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

Abstract

Purpose: To test the significance of calcar referenced tip-apex distance (CalTAD) and the length of anti-rotation screw (AR screw) as predictors for failure after biaxial cephalomedullary (CM) nailing of intertrochanteric fractures. Methods: We retrospectively reviewed 190 consecutive fractures that had undergone biaxial CM nailing. Of these, 67 met the inclusion criteria of a non-pathological fracture with a minimum of 90 days radiological follow-up (mean 458 days; 91 days to 4.9 years). Results: The overall failure rate was 15% (10 of 67). Failure was associated with a higher CalTAD in most of the patients (13%, p < 0.001). A higher tip-apex distance (TAD) was not significantly associated with failure (p = 0.132), when the CalTAD was less than 25 mm. When the AR screw length exceeded a line connecting the tip of the nail and the lag screw, screw cutout occurred only in one patient (p = 0.095). Conclusion: Our data provide the first reported clinical evidence that the CalTAD is a better predictor of cutout in biaxial CM nailing than TAD measurement. However, the length of anti-rotational element does not seem to be an independent predictor of CM nailing failure.