title: Biomechanical evaluation of bioabsorbable versus metallic screws for posterior cruciate ligament inlay graft fixation: a comparative study.
abstract: BACKGROUND
  Although a tibial inlay technique for posterior cruciate ligament reconstruction is advantageous, metallic screw fixation of the bone block is required. This may pose problems for future surgery (eg, osteotomies, total knee replacement).
  
  
  OBJECTIVE
  There is no significant difference in the biomechanical integrity of bone block fixation using stainless steel versus bioabsorbable screw fixation of the tibial inlay graft in posterior cruciate ligament reconstruction.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Fourteen human cadaveric knees were randomized to receive either stainless steel or bioabsorbable screw fixation of a bone-patellar tendon-bone graft. Cyclic tensile testing of each construct was performed, followed by a load-to-failure test. Digital video digitization was used to optically determine tendon graft deformation.
  
  
  RESULTS
  Cyclic creep deformation showed no significant difference between the 2 groups (P = .8). The failure load (stainless steel, 461 +/- 231 N; bioabsorbable, 638 +/- 492 N; P = .7) and linear stiffness (stainless steel, 116 +/- 22 N/mm, bioabsorbable, 106 +/- 44 N/mm; P = .6) also showed no significant difference between the 2 groups. Optically measured graft deformation was not significant for distal (P = .7) and midsubstance (P = .8) regions, while proximal deformation was significantly higher for bioabsorbable fixation (P = .02). All samples failed at the tibial insertion site with the tibial bone block fracturing at the screws.
  
  
  CONCLUSIONS
  Bioabsorbable screw fixation using a tibial inlay technique does not compromise the strength and stiffness characteristics afforded by metallic fixation. From a biomechanical perspective, bioabsorbable screws are a viable alternative to metal in the context of tibial inlay reconstruction.
  
  
  CONCLUSIONS
  Use of bioabsorbable fixation can potentially eliminate future hardware problems after posterior cruciate ligament reconstruction using a tibial inlay technique.
authors.affiliation: Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois, USA.
authors.forename: Aman
authors.initials: A
authors.lastname: Gupta
authors.forename: Christian
authors.initials: C
authors.lastname: Lattermann
authors.forename: Matthew
authors.initials: M
authors.lastname: Busam
authors.forename: Andrew
authors.initials: A
authors.lastname: Riff
authors.forename: Bernard R
authors.initials: BR
authors.lastname: Bach
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Wang
mesh_terms: D020341:Absorbable Implants; D001696:Biomechanical Phenomena; D001863:Bone Screws; D050376:Bone-Patellar Tendon-Bone Grafting / Q000295:instrumentation*; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016119:Posterior Cruciate Ligament / Q000601:surgery*; D011897:Random Allocation; D013314:Stress, Mechanical