Anterior single-rod instrumentation of the thoracic and lumbar spine: saving levels

Incidence and risk factors of distal adjacent disc degeneration in adolescent idiopathic scoliosis patients undergoing fusion surgery: a systematic review and meta-analysis

PURPOSE

The objective of this meta-analysis was to determine the incidence of disc degeneration in patients with surgically treated adolescent idiopathic scoliosis (AIS) and identify the associated risk factors.

METHODS

PubMed, EMBASE, Scopus, and Cochrane Collaboration Library databases were searched. The outcomes of interest were the incidence of disc degeneration, SRS-22, and radiological risk factors. The lower instrumented vertebra (LIV) was also evaluated. Fixed effects were used if there was no evidence of heterogeneity. Statistical analysis was performed using Review Manager.

RESULTS

A meta-analysis was conducted including nine studies with a total of 565 patients. The analysis revealed that the global incidence of intervertebral disc degeneration in patients with surgically treated AIS patients was 24.78% (95% CI 16.59-32.98%) 10 years after surgery, which significantly increased to 32.32% (95% CI 21.16-43.47% at an average of 13.8 years after surgery. Among patients with significant degenerative disc changes, the SRS-22 functional, self-image, and satisfaction domains showed significantly worse results (MD - 0.25, 95% CI - 0.44 to - 0.05; MD - 0.50, 95% CI - 0.75 to - 0.25; and MD - 0.34, 95% CI - 0.66 to - 0.03, respectively). Furthermore, instrumentation at or above the L3 level was associated with a lower incidence of intervertebral disc degeneration compared to instrumentation below the L3 level (OR 0.25, 95% CI 0.10-0.64). It was also found that the preoperative and final follow-up lumbar curve magnitudes (MD 8.11, 95% CI 3.82-12.41) as well as preoperative and final follow-up lumbar lordosis (MD 0.42, 95% CI - 3.81 to 4.65) were associated with adjacent disc degeneration.

CONCLUSIONS

This meta-analysis demonstrated that the incidence of intervertebral disc degeneration significantly increased with long-term follow-up using fusion techniques, reaching up to 32% when patients were 28 years of age. Incomplete correction of deformity and fusion of levels below L3, were identified as negative prognostic factors. Furthermore, patients with disc degeneration showed worse functional outcomes.

Prevalence of pleural injury in an extrapleural approach to adolescent idiopathic scoliosis and association of pleural injury with postoperative respiratory function

BACKGROUND

The prevalence of pleural injury during surgery for adolescent idiopathic scoliosis using an extrapleural approach and the association of pleural injury with postoperative pulmonary function remain unclear. We sought to determine the prevalence of pleural injury associated with an extrapleural approach to adolescent idiopathic scoliosis, and to determine any difference in respiratory function between patients with or without pleural injury.

METHODS

Data from consecutive patients with scoliosis of the thoracolumbar/lumbar spine who underwent anterior spinal fusion using an extrapleural approach were assessed in this retrospective study. We had diagnosed and treated pleural injury according to our algorithm. Pre- and postoperative values of pulmonary function tests and postoperative change rates were compared between patients with and without pleural injury. FVC, %FVC, FEV1.0, and FEV1.0% were evaluated from pulmonary function tests.

RESULTS

We included data from 51 patients with adolescent idiopathic scoliosis (45 female and 6 male) with a mean age of 17.2 ± 3.5 years in this retrospective study. The group with pleural injury comprised 31 patients and the group without 20. Therefore, the prevalence of pleural injury during an extrapleural approach was 61%. We found no significant differences in preoperative FVC, %FVC, FEV1.0, and FEV1.0% between the groups. We found no significant differences in FVC, %FVC, FEV1.0, and FEV1.0% between the groups at 3 months or 1 year postoperatively. Furthermore, we found no significant differences in the postoperative change ratio of FVC, %FVC, FEV1.0, and FEV1.0% between the groups.

CONCLUSION

The prevalence of pleural injury associated with an extrapleural approach to scoliosis was 61%. Pleural injury was not associated with a decrease in postoperative pulmonary function in patients with scoliosis treated using an extrapleural approach.

Incidence and Predictive Factors of Shoulder Imbalance After Selective Anterior Spinal Fusion Surgery in Lenke Type 5C Adolescent Idiopathic Scoliosis

Background

No study has assessed the incidence or predictors of postoperative shoulder imbalance (PSI) in patients with Lenke type 5C adolescent idiopathic scoliosis (AIS) who underwent selective anterior spinal fusion (ASF). This study evaluated the incidence and predictors of shoulder imbalance after selective ASF for Lenke type 5C AIS.

Methods

In total, 62 patients with Lenke type 5C AIS (4 men and 58 women, mean age at surgery of 15.5 ± 1.5 years) were included and divided into the following two groups according to the radiographic shoulder height (RSH) at the final follow-up: PSI and non-PSI groups. All patients in this study underwent a whole-spine radiological evaluation. Various spinal coronal and sagittal profiles on radiographs were compared between the 2 groups. The clinical outcomes were assessed using the Scoliosis Research Society (SRS)-22 questionnaires.

Results

The mean final follow-up duration was 8.6 ± 2.7 years. PSI was observed in 10 patients (16.1%) immediately after surgery; however, in the long-term follow-up period, PSI improved in 3 patients spontaneously, whereas the remaining 7 patients had residual PSI. The preoperative RSH and correction rates of the major curve immediately after surgery or at the final follow-up were significantly larger in the PSI group than in the non-PSI group (p=.001, p=.023, and p=.019, respectively). Receiver operating characteristic curve analysis indicated that the cutoff values for preoperative RSH and the correction rates immediately after surgery and at the final follow-up were 11.79 mm (p=.002; area under the curve [AUC], 0.948), 71.0% (p=.026; AUC, 0.822), and 65.4% (p=.021; AUC, 0.835), respectively. No statistically significant difference was observed in the preoperative and final follow-up SRS-22 scores in any domain between the PSI and non-PSI groups.

Conclusions

Paying attention to the preoperative RSH and avoiding excessive correction of the major curve can prevent the occurrence of shoulder imbalance after selective ASF for Lenke type 5C AIS.

Selective Anterior Fusion Surgery Does Not Influence Global Spinal Sagittal Alignment in Lenke Type 5 Adolescent Idiopathic Scoliosis Patients

STUDY DESIGN

Retrospective comparative study.

OBJECTIVE

The aim of this study was to evaluate the changes in global spinal sagittal alignment (GSSA) following selective anterior spinal fusion (ASF) in patients with Lenke type 5 adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Few studies have assessed the changes in postoperative GSSA, including cervical, thoracic, and lumbosacral sagittal alignment in AIS patients with major thoracolumbar/lumbar (TL/L) curve who underwent selective ASF.

METHODS

Fifty-two patients with Lenke type 5 AIS (two males and 50 females, mean age at surgery of 16.4 ± 3.1 years) were included in this study. The average final follow-up was 8.3 ± 3.1 years after surgery. The variations of outcome variables were analyzed in various spinal sagittal profiles using radiographic outcomes (pre-operation, immediate post-operation, and final follow-up). The clinical outcomes at the final follow-up were assessed using Scoliosis Research Society (SRS)-22 and Oswestry Disability Index (ODI) questionnaires.

RESULTS

The mean Cobb angle of the main TL/L and minor thoracic curve was significantly improved after selective ASF, which was maintained up to the final follow-up. However, in all cases, the various sagittal parameters examined (sagittal vertical axis [SVA], C2-7 SVA, C2-7 lordosis, T1 slope, thoracic kyphosis, T10-L2 kyphosis, lumbar lordosis, pelvic incidence, pelvic tilt, and sacral slope), did not significantly change in the immediate postoperative period, and all GSSA parameters were maintained up to the final follow-up. Furthermore, the magnitude of coronal curve correction and fused levels did not affect each GSSA parameter postoperatively. During the period up to the final follow-up, no significant clinical symptoms were observed. The final SRS-22 global score was 4.5 ± 0.3, and ODI scored 0.8 ± 2.4.

CONCLUSION

Selective ASF did not influence various GSSA parameters postoperatively and could maintain excellent correction for coronal deformity with satisfactory final functional and clinical outcomes confirmed by long-term follow-up.Level of Evidence: 4.

Reducing the kyphosis effect of anterior short thoracolumbar/lumbar scoliosis correction with an autograft fulcrum effect

Background

Anterior scoliosis correction is a powerful technique with the disadvantage of a kyphotic effect on lumbar and thoracolumbar curves. We aimed to investigate whether a cognizant interposition of a rib graft anteriorly and at the concave side of the scoliotic curve causes significant fulcrum effect to enforce scoliosis correction and to reduce interfusional kyphosis in anterior scoliosis corrections.

Methods

Twenty otherwise comparable patients with lumbar and thoracolumbar adolescent idiopathic scoliosis (AIS) curves undergoing anterior short scoliosis correction with (n = 10) or without (n = 10, matched for age, gender and degree of deformity) fulcrum effect were retrospectively compared by means of radiographic measurements (sagittal and coronal profile, Cobb angles and intersegmental deformity correction angles) to evaluate the effect of this modified surgical technique.

Results

The overall amount of scoliosis correction was similar with 74 and 60% of initial curves of 57° and 53° in the case and control group respectively with a mean of 3 fused segments (4 screws).

Statistically relevant differences were found for intersegmental coronal cobb angles at the apex of 20° to 3° and 17° to 9° with and without fulcrum, respectively (p < 0.05). Creation of kyphosis in the fused segments was reduced with an interfusional kyphotic sagittal cobb angle of 15° pre-operatively vs. 3° post-operatively compared to the control group (13° pre-operatively vs. 18° post-operatively), (p < 0.05).

Conclusions

Interfusional hyperkyphosis associated with anterior scoliosis correction for thoracolumbar/lumbar curves can be reduced with cognizant positioning of the bone autograft at the antero-lateral (concave) site in the intervertebral region to create a fulcrum effect.

Trial registration

Registered at swissethics: BASEC No.: 2018–00180.

Feasibility of Single-Staged Bilateral Anterior Scoliosis Correction in Growing Patients

STUDY DESIGN

Retrospective analysis.

OBJECTIVES

The objective of this study was to analyze the feasibility of correcting double-curve scoliosis using dynamic scoliosis correction (DSC, also known as vertebral body tethering), which requires a bilateral anterior approach with deflation of both lungs. Typically, this approach falls under the exclusionary criteria for the eligibility for anterior scoliosis surgery. No data exists on the feasibility of single-staged bilateral DSC.

METHODS

A retrospective analysis was performed utilizing the data from 25 patients who underwent a bilateral anterior thoracic approach and instrumentation. Thirty-day postoperative complication rates were analyzed. A learning curve subanalysis was also performed to compare the first 12 patients to the remainder of the 13 patients, with a T-test (P ≤ .05).

RESULTS

Of the 25 patients treated, there was 1 intraoperative event: After performing lumbar DSC, the contralateral DSC was abandoned due to unexpected pleural scarring and staged selective thoracic fusion was performed. We observed 4 postoperative complications: 2 patients had recurrent pleural effusions, 1 patient was diagnosed with pneumonia, and 1 patient had a minor pulmonary embolism without cardiopulmonary consequences (after an international 24 hour flight). All patients recovered well. We observed a significant influence of learning curve on surgical time (328 vs 280 min, P = .03) and blood loss (480 vs 197 mL, P = .03).

CONCLUSION

Data suggests that bilateral, single-stage surgery for DSC is feasible albeit with an elevated complication rate that may partially attributable to the learning curve. Future research should focus on the cause of pulmonary complications and include a matched comparative analysis with traditional posterior fusion.

Hyper-Selective Posterior Fusion in Lenke 5C Adolescent Idiopathic Scoliosis: When Can We Stop Below the Upper End Vertebra?

STUDY DESIGN

A prospective analysis.

OBJECTIVE

To investigate whether the hyper-selective posterior fusion (upper instrumented vertebra [UIV] as the vertebra one level below the upper end vertebra [UEV], lower instrumented vertebra [LIV] as the lower end vertebra [LEV]) was applicable in posterior fusion of Lenke 5C adolescent idiopathic scoliosis (AIS) patients and what could be the indication of hyper-selective fusion.

SUMMARY OF BACKGROUND DATA

The improper UIV selection in selective fusion could lead to progressive thoracic compensatory curve, shoulder imbalance, and even coronal imbalance. However, few studies analyzed the clinical outcome of hyper-selective fusion.

METHODS

A prospective analysis of 80 patients with Lenke 5C AIS who underwent selective fusion was performed. According to the relationship between UEV and UIV, the patients were divided into UEV group (UIV = UEV) and UEV-1 group (UIV = UEV-1). Radiographic parameters and the incidence of postoperative proximal decompensation were compared. The Scoliosis Research Society (SRS)-22 scores were used to evaluate clinical outcomes between two groups.

RESULTS

Thirteen patients (27%) in UEV group and six (18.75%) in UEV-1 group showed proximal decompensation during follow-up, and the incidence was equivalent (P = 0.280). Within the UEV-1 group, the patients with proximal decompensation showed similar Risser grade, baseline thoracic Cobb angle, and main Cobb angle (P = 0.611, 0.435, 0.708, respectively). However, the baseline L-T apical vertebral translation (AVT) ratio was significantly larger in patients with proximal decompensation (P = 0.028). Meanwhile, patients with proximal decompensation in UEV group showed significantly smaller preoperative UIV translation and lumbar AVT but similar postoperative UIV tilt.

CONCLUSION

Hyper-selective posterior fusion strategy could be performed in Lenke 5C patients with Risser more than grade 2 and with thoracic compensatory curve over 15°. The UIV in patients with small baseline thoracic curve, represented by larger baseline lumbar-thoracic AVT ratio, should be selected as UEV to prevent proximal decompensation.

LEVEL OF EVIDENCE

4.

Anterior instrumented fusion for adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional deformity of the spine consisting of a lateral curvature, apical vertebral rotation, and an impairment of the sagittal profile. Surgical options include anterior and posterior approaches. Anterior instrumented fusion is suitable in Lenke type 1 and 5 curves. It supplies excellent results in coronal plane correction and is superior in the restoration of the sagittal profile and apical derotation. Fusion is shorter compared to posterior correction, and the complication rate is low. Pulmonary function is impaired postoperatively but recovers within a few years.

Long-Term Follow-Up of Anterior Spinal Fusion for Thoracolumbar/Lumbar Curves in Adolescent Idiopathic Scoliosis

STUDY DESIGN

Retrospective patient series analysis with update of long-term data.

OBJECTIVE

To define the long-term prognosis of the thoracolumbar/lumbar correction after selective anterior spinal fusion (ASF) in adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

The ASF is a well-described procedure for the treatment of AIS. The correction reliability over time, the consequences in adjacent spinal levels and patient's quality of life are fundamental for the characterization of AIS treatment.

METHODS

One hundred seven patients were submitted to single-rod ASF for thoracolumbar/lumbar (ThL/L) AIS between 1993 and 2016 in a single-surgeon experience. Seventy five were available for final follow-up evaluation 9 years ±4 (2-23) after surgery. A clinical and sequential radiographic evaluations were performed.

RESULTS

The mean age at surgery was 16 years ± 2.33 (14-20) and 94 (87%) were females. The mean final follow-up of the 75 patients available was 9 years ± 4 (2-23). Sixty-five patients had a Lenke type 5C curve and 10 had a type 6C curve. The mean values of the Scoliosis Research Society 22 (SRS-22) questionnaire in Lenke 5C was 92 ± 9 (71-109) and in Lenke 6C 90.3 ± 9 (75-107). In Lenke 5C group, the mean preoperative ThL Cobb angle was 38.4° ± 9.3 (21-60) and the postoperative was 5.9° ± 4.5 (0-18; P < 0.001) being similar at the final follow-up (P > 0.05). In Lenke 6C group, the mean preoperative ThL Cobb angle was 58.6° ± 13.9 (40-90) and the postoperative ThL Cobb was 22.6° ± 14.5 (5-48, P < 0.001) being similar at the final follow-up (P > 0.05). The mean preoperative Thoracic (Th) Cobb angle was 39° ± 7.6 (30-50), the postoperative was 30.6° ± 10.1 (14-49, P < 0.008) and in the final follow-up was 29.3° ± 10.7 (11-48, P < 0.011).

CONCLUSION

ASF is a safe procedure in the treatment of ThL/L with good long-term results and high rates of satisfaction among patients with AIS Lenke type 5C. The partial correction was frequent in Lenke type 6C despite the absence of progression in the non-instrumented curves.

LEVEL OF EVIDENCE

4.

Anterior Spinal Fusion and Posterior Spinal Fusion Both Effectively Treat Lenke Type 5 Curves in Adolescent Idiopathic Scoliosis: A Multicenter Study

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Retrospective comparison of radiographic and clinical outcomes between anterior spinal fusion (ASF) and posterior spinal fusion (PSF) in surgical treatment of Lenke 5 curves.

SUMMARY OF BACKGROUND DATA

ASF and PSF are used for treatment of Lenke 5 curves in patients with adolescent idiopathic scoliosis (AIS). Currently, no consensus exists for optimal surgical treatment of Lenke 5 curves.

METHODS

Patients with Lenke 5 curves treated with either ASF or PSF were prospectively enrolled in a multicenter database and then retrospectively reviewed. Demographic data, perioperative measures, radiographic data, and SRS-22R scores were collected and compared for statistical significance.

RESULTS

A total of 149 patients were included in the study; 51 underwent PSF and 98 underwent ASF. There was no difference in demographics between groups. The PSF group was fused one level longer than the ASF group (5.9 levels PSF, 4.6 levels ASF, p < .0001). The PSF group had shorter operative times (223 minutes PSF, 297 minutes ASF; p < .0001) and a higher proportion of patients who received a postoperative blood transfusion (45% vs. 5%, p < .0001). PSF patients had longer hospital stays (6.1d PSF vs. 5d ASF, p = .031). The ASF group had larger preoperative major curve (48.2° ASF, 44.2° PSF; p < .01). Coronal balance, thoracolumbar/lumbar Cobb angle, shoulder height, trunk shift, and overall sagittal balance were not different between groups at two-year follow-up. Curve correction at two-year follow-up was similar between groups (66% ASF vs. 62% PSF). There were no significant differences in clinical outcomes or complication rates between groups.

CONCLUSION

There is no difference in radiographic or clinical outcomes in patients treated with ASF or PSF for Lenke 5 curves. ASF may save a fusion level, but has longer operative time than PSF. Ultimately, the risks and benefits of each approach merit consideration by surgeon and patient.

LEVEL OF EVIDENCE

Level II.

Selective Anterior Thoracolumbar Fusion in Adolescent Idiopathic Scoliosis: Long-Term Results After 17-Year Follow-Up

STUDY DESIGN

Prospectively updated long-term data and retrospective case series analysis.

OBJECTIVE

To report the long-term results of selective anterior instrumented thoracolumbar (ThL) fusion in adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

The results of anterior selective fusion in AIS have been reported up to 2 and 5 years follow-up. However, there is a lack of evidence of long-term results of this surgical approach.

METHODS

Forty-two consecutive patients with main thoracolumbar/lumbar AIS who had undergone surgery for a selective anterior ThL instrumented fusion with more than 12 years of follow-up met inclusion criteria. Preoperative, postoperative (1-yr), and final updated radiographic parameters were recorded. Final ODI and SRS-22 questionnaires were evaluated.

RESULTS

Thirty-five patients were finally recruited (5 were lost and 2 refused). The mean age at surgery was 16.6 years. The mean final follow-up was 17.3 years (12-24 yr).The ThL preoperative Cobb was 49.5° ± 9, obtaining a postoperative correction of 79%±13 and final correction of 72% ± 18. The preoperative thoracic curve (31.4° ± 14.2) obtained a spontaneous postoperative correction to 18.4° ± 11.9, maintained at final follow-up (17.8° ± 10.8). Apical vertebral rotation improved from 25.8° ± 7.8 to 9.2° ± 5.5 and finally to 8° ± 5.2 (P = 0.001). Sagittal parameters (T5-T12 = 27.2° and L1-S1=56.9°) did not change significantly postoperatively nor by final follow-up. Coronal balance improved from 2.4 cm to 1.6 cm postoperatively and 0.8 cm at final follow-up (P = 0.006). The disc angulation below the last instrumented vertebra improved with follow-up from 7.6° to 5.7° (P = 0.012).There were no revision surgeries or infections. One patient showed a symptomatic lower disc degeneration requiring lumbar pain surgery. Final SRS-22 global score was 4.3/5. The final ODI scored 6/100.

CONCLUSION

In the long term, selective anterior thoracolumbar instrumentation with a single solid rod in AIS maintained good corrections on the three planes with no major complications or infections, no revision surgeries, and with satisfactory final functional and clinical outcomes.

LEVEL OF EVIDENCE

4.

Radiographic evaluation of posterior selective thoracolumbar or lumbar fusion for moderate Lenke 5C curves

INTRODUCTION

Posterior selective thoracolumbar or lumbar (TL/L) fusion with pedicle screw constructs for adolescent idiopathic scoliosis (AIS) has been studied in a few researches. However, few studies have discussed the indication for selective TL/L fusion and the behaviors of its adjacent disc angle. The present study aims to discuss the indication for posterior selective TL/L fusion and the behavior of the adjacent disc angle.

METHODS

45 consecutive cases of AIS undergoing posterior selective TL/L fusion were retrospectively evaluated, with an average follow-up of 36 months. Radiographs were reviewed to determine the coronal curve magnitude and the sagittal alignment preoperatively, postoperatively and at final follow-up. Thoracic curves in groups A had a correction loss of more than 5°, while thoracic curves in group B had a correction loss of not more than 5°.

RESULTS

The coronal curve magnitude of the TL/L curve averaged 44° preoperatively and it was corrected to 6° immediately with a correction rate of 84.8 %. At final follow-up it was 9° with a correction loss of 3°. The minor thoracic curve was 26° preoperatively, and the convex side bending curve magnitude averaged 8° with a flexibility of 72.7 %. It was corrected to 13° immediately with a spontaneous correction of 48.5 %. At final follow-up it was 14° with a correction loss of 1°. UIVA decreased from 4° to 2° after surgery, and it was 2° at final follow-up. LIVA decreased from 7° to 4° after surgery, and it was 5° at final follow-up. Maximal correction of TL/L curves in group A is significantly less than that in group B. 1 patient received revision surgery to fuse the progressive thoracic curve.

CONCLUSION

Posterior selective TL/L fusion with pedicle screw constructs allows for spontaneous thoracic correction and maintains coronal and sagittal balance during the follow-up. Maximal correction instead of undercorrection was recommended for moderate Lenke 5C curves. Disc wedging could be improved after surgery and well maintained during the follow-up.

Surgical treatment of Lenke 5 adolescent idiopathic scoliosis: Comparison of anterior vs posterior approach

AIM

To compare the posterior vs anterior approaches for fusion of Lenke 5 adolescent idiopathic scoliosis curves, matched for curve magnitude and for the distal level of fixation (dLOF) standardized to the third lumbar vertebrae (L3).

METHODS

A prospectively collected multicenter database was used for this retrospective comparative study. Our dependent variables included sagittal and coronal radiographic measurements, number of fused vertebrae, estimated blood loss, length of hospitalization and SRS total and individual domain scores at the two-year follow-up. Subject demographics were similar for all group comparisons. Independent t-test was used to compare groups for all analyses at P < 0.01.

RESULTS

For all matched cases of Lenke 5 curves, a selective approach was used only 50% of the time in cases undergoing a posterior fusion. When comparing a posterior selective approach to an anterior selective approach, surgeons utilizing a posterior approach fused significantly more levels than surgeons using an anterior approach with no other significant differences in radiographic or SRS outcomes (Ant = 4.8 ± 1.0 levels vs post = 6.1 ± 1.0 levels, P < 0.0001). When the dLOF was standardized to L3, the anterior approached provided significantly greater lumbar Cobb percent correction than the posterior approach (Ant = 69.1% ± 12.6% vs post = 54.6% ± 16.4%, P = 0.004), with no other significant radiographic or SRS score differences between approaches.

CONCLUSION

Surgeons treating Lenke 5c curves with a posterior instrumentation and fusion vs an anterior approach include more motion segments, even with a selective fusion. When controlled for the distal level of fixation, the anterior approach provides greater correction of the thoracolumbar curve.

Hemoptysis Due to Anterior Scoliosis Implants: A Case Report

CASE

A twenty-five-year-old man presented with recurrent episodes of hemoptysis requiring hospitalization and interventional embolization. Instrumentation that had been implanted ten years previously for anterior spinal correction and fusion to treat adolescent idiopathic scoliosis adjoined the medial border of the right lung. The instrumentation eroded the lung during respiration, which prompted the formation of adhesions and fibrosis. Because of the risk of additional hemoptysis events, we performed revision thoracotomy, removal of the spinal instrumentation, and partial lobectomy.

CONCLUSION

This rare and serious complication underscores the importance of meticulous surgical technique to ensure proper implant placement and of vigilant monitoring for late iatrogenic injury.

Comparison of Surgical Outcomes Between Anterior Fusion and Posterior Fusion in Patients With AIS Lenke Type 1 or 2 that Underwent Selective Thoracic Fusion -Long-term Follow-up Study Longer Than 10 Postoperative Years

STUDY DESIGN

A retrospective comparative study.

OBJECTIVE

We compared the outcomes between patients treated either by selective thoracic anterior (ASF) or posterior spinal fusion (PSF), with a minimum 10-year follow-up.

SUMMARY OF BACKGROUND DATA

A retrospective long-term follow-up study was conducted to compare PSF (P group) and ASF (A group) with Lenke type 1 or 2. There were no significant differences in the correction rate and incidence of degenerative discs (DDs) on the lumbar area. Loss of correction was greater in the A group.

METHODS

The inclusion criteria were female, AIS Lenke type 1 or 2, minimum 10-year follow-up, MRI check-up at 5 years and 10 years postop. The number of patients, age, and curve types at the time of surgery were matched in both groups. Complications, pulmonary function, and SRS-30 were also evaluated.

RESULTS

P group: adding-on (AO) occurred in 14 patients. Two patients demonstrated progression of scoliosis >5° during follow-up. Degenerative discs occurred in 43% of patients at 10 years postop. There were significant differences in the %VC and FVC before surgery and at the final visit (P < 0.05). A group: AO occurred in 16 patients. Eleven showed progression of scoliosis >5°. Degenerative disc was recognized in 53% of the patients. There was no significant difference in the pulmonary function. There was a significant difference in selfimage score in the SRS-30 between the two groups (P < 0.05).

CONCLUSION

Correction of scoliosis was significantly better ASF than PSF immediately postop. Greater loss of correction occurred with ASF at postop 10 years. Although shorter segments could be fused by ASF, there was no significant difference in the incidence of DDs. Pulmonary function test results improved in the P group and were restored in the A group during the perioperative period.

Partial Intervertebral Fusion Secures Successful Outcomes After Thoracoscopic Anterior Scoliosis Correction: A Low-Dose Computed Tomography Study

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVES

To analyze intervertebral (IV) fusion after thoracoscopic anterior spinal fusion (TASF) and explore the relationship between fusion scores and key clinical variables.

SUMMARY OF BACKGROUND INFORMATION

TASF provides comparable correction with some advantages over posterior approaches but reported mechanical complications, and their relationship to non-union and graft material is unclear. Similarly, the optimal combination of graft type and implant stiffness for effecting successful radiologic union remains undetermined.

METHODS

A subset of patients from a large single-center series who had TASF for progressive scoliosis underwent low-dose computed tomographic scans 2 years after surgery. The IV fusion mass in the disc space was assessed using the 4-point Sucato scale, where 1 indicates <50% and 4 indicates 100% bony fusion of the disc space. The effects of rod diameter, rod material, graft type, fusion level, and mechanical complications on fusion scores were assessed.

RESULTS

Forty-three patients with right thoracic major curves (mean age 14.9 years) participated in the study. Mean fusion scores for patient subgroups ranged from 1.0 (IV levels with rod fractures) to 2.2 (4.5-mm rod with allograft), with scores tending to decrease with increasing rod size and stiffness. Graft type (autograft vs. allograft) did not affect fusion scores. Fusion scores were highest in the middle levels of the rod construct (mean 2.52), dropping off by 20% to 30% toward the upper and lower extremities of the rod. IV levels where a rod fractured had lower overall mean fusion scores compared to levels without a fracture. Mean total Scoliosis Research Society (SRS) questionnaire scores were 98.9 from a possible total of 120, indicating a good level of patient satisfaction.

CONCLUSIONS

Results suggest that 100% radiologic fusion of the entire disc space is not necessary for successful clinical outcomes following thoracoscopic anterior selective thoracic fusion.

Adult thoracolumbar and lumbar scoliosis treated with long vertebral fusion to the sacropelvis: a comparison between new hybrid selective spinal fusion versus anterior-posterior spinal instrumentation

BACKGROUND CONTEXT

Combined anteroposterior spinal fusion with instrumentation has been used for many years to treat adult thoracolumbar/lumbar scoliosis. This surgery remains a technical challenge to spine surgeons, and current literature reports high complication rates.

PURPOSE

The purpose of this study is to validate a new hybrid technique (a combination of single-rod anterior instrumentation and a shorter posterior instrumentation to the sacrum) to treat adult thoracolumbar/lumbar scoliosis.

STUDY DESIGN

This study is a retrospective consecutive case series of surgically treated patients with adult lumbar or thoracolumbar scoliosis.

PATIENT SAMPLE

This is a retrospective study of 33 matched pairs of patients with adult scoliosis who underwent two different surgical procedures: a new hybrid technique versus a third-generation anteroposterior spinal fusion.

OUTCOME MEASURES

Preoperative and postoperative outcome measures include self-report measures, physiological measures, and functional measures.

METHODS

In a retrospective case-control study, 33 patients treated with the hybrid technique were matched with 33 patients treated with traditional anteroposterior fusion based on preoperative radiographic parameters. Mean follow-up in the hybrid group was 5.3 years (range, 2-11 years), compared with 4.6 years (range, 2-10 years) in the control group. Operating room (OR) time, estimated blood loss, and levels fused were collected as surrogates for surgical morbidity. Radiographic parameters were collected preoperatively, postoperatively, and at final follow-up. The Scoliosis Research Society Patient Questionnaire (SRS-22r) and Oswestry Disability Index (ODI) scores were collected for clinical outcomes.

RESULTS

Operating room time, EBL, and levels fused were significantly less in the hybrid group compared with the control group (p<.0001). The postoperative thoracic Cobb angle was similar between the hybrid and control techniques (p=.24); however, the hybrid technique showed significant improvement in the thoracolumbar/lumbar curves (p=.004) and the lumbosacral fractional curve (p<.0001). The major complication rate was less in the hybrid group compared with the control group (18% vs. 39%, p=.01). Clinical outcomes at final follow-up were not significantly different based on overall SRS-22r scores and ODI scores.

CONCLUSION

The new hybrid technique demonstrates good long-term results, with less morbidity and fewer complications than traditional anteroposterior surgery select patients with thoracolumbar/lumbar scoliosis. This study received no funding. No potential conflict of interest-associated bias existed.

Pulmonary function after less invasive anterior instrumentation and fusion for idiopathic thoracic scoliosis

Purpose

Standard thoracotomy for anterior instrumentation and fusion of the thoracic spine in idiopathic scoliosis may have detrimental effects on pulmonary function. In this study we describe a less invasive anterior surgical technique and show the pre- and postoperative pulmonary function with a minimum follow-up of 2 years.

Methods

Twenty patients with Lenke type 1 adolescent thoracic idiopathic scoliosis were treated with anterior spinal fusion and instrumentation. The mean preoperative Cobb angle of the thoracic curve was 53° ± 5.8. Pulmonary function tests (PFT) and radiographic evaluation was performed.

Results

The mean postoperative correction in Cobb angle of the thoracic curve was 27° ± 8.2 (49%).

The mean preoperative FEV1 was 2.81 ± 0.43 L, which increased to 3.14 ± 0.50 L at 2 years postoperatively (P = 0.000). The mean FEV1% did not change (89.60 ± 7.49% preoperatively, versus 90.53 ± 5.95% at 2 years follow-up, P = 0.467). The TLC increased from 4.62 ± 0.62 L preoperatively to 5.17 ± 0.63 L at 2 years follow-up (P = 0.000). The FEV1% at two years of follow-up improved to 104% of the FEV1% predicted value. The FEV1 improved to 97% of the FEV1 predicted value.

Conclusion

Anterior spinal fusion for idiopathic scoliosis by means of a minimal open thoracotomy proved to be a safe surgical technique that resulted in an improvement of pulmonary function. Our results are similar to those of thoracoscopic procedures reported in literature.

An FE investigation simulating intra-operative corrective forces applied to correct scoliosis deformity

Background

Adolescent idiopathic scoliosis (AIS) is a deformity of the spine, which may require surgical correction by attaching a rod to the patient’s spine using screws implanted in the vertebral bodies. Surgeons achieve an intra-operative reduction in the deformity by applying compressive forces across the intervertebral disc spaces while they secure the rod to the vertebra. We were interested to understand how the deformity correction is influenced by increasing magnitudes of surgical corrective forces and what tissue level stresses are predicted at the vertebral endplates due to the surgical correction.

Methods

Patient-specific finite element models of the osseoligamentous spine and ribcage of eight AIS patients who underwent single rod anterior scoliosis surgery were created using pre-operative computed tomography (CT) scans. The surgically altered spine, including titanium rod and vertebral screws, was simulated. The models were analysed using data for intra-operatively measured compressive forces – three load profiles representing the mean and upper and lower standard deviation of this data were analysed. Data for the clinically observed deformity correction (Cobb angle) were compared with the model-predicted correction and the model results investigated to better understand the influence of increased compressive forces on the biomechanics of the instrumented joints.

Results

The predicted corrected Cobb angle for seven of the eight FE models were within the 5° clinical Cobb measurement variability for at least one of the force profiles. The largest portion of overall correction was predicted at or near the apical intervertebral disc for all load profiles. Model predictions for four of the eight patients showed endplate-to-endplate contact was occurring on adjacent endplates of one or more intervertebral disc spaces in the instrumented curve following the surgical loading steps.

Conclusion

This study demonstrated there is a direct relationship between intra-operative joint compressive forces and the degree of deformity correction achieved. The majority of the deformity correction will occur at or in adjacent spinal levels to the apex of the deformity. This study highlighted the importance of the intervertebral disc space anatomy in governing the coronal plane deformity correction and the limit of this correction will be when bone-to-bone contact of the opposing vertebral endplates occurs.

Secondary curve behavior in Lenke type 1C adolescent idiopathic scoliosis after thoracoscopic selective anterior thoracic fusion

STUDY DESIGN

Analysis of a case series of 24 patients with Lenke 1C adolescent idiopathic scoliosis (AIS) receiving selective thoracoscopic anterior scoliosis correction.

OBJECTIVE

To report the behavior of the compensatory lumbar curve in a group of patients with Lenke IC AIS after thoracoscopic anterior scoliosis correction and to compare the results of this study with previously published data.

SUMMARY OF BACKGROUND DATA

Several prior studies have reported spontaneous lumbar curve correction for both anterior and posterior selective fusions in patients with Lenke 1C/King-Moe 2; however, to our knowledge no previous studies have reported outcomes of thoracoscopic anterior correction for this curve type.

METHODS

All patients with AIS with a curve classification of Lenke 1C and a minimum of 24-month follow-up were obtained from a consecutive series of 190 patients with AIS who underwent thoracoscopic anterior instrumented fusion. Cobb angles of the major curve, instrumented levels, compensatory lumbar curve, and T5-T12 kyphosis were recorded, as well as coronal spinal balance, T1 tilt angle, and shoulder balance. All radiographical parameters were measured before surgery and at 2, 6, 12, and 24 months after surgery.

RESULTS

Twenty-four female patients with right thoracic curves had a mean thoracic Cobb angle of 53.0° before surgery, decreasing to 24.9° 2 years after surgery. The mean lumbar compensatory Cobb angle was 43.5° before surgery, spontaneously correcting to 25.4° 2 years after surgery, indicating balance between the thoracic and lumbar scoliotic curves. The lumbar correction achieved (41.8%) compares favorably to previous studies.

CONCLUSION

Selective thoracoscopic anterior fusion allows spontaneous lumbar curve correction and achieves coronal balance of main thoracic and compensatory lumbar curves, good cosmesis, and patient satisfaction. Correction and balance are maintained 24 months after surgery.

CT and radiographic analysis of sagittal profile changes following thoracoscopic anterior scoliosis surgery

Background

Previous studies report an increase in thoracic kyphosis after anterior approaches and a flattening of sagittal contours following posterior approaches. Difficulties with measuring sagittal parameters on radiographs are avoided with reformatted sagittal CT reconstructions due to the superior endplate clarity afforded by this imaging modality.

Methods

A prospective study of 30 Lenke 1 adolescent idiopathic scoliosis (AIS) patients receiving selective thoracoscopic anterior spinal fusion (TASF) was performed. Participants had ethically approved low dose CT scans at minimum 24 months after surgery in addition to their standard care following surgery. The change in sagittal contours on supine CT was compared to standing radiographic measurements of the same patients and with previous studies. Inter-observer variability was assessed as well as whether hypokyphotic and normokyphotic patient groups responded differently to the thoracoscopic anterior approach.

Results

Mean T5-12 kyphosis Cobb angle increased by 11.8 degrees and lumbar lordosis increased by 5.9 degrees on standing radiographs two years after surgery. By comparison, CT measurements of kyphosis and lordosis increased by 12.3 degrees and 7.0 degrees respectively. 95% confidence intervals for inter-observer variability of sagittal contour measurements on supine CT ranged between 5-8 degrees. TASF had a slightly greater corrective effect on patients who were hypokyphotic before surgery compared with those who were normokyphotic.

Conclusions

Restoration of sagittal profile is an important goal of scoliosis surgery, but reliable measurement with radiographs suffers from poor endplate clarity. TASF significantly improves thoracic kyphosis and lumbar lordosis while preserving proximal and distal junctional alignment in thoracic AIS patients. Supine CT allows greater endplate clarity for sagittal Cobb measurements and linear relationships were found between supine CT and standing radiographic measurements. In this study, improvements in sagittal kyphosis and lordosis following surgery were in agreement with prior anterior surgery studies, and add to the current evidence suggesting that anterior correction is more capable than posterior approaches of addressing the sagittal component of both the instrumented and adjacent non instrumented segments following surgical correction of progressive Lenke 1 idiopathic scoliosis.

Anterior short correction in thoracic adolescent idiopathic scoliosis with mini-open thoracotomy approach: prospective clinical, radiological and pulmonary function results

INTRODUCTION

This is a prospective study of adolescent patients in whom idiopathic thoracic scoliosis was corrected by short anterior fusion through a mini-open thoracotomy approach. Clinical, radiological and pulmonary function results of minimal 2-year (2-6) follow-up are presented.

MATERIALS AND METHODS

Consecutive 62 patients with Lenke 1 and 2 curves, having main thoracic scoliosis of up to 75°, were prospectively included. The shoulder imbalance in Lenke 2 patients was less than 20 mm. Thoracic scoliosis was corrected by short anterior fusion. The thoracic spine was exposed by an 8-cm mini-open thoracotomy incision. The operation technique and choosing of fusion levels are thoroughly described. Complete 360° discectomies and convex side vertebral endplates osteotomies are essential for deformity corrections with short fusions. Single-rod 5.5-mm titanium implants were used. The age at the time of operation was mean 15.2 years; 56 patients had a single thoracic curve and 6 patients had a double thoracic curve. There were almost equal numbers of patients with lumbar modifier A, B or C. The average length of fusion was 5.5 (4-7) vertebrae. The average length of fusion was 3.5 (2-6) vertebrae shorter than the average curve length.

RESULTS

The instrumented thoracic curves improved by 58.3% at 6 weeks and 56.3% at the last follow-up. Apex thoracic vertebral rotation improved by 73.78% at 6 weeks and 76.24% at the last follow-up. The non-instrumented upper thoracic curve improved by 25% in double thoracic scoliosis, where the mid-thoracic curve was selectively fused, and the non-instrumented lumbar curves improved by 33.9% at the last follow-up. The radiological changes from 6 weeks to the last follow-up were statistically not significant. The clinical rib hump improved by 54% at the last follow-up. There were no significant changes in the pulmonary function. FVC% was 81.04% preoperatively, 76.41% at 6 months and 80.38% at the 2-year follow-up. The results of SRS 24 questionnaire improved from a total of 61.40 points preoperatively to 100.50 points at 6 months and 98.62 points at the 2-year follow-up. There were no neurological or thoracotomy related complications, no pseudarthrosis, no implant pullout or breakage.

CONCLUSION

A good deformity correction without loss of correction or adding on, a good cosmetic result and good patient's satisfaction were achieved through shorter than end-to-end thoracic fusions. The radiological residual deformity is acceptable. Anterior correction of thoracic scoliosis with a short spinal fusion is recommended to keep the large part of the spine mobile. A very short fusion, small thoracotomy incision, low-profile implants and complete closure of parietal pleura are keys to prevent reduction in postoperative lung function.

A Kohonen neural network description of scoliosis fused regions and their corresponding Lenke classification

PURPOSE

Surgical instrumentation for adolescent idiopathic scoliosis (AIS) is a complex procedure where selection of the appropriate curve segment to fuse, i.e., fusion region, is a challenging decision in scoliosis surgery. Currently, the Lenke classification model is used for fusion region evaluation and surgical planning. Retrospective evaluation of Lenke classification and fusion region results was performed.

METHODS

Using a database of 1,776 surgically treated AIS cases, we investigated a topologically ordered self organizing Kohonen network, trained using Cobb angle measurements, to determine the relationship between the Lenke class and the fusion region selection. Specifically, the purpose was twofold (1) produce two spatially matched maps, one of Lenke classes and the other of fusion regions, and (2) associate these two maps to determine where the Lenke classes correlate with the fused spine regions.

RESULTS

Topologically ordered maps obtained using a multi-center database of surgically treated AIS cases, show that the recommended fusion region agrees with the Lenke class except near boundaries between Lenke map classes. Overall agreement was 88%.

CONCLUSION

The Lenke classification and fusion region agree in the majority of adolescent idiopathic scoliosis when reviewed retrospectively. The results indicate the need for spinal fixation instrumentation variation associated with the Lenke classification.

Pulmonary function changes after various anterior approaches in the treatment of adolescent idiopathic scoliosis

STUDY DESIGN

Prospective radiographic and chart review of pulmonary function in patients who underwent 3 different anterior spinal surgery approaches for adolescent idiopathic scoliosis (AIS).

OBJECTIVE

To assess the impact on pulmonary function in patients with AIS after anterior surgical approaches, including open thoracotomy, thoracoscopic with and without thoracoplasty, and thoracoabdominal 2 years after surgery.

SUMMARY OF BACKGROUND DATA

Potential advantages of anterior surgery in the treatment of AIS include saving of distal motion segments and improving kyphosis restoration in the thoracic spine, possibly at the cost of pulmonary function impairment. Although thoracoscopic spinal instrumentation and fusion has recently been shown to induce less pulmonary impairment compared with open thoracotomy, no study has evaluated the effect of thoracoplasty as an adjunct to thoracoscopic surgery, nor the effects of the thoracoabdominal approach for thoracolumbar curvature.

METHODS

A multicenter spinal deformity database was queried for patients who underwent an anterior approach for either Lenke I or Lenke V idiopathic scoliosis. There were 68 patients in the thoracotomy group, 44 in the thoracoscopic group, and 19 in the thoracoabdominal group. Absolute and percent-predicted values of forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and total lung capacity (TLC) were evaluated preoperatively and at 2-year follow-up, and comparisons were made within and between each group.

RESULTS

Comparing between groups at 2 years postoperatively, the thoracotomy group demonstrated significantly greater decreases (-10.97% and -12.97%) in both percent-predicted FEV1 and FVC, respectively, when compared with the thoracoscopic group (-4.40% and -4.73%), respectively. Percent-predicted TLC in the thoracoscopic group increased (3.19%), but decreased in the thoracotomy group (-8.00%). Subanalysis of the thoracoscopic group at 2 years revealed that the addition of a thoracoplasty (3 to 5 ribs) significantly reduced percent-predicted FEV1 (-11.6%, P = 0.0013) and percent-predicted FVC (-16.0%, P = 0.017) from baseline. Patients who underwent thoracoscopy alone without a thoracoplasty experienced no significant detrimental changes in these parameters at 2 years, and instead experienced significant increases in absolute TLC (P < 0.001) and percent-predicted TLC (P = 0.035). There were no significant changes demonstrated in the thoracoabdominal group for all 3 parameters.

CONCLUSIONS

Slight declines in pulmonary function at 2-year follow-up were noted in both the thoracotomy and thoracoscopic groups, but to a significantly greater extent in those with an open thoracotomy. Significantly greater impairment in pulmonary function was seen in thoracoscopic patients who underwent thoracoplasty, whereas those without thoracoplasty either had no significant declines at 2 years or experienced slight but significant improvement. No significant diminishment was noted for the thoracoabdominal approach, despite disruption of the diaphragm.

Long-term outcomes of anterior spinal fusion with instrumentation for thoracolumbar and lumbar curves in adolescent idiopathic scoliosis

STUDY DESIGN

A retrospective review of the long-term clinical and radiographic outcomes of anterior spinal fusion with instrumentation for thoracolumbar and lumbar curves in adolescent idiopathic scoliosis (AIS).

OBJECTIVE

To evaluate a group of patients based on Scoliosis Research Society (SRS)-30 and Oswestry data as well as radiographic and magnetic resonance imaging (MRI) and report the results of long-term follow-up of this surgical treatment for this particular curve pattern in AIS.

SUMMARY OF BACKGROUND DATA

Anterior spinal fusion with instrumentation has been used for many years in the treatment of thoracolumbar and lumbar curves in AIS. However, the long-term radiographic and functional outcomes of this procedure are not well known.

METHODS

During 1984 to 1995, 31 patients with the diagnosis of AIS underwent anterior spinal instrumentation and fusion for thoracolumbar or lumbar scoliosis at our institution. A retrospective review of this patient group was performed to evaluate patient satisfaction, functional outcome, curve progression, implant failure, and disc degeneration. Radiographs and lumbar MRIs were obtained along with SRS-30 Questionnaire and Oswestry Disability Index data.

RESULTS

Eighteen patients were available for review. Average follow-up for this study was 16.97 years. Based on SRS-30 and the Oswestry Disability Index data, most patients had good function scores and acceptable pain levels. Radiographs demonstrated no progression of the thoracolumbar or thoracic curves. Implant failure was identified in 2 patients. Radiographic changes of early degenerative disc disease were identified in most patients but had no correlation with SRS or Oswestry data. These degenerative changes were evident on both radiographs and MRI.

CONCLUSION

The anterior approach in the treatment of thoracolumbar and lumbar curves in AIS offers good long-term functional outcomes for patients. Despite expected degenerative changes, patients scored well on the SRS and Oswestry tests, and were able to pursue careers and family activities.

Interbody cage support improves reconstruction of sagittal balance after anterior selective fusion in Lenke type 5 idiopathic scoliosis patients

OBJECTIVE

To investigate the effect of interbody cage support on reconstruction of the sagittal profile after anterior selective correction in Lenke type 5 adolescent idiopathic scoliosis (AIS) patients.

METHODS

In this retrospective study, a total of 40 AIS patients with a Lenke type 5 curve who underwent anterior selective fusion (ASF) using a single rod were studied. They were divided into two groups: Group A, bone grafting with an interbody titanium mesh cage (TMC); and Group B, bone grafting without a TMC. There were 19 female and 1 male patient aged 12-18 years in Group A, and 17 female and 3 male patients aged 13-20 years in Group B. All patients were followed up for more than 18 months. The coronal correction of the scoliosis and reconstruction of the sagittal profile were evaluated retrospectively.

RESULTS

By final follow-up, more than 70% correction had been achieved for the primary curve and a spontaneous correction for the secondary curve in both groups. Satisfactory reconstructions on the sagittal plane were also observed. Similar changes were found in Group A and Group B, including increases in thoracic kyphosis, slight changes in thoracolumbar junctional kyphosis, no significant losses of lumbar lordosis, mild increases in proximal junctional measurement, and remarkable lordosis losses in the instrumented segments. With lessening of the sagittal balance and L(1) offset, a significant anterior shift of the C(7) plumb line was noted during follow-up in Group A, indicating a more balanced spine in this group.

CONCLUSION

Anterior selective single rod instrumentation and fusion is a recommended method for Lenke type 5C AIS. A structural interbody cage does not appear to improve the regional profile, nor the profiles in the instrumented area and the adjacent proximal and distal segments; yet could result in a better total balance in the long-term.

[Selective fusion of idiopathic scoliosis with respect to the Lenke classification]

Indications for surgical treatment of idiopathic scoliosis are progressive curves greater than 40-50 degrees. In most cases, fusion of only the primary (structural) curve(s) is sufficient due to the flexibility and spontaneous correction of the secondary curves. Therefore, it is crucial to identify both primary and secondary curves. According to the Lenke classification, all curves with a residual curve of more than 25 degrees on the bending films and those with a pathological kyphosis are regarded as structural and should be fused, whereas the nonstructural curves can be left unfused. However, according to reports in the literature and to the author's experience, clinical parameters such as shoulder level and rib or lumbar hump as well as radiometric criteria such as rotation are relevant as well. In summary, the Lenke classification is an important and helpful tool for analysing idiopathic curves and determining fusion length, even though each scoliosis case needs to be evaluated individually, especially taking clinical parameters into account.

Thoracoscopic anterior instrumented fusion for adolescent idiopathic scoliosis with emphasis on the sagittal plane

BACKGROUND CONTEXT

Anterior fusion through an open thoracotomy restores kyphosis more reliably than posterior techniques in patients with thoracic adolescent idiopathic scoliosis (AIS). Video-assisted thoracoscopic spinal fusion and instrumentation (VATS) minimizes the morbidity, from soft tissue and muscle dissection that accompanies traditional open thoracotomy. To our knowledge, there has not been a comprehensive analysis of VATS with respect to radiographic and clinical outcomes in the sagittal plane.

PURPOSE

To measure the radiographic and clinical outcomes after VATS with emphasis on the sagittal plane.

STUDY DESIGN/SETTING

A retrospective, radiographic review of 26 consecutive patients with Lenke type-I AIS who underwent VATS.

METHODS

Radiographs of 26 consecutive patients with Lenke type-I AIS curves operated by a single surgeon were retrospectively reviewed after VATS. Sagittal and coronal parameters were compared with reported data for open anterior and posterior procedures.

RESULTS

There was an increase in kyphosis from baseline to final follow-up by 6.6 degrees (25%) from T2 to T12 (p<.0001), 8.7 degrees (50%) from T5 to T12 (p<.0001), and 8 degrees (54%) in the instrumented segment (p<.0001). Junctional kyphosis did not occur. No differences were detected in sagittal measurements between the first postoperative erect and the final radiographs. Patients experienced significant improvements from baseline to 2 years in Scoliosis Research Society-22 Health-Related Quality-of-Life Outcome Questionnaire scores (p<.0001).

CONCLUSIONS

Video-assisted thoracoscopic spinal fusion and instrumentation, in agreement with results reported for open anterior instrumentation, reliably restores or increases thoracic kyphosis while preserving junctional alignment in thoracic AIS.

Radiographic outcomes over time after endoscopic anterior scoliosis correction: a prospective series of 106 patients

STUDY DESIGN

A prospective, consecutive series of 106 patients receiving endoscopic anterior scoliosis correction.

OBJECTIVE

To analyze changes in radiographic parameters and rib hump in the 2 years after surgery.

SUMMARY OF BACKGROUND DATA

Endoscopic anterior scoliosis correction is a level sparing approach and therefore, it is important to assess the amount of decompensation which occurs after surgery.

METHODS

All patients received a single anterior rod and vertebral body screws using a standard compression technique. Cleared disc spaces were packed with either mulched femoral head allograft or rib head/iliac crest autograft. Radiographic parameters (major, instrumented, minor Cobb, T5-T12 kyphosis) and rib hump were measured at 2, 6, 12, and 24 months after surgery. Paired t tests and Wilcoxon signed ranks tests were used to assess the statistical significant of changes between adjacent time intervals.

RESULTS

Mean loss of major curve correction from 2 to 24 months after surgery was 4 degrees. Mean loss of rib hump correction was 1.4 degrees. Mean sagittal kyphosis increased from 27 degrees at 2 months to 30.6 degrees at 24 months. Rod fractures and screw-related complications resulted in several degrees less correction than patients without complications, but overall there was no clinically significant decompensation after complications.

CONCLUSION

There are small changes in deformity measures after endoscopic anterior scoliosis surgery, which are statistically significant but not clinically significant.

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

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.

Surgical treatment of main thoracic scoliosis with thoracoscopic anterior instrumentation. a five-year follow-up study

BACKGROUND

The surgical outcomes in patients with scoliosis at two years following anterior thoracoscopic spinal instrumentation and fusion have been reported. The purpose of this study was to evaluate the results at five years.

METHODS

A consecutive series of forty-one patients with major thoracic scoliosis treated with anterior thoracoscopic spinal instrumentation was evaluated at regular intervals. Prospectively collected data included patient demographics, radiographic measurements, clinical deformity measures, pulmonary function, an assessment of intervertebral fusion, and the scores on the Scoliosis Research Society (SRS-24) outcomes instrument. Perioperative and postoperative complications were recorded. Patient data for the preoperative, two-year, and five-year postoperative time points were compared. In addition, a univariate analysis compared selected two-year radiographic, pulmonary function, and SRS-24 data of the study cohort and those of the patients lost to follow-up.

RESULTS

Twenty-five (61%) of the original forty-one patients had five-year follow-up data and were included in the analysis. Between the two-year and five-year follow-up visits, no significant changes were observed with regard to the average percent correction of the major Cobb angle (56% +/- 11% and 52% +/- 14%, respectively), average total lung capacity as a percent of the predicted value (95% +/- 14% and 91% +/- 10%), and the average total SRS-24 score (4.2 +/- 0.4 and 4.1 +/- 0.7). Radiographic evaluation of intervertebral fusion at five years revealed convincing evidence of a fusion with remodeling and trabeculae present at 151 (97%) of the 155 instrumented motion segments. No postoperative infections or clinically relevant neurovascular complications were observed. Rod failure occurred in three patients, and three patients required a surgical revision with posterior spinal instrumentation and fusion.

CONCLUSIONS

Thoracoscopic anterior instrumentation for main thoracic idiopathic scoliosis results in five-year outcomes comparable with those reported previously for open anterior and posterior techniques. The radiographic findings, pulmonary function, and clinical measures remain stable between the two and five-year follow-up time points. Thoracoscopic instrumentation provides a viable alternative to treat spinal deformity; however, the risks of pseudarthrosis, hardware failure, and surgical revision should be considered along with the advantages of limited muscular dissection and improved scar appearance.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

Biomechanical comparison of three fixation techniques for unstable thoracolumbar burst fractures. Laboratory investigation

OBJECT

Increased structural stability is considered sufficient justification for higher-risk surgical procedures, such as circumferential fixation after severe spinal destabilization. However, there is little biomechanical evidence to support such claims, particularly after traumatic lumbar burst fracture. The authors sought out to compare the biomechanical performance of the following 3 fixation strategies for spinal reconstruction after decompression for an unstable thoracolumbar burst fracture: 1) short-segment anterolateral fixation; 2) circumferential fixation; and 3) extended anterolateral fixation.

METHODS

Thoracolumbar spines (T10-L4) from 7 donors (mean age at death 64+/-6 years; 1 female and 6 males) were tested in pure moment loading in flexion-extension, lateral bending, and axial rotation. Thoracolumbar burst fractures were surgically induced at L-1, and testing was repeated sequentially for each of the following fixation techniques: short-segment anterolateral, circumferential, and extended anterolateral. Primary and coupled 3D motions were measured across the instrumented site (T12-L2) and compared across treatment groups.

RESULTS

Circumferential and extended anterolateral fixations were statistically equivalent for primary and off-axis range-of-motions in all loading directions, and short-segment anterolateral fixation offered significantly less rigidity than the other 2 methods.

CONCLUSIONS

The results of this study strongly suggest that extended anterolateral fixation is biomechanically comparable to circumferential fusion in the treatment of unstable thoracolumbar burst fractures with posterior column and posterior ligamentous injury. In cases in which an anterior procedure may be favored for load sharing or canal decompression, extension of the anterior instrumentation and fusion one level above and below the unstable segment can result in near equivalent stability to a 2-stage circumferential procedure.

Adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) affects 1-3% of children in the at-risk population of those aged 10-16 years. The aetiopathogensis of this disorder remains unknown, with misinformation about its natural history. Non-surgical treatments are aimed to reduce the number of operations by preventing curve progression. Although bracing and physiotherapy are common treatments in much of the world, their effectiveness has never been rigorously assessed. Technological advances have much improved the ability of surgeons to safely correct the deformity while maintaining sagittal and coronal balance. However, we do not have long-term results of these changing surgical treatments. Much has yet to be learned about the general health, quality of life, and self-image of both treated and untreated patients with AIS.

Pediatric scoliosis and kyphosis

Pediatric spinal deformity is a common manifestation of multiple disorders. The clinical picture varies depending on the age at presentation, the severity of the curve at the time of diagnosis, and the underlying cause. Knowledge of the natural history of these varied conditions, the dynamics of growth in the developing spine, and normal axial skeletal biomechanics are fundamental in planning an appropriate treatment. Furthermore, in many instances the spinal anomaly is just part of the problem in a globally affected patient. Treatment alternatives must be judged based on their capacity to positively alter the natural course of the disease and provide a long-standing solution into a patient's adulthood.

Anterior and thoracoscopic scoliosis surgery for idiopathic scoliosis

Surgical management of idiopathic scoliosis is based on the natural history of this spinal disorder and on the likelihood of developing a worsening deformity. Anterior surgical treatments continue to evolve and provide advantages over posterior procedures in specific instances. Open and thoracoscopic anterior approaches allow direct access to the anterior stabilizing structures of the spine, enable mobilization of a rigid deformity, and provide a large surface area for arthrodesis. Thoracoscopic procedures provide a more cosmetically appealing alternative to a large midline posterior or anterolateral thoracotomy scar. Although the indications and contraindications for anterior versus posterior surgical intervention (for thoracic and thoracolumbar curve patterns) have been defined to some degree, there remains appropriate flexibility in the decision-making process, allowing the surgeon to make an optimal recommendation for each patient based on surgeon experience and patient needs.

Perioperative Aspects of Endoscopic Anterior Scoliosis Surgery: The Learning Curve for a Consecutive Series of 100 Patients

The reported benefits of endoscopic versus open scoliosis surgery include improved visualization, a muscle sparing approach, reduced pulmonary morbidity, reduced pain, and improved cosmesis. Some aspects of the surgical learning curve for this technically demanding method have been previously reported; however, improvements in other factors with increasing experience have not been quantified. This paper presents a series of 100 consecutive endoscopic anterior scoliosis corrections performed between April 2000 and February 2006. We report changes in the following perioperative factors with increasing experience; operative set-up time, operative time, x-ray irradiation time, number of instrumented levels, blood loss, intercostal catheter drainage, chest drain removal time, days in intensive care, days to mobilize, days in hospital, and early complications. Statistical comparisons were made between the first 20 (1 to 20), middle 20 (41 to 60), and last 20 (81 to 100) cases. Results showed statistically significant improvements and increased consistency in operative time, operative set-up time, x-ray irradiation time, blood loss, hospital stay, and mobilization time with experience. The complication rate was comparable to other recently published endoscopic studies. In the last 20 cases of the series, operative times had reduced to 35 minutes per level, x-ray irradiation times to 15 seconds per level, and blood loss to 38 mL per level. Most perioperative surgical factors therefore improve significantly with increasing experience in endoscopic anterior scoliosis correction.

Anterior lumbar instrumentation improves correction of severe lumbar Lenke C curves in double major idiopathic scoliosis

Fifteen skeletally immature patients with double major adolescent idiopathic scoliosis with large lumbar curves and notable L4 and L5 coronal plane obliquity were retrospectively studied. Seven patients who underwent anterior release and fusion of the lumbar curve with segmental anterior instrumentation and subsequent posterior instrumentation ending at L3 were compared with eight patients treated with anterior release and fusion without anterior instrumentation followed by posterior instrumentation to L3 or L4. At 4.5 years follow-up (range 2.5-7 years), curve correction, coronal balance and fusion rate were not statistically different between the two groups; however, the group with anterior instrumentation had improved coronal plane, near normalangulation in the distal unfused segment compared with the group without anterior instrumentation. In cases involving severe lumbar curvatures in the context of double major scoliosis, when as a first stage anterior release is chosen, the addition of instrumentation appears to restore normal coronal alignment of the distal unfused lumbar segment, and may in certain cases save a level compared with traditional fusions to L4.

Thoracoscopic scoliosis surgery affects pulmonary function less than thoracotomy at 2 years postsurgery

STUDY DESIGN

Prospective evaluation of pulmonary function before and 2 years after surgery following anterior scoliosis instrumentation.

OBJECTIVES

To determine if thoracoscopic anterior scoliosis correction with instrumentation affected pulmonary function less than open thoracotomy approaches at 2 years follow-up.

SUMMARY OF BACKGROUND DATA

The thoracoscopic approach has been shown to have a smaller reduction in pulmonary function tests (PFTs) compared with an open thoracotomy approach following anterior thoracic instrumentation for adolescent idiopathic scoliosis in the immediate postoperative period; however, it is unclear if a difference remains 2 years following the procedure.

METHODS

A total of 107 patients in a multicenter adolescent idiopathic scoliosis database underwent an anterior instrumented fusion for thoracic scoliosis. PFTs assessing forced vital capacity (FVC), forced expiratory volume (FEV1), and total lung capacity (TLC) were obtained prospectively before and 2 years after surgery. The patients were grouped as follows: Group I, thoracoscopic instrumented fusion (n = 36); Group II, open (thoracotomy) instrumented fusion without thoracoplasty (n = 28); and Group III, open instrumented fusion with thoracoplasty (n = 43).

RESULTS

Thoracoscopic instrumentation affected pulmonary function 2 years after surgery minimally, and on an average showed improvements in all parameters except the percent-predicted FVC, which decreased by 1% +/- 11%, and percent predicted FEV, which decreased by 2% +/- 9%. Improvements were noted in absolute FVC, FEV1, TLC, and percent-predicted TLC. This is in contrast to the patients treated with a thoracotomy, who had a greater persistent reduction in PFTs at follow-up. An added thoracoplasty to the thoracotomy approach, however, resulted in even greater residual reduction in PFTs at follow-up, with declines in percent-predicted FVC of 15%, percent-predicted FEV1 of 14%, and percent-predicted TLC of 8%.

CONCLUSIONS

This study shows a clear advantage to the minimally invasive thoracoscopic approach with regards to pulmonary function when compared with the open thoracotomy approaches.

Biomechanical study of anterior spinal instrumentation configurations

The biomechanical impact of the surgical instrumentation configuration for spine surgery is hard to evaluate by the surgeons in pre-operative situation. This study was performed to evaluate different configurations of the anterior instrumentation of the spine, with simulated post-operative conditions, to recommend configurations to the surgeons. Four biomechanical parameters of the anterior instrumentation with simulated post-operative conditions have been studied. They were the screw diameter (5.5-7.5 mm) and its angle (0 degrees - 22.5 degrees), the bone grip of the screw (mono-bi cortical) and the amount of instrumented levels (5-8). Eight configurations were tested using an experimental plan with instrumented synthetic spinal models. A follower load was applied and the models were loaded in flexion, torsion and lateral bending. At 5 Nm, average final stiffness was greater in flexion (0.92 Nm/degrees) than in lateral bending (0.56 Nm/degrees) and than in torsion (0.26 Nm/degrees). The screw angle was the parameter influencing the most the final stiffness and the coupling behaviors. It has a significant effect (p < or = 0.05) on increasing the final stiffness for a 22.5 degrees screw angle in flexion and for a coronal screw angle (0 degrees) in lateral bending. The bi-cortical bone grip of the screw significantly increased the initial stiffness in flexion and lateral bending. Mathematical models representing the behavior of an instrumented spinal model have been used to identify optimal instrumentation configurations. A variation of the angle of the screw from 22.5 degrees to 0 degrees gave a global final stiffness diminution of 13% and a global coupling diminution of 40%. The screw angle was the most important parameter affecting the stiffness and the coupling of the instrumented spine with simulated post-operative conditions. Information about the effect of four different biomechanical parameters will be helpful in preoperative situations to guide surgeons in their clinical choices.

A prospective assessment of SRS-24 scores after endoscopic anterior instrumentation for scoliosis

STUDY DESIGN

Prospective clinical case series.

OBJECTIVE

To evaluate the clinical outcome of anterior endoscopic instrumention for scoliosis using the SRS-24 questionnaire and to examine how these scores change over a 2-year follow-up period.

SUMMARY OF BACKGROUND DATA

Anterior endoscopic instrumentation correction has several advantages compared with open procedures. However, the clinical results of this technique using a validated outcome measure have rarely been reported in the literature.

METHODS

A total of 83 consecutive patients underwent endoscopic anterior instrumentation performed at a single unit. Patients completed the SRS-24 questionnaire before surgery and at 3, 6, 12, and 24 months after surgery. The SRS-24 scores were compared between each of the follow-up intervals.

RESULTS

The pain, general self-image, and function from back condition domains improved after surgery (P < 0.05). Activity level significantly improved between 3 and 6 months, and both function domains improved between 6 and 12 months (P < 0.05). None of the domains increased significantly after 1 year.

CONCLUSIONS

Endoscopic anterior instrumentation for scoliosis significantly improved pain, self-image, and function. The greatest improvement in function occurred between 6 and 12 months after surgery. The SRS-24 scores at 1 year from surgery may provide a good indicator of patient outcome in the long-term.

Prospective radiographic and clinical outcomes of dual-rod instrumented anterior spinal fusion in adolescent idiopathic scoliosis: comparison with single-rod constructs

STUDY DESIGN

Anterior single or dual-rod instrumentation may be performed for the treatment of main thoracic, thoracolumbar, or lumbar adolescent idiopathic scoliosis (AIS) curves.

OBJECTIVE

To compare the results of anterior dual-rod instrumentation in single-major AIS curves with our previous experience using single-rod constructs.

SUMMARY OF BACKGROUND DATA

Several reports have described the use of anterior single-rod instrumentation for the treatment of AIS curves with acceptable correction rates but with pseudarthroses/implant failures of up to 31%.

METHODS

A total of 60 consecutive patients with AIS (12 males and 48 females; average age 15.3 years) with major thoracic (n = 18) or thoracolumbar/lumbar (n = 42) curves were treated with dual-rod instrumented anterior spinal fusion. Follow-up was 2-5 years. Patients were evaluated prospectively with Scoliosis Research Society (SRS) questionnaires.

RESULTS

Major thoracic curves were corrected from a mean of 55 degrees to 27 degrees (51% correction), while major thoracolumbar/lumbar curves were corrected from an average of 51 degrees to 17 degrees at latest follow-up (67% correction). No pseudarthroses were identified. With the use of single-rod constructs, a similar amount of coronal correction was obtained for both thoracic (47%) and thoracolumbar/lumbar curves (70%). However, the pseudarthrosis rate for single-rod constructs was 5.5%. The obvious trend toward a lower pseudarthrosis rate in dual-rod (0/60) versus single-rod (5/90) constructs was not statistically significant (P = 0.07). Follow-up SRS questionnaire data for patients with dual-rod instrumentation showed 95% satisfaction, and 93% would choose the same treatment with similar results in the single-rod instrumentation study, 88% patient satisfaction, and 89% choosing the same treatment. Overall SRS scores improved after treatment (P < 0.01). SRS domain scores improved at a significant level for pain (P = 0.05), self-image (P < 0.01), and function (P = 0.01).

CONCLUSION

In this largest, to our knowledge, single-center report of dual-rod constructs for patients with AIS, a similar amount of radiographic deformity correction was obtained when compared to single-rod implants. However, the absence of any pseudarthroses in the 60 patients with dual-rod is a distinct advantage.

Anterior instrumentation for thoracolumbar adolescent idiopathic scoliosis: do structural interbody grafts preserve sagittal alignment better than morselized rib autografts?

STUDY DESIGN

This is a retrospective, sequential cohort study of 34 patients treated by anterior instrumented fusion with single solid rod, single screw constructs with at least 2-year follow-up. Sixteen of the patients received structural grafts as interbody spacers in disc levels below T12, while the other 18 patients received only morselized rib autograft.

OBJECTIVE

To determine if structural interbody grafts preserve sagittal alignment better than morselized rib autograft.

SUMMARY OF BACKGROUND DATA

Some studies have shown that structural grafts are more effective in preserving sagittal alignment, while others have found them to be no more effective than morselized rib graft.

METHODS

Anterior-posterior radiographs were measured for primary, secondary, and fractional Cobb curves, and C7-sacrum plumb lines. Lateral radiographs were measured for: T5-HIV (highest instrumented vertebrae), instrumented levels, LIV (lowest instrumented vertebrae)-S1, T12-LIV, and T12-S1 angles, C7-sacrum plumb lines, and LID-A (lowest instrumented disc-angle).

RESULTS

The increase in kyphosis from preoperative to follow-up radiographs of the angle between T12-LIV was significantly more for the patients with morselized rib graft compared with those with structural grafts, 9 degrees and 1 degree, respectively (P < 0.05).

CONCLUSIONS

The structural grafts placed in disc spaces below T12 were able to maintain sagittal alignment over this region, while the spines that received only morselized rib graft collapsed into kyphosis.

Biomechanical comparison of the screw-bone interface: optimization of 1 and 2 screw constructs by varying screw diameter

STUDY DESIGN

In vitro biomechanical investigation of 1 and 2-screw anterior scoliosis constructs with varying screw diameters.

OBJECTIVE

To determine a possible optimal configuration of screw number and diameter at varying levels within the thoracic spine for anterior vertebral body fixation.

SUMMARY OF BACKGROUND DATA

Single-rod systems are typical in anterior thoracic and thoracolumbar correction of adolescent idiopathic scoliosis; although dual rod systems may offer more flexural stability. Loss of fixation remains problematic, particularly in the proximal thoracic vertebrae, and it remains unclear how screw diameter or the number of screws within the vertebrae affect fixation.

METHODS

Individual vertebral levels from 10 cadaveric thoracic spines were randomly assigned to either 1 or 2 screws of 5, 6, or 7-mm diameter. Bone-screw interface failures were created in coronal plane cantilever plow, and failure loads were compared across vertebral levels for each instrumentation method.

RESULTS

Two-screw constructs had significantly higher failure loads than single-screw constructs, while increasing screw diameter also produced significant changes in fixation strength. Two-screws had improved performance in the mid and lower thoracic spine, while a single screw was more stable in the upper thoracic spine.

CONCLUSIONS

Failure modes for 1-screw constructs almost entirely (89%) showed gradual plowing through the bone, whereas acute fracture through the vertebral body or pedicles were common forms of failure (85%) for 2-screw constructs.

Postoperative analgesia after anterior correction of thoracic scoliosis: a prospective randomized study comparing continuous double epidural catheter technique with intravenous morphine

STUDY DESIGN

Prospective randomized comparative study of two techniques for postoperative analgesia.

OBJECTIVE

Assess the efficacy of two epidural catheters compared with intravenous morphine after anterior correction of thoracic scoliosis.

SUMMARY OF BACKGROUND DATA

Spine surgery with anterior thoracotomy can cause severe postoperative pain. Continuous epidural analgesia through two epidural catheters was shown to be effective after posterior scoliosis correction. The efficacy of this technique has still not been demonstrated in this surgical context.

METHODS

Thirty adolescent patients with thoracic idiopathic scoliosis scheduled for anterior correction were prospectively randomized into morphine (M) or epidural (E) group. In the E group, two epidural catheters were placed transforaminally after scoliosis correction. The immediate postoperative analgesia was performed with remifentanil in all patients until the first postoperative morning (T0 = begin of study), when either continuous intravenous morphine (M group) or continuous epidural ropivacaine 0.3% (E group) was initiated. Pain at rest and in motion, morphine consumption, sensory level, motor blockade, nausea/vomiting, pruritus, bowel function, and patient satisfaction were assessed.

RESULTS

In the E group, there was significantly less pain at rest and in motion, less rescue morphine consumption, improved bowel activity, and higher patient satisfaction. The incidence of side effects was significantly higher in M group.

CONCLUSIONS

Two epidural catheters provide better postoperative analgesia with fewer side effects and higher patient satisfaction after anterior instrumentation of thoracic scoliosis.