The Relationship Between Sacral Slope and Symptomatic Isthmic Spondylolysis in a Cohort of High School Athletes: A Retrospective Analysis.

BACKGROUND: Spondylolysis with and without anterolisthesis is the most common cause of structural back pain in children and adolescents, but few predictive factors have been confirmed. An association between abnormal sacropelvic orientation and both spondylolysis and spondylolisthesis has been supported in the literature. Sacral slope and other sacropelvic measurements are easily accessible variables that could aid clinicians in assessing active adolescents with low back pain, particularly when the diagnosis of spondylolysis is suspected.

OBJECTIVE: To examine the relationship between sacral slope and symptomatic spondylolysis in a cohort of active adolescents.

DESIGN: Case-control retrospective study.

SETTING: Academic outpatient physiatry practice.

PATIENTS: Seventy-four patients of primarily adolescent age (between 12 and 22 years old) with a chief complaint of low back pain and presence of lateral radiographs of the lumbar spine were enrolled. Cases (n = 37) were defined as subjects with evidence of spondylolysis on both radiograph and magnetic resonance imaging of the lumbar spine. Controls (n = 37) were defined as subjects without spondylolysis.

METHODS: Using a single sagittal radiograph, taken with the patient standing, a fellowship-trained interventional spine physiatrist measured the sacral slope of each subject (angle between the superior plate of S1 and a horizontal reference on sagittal imaging of the lumbosacral spine). Ages and genders were collected from medical records.

MAIN OUTCOME MEASUREMENTS: The primary outcome was mean sacral slope. Mean sacral slope of cases was compared with mean sacral slope of controls with the Student t-test.

RESULTS: Ages ranged from 12 to 22 for both groups, with no significant differences in age between the groups (cases: 16.8 ± 2.3 years; controls: 17.7 ± 2.7 years). The patients with spondylolysis (cases) consisted of 29 male and 8 female patients, whereas those without spondylolysis (controls) consisted of 15 male and 21 female patients (gender details for 1 patient were not available). The mean sacral slope among cases was 42.4°, whereas the mean sacral slope among controls was 37.4°. The difference achieved significance (P = .014).

CONCLUSIONS: The interdependence of positional parameters, such as sacral slope, with anatomic parameters, such as pelvic incidence, can affect lumbar lordosis and therefore upright positioning and loading of the spine. Sacral slope may be an important variable for clinicians to consider when caring for young athletes with low back pain, particularly when the index of suspicion for spondylolysis is high.

LEVEL OF EVIDENCE: IV.