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 3 Pullout and rotational strengths by inserting a conventional- or helical blade-type hip screw into a polyurethane bone model, with the leading (original) screw

BMD	Original C	Original H	p value
	Pullout
	Average (min–max) (N)	Average (min–max) (N)
5	253.36 (225.9–280.1)	146.15 (114.9–162.7)	< 0.001
10	575.76 (504.7–669.1)	322.81 (257.0–374.2)	< 0.001
15	1261.33 (1078.0–1497.5)	870.87 (784.1–957.7)	0.031
	CW rotation
	Average (min–max) (N)	Average (min–max) (N)
5	41.39 (35.5–46.1)	99.73 (91.9–110.0)	< 0.001
10	98.47 (82.8–116.6)	154.02 (132.2–174.3)	< 0.001
15	167.93 (143.4–188.8)	244.74 (197.7–300.4)	< 0.001
	CCW rotation
	Average (min–max) (N)	Average (min–max) (N)
5	17.68 (16.2–19.3)	85.42 (75.1–95.4)	< 0.001
10	57.68 (38.9–72.1)	147.6 (123.0–163.2)	< 0.001
15	111.27 (82.1–157.5)	211.49 (118.2–272.7)	< 0.001

BMD bone model density; CCW counterclockwise strength; CW clockwise strength; C conventional-type screw; H helical blade-type screw

ISSN: 1471-2474