Degradation of PDLLA cage in the intervertebral fusion / 中国矫形外科杂志

ABSTRACT

[Objective]To observe the degradation process of PDLLA in the intervertebral fusion.[Method]Twenty goats were divided into 4 groups as experimental group,and their L_(3~4)intervertebal spaces were implanted with PDLLA cage containing pieces of graft bone.Animals were sacrificed at 4,8,12,16 wks and specimens were taken for observation of the degradation process and bone fusion by gross observation and electronic microscope.Another 12 goats were used as normal fusion control group.Their L_(3~4)space were grafted with bone block for fusion.[Result]The degradation rate was non-lineal.In the early stage of fusion,the main degradation and decrease of molecular weight was shown at the superficial decomposition.With the proceeding of fusion and degradation,as the kydrolyzation speeding-up,internal decomposition by self-catalyse resulted into the collapse and total disassemble of the PDLLA.The PDLLA cage maintained its shape in the early stage and its biomechanical strength decrease in late stage but was still enough to keep the structure from collapse,till the fusion was achieved in the bone implant area.[Conclusion]The velocity of degradation of PDLLA is slower than the speed of bone regeneration of bone fusion,so the PDLLA cage could provide sufficient support during the process of intervertebal fusion and is a suitable choice of degradative material for cage in the intervertebal fusion.