The excretion of hydroxyproline in urine during the healing of fractures and after sagittal splitting of the mandible.

Total excretion of hydroxyproline was measured in patients with fractures of long bones and in patients undergoing sagittal splitting of the mandible. In both patient groups excretion of hydroxyproline was twice that of normal healthy subjects. The amount of excreted hydroxyproline in patients with fractures was related to the site of the fracture, to the age of the patient, and the form of therapy. The excretion of hydroxyproline was found to be variable after wire adaptation of mandiblular osteotomy segments and after sagittal splitting without wire adaptation. Quantitative analysis of the excretion of hydroxyproline in urine does not therefore permit conclusions about the bone healing process.