Novel Physical Examination Tests for the Diagnosis of Chronic Sacroiliac Joint Dysfunction and Differentiate It From Lumbar Disc Herniation

Background: Traditional sacroiliac joint (SIJ) provocation tests have been used to diagnose SIJ pain. However, this can simply be changed to chronic SIJ dysfunction (cSIJD) manifests as mechanical changes in the pelvis and lower extremities in addition to pain. A novel composite of physical examinations based on the iliac pronation, pubic tubercle tenderness, and plantar fascia tenderness tests (IPP triple tests) was designed for the diagnosis of cSIJD. Objectives: To evaluate IPP triple tests in the diagnosis of cSIJD and differential diagnosis from lumbar disc herniation (LDH) in comparison with traditional provocation tests. Study Design: Prospective single-blind controlled study. Setting: This study was conducted at the Department of Spine and Spinal Cord Surgery of China Rehabilitation Research Center in Beijing, China. Methods: One hundred and sixty-six patients were assigned into the cSIJD group, LDH group, or healthy control group. The cSIJD diagnosis was confirmed by SIJ injection. The diagnosis of LDH was confirmed according to the 2014 North American Spine Association diagnosis and treatment guidelines for LDH. All patients were examined with IPP triple tests and traditional provocation tests. The sensitivity, specificity, positive and negative likelihood ratios, and areas under the curve (AUCs) were used to evaluate the diagnostic accuracy of the composites or single of the IPP triple tests, and traditional provocation tests. The Delong's test was used for the comparison among AUCs. The kappa analysis was used for the IPP triple tests and traditional provocation tests compared with the reference standard (REF). The independent t test and chi-square test were used to analyze the influence factors (i.e., age, gender), and group on diagnostic accuracy. Results: There was no statistical difference in gender (chi 2 = 0.282, P = 0.596) and age (F = 0.096, P = 0.757) between the 3 groups. The AUC of the iliac pronation test was 0.903 when it was used alone; the AUC of the novel composites of the IPP triple tests was 0.868 (95% confidence interval [CI] = 0.802-0.919); and the diagnostic accuracy of the traditional provocation test was relatively low (AUC = 0.597, 95% CI = 0.512-0.678). The diagnostic accuracy of the IPP triple tests was higher than that of the traditional provocation test, P < 0.05. Kappa consistency comparison showed that the kappa value between the IPP triple tests and the REF was 0.229, the kappa between the traditional provocation test and the REF was 0.052. The age of the patients with inaccurate diagnosis was higher than that of the patients with accurate diagnosis in both methods (traditional tests, P = 0.599; IPP:P= 0.553). Different types of diseases (groups) affect the accuracy of diagnosis, the proportion of inaccuracy of traditional provocation tests was higher than that of the IPP triple tests (77.8% vs 23.6%) in cSIJD, while the 2 methods have high differential diagnostic accuracy in LDH (96.77%) and control groups (97.56%). Limitations: Small size of LDH patients and differences in physical tests among examiners. Conclusions: The novel composites of IPP triple tests have higher accuracy than the traditional provocation tests in diagnosing cSIJD and both have good accuracy in differentiating cSIJD from LDH. IPP triple tests may be an alternative physical examination for clinical screening of cSIJD.