Quadratus femoris muscle: spectrum of MR imaging findings in 51 patients presenting with painful hip

Purpose: To provide an overview of magnetic resonance (MR) imaging findings related to quadratus femoris muscle (QFm) pathologies in symptomatic patients. Material and Methods: MR imaging studies from 51 patients, who were retrospectively recruited within a 2-year period, in 5 health care centers were reviewed. Inclusion criteria included: (i) hip pain; (ii) QFm abnormal signal; (iii) identification of other pathology in the QFm anatomical area. Exclusion criteria included: (i) other symptomatic hip/pelvic pathology; (ii) incomplete MR examination. The presence/location of QFm oedema and configuration of QFm fibers were evaluated and classified. Hamstring tendons were assessed for tendinosis/tear. Ischiofemoral impingement syndrome (IFIs) was indicated by QFm oedema and restriction of ischiofemoral space (IFS)/quadratus femoris space (QFS). QFm tears were categorised as complete/partial/chronic. Fisher’s exact test was used for statistical analysis. Results: IFIs diagnosis, related to various aetiologies, was suggested in 39 patients. The absence of severe QFm oedema and crowded configuration of QFm fibers correlated with IFIs diagnosis (p<0.05). In 18/39 (46.2%) of patients, restriction of the IFS/QFS was due to an underlying pathology. QFm tears were diagnosed in 5 patients. QFm oedema, usually mild, located at the myotendinous junction, was revealed in 4/5 patients. In 7 patients various pathologies related to the QFm were disclosed, which broadly included neoplastic disorders, myositis and bursitis. Conclusions: MR imaging can depict and characterise various QFm pathologies including IFIs, traumatic lesions, myositis and neoplastic disorders.  Detailed analysis of the oedema pattern and the configuration of muscular fibers matched with clinical findings can lead to precise diagnosis.