Graft Laceration and Pullout Strength of Soft-Tissue Anterior Cruciate Ligament Reconstruction: In Vitro Study Comparing Titanium, Poly-D,L-Lactide, and Poly-D,L-Lactide–Tricalcium Phosphate Screws Thore Zantop, M.D., Andre Weimann, M.D., Romana Schmidtko, M.S., Mirco Herbort, M.S., Michael J. Raschke, M.D., and Wolf Petersen, M.D. Purpose: The aim of part 1 of this study was to compare the structural properties of tibia– graft– interference screw constructs of soft-tissue graft fixation via the anterior cruciate ligament (ACL) by use of different interference screws. In part 2 the influence of graft laceration as a result of 1 single interference screw insertion on the mechanical properties of the graft was evaluated. Methods: In part 1 of the study, in a bovine knee model, soft-tissue graft fixation with titanium, biodegradable poly-D,L-lactide (PLDLA), and PLDLA–tricalcium phosphate (TCP) interference screws was per- formed, and the structural properties were determined by use of a materials testing machine at a rate of 12.5 mm/s. In part 2 the bone was cut after 1 single insertion of titanium, PLDLA, or PLDLA-TCP interference screws, and the mechanical properties of the graft were determined. Results: Soft-tissue graft fixation with a biodegradable PLDLA interference screw showed a statistically significantly higher maximum load when compared with PLDLA-TCP and titanium interference screws. PLDLA- TCP screw fixation revealed a significantly higher ultimate load than titanium screw fixation. The mechanical properties of the grafts after 1 single insertion of PLDLA-TCP interference screws showed a statistically significantly higher stiffness, yield load, and maximum load when compared with the PLDLA and titanium interference screw groups. Conclusions: The results of this study suggest that the use of a titanium screw to fix a soft-tissue graft in cruciate ligament reconstruction surgery may cause damage to the graft. Soft-tissue ACL reconstruction fixed with a PLDLA interference screw resulted in a significantly higher pullout strength than ACL reconstructions fixed with a PLDLA-TCP or titanium interference screw. Clinical Relevance: In contrast to fixation with a biodegradable interference screw, fixation with a titanium interference screw may damage the integrity of a soft-tissue graft in cruciate ligament reconstruction and should therefore be avoided. Key Words: Biodegradable implants—Osteoconductive—Graft damage—Revision—Properties. A lthough there is still a controversial debate about the most appropriate graft for anterior cruciate ligament (ACL) reconstruction, the use of 4-strand hamstring tendons (semitendinosus and gracilis) is a topic of increasing interest because their harvest causes less donor-site morbidity and functional deficit than the bone–patellar tendon– bone graft. 1-4 A disadvantage is that tendon-to-bone healing of hamstring grafts requires a longer time for graft incorporation than bone-to-bone healing of bone–patellar tendon– bone grafts. 3,5-9 Many techniques have been used for the fixation of hamstring grafts to the bone tunnel. 3 Extra-articular graft From the Department of Trauma, Hand, and Reconstructive Surgery, Wilhelms University (T.Z., A.W., M.H., M.J.R., W.P.), Muenster; and Department of Orthopaedic Surgery, University of Schleswig-Holstein (R.S.), Kiel, Germany. The authors report no conflict of interest. Address correspondence and reprint requests to Thore Zantop, M.D., Department of Trauma, Hand and Reconstructive Surgery, Wilhelms University Muenster, Waldeyer Strasse 1, 48149 Muen- ster, Germany. E-mail: thore.zantop@ukmuenster.de © 2006 by the Arthroscopy Association of North America 0749-8063/06/2211-5110$32.00/0 doi:10.1016/j.arthro.2006.06.015 1204 Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 22, No 11 (November), 2006: pp 1204-1210