Suture Versus Screw Fixation of Displaced Tibial Eminence Fractures: A Biomechanical Comparison Matthew R. Bong, M.D., Anthony Romero, M.D., Erik Kubiak, M.D., Kazuho Iesaka, M.D., Ph.D., Christian S. Heywood, M.D., Fredrick Kummer, Ph.D., Jeffrey Rosen, M.D., and Laith Jazrawi, M.D. Purpose: Classification and treatment of tibial eminence fractures are determined by the degree of fragment displacement. A variety of surgical procedures have been proposed to stabilize displaced fractures using both open and arthroscopic techniques. Two common fixation techniques involve use of cannulated screws and sutures tied over an anterior tibial bone bridge. We are unaware of any biome- chanical studies that have compared the strength of various techniques of fixation. Type of Study: Biomechanical study in a cadaveric model. Methods: Seven matched pairs of fresh-frozen human cadaveric knees were stripped of all soft tissue except the anterior cruciate ligament (ACL). Simulated type III tibial eminence fractures were created using an osteotome. Fragments of each matched pair were randomized to fixation with either a single 4-mm cannulated cancellous screw with a washer or an arthroscopic suture technique using 3 No. 2 Fiberwire sutures (Arthrex, Naples, FL) passed through the tibial base of the ACL and tied over bone tunnels on the anterior tibial cortex. Specimens were then loaded with a constant load rate of 20 mm/min, and load-deformation curves were generated. The ultimate strength and stiffness were computed for each curve. The failure mode for each test was observed. A paired 2-tailed t test was used to determine the statistically significant difference between the two methods. Results: Specimens fixed with Fiberwire had a mean ultimate strength of 319 N with a standard deviation of 125 N. Those fixed with cannulated screws had a mean ultimate strength of 125 N with a standard deviation of 74 N. This difference was statistically significant (P = .0038). There was no significant difference between the mean stiffness of Fiberwire constructs (63 N; SD, 50 N) and the mean stiffness of the cannulated screw constructs (20 N; SD, 32 N). The failure modes of the Fiberwire constructs included 1 ACL failure, 3 failures of suture cutting through the anterior tibial cortex, and 3 of suture cutting through the tibial eminence fragment. The single mode of failure for the cannulated screw constructs was screw pullout of cancellous bone. Conclusions: The initial ultimate strength of Fiberwire fixation of tibial eminence fractures in these specimens was significantly stronger than that of cannulated screw fixation. Clinical Relevance: It appears that Fiberwire fixation of eminence fractures provides biomechanical advantages over cannulated screw fixation and may influence the type of treatment one chooses for patients with tibial eminence fractures. Key Words: Tibial eminence fracture—Displaced—Screw fixation—Suture fixation—Biomechanics. F ractures of the tibial eminence have been well described in the literature and are estimated to represent 14% of all anterior cruciate ligament (ACL) injuries. 1 These fractures have traditionally been con- sidered more common in children and adolescents, but recent reports in the literature suggest tibial eminence fractures may occur just as frequently in adults. 1-5 Meyers and McKeever 6,7 originally classified tibial eminence fractures according to the degree of frag- ment displacement. In this classification, type III tibial eminence fractures are defined as those with complete separation of the bone fragment with no bone appo- sition. Their recommendations for treatment depended on the degree of fragment displacement. They recom- mended open reduction and internal fixation for all From the Department of Orthopaedics, New York University– Hospital for Joint Diseases, New York, New York, U.S.A. Address correspondence and reprint requests to Laith M. Jazrawi, M.D., Department of Orthopaedics, NYU—Hospital for Joint Diseases, 301 East 17th St, Suite 1402, New York, NY 10003, U.S.A. E-mail: LJazrawi@aol.com © 2005 by the Arthroscopy Association of North America 0749-8063/05/2110-4256$30.00/0 doi:10.1016/j.arthro.2005.06.019 1172 Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 21, No 10 (October), 2005: pp 1172-1176