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.