Ischiofemoral impingement syndrome MRI findings and effect of pelvic morphology

Ischiofemoral impingement (IFI) is a clinical entity characterized by hip and buttock pain and caused by narrowing of the space between the lesser trochanter of femur and the ischial tuberosity as well as pathological changes in the quadratus femoris (QF) muscle. IFI is frequently observed in women and the fact that IFI is more common in women suggests that pelvic morphologic changes might be predisposing to IFI. However, relevance of these variations is unclear. The purpose of this study was to evaluate pelvic morphological changes which might be predisposing to IFI. All cases (n=115) who had hip MRI exams between August 2016 and October 2017 in Akdeniz University School of Medicine Department of Radiology were retrospectively evaluated. Sixty-seven cases with history of pelvic surgery or trauma, inflammatory or infectious diseases affecting the pelvis were excluded. Ninety-six hip MRI scans of the remaining 48 patients were retrospectively evaluated for signal changes in QF muscle (edema, fatty atrophy or tear in QF). Those with signal changes were included in the study group whereas those without were included in the control group. Ischiofemoral space (IFS), quadratus femoris space (QFS), femur inclination angle, ischial angle, femoral neck angle (FNA), femoral neck version (FNV), intertuberous distance (ITD) and knee angle (KA) were measured in both groups. IFS and QFS mean values were smaller in the study group (p<0,0001), whereas FNA, FNV, inclination angle and ischial angle mean values were larger in the study group (p values <0,005). However, ITD mean values were not significantly different between study and control groups (p=0,808). The results of our study suggest narrow IFS, QFS and wide FNA, FNV, femur inclination angle or ischial angle might be the morphological factors predisposing to IFI. If any one of these morphologic features is present, pathological signal changes in the QF muscle must be carefully evaluated for IFI.