title: Biomechanical strength of the Peri-Loc proximal tibial plate: a comparison of all-locked versus hybrid locked/nonlocked screw configurations.
abstract: OBJECTIVE
  The purpose of this study was to compare the biomechanical properties of a contoured locking plate instrumented with either an all-locked or hybrid locked/nonlocked screw construct in a proximal metaphyseal fracture of the tibia (AO 41-A3.2).
  
  
  METHODS
  A standardized proximal metaphyseal wedge osteotomy (AO 41-A3.2) was created in five pairs of cadaveric tibia. Each pair was randomly instrumented with either an all-locked or combination locked/nonlocked screw construct using a locked contoured periarticular plate (Peri-Loc periarticular locked plating system, Smith & Nephew, Memphis, TN). Vertical subsidence (irreversible deformation) and deflection (reversible deformation) in each pair were analyzed and compared. Load to failure, defined by complete fracture gap closure, was also determined.
  
  
  RESULTS
  There was no statistically significant difference in vertical subsidence (P = 0.19) or deflection (P = 0.19) of the proximal tibia between the all-locked and combination locked/nonlocked screw construct with increasing levels of cyclical axial load from 200 to 1200 N. Failure occurred at a mean value of 2160 N in the locked group and 1760 N in the hybrid group (P = 0.19); the failure mode was plate bending in all specimens.
  
  
  CONCLUSIONS
  The results indicate that the use of compression screws with locked screws in this particular construct allows a similar amount of irreversible and reversible deformation in response to an axial load when compared to an all-locked screw construct. This suggests that there is no statistically significant difference in the stability in fixation between the two methods, allowing the surgeon the freedom to choose the appropriate screw combination unique to each fracture.
authors.affiliation: The Center for Orthopedic Research and Education Institute, Sun Health Research Institute, Sun City West, AZ 85375, USA. chrisestes88@hotmail.com
authors.forename: Chris
authors.initials: C
authors.lastname: Estes
authors.forename: Peter
authors.initials: P
authors.lastname: Rhee
authors.forename: M Wade
authors.initials: MW
authors.lastname: Shrader
authors.forename: Kristine
authors.initials: K
authors.lastname: Csavina
authors.forename: Marc C
authors.initials: MC
authors.lastname: Jacofsky
authors.forename: David J
authors.initials: DJ
authors.lastname: Jacofsky
mesh_terms: D000368:Aged; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D019245:Compressive Strength; D004867:Equipment Design; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D013978:Tibial Fractures / Q000601:surgery*; D016474:Weight-Bearing