[Protective limp].

Limping in a child is a frequent reason for consultation, sometimes as an emergency. A distinction should be made between a protective limp, to avoid painful weight bearing, and an equilibration limp, which corresponds to an adaptation to a disturbance of muscular activity with a neuromuscular or osteoarticular origin. Etiological analysis of a protective limp is essentially based on the history and examination. Further radiological or biochemical investigations contribute to the diagnostic process and are essential in limps of recent onset. Broadly speaking, in children aged between one and two years, the main etiological hypothesis, in terms of frequency and potential seriousness, is osteoarticular infection, although fractures are also common. In children aged between three and eight years, osteoarticular infection should be sought as a priority. The diagnosis of acute transient synovitis (irritable hip) should only be made after excluding other conditions including benign bone tumours (such as ostioid osteoma), malignant tumours, inflammatory monoarthritis, primary osteochondritis of the hip, trauma with or without fracture, apophysitis, leukemia, etc. The diagnosis of acute transient synovitis should be questioned if the condition persists for more than seven days. After the age of nine years, the diagnosis that is important not to miss is proximal femoral epiphysiolysis, because this condition can have serious implications for the future function of the hip. The other diagnoses already cited remain possibilities. Finally, a psychogenic aetiology, tendinitis, or sprain should not be considered in children, and they risk delaying the diagnosis of a potentially serious condition. The aetiology of an equilibration limp is based on a precise clinical examination, aimed at detecting orthopedic or neurological pathology, which will direct further investigations.