Use of ultrasonography in evaluation of new bone formation in patients treated by the method of Ilizarov.

BACKGROUND Lengthening of bones by gradually distracting bone fragments using an external apparatus by Ilizarov, is a long process with numerous complications. The greatest threats in limb lengthening are poor new bone formation as well as premature consolidation of the newly generated bone. The purpose of this study was to determine the importance of ultrasonography in evaluation of bone formation in limb lengthening. PATIENTS AND METHODS The study involved 31 patients, in whom 52 long bones were lengthened by the Ilizarov method at the University Clinic for Orthopaedic Surgery in Skopje from 2006 to 2010. The study revealed the results of ultrasonographic analysis of new bone formation at four various stages of limb lengthening. The analysis of the results of ultrasonographic examination of bones throughout the lengthening process was based on the form and dimensions of the obtained ultrasonographic parameters--indicators of new bone formation--as well as on the appearance of the cortical margin at the distraction site. RESULTS Tiny, solitary and confluent hypo-echogenic foci developed on sonograms approximately 2 weeks after distraction was commenced. At stage I a new cortical margin was detected in 30.77%. The number of initial small indicators significantly decreased throughout lengthening. At stage IV the solitary indicators rate was 9.51%, whereas the linear indicators rate significantly increased from 22.12% at the first stage to 54.3% at the last stage. the cortical margin was presented in all 52 bones at III and IV stage of lengthening. DISCUSSION AND CONCLUSIONS Ultrasonography enabled an evaluation of the degree of new bone formation and it preceded the radiographic changes at the distraction site. This helped to determine the surgical lengthening and to avoid numerous complications.