Segmental pedicle screw instrumentation in idiopathic thoracolumbar and lumbar scoliosis

The role of posterior correction and fusion in thoracolumbar and lumbar sco liosis as well as pedicle screw instrumentation in scoliosis surgery are ma tters of debate. Our hypothesis was that in lumbar and thoracolumbar scolio sis, segmental pedicle screw instrumentation is safe and enables a good fro ntal and sagittal plane correction with a fusion length comparable to anter ior instrumentation. In a prospective clinical trial, 12 consecutive patien ts with idiopathic thoracolumbar or lumbar scolioses of between 40 degrees and 60 degrees Cobb angle underwent segmental pedicle screw instrumentation . Minimum Follow-up was 4 years (range 48-60 months). Fusion length was def ined according to the rules for Zielke instrumentation, normally ranging be tween the end vertebrae of the major curve. Radiometric analysis included c oronal and sagittal plane correction. Additionally, the accuracy of pedicle screw placement was measured by use of postoperative computed tomographic scans. Major curve correction averaged 64.6%, with a loss of correction of 3 degrees. The tilt angle was corrected by 67.0%, the compensatory thoracic curve corrected spontaneously according to the flexibility on the preopera tive bending films, and led to a satisfactory frontal balance in all cases. Average fusion length was the same as that of the major curve. Pathologica l thoracolumbar kyphosis was completely corrected in all but one case. One patient required surgical revision with extension of the fusion to the midt horacic spine due to a painful junctional kyphosis. Eighty-five of 104 scre ws were graded "within the pedicle", 10 screws had penetrated laterally, 5 screws bilaterally and 4 screws medially. No neurological complications wer e noted. In conclusion, despite the limited number of patients, this study shows that segmental pedicle screw instrumentation is a safe and effective procedure in the surgical correction of both frontal and sagittal plane def ormity in thoracolumbar and lumbar scoliosis of less than 60 degrees, with a short fusion length, comparable to anterior fusion techniques, and minima l loss of correction.