The purpose of this study was to identify factors
that predict implant cut-out after cephalomedullary nailing of intertrochanteric
and subtrochanteric hip fractures, and to test the significance
of calcar referenced tip-apex distance (CalTAD) as a predictor for
cut-out. We retrospectively reviewed 170 consecutive fractures that had
undergone cephalomedullary nailing. Of these, 77 met the inclusion
criteria of a non-pathological fracture with a minimum of 80 days
radiological follow-up (mean 408 days; 81 days to 4.9 years). The
overall cut-out rate was 13% (10/77). The significant parameters in the univariate analysis were tip-apex
distance (TAD) (p <
0.001), CalTAD (p = 0.001), cervical angle
difference (p = 0.004), and lag screw placement in the anteroposterior
(AP) view (Parker’s ratio index) (p = 0.003). Non-significant parameters
were age (p = 0.325), gender (p = 1.000), fracture side (p = 0.507),
fracture type (AO classification) (p = 0.381), Singh Osteoporosis
Index (p = 0.575), lag screw placement in the lateral view (p =
0.123), and reduction quality (modified Baumgaertner’s method) (p = 0.575).
In the multivariate analysis, CalTAD was the only significant measurement
(p = 0.001). CalTAD had almost perfect inter-observer reliability
(interclass correlation coefficient (ICC) 0.901). Our data provide the first reported clinical evidence that CalTAD
is a predictor of cut-out. The finding of CalTAD as the only significant
parameter in the multivariate analysis, along with the univariate
significance of Parker’s ratio index in the AP view, suggest that
inferior placement of the lag screw is preferable to reduce the
rate of cut-out. Cite this article:
