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

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.