Enhanced spinal fusion using a biodegradable porous mesh container in a rat posterolateral spinal fusion model

Background context Posterolateral fusion (PLF) with an autogenous iliac bone graft is the most common procedure for treating various lumbar spinal diseases. However, the limited success and associated morbidity from an iliac crest graft demands new biologically competent graft enhancers or substitutes. Purpose To investigate the feasibility of tubular mesh container made of bioabsorbable sutures (poly-1,4-dioxane-2-one, PDO) for spinal fusion. Study design Experimental animal study. Methods A biodegradable PDO tubular mesh container was used to contain small pieces of bone grafts. Twenty Sprague-Dawley male rats underwent PLF between L4 and L5 transverse processes with bilateral iliac grafts. Experimental animals were assigned into two different groups: autograft-only group (N=10) that underwent PLF with autograft-only or mesh container group (N=10) that underwent PLF with tubular mesh container filled with autogenous bone grafts. The rats were sacrificed at 8 weeks postoperatively, and the lumbar spines were removed. Spinal fusion was evaluated by manual palpation, microcomputed tomography, three-point bending test, and histological examination. Results Solid fusion was achieved in all cases of the mesh container group, whereas the autograft-only group showed 60% of solid fusion. New bone mass was higher and more solidly fused in the mesh container group than the autograft-only group (p<.01). Volume of fusion mass and density of bone were significantly higher in the mesh container group (p<.05). In all cases, inflammatory response was minimal. Conclusions This study demonstrated that a tubular mesh container made of bioabsorbable suture is useful to hold small pieces of bone grafts and to enhance spinal fusion.