Biomechanical performance of a new device for medial malleolar fractures

Tejas Patel, John R. Owen, William A. Byrd, Ryan B. Graves, Ruchi D. Chande, Varatharaj Mounasamy, Robert S. Adelaar, Jennifer S. Wayne

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Background: Displaced medial malleolus fractures require surgical repair because of the critical role the structure plays in normal joint function. Various approaches exist, but options are limited for small fragment fractures. This study compared repair with the Medial Malleolar Sled fixation system (Trimed, Inc, Valencia, CA) to lag screws in 2 modes of biomechanical loading in a cadaveric model. Methods: A Müller type B medial malleolus fracture was simulated on matched pairs of cadaveric lower extremities and repaired with the sled or 2 cancellous lag screws. Tibial distraction (tension, n = 10) or internal rotation (torsion, n = 11) was applied. Fragment movement was measured in the sagittal (tension and torsion) and transverse (torsion-only) planes. Fragment movement at 1 mm and 2 mm (clinical malunion) of gapping during tension and at 2, 4, 6, and 8 N-m during torsion was analyzed via paired t tests. Results: In tension, the load at the 2-mm gap was statistically lower for screws (P = .026). Opening angle was statistically larger for the sled at the 1-mm (P = .0004) and 2-mm (P = .008) gap. In torsion, gapping was statistically lower for the sled (ranging from P = .0013 at 4 N-m to P = .0187 at 8 N-m). No differences were detected for opening angle or transverse plane movement. Conclusion: The sled appeared stronger in tension and as effective as lag screws in torsion. The sled may be a viable option for fractures too small for 4.0- or 3.5-mm lag screws. Clinical Relevance: The sled may be suitable in applications where a tension band would normally be considered and may provide stronger fixation in osteoporotic bone compared with lag screw fixation.

Original languageEnglish (US)
Pages (from-to)426-433
Number of pages8
JournalFoot and Ankle International
Issue number3
StatePublished - Mar 2013
Externally publishedYes


  • Biomechanics
  • Cadaver study
  • Fracture fixation
  • Medial malleolus
  • Tibia
  • Trauma

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine


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