title: Preparation and degradation characteristic study of bone repair composite of DL-polylactic acid/hydroxyapatite/decalcifying bone matrix.
abstract: OBJECTIVE
  To explore the preparative method and study the degradation characteristics of bone repair composite of DL-polylactic acid (PDLLA)/hydroxyapatite(HA)/decalcifying bone matrix (DBM) in vitro.
  
  
  METHODS
  An emulsion blend method was developed to prepare the composite of PDLLA/HA/DBM in weight ratio of PDLLA:HA:DBM = 1.5-2:1-1.5:1. The dynamic changes of weight, biomechanical property and pH value of PDLLA/HA/DBM and PDLLA in phosphate buffered saline (PBS, pH 7.4) were studied respectively through degradation tests in vitro.
  
  
  RESULTS
  Without being heated, PDLLA, HA and DBM could be synthesized with the emulsion blend method as bone composite of PDLLA/HA/DBM, which had both osteoconductive and osteoinductive effects. The diameter of the aperture was 100-400 microm and the gap rate was 71.3%. During degradation, the pH value of PDLLA solution decreased lightly within 2 weeks, but decreased obviously at the end of 4 weeks and the value was 4.0. While the pH value of PDLLA/HA/DBM kept quite steady and was 6.4 at the end of 12 weeks. The weight of PDLLA changed little within 4 weeks, then changed obviously and was 50% of its initial weight at the end of 12 weeks. While the weight of PDLLA/HA/DBM changed little within 5 weeks, then changed obviously and was 60% of the initial weight at the end of 12 weeks. The initial biomechanical strength of PDLLA was 1.33 MPa, decreased little within 3 weeks, then changed obviously and kept at 0.11 MPa at the end of 12 weeks. The initial biomechanical strength of PDLLA/HA/DBM was 1.7 MPa, decreased little within 4 weeks, then changed obviously and kept at 0.21 MPa at the end of 12 weeks.
  
  
  CONCLUSIONS
  The emulsion blend method is a new method to prepare bone repair materials. As a new bone repair material, PDLLA/HA/DBM is more suitable for regeneration and cell implantation, and the environment during its degradation is advantageous to the growth of bone cells.
authors.affiliation: Department of Orthopaedics, Daping Hospital/Research Institute of Surgery, Third Military Medical University, Chongqing 400042, China. dapingguke@163.com
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhao
authors.forename: Weihong
authors.initials: W
authors.lastname: Liao
authors.forename: Yuanliang
authors.initials: Y
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Pan
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
mesh_terms: D001672:Biocompatible Materials; D001704:Biopolymers; D015519:Bone Density / Q000502:physiology; D001857:Bone Matrix / Q000378:metabolism / Q000648:ultrastructure; D018786:Bone Substitutes / Q000737:chemistry / Q000494:pharmacology*; D001842:Bone and Bones / Q000187:drug effects / Q000502:physiology; D017886:Durapatite / Q000737:chemistry / Q000494:pharmacology*; D017102:Fracture Healing / Q000502:physiology; D050723:Fractures, Bone / Q000601:surgery*; D066298:In Vitro Techniques; D019344:Lactic Acid / Q000737:chemistry / Q000494:pharmacology*; D008422:Materials Testing; D016348:Osseointegration / Q000502:physiology; D011091:Polyesters; D011108:Polymers / Q000737:chemistry / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D013718:Tensile Strength
chemical_list: D001672:Biocompatible Materials; D001704:Biopolymers; D018786:Bone Substitutes; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D017886:Durapatite