We made a prospective study of the incidence and natural history of al
godystrophy and associated changes in bone mineral density in the ankl
es and feet of 60 consecutive patients who had suffered unilateral fra
ctures of the tibial shaft. At bone union, 18 patients showed signs of
algodystrophy. Its development was independent of the type of fractur
e management and of the severity of injury. Patients with algodystroph
y lost significantly more bone mineral than did those without but the
degree of this loss was independent of the type of treatment and of th
e time to fracture union. In most cases the symptoms resolved within s
ix months of fracture union but in four patients they were still prese
nt at one year and two of these had not returned to work.