Smaller Ischiofemoral Space Is Associated With Proximal Hamstring Injuries

Purpose To develop a reference ischiofemoral space (IFS) value for patients with proximal hamstring injuries (HSI) and to compare it with individuals without proximal hamstring pathology. Methods We retrospectively collected the data from our institution. Patients aged 18 years or older with a proximal HSI were included. Patients with insufficient imaging data, those with prior hip surgery, those with concurrent femoroacetabular impingement syndrome, and those with concurrent ischiofemoral impingement as defined by quadratus femoris edema on magnetic resonance imaging (MRI) were excluded. A 1:2 matched‐cohort analysis was conducted. Two cohorts were (1) patients with proximal HSI and (2) patients with femoroacetabular impingement syndrome as a control cohort (Control). Both pelvic anteroposterior (AP) radiographs and axial MRI were used to assess IFS and were compared between the 2 cohorts. Additionally, the neck‐shaft angle was collected and compared. Results There were 60 patients in the HSI cohort and 124 patients in the control cohort. The mean neck‐shaft angle, IFS from the AP pelvis, and IFS from the axial MRI for the HSI cohort were 136.35° ± 5.63°, 24.35 ± 8.60 mm, and 26.57 ± 7.96 mm, respectively. For the control cohort, these values were 135.30° ± 4.53°, 29.83 ± 9.84 mm, and 29.28 ± 8.54 mm, respectively. The IFS in the HSI group was significantly lower than that in the control group on both pelvic AP radiograph ( P < .001) and axial MRI ( P = .036). Conclusions Patients with proximal HSI had a smaller IFS compared with those with femoroacetabular impingement syndrome. Level of Evidence Level III, retrospective cohort study.