Kathy Blanke

Adolescent idiopathic scoliosis: A new classification to determine extent of spinal arthrodesis

Background: The lack of a reliable, universally acceptable system for classification of adolescent idiopathic scoliosis has made comparisons between various types of operative treatment an impossible task. Furthermore, long‐term outcomes cannot be determined because of the great variations in the description of study groups. Methods: We developed a new classification system with three components: curve type (1 through 6), a lumbar spine modifier (A, B, or C), and a sagittal thoracic modifier (-, N, or +). The six curve types have specific characteristics, on coronal and sagittal radiographs, that differentiate structural and nonstructural curves in the proximal thoracic, main thoracic, and thoracolumbar/lumbar regions. The lumbar spine modifier is based on the relationship of the center sacral vertical line to the apex of the lumbar curve, and the sagittal thoracic modifier is based on the sagittal curve measurement from the fifth to the twelfth thoracic level. A minus sign represents a curve of less than +10°, N represents a curve of 10° to 40°, and a plus sign represents a curve of more than +40°.Five surgeons, members of the Scoliosis Research Society who had developed the new system and who had previously tested the reliability of the King classification on radiographs of twenty‐seven patients, measured the same radiographs (standing coronal and lateral as well as supine side-bending views) to test the reliability of the new classification. A randomly chosen independent group of seven surgeons, also members of the Scoliosis Research Society, tested the reliability and validity of the classification as well. Results: The interobserver and intraobserver kappa values for the curve type were, respectively, 0.92 and 0.83 for the five developers of the system and 0.740 and 0.893 for the independent group of seven scoliosis surgeons. In the independent group, the mean interobserver and intraobserver kappa values were 0.800 and 0.840 for the lumbar modifier and 0.938 and 0.970 for the sagittal thoracic modifier. These kappa values were all in the good-to-excellent range (>0.75), except for the interobserver reliability of the independent group for the curve type (kappa = 0.74), which fell just below this level. Conclusions: This new two-dimensional classification of adolescent idiopathic scoliosis, as tested by two groups of surgeons, was shown to be much more reliable than the King system. Additional studies are necessary to determine the versatility, reliability, and accuracy of the classification for defining the vertebrae to be included in an arthrodesis.

An analysis of sagittal spinal alignment in 100 asymptomatic middle and older aged volunteers.

Study Design. A radiographic evaluation of 100 adult volunteers over age 40 and without a history of significant spinal abnormality was done to determine indices of sagittal spinal alignment. Objectives. To determine the sagittal contours of the spine in a population of adults older than previously reported in the literature and to correlate age and overall sagittal balance to other measures of segmental spinal alignment. Summary of Background Data. Previous studies of sagittal alignment have focused on adolescent and young adult populations before the onset of degenerative changes that may affect sagittal alignment. Methods. Radiographic measurements were collected and subjected to statistical analysis. Results. Mean sagittal vertical axis fell 3.2 ± 3.2 cm behind the front of the sacrum. Total lumbar lordosis (T12‐S1) averaged −64° ± 10°. Lordosis increased incrementally with distal progression through the lumbar spine. Lordosis at L5‐S1 and the position of the apices of the thoracic and lumbar curves were most closely correlated to sagittal vertical axis. Increasing age correlated to a more forward sagittal vertical axis with loss of distal lumbar lordosis but without an increase in thoracic or thoracolumbar kyphosis. Conclusions. The majority of asymptomatic individuals are able to maintain their sagittal alignment despite advancing age. Loss of distal lumbar lordosis is most responsible for sagittal imbalance in those individuals who do not maintain sagittal alignment. Spinal fusion for deformity should take into account the anticipated loss of lordosis that may occur with age.

Comparative analysis of pedicle screw versus hook instrumentation in posterior spinal fusion of adolescent idiopathic scoliosis.

Study Design. A retrospective matched cohort study. Objective. To comprehensively compare the 2-year postoperative results of posterior correction and fusion with segmental pedicle screw instrumentation versus with hybrid (proximal hooks and distal pedicle screws) constructs in adolescent idiopathic scoliosis (AIS) treated at a single institution. Summary of Background Data. Despite the reports of satisfactory correction and maintenance of scoliotic curves by pedicle screw instrumentation, there have been no reports on the comprehensive comparison of AIS treatment after segmental pedicle screw instrumentation versus hybrid instrumentation. Materials and Methods. A total of 58 AIS patients that underwent posterior fusion with hybrid instrumentation (29) or pedicle screw (29) instrumentation at a single institution were sorted and matched according to four criteria: similar patient age, fusion levels, identical Lenke curve type, and identical operative methods. Patients were compared at 2-year follow-up according to radiographic changes, operative time, intraoperative blood loss, pulmonary function tests, and SRS-24 outcome scores. Results. The two cohorts were well matched. The preoperative major Cobb angle averaged 62° in the screw group and 60° in the hybrid group. Average major curve correction was 70% in the screw group and 56% in the hybrid group (P = 0.001). At 2-year follow-up, major curve correction was 65% and 46%, respectively (P < 0.001). At 2-year follow-up, thoracic sagittal Cobb angle changes between T5 and T12 were 9.0° decrease in the screw group and 2.4° decrease in the hybrid group compared with preoperative (P = 0.024). There were no differences in the lowest instrumented vertebra below the lower end vertebra (P = 0.56), operative time (P = 0.14), and average estimated blood loss (P = 0.54). Two years following surgery, the screw group demonstrated improved percent predicted pulmonary function values compared with that of the hybrid group (FVC; 81% → 81% in screw group vs. 85% → 79% in hybrid group P = 0.08, FEV1; 73% → 79% in screw group vs. 79% → 75% in hybrid group, P = 0.006). Postoperative total SRS-24 scores were similar in both groups (hybrid group: 99 vs. screw group: 95) (P = 0.19). There were no neurologic complications related to hybrid or pedicle screw instrumentation. Conclusion. Pedicle screw instrumentation offers a significantly better major curve correction and postoperative pulmonary function values without neurologic problems compared with hybrid constructs. Both instrumentation methods offer similar junctional change, lowest instrumented vertebra, operative time, and postoperative SRS-24 outcome scores in the operative treatment of AIS.

Pedicle subtraction osteotomy for the treatment of fixed sagittal imbalance

Background: Fixed sagittal imbalance (a syndrome in which the patient is only able to stand with the weight-bearing line in front of the sacrum) has many etiologies. The most commonly reported technique for correction is the Smith-Petersen osteotomy. Few reports on pedicle subtraction procedures (resection of the posterior elements, pedicles, and vertebral body through a posterior approach) are available in the peer-reviewed literature. We are aware of no report involving a substantial number of patients with coexistent scoliosis who underwent pedicle/vertebral body subtraction for the treatment of fixed sagittal imbalance. Methods: Twenty-seven consecutive patients in whom sagittal imbalance was treated with lumbar pedicle subtraction osteotomy at one institution were analyzed. Radiographic analysis included assessment of thoracic kyphosis, lumbar lordosis, lordosis through the pedicle subtraction osteotomy site, and the C7 sagittal plumb line. Outcomes analysis was performed with use of a before-and-after pain scale, items from the Oswestry questionnaire, and the Scoliosis Research Society (SRS) questionnaire after a minimum duration of follow-up of two years. Complications and radiographic findings were also analyzed for the entire group. Results: Overall, the average increase in lordosis was 34.1° and the average improvement in the sagittal plumb line was 13.5 cm. One patient had development of a lumbar pseudarthrosis through the area of pedicle subtraction osteotomy, and six patients had development of a thoracic pseudarthrosis. Two patients had development of increased kyphosis at L5/S1, caudad to the fusion, resulting in some loss of sagittal correction. There were significant improvements in the overall Oswestry score (p < 0.0001) and the pain-scale score (p = 0.0002). Most patients reported improvement in terms of pain and self-image as well as overall satisfaction with the procedure. Conclusions: Pedicle subtraction osteotomy is a useful procedure for patients with fixed sagittal imbalance. A worse clinical result is associated with increasing patient comorbidities, pseudarthrosis in the thoracic spine, and subsequent breakdown caudad to the fusion. Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

Complications and Outcomes of Pedicle Subtraction Osteotomies for Fixed Sagittal Imbalance

Study Design. Radiographic analysis, outcomes analysis (pain scale, Oswestry, SRS-24), and accumulation of complications. Outcomes and complications collected prospectively. Radiographic analysis performed retrospectively. Objectives. To assess the benefits and stress complications of pedicle subtractions osteotomies for patients with fixed sagittal imbalance. Summary of Background Data. Few reports on pedicle subtraction osteotomies exist in the peer-review literature for conditions other than trauma and ankylosing spondylitis. Materials and Methods. Thirty-three consecutive patients with sagittal imbalance treated with lumbar pedicle subtraction osteotomy at one institution (minimum 2-year follow-up) were analyzed. Complications were also analyzed for the entire group of consecutive pedicle subtraction osteotomies done at our institution to date (n = 66). Results. For the 33 patients with minimum 2-year follow-up, there were significant improvements in the overall Oswestry score (P 0.0001) and pain score (P = 0.0001). Most patients reported improvement in pain and self-image and reported overall satisfaction based on ultimate SRS-24 questionnaire. There was one pseudarthrosis in the lumbar spine through an area of pedicle subtraction osteotomy (area of previous laminectomy and nonunion), and six patients had thoracic pseudarthroses (levels other than the osteotomy level) and one patient had a pseudarthrosis at L5-S1. Two patients had acute angular kyphosis at the thoracolumbar junction at the proximal end of the construct. Five patients who experienced transient neurologic deficits resolved their deficits after central canal enlargement. Conclusions. The clinical result with pedicle subtraction osteotomy is reduced with pseudarthrosis in the thoracic or lumbar spine and subsequent breakdown adjacent to the fusion. For patients with a degenerative sagittal imbalance etiology the results were worse and the complications were higher. Central canal enlargement is critical.

Complications and predictive factors for the successful treatment of flatback deformity (fixed sagittal imbalance).

STUDY DESIGN This is an analysis of consecutive cases of flatback deformity (fixed sagittal imbalance), treated by one of two surgeons at a university hospital. OBJECTIVE To define factors that contribute to results with treatment of flatback syndrome, classify types of sagittal deformities, and discuss complications. SUMMARY OF BACKGROUND DATA There are few reports that detail the results and complications of current instrumentation and osteotomy techniques for correction of fixed sagittal deformities. METHODS Twenty-eight patients treated with osteotomies for sagittal imbalance were eligible for 2-year minimum follow-up (average, 3.6 years). Patients were classified (segmental imbalance, Type 1; or global imbalance, Type 2) and evaluated by upright radiographs, chart review, and a questionnaire. RESULTS Twenty-eight (100%) patients returned the questionnaire, and 28 had current radiographs. Five treatment groups were evaluated based on osteotomy type (anterior, posterior [Smith-Petersen], both, or pedicle subtraction) and use of anterior structural grafting. All patients were treated with modern bilateral hook-rod-screw constructs. Mean correction at the osteotomy levels was 25 degrees for Type 1 deformities and 30 degrees for Type 2 (P < 0.05). Sagittal correction averaged 6.6 cm in Type 2 deformities (P < 0.05). Questionnaire analysis showed a significant and persistent reduction in subjective pain level. There were seven patients with 11 total complications and no neurologic deficits. Associations among patients who were not satisfied with their results (n = 4) included insufficient sagittal correction (P = 0.045), pseudarthrosis (P = 0.045), coronal imbalance, and four or more medical comorbidities (P = 0.03). CONCLUSIONS Satisfaction with the results of treatment may be reduced in patients with four or more major co-existent medical problems, insufficient sagittal correction, and resultant pseudarthrosis.

Anterior fresh frozen structural allografts in the thoracic and lumbar spine. Do they work if combined with posterior fusion and instrumentation in adult patients with kyphosis or anterior column defects

Study Design. This was a prospective study of 24 adult patients with kyphosis or anterior column spinal defects treated with anterior fresh frozen allograft for anterior column defects and posterior instrumentation and autogenous grafting. Objectives. The objectives of the study were to assess the effectiveness of the anterior allograft in maintaining sagittal correction and to assess anterior incorporation. Summary of Background Data. Twenty‐four patients were followed for a minimum of 2 years (range, 2 + 0‐5 + 4 years). Methods. Upright radiographs were analyzed before surgery, immediately after surgery, and at the final follow‐up examination to assess success of anterior fusion and maintenance of correction. A strict four‐point grading system was used. Two independent observers analyzed the radiographic results. Results. Only two patients showed some collapse of their anterior allograft. The other 22 patients maintained correction, attaining a Grade I or Grade II fusion. Semiconstrained instrumentation was used posteriorly in the two patients who had graft collapse. Conclusions. Anterior structural allograft worked effectively to maintain correction of kyphosis if combined with posterior instrumentation and autogenous grafting. Rigid forms of posterior instrumentation were preferred.

Cotrel-dubousset instrumentation for adolescent idiopathic scoliosis.

We evaluated the results of segmental fixation of the spine with Cotrel-Dubousset instrumentation in ninety-five patients who had adolescent idiopathic scoliosis. The instrumentation was used in an attempt to achieve three-dimensional correction of the scoliosis, maintain lumbar lordosis, create thoracic kyphosis, and avoid the need for a postoperative cast or brace. The patients were followed for twenty-four to sixty-four months (average, thirty-five months). Cotrel-Dubousset instrumentation provided an average correction of the coronal curve of 48 per cent at the time of the most recent follow-up. The normal sagittal curves at the thoracolumbar junction and in the lumbar spine were maintained, and the thoracic kyphosis was increased slightly (average, +7 degrees). Apical translation improved an average of 60 per cent, and apical rotation improved an average of 11 per cent. Forced vital capacity improved an average of 21 per cent, and the one-second forced expiratory volume improved an average of 18 per cent. There were no major neurological deficits. A symptomatic pseudarthrosis developed in one patient. Postoperatively, decompensation of the spine developed in five of the first twenty-six patients who had a Type-II or Type-III curve. This complication was avoided in the last twenty-four patients who had a Type-II or Type-III curve by means of a stricter adherence to the definition of a Type-II curve, and reversal of the bend of the rod and the hooks between the caudal neutral and stable vertebrae. The major advantages of Cotrel-Dubousset instrumentation are the stable fixation that is achieved and the preservation of segmental lumbar lordosis.

The use of pedicle screw fixation to improve correction in the lumbar spine of patients with idiopathic scoliosis. Is it warranted

Study Design. A retrospective assessment of coronal, sagittal, and axial correction using convex lumbar pedicle screw constructs compared with hook constructs in patients with idiopathic scoliosis. Objective. To determine if pedicle screw constructs can improve coronal, sagittal, and axial correction without increased complications and therefore warrant their use in the lumbar spine. Summary of Background Data. Although hooks have been the traditional fixation choice for posterior scoliosis correction of the lumbar spine, pedicle screws may offer advantages for improved correction of lumbar spinal deformity. Methods. Twenty‐two patients constituted Group A (hooks), in which 17 were double major and five were King Type IV curves. These patients had a minimum follow‐up period of 2 years and an average of one hook per lumbar fusion segment. Twenty‐two patients constituted Group B (screws), in which 20 were double major and two were King Type IV curves. These patients had a minimum follow‐up period of 2 years, and screw configuration consisted of pedicle fixation on the convex side for correction and at times on the concave side for fixation. Results. Pedicle screw fixation constructs had improved lumbar Cobb correction (P < 0.05), lowest instrumented vertebra tilt (P < 0.05), lowest instrumented vertebra translation (P < 0.01), and segmental sagittal alignment from T12 to lowest instrumented vertebra (P < 0.01). There was no significant change in axial rotation using either surgical method. Conclusions. The use of pedicle screw fixation on the convex portion of the lumbar spine in patients with double major idiopathic scoliosis allows for improved correction of the lumbar Cobb measurement, horizontalization and translation of the lowest instrumented vertebra, and improved segmental lordization over the instrumented levels without increased complications.

Posterior Vertebral Column Resection for Severe Pediatric Deformity : Minimum Two-Year Follow-up of Thirty-Five Consecutive Patients

Study Design. Retrospective review of a prospectively accrued patient cohort. Objective. The ability to treat severe pediatric spinal deformity through an all-posterior vertebral column resection (VCR) has obviated the need for a circumferential approach in both primary and revision settings. We examined indications, correction rates, and complications of this challenging procedure in the pediatric population. Summary of Background Data. Traditionally, severe pediatric spinal deformities were treated through a combined anterior/posterior spinal fusion. Methods. Between 2000 and 2005, 35 consecutive patients underwent a posterior-only VCR by 1 of 2 surgeons at a single institution. Patients were divided into 5 diagnostic categories: (1) severe scoliosis (S) (n = 2; mean, 115°; range, 79–150°; average flexibility, 12%); (2) global kyphosis (GK) (n = 3; mean, 101°; range, 91–113°; average flexibility, 16%); (3) angular kyphosis (AK) (n = 10; mean, 86°; range, 45–135°, average flexibility, 23%); (4) kyphoscoliosis (KS) (n = 8; mean kyphosis, 103°/scoliosis 87°; mean combined, 190°; range, 144–237°); (5) congenital scoliosis (CS) (n = 12; mean, 43°; range, 23–69°; average flexibility, 20%). There were 20 primary/15 revision surgeries. There were 20 one-level, 11 two-level, and 4 three-level resections. Results. The major curve correction averaged: Group S = 61°/51%, Group GK = 56°/55%, Group AK = 51°/58%, Group KS = 98°/54%, and Group CS = 24°/60%. The average OR time was 460 minutes (range, 210–822), with an average EBL of 691 mL (range, 125–2200). There were no spinal cord-related complications; however, 2 patients (8.5%) lost intraoperative neuromonitoring data during correction with data returning to baseline following prompt surgical intervention. Two patients had implant revisions, 1 for a delayed deep infection at 2 years and the other for implant prominence at 3-year follow-up. Conclusion. A posterior-based VCR is a safe but challenging technique to treat severe primary or revision pediatric spinal deformities. Intraoperative SCM (especially motor-evoked potentials) is mandatory to prevent spinal cord-related neurologic complications. Dramatic radiographic and clinical correction of these deformities can be obtained via a posterior-only approach.