Intramedullary Screw Fixation of Jones Fractures: A Biomechanical Study

• Published in: Foot & ankle international 1999-09, Vol.20 (9), p.560-563
• Main Authors: Pietropaoli, Marc P., Wnorowski, Daniel C., Werner, Frederick W., Fortino, Maria D.
• Format: Article
• Language: English
• Subjects: Athletic Injuries - therapy; Biomechanical Phenomena; Bone Screws; Cadaver; Fracture Fixation, Internal - instrumentation; Fractures, Bone - surgery; Fractures, Bone - therapy; Humans; Metatarsal Bones - injuries; Metatarsal Bones - physiopathology; Models, Biological
• ISSN: 1071-1007; 1944-7876
• DOI: 10.1177/107110079902000904

The management of proximal fifth metatarsal (“Jones”) fractures in athletes has become increasingly more aggressive, despite a lack of biomechanical data in the literature. A cadaver biomechanical study was conducted to evaluate the strength of intramedullary fixation of simulated Jones fractures loaded to failure via three-point bending on a Materials Testing System machine. In a series of eight intact fifth metatarsal control specimens, the force to failure (fracture) was measured for comparison with repaired specimens. Acute fractures were simulated in 10 pairs of feet via osteotomy at the typical fracture location and were fixed with either a 4.5-mm malleolar screw or a 4.5-mm partially threaded, cancellous, cannulated screw, both placed using conventional intramedullary techniques. Force at initial displacement averaged 73.9 N (SD, 64.7 N) for the malleolar screws and 72.5 N (SD, 42.3 N) for the cannulated screws. Force at complete displacement averaged 519.3 N (SD, 226.2 N) for the malleolar screws and 608.4 N (SD, 179.7 N) for the cannulated screws. The force to failure of the intact specimens was significantly greater than the initial and complete forces to failure for the fixed specimens (P