Acute Exertional Lateral Compartment Syndrome: A Diagnostic Challenge Presenting With Peroneal Nerve Palsy and Myoglobin-Mediated Acute Kidney Injury-A Case Report.

Background: Acute exertional compartment syndrome (AECS) is a rare but limb-threatening condition that typically occurs in athletes or military recruits in the absence of trauma. Although the anterior compartment of the leg is most commonly affected, isolated lateral compartment involvement is distinctly uncommon. Delayed recognition is frequent and may result in serious complications, including acute kidney injury (AKI) and amputation. Case Presentation: We report the case of a 37-year-old previously healthy man who presented with severe lateral leg pain, progressive swelling and acute foot drop approximately 12 h after a high-intensity interval training (HIIT) session. Initial investigations revealed markedly elevated creatine phosphokinase, myoglobin and creatinine levels, and he was admitted with a provisional diagnosis of rhabdomyolysis-induced AKI. Despite aggressive intravenous hydration, his biochemical parameters worsened and leg pain intensified. Clinical assessment demonstrated a tense lateral compartment and a diagnosis of acute exertional lateral compartment syndrome was made, and urgent fasciotomy was performed. Postoperatively, pain rapidly improved and renal function normalised over several days. At 2-year follow-up, the patient had residual weakness of ankle dorsiflexion (MRC Grade 4) but had returned to moderate physical activity. Conclusion: Acute exertional lateral compartment syndrome is an exceptionally rare diagnosis and may present atypically, leading to delayed treatment. Clinicians should maintain a high index of suspicion in patients presenting with severe leg pain and neurological deficit following exercise. Early diagnosis and prompt fasciotomy remain critical to optimising functional outcomes.