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Table 2 Changes in rotational strength by inserting a conventional- or helical blade-type hip screw into a polyurethane bone model, with 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 CW rotation CCW rotation
Average (min–max) (N) p value Average (min–max) (N) p value
5 C1 C2 20.23 (17–23)b   9.35 (8–11)b  
5 C1 ROH2 87.24 (66–103)a < 0.001 76.19 (71–80)a < 0.001
5 C1 RXH2 90.08 (68–105)a   75.66 (65–89)a  
5 H1 H2 93.82 (82–105)a   84.39 (68–102)a  
5 H1 ROC2 15.69 (11–21)c < 0.001 6.27 (5–8)b < 0.001
5 H1 RXC2 18.69 (16–20)b   6.07 (6–6)b  
10 C1 C2 46.09 (41–54)c   28.73 (25–33)c  
10 C1 ROH2 117.53 (72–160)b < 0.001 120.85 (88–153)b < 0.001
10 C1 RXH2 146.90 (104–178)a   147.6 (123–163)a  
10 H1 H2 120.84 (92–147)a   120.05 (80–153)a  
10 H1 ROC2 27.03 (19–35)c < 0.001 22.8 (22–23)c < 0.001
10 H1 RXC2 31.61 (26–42)b   26.34 (24–28)b  
15 C1 C2 89.52 (45–129)b   65.83 (59–75)b  
15 C1 ROH2 174.30 (116–232)a < 0.001 195.66 (153–219)a < 0.001
15 C1 RXH2 183.82 (145–208)a   204.12 (152–261)a  
15 H1 H2 214.62 (157–267)a   196.6 (172–224)a  
15 H1 ROC2 67.17 (61–71)b < 0.001 58.13 (57–60)c < 0.001
15 H1 RXC2 71.49 (63–82)b   62.97 (52–71)b  
  1. 1, leading screw; 2, following screw; C, conventional-type screw; CCW counterclockwise; CW clockwise; H helical blade-type screw; RO, following screw insertion after reaming; RX, following screw insertion without reaming; BMD bone model density