title: Effectiveness of low-profile supplemental fixation in anterior cruciate ligament reconstructions with decreased bone mineral density.
abstract: OBJECTIVE
  The purpose of this study was to compare anterior cruciate ligament (ACL) fixation using a bioabsorbable interference screw (BIS) and a supplemental low-profile suture anchor (PushLock 4.5-mm polyetheretherketone anchor; Arthrex, Naples, FL) with a standard BIS fixation to determine if fixation methods were dependent on tibial bone mineral density (BMD).
  
  
  METHODS
  Ten matched pairs of fresh-frozen human female knee specimens (20 total) were harvested with specimen ages ranging from 40 to 65 years. The BMD for each specimen was determined with a dual-energy x-ray absorptiometry scanner. The specimens were divided into 2 groups, 1 with a BIS and the other with a BIS plus a PushLock. Tibial-sided ACL fixation with hamstring tendon grafts was performed on all the specimens. Then, load to failure and stiffness were biomechanically tested.
  
  
  RESULTS
  The BIS-plus-PushLock specimens had a significantly higher mean yield load compared with specimens with the BIS alone (702 N v 517 N, P = .047). However, in samples with lower bone density, there was no statistically significant difference in failure loads between fixation techniques (P = .8566 at BMD of 0.5 g/cm(2)). As the bone density of the samples increased, the failure loads increased for both techniques (P < .0001 for PushLock and P = .0057 for BIS). This BMD-associated increase was greater for the PushLock (P = .0148), resulting in a statistically significant difference in failure load at the upper range tested (P = .0293 at BMD of 0.9 g/cm(2)).
  
  
  CONCLUSIONS
  Supplemental fixation of ACL reconstructions with a PushLock is beneficial in persons with a normal BMD of the proximal tibia, but at a lower BMD, there was no difference in our study.
  
  
  CONCLUSIONS
  Individuals with normal BMDs may benefit from this supplemental fixation. However, caution should be used in postmenopausal women or individuals with chronic ACL injuries when using this fixation strategy.
authors.affiliation: Warren Alpert Medical School at Brown University/Rhode Island Hospital, Providence, Rhode Island, USA. bvopat@gmail.com
authors.forename: Bryan
authors.initials: B
authors.lastname: Vopat
authors.forename: David
authors.initials: D
authors.lastname: Paller
authors.forename: Jason T
authors.initials: JT
authors.lastname: Machan
authors.forename: Anthony
authors.initials: A
authors.lastname: Avery
authors.forename: Patrick
authors.initials: P
authors.lastname: Kane
authors.forename: Melissa
authors.initials: M
authors.lastname: Christino
authors.forename: Paul
authors.initials: P
authors.lastname: Fadale
mesh_terms: D020341:Absorbable Implants; D015502:Absorptiometry, Photon; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D001696:Biomechanical Phenomena; D015519:Bone Density; D001863:Bone Screws; D002102:Cadaver; D005260:Female; D006801:Humans; D016268:Internal Fixators; D007719:Knee Joint / Q000601:surgery; D008875:Middle Aged; D053441:Suture Anchors; D013710:Tendons / Q000601:surgery / Q000637:transplantation; D013718:Tensile Strength / Q000502:physiology; D013977:Tibia / Q000502:physiology* / Q000601:surgery