Alex Sun, MD Faculty Advisor: Peter Pham, MD Sensitivity and specificity of sacral arcuate line disruption for fractures on plain radiography Alex Sun, MD Faculty Advisor: Peter Pham, MD

Background Sacral fractures can occur in young adults after high energy trauma and elderly patients in low energy falls Sacral fractures are frequently underdiagnosed Only 49% of sacral fractures are diagnosed on initial hospital visit Patients may go on to develop neurologic deficits due to inadequate treatment Depending on location of fracture neurologic injury is common Symptoms include lower extremity weakness Urinary and rectal dysfunction Sexual dysfunction

Treatment Non-operative management Operative management Non-displaced fractures No neurologic injury Operative management Displaced or unstable fractures Associated pelvic ring disruption Neurologic injury

Imaging Lines represent roof of the anterior sacral foramina and neural grooves Superior three arcs are most common seen Abnormalities of the sacral arcuate lines are indicative of fracture

Imaging Specific findings that indicate SL disruption Line discontinuity Deformity Displacement Density change

Line discontinuity

Deformity Angulation or buckling of lines

Displacement Increased distance between arcs

Density Change Compression or callus formation

Question and Hypothesis How sensitive and specific are the sacral arcuate lines for sacral ala fractures? No study has been conducted to evaluate the sensitivity and specific of SL. Hypothesis: the sacral arcuate lines are both very sensitive and specific for sacral ala fractures

Method Compiled a list of ~300 patients with documented sacral ala fractures seen on CT Each patient must have initial pelvic radiograph Age ranged from 18-98 years old. Pediatric and pregnant patients excluded Insufficiency and pathologic fractures excluded Retrospectively reviewed the initial AP pelvic radiographs. Findings that indicate SL disruption Line discontinuity, displacement, deformity, density change Asymmetry Record percentage of fractures on missed on initial plain film Determine any limitations and confounding factors Such bowel gas, osteopenia, positioning

Results Initial Diagnosis 20% 299 Patients 59 Excluded 186 Positive Radiographs 76% Sensitivity for all ages 84% Sensitivity for 18-50 years old 59 Negative Radiographs

Results

Results

Marginal fractures Minimally displaced Above the sacral lines Can be seen on radiograph but arcuate lines are intact

Conclusion Sacral arcuate line disruption is sensitivity for sacral fractures Particularly 18-50 year old population Evaluation sacral arcuate lines can improve sensitivity for sacral fractures 20% initial diagnosis on radiograph

Future Study Prospective blind study using a list of 50 cases: 10 cases will have sacral +/- pelvic fractures Remaining cases will all have pelvic fractures Recruit attending to review case set MSK attending Future QI project Create primer/lecture to educate residents on specific findings Compare sensitivity before and after primer/lecture.

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