TY - JOUR
T1 - Radiographic, histologic, and chemical evaluation of bioresorbable 70/30 poly-L-lactide-CO-D, L-lactide interbody fusion cages in a goat model
AU - Krijnen, Matthijs R
AU - Mullender, Margriet G
AU - Smit, Theo H
AU - Everts, Vincent
AU - Wuisman, Paul I J M
PY - 2006/6/15
Y1 - 2006/6/15
N2 - STUDY DESIGN: A study of lumbar interbody fusion using polylactic acid-based bioresorbable fusion cages in a goat model.OBJECTIVE: To evaluate the effect of polylactic acid polymer composition, and internal stabilization on the rate and quality of interbody fusion.SUMMARY OF BACKGROUND DATA: A spinal cage should provide an appropriate biomechanical environment to facilitate interbody fusion. Previous studies have shown that bioresorbable polylactic acid-based cages can provide adequate stability for spinal fusion. However, at present and to our knowledge, the best bioresorbable materials, optimal cage stiffness, and desired period over which the cage should biodegrade are unknown.METHODS: Interbody fusions were performed at L3-L4 level in 35 skeletally mature Dutch milk goats. Titanium and poly-L-lactide-CO-D,L-lactide (PLDLLA) cages were implanted at random as stand-alone cages. In addition, PLDLLA cages were implanted with anterior fixation. The goats were euthanized at 3, 6, or 12 months. Radiographic, magnetic resonance imaging, histologic, and histomorphometric analyses were performed on retrieved segments. Chemical analysis was used to assess degradation of the retrieved PLDLLA cages. Beforehand, chemical and mechanical degradation of the PLDLLA cages were assessed in vitro.RESULTS: At 3 months, bone graft was almost completely remodeled. Endochondral bone formation was observed in all specimens. At 6 months, 50% of the PLDLLA stand-alone cages and 83% of the PLDLLA anterior fixation cages were fused. At 12 months, 38% of the PLDLLA stand-alone and 83% of the titanium cages realized fusion. A very mild and dispersed foreign body reaction was seen in all PLDLLA specimens. E-beam sterilized PLDLLA cages degraded more rapidly in vivo as compared to both, PLDLLA cages in vitro, and ethylene oxide sterilized poly-L-lactic acid cages in vivo.CONCLUSIONS: Within the 3-6-month period, PLDLLA stand-alone cages provided insufficient mechanical stability, which manifested as cracking and deformation of the cages and lower fusion rates. This result implies that within this time, additional stabilization is required; supplemental internal fixation proved sufficient to obtain successful fusion. In all cases, only a mild host response was seen, indicating good biocompatibility.
AB - STUDY DESIGN: A study of lumbar interbody fusion using polylactic acid-based bioresorbable fusion cages in a goat model.OBJECTIVE: To evaluate the effect of polylactic acid polymer composition, and internal stabilization on the rate and quality of interbody fusion.SUMMARY OF BACKGROUND DATA: A spinal cage should provide an appropriate biomechanical environment to facilitate interbody fusion. Previous studies have shown that bioresorbable polylactic acid-based cages can provide adequate stability for spinal fusion. However, at present and to our knowledge, the best bioresorbable materials, optimal cage stiffness, and desired period over which the cage should biodegrade are unknown.METHODS: Interbody fusions were performed at L3-L4 level in 35 skeletally mature Dutch milk goats. Titanium and poly-L-lactide-CO-D,L-lactide (PLDLLA) cages were implanted at random as stand-alone cages. In addition, PLDLLA cages were implanted with anterior fixation. The goats were euthanized at 3, 6, or 12 months. Radiographic, magnetic resonance imaging, histologic, and histomorphometric analyses were performed on retrieved segments. Chemical analysis was used to assess degradation of the retrieved PLDLLA cages. Beforehand, chemical and mechanical degradation of the PLDLLA cages were assessed in vitro.RESULTS: At 3 months, bone graft was almost completely remodeled. Endochondral bone formation was observed in all specimens. At 6 months, 50% of the PLDLLA stand-alone cages and 83% of the PLDLLA anterior fixation cages were fused. At 12 months, 38% of the PLDLLA stand-alone and 83% of the titanium cages realized fusion. A very mild and dispersed foreign body reaction was seen in all PLDLLA specimens. E-beam sterilized PLDLLA cages degraded more rapidly in vivo as compared to both, PLDLLA cages in vitro, and ethylene oxide sterilized poly-L-lactic acid cages in vivo.CONCLUSIONS: Within the 3-6-month period, PLDLLA stand-alone cages provided insufficient mechanical stability, which manifested as cracking and deformation of the cages and lower fusion rates. This result implies that within this time, additional stabilization is required; supplemental internal fixation proved sufficient to obtain successful fusion. In all cases, only a mild host response was seen, indicating good biocompatibility.
KW - Absorbable Implants
KW - Animals
KW - Biocompatible Materials
KW - Bone Remodeling
KW - Disinfection
KW - Equipment Failure
KW - Female
KW - Foreign-Body Reaction/chemically induced
KW - Goats
KW - Internal Fixators
KW - Lumbar Vertebrae/diagnostic imaging
KW - Magnetic Resonance Imaging
KW - Polyesters/adverse effects
KW - Radiography
KW - Spinal Fusion/instrumentation
KW - Time Factors
KW - Titanium
U2 - 10.1097/01.brs.0000221984.12004.3b
DO - 10.1097/01.brs.0000221984.12004.3b
M3 - Article
C2 - 16778688
VL - 31
SP - 1559
EP - 1567
JO - Spine
JF - Spine
SN - 0362-2436
IS - 14
ER -