Correlation of Ultrasound and MRI Measurements of Quadratus Femoris Thickness and Ischiofemoral Distance in Clinically and Radiologically Diagnosed Ischiofemoral Impingement

Ischiofemoral impingement (IFI) was first described in 1977 by Karl A. Johnson, and his study is widely regarded as the first clinical definition of the syndrome. IFI is defined as an extra-articular hip impingement syndrome resulting from the narrowing of the space between the ischium and the lesser trochanter, leading to compression of the quadratus femoris muscle and surrounding soft tissues, thereby causing clinical symptoms.

IFI findings are associated with edema and irritation of the quadratus femoris muscle, as well as secondary atrophic fatty degeneration in chronic cases. The primary symptom is posterior and lateral hip pain, often exacerbated by physical activity. Due to the close anatomical relationship between the quadratus femoris muscle and the sciatic nerve, irritation of the nerve may lead to pain radiating anteriorly, to the posterior thigh, and distally to the knee.

The etiology of IFI is multifactorial, involving congenital anatomical variations, post-traumatic sequelae, postoperative changes following hip surgery, and primary hip joint pathologies. Additional factors, such as femoral anteversion, acetabular retroversion, and abductor or adductor insufficiencies, may also contribute to its pathogenesis. The exact prevalence of IFI remains unknown, but it has been reported to be more common in females than in males, with a female-to-male ratio of approximately 3:1. This higher incidence in females is attributed to gender differences in pelvic morphology and a narrower ischiofemoral space. While IFI typically affects middle-aged and older adults, it has been observed across a wide age range (30-70 years). Although IFI generally presents unilaterally, bilateral involvement has been reported in 25-40% of cases, with no consensus in the literature regarding side predominance. The diagnosis of IFI requires a combination of detailed patient history, physical examination, and imaging techniques. Clinical tests such as the long-stride walking test and the ischiofemoral impingement test play a significant role in diagnosis, while MRI is considered the gold-standard imaging modality for confirmation.

The present study aims to investigate the correlation between ultrasound measurements and MRI findings in patients diagnosed with IFI through MRI and clinical examination. Specifically, ultrasound measurements of quadratus femoris muscle thickness and ischiofemoral distance will be evaluated for their consistency with MRI findings. Additionally, clinical parameters related to IFI will be assessed to explore their association with imaging results. The primary objective of this study is to determine the feasibility of using ultrasound, a more cost-effective imaging method, as an alternative diagnostic tool for IFI. The hypothesis is that by establishing a reliable correlation between ultrasound and MRI findings, it may be possible to implement a lower-cost and more accessible diagnostic approach for this condition.