title: Bioabsorbable Versus Titanium Screws in Anterior Cruciate Ligament Reconstruction Using Hamstring Autograft: A Prospective, Blinded, Randomized Controlled Trial With 5-Year Follow-up.
abstract: BACKGROUND
  Longer-term results of bioabsorbable screws for anterior cruciate ligament reconstruction (ACLR) have been reported, but results are specific to the exact screw material and design. Titanium and poly-L-lactic acid with hydroxyapatite (PLLA-HA) screw outcomes have been compared only to 2 years.
  
  
  OBJECTIVE
  The purpose of this study was to compare the clinical and radiologic outcomes of the PLLA-HA screw versus titanium screw for hamstring tendon ACLR over a 5-year follow-up period. The hypothesis was that there are no differences in clinical scores or tunnel widening between the PLLA-HA and the titanium screws and that the PLLA-HA screw as seen on magnetic resonance imaging (MRI) should show high-grade resorption and ossification response over 5 years.
  
  
  METHODS
  Randomized controlled trial; Level of evidence, 1.
  
  
  METHODS
  A total of 40 patients undergoing ACLR were randomized to receive either a PLLA-HA screw (PLLA-HA group) or a titanium screw (titanium group) for ACL fixation. Blinded evaluation was performed at 2 and 5 years with the International Knee Documentation Committee and Lysholm knee score, KT-1000 arthrometer, single-legged hop test, and MRI to evaluate tunnel and screw volumes, periscrew ossification, graft integration, and cyst formation.
  
  
  RESULTS
  There was no difference in any clinical outcome measure at 2- or 5-year follow-up between the 2 groups. At 2 years, the femoral tunnel in the PLLA-HA group was smaller than that in the titanium group (P = .02); at 5 years, there was no difference. At 2 years, the femoral PLLA-HA screw was a mean 76% of its original volume, and by 5 years, it was 36%. At 2 years, the tibial PLLA-HA screw mean volume was 68% of its original volume, and by 5 years, it was 46%. At 5 years in the PLLA-HA group, 88% of femoral tunnels and 56% of tibial tunnels demonstrated a significant ossification response. There was no increase in cyst formation in the PLLA-HA group and no screw breakages.
  
  
  CONCLUSIONS
  There were equivalent clinical results between the PLLA-HA and titanium groups at 2- and 5-year follow-ups. The PLLA-HA screw was not associated with increased tunnel widening or cyst formation when compared with the titanium screw. The PLLA-HA screw demonstrated progressive screw resorption and gradual but incomplete ossification over 5 years.
authors.affiliation: North Sydney Orthopaedic and Sports Medicine Centre, Sydney, Australia.
authors.forename: Yuval
authors.initials: Y
authors.lastname: Arama
authors.affiliation: North Sydney Orthopaedic and Sports Medicine Centre, Sydney, Australia.
authors.forename: Lucy J
authors.initials: LJ
authors.lastname: Salmon
authors.affiliation: North Sydney Orthopaedic and Sports Medicine Centre, Sydney, Australia.
authors.forename: Kesavan
authors.initials: K
authors.lastname: Sri-Ram
authors.affiliation: Castlereagh Imaging, Sydney, Australia.
authors.forename: James
authors.initials: J
authors.lastname: Linklater
authors.affiliation: North Sydney Orthopaedic and Sports Medicine Centre, Sydney, Australia The Mater Hospital, Sydney, Australia.
authors.forename: Justin P
authors.initials: JP
authors.lastname: Roe
authors.affiliation: North Sydney Orthopaedic and Sports Medicine Centre, Sydney, Australia The Mater Hospital, Sydney, Australia Notre Dame University, Sydney, Australia lpinczewski@nsosmc.com.au.
authors.forename: Leo A
authors.initials: LA
authors.lastname: Pinczewski
mesh_terms: D020341:Absorbable Implants; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D001863:Bone Screws; D004311:Double-Blind Method; D017886:Durapatite / Q000737:chemistry; D005260:Female; D005269:Femur / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D019344:Lactic Acid / Q000737:chemistry; D008297:Male; D018482:Muscle, Skeletal / Q000601:surgery; D011091:Polyesters; D011108:Polymers / Q000737:chemistry; D011446:Prospective Studies; D013710:Tendons / Q000637:transplantation; D013977:Tibia / Q000601:surgery; D014025:Titanium / Q000737:chemistry; D014182:Transplantation, Autologous; D055815:Young Adult
chemical_list: D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D017886:Durapatite; D014025:Titanium
keywords: ACL; bioabsorbable; clinical; fixation