title: Quadrupled semitendinosus-gracilis autograft fixation in the femoral tunnel: a comparison between a metal and a bioabsorbable interference screw.
abstract: Although semitendinosus-gracilis (SG) grafts for anterior cruciate ligament reconstruction have many potential benefits, effective fixation remains a challenge. This study assessed differences between the maximum pullout forces needed to detach a quadrupled SG graft from a femoral tunnel when secured by either a metal or a bioabsorbable interference screw. Sixteen paired fresh frozen quadrupled SG autografts (x, 8.4 mm; range, 7-10 mm) from 8 donors were anchored into cadaveric femoral tunnels by either a 7-mm metal or a 7-mm bioabsorbable screw after bone mineral density (BMD) assessment and before undergoing a longitudinal 20 mm/min traction force. Statistical analysis compared BMD (gm/cm2), insertional torque (N-m), and maximum load at pullout (N) between screw types. Insertional torques (.28-1.21, N-m range) did not correlate (P>.05) to BMD or maximum load at pullout (x +/- S.D.) 242 +/- 90.7 N (metal screw) and 341.1 +/- 162.9 N (bioabsorbable screw). Differences did not exist between the maximum load at pullout for bioabsorbable or metal screw fixation (P = .16). Careful graft preparation, sizing, and matched tunnel placement enables interference fit and fixation capable of reliably withstanding the low-level rehabilitation loads to which the graft is exposed until bony ingrowth occurs.
authors.affiliation: Division of Orthopaedic Surgery, The University of Kentucky School of Medicine, Lexington, USA.
authors.forename: D N
authors.initials: DN
authors.lastname: Caborn
authors.forename: M
authors.initials: M
authors.lastname: Coen
authors.forename: R
authors.initials: R
authors.lastname: Neef
authors.forename: D
authors.initials: D
authors.lastname: Hamilton
authors.forename: J
authors.initials: J
authors.lastname: Nyland
authors.forename: D L
authors.initials: DL
authors.lastname: Johnson
mesh_terms: D000042:Absorption; D000368:Aged; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001696:Biomechanical Phenomena; D015519:Bone Density; D001863:Bone Screws; D005260:Female; D005269:Femur / Q000601:surgery*; D006801:Humans; D066298:In Vitro Techniques; D019344:Lactic Acid; D008297:Male; D008875:Middle Aged; D011091:Polyesters; D011108:Polymers; D013710:Tendons / Q000637:transplantation*
chemical_list: D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide)