534 THE JOURNAL OF BONE AND JOINT SURGERY OVERGROWTH OF THE FEMUR AFTER FRACTURE IN CHILDHOOD AN INCREASED EFFECT IN BOYS

Forty-four children, treated conservatively for fracture of the shaft of a femur, were studied radiographically to assess the consequent increase in longitudinal growth of the bone. Overgrowth averaged 8.1 mm and was shown to be significantly greater in boys than in girls. Overgrowth did not appear to be influenced by the age of the patient, the type of injury, the type or site of the fracture, the amount ofoverlap of the fragments or by the handedness of the patient. It is well recognised that there is acceleration of the growth rate of the immature femur after a fracture (Truesdell 1921: Edvardsen and Syversen 1976). Most reports have been based on clinical measurement, which means that errors of 5 mm are possible in the measure-ment of limb length (Barfod and Christensen 1958-9; Kohan and Cumming 1982). Radiographic measure-ment is accurate to within 1 mm but has been used in few papers ( Meals 1979: Reynolds 198 1), some of which have reported either small or incompletely analysed series (David 1924; Greville and Ivins 1957). All studies have assumed that the femora were of equal length before fractire. \Ve have made a radiographic study of 50 children after closed fracture of one femur with a view to analysing the results according to a number of factors, including the sex of the child and the type, site and overlap of the fracture. PATIENTS AND METHODS A consecutive series of 50 children aged from seven months to 12 years 3 months were treated conservatively for a single closed fracture of the femur under the direction of one orthopaedic surgeon. There were 44 children with a complete fracture of the shaft of th