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

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

BMD	1	2	CW rotation		CCW rotation
BMD	1	2	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, 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

ISSN: 1471-2474