 Introduction/Background Acute onset of limp or refusal to walk is a common complaint in children, accounting for approximately 4% of visits in one pediatric emergency department [1]. The acutely limping child can be a diagnostic dilemma for clinicians. Most commonly, the acute limp is caused by minor trauma or self-limiting benign conditions but can also be caused by limb-threatening or life-threatening etiologies [2-6]. The cause of limp can usually be determined by a careful history and physical examination. The differential diagnosis of limping is broad and depends on the presence of signs of infection, localization of pain, and history of trauma [6]. The differential diagnosis in a limping child also depends on age. This discussion relates to the initial imaging of the ambulatory child under the age of 5 years who presents with an acute onset of a limp. The presence of fever, elevated white blood cell count, elevated erythrocyte sedimentation rate, or elevated C- reactive protein suggests infection. Localization of pathology is based on site of pain, tenderness, presence of erythema, swelling, and positive physical maneuvers and signs, such as the Trendelenburg test, Galeazzi sign, Patrick/FABER test, pelvic compression test, and psoas sign [7]. A detailed analysis of gait can suggest the diagnosis [6]. Discussion of Procedures by Variant Variant 1: Child up to age 5. Acute limp. Nonlocalized symptoms. No concern for infection. Initial imaging. The most common noninfectious etiology of acute limping in children is a minor traumatic injury [8]. Unfortunately, particularly in younger children, it is common that the pain cannot be accurately localized to one focal area. When there is no concern for infection and pain cannot be localized through history or physical examination, an imaging strategy designed to first localize the source of the pain and subsequently better characterize the cause is typically pursued. Reprint requests to: publications@acr.org
Acutely Limping Child Up To Age 5 PCAs.  Introduction/Background Acute onset of limp or refusal to walk is a common complaint in children, accounting for approximately 4% of visits in one pediatric emergency department [1]. The acutely limping child can be a diagnostic dilemma for clinicians. Most commonly, the acute limp is caused by minor trauma or self-limiting benign conditions but can also be caused by limb-threatening or life-threatening etiologies [2-6]. The cause of limp can usually be determined by a careful history and physical examination. The differential diagnosis of limping is broad and depends on the presence of signs of infection, localization of pain, and history of trauma [6]. The differential diagnosis in a limping child also depends on age. This discussion relates to the initial imaging of the ambulatory child under the age of 5 years who presents with an acute onset of a limp. The presence of fever, elevated white blood cell count, elevated erythrocyte sedimentation rate, or elevated C- reactive protein suggests infection. Localization of pathology is based on site of pain, tenderness, presence of erythema, swelling, and positive physical maneuvers and signs, such as the Trendelenburg test, Galeazzi sign, Patrick/FABER test, pelvic compression test, and psoas sign [7]. A detailed analysis of gait can suggest the diagnosis [6]. Discussion of Procedures by Variant Variant 1: Child up to age 5. Acute limp. Nonlocalized symptoms. No concern for infection. Initial imaging. The most common noninfectious etiology of acute limping in children is a minor traumatic injury [8]. Unfortunately, particularly in younger children, it is common that the pain cannot be accurately localized to one focal area. When there is no concern for infection and pain cannot be localized through history or physical examination, an imaging strategy designed to first localize the source of the pain and subsequently better characterize the cause is typically pursued. Reprint requests to: publications@acr.org