title: Biomechanical comparison of 3.0 mm headless compression screw and 3.5 mm cortical bone screw in a canine humeral condylar fracture model.
abstract: OBJECTIVE
  To compare the biomechanical properties of simulated humeral condylar fractures reduced with one of two screw fixation methods: 3.0 mm headless compression screw (HCS) or 3.5 mm cortical bone screw (CBS) placed in lag fashion.
  
  
  METHODS
  Bilateral humeri were collected from nine canine cadavers. Standardized osteotomies were stabilized with 3.0 mm HCS in one limb and 3.5 mm CBS in the contralateral limb. Condylar fragments were loaded to walk, trot, and failure loads while measuring construct properties and condylar fragment motion.
  
  
  RESULTS
  The 3.5 mm CBS-stabilized constructs were 36% stiffer than 3.0 mm HCS-stabilized constructs, but differences were not apparent in quality of fracture reduction nor in yield loads, which exceeded expected physiological loads during rehabilitation. Small residual fragment displacements were not different between CBS and HCS screws. Small fragment rotation was not significantly different between screws, but was weakly correlated with moment arm length (R² = 0.25).
  
  
  CONCLUSIONS
  A CBS screw placed in lag fashion provides stiffer fixation than an HCS screw, although both screws provide similar anatomical reduction and yield strength to condylar fracture fixation in adult canine humeri.
authors.affiliation: Mishka Gonsalves, DVM, Animal Specialty Group, 4641 Colorado Blvd., Los Angeles, CA 90039, United States, Phone: +1 818 244 7977, Fax: +1 818 507 9418, E-mail: mishka.gonsalves@gmail.com.
authors.forename: Mishka N
authors.initials: MN
authors.lastname: Gonsalves
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Jankovits
authors.forename: Michael L
authors.initials: ML
authors.lastname: Huber
authors.forename: Adam M
authors.initials: AM
authors.lastname: Strom
authors.forename: Tanya C
authors.initials: TC
authors.lastname: Garcia
authors.forename: Susan M
authors.initials: SM
authors.lastname: Stover
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001863:Bone Screws; D004285:Dogs / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000662:veterinary; D006810:Humeral Fractures / Q000000981:diagnostic imaging / Q000601:surgery / Q000662:veterinary*; D011859:Radiography; D016474:Weight-Bearing
keywords: Headless compression; canine; humeral condylar fracture; lag screw