Published online Sep 16, 2026. doi: 10.12998/wjcc.125200
Revised: August 30, 2026
Accepted: September 17, 2026
Published online: September 16, 2026
Processing time: 80 Days and 0.1 Hours
Subchondral stress fracture of the femoral head (SSFFH) is an uncommon femoral-head injury associated with repetitive mechanical loading and may mimic osteonecrosis of the femoral head (ONFH), particularly when collapse is present. Military personnel represent a clinically relevant population in whom early differentiation is important.
To characterize the clinical and imaging features of SSFFH associated with military training and identify features that help distinguish SSFFH from ONFH, with particular attention to the relationship between structural collapse and clinical status.
We retrospectively reviewed 242 inpatient records of military patients with hip pain or femoral-head injury admitted between June 2013 and June 2019. After exclusion of 68 records, 174 patients (220 hips) were included: 127 patients with SSFFH (139 hips) and 47 patients with ONFH (81 hips). Clinical characteristics, exposure history, laboratory data, radiographs, magnetic resonance imaging (MRI) findings, and SSFFH stage were analyzed. Two experienced musculoskeletal radiologists independently reviewed imaging while blinded to clinical information; disagreements were resolved by consensus. All primary comparative analyses were performed at the patient level, with one index hip per patient for stage-based analyses. Statistical analyses were performed using SPSS version 27.0.
Compared with ONFH, patients with SSFFH were younger [median interquartile range: 20.0 (19.0-21.0) years vs 23.0 (20.5-29.0) years; P < 0.001], had lower body mass index [21.28 (20.07-22.54) kg/m2 vs 23.17 (21.20-25.79) kg/m2; P < 0.001], and more often had unilateral involvement (90.6% vs 27.7%; P < 0.001). Creatine kinase was higher in SSFFH [95.0 (79.0-136.5) U/L vs 87.0 (54.0-109.5) U/L; P = 0.002], whereas total cholesterol was lower (3.86 ± 0.72 mmol/L vs 4.33 ± 1.01 mmol/L; P = 0.004). In multivariable binary logistic regression, bilateral involvement was associated with higher odds of ONFH [adjusted odds ratio (OR) = 21.188, 95%CI: 6.168-72.784; P < 0.001], whereas each increase in training-intensity category was associated with lower odds of ONFH (adjusted OR = 0.120, 95%CI: 0.045-0.319; P < 0.001); alcohol exposure contributed to the model overall (P = 0.019). Across SSFFH Stages I-III, symptom duration, Visual Analog Scale score, Harris Hip Score, range of motion, bone marrow edema, joint effusion, and Tönnis grade differed significantly. These stage comparisons were cross-sectional and do not demonstrate individual longitudinal improvement.
In young military personnel with unilateral femoral-head subchondral abnormalities occurring in the setting of repetitive training and with fewer conventional ONFH risk factors, SSFFH should be considered. MRI is central to recognition and differentiation. In this cohort, femoral head collapse was not consistently associated with greater pain or worse function; therefore, collapse alone may not be sufficient to determine the need for arthroplasty. Treatment should incorporate symptoms, functional impairment, structural damage, treatment response, and longitudinal clinical and imaging findings. All stage-associated differences were cross-sectional observations and do not establish spontaneous lower current symptom burden or a fixed natural history.
Core Tip: This retrospective study compared subchondral stress fracture of the femoral head (SSFFH) with osteonecrosis of the femoral head in military personnel. SSFFH was associated with younger age, lower body mass index, higher training intensity, predominantly unilateral involvement, and less corticosteroid/alcohol exposure. Within SSFFH, Stage II had the greatest pain and functional limitation, whereas Stage III showed more advanced structural changes but lower pain and better function. Because these comparisons were cross-sectional, collapse alone should not automatically determine the need for arthroplasty; treatment should integrate symptoms, function, structural damage, treatment response, and longitudinal findings.