title: Late degradation tissue response to poly(L-lactide) bone plates and screws.
abstract: Patients with fractures of the zygomatic bone were treated with high molecular weight poly(L-lactic) acid (PLLA) bone plates and screws. Three years after implantation four patients returned to our department with a swelling at the site of implantation. At the recall of the remaining patients we found an identical type of swelling after the same implantation period. To investigate the nature of the tissue reaction, eight patients were reoperated for the removal of the swelling. The implantation period of the PLLA material varied from 3.3 to 5.7 years. Microscopic evaluation and molecular weight measurements were performed. The excised material showed remnants of degraded PLLA material surrounded by a dense fibrous capsule. Ultrastructural investigation showed crystal-like PLLA material internalized by various cells. The results of this investigation suggest that the PLLA material slowly degrades into particles with a high crystallinity. The intra- and extracellular degradation rate of these particles is very low. After 5.7 years of implantation, these particles were still not fully resorbed.
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Hospital Groningen, The Netherlands.
authors.forename: J E
authors.initials: JE
authors.lastname: Bergsma
authors.forename: W C
authors.initials: WC
authors.lastname: de Bruijn
authors.forename: F R
authors.initials: FR
authors.lastname: Rozema
authors.forename: R R
authors.initials: RR
authors.lastname: Bos
authors.forename: G
authors.initials: G
authors.lastname: Boering
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000328:Adult; D000469:Alkaline Phosphatase / Q000378:metabolism; D001673:Biodegradation, Environmental; D001860:Bone Plates / Q000592:standards*; D001863:Bone Screws / Q000592:standards*; D003094:Collagen / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007773:Lactates / Q000009:adverse effects*; D019344:Lactic Acid; D008137:Longitudinal Studies; D008247:Lysosomes / Q000201:enzymology; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D008928:Mitochondria / Q000737:chemistry / Q000201:enzymology / Q000648:ultrastructure; D008933:Mitochondrial Swelling; D008970:Molecular Weight; D010588:Phagosomes / Q000648:ultrastructure; D011091:Polyesters; D011108:Polymers / Q000009:adverse effects*; D012086:Reoperation; D013379:Substrate Specificity; D015051:Zygomatic Fractures / Q000601:surgery*
chemical_list: D007773:Lactates; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D003094:Collagen; D007770:L-Lactate Dehydrogenase; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase