Resorbable cages for spinal fusion: an experimental goat model

A biomechanical cadaver study and an in vivo monosegmental spinal fusion study were performed to evaluate a novel bioresorbable poly-L-lactic acid (PLLA) cage. The yield strength of a spinal segment was chosen as the main design parameter for the resorbable cages to be used in a goat model. A 3-year in vivo study revealed a significantly faster and more complete fusion using PLLA cages as compared to titanium cages with the same dimensions. In the PLLA group, the intervertebral grafting height did not change and bone remodeling within the cage was completed 2 years after implantation. In terms of degradation of the PLLA, similar features were observed in vivo and in vitro. Degradation was almost completed 3 years after implantation. Tissue reaction was mild during the 3-year period.