Radiographic Prevalence Of Sacroiliac Joint Abnormalities And Clinical Outcomes In Patients With Femoroacetabular Impingement Syndrome

OBJECTIVES: Patients with femoroacetabular impingement syndrome (FAIS) typically present with a gradual onset of groin pain. They may also presentwith gluteal pain, which can be related to posterior acetabular impingement or posterior joint degeneration secondary to FAIS or more commonly aberrant gait mechanics secondary to abnormal hip morphology. Gluteal pain is also a common presenting symptom in patients with sacroiliac joint (SIJ) problems. The date, the literature on the correlation between SIJ pathology and FAIS has been limited. As such, the purpose of the current study id to quantify the prevalenceof SIJ abnormalities FAIS patients using imaging modalities and to compare outcomes based on SIJ abnormalities. METHODS: Radiographs, CT and MRI scans of 1,009 consecutive patients who underwent primary hip arthroscopy for FAIS from January 2012 to January 2016 were identified. Exclusion criteria included patients undergoing bilateral or revision surgery, history of dysplasia, and less than two-year follow-up. On radiographs, SIJ joints were graded using modified New York criteria for spondyloarthropathy. CT scans and MRIs were reviewed for joint surface erosions, subchondral sclerosis, joint-space narrowing, pseudo-widening, bone marrow edema, and ankylosis. Patients with SIJ abnormalities were matched 1:2 to patients without SIJ abnormalities by age and BMI. Outcomes included the hip outcome score- activities of daily living (HOS-ADL), sports-subscale (HOS-SS), modified Harris hip score (mHHS), and visual analog scales (VAS) for pain and satisfaction. RESULTS: 743 patients were included; 187 (25.2%) demonstrated SIJ changes. 164 (87.7%) had radiographic changes, 88 (63.3%) on CT, and 125 (66.8%) on MRI. SI changes on any imaging modality were correlated with pain to palpation (PTP) of the SI joint (r=0.11; p=0.004) on physical exam. History of SI pain was correlated with PTP of the SI joint (r=0.21; p<0.001). After matching, patients without SIJ abnormalities had significantly greater HOS-ADL (95.4 vs. 90.6;p=0.001), HOS-SS (91.1 vs. 77.5;p<0.001), and mHHS (91.3 vs. 84.5;p<0.001) scores and significantly less VAS pain (10.9 vs. 25.7;p<0.001) than those with abnormalities. Patients without SIJ abnormalities had greater odds of achieving the MCID for the HOS-ADL (Odds ratio [OR]=2.91, 95%confidence interval [95% CI]=1.5-5.5;p=0.001) and for the HOS-SS (OR=2.83, 95% CI = 1.6-4.9;p<0.001), but not for the mHHS (OR=1.73, 95% CI = 0.93-3.2; p=0.081). CONCLUSION: There is a high prevalence of SIJ abnormalities in patients with FAIS. Patients with abnormalities may expect inferior outcomes and persistent post-operative pain.