Objective: The lateral transpsoas approach for lumbar interbody fusion is a minimal access technique that has been used by some to treat lumbar degenerative conditions, including degenerative scoliosis. Few studies, however, have analyzed its effect on coronal and sagittal plane correction, and no study has compared changes in segmental, regional, and global coronal and sagittal alignment after this technique. The object of this study was to determine changes in sagittal and coronal plane alignment occurring after direct lateral interbody fusion (DLIF).
Methods: The authors performed a review of the radiographic records of 36 patients with lumbar degenerative disease treated with the DLIF technique. Thirty-five patients underwent supplemental posterior fixation to maintain correction. Preoperative and postoperative standing anteroposterior and lateral lumbar radiographs were obtained in all patients for measurement of segmental and regional coronal and sagittal Cobb angles. Standing anteroposterior and lateral 36-in radiographs were also obtained in 23 patients for measurement of global coronal (center sacral vertebral line) and sagittal (C-7 plumb line) balance.
Results: The mean coronal segmental Cobb angle was 4.5° preoperatively, and it was 1.5° postoperatively (p < 0.0001). The mean pre- and postoperative regional lumbar coronal Cobb angles were 7.6° and 3.6°, respectively (p = 0.0001). In 8 patients with degenerative scoliosis, the mean pre- and postoperative regional lumbar coronal Cobb angles were 21.4° and 9.7°, respectively (p = 0.0004). The mean global coronal alignment was 19.1 mm preoperatively, and it was 12.5 mm postoperatively (p < 0.05). In the sagittal plane, the mean segmental Cobb angle measured -5.3° preoperatively and -8.2° postoperatively (p < 0.0001). The mean pre- and postoperative regional lumbar lordoses were 42.1° and 46.2°, respectively (p > 0.05). The mean global sagittal alignment was 41.5 mm preoperatively and 42.4 mm postoperatively (p = 0.7). The average clinical follow-up was 21 months in 21 patients. The mean pre- and postoperative visual analog scale scores were 7.7 and 2.9, respectively (p < 0.0001). The mean pre- and postoperative Oswestry Disability Indices were 43 and 21, respectively (p < 0.0001).
Conclusions: Direct lateral interbody fusion significantly improves segmental, regional, and global coronal plane alignment in patients with degenerative lumbar disease. Although DLIF increases the segmental sagittal Cobb angle at the level of instrumentation, it does not improve regional lumbar lordosis or global sagittal alignment.