Harris lines, also known as growth arrest lines, are lines of increased bone density that represent the position of the growth plate at the time of insult to the organism and formed on long bones due to growth arrest. They are only visible by radiograph or in cross-section. The age at which the lines were formed can be estimated from the radiographs. Harris lines are often discussed as a result of juvenile malnutrition, disease or trauma. Other studies suggest a reconsideration of Harris lines as more of a result of normal growth and growth spurts, rather than a pure outcome of nutritional or pathologic stress.