RADIOGRAPHIC AND HISTOLOGIC OBSERVATIONS IN CENTRAL FRACTURES OF THE TALUS

In a prospective study of central fractures of the talus, radiological data (plain radiography, CT, MRI) were scrutinized in terms of correl ation with histological findings (biopsy taken at time of screw remova l). The study looked at nine fractures in eight patients aged 14-48 ye ars. There was one fracture of Hawkins type I, one fracture of type II , four fractures of type III ,and three corpus fractures. All were ope rated on within 24 h after injury; seven had screw fixation, two had a daptation with K wires. The patients were kept non-weight-bearing for 14-53 weeks. Duration of follow-up was 2 years or more in all but one patient. In the final radiograph the talus was intact in four patients , while four showed a partial avascular collapse; in one patient,a par tial collapse was doubtful. Histology taken 16 - 52 weeks after injury showed osteocyte-free original bone in all cases, with deposition of new bone varying in extent. Hawkins sign was partially positive in six patients, positive in one,and negative in one. Decalcification as wel l as fracture healing can be better followed by CT than by plain radio graphy. MRI appeared normal in five patients, partially pathological i n two, and abnormal in one. A positive Hawkins sign and normal signal behavior can be seen as prognostically favorable signs. However, in th e case of a central talus fracture, even with a favorable course osteo necrosis of at least a pa rt of the talus with gradual replacement by new bone occurred. Vascularization of the central talus seems to be di sturbed more frequently than is reflected radiologically.