The L5 transverse process fracture revisited. Does its presence predict the pelvis fracture instability?

BACKGROUND

The presence of a L5 transverse process fracture is reported in many texts to be a marker of pelvis fracture instability. There is paucity of literature to support this view. Only two previous studies have been performed on this subject with statistical analysis.

METHODS

We conducted a retrospective cross-sectional review of all abdominopelvic CT scans performed for blunt abdominal trauma in a Level 1 Trauma Unit between January 2012 and August 2013. A total of 203 patients met our inclusion criteria. Fifty four (54) of these patients had an associated pelvis fracture.

RESULTS

Of the 54 patients with pelvis fractures 26 (48%) had an unstable fracture (AO Type B and C) and 28 (52%) had a stable pelvis fracture (AO Type A). Five (19%) of the 26 patients with an unstable pelvis fracture had an associated L5 transverse process fracture. This association was not statistically significant (P=0.724). Seven (12%) of the 28 patients with a stable fracture pattern had an associated L5 transverse process fracture. Three patients (2%) had an L5 transverse fracture in the absence of a demonstrable pelvis fracture. The relative risk of an unstable pelvis fracture in the presence of a L5 transverse process fracture is 1.2 (CI 0.6 2.3).

CONCLUSIONS

The presence of an L5 transverse process fracture on an abdominopelvic CT scan is strongly associated with an underlying pelvis fracture (P<0.001). Statistically, its presence however does not strongly predict instability (P=0.724). The latter finding differs from the previously published studies.