Posterior Correction with Segmental Pedicle Screw Fixation Alone in Severe Adolescent Idiopathic Scoliosis Over 70 degrees / 대한정형외과학회잡지

PURPOSE: To evaluate the results of a posterior procedure with segmental pedicle screw fixation in severe adolescent idiopathic scoliosis > or =70 degrees. MATERIALS AND METHODS: Twenty-three adolescent idiopathic patients with a curve magnitude > or =70 degrees subject to segmental pedicle screw fixation were analyzed retrospectively with a minimum follow-up of 2 years (2-7.8 years). There were 19 females and 4 males with a mean age of 14.9 years. All patients, except for 4 patients with King type I, were subjected to thoracic curve fusion. Twenty patients showed a thoracic curve > or =70 degrees (70-96), and 4 patients had a lumbar curve > or =70 degrees (70-77), preoperatively. The preoperative and postoperative standing roentgenograms were used to check the radiological parameters. RESULTS: The mean preoperative thoracic curve was corrected from 79.5+/-9.1 degrees to 25.3+/-5.8 degrees at the most recent follow-up, showing a correction of 67.9+/-7.8% and loss of correction of 2.5+/-1.9%. The mean preoperative lumbar curve was corrected from 72.3+/-3.3 degrees to 30.0+/-10.1 degrees at the most recent follow-up (58.4+/-14.8% curve correction, 2.4+/-2.5% loss of curve correction). The mean preoperative lowest instrumented vertebral tilting was corrected from 30.0+/-7.4 degrees to 10.5+/-5.6 degrees, showing a correction of 64.8+/-20.9%. The preoperative thoracic kyphosis improved from 28.3+/-11.2 degrees (0-50 degrees) to 35.0+/-9.1 degrees (22-53 degrees) postoperatively. There was neither pseudoarthrosis nor complications related to the pedicle screws at the most recent follow-up. CONCLUSION: Segmental pedicle screw fixation without an anterior release procedure in severe adolescent idiopathic scoliosis produced a satisfactory deformity correction with no significant loss of the curve correction. This procedure obviates the need for the anterior release and reduces the complications associated with anterior surgery.

Prevention of the Crankshaft Phenomenon with Posterior Pedicle Screw Fixation in Scoliosis of the Skeletally-Immature Spine / 대한척추외과학회지

STUDY DESIGN: A retrospective study. OBJECTIVES: To evaluate the results of posterior segmental pedicle screw fixation in skeletally immature patients with scoliosis. SUMMARY OF LITERATURE REVIEW: Scoliosis correction, in the immature spine, frequently necessitates additional anterior surgery to prevent the crankshaft phenomenon. With the advent of posterior segmental pedicle screw fixation, it is unclear whether an additional anterior procedure will be required. MATERIAL AND METHODS: Seventeen scoliosis patients (10 idiopathic, 4 congenital and 3 others; 3 males and 14 females) were treated with segmental pedicle screw fixation only. Their results were reviewed for a deformity progression of more than 10 degrees, a rib vertebra angle difference (RVAD) progression of more than 10 degrees, and evidence of adding-on. All the patients had a 0 Risser index at the time of the operation. The mean age and follow-up times were 10.4, ranging from 7.2 to 11.8 years old, and 4.0, ranging from 3.0 to 5.4 years, respectively. RESULTS: The mean preoperative thoracic curve of 55 degrees was corrected to 22 degrees (58% correction) at last follow-up and the nonstructural lumbar curve of 31 degrees was corrected to 10 degrees (67% correction) at last follow-up. Preoperative thoracic kyphosis of 28 degrees was improved to 34 degrees at last follow-up. The RVAD were 23 degrees and 13 degrees, preoperatively and postoperatively, respectively. No patient showed a progression of 10 degrees or more in the postoperative coronal curve or RVAD. One patient had a progression of the deformity caudal to the instrumented segments. There were no neurological or screw-related complications. CONCLUSIONS: Posterior segmental pedicle screw fixation in skeletally immature patients with scoliosis may be effective in preventing the crankshaft phenomenon.

Segmental Pedicle Screw Fixation in Thoracolumbar or Lumbar Idiopathic Scoliosis / 대한정형외과학회잡지

PURPOSE: To analyze surgical outcomes of thoracolumbar and lumbar scoliosis treated with segmental pedicle screw fixation, and to determine the exact distal fusion level. MATERIALS AND METHODS: Seven idiopathic thoracolumbar and lumbar scoliosis patients (6 thoracolumar and 1 lumbar scoliosis, 7 females with mean age of 15.9 years) subjected to segmental pedicle screw fixation with a minimum follow-up of 2 years were retrospectively analyzed for deformity correction, stable vertebra, lower instrumeted vertebral tilt (LIVT) and coronal balance using pre and post-operative standing radiographs. The bending stable vertebra and the rotational correction of L3 were measured in preoperative bending radiographs. The L3 rotation in the bending radiographs was less than Nash-Moe grade II in all patients. The bending stable vertebra was L3 in 4 patients and L4 in 3. An unsatisfactory result was defined as an LIVT of more than 10degrees or a coronal imbalance of more than 10 mm. RESULTS: Distal fusion went down to L3 in 6 patients and L4 in one patient whose bending stable vertebra had been L4 preoperatively. The preoperative average major curve of 52degrees was corrected to 10degrees (81% correction). The preoperative average thoracic curve of 27degrees and the average lumbosacral curve of 26degrees were corrected to 14degrees and 5degrees, respectively. Two patients with distal fusion to L3 showed unsatisfactory results; LIVT was more than 10degrees in both patients and coronal imbalance more than 10 mm in one. Both the patients had bending stable vertebra of L4 preoperatively. CONCLUSION: In the correction of thoracolumbar and lumbar scoliosis with segmental pedicle screw fixation, the curve could be fused to L3 when the L3 rotation in the bending radiograph was less than Nash-Moe grade II and the bending stable vertebra was L3.

Decompensation in Selective Thoracic Fusion by Segmental Pedicle Screw Fixation in King type II Adolescent Idiopathic Scoliosis (AIS): Causative Factors and its Prevention / 대한척추외과학회지

STUDY DESIGN: A retrospective study. OBJECTIVES: To find the causative factors which induce decompensation after selective thoracic fusion with segmental pedicle screw fixation in King type II AIS. SUMMARY OF LITERATURE REVIEW: Pedicle screw fixation enabling enhanced correction is increasing in use in idiopathic scoliosis. However, there are few reports on the decompensation after selective thoracic fusion with pedicle screw fixation in King type II AIS. MATERIALS AND METHODS: Thirty-nine King type II AIS patients subjected to selective thoracic fusion with pedicle screw fixation were analyzed after a minimum follow up of 1 year. They were reviewed using standing roentgenograms. Deviation of center of T1 from center sacral line greater than 2 cm was considered decompensation. RESULTS: Among 39 patients, compensation was in 35 while decompensation in 4 postoperatively. There was no significant differences between the two groups in preoperative thoracic or lumbar curve characteristics such as curve magnitude, apical deviation or apical rotation. There was a significant difference in thoracic curve correction and postoperative T-curve magnitude divided by preoperative L-curve respectively(p= 0.001). CONCLUSION: Decompensation with selective thoracic fusion with segmental pedicle screw fixation in King type II AIS was not induced by preoperative L-curve characteristics nor derotation maneuver. The factor of decompensation was overcorrection, i.e. if thoracic curve correction was more than 75% or if the magnitude of postoperative T-curve was 30% less than that of preoperative L-curve, there was a high risk of decompensation.

Changes in Vertebral Rotation Following Segmental Pedicle Screw Instrumentation and Rod Derotation in Idiopathic Thoracic Scoliosis : Part I - CT Evaluation / 대한정형외과학회잡지

The employment of segmental pedicle screw instrumentation has greatly enhanced the correction of scoliotic deformity. However there is still much controversy on the ability of the system to correct the rotational deformity. This prospective study with 12 idiopathic throacic scoliosis patients subjected to segmental pedicle screw instrumentation was performed to determine the effect of the system on the rotational deformity of idiopathic throacic scoliosis. In addition to the standing films to measure the magnitude of scoliotic curvatures, preand postoperative CT were utilized for the measurement and comparison of angle of rotation relative to the sagittal plane(RAsag.), relative rotation with reference to the upper and lower end vertebrae(RAend), relative rotation with reference to the sacrum(RAsac.), frontal translation(TF) and sagittal translation(TS) for the apical vertebrae. Despite the high correction rate obtained in the frontal plane(average 71.1%) and normalization of sagittal contour, the rotational corrections were statistically insignificant in all parameters and showed no significant correlation to the correction of the curvatures nor horizontal plane displacement as represented by the frontal and sagittal displacement. In conclusions, the segmental pedicle screw instrumentation with rod derotation does not produce significant derotation by itself.