The holding strength of cannulated screws compared with solid core screws in cortical and cancellous bone

Robert Leggon, R. W. Lindsey, B. J. Doherty, J. Alexander, P. Noble

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

The comparative holding strength of cannulated screws (CS) versus solid core screws (SCS) has not been reported, although differences exist in the respective diameters of their outer thread and pilot drill holes. Our objectives were to characterize these differences and determine the holding power of CS compared with SCS in cortical and cancellous bone. The dimensions of the Synthes (Paoli, PA) 3.5-mm SCS, 3.5-mm CS, 6.5-mm SCS, and 7.0-mm CS were measured, and the cross-sectional area for thread purchase was calculated. Using adult canine femurs, small-fragment 3.5-mm SCS were inserted in cortical (midshaft) and cancellous (condyle) bone of one limb, and CS were placed in similar locations in the contralateral limb. The same technique was used for large-fragment CS and SCS. Pull-out testing was performed using an MTS machine (MTS Systems, Minneapolis, MN) with axial loads applied at 5 mm/s, and data were analyzed to determine the effects of screw type, location, and size. Differences in CS versus SCS design result in higher cross-sectional areas available for SCS thread purchase. Yet no significant differences exists between screw types (SCS vs. CS) in either cortical or cancellous bone. In cancellous bone, large-fragment screws required more force to pull out than did small screws (p = 0.000). The mean force required to pull out small-fragment screws was higher in cortical bone than in cancellous bone (p = 0.000). These data suggest that the clinical decision to use CS versus SCS should not be based on pull-out strength.

Original languageEnglish (US)
Pages (from-to)450-457
Number of pages8
JournalJournal of orthopaedic trauma
Volume7
Issue number5
DOIs
StatePublished - Oct 1993
Externally publishedYes

Keywords

  • Cancellous bone
  • Cannulated screw versus solid core screw
  • Cortical bone

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine

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