title: Dual small fragment plating improves screw-to-screw load sharing for mid-diaphyseal humeral fracture fixation: a finite element study.
abstract: BACKGROUND
  A smaller humerus in some patients makes the use of a large fragment fixation plate difficult. Dual small fragment plate constructs have been suggested as an alternative.
  
  
  OBJECTIVE
  This study compares the biomechanical performance of three single and one dual plate construct for mid-diaphyseal humeral fracture fixation.
  
  
  METHODS
  Five humeral shaft finite element models (1 intact and 4 fixation) were loaded in torsion, compression, posterior-anterior (PA) bending, and lateral-medial (LM) bending. A comminuted fracture was simulated by a 1-cm gap. Fracture fixation was modelled by: (A) 4.5-mm 9-hole large fragment plate (wide), (B) 4.5-mm 9-hole large fragment plate (narrow), (C) 3.5-mm 9-hole small fragment plate, and (D) one 3.5-mm 9-hole small fragment plate and one 3.5-mm 7-hole small fragment plate.
  
  
  RESULTS
  Model A showed the best outcomes in torsion and PA bending, whereas Model D outperformed the others in compression and LM bending. Stress concentrations were located near and around the unused screw holes for each of the single plate models and at the neck of the screws just below the plates for all the models studied. Other than in PA bending, Model D showed the best overall screw-to-screw load sharing characteristics.
  
  
  CONCLUSIONS
  The results support using a dual small fragment locking plate construct as an alternative in cases where crutch weight-bearing (compression) tolerance may be important and where anatomy limits the size of the humerus bone segment available for large fragment plate fixation.
authors.affiliation: Department of Orthopaedic Surgery, University of North Texas Health Science Center, Fort Worth, TX, USA Department of Materials Science and Engineering, University of North Texas, Denton, TX, USA.
authors.forename: Victor
authors.initials: V
authors.lastname: Kosmopoulos
authors.affiliation: Department of Orthopaedic Surgery, John Peter Smith Hospital, Fort Worth, TX, USA.
authors.forename: Colten
authors.initials: C
authors.lastname: Luedke
authors.affiliation: Department of Orthopaedic Surgery, University of North Texas Health Science Center, Fort Worth, TX, USA Department of Orthopaedic Surgery, John Peter Smith Hospital, Fort Worth, TX, USA.
authors.forename: Arvind D
authors.initials: AD
authors.lastname: Nana
mesh_terms: D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D020342:Finite Element Analysis; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D006810:Humeral Fractures / Q000601:surgery*; D008422:Materials Testing / Q000379:methods; D013314:Stress, Mechanical; D016474:Weight-Bearing
keywords: Finite element analysis; bone plates; humerus; internal fracture fixation; mechanical stress