Strength of ulnar fixation in ulnar collateral ligament reconstruction: a biomechanical comparison of traditional bone tunnels to the tension-slide technique Atiba Jackson, MD a , Tristan Maerz, MS b , Denise M. Koueiter, MS b , Christopher J. Andrecovich, BS b , Kevin C. Baker, PhD b, *, Kyle Anderson, MD a a Department of Orthopaedic Surgery, William Beaumont Hospital, Royal Oak, MI, USA b Department of Orthopaedic Research, William Beaumont Hospital, Royal Oak, MI, USA Background: Surgical reconstruction of the ulnar collateral ligament after rupture has evolved substan- tially since the original description. Reconstruction techniques vary significantly at the ulnar and humeral interface. The purpose of this study was to develop a model to isolate, test, and compare the ulnar fixation of the traditional bone tunnel technique and a new technique, the tension slide. Materials and methods: Six matched pairs of cadaveric arms were dissected to isolate the ulna. Pairs were randomized to the bone tunnel or tension-slide ulnar fixation technique, and consistent tendon grafts were used for each reconstruction. A specialized tendon clamp was used to grip the grafts. Specimens were pre- loaded with a valgus force to 1 N,m and tested to failure in torsion at 4.5  /s. Statistical analysis was per- formed with 1-way analysis of variance with the Tukey post hoc test (a ¼ .05). Results: The bone tunnel technique exhibited higher initial and total stiffness, as well as higher torsional torque at 10  and 30  of valgus angulation and at ultimate failure. The tension-slide technique exhibited significantly higher angular displacement at 3 N,m but not at ultimate failure. The bone tunnel technique exhibited higher work at 10  and 30  of valgus angulation. Conclusion: In this model, traditional bone tunnels performed superior to the tension-slide construction in terms of both strength and stiffness. Whether there is a kinematic benefit to the tension slide, which moves the ulnar fixation to within the native ulnar collateral ligament footprint, is yet to be determined. Further study is needed to assess the clinical benefit of a stronger ulnar fixation. Level of evidence: Basic Science Study, Biomechanics, Cadaveric Model. Ó 2012 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Ulnar collateral ligament reconstruction; biomechanics; bone tunnels; tension slide; ulnar fixa- tion; interference screw The ulnar collateral ligament (UCL) is an important valgus stabilizer of the elbow. 11,23 The UCL complex is divided into the anterior bundle, the posterior bundle, and the transverse ligament. 23 The anterior bundle is the primary restraint and stabilizer to valgus stress and is functionally composed of anterior and posterior bands. The isometric point of the ligament is located at the central fibers between the anterior and posterior bands. 17 Overhead-throwing athletes risk injury to the UCL because of the high valgus loads placed on the ligament, 10 Institutional review board approval: not applicable. *Reprint requests: Kevin C. Baker, PhD, William Beaumont Hospital, 3811 W 13 Mile Rd., Ste 404, Royal Oak, MI 48073, USA. E-mail address: kevin.baker@beaumont.edu (K.C. Baker). J Shoulder Elbow Surg (2012) 21, 1674-1679 www.elsevier.com/locate/ymse 1058-2746/$ - see front matter Ó 2012 Journal of Shoulder and Elbow Surgery Board of Trustees. doi:10.1016/j.jse.2012.03.017