title: Intraosseous fixation compared to plantar plate fixation for first metatarsocuneiform arthrodesis: a cadaveric biomechanical analysis.
abstract: BACKGROUND
  Metatarsocuneiform (MTC) fusion is a treatment option for management of hallux valgus. We compared the biomechanical characteristics of an internal fixation device with plantar plate fixation.
  
  
  METHODS
  Seven matched pairs of feet from human cadavers were used to compare the intramedullary (IM) device plus compression screw to plantar plate combined with a compression screw. Specimen constructs were loaded in a cyclic 4-point bending test. We obtained initial/final stiffness, maximum load, and number of cycles to failure. Bone mineral density was measured with peripheral quantitative computed tomography. Performance was compared using time to event analysis with number of cycles as time variable, and a proportional hazard model including shared frailty model fitted with treatment and bone mineral density as covariates.
  
  
  RESULTS
  On average the plates failed after 7517 cycles and a maximum load of 167 N, while the IM-implants failed on average after 2946 cycles and a maximum load of 69 N. In all pairs the 1 treated with IM-implant failed earlier than the 1 treated with a plate (hazard ratio for IM-implant versus plate was 79.9 (95% confidence interval [6.1, 1052.2], P = .0009). The initial stiffness was 131 N/mm for the plantar plate and 43.3 N/mm for the IM implant. Initial stiffness (r = .955) and final stiffness (r = .952) were strongly related to the number of cycles to failure. Bone mineral density had no effect on the number of cycles to failure.
  
  
  CONCLUSIONS
  Plantar plate fixation created a stronger and stiffer construct than IM fixation.
  
  
  CONCLUSIONS
  A stiffer construct can reduce the risk of nonunion and shorten the period of non-weight-bearing.
authors.affiliation: Center of Orthopedic and Trauma Surgery, University Medical Center of the Johannes Gutenberg University, Mainz, Germany eddi.roth@unimedizin-mainz.de.
authors.forename: Klaus Edgar
authors.initials: KE
authors.lastname: Roth
authors.affiliation: Center of Orthopedic and Trauma Surgery, University Medical Center of the Johannes Gutenberg University, Mainz, Germany.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Peters
authors.affiliation: Institute for Medical Biometry, Epidemiology and Computer Science, Johannes Gutenberg University, Mainz, Germany.
authors.forename: Irene
authors.initials: I
authors.lastname: Schmidtmann
authors.affiliation: Center of Orthopedic and Trauma Surgery, University Medical Center of the Johannes Gutenberg University, Mainz, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Maus
authors.affiliation: Institute for Biomechanics, Traumacenter, Murnau, Germany Paracelsus Medical University, Salzburg, Austria.
authors.forename: Daniel
authors.initials: D
authors.lastname: Stephan
authors.affiliation: Institute for Biomechanics, Traumacenter, Murnau, Germany Paracelsus Medical University, Salzburg, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Augat
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001174:Arthrodesis / Q000295:instrumentation*; D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D004867:Equipment Design; D004868:Equipment Failure; D005260:Female; D006215:Hallux Valgus / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D008297:Male; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed
keywords: Lapidus fusion; biomechanic testing; intramedullary implant; plantar angle stable plate