title: Biomechanical investigation of two plating systems for medial column fusion in foot.
abstract: BACKGROUND
  Arthrodesis of the medial column (navicular, cuneiform I and metatarsal I) is performed for reasons such as Charcot arthropathy, arthritis, posttraumatic reconstruction or severe pes planus. However, the complication rate is still high and mainly resulting from inadequate fixation. Special plates, designed for medial column arthrodesis, seem to offer potential to reduce the complication rate. The aim of this study was to investigate biomechanically plantar and dorsomedial fusion of the medial column using two new plating systems.
  
  
  METHODS
  Eight matched pairs of human cadaveric lower legs were randomized in two groups and medial column fusion was performed using either plantar or dorsomedial variable-angle locking compression plates. The specimens were biomechanically tested under cyclic progressively increasing axial loading with physiological profile of each cycle. In addition to the machine data, mediolateral x-rays were taken every 250 cycles and motion tracking was performed to determine movements at the arthrodesis site. Statistical analysis of the parameters of interest was performed at a level of significance p = 0.05.
  
  
  RESULTS
  Displacement of the talo-navicular joint after 1000, 2000 and 4000 cycles was significantly lower for plantar plating (p≤0.039) while there was significantly less movement in the naviculo-cuneiform I joint for dorsal plating post these cycle numbers (p<0.001). Displacements in all three joints of the medial column, as well as angular and torsional deformations between the navicular and metatarsal I increased significantly for each plating technique between 1000, 2000 and 4000 cycles (p≤0.021). The two plating systems did not differ significantly with regard to stiffness and cycles to failure (p≥0.171).
  
  
  CONCLUSIONS
  From biomechanical point of view, although dorsomedial plating showed less movement than plantar plating in the current setup under dynamic loading, there was no significant difference between the two plating systems with regard to stiffness and cycles to failure. Both tested techniques for dorsomedial and plantar plating appear to be applicable for arthrodesis of the medial column of the foot and other considerations, such as access morbidity, associated deformities or surgeon's preference, may also guide the choice of plating pattern. Further clinical studies are necessary before definitive recommendations can be given.
authors.affiliation: Department of Foot and Ankle Surgery, Catholic Clinic Mainz, Mainz, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Simons
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: Theresia
authors.initials: T
authors.lastname: Sommerer
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: Ivan
authors.initials: I
authors.lastname: Zderic
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: Dieter
authors.initials: D
authors.lastname: Wahl
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, University Hospital Jena, Jena, Germany.
authors.forename: Mark
authors.initials: M
authors.lastname: Lenz
authors.affiliation: Technical University Varna, Varna, Bulgaria.
authors.forename: Hristo
authors.initials: H
authors.lastname: Skulev
authors.affiliation: Department of Trauma and Reconstructive Surgery, University Hospital Aachen, Aachen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Knobe
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: Boyko
authors.initials: B
authors.lastname: Gueorguiev
authors.affiliation: AO Research Institute Davos, Davos, Switzerland.
authors.forename: R Geoff
authors.initials: RG
authors.lastname: Richards
authors.affiliation: Department of Foot and Ankle Surgery, Catholic Clinic Mainz, Mainz, Germany.
authors.forename: Kajetan
authors.initials: K
authors.lastname: Klos
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001174:Arthrodesis / Q000295:instrumentation* / Q000379:methods; D001696:Biomechanical Phenomena; D001860:Bone Plates; D002102:Cadaver; D004868:Equipment Failure; D005260:Female; D033023:Foot Joints / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D008297:Male; D008682:Metatarsal Bones / Q000000981:diagnostic imaging / Q000601:surgery*; D008875:Middle Aged; D009038:Motion; D011897:Random Allocation; D013639:Tarsal Bones / Q000000981:diagnostic imaging / Q000601:surgery*; D016474:Weight-Bearing