Is there a change in ischiofemoral space in lateral position in comparison to supine

Ischiofemoral impingement (IFI) is caused due to impingement of soft tissues between the ischium and the lesser trochanter of the femur, resulting in pain and discomfort. IFI can be caused due to anatomical abnormality, previous trauma and surgery. The quadratus femoris muscle is usually affected in these cases, which can become oedematous and show fatty atrophy. Management of IFI include analgesics, physiotherapy, image-guided intervention and surgery. This study aims to provide an overview of IFI, evaluate the ischiofemoral space in a cohort of ten patients, and suggest the safest position for image-guided interventions in patients with IFI. The ischiofemoral space and distance between the sciatic nerve and the medial part of the femoral neck were measured in supine and lateral positions on 10 consecutive patients by two fellowship-trained musculoskeletal radiologists on Computed Tomography (CT) axial sequence. There were 10 patients in the study (3 female and 7 males), with an average age of 29 years (11-70 years). A statistically significant increase in the ischiofemoral space and the distance between the sciatic nerve and the medial part of the femoral neck was found in the lateral position compared to the supine position. There was good intra- and inter-observer reliability, with a kappa value of 0.8. The increase in the ischiofemoral interval in the lateral position suggests that it is relatively safer to perform image-guided interventions and injections in the ischiofemoral interval in the lateral position with a potential reduction in the risk of incidental sciatic nerve injury.