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Table 4 Percent reduction of the pullout and rotational strengths of the following screws relevant to those of the original screws of the C- and H-type screws

From: Conventional versus helical blade screw insertion following the removal of the femoral head screw: a biomechanical evaluation using trochanteric gamma 3 locking nail versus PFN antirotation

  C2   H2
  C1-C2 H1-ROC2 H1-RXC2   H1-H2 C1-ROH2 C1-RXH2
  RD (%) p value RD (%) p value RD (%) p value   RD (%) p value RD (%) p value RD (%) p value
  Pullout   Pullout
PCF 5 31.11 < 0.001 37.26 < 0.001 36.71 < 0.001 PCF 5 11.84 < 0.001 26.77 < 0.001 23.67 < 0.001
PCF 10 22.6 < 0.001 41.15 < 0.001 39 < 0.001 PCF 10 1.44 0.358 11.66 < 0.001 15.54 < 0.001
PCF 15 27.5 < 0.001 31.14 < 0.001 30.25 < 0.001 PCF 15 4.32 0.001 26.93 < 0.001 28.11 < 0.001
  Clockwise rotation   Clockwise rotation
PCF 5 51.13* < 0.001 62.10* < 0.001 54.83* < 0.001 PCF 5 5.93   12.52 < 0.001 9.68 < 0.001
PCF 10 53.20* < 0.001 72.55* < 0.001 67.90* < 0.001 PCF 10 21.54   23.69 < 0.001 4.62 0.102
PCF 15 46.69 < 0.001 60.00* < 0.001 57.43* < 0.001 PCF 15 12.31   28.78 < 0.001 24.89 < 0.001
  Counterclockwise rotation   Counterclockwise rotation
PCF 5 47.13 < 0.001 64.52* < 0.001 65.69* < 0.001 PCF 5 1.21 0.564 10.81 < 0.001 11.43 < 0.001
PCF 10 50.19* < 0.001 60.48* < 0.001 54.33* < 0.001 PCF 10 18.67 < 0.001 18.13 < 0.001 1.74 0.441
PCF 15 40.84 < 0.001 47.76 < 0.001 43.41 < 0.001 PCF 15 7.04 0.015 7.48 0.015 3.48 0.218
  1. C conventional-type screw; H helical blade-type screw; RO, following screw insertion after reaming; RX, following screw insertion without reaming; RD, strength reduction rate (%) compared with original screw; PCF pounds per cubic feet
  2. *50% above strength reduction compared with original screw