PSEUDOARTHROSIS - US EVALUATION AFTER POSTEROLATERAL SPINAL-FUSION - WORK-IN-PROGRESS

PURPOSE: To determine the value of ultrasound (US) in evaluation of ps eudarthrosis after posterolateral spinal fusion. MATERIALS AND METHODS : In 10 patients who had undergone bilateral posterolateral thoracic o r lumbar fusion with autologous bone graft and instrumentation more th an 9 months previously, US was performed within 1 week before second-l ook surgery. A total of 20 sites each side of midline were evaluated f or the presence of bone graft, solid fusion, clefts, fluid collections , and hardware visibility US findings were compared with those at surg ery. In three patients, standard radiographs were reviewed before US; blinded US evaluation was performed in the remaining seven patients. R ESULTS: At US, all 10 sites of pseudarthrosis seen at surgery were ide ntified correctly. Of 10 sites with solid fusion at surgery, US depict ed six. At four sites (two patients), fusion was mistaken for or obscu red by hardware. Overall, sensitivity was 100%, specificity was 60%, a nd accuracy was 80%. CONCLUSION: US can play a valuable role in the de tection of posterolateral bone graft pseudarthrosis, especially when h ardware is present.