Predictors of failure for cephalomedullary nailing of proximal femoral fractures

Abstract

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.

Arthroplasty for unstable pertrochanteric hip fractures may offer a lower re-operation rate as compared to cephalomedullary nailing

“…Both biomechanical and clinical data suggest that CM nails have a mechanical advantage over extra-medullary implants in their ability to resist femoral shaft medialization and varus malunion, and this has led to the increased use of CM nails for hip fractures [8][9][10][11]. However, recent studies showed that there is still a high revision rate for unstable hip fractures treated with CM nails mainly due to cut-out of the lag screw [12,13].…”

Is calcar referenced tip-apex distance a better predicting factor for cutting out in biaxial cephalomedullary nails than tip-apex distance?

“…It supports the findings from previous studies that the inferior placement of the lag screw reduces cutout. 7,16,1,18 It provides the first clinical evidence behind the validity of CalTAD as a better predictor of cutout than TAD in biaxial CM. It questions the validity of the length of AR screw as a predictor of failure of biaxial CM nail and suggests further investigations to study its impact on such constructs.…”

“…9 This may be due to a shorter operating time, reduced visible intraoperative blood loss, and improved walking ability in unstable hip fractures associated with CM nail. 1 Current CM concepts may be classified as monoaxial and biaxial. In monoaxial systems, special lag screw designs have been introduced to strengthen rotational stability, whereas in biaxial systems, a second element, an AR screw, is meant to achieve this.…”

“…9,12 A total of three previous studies found high TAD values to be a significant predictor of cutout in CM nails . 1,13,14 Yet more recent studies suggest that the cutout complication is very low even in patients with high TAD, if the lag screw was positioned inferior in the head and neck. 5,15 A biomechanical study by Kuzyk et al 7 found that inferior placement of the lag screw gives the highest axial and torsional stiffness.…”

Common complications in hip fracture surgery: Tips/tricks and solutions to avoid them

“…1). This complication is encountered after fixation with either intramedullary [18,19] or extramedullary devices [20]. Cut out has been associated with the Tip Apex Distance (TAD) Index, which represents the sum of distances measured in mm in both anteroposterior and lateral radiographs from the centre of the femoral head to the top of the lag screw [21].…”