Oblique fractures of the medial malleolus can arise from the application of axial force at various anatomic positions of the ankle, including supination-external rotation, pronation-external rotation, or pronation abduction. Although a variety of techniques exist to provide fixation of horizontal medial malleolus fractures, the optimal technique and pattern for internal fixation remains unclear. The aim of this study was to evaluate the mechanical properties of four different fixation methods for fractures of the medial malleolus.
Identical oblique osteotomies were created in synthetic distal tibiae using a jig. The specimens were divided into four fixation groups: contoured 2.0 mm mini-fragment T-plate, figure-of-eight tension band wire, construct two parallel 4.0 mm cancellous screws, and two divergent 4.0 mm cancellous screws. The specimens were tested using offset axial tension at 10 mm/min until 2 mm of joint line displacement.
The average stiffness in tension and force at 2 mm of joint line displacement of the plate construct was significantly greater than any of the other constructs (p < 0.05), whereas the average stiffness in tension of the other three groups were not significantly different from each other (p > 0.05).
Using a contoured 2.0 mm mini-fragment T-plate as the method of fixation resulted in an at least 25% stiffer construct during tension and required at least 24% more force for 2 mm of joint line displacement when compared with more traditional methods of fixation in an osteotomy model of an oblique medial malleolus fracture.
V, therapeutic study.
From the Department of Orthopedic Surgery (D.F.A., A.S., S.L., A.C., S.C., P.R.W.), University of California, Davis, Sacramento, California; and Department of Orthopaedic Surgery (E.M.D.), UCSF/SFGH Orthopaedic Trauma Institute, San Francisco, California.
Submitted: September 2, 2011, Revised: December 9, 2011, Accepted: January 3, 2012.
Supported by a grant from the AO North America Resident Research Support Program. All implants required to conduct this study were generously donated by Synthes, Inc. (West Chester, PA).
Presented at the AO North America, Orthopaedic Research Society, and Orthopaedic Trauma Association meetings.
Address for reprints: Philip R. Wolinsky, MD, Department of Orthopedic Surgery, 4860 Y St, Suite 3800, University of California, Davis, Sacramento, CA 95817; email: firstname.lastname@example.org.