Magnetic resonance arthrography of the hip: Prevalence of diagnoses not suspected by the referring physician and correlation with clinical examination and pain score

Background: Magnetic resonance arthrography (MRA) of the hip is the most sensitive imaging modality for intraarticular pathologies such as labral tears. Purpose: To evaluate the prevalence of non-suspected pathologies revealed by hip MRA and correlate them to physical examination/pain level. Material and Methods: All hip MRAs (2011-2013) were retrospectively evaluated for intra-and extra-articular pathologies in consensus by two readers. A clinical score (0-7)/pain score (0-10) was calculated for each patient based on orthopedic test results extracted from referral forms/a telephone questionnaire. Patients were divided into four groups according to MRA findings: intra-articular expected (targeted) pathology only; intra-articular targeted and additional non-targeted (unexpected) pathology; non-targeted pathology; and no pathology. Pathologies prevalence/ clinical score/pain score were compared between the groups. Results: A total of 229 MRAs were included (127 men, 102 women; mean age, 36.5=14.17 years): 111(48.4%) patients had solely intra-articular targeted pathology. Significant non-targeted pathologies were detected in 76 (33%) patients (targeted and non-targeted, 51; non-targeted only 25). No significant pathology was detected in 42 patients (18%). Mean physical examination score was 2.77=1.77, range 0-7. There was no significant difference or correlation (r=0.017, P=0.804) between the clinical scores of the different MRA pathology groups. Pain score (143 patients) was significantly higher in the non-targeted pathology group compared to the targeted and non-targeted group (P=0.04) and to the no pathology group (P=0.04). There was no correlation between the physical examination score and the pain score (r=0.017, P=0.804). Conclusion: Unsuspected non-targeted pathologies were detected in 33% of hip MRA. Physical examination/pain level could not differentiate between patients.