title: In vivo degradation characteristics of bioabsorbable cross-pins in anterior cruciate ligament reconstruction.
abstract: BACKGROUND
  We evaluated degradation of bioabsorbable femoral cross-pins following anterior cruciate ligament (ACL) reconstruction.
  
  
  METHODS
  Four patients underwent ACL reconstruction using hamstring autograft with femoral fixation provided by a polylactic acid/polyglycolic acid copolymer (LactoSorb L15) cross-pin. Serial computed tomography (CT) scans were performed of the reconstructed knees at approximately 6 weeks, 4 months, 1 year and 2 years, postoperatively. A radiologist evaluated the scans for density of pins and surrounding bone and pin morphology.
  
  
  RESULTS
  The cross-pins demonstrated a relative reduction in density of 7.7%, 49.1%, and 75.0% at 4 months, 1 year and 2 years, respectively. Bone density values adjacent to the pin decreased by an mean of 8.6% between 6 weeks and 4 months. At one year an additional 14.2% reduction in bone density was seen but at 2 years the relative reduction in bone density had decreased to 7.4%. Evaluation of pin morphology revealed that minimal change had occurred after 6 weeks. At 4 months all of the pins were showing some morphologic changes on the surface, but none had fractured. After 1 year, two of the pins had fractured. By 2 years all of the pins had fractured. None of the pins had completely reabsorbed at 2 years postoperatively.
  
  
  CONCLUSIONS
  LactoSorb L15 cross-pins for femoral fixation in ACL reconstruction remain largely unchanged 4 months postoperatively, suggesting that this device maintains the necessary structural integrity to allow early integration of soft tissue grafts within bone tunnels.
  
  
  METHODS
  IV, case series.
authors.affiliation: OSU Sports Medicine, The Ohio State University, Columbus, OH 43221, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Parsons
authors.forename: Joseph
authors.initials: J
authors.lastname: Yu
authors.forename: Angela D
authors.initials: AD
authors.lastname: Pedroza
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Kaeding
mesh_terms: D020341:Absorbable Implants; D000328:Adult; D059549:Anterior Cruciate Ligament Reconstruction; D001672:Biocompatible Materials; D015519:Bone Density; D001858:Bone Nails; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging*; D019344:Lactic Acid; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D011091:Polyesters; D011100:Polyglycolic Acid; D011108:Polymers; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D001672:Biocompatible Materials; D011091:Polyesters; D011108:Polymers; D011100:Polyglycolic Acid; D019344:Lactic Acid; C033616:poly(lactide)