Quantitative assessment of the ischiofemoral space and evidence of degenerative changes in the quadratus femoris muscle

Injuries to the quadratus femoris (QF) muscle have only recently appeared in the medical literature with the increasing use of advanced imaging in assessing musculoskeletal complaints in the gluteal region. Both strains of the QF muscle and impingement of the QF muscle within the ischiofemoral (IF) space can appear similar on imaging, and normative data of the IF space is important in establishing guidelines for defining these conditions. One purpose of this study was to quantitatively describe the IF and QF spaces. The second goal of this paper was to describe gross abnormalities seen in the QF muscle, and determine if the appearance of the muscle is associated with pelvimetric measurements. Quantitative measurements were taken of the IF and QF spaces on 16 cadavers (29 hips). The QF muscle was then examined and assigned a quantitative grade. The mean IF space was 23.5 +/- A 4.7 mm and QF space was 20.4 +/- A 5.6 mm. Abnormalities of the QF muscle were observed in 51.7 % of the hips, and were associated with a greater approximation when moving the hip from neutral to maximally extended-adducted. While degenerative changes were present in the majority of QF muscles, these changes were not associated with the size of the IF or QF space. However, there was a significant association between the degree of degenerative change observed and (1) an increased approximation of the QF attachments sites; and (2) a narrower intertuberous diameter.