title: Drilling the near cortex with elongated figure-of-8 holes to reduce the stiffness of a locking compression plate construct.
abstract: OBJECTIVE
  To compare the stiffness of locking compression plate (LCP) constructs with or without drilling the near cortex with elongated figure-of-8 holes.
  
  
  METHODS
  24 synthetic bones were sawn to create a 10-mm gap and were fixed with a 9-hole 4.5-mm narrow LCP. In 12 bones, the near cortex of the adjacent holes to the LCP holes was drilled to create elongated figure-of-8 holes before screw insertion. The stiffness of LCP constructs under axial loading or 4-point bending was assessed by (1) dynamic quasi-physiological testing for fatigue strength, (2) quasi-static testing for stiffness, and (3) testing for absolute strength to failure.
  
  
  RESULTS
  None of the 24 constructs had subcatastrophic or catastrophic failure after 10 000 cycles of fatigue loading (p=1.000). The axial stiffness reduced by 16% from 613±62 to 517±44 N/mm (p=0.012) in the case group, whereas the bending stiffness was 16±1 Nm2 in both groups (p=1.000). The maximum axial load to catastrophic failure was 1596±84 N for the control group and 1627±48 N for the case group (p=0.486), whereas the maximum bending moment to catastrophic failure was 79±12 and 80±10 Nm, respectively (p=0.919).
  
  
  CONCLUSIONS
  Drilling the near cortex with elongated figure-of-8 holes reduces the axial stiffness of the LCP construct, without compromising its bending stiffness or strength.
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: Jerry Yongqiang
authors.initials: JY
authors.lastname: Chen
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: Benjamin Fu Hong
authors.initials: BF
authors.lastname: Ang
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: Andy Khye Soon
authors.initials: AK
authors.lastname: Yew
authors.affiliation: Nanyang Technological University, Singapore.
authors.forename: Siaw Meng
authors.initials: SM
authors.lastname: Chou
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: Shi-Lu
authors.initials: SL
authors.lastname: Chia
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: Joyce Suang Bee
authors.initials: JS
authors.lastname: Koh
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: Tet Sen
authors.initials: TS
authors.lastname: Howe
mesh_terms: D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D019245:Compressive Strength; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D008422:Materials Testing; D008954:Models, Biological; D016474:Weight-Bearing
keywords: bone plates; compressive strength; fracture fixation