A sacral insufficiency fracture (SIF) often manifests as low back pain or sciatica in the absence of any antecedent trauma. These fractures may be missed because of lack of appropriate imaging. The purpose of this study was to clarify the incidence and clinical features of SIF as well as the characteristic findings on magnetic resonance imaging (MRI) of the lumbar spine.Materials and methods:
The study participants comprised 250 patients (132 male, 118 female; mean age 58.6 years) with pelvic trauma. SIF was identified on computed tomography or MRI. The incidence, initial symptoms, and time delay between the first visit and an accurate diagnosis of SIF were recorded.Results:
We detected 11 cases of SIF. Initial symptoms of SIF were low back pain (36.4%), gluteal pain (63.6%), and coxalgia (18.2%). Two patients complained of both low back pain and gluteal pain. The mean delay between the first visit and an accurate diagnosis of SIF was 23.9 days. This time interval was significantly longer than in patients with other types of pelvic fracture. Four patients underwent MRI targeting the lumbar spine to investigate their symptoms. In all 4 patients, the signal intensity on T1-weighted and fat-suppressed images of the second sacral segment was low and high, respectively.Conclusion:
This study demonstrates that accurate diagnosis of SIF may be delayed because of difficulties in detecting this type of fracture on plain X-ray and the non-specific nature of the presenting complaints. Emergency physicians should keep SIF in mind when investigating patients who complain of low back pain or gluteal pain. Findings at the second sacral segment on MRI targeting the lumbar spine may aid early diagnosis of this type of pelvic fracture.