title: Bioabsorbable poly-L-lactic acid cages for lumbar interbody fusion: three-year follow-up radiographic, histologic, and histomorphometric analysis in goats.
abstract: METHODS
  Long-term evaluation was performed for bioabsorbable poly-L-lactic acid cages in a goat interbody fusion model.
  
  
  OBJECTIVE
  To assess the radiographic, histologic, and histomorphometric characteristics of poly-L-lactic acid cages during 3 years of follow-up evaluation.
  
  
  BACKGROUND
  Failed cage fusions may be related to cage design and material in addition to the surgical technique used. To overcome material-related complications and to explore the potential benefits of bioabsorbable cages, poly-L-lactic acid cages have been designed.
  
  
  METHODS
  For this study, 36 Dutch milk goats underwent a lumbar interbody fusion procedure (L3-L4). Two types of custom-made cage devices were impacted with bone graft and implanted: poly-L-lactic acid cages (n = 30) and titanium cages (n = 6). Sequential harvesting of surgically managed motion segments (intervals: 3, 6, 12, 24, and 36 months) was performed for analysis.
  
  
  RESULTS
  In poly-L-lactic acid specimens, permanent interbody fusion could be achieved within 6 months after surgery with maintenance of cage height. Titanium specimens showed no interbody fusion within this period. Radiographic follow-up evaluation (6-36 months) showed interbody fusion in 86% (19/22) of poly-L-lactic acid specimens, as compared with 33% (2/6) of titanium specimens. After 36 months of implantation, in one half of the specimens, poly-L-lactic acid cages were completely absorbed. Bone histomorphometry showed complete bone remodeling after 2 years of follow-up evaluation. During the study period, no local or distant adverse histologic effects were observed.
  
  
  CONCLUSIONS
  The current study showed that poly-L-lactic acid cage devices are feasible for lumbar interbody fusion. New poly-L-lactic acid cages designed for clinical practice might be a viable alternative to current nonabsorbable cage devices.
authors.affiliation: Skeletal Tissue Engineering Group, Amsterdam, The Netherlands.
authors.forename: Martijn
authors.initials: M
authors.lastname: van Dijk
authors.forename: Theo H
authors.initials: TH
authors.lastname: Smit
authors.forename: Elisabeth H
authors.initials: EH
authors.lastname: Burger
authors.forename: Paul I
authors.initials: PI
authors.lastname: Wuisman
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D016723:Bone Remodeling / Q000187:drug effects; D004343:Drug Implants / Q000494:pharmacology*; D004548:Elasticity; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006041:Goats; D019344:Lactic Acid / Q000494:pharmacology*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D023421:Models, Animal; D010012:Osteogenesis / Q000187:drug effects; D011091:Polyesters; D011108:Polymers / Q000494:pharmacology*; D011859:Radiography; D013123:Spinal Fusion / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D013203:Staphylococcal Infections / Q000209:etiology; D013530:Surgical Wound Infection / Q000209:etiology; D013995:Time; D014025:Titanium / Q000009:adverse effects; D016896:Treatment Outcome
chemical_list: D004343:Drug Implants; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D014025:Titanium