Table 1.

Overview of various risk factors and the respective odds ratio, its 95 % confidence interval and statistical significance

Risk factor	Odd’s ratio	95 % CI of odds ratio	p-value
Fracture type A1	0.3	0.1–1.0	0.04 a
Fracture type A2	3.3	1.1–10.0	0.03 a
Fracture type A3	0.7	0.2–3.1	0.68 a
Tip–apex distance > 20 mm	1.9	0.7–5.3	0.22 a
Lag screw positioned in anterior or posterior third of femoral head	5.5	0.5–65.0	0.19 b
Lag screw positioned in cranial third of the femoral head	2.5	0.5–13.4	0.28 b
Angle deviation between femoral neck axis and lag screw > 10°	6.5	1.8–23.9	0.005 b
Gliding distance of telescrew ≤15 mm	4.2	1.2–14.3	0.024 b
Displacement >5 mm	1.5	0.5–4.8	0.46 a
AR-Pin too short	7.7	0.76–79.1	0.082 b
AR pin too long	8.8	1.6–48.1	0.009 b
AR pin too short or too long	10.8	2.6–46.0	0.001 b

Reference for the odds ratios were all cases without the respective risk factor. In the biaxial fixation system AR pin length seemed to have the greatest association with cut-out and cut-through

^a Chi squared test

^b Fisher’s exact test