DSH and increase the stability of fusion segments to create a good biomechanical environment for the last bone fusion. Key words: Cervical vertebrae; Spinal fusion; Animal experimentation; Biomechanics