title: Optimizing compression: Comparing eccentric plate holes and external tensioning devices.
abstract: OBJECTIVE
  Elimination of interfragmentary motion in fracture fixation using plates to impart compression and promote primary bone healing through absolute stability has been well described as a reliable and successful method to treat simple transverse and short oblique fracture morphologies. Our hypothesis is that dynamic compression plating augmented by external compression techniques would produce and maintain a significantly greater amount of compression than using the plate alone.
  
  
  METHODS
  Simple transverse diayphyseal fractures were simulated in nine 4th generation composite bone models. A load cell was placed within the transverse fracture osteotomy and stabilized and compressed using either eccentric screw placement in a dynamic compression plate alone or augmented with an opposite segment Verbrugge clamp or articulated tensioning device (ATD) compressing using a screw outside of the plate. Dynamic plate compression was evaluated independently and in conjunction with the external compression techniques. Statistical analyses were carried out using a linear mixed effects model and pairwise comparisons between conditions with a significance set at a P-value <0.05.
  
  
  RESULTS
  Both of the external compression techniques (Verbrugge and ATD) achieved significantly higher compression than the plate compression technique alone with 78% (P<0.001) and 134% (P<0.001) more compression respectively. The measured compression across the osteotomy after screw application and removal of external compression decreases by 17% for the Verbrugge device (P=0.215) and by 22%, after removal of the ATD device (P=0.038). For both techniques, adding additional screws in eccentric (load) position further increases compression.
  
  
  CONCLUSIONS
  Plate compression is a reliable method for inducing compression across transverse and short oblique fractures. Augmenting plate compression technique with external compression techniques (Verbrugge clamp or ATD) allows for a significantly greater compressive load to be achieved. Compression lost after removal of the external compression device indicates that the maximal compression attainable across a fracture may not be reliably maintained with standard dynamic compression plating techniques.
authors.affiliation: Department of Orthopedic Surgery, University of California at Davis, 4860 Y Street, Suite 3800, Sacramento, CA 95817, United States. Electronic address: Jflucas@ucdavis.edu.
authors.forename: Justin F
authors.initials: JF
authors.lastname: Lucas
authors.affiliation: Department of Orthopedic Surgery, University of California at Davis, 4860 Y Street, Suite 3800, Sacramento, CA 95817, United States. Electronic address: Marlee@ucdavis.edu.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Lee
authors.affiliation: Department of Orthopedic Surgery, University of California at Davis, 4860 Y Street, Suite 3800, Sacramento, CA 95817, United States. Electronic address: Jgeastman@ucdavis.edu.
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Eastman
mesh_terms: D001187:Artificial Organs; D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D001842:Bone and Bones; D004867:Equipment Design; D016267:External Fixators; D005264:Femoral Fractures / Q000601:surgery*; D005594:Fracture Fixation, Intramedullary / Q000295:instrumentation; D017102:Fracture Healing; D006801:Humans; D013314:Stress, Mechanical; D013718:Tensile Strength
keywords: Absolute stability; Articulated tensioning device; Clamp compression; Compression plating