title: The influence of screw geometry on hamstring tendon interference fit fixation.
abstract: We used a standardized model of calf tibial bone to investigate the influence of screw diameter and length on interference fit fixation of a three-stranded semitendinosus tendon graft for anterior cruciate ligament reconstruction. Biodegradable poly-(L-lactide) interference screws with a diameter of 7, 8, and 9 mm and a length of 23 and 28 mm were used. We examined results in three groups of 10 specimens each: group 1, screw diameter equaled graft diameter and screw length was 23 mm; group 2, screw diameter equaled graft diameter plus 1 mm and screw length was 23 mm; group 3, screw diameter equaled graft diameter and screw length was 28 mm. The mean pull-out forces in groups 1, 2, and 3 were 367.2+/-78 N, 479.1+/-111.1 N, and 537.4+/-139.1 N, respectively. The force data from groups 2 and 3 were significantly higher than those from group 1. These results indicate that screw geometry has a significant influence on hamstring tendon interference fit fixation. Increasing screw length improves fixation strength more than oversizing the screw diameter. This is important, especially for increasing tibial fixation strength because the tibial graft fixation site has been considered to be the weak link of such a reconstruction.
authors.affiliation: Department of Trauma and Reconstructive Surgery, Sports Traumatology and Arthroscopy Service, Charité, Humboldt-University of Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Weiler
authors.forename: R F
authors.initials: RF
authors.lastname: Hoffmann
authors.forename: C J
authors.initials: CJ
authors.lastname: Siepe
authors.forename: S F
authors.initials: SF
authors.lastname: Kolbeck
authors.forename: N P
authors.initials: NP
authors.lastname: Südkamp
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D002417:Cattle; D004867:Equipment Design; D006801:Humans; D008875:Middle Aged; D011475:Prosthesis Failure; D019651:Plastic Surgery Procedures / Q000295:instrumentation; D018709:Statistics, Nonparametric; D013710:Tendons / Q000637:transplantation*; D013848:Thigh; D013977:Tibia / Q000601:surgery; D019415:Torque
chemical_list: D001672:Biocompatible Materials