Kristin E. Kean

Thoracic pedicle screw instrumentation: the learning curve and evolution in technique in the treatment of adolescent idiopathic scoliosis.

Study Design. Retrospective review. Objective. The purpose of this study is to evaluate the learning curve and associated evolution in surgical technique with thoracic pedicle screw instrumentation in adolescent idiopathic scoliosis (AIS). Summary of Background Data. Common treatment for AIS now includes posterior spinal fusion, using thoracic pedicle screws (TPS). It is critical to assess the efficacy, safety profile, and learning curve associated with this technique as its use becomes more widespread among inexperienced surgeons. Methods. Retrospective review of the senior author’s first 96 TPS cases for Lenke Type I AIS curves. Multiple regression techniques were used to discern whether increasing case number (CN) was associated with improved perioperative and 2-year minimum radiographic and clinical outcomes. The 96 cases were divided into 4 equal quartiles of 24 cases/group (i.e., Q1–Q4) and compared using analysis of variance measures. Results. A total of 1169 thoracic pedicle screws were placed in 96 patients. We found a significant correlation between CN and major curve correction at 2 years (P < 0.0001), inverse correlation between CN and length of stay (P = 0.02), and estimated blood loss (P = 0.03), but no differences in cell saver or complications. Univariate analysis revealed significant inverse correlations between increasing CN and transfusion rate (P = 0.02) and operative times (P = 0.0001). Total number of screws placed (Q1:9.4 vs. Q4:16.2, P < 0.0001) and number of screws/level (Q1:0.98 vs. Q4:1.64, P < 0.0001) increased linearly with increasing CN, whereas the average time for screw placement (Q1:24.2 vs. Q4:11.4 minutes, P < 0.0001) and ability to maintain T2–T12 kyphosis decreased (Q1:0.21 vs. Q4:−5.5 P = 0.02) with increasing CN. Conclusion. There is a significant learning curve associated with thoracic pedicle screw placement in AIS. We describe several technical steps that can be taken to increase the safety of screw placement at the beginning of the learning curve. Inexperienced surgeons should expect a gradual improvement over time in radiographic and clinical outcomes.

Low-density versus high-density thoracic pedicle screw constructs in adolescent idiopathic scoliosis: do more screws lead to a better outcome?

BACKGROUND CONTEXT Thoracic pedicle screw (TPS) constructs have improved curve correction measurements compared with hook and hybrid constructs in the treatment of adolescent idiopathic scoliosis (AIS), but the optimal implant density, or the number of screws per level, remains unknown in the treatment of flexible thoracic curves. PURPOSE To determine how implant density affects clinical outcome, radiographic outcome, and cost in the treatment of Lenke Curve Type I AIS. STUDY DESIGN A retrospective clinical study. PATIENT SAMPLE Ninety-one consecutive AIS patients with Lenke Type I curves who underwent surgical correction with a minimum follow-up of 24 months. OUTCOME MEASURES Radiographic outcomes included assessment of preoperative and 2-year postoperative thoracic Cobb angle, T5-T12 kyphosis, and curve flexibility. We also assessed SRS-22 outcome measures and thoracic angle of trunk rotation (ATR) before surgery and at the 2-year postoperative time point. The cost of each construct was also evaluated. METHODS Bivariate analysis was conducted between implant density and the following factors: percent correction of the major curve, ATR, and change in kyphosis. The correlation between curve flexibility and percent correction of the major curve was determined. Patients were then divided into two groups: the low-density (LD) TPS group defined by implant density below the mean number of screws per level for the entire cohort (less than 1.3 screws per level) and the high-density (HD) TPS group defined by implant density above the mean number of screws per level (more than 1.3 screws per level). Independent sample t tests were used to compare demographic data as well as radiographic and clinical outcomes at baseline and at follow-up between the two groups. RESULTS Sixty-one female and 30 male patients met inclusion criteria. No significant correlations were found between implant density and the following parameters: percent correction of the major curve (p=.25), ATR (p=.75), and change in T5-T12 kyphosis (p=.40). No correlation was found between curve flexibility and percent correction of the major curve (p=.54). The LD group consisted of 57 patients, whereas the HD group had 34 patients. There were no differences between the HD group and the LD group in regard to major curve correction, change in T5-T12 kyphosis, or change in ATR. Total implant costs were significantly higher in the HD group (

Video-assisted thoracoscopic spinal fusion compared with posterior spinal fusion with thoracic pedicle screws for thoracic adolescent idiopathic scoliosis.

13,272 vs.

Perioperative Outcomes and Complications Related to Teaching Residents and Fellows in Scoliosis Surgery

10,819; p<.01). The SRS-22 image domain and overall score improved at 2 years within both groups, but there were no group differences in any of the SRS-22 domains or the overall score. CONCLUSIONS We identified no clinical, radiographic, perioperative, or complication-related advantage of constructs with higher TPS implant density in this patient cohort with flexible idiopathic scoliosis. Cost was significantly higher with HD constructs in comparison with LD constructs. Optimal implant density chosen by the surgeon should rely on a number of factors including curve magnitude and rigidity, bone density, and desired correction.

Video-assisted anterior thoracoscopic spinal fusion versus posterior spinal fusion: a comparative study utilizing the SRS-22 outcome instrument.

BACKGROUND Although the gold standard for the surgical treatment of thoracic adolescent idiopathic scoliosis has been posterior spinal fusion, video-assisted thoracoscopic surgery recently has become a viable alternative. In the treatment of structural thoracic curves, video-assisted thoracoscopic surgery has demonstrated outcomes equivalent to those of posterior spinal fusion with use of an all-hook or hybrid pedicle screw-hook construct. No study to date, however, has compared this technique with posterior spinal fusion with thoracic pedicle screws, which has become the current standard of care. METHODS A matched-pair analysis of thirty-four consecutive patients (seventeen pairs) undergoing either video-assisted thoracoscopic surgery or posterior spinal fusion with thoracic pedicle screws for the treatment of structural scoliosis was performed; the study included eight male and twenty-six female patients with an average age of 15.0 years. Pairs were matched according to curve type and magnitude, patient age, and sex. Clinical data, the results of the Scoliosis Research Society questionnaire, and radiographic data were collected preoperatively and at a minimum of two years postoperatively and were compared between the groups. RESULTS Video-assisted thoracoscopic surgery was associated with significantly increased operative times (mean, 326 compared with 246 minutes; p = 0.033) and reduced blood loss (mean, 371 compared with 1018 mL; p = 0.001), but there were no differences between the groups in terms of the transfusion rate (18% compared with 29%; p = 0.69) or the length of stay. The percentage correction of the major curve was 57.3% for the video-assisted thoracoscopic surgery group and 63.8% for the posterior spinal fusion group (p = 0.08). With the numbers available, no differences were detected in terms of the cephalad thoracic curve, caudad compensatory lumbar curve, coronal balance, thoracic kyphosis, lumbar lordosis, sagittal balance, end vertebra tilt angle, or angle of trunk rotation measurements preoperatively or at the time of the latest follow-up. The average number of fused levels was 5.9 in the video-assisted thoracoscopic surgery group and 8.9 in the posterior spinal fusion group (p < 0.001). Relative to the Cobb end vertebra, the most caudad instrumented vertebra was 0.81 level more cephalad in the video-assisted thoracoscopic surgery group as compared with the posterior spinal fusion group (p = 0.004). No significant differences were detected in any of the questionnaire outcomes at any time point. Although both groups experienced similar improvement from baseline in terms of pulmonary function at two years, the posterior spinal fusion group had significantly improved peak flow measurements (p = 0.04) in comparison with the video-assisted thoracoscopic surgery group. CONCLUSIONS For single thoracic curves of <70 degrees in patients with a normal or hypokyphotic thoracic spine, video-assisted thoracoscopic surgery can produce equivalent radiographic results, patient-based clinical outcomes, and complication rates in comparison with posterior spinal fusion with thoracic pedicle screws, with the exception that posterior spinal fusion with thoracic pedicle screws may result in better major curve correction. The potential advantages of video-assisted thoracoscopic surgery over posterior spinal fusion with thoracic pedicle screws include reduced blood loss, fewer total levels fused, and the preservation of nearly one caudad fusion level, whereas the disadvantages include increased operative times and slightly less improvement in pulmonary function.

Maximal pulmonary recovery after spinal fusion for adolescent idiopathic scoliosis: how do anterior approaches compare?

Study Design. Single-surgeon retrospective case series of 303 consecutive operative patients with idiopathic scoliosis (IS). Objective. The purpose of this study is to evaluate the perioperative outcomes in patients undergoing surgery for IS as a function of the experience level of the surgical assistant. Summary of Background Data. The experience level of the surgical assistant, who is often a resident or fellow, has never before been evaluated as an independent factor in predicting perioperative outcomes and morbidity in scoliosis surgery. We hypothesize that there is no difference in perioperative outcomes with varying experience level of the surgical assistant. Methods. We evaluated the clinical, radiographic, and operative records from 303 consecutive operative patients from consecutive patients with IS. Group I was comprised of residents or spine fellows as assistants (teaching service, n = 175), and Group II consisted of junior or senior attendings as assistants (private practice service, n = 128). Multivariable linear regression was used to evaluate the relationship between experience level of the assistant and curve correction, operative time, estimated blood loss (EBL), complications, transfusions, and length of stay. Results. In the posterior spinal fusion group (PSF, n = 164), there were no statistically significant differences in operative times between Groups I and II. Group I operative time was significantly increased, however, in patients undergoing anterior spinal surgery (ASF, P = 0.01), video-assisted thoracoscopic surgery (P = 0.0004), and combined anterior/posterior surgeries (ASF/PSF, P = 0.0063). There were no differences in EBL in ASF, video-assisted thoracoscopic surgery, or PSF surgeries, however, Group I had significantly higher EBL in the ASF/PSF group (P = 0.0016). No group differences were detected with respect to curve correction, transfusion rates, length of stay, or early complication rates. Conclusion. The experience level of surgical assistant had little bearing on perioperative morbidity or radiographic outcomes in scoliosis surgery. Marginally increased operative times and EBL, without an increase in transfusions or complications, is an acceptably safe tradeoff for educating orthopedic residents and fellows.

Anterior spinal fusion for thoracolumbar scoliosis: comprehensive assessment of radiographic, clinical, and pulmonary outcomes on 2-years follow-up.

Study Design. Retrospective, matched cohort. Objective. The purpose of this study was to compare the Scoliosis Research Societys Outcomes measures (SRS-22) scores, as well as radiographic outcomes of patients with adolescent idiopathic scoliosis who had a single thoracic structural curvature treated by either posterior spinal fusion (PSF) or video-assisted thoracoscopic (VATS) fusion. Summary of Background Data. To our knowledge, there has been no prior matched-pair study comparing outcomes between 2 different surgical approaches for the same curve type using the SRS-22 outcomes instrument. Methods. Patients were evaluated before surgery and at 2-year follow-up. A total of 52 patients with Lenke type I curvature were paired by age, gender, and major Cobb angle into 2 groups: PSF (8 men, 18 women, mean age 14.7, mean Cobb angle 48.7) and VATS (mean age 14.8, mean Cobb angle 49.1). All questionnaire scores were classified based on domains of activity, pain, self-image, mental health, satisfaction, and total scores. Results. The patients in the VATS group scored higher than the PSF group in the domains of self-image (P < 0.02), mental health (P < 0.03), and total score (P < 0.05), but not activity, pain, or satisfaction at 2 years. There was no difference in percent curve correction between the match-paired groups. Within-group analyses revealed that VATS patients experienced insignificant improvements compared with PSF in most SRS-22 domains and a trend toward significant overall mean score improvement (P = 0.06). Conclusion. Based on the SRS-22 questionnaire data, the VATS patients scored higher in the self-image, mental health, and total domains despite similar curve corrections. We hypothesize that this may be related to the smaller surgical scar and less invasive nature of VATS.

Disease severity and treatment in adolescent idiopathic scoliosis: the impact of race and economic status

Study Design. Retrospective analysis of prospectively collected data. Objective. To compare the relative rates of pulmonary recovery and maximal pulmonary function with surgical approach. Summary of Background Data. Anterior versus posterior spinal fusion (ASF, PSF) for the treatment of adolescent idiopathic scoliosis (AIS) has been debated. Although procedures that violate the chest wall may compromise pulmonary function, lung function continues to improve after surgery at variable rates depending upon surgical approach. Methods. We reviewed the medical records from one hundred fifty nine AIS patients (age 15.6 ± 2.2; 113 women; 46 men) treated with spinal fusion from 2003 to 2007 by a single surgeon. Forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and radiographic measurements were evaluated before surgery and at 1, 3, 6, 12, and 24-months follow-up on average. Four surgical groups were compared: PSF, ASF (open thoracoabdominal approach for thoracolumbar curvature), video-assisted thoracoscopic surgical release with instrumentation (VATS-I), and VATS with PSF. FEV1 and FVC were fitted to model to evaluate the immediate postoperative pulmonary function (Yo), maximal recovery (Plateau), and rate (K) of pulmonary improvement. Results. Patients in each surgical subgroup were as follows: PSF (Lenke 1: n = 50, Lenke 2,3: n = 20), ASF (Lenke 5, n = 35), VATS-I (Lenke 1 = 31, Lenke 3 = 1), and VATS + PSF (Lenke1: n = 9, Lenke 2–6: n = 13). Early postoperative pulmonary function was higher with ASF and PSF as compared to both VATS groups (P < 0.05). Comparing all curve types, VATS-I showed a small decline of absolute FEV1 compared to PSF at 2-years follow-up. Comparing thoracic curves, however, no differences in FEV1 or FVC were noted at 6 to 12 months until 2-years follow-up. The rate of recovery (K) was equivalent for all surgical approaches and curve types. Conclusion. Compared to ASF or PSF, VATS procedures showed an initial decline in pulmonary function, which resolved fully by 6- to 12-months follow-up. Modest declines in maximal pulmonary function with VATS-I were seen when comparing all curve types together but not when comparing Lenke 1 curves alone. VATS procedures for thoracic scoliosis and open approaches for thoracolumbar curve types were associated with minimal to no permanent deficits.

P105. Low-Density vs. High-Density Thoracic Pedicle Screw Constructs in Adolescent Idiopathic Scoliosis: Is More Better?

Background There is a continued role for anterior spinal fusion (ASF) in the treatment of thoracolumbar scoliosis. Despite numerous previous reports of ASF in the treatment of thoracolumbar scoliosis, no single study has simultaneously evaluated clinical, radiographic, and pulmonary function outcomes. Methods Retrospective review of 31 consecutive thoracolumbar adolescent idiopathic scoliosis patients (Lenke type 5) who underwent ASF by a single surgeon. Patient records were comprehensively assessed for Scoliosis Research Society (SRS)-22 score, apical trunk rotation, radiographic changes, and pulmonary function before surgery and at 2-years follow-up. Results Thoracolumbar/lumbar curve correction averaged from 45 to 11 degrees (74%) and spontaneous correction of thoracic curves averaged from 26 to 15 degrees (42%). Instrumented segment lordosis increased by 11 degrees, whereas proximal junction kyphosis increased by 3 degrees. No significant changes were noted in T2-T12 kyphosis, distal junctional kyphosis, T12-S1 lumbar lordosis, or coronal balance. Thoracolumbar apical trunk rotation improved from 12 to 3 degrees. Average SRS scores significantly improved from 3.9 to 4.4. SRS assessments of self-image and pain also improved significantly from 3.6 to 4.5 and from 4.1 to 4.6, respectively. Absolute and percent predicted forced vital capacity and forced expiratory volume in 1 second were unchanged. Two patients suffered mild intercostal neuralgia postthoracotomy. There were no other complications. Conclusions The thoracoabdominal anterior approach for thoracolumbar scoliosis facilitates excellent clinical and radiographic outcomes, minimal blood loss, powerful apical trunk rotation correction, relative maintenance of lordosis, relatively short fusion constructs, and improved SRS-22 performance, without significant pulmonary function impairment at 2 years. It continues to be an efficacious treatment for thoracolumbar scoliosis. Level of Evidence Level IV.