Trabecular Bone Remodeling After Posterior Lumbar Interbody Fusion: Comparison of Three-Dimensional Porous Tantalum and Titanium-Coated Polyetheretherketone Interbody Cages.

Abstract

Retrospective cohort study. The criteria for determining completion of intervertebral stability after posterior lumbar interbody fusion (PLIF) remain controversial. Several new radiological indicators of bone growth and osteointegration have been established. We compared computed tomography (CT) findings related to osteointegration after PLIF with interbody cages of two different materials and designs. We retrospectively analyzed data from 103 patients who underwent PLIF with three-dimensional porous tantalum (Tn) cages or titanium-coated polyetheretherketone (TiP) cages. CT images obtained 3months and 1year after surgery were examined for trabecular bone remodeling (TBR), cancellous condensation (CC), and vertebral endplate cyst (VEC) formation. The incidences of each finding were compared by cage type, and rates of instrument failure and pseudarthrosis were determined. Three months postoperatively, 87% of the levels with Tn cages exhibited TBR, whereas 96% of those with TiP cages did not (P < .001). Most levels with Tn cages levels exhibited TBR and no CC 3months (81%) and 1 year (94%) after surgery. Although 78% of levels with TiP cages exhibited CC and no TBR 3months after surgery, 59% exhibited both CC and TBR 1 year after surgery. Significantly fewer VECs formed around the Tn cages than around the TiP cages both 3months (P = .002) and 1year (P < .001) after surgery. Implant-related problems occurred at levels that exhibited neither TBR nor CC. The porous tantalum cage may enable intervertebral stability that is comparable to bony fusion soon after surgery.