[Occult fractures of the carpal navicular. Detection by quantitative radioscintigraphy. Social and medico-legal repercussions]. / Les fractures occultes du scaphoïde carpien Détection par la radioscintigraphie quantitative. Incidences sociales et médico-légales.

Fractures of the scaphoid of the wrist are not easily diagnosed and when they are eventually recognized due to late complications, the prognosis is much poorer than it would have been at injury. Medical negligence and poorly-performed or interpreted x-rays are frequently cited as reasons for non-diagnosis. Often these fractures are trabecular, so-called occult, and they cannot be seen on a conventional exam, even if well-performed. Tomography and tomodensitometry have yielded poor results. Quantitative radioscintigraphy (QRS), the exam we are proposing, is a modification of scintigraphy, which is a very sensitive exam (100%) but has little specificity. The first step in QRS is to quantify the fixation of the tracer on the injured side and compare it to that of the uninjured side. If the injured side fixation is double that of the uninjured side, a fracture (often scaphoid) is present. MRI is our reference. In the second step in QRS, a computer-assisted fusion is made of the scintigraphic image and the x-ray (quantitative scintigraphy has the same diagnostic value as MRI). The center of the fracture is localized, thus yielding a specificity of nearly 100% for this exam. Out of a prospective series of 154 patients who had a conventional examination: 41% were diagnosed to have a scaphoid fracture using QSR, therefore a number higher than supposed. Rare carpal fractures were also detected. The cost of this exam is low. The exam climinates non-diagnosed fractures which can lead to non-union and arthrosis. Due to the frequency of carpal trauma, this exam should have a significant effect on the individual, on social security costs and litigations.