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Table 1 Changes in pullout strength by inserting a conventional- or helical blade-type hip screw into a polyurethane bone model of different bone densities, with the types of the leading and following screws kept the same or alternated

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

BMD

1

2

Pullout

p value

Average (min–max) (N)

5

C1

C2

174.55 (138–207)a

 

5

C1

ROH2

107.03 (96–120)b

< 0.001

5

C1

RXH2

111.56 (90–135)b

 

5

H1

H2

128.85 (106–148)b

 

5

H1

ROC2

158.97 (135–194)a

< 0.001

5

H1

RXC2

160.36 (101–222)a

 

10

C1

C2

445.64 (348–552)a

 

10

C1

ROH2

285.17 (256–314)b

< 0.001

10

C1

RXH2

272.63 (253–290)c

 

10

H1

H2

318.17 (279–382)b

 

10

H1

ROC2

338.81 (284–382)a

< 0.001

10

H1

RXC2

351.22 (299–395)a

 

15

C1

C2

914.53 (665–1106)a

 

15

C1

ROH2

636.36 (507–726)b

< 0.001

15

C1

RXH2

626.09 (536–733)b

 

15

H1

H2

833.24 (777–892)b

 

15

H1

ROC2

868.54 (727–966)a

< 0.001

15

H1

RXC2

879.78 (744–1004)a

 
  1. 1, leading screw; 2, following screw; C, conventional-type screw; H, helical blade-type screw RO, following screw insertion after reaming; RX, following screw insertion without reaming; BMD bone model density