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Study Design. A radiologic assessment of the success of anterior lumbar interbody fusion (ALIF) using thin-section computerized tomography (CT) was performed. Objective. To assess the effect of different types of posterior stabilization on the fusion rate of ALIF. Summary of Background Data. Thin-section CT has shown a higher rate of pseudarthrosis with ALIF than previously reported with standard radiologic methods. Cadaveric studies have shown that posterior stabilization would increase stiffness of the motion segment and is likely to enhance the rate of fusion with ALIF. To our knowledge, the results of thin-section CT of ALIF, with and without posterior stabilization, has not been reported previously. Methods. Patients with discogenic back pain confirmed by diskography underwent ALIF surgery, either as a stand-alone procedure or with posterior stabilization, using translaminar, unilateral pedicle, or bilateral pedicle screws. The 4 cohorts were followed up prospectively, and thin-section CT was used to assess interbody fusion. Results. The fusion rate for stand-alone ALIF was 51%, for patients with supplementary stabilization with translaminar screws 58%, with unilateral pedicle screws 89%, and with bilateral pedicle screws 88%. A significant difference in the fusion rate was found when ALIF was combined with pedicle screw stabilization (P Conclusion. The addition of pedicle screw fixation at ALIF produces a significant increase in the rate of interbody fusion.

Study design A comparative study investigated the use of plain static radiographs, flexion-extension radiographs, and thin-section helical computed tomography (CT) scanning in the assessment of anterior lumbar interbody fusion using carbon fiber cages. Objective To compare plain static radiographs, flexion-extension radiographs, and thin-section helical computed tomography scans in the assessment of lumbar interbody fusion using carbon fiber cages. Summary of background data Lumbar interbody fusion has become a popular procedure for the treatment of discogenic back pain. However, there currently is no universally accepted radiologic assessment tool for determining fusion, and the definitive criteria for diagnosing a successful interbody fusion in the lumbar spine remains controversial. Methods Plain static radiographs, flexion-extension radiographs, and helical computed tomography scans were performed on 32 patients (49 levels) 5 years after anterior lumbar interbody fusion using carbon fiber cages and autologous bone. A radiologist assessed fusion using the Hutter method to detect movement, whereas a spinal surgeon measured movement in degrees using the Simmons method. Helical computed tomography scans were assessed for the presence of bridging trabecular bone. Results The fusion rate was 86% on plain radiographs and 84% with the Hutter method. The fusion rate was 74% with the 2 degrees cutoff, and 96% with the 5 degrees cutoff prescribed by the Food and Drug Administration. Fusion on helical computed tomography scans was observed in 65% of the patients. Conclusions In the radiologic assessment of interbody fusion using carbon fiber cages, the use of plain radiographs and flexion-extension radiographs produced much higher fusion rates than assessment with thin-section helical computed tomography scans. The thin-section helical computed tomography studies clearly demonstrated the radiographic presence or absence of bridging bone, a property that was not seen with plain static radiographs or flexion-extension radiographs.