Study Design. A retrospective matched cohort study. Objective. To comprehensively compare the 2-year postoperative results of posterior correction and fusion with segmental pedicie screw instrumentation versus those with hook constructs in adolescent idiopathic scoliosis (AIS) treated at a singie institution. Summary of Background Data, Despite the reports of satiefactory correction and maintenance of Scoliotic curves by pedicle screw instrumentation compared to hook constructs, few reports on the comprehensive comparison of segmental pedicle screw instrumentation versus hook instrumentation exist Materials and Methods. A total of 52 patients with AIS at a single institution who underwent a posterior spinal fusion with segmental pedicie screw (26) or hook (26) instrumentation were sorted and matched accoridng to four criteria similar age at surgery (14.8 years in pedicie screw group and 14.2 years in hook group), identical Lenke curve types, same number of fused vertebres (11.7 in each group), and identical operative methods (18 posterior spinal fusions with thoracoplasty, 4 posterior spinal fusions with iliac crest bone graft, and 4 anterior and posterior spinal fusions in each group). Petients were eveluated before surgery, immediate after surgery, and at the 2-year follow-up according to radiographic changes in curve correction, pulmonary function tests, operative time, intraoperative blood loss, implant costs, and SRS-24 scores. Results. After surgery, the average major curve correction was 76% in the scraw group and 60% in the hook group (P < 0.001). At the 2-year follow-up, loss of the mejar curve correction was less in the screw group (6.4%) compared with the hook group (8.0%) (P = 0.35), Postoparative globel coronal and sagittal balance was similar in both groups. An everage of 0.8 leveis from the distal end vertebre was saved using pedicie screws compared with hook constructs (P = 0.002). Postoperative 2-year proximal junctional change in the sagittal plane (angie between uppermost instrumented vertebra and two verte bral bodies above the uppermost-instrumented vertebra) was 9° in the screw group and 6° in the hook group (P = 0.19). Postoparative 2-year distal junctional change in the sagittal plane was similar in both groups. Operative time averaged 341 minutes in the screw group and 338 minutes in the hook group (P = 0.86), and intraoperative blood loss was similar in both groups (879 mL in screw group vs. 896 mL in hook group) (P = 0.12). Average implant cost in the hook group (11.8 fixation points, 5,818 U.S. dollars) was significantly lower than that of the screw group (17.1 fixation points; 11,508 U.S. dollars) (P < 0.001). Two years following surgery, the screw group demonstrated improved percent predicted pulmonary function values compared with that of the hook group (FVC. 80%→ 79% in screw group vs. 92%→ 74% in trock group, P = 0.0068; FEV-1, 73%→ 76% in screw group vs. 80%→ 79% in hook group, P = 0.017). Postoperative 2-year SRS-24 scores ware similar in both groups iscrew group [97] vs. hook group (101)(P = 0.15). There were no neurologic or visceral complications related to hook or pedicle screw instrumentation. Conclusion. Pedicle screw instrumentation, although more expensive, offers a significantly battey major and minor curve correction without neurologic problems and improved pulmonary function values in the operative treatment of AIS and enabias a slightly sharter fusion length then segmental hook intrumentation.

Comparative Analysis of Pedicle Screw Versus Hook Instrumentation in Posterior Spinal Fusion of Adolescent Idiopathic Scoliosis

Background:To our knowledge, a prospective, randomized study comparing operative and nonoperative treatment of a thoracolumbar burst fracture in patients without a neurological deficit has never been performed. Our hypothesis was that operative treatment would lead to superior long-term clinical out

Operative compared with nonoperative treatment of a thoracolumbar burst fracture without neurological deficit. A prospective, randomized study.

Two hundred and nineteen patients with untreated adolescent idiopathic scoliosis who were seen at the University of Iowa between 1932 and 1948 were studied, and recent information was available on 194 of the patients. The mortality rate was 15 per cent. Backache was somewhat more common in these pa- tients than in the general population, although it was never disabling. The backache was unrelated to the presence of osteoarthritic changes on roentgenograms. Many curves continued to progress slightly in adult life, particularly thoracic curves that had reached be- tween 50 and 80 degrees at skeletal maturity. The lum- bar components of combined curves between 50 and 74 degrees also tended to progress. Pulmonary function was affected only in patients with thoracic curves.

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Long-term follow-up and prognosis in untreated patients*

STUDY DESIGN A prospective randomized clinical study. OBJECTIVES To evaluate supplementary pedicle screw fixation (Cotrel-Dubousset) in posterolateral lumbar spinal fusion. SUMMARY OF BACKGROUND DATA The rationale behind lumbar fusion is to eliminate pathologic motion to relieve pain. To improve fusion rates and to allow reduction, a rigid transpedicular screw fixation may be beneficial, but the positive effect of this may be counter-balanced by an increase in complications. METHODS The inclusion criteria were severe, chronic low back pain from spondylolisthesis Grades 1 and 2 or from primary or secondary degenerative segmental instability. One hundred thirty patients were randomly allocated to receive no instrumentation (n = 66) or Cotrel-Dubousset instrumentation (n = 64) in posterolateral lumbar fusion. Variables were registered at the time of surgery and at 1 and 2 years after surgery. RESULTS Follow-up was achieved in 97.7% of the patients. Fusion rates deduced from plain radiographs were not significantly different between instrumented and noninstrumented groups. The functional outcome assessed by the Dallas Pain Questionnaire improved significantly in both groups, and there were no significant differences in results between the two groups, except for significantly better (P < 0.06) functional outcome in relation to daily activities in the instrumented group when neural decompression had been performed. The global patients' satisfaction was 82% in the instrumented group versus 74% in the noninstrumented group (not significant). Fixation of instrumentation increased operation time, blood loss, and early reoperation rate significantly. Patients experienced only a few minor postoperative complications; none were major. Two infections appeared in the Cotrel-Dubousset group. Significant symptoms from misplacement of pedicle screws were seen in 4.8% of the instrumented patients. CONCLUSIONS Lumbar posterolateral fusion with pedicle screw fixation increases the operation time, blood loss, and reoperation rate, and leads to a significant risk of nerve injury. The functional outcome improves significantly with high patient satisfaction, with or without instrumentation. No significant differences were observed between the two groups in functional outcome and fusion rate. The only gain in functional outcome from instrumentation was found in the daily activity category in patients with supplementary neural decompression. The results of this study do not justify the general use of pedicle screw fixation alone as an adjunct to posterolateral lumbar fusion.

1997 Volvo Award winner in clinical studies. The effect of pedicle screw instrumentation on functional outcome and fusion rates in posterolateral lumbar spinal fusion: a prospective, randomized clinical study.

Study design Systematic review. Objective To review the published literature on the use of pedicle screws in pediatric spinal deformity to quantify the risks and complications associated with pedicle screw instrumentation, particularly in the thoracic spine. Summary of background data The use of pedicle screws in adolescent scoliosis surgery is common. Although many reports have been published regarding the use of pedicle screws in pediatric patients, there has been no systematic review on the risks of complications. Methods PubMed, Ovid Medline, and Cochrane databases were searched for studies reporting the use of thoracic pedicle screws in pediatric deformity. We excluded articles dealing with neuromuscular scoliosis or bone dysplasia to focus mostly on adolescent thoracic idiopathic scoliosis and the likes. We then searched for cases reports dealing with thoracic pedicle screws complications. Results This systematic review retrieved 21 studies with a total of 4570 pedicle screws in 1666 patients. The mean age of the patients was 17.6 years; 812 patients were women and 252 were men, and 5 studies did not identify sex. Overall, 518 (4.2%) screws were reported as malpositioned. However, in studies in which postoperative computed tomography scans were done systematically, the rate of screw malpositioning was as high as 15.7%. The reported percentage of patients with screw malpositioned is around 11%. Eleven patients underwent revision surgery for instrumentation malposition. Other complications reported include loss of curve correction, intraoperative pedicle fracture or loosening, dural laceration, deep infection, pseudarthrosis, and transient neurologic injury. There were no major vascular complications reported in these 21 studies. We could identify 9 case report articles dealing with complications of pedicle screws. Such complications were mostly either vascular (10 cases) or neurologic (4 cases), without any irreversible complications. Conclusion Malposition is the most commonly reported complication of thoracic pedicle screw placement, at a rate of 15.7% per screw inserted with postoperative computed tomography scans. The use of pedicle screws in the thoracic spine for the treatment of pediatric deformity has been reported to be safe despite the high rate of patients with malpositioned screws (11%). Major complications, such as neurologic or vascular injury, were almost never reported in this literature review of case series. Cases reports on the other hand have started to identify such complications.

Complications of pedicle screw fixation in scoliosis surgery: a systematic review.

The relationship between herniated lumbar disc and abnormalities of the transverse process of the lumbosacral junction was investigated. Two hundred consecutive patients with positive myelographic findings of herniated lumbar disc were reviewed. Sixty patients presented abnormalities of the transverse process to satisfy the criteria for lumbosacral transitional vertebra. A new classification of lumbosacral transitional vertebra is presented based upon the morphologic and clinical characteristics with respect to herniated nucleus pulposus. Type I represents a "forme fruste" of lumbosacral transitional vertebra and shows no difference in the incidence of the location of herniations. In types III and IV, there are no herniations at the level of the lumbosacral transitional vertebra and no increase in the incidence of herniations just proximal to the lumbosacral transitional vertebra. The Type II lumbosacral transitional vertebra presents herniated lumbar disc at the level of transition. It also presents a greater than normal incidence of herniations at the level just above the lumbosacral transitional vertebra.

Lumbosacral transitional vertebrae and their relationship with lumbar extradural defects.

The outcomes of traumatic two- and three-column lumbar burst fracture patients treated operatively and nonoperatively were investigated with respect to treatment complications, resumption of employment, and quality of life. Data were obtained from hospital records, radiographs, and written questionnaires. Of 93 patients diagnosed with lumbar fracture between January 1987 and December 1989, 22 met the criteria for study (12 operative, ten nonoperative). Exclusion was based on single-column compression or chance fractures, neurologic compromise, and nontraumatic fractures. The patient groups had distinctly different fracture patterns based on degree of anterior column compression (ACC). Trends toward significant differences in kyphotic angulation and canal compromise were noted. There were no preoperative complications. Varying modes of external immobilization were used in both groups. One patient in each group used narcotic medications for pain at final follow-up evaluation. When comparing the operatively and nonoperatively treated lumbar burst fracture patients in this study group, no significant difference in treatment outcome was established. Nonoperative treatment remains a viable alternative to operative intervention in selected lumbar burst fracture patterns.

Comparison of operative versus nonoperative treatment of lumbar burst fractures.

Back Pain in Postoperative Idiopathic Scoliosis: Long-Term Follow-Up Study (Abstract)

Twenty-two patients with major lumbar or thoracolumbar curves were treated with Zielke's modification of the Dwyer instrumentation, termed the "ventral derotation spondylodesis (VDS) system In 16 patients, this was followed by planned second-stage posterior Harrington instrumentation and fusion Six patients with adolescent idiopathic scoliosis were treated with VDS instrumentation and fusion alone In neuromuscular and adult idiopathic scoliosis, a combined approach resulted in excellent curve correction and a high rate of successful fusion In adolescent idiopathic scoliosis, VDS instrumentation alone resulted in excellent curve correction while permitting a shorter fusion length than conventional posterior Harrington instrumentation

Ventral derotation spondylodesis. A review of 22 cases.

Halm-Zielke instrumentation (HZI) was developed to eliminate the disadvantages of Zielke instrumentation (VDS) in terms of lack of primary stability and a kyphogenic effect. HZI is an anterior double-rod system. The system is composed of a lid-plate, which is fixed at the lateral aspect of the vertebral body with two screws, a sunk screw anteriorly and a VDS screw posteriorly. The lid-plate design provides the lowest possible implant profile. The longitudinal components consist of a threaded VDS rod and a solid, fluted rod. Correction is performed with the threaded rod and the solid rod. The solid rod allows internal derotation and relordosation, eliminates the Zielke three-point lever system and augments the system. The fluted design of the rod provides rotatory stability. This is a report of the first ten consecutive adolescent idiopathic scoliosis patients in a prospective clinical trial using HZI with a minimum follow-up of 2 years. Curves ranged from 36° to 77°. Correction of the frontal plane averaged 77.5% and 72.2% postoperatively and at follow-up, respectively. Thoracolumbar kyphosis was present in three patients and corrected in all from an average of + 18° to +1.7° at follow-up. Implant-related complications were not observed. All patients were treated without any additional external immobilization. In our opinion, HZI is a major improvement on the original Zielke VDS. It eliminates the kyphogenic effect and provides primary stability.

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Halm-Zielke instrumentation for primary stable anterior scoliosis surgery: operative technique and 2-year results in ten consecutive adolescent idiopathic scoliosis patients within a prospective clinical trial

Donald P. K. Chan

Papers

Lumbosacral transitional vertebrae and their relationship with lumbar extradural defects.

Comparison of operative versus nonoperative treatment of lumbar burst fractures.

Back Pain in Postoperative Idiopathic Scoliosis: Long-Term Follow-Up Study (Abstract)

Ventral derotation spondylodesis. A review of 22 cases.

Halm-Zielke instrumentation for primary stable anterior scoliosis surgery: operative technique and 2-year results in ten consecutive adolescent idiopathic scoliosis patients within a prospective clinical trial