MRI measurement assessment on ischiofemoral impingement syndrome

To explore the value of MRI upon diagnosis of ischiofemoral impingement syndrome (IFI) and to recognise deformation or oedema of the quadratus femoris muscle. MRI applied to measure the ischial femoral space (IFS), the average width of quadratus femoral space (QFS), and the ischial intertuberal diameter.

A retrospective analysis was carried out of 213 hip joints MRI images of 58 cases diagnosed with IFI and 61 cases of normal subjects. IFS, QFS and ischial intertuberal diameter were measured by axial T1WI sequence. The morphological and signal changes of the quadratus femoris muscle were observed through proton density weighted image fat suppression sequence (PDWI-FS).

The widths of IFS and QFS in the normal group were larger than those in the case group, while the ischial intertuberal diameter was significantly smaller (p < 0.05). Pearson correlation analysis revealed that there was a positive correlation (r = 0.824) between IFS and QFS in all hip joints and a negative correlation between the ischial intertuberal diameter and the widths of IFS and QFS (r = -0.213, -0.222, p < 0.05) respectively. As the grade of oedema in quadratus femoris muscle increased, the corresponding IFS gradually decreased. The corresponding IFS width of grade 0 oedema of the quadratus femoris muscle oedema was significantly higher than that of grade 1, grade 2 and grade 3. The receiver operating characteristic curve (ROC) of the subjects was applied to determine the diagnostic boundary value of the IFS and QFS in IFI patients, which was 1.98 cm and 1.05 cm respectively. The area under the curve (AUC) was 0.948 and 0.953 respectively.

MRI examination could provide a reliable basis for the diagnosis of ischiofemoral impingement syndrome. The narrowing of IFS and QFS with deformation and oedema in the quadratus femoris muscle may be the features of manifestation of IFI.