Impact of fracture patterns and patient factors on distal interlocking screw backout after retrograde femoral nailing

Table 1 Patient demographics, n (%)/mean (interquartile range)

Variable	No backout (n = 67)	Backout (n = 9)	P value
Diabetes			0.12
No	59 (88)	6 (67)
Yes	8 (12)	3 (33)
Smoker			0.6
No	56 (84)	7 (78)
Yes	11 (16)	2 (22)
Age (years)	38 (26-61)	68 (62-70)	0.011
Body mass index	27 (24-36)	28 (26-34)	0.4
Gender			> 0.9
Female	34 (51)	5 (56)
Male	33 (49)	4 (44)

Table 2 Distal interlocking screw backout rate, n (%)/mean (interquartile range)

Variable	No backout (n = 67)	Backout (n = 9)	P value
Fracture distance from joint line (mm)
Lateral measurement	120 (63-180)	76 (54-98)	0.052
Anterior-posterior measurement	123 (61-181)	63 (56-80)	0.064
Laterality			0.7
Left	38 (57)	6 (67)
Right	29 (43)	3 (33)