Ischiofemoral impingement syndrome: an entity with hip pain and abnormalities of the quadratus femoris muscle.
OBJECTIVE
The purpose of this study was to describe the MRI findings of an entity in which patients present with hip pain, abnormal MR signal intensity of the quadratus femoris muscle, and narrowing of the ischiofemoral space.


METHODS
We reviewed MR images of 12 hips in nine patients with hip pain and abnormal MR signal intensity of the quadratus femoris muscle. Using axial MR images, two musculoskeletal radiologists measured the ischiofemoral and quadratus femoris spaces. We also examined changes to muscles and tendons for the presence of edema and tears. Data were compared with 11 hips in 10 control subjects. Statistical analyses determined interobserver variability and differences between groups.


RESULTS
Subjects with an abnormal quadratus femoris muscle were all women 30-71 years old (mean age, 53 years) and had significantly narrower ischiofemoral spaces when compared with control subjects (13 +/- 5 vs 23 +/- 8 mm, respectively; p = 0.002). The quadratus femoris space was significantly narrower in affected subjects (7 +/- 3 vs 12 +/- 4 mm; p = 0.002). Abnormalities of the quadratus femoris muscle included edema (100%), partial tear (33%), and fatty infiltration (8%). The hamstring tendons of affected subjects showed evidence of edema (50%) and partial tears (25%).


CONCLUSIONS
Ischiofemoral impingement may represent a cause of hip pain and should be considered in cases with MR signal abnormality of quadratus femoris muscle.
Torriani
Martin
M
Division of Musculoskeletal Radiology, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., YAW 6048, Boston, MA 02114, USA. mtorriani@hms.harvard.edu
Souto
Silvio C L
SC
Thomas
Bijoy J
BJ
Ouellette
Hugue
H
Bredella
Miriam A
MA
D000328:Adult; D000368:Aged; D018771:Arthralgia / Q000175:diagnosis*; D005260:Female; D005269:Femur / Q000473:pathology*; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D007512:Ischium / Q000473:pathology*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009135:Muscular Diseases / Q000175:diagnosis*; D013577:Syndrome