ULTRASOUND FOR THE EARLY DIAGNOSIS OF TIBIAL FRACTURE-HEALING AFTER STATIC INTERLOCKED NAILING WITHOUT REAMING - HISTOLOGIC CORRELATION USING A CANINE MODEL

Objective: Ultrasound is thought to be clinically useful in evaluating bone formation through its presumed identification of fracture callus . However, documentation of the actual histology of the tissue identif ied by ultrasound has been lacking. The purpose of this study was to d etermine the histologic composition of the hyperechoic tissue ''seen'' by ultrasound. Study Design: Unilateral fractures were created in eig ht canine tibias and then fixed by using locked intramedullary nailing without reaming. The limbs were studied at two, three, four, six, and eight weeks postoperatively with plain radiographs, ultrasound, and u ltrasound-directed needle biopsy, Results: The presence of a hyperecho ic ultrasound signal was found to have a 100 percent correlation with the presence of hard fracture callus biopsy tissue. in addition, fract ure union by ultrasound criteria significantly predated radiographic f racture union (5.6 vs. 7.3 weeks, p = 0.05). Conclusions: These result s support and provide a scientific basis for the clinical use of ultra sound to assess tibial fracture healing following static interlocked n ailing without reaming.