Subchondral stress fracture of the femoral head (SSFFH) in young and healthy military recruits: clinical recommendations and fracture configurations on MRI.

PURPOSE

This study aimed to evaluate the clinical and radiologic characteristics of the fatigue-type of SSFFH in healthy military recruits.

MATERIALS AND METHOD

We retrospectively analyzed 39 hips from 32 patients who were treated for SSFFH between 2014 and 2018. Clinical variables were analyzed. We devised a categorization system that divided SSFFH into five types (A-E) according to the extent of the fracture line MRI axial view. The femoral head was divided into three parts for the categorization: the anterior third, middle third, and posterior third.

RESULTS

The included patients were 39 hips from 32 patients with the mean age 22.3 years. Almost all patients with SSFFH (96.9%) complained of hip pain with limping at the time of diagnosis. The mean time to the onset of the hip pain from the beginning of military training was 24.8 days. There were seven patients (21.9%) with concomitant stress fractures on whole-body bone scan. Six hips (15.4%) developed osteoarthritis and required surgery. Almost all the cases (94.9%) involved the anterior compartment of the femoral head.

CONCLUSIONS

Military recruits with the hip pain and limping within one month of military training should undergo detailed evaluation. A whole-body bone scan with SPECT is useful for identifying other concomitant stress fractures. Majority of SSFFH involved the anterior compartment of the femoral head.