Pelvic fracture instability-associated L5 transverse process fracture, fact or myth? A systematic review and meta-analysis

Hazem Nasef, Ahmed Elhessy, Faris Abushaban, Abduljabbar Alhammoud

Stable or unstable pelvic ring fractures are sometimes associated with L5 transverse process (TP) fractures. This review aimed to determine the effect of L5 TP fractures on pelvic ring fracture stability. We searched electronic databases (including MEDLINE, Google Scholar, and SCOPUS) and performed hand searching of English orthopedics journals and conference abstracts until May 2017. We pooled data from five studies, with a total of 278 patients. Of 28 studies, five were included (four studies involved adult patients, one pediatric population). Of the 278 pelvic fractures (average age 37.33 years; male 132 and female 92), 99 (35.6%) were stable and 179 (64.4%) were unstable (fracture B and C, according to the Tile classification). Sixty-seven (24.1%) were cases with L5 TP, and 211 (75.9%) were cases without L5 TP fracture. The typical causes of injury were road traffic accident (59.2%), fall from height (23.6%), and crush injuries and injuries by heavy objects (17.2%). The pooled odds ratio (OR) of L5 TP between the stable and unstable groups calculated with random effect analysis was 0.418 (0.083-2.108; p = 0.291); after excluding the study on a pediatric population, the pooled OR was 0.349 (0.056-2.159; p = 0.258). L5 TP fractures may indicate high-energy trauma; however, no relationship between L5 TP fractures and pelvic ring fracture stability exists. Prognostic Level IV.