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Multimodal Evaluation of Normal Development of the Ischiofemoral Space from Childhood to Adolescence
Ischiofemoral impingement syndrome has been identified as a potential cause of hip pain in which a narrowing of the space between the ischial tuberosity and lesser trochanter results in injury to the quadratus femoris muscle \cite{Taneja_2013}. This condition is thought to be under-recognized clinically due to atypical presentation with referred pain and a lack of familiarity with physical examination tests for this condition . As specific therapies may be useful in management of ischiofemoral impingement syndrome, improving the detection rate of this entity is essential \cite{Gollwitzer_2017}. MRI is presently the only means of reliably diagnosing this condition in identifying abnormal signal within the quadratus femoris muscle \cite{Hernando2016}. Imaging has also identified predisposing anatomical factors thought to contribute to the development of ischiofemoral impingement syndrome. Specifically, narrowing of the ischiofemoral and quadratus femoris spaces have been implicated in ischiofemoral impingement syndrome \cite{Singer2015}. Studies of asymptomatic adults have reported normal values of these spaces on MRI and observed decreasing values with age with similar findings noted in one CT study \cite{Mara_zdemir_2015,Hujazi_2016,Singer_2015}. It is worth noting despite these measures, quadratus femoris muscle edema has been observed in up to 9% of asymptomatic individuals \cite{Ă–zdemir2015}.
Currently, imaging findings of ischiofemoral impingement syndrome in children have only been reported in a few case reports and one small case-control study \cite{Ali2011,Stenhouse_2016}. It is posited that, over the course of normal development, the ischiofemoral space will change, although there are no reliable normative values across childhood. In addition, the presence of asymptomatic quadratus femoris muscle edema noted in some asymptomatic adults has not been ascertained in the pediatric population. This study aims to leverage previously obtained MRI and CT imaging studies in children without hip pain across the age spectrum to report normative values that may be helpful in understanding hip development in children. In addition, this work will ascertain whether quadratus femoris muscle edema can be found in asymptomatic children on MRI and whether this finding corresponds with narrowing of the ischiofemoral and quadratus femoris spaces in the pediatric population.
Inclusion Criteria
Patients between 4 and 21 years of age with existing abdominal and pelvic imaging (CT and MRI) for non-musculoskeletal indications with images inclusive of the ischiofemoral space.
Exclusion Criteria
Regional musculoskeletal complaint within the preceding 3 months of the examination (e.g., hip, leg, groin or lower back pain)
Trauma to the pelvis or femur
Prior hip or femur surgery
Hamstring tendon injury
Inflammatory arthritis
Myositis
Musculoskeletal or metastatic tumor involving bone
Measurements
Ischiofemoral
space - smallest distance between the lateral
cortex of the ischial tuberosity and medial cortex
of the lesser trochanter on axial images
Quadratus femoris space - smallest
space for passage of the quadratus femoris muscle
bordered by the superolateral surface of the hamstring
tendons and the posteromedial surface of
lesser trochanter on axial
images
Inclination angle (femoral neck-shaft angle) - the
angle between the long axis of the femoral neck
and the long axis of the femoral shaft on coronal
images
Ischial angle - angle between the ischium and line drawn between the posterior aspect of the ischial tuberosities
Intertuberous distance
- largest distance between inner aspects of the bilateral
ischial tuberosities where the hamstring tendons insert
completely to the ischial tuberosities
Quadratus femoris edema score - Grade 0 (none) - intensity is normal; Grade 1 (mild) - focal edema in the region where the
narrowest IFS and QFS values were measured; Grade 2 (moderate) - diffuse edema extending outside the narrowest point of IFS and QFS but within the muscle; Grade 3 (severe) - edema extending to surrounding soft tissues
Other variables
Age
Sex
Weight
Height