Correlation of radiologic assessment of lumbar spine fusions with surgical exploration.

Although inspection of posterolateral lumbar fusion is the best method of determining its solidity, routine exploration of the fusion is somewhat impractical because of the morbidity and expense involved. Removal of internal fixation devices or implantable batteries or reoperation for failed back surgery enabled the exploration and assessment of lumbar spine fusions in 214 operations on 175 patients. The preoperative radiologic assessment (plain roentgenographs, polytomography, bending films, and computed tomographic scans) were correlated with surgical findings. This study indicated a significant percentage of inaccuracy of all radiologic modalities used. Noncorrelations were present in 36% of plain roentgenographs, 41% of polytomograms, 38% of bending films, and 43% of computed tomographic scans. Radiologic inaccuracy was manifest on both the positive and negative sides. Computed tomographic scanning presented the lowest percentage of inaccuracy (22%) and bending films the highest percentage (27%). Based on these findings, there exists the need for more accurate noninvasive methods to determine the solidity of spine fusions.