Staged Management of Delayed-Onset Upper Arm Compartment Syndrome Following Humeral Shaft Fracture: A Case Report.

Background: Acute compartment syndrome (ACS) is a limb-threatening condition associated with high morbidity and a substantial risk of long-term functional impairment. ACS most commonly develops shortly after fractures and typically affects the legs and forearms. Although ACS of the upper arm is rare, accounting for approximately 0.6% of cases, the condition can result in severe complications comparable to those observed in the leg and forearm. Therefore, early recognition and appropriate management are essential to prevent adverse outcomes. Case Presentation: We report the case of a 21-year-old male who developed ACS of the upper arm secondary to a humeral shaft fracture 4 days postinjury. The patient was referred to our hospital on postinjury Day 3 with mild upper arm pain but no neurological deficits. On postinjury Day 4, however, he experienced rapid worsening of swelling and severe pain. ACS was diagnosed based on elevated intracompartmental pressure. Staged management, consisting of emergent fasciotomy and external fixation with negative-pressure wound therapy, followed by definitive fixation, successfully preserved upper arm function. Conclusions: ACS should be considered in all patients after fractures, including those involving uncommon anatomical sites, such as the humerus. Prompt diagnosis and timely surgical intervention are critical to prevent severe complications and preserve muscle function.