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Journal of Long-Term Effects of Medical Implants
SJR: 0.332 SNIP: 0.491 CiteScore™: 0.89

ISSN Print: 1050-6934
ISSN Online: 1940-4379

Journal of Long-Term Effects of Medical Implants

DOI: 10.1615/JLongTermEffMedImplants.v15.i2.20
pages 125-138

Four-Year Follow-Up of Poly-L-Lactic Acid Cages for Lumbar Interbody Fusion in Goats

Martijn van Dijk
Departments of Orthopaedic Surgery, Vrije Universiteit Medical Center; and Skeletal Tissue Engineering Group Amsterdam (STEGA Foundation), Amsterdam, The Netherlands
Paul J. van Diest
Departments of Pathology, Vrije Universiteit Medical Center, Amsterdam, The Netherlands
Theo H. Smit
Departments of Physics and Medical Technology, Vrije Universiteit Medical Center; and Skeletal Tissue Engineering Group Amsterdam (STEGA Foundation), Amsterdam, The Netherlands
Hans Berkhof
Departments of Epidemiology, Vrije Universiteit Medical Center, Amsterdam, The Netherlands
Elisabeth H. Burger
Department of Oral Cell Biology, ACTA-Vrije Universiteit; and Skeletal Tissue Engineering Group Amsterdam (STEGA Foundation), Amsterdam, The Netherlands
Paul I. J. M. Wuisman
Departments of Orthopaedic Surgery, Vrije Universiteit Medical Center; and Skeletal Tissue Engineering Group Amsterdam (STEGA Foundation), Amsterdam, The Netherlands

ABSTRACT

Background. New applications of bioabsorbable polymer implants demand for histologic evaluation because a host tissue response is elicited and late complications after polymer implantation have been reported. Furthermore, in load-bearing regions an accelerated polymer degradation and foreign body reaction may be observed. Methods. Lumbar interbody fusion procedures were performed using poly-L-lactic acid (PLLA) and titanium cages in 43 goats. At 3, 6, 12, 24, 36, and 48 months after surgery, sequential histologic analysis of instrumented motion segments, lymph nodes, and nervous structures was performed. Blood samples were retrieved for laboratory analysis. Results. No adverse local or distant histologic or systemic effects were observed during the absorption of the poly-L-lactic acid cages. Interbody fusion was maintained, and only a very mild inflammatory response was observed. In half the specimens complete absorption was observed, and in the remaining specimens an estimated 1−10% of the original PLLA was present at the 3-year follow-up. At the 4-year follow-up, five out of seven PLLA specimens showed no PLLA particles under polarized light microscopy. In the remaining two specimens an estimated 1% of the original PLLA could be observed. Conclusions. Poly-L-lactic acid cages are feasible for lumbar interbody fusion, and the biocompatibility under high load bearing conditions is excellent during the complete absorption of the PLLA interbody fusion cages.