Ewy-Ryong Chung

Thoracic Pedicle Screw Fixation in Spinal Deformities: Are They Really Safe?

Study Design. A retrospective study. Objective. To determine the safety of pedicle screw fixation in thoracic deformity correction. Summary of Background Data. Pedicle screw fixation enables enhanced correction of spinal deformities. However, the technique is still not widely applied for thoracic deformities for fear of neurologic complications. Materials and Methods. A total of 462 patients subjected to thoracic pedicle screw fixation for spinal deformities were analyzed after a minimum follow-up of 2 years. Etiologic diagnoses were idiopathic scoliosis in 330, congenital kyphoscoliosis in 68, kyphosis in 50, and others in 14. They were reviewed using the medical records and preoperative, intraoperative, and postoperative roentgenograms. Computed tomography was performed when screw position was questionable. Results. A total of 4604 thoracic pedicle screws were inserted (10.1 screws/patient). There were 67 screw malpositions (1.5%) in 48 patients (10.4%). The malpositions were inferior in 33, lateral in 18, superior in 12, and medial in 4. Screw-related neurologic complications occurred in four patients (0.8%); these comprised a transient paraparesis and three dural tears. Other complications comprised 11 intraoperative pedicle fractures, 35 screw loosenings, 9 postoperative infections, and 1 pneumothorax. There were no significant screw-related neurologic or visceral complications that adversely affected the long-term result. The deformity correction was 69.9% for idiopathic scoliosis and 60.7% for congenital scoliosis. The sagittal plane deformity correction was 47° for kyphosis. Conclusions. Thoracic pedicle screw fixation is a reliable method of treating spinal deformities, with an excellent deformity correction and a high margin of safety.

Direct Vertebral Rotation: A New Technique of Three-dimensional Deformity Correction With Segmental Pedicle Screw Fixation in Adolescent Idiopathic Scoliosis

Study Design. A prospective study. Objectives. To introduce a new technique, direct vertebral rotation, and to compare the surgical results of direct vertebral rotation with those of simple rod derotation. Summary of Background Data. Pedicle screw fixation with a simple rod derotation maneuver enables a powerful coronal and sagittal plane correction in scoliosis surgery. However, the ability of achieving rotational correction is still unclear. Methods. Thirty-eight adolescent idiopathic scoliosis patients treated with segmental pedicle screw fixation were analyzed. The first group (n = 17) was treated by direct vertebral rotation; the second group (n = 21) was treated by simple rod derotation. All patients had a minimum follow-up of 2 years. Having similar preoperative curve patterns, both groups were evaluated for the deformity correction, lower instrumented vertebral tilt, and spinal balance. Apical vertebral rotation was evaluated by computed tomography scans. Surgical techniques of direct vertebral rotation were as follows: a precontoured rod was inserted into segmental screws on the concave side in thoracic scoliosis; a simple rod derotation was performed; and then the screws on the juxta-apical vertebrae, both on concave and convex sides, were rotated opposite direction to the rod derotation. Then, all the screws were sequentially tightened. Results. In the direct vertebral rotation group, the average preoperative apical vertebral rotation of 16.7° was corrected to 9.6°, showing 42.5% correction, whereas in the simple rod derotation group, the correction was negligible from 16.1° to 15.7° (2.4%). In the direct vertebral rotation group, the average preoperative thoracic curve of 55° was corrected to 12° (79.6%), and the lumbar curve of 39° was corrected to 7° (80.5%). In the simple rod derotation group, the preoperative thoracic curve of 53° was corrected to 17° (68.9%), and the lumbar curve of 39° was corrected to 16° (62.2%). The average lower instrumented vertebral tilt correction was 80.6% and 66.3% in the directvertebral rotation and the simple rod derotation group, respectively. There were statistically significant differences in the coronal curve, lower instrumented vertebral tilt, and rotational correction (P < 0.05, Mann-Whitney U test). Thoracic kyphosis was improved in both groups. Conclusions. Segmental pedicle screw fixation with “direct vertebral rotation” showed better rotational and coronal correction than “simple rod derotation.”

Posterior vertebral column resection for severe rigid scoliosis

Study Design. Retrospective study. Objective. To report on the technique and results of posterior vertebral column resection (PVCR) for severe rigid scoliosis. Summary of Background Data. The treatment of severe rigid scoliosis is a demanding surgical challenge. Conventional procedures such as combined anteroposterior instrumentation enable limited correction. In rigid scoliosis, vertebral column resection is a better option for accomplishing translation of spinal column. PVCR is performed through a single posterior approach. Methods. A total of 16 patients with scoliosis (average age 29 years) subjected to PVCR were retrospectively reviewed after a minimum follow-up of 2 years (range 2−6.8). The indication for PVCR was scoliosis more than 80°, with flexibility less than 25%. The radiographic parameters were evaluated, and clinical records were reviewed. Results. The number of vertebrae removed averaged 1.3, and 21 total (15 thoracic and 6 lumbar). Average fusion extent was 10.6 vertebrae. The mean preoperative scoliosis of 109.0° was corrected to 45.6° (59% correction) at the most recent follow-up, and the minor curve of 59.3° was corrected to 29.2° (51% correction). The mean preoperative coronal imbalance of 4.0 cm was improved to 1.0 cm at the most recent follow-up, and sagittal imbalance of 4.2 cm was improved to 1.6 cm. Complications were encountered in 4 patients, including 1 complete paralysis, 1 hematoma, 1 hemopneumothorax, and 1 proximal junctional kyphosis. Conclusions. PVCR is an effective alternative for severe rigid scoliosis. It is a highly technical procedure and should only be performed by an experienced surgical team.

Selective thoracic fusion with segmental pedicle screw fixation in the treatment of thoracic idiopathic scoliosis: more than 5-year follow-up.

Study Design. Retrospective study. Objectives. To evaluate outcomes of selective thoracic fusion with segmental pedicle screw fixation in thoracic idiopathic scoliosis with a minimum 5-year follow-up. Summary of Background Data. Segmental pedicle screw fixation has been proven to enable true segmental control and greater correction both in coronal and sagittal planes of scoliosis. However, there is no long-term study of selective thoracic fusion with segmental pedicle screw fixation in thoracic idiopathic scoliosis. Methods. Two hundred and three thoracic idiopathic scoliosis patients with 236 thoracic curves subject to selective thoracic fusion with segmental pedicle screw fixation were analyzed. Mean patient age at the time of operation was 13.8 years (range: 8.9–18). Results. The preoperative thoracic curve of 51 ± 12° was corrected to 16 ± 7° (69% correction, 3% loss of correction) at the most recent follow-up. The noninstrumented lumbar curve of 30 ± 10° was corrected to 10 ± 8° (66% correction, 5% loss of correction) at the most recent follow-up. The preoperative thoracic kyphosis of 18 ± 11° and the lumbar lordosis of 43 ± 10° were improved to 23 ± 8° and 46 ± 9°, respectively, at the most recent follow-up. There was no junctional kyphosis at the most recent follow-up. Coronal decompensation at the most recent follow-up occurred in 10 patients. Postoperative adding-on occurred in 17 patients, who were fused two levels short of the neutral vertebra. Of the 2,867 thoracic pedicle screws inserted in the thoracic level, 43 screws were found to be malpositioned (1.5%), but they did not cause neurologic complications or adversely affect the long-term results. Conclusions. Selective thoracic fusion with segmental pedicle screw fixation in thoracic idiopathic scoliosis had satisfactory radiographic and clinical outcomes after surgery and has been well-maintained for minimum 5-year follow-up. It is a safe and effective method for preservation of lumbar motion segments as well as for restoration and maintenance of both coronal and sagittal alignment.

Posterior vertebral column resection in fixed lumbosacral deformity.

Study Design. Retrospective study. Objectives. To report the results and the technique of posterior vertebral column resection (PVCR) in fixed lumbosacral deformity. Summary of Background Data. Fixed lumbosacral deformity has gross imbalance as well as progressive compensatory thoracolumbar deformity because of the absence of a mobile spine caudally. There is no consensus of the surgical treatment of fixed lumbosacral deformity. Fixed lumbosacral deformity can be managed by PVCR, which not only corrects the deformity but also restores the trunk balance by translation of spinal column. Methods. Twenty-five consecutive fixed lumbosacral deformity patients subjected to PVCR were reviewed after a minimum follow-up of 2 years. The apical vertebra and the ultimately resected vertebra were below L4 in most cases. Etiologic diagnoses were congenital scoliosis in 6, congenital kyphoscoliosis in 3, post-traumatic kyphosis in 2, and postinfectious kyphosis in 14. The average age at the operation was 38 years (range, 2.5–61 years) with a male:female ratio of 7:18. The indication for PVCR was fixed lumbosacral deformities that could not be brought to a reasonable balance on traction or forced side bending. Before surgery, 12 patients (48%) presented with neurologic compromise and 20 patients (80%) presented with intractable back pain. The surgical technique consisted of segmental pedicle screw fixation, decompression of neural structures, and resection of the vertebral column at the apex of the deformity via the posterior route, followed by deformity correction and global fusion. During the resection, all the nerve roots were preserved. Results. Two and one tenth (2.1) vertebrae removed on average (range, 1–5 vertebrae), and 52 in all. The average fusion extent was 4.5 vertebrae (range, 2–8 vertebrae). The anterior column reconstruction was carried out with autogenous bone graft in all patients and additional insertion of titanium mesh in 12. The distal anchor went down to L5 in 4 patients, S1 in 12, and S2 in 9. Preoperative scoliosis of 38° ± 12° was corrected to 15° ± 8° (60% correction) at most recent follow-up, and preoperative kyphosis of 35° ± 25° was corrected to −5° ± 11° (40° correction). The compensatory coronal curve of 26° was spontaneously corrected to 12° at most recent follow-up. The preoperative thoracic lordosis of −16° was corrected to 4° at most recent follow-up, and the preoperative lumbar kyphosis of 20° was corrected to −17°. Preoperative coronal imbalance of 2.0 cm was improved to 0.9 cm at most recent follow-up, and preoperative sagittal imbalance of 9.3 cm was improved to 4.6 cm. Mean operation time was 280 minutes with a blood loss of 2,810 mL. The preoperative neurologic compromise was improved in all patients, and pain was reduced to less than half of preoperative visual analog analog scale in 17 patients. The following complications were encountered in 5 patients: 2 with transient neurology that spontaneously improved without a sequel within 6 months, 2 with compression fractures at proximal adjacent vertebra, and 1 with pseudarthrosis. Conclusions. PVCR is an effective procedure for the management of fixed lumbosacral deformity. It provides satisfactory correction and improved functional outcomes. However, it is a technically demanding and exhausting procedure with possible risks for complications.

Anterior-posterior surgery versus posterior closing wedge osteotomy in posttraumatic kyphosis with neurologic compromised osteoporotic fracture.

Study Design. Retrospective study. Objectives. To compare the surgical results between combined anterior–posterior procedures and posterior closing wedge osteotomy procedures in patients with posttraumatic kyphosis and neurologic compromise secondary to osteoporotic fractures. Summary of Background Data. Combined anterior–posterior procedures are usually recommended in cases of kyphotic deformities with neurologic deficit secondary to osteoporosis. However, combined anterior–posterior surgery is associated with significant morbidity in elderly patients. Materials and Methods. Twenty-six patients with posttraumatic kyphosis and neurologic compromise secondary to osteoporotic fracture were indicated for operative intervention using either a combined anterior–posterior surgery (n = 11) or a posterior closing wedge osteotomy procedure (n = 15). The results of the two procedures were analyzed. The average patient age at the operation was 62.6 years (range: 50–82) with a 12:14 male-to-female ratio. Mean follow-up was 3.5 years (range: 2.1–5.4). Preoperative interval from injury to operation was 15.4 months (range: 1–36). There were 20 thoracolumbar (T12-L1) fractures and six lumbar fractures indicated for operative intervention. Results. In the combined anterior–posterior group, the mean operative time was 351 minutes with a mean blood loss of 2,892 mL. In the posterior closing wedge osteotomy group, the mean operative time was 215 minutes with blood loss of 1,930 mL. Eighteen patients showed a postoperative improvement in Frankel grading, 64% (7/11) in the combined anterior–posterior group, and 73% (11/15) in posterior closing wedge osteotomy group. There were no neurologic or vascular complications in either group. In the combined anterior–posterior group, there were five complications: two postoperative pneumonias, one superficial infection, and two distal screw loosening. There were only two complications in the posterior closing wedge osteotomy group: two distal screw loosening. One of the four cases of distal screw loosening required surgical revision. The other three cases were treated by bracing for more than 6 months. Conclusions. Although technically demanding, the posterior closing wedge osteotomy procedure demonstrated a better surgical result with significant less mean operative time and mean blood loss (P < 0.05). It may be a better alternative than a combined anterior–posterior procedure in patients with posttraumatic kyphosis and neurologic compromise secondary to osteoporotic fracture.

Determination of Distal Fusion Level With Segmental Pedicle Screw Fixation in Single Thoracic Idiopathic Scoliosis

Study Design. A retrospective study was conducted. Objective. To determine the exact distal fusion level in the treatment of single thoracic idiopathic scoliosis (King Types 3 and 4) with segmental pedicle screw fixation. Summary of Background Data. Pedicle screw fixation effectively shortens the distal fusion extent by improved three-dimensional deformity correction. However, the selection of distal fusion extent remains controversial in single thoracic idiopathic scoliosis. Methods. This study analyzed 42 patients with single thoracic adolescent idiopathic scoliosis (32 King 3 patients and 10 King 4 patients) who underwent segmental pedicle screw fixation and had a minimum follow-up period of 2 years (range, 2–6 years). The patients were grouped according to the distal fusion level with reference to the standing neutral rotated vertebra (NV) for comparison of deformity correction and spinal balance using standing radiographs. Failure to restore an adequate trunk balance and progression or extension of the primary curve (adding on) was considered unsatisfactory. Results. Preoperative 50° ± 11° of thoracic deformity was corrected to 13° ± 5°, for a curve correction of 74%. Preoperative 23° ± 7° of lumbar deformity was corrected to 2° ± 8°, for a curve correction of 93%. Curve correction was not significantly affected by King type or distal fusion level (P > 0.05). Postoperative unsatisfactory results were obtained in 14 patients. When the preoperative NV was the same or one level distal to end vertebra (EV), fusion down to NV was satisfactory (14/14). When the preoperative NV was more than two levels distal to EV, fusion down to one level shorter than NV (NV−1) also was satisfactory (9/9). However, when fusion down to NV−2 or shorter was performed, the chances of adding on were higher (14/19;P < 0.01). Preoperative 17° ± 8° of thoracic kyphosis was improved to 24° ± 7°. Conclusions. In single thoracic idiopathic scoliosis, NV is an important factor for the determination of fusion level. When preoperative NV and EV show no more than two-level gap differences, the curve should be fused down to NV. When the gap is more than two levels, fusion down to NV−1 is satisfactory, saving one or two motion segments, as compared with fusion extending to the stable vertebra.

Indications of proximal thoracic curve fusion in thoracic adolescent idiopathic scoliosis: Recognition and treatment of double thoracic curve pattern in adolescent idiopathic scoliosis treated with segmental instrumentation

Study Design. A retrospective study. Objectives. To determine the indications of fusing the proximal thoracic curve when treating idiopathic thoracic scoliosis with segmental instrumentation. Summary of Background Data. Failure to recognize a significant proximal thoracic curve often results in postoperative shoulder asymmetry due to relative overcorrection of the lower thoracic curve. With segmental instrumentation that enhances the correction of the instrumented curve, the double thoracic curve pattern that needs fusion of both the proximal and the distal thoracic curves should be redefined. Methods. Forty patients with thoracic adolescent idiopathic scoliosis with a right lower thoracic curve of more than 40° and a left proximal thoracic curve of more than 25° treated by segmental pedicle screw instrumentation were analyzed after a minimum follow-up of 2 years. Results. Of the 40 patients, 18 were treated by fusion of both the proximal and the distal curves, whereas 22 were treated by fusion of the distal curve only. The postoperative shoulder height difference (SHD, in millimeters) was 0.9 × preoperative SHD + 5.3 for the fusion of both curves and 0.6 × preoperative SHD + 12 for the distal curve fusion (linear regression), showing that proximal thoracic curve fusion improved the SHD when the left shoulder was level with or higher than the right. Conclusions. Idiopathic thoracic scoliosis with a proximal thoracic curve of more than 25° and level or elevated left shoulder should be considered a double thoracic curve pattern and should be treated by fusing both the proximal and the distal curves when using segmental instrumentation.