Pseudarthrosis: US evaluation after posterolateral spinal fusion: work in progress.

Abstract

To determine the value of ultrasound (US) in evaluation of pseudarthrosis after posterolateral spinal fusion. In 10 patients who had undergone bilateral posterolateral thoracic or lumbar fusion with autologous bone graft and instrumentation more than 9 months previously, US was performed within 1 week before second-look surgery. A total of 20 sites each side of midline were evaluated for the presence of bone graft, solid fusion, clefts, fluid collections, and hardware visibility. US findings were compared with those at surgery. In three patients, standard radiographs were reviewed before US; blinded US evaluation was performed in the remaining seven patients. At US, all 10 sites of pseudarthrosis seen at surgery were identified correctly. Of 10 sites with solid fusion at surgery, US depicted six. At four sites (two patients), fusion was mistaken for or obscured by hardware. Overall, sensitivity was 100%, specificity was 60%, and accuracy was 80%. US can play a valuable role in the detection of posterolateral bone graft pseudarthrosis, especially when hardware is present.