title: Alendronate-eluting polyglucose-lignol composite (POGLICO): a new biomaterial for fracture fixating implants.
abstract: OBJECTIVE
  Due to the known drawbacks of metal implants, new biomaterials for internal fracture fixation are attracting increasing interest, among them poly(lactic-co-glucolic) acids (PLGAs) and the recently developed silk-tenoin derived materials (STDMs). In accordance with the new philosophy of bio-derived biomaterials (BIODERIBIOs), I describe a novel innovative technology for use in fracture fixation.
  
  
  METHODS
  Screws (2 mm dia.) were manufactured from cylindrical bars of polyglucose-lignol composite (POGLICO) in the form of birch toothpicks from the hospital canteen, dip-coated with alendronate (1 mg/mL, n=6) or saline (n=6), and inserted in the proximal tibias of rats for 4 weeks. Fixation was evaluated by mechanical pullout testing. POGLICO nails were inserted in the contralateral tibia for microCT and histology.
  
  
  RESULTS
  All POGLICO implants remained fixed in the bone (p<0.001) with a mean pullout force of 37 (SD 5.5) N. MicroCT showed that the control nails were surrounded by a thin layer of new bone, while all bisphosphonate-treated implants were surrounded by a thick layer of cancellous bone. Bisphosphonates more than doubled the bone density around the nails (p=0.004).
  
  
  CONCLUSIONS
  POGLICO is biocompatible, remains in situ, and appears to provide a higher resistance to pullout forces than bulk silk protein. The material is light, strong, and bio-derived. BIODERIBIO-POGLICO can be sterilized by autoclaving, and has a porous surface that can serve for slow release of drugs applied by simple dip-coating, as demonstrated by the effect of the alendronate treatment. As the raw material for the screws is readily available from the toothpick industry, I believe that the possibilities for commercial development of the material for fracture fixation are promising.
authors.affiliation: Department of Clinical and Experimental Medicine , Faculty of Health Sciences, Linköping University, Linköping , Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Aspenberg
mesh_terms: D019386:Alendronate / Q000494:pharmacology*; D000818:Animals; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D001863:Bone Screws; D020099:Coated Materials, Biocompatible / Q000494:pharmacology*; D005936:Glucans / Q000494:pharmacology*; D016268:Internal Fixators; D019344:Lactic Acid / Q000494:pharmacology; D008297:Male; D011100:Polyglycolic Acid / Q000494:pharmacology; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011859:Radiography; D011897:Random Allocation; D017207:Rats, Sprague-Dawley; D013978:Tibial Fractures / Q000000981:diagnostic imaging / Q000601:surgery*
chemical_list: D050071:Bone Density Conservation Agents; D020099:Coated Materials, Biocompatible; D005936:Glucans; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D019386:Alendronate