Acute atraumatic compartment syndrome of the foot.

Acute atraumatic compartment syndrome (AACS) of the foot is an uncommon, limb-threatening condition that is frequently underrecognized due to its atypical presentation and the absence of high-energy trauma. We report a case of a 32-year-old male presenting with abrupt, severe foot pain and swelling 24 h after playing in an indoor park barefoot, with no history of injury. While initial radiographs, CT, and inflammatory markers were unremarkable, physical examination demonstrated pain disproportionate to findings and increased compartmental tension. Magnetic resonance imaging (MRI) was pivotal in the diagnostic workflow, demonstrating severe diffuse enlargement, compartmental expansion, and marked edema of the abductor hallucis muscle. Laboratory evaluation post-MRI confirmed elevated creatine kinase levels consistent with rhabdomyolysis. These characteristic imaging findings prompted emergent decompressive fasciotomy, which revealed a tense medial compartment and pale musculature that successfully reperfused upon fascial release. Following surgery and aggressive hydration, the patient achieved a full recovery with preserved renal function and limb salvage. This case emphasizes that in the setting of atraumatic foot pain, MRI can provide decisive diagnostic evidence of AACS, assisting in timely surgical intervention and preventing irreversible myonecrosis or permanent neurological deficits.