Comparison of radiographic outcomes for the treatment of scoliotic curves greater than 100 degrees: wires versus hooks versus screws

Instrumentation of hypoplastic pedicles with patient-specific guides

PURPOSE

Hypoplastic pedicles of the thoracolumbar spine (<5 mm diameter) are often found in syndromic deformities of the spine and pose a challenge in pedicle screw instrumentation. 3D-printed patient-specific guides might help overcome anatomical difficulties when instrumenting pedicles with screws, thereby reducing the necessity for less effective fixation methods such as hooks or sublaminar wires. In this study, the surgical feasibility and clinical outcome of patients with hypoplastic pedicles following pedicle screw instrumentation with 3D-printed patient-specific guides were assessed.

METHODS

Hypoplastic pedicles were identified on preoperative computed tomography (CT) scans in six patients undergoing posterior spinal fusion surgery between 2017 and 2020. Based on these preoperative CT scans, patient-specific guides were produced to help with screw instrumentation of these thin pedicles. Postoperatively, pedicle-screw-related complications or revisions were analyzed.

RESULTS

93/105 (88.6%) pedicle screws placed with patient-specific guides were instrumented. 62/93 (66.7%) of these instrumented pedicles were defined as hypoplastic with a mean width of 3.07 mm (SD  ±0.98 mm, 95% CI [2.82-3.32]). Overall, 6 complications in the 62 hypoplastic pedicles (9.7%) were observed and included intraoperatively managed 4 cerebrospinal fluid leaks, 1 pneumothorax and 1 delayed revision due to 2 lumbar screws (2/62, 3.3%) impinging the L3 nerve root causing a painful radiculopathy. The mean follow-up time was 26.7 (SD  ±11.7) months. Complications were only noted when the pedicle-width-to-screw-diameter ratio measured less than 0.62.

CONCLUSION

Patient-specific 3D-printed guides can aid in challenging instrumentation of hypoplastic pedicles in the thoracolumbar spine, especially if the pedicle-width-to-screw-diameter ratio is greater than 0.62.

A Comparative Study of Surgical Correction of Idiopathic Scoliosis With Spinal Transpedicular Metal Structures in Children

A comparative study of surgical correction of idiopathic thoracic scoliosis using transpedicular spinal systems in children was performed. The study showed that using the transpedicular supporting elements along the entire length of the deformation (concave and convex sides) using the VCM (vertebral column manipulation) system, the correction was significantly better (p ≤ 0.05) than for the patients for whom the screws were not installed over two or more vertebrae from the concave side of the curvature, regardless of the magnitude of the spinal deformity. The kyphosis and lordosis were completely restored to their physiological values in all groups of patients.

Hybrid versus total sublaminar wires in patients with spinal muscular atrophy undergoing scoliosis surgery

Background

Early versions of spinal muscular atrophy (SMA) scoliosis correction surgery often involved sublaminar devices. Recently, the utilization of pedicle screws has gained much popularity. Pedicle screws are generally believed to provide additional deformity correction, but pedicle size and rotational deformity limit their application in the thoracic spine, resulting in a hybrid construct involving pedicle screws and sublaminar wire. Studies of the efficacy of hybrid instrumentation in SMA scoliosis are often limited by the scarcity of the disease itself. In this study, we aimed to compare the surgical outcomes between hybrid constructs involving pedicle screws and sublaminar wire and sublaminar wire alone in patients with SMA scoliosis.

Methods

We retrospectively reviewed the clinical records and radiographic assessments of patients with SMA scoliosis who underwent corrective surgery between 1993 and 2017. The radiographic assessments included deformity correction and progressive changes in the major curve angle, pelvic tilt (PT) and coronal balance (CB). The correction of deformities was observed postoperatively and at the patient’s 2-year follow-up to test the efficacy of each type of construct.

Results

Thirty-three patients were included in this study. There were 14 and 19 patients in the wiring and hybrid construct groups, respectively. The hybrid construct group demonstrated a higher major curve angle correction (50.5° ± 11.2° vs. 36.4° ± 8.4°, p < 0.001), a higher apical vertebral rotation correction (10.6° ± 3.9° vs. 4.8° ± 2.6°, p < 0.001), and a reduced progression of the major curve angle at the 2-year follow-up (5.1° ± 2.9° vs. 8.7° ± 4.8°, p < 0.001). A moderate correlation was observed between the magnitude of correction of the apical vertebral rotation angle and the major curve (r = 0.528, p = 0.002).

Conclusion

This study demonstrated that hybrid instrumentation can provide a greater magnitude of correction in major curve and apical rotation as well as less major curve progression than sublaminar wire instrumentation alone in patients with SMA scoliosis. Level of evidence III

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04737-0.

Is the Risk of Aorta Injury or Impingement Higher During Correction Surgery in Patients with Severe and Rigid Scoliosis?

OBJECTIVE

To evaluate the position of the aorta relative to the spine and the risk of aortic injury during correction surgery in patients with idiopathic severe and rigid scoliosis (main curve Cobb angle >90° and flexibility <30%).

METHODS

Twenty-seven patients with severe right thoracic/thoracolumbar scoliosis were recruited. The entry point-aorta distance (EAD), the left pedicle-aorta angle (α), the left aorta angle (β), and the vertebral rotation angle (γ) were measured from 4 vertebrae above (A4) to 4 below (B4) the apical vertebra (Apex) to quantify the spatial relationship between aorta and spine. We simulated the pedicle screw misplacement with variable direction error, length, and diameter to analyze the potential risk of aortic injury.

RESULTS

The aorta shifted laterally and posteriorly as it descended from A4 and moved back medially and anteriorly from Apex. The potential risk of aortic injury increased with the augment of direction error and/or length of the screw, but the tendency was not significant with the augment of diameter. The risk peaked at A4, A3, and B2, when the screw length was 40 mm and diameter was 5.0 mm, and the direction error was 30°, whereas the risk was lowest at the apical level 14.3% (0%-40.7%) in any scenarios.

CONCLUSIONS

In patients with severe and rigid scoliosis, the aorta shifted more laterally and posteriorly, and the injury risk was lower at the apical level, compared with moderate scoliosis. Most potential risks can be minimized by careful preoperative planning and the assistance of intraoperative navigation or robotics.

Periapical Wires Result in Less Curve Correction Than Pedicle Screw Constructs in Idiopathic Scoliosis

STUDY DESIGN

Retrospective study.

PURPOSE

The objective of this study was to compare percent correction between apical and periapical pedicle screw (PS) and sublaminar wire constructs for Cobb correction and coronal balance correction.

OVERVIEW OF LITERATURE

The current gold standard for deformity correction in adolescent idiopathic scoliosis (AIS) are PS constructs. Sublaminar wires provide an alternative means of fixation when PS fixation cannot be safely performed. Two previous studies have compared percent curve correction between sublaminar wires and PSs, with conflicting conclusions.

METHODS

The study was a retrospective review of Lenke type 1 curves with minimum follow-up of at least 1 year. Cases were divided into two groups: constructs using apical/periapical sublaminar wires (SL group) versus PS only constructs (PS group). Percent Cobb correction and coronal balance were compared between the two groups at 1 year. A multivariable regression model was used to determine the impact of apical/periapical wires on percent Cobb correction and coronal balance at 1 year when accounting for additional variables.

RESULTS

The cohort included 71 patients who were predominantly female (80.2%), with average age of 14.2 years. Only 21 (29.5%) of constructs utilized apical/periapical sublaminar wires. There was a significant difference in percent Cobb correction at 1 year for the PS and SL groups (70.26% vs. 60.09%, p=0.05). No difference was observed in overall coronal balance. A multivariable model revealed that apical/periapical wires were negatively associated with percent Cobb correction at 1 year (coefficient=-8.49, p=0.023), while total implant density of the construct was positively associated with correction (coefficient=24.2, p<0.001).

CONCLUSIONS

Use of PSs in the apical and periapical zones resulted in improved percent Cobb correction at 1 year in patients with AIS Lenke type 1 curves. Sublaminar wires remain a useful surgical option and result in equivalent coronal balance compared to PSs.

What Factors Are Associated With Kyphosis Restoration in Lordotic Adolescent Idiopathic Scoliosis Patients?

STUDY DESIGN

Review of a prospective adolescent idiopathic scoliosis (AIS) multicenter registry.

OBJECTIVE

To evaluate predictors of surgical thoracic kyphosis restoration in AIS patients with lordotic preoperative thoracic sagittal profiles.

SUMMARY OF BACKGROUND DATA

Prior work on kyphosis-producing techniques has yielded mixed findings and has focused on the sagittal plane in 2D.

METHODS

A validated formula to predict 3D T5-T12 sagittal alignment using standard 2D measures was applied in a cohort of 1614 Lenke 1-4 patients treated with posterior instrumentation using 5.5-mm-diameter rods. Patients with 3D kyphosis 1 standard deviation (12.2°) below the mean (5.3°) were identified as the study cohort. Predictors of 3D T5-T12 kyphosis at two years were evaluated using univariate analysis followed by Classification and Regression Tree (CART).

RESULTS

There were 134 patients identified. All had preoperative 3D T5-T12 kyphosis of <-7°. The average 3D kyphosis was -13° ± 5° preoperatively and 20° ± 7° at two years (p < .001). The thoracic coronal curve improved from 62° ± 12° to 21° ± 8° at two years (p < .001). Of 15 variables analyzed, multivariate CART analysis identified only surgeon as a predictor of 2-year kyphosis. Two surgeon groups were identified by CART which included those who restored more kyphosis versus those who restored less. Subsequent analysis demonstrated significant differences between groups in the rate of Ponte osteotomies used (p < .023), stainless steel versus cobalt chromium rods (p < .001), and segmental screw fixation (p < .001).

CONCLUSION

Kyphosis restoration in patients with preoperative lordosis in the thoracic sagittal plane is possible. In this analysis, there was not one single technique identified as being solely responsible for the ability to restore kyphosis. The most predictive factor identified was the surgeon performing the correction, which is likely a reflection of focus on deformity correction in three planes, as well as a combination of methods used to restore kyphosis.

LEVEL OF EVIDENCE

Level III, therapeutic.

Rod fracture after long construct fusion in adult spinal deformity surgery: A retrospective case-control study

BACKGROUND

Very few studies have focused on the complication of rod fracture after posterior long construct fusion in adults with spinal deformity. Therefore, this retrospective study aimed to investigate the incidence and risk factors of this complication.

METHODS

The study reviewed 213 adult patients with spinal deformity treated by long construct fusion between January 2009 and January 2017. Ten patients (4.6%) with rod fracture were included in the case study group. For each case of rod fracture, we selected two age-matched and gender-matched controls. Independent two-sample t test and Chi-square test were used to compare the differences between variables. Binary logistic regression analysis was performed to identify independent risk factors of rod fracture.

RESULTS

Statistically significant differences were observed between the groups, in terms of additional bone grafts volume (P = 0.015), osteotomy (P = 0.017), skipped screw in sagittal apex region (P = 0.012), TK change (P = 0.023), and preoperative TLK (P = 0.036). However, there were no differences in terms of age (P = 0.933), follow-up time (P = 0.513), gender distribution (P = 0.650), fusion segments (P = 0.085), the number of screws (P = 0.131), density of screws (P = 0.088), preoperative MC (P = 0.120), postoperative MC (P = 0.430), MC change (P = 0.126), preoperative TK (P = 0.590), postoperative TLK (P = 0.074), TLK change (P = 0.064), preoperative LL (P = 0.084), postoperative LL (P = 0.065), and LL change (P = 0.914). Binary logistic regression analysis revealed that osteotomy (P = 0.023) and skipped screw strategy in sagittal apex region (P = 0.046) were the primary factors included in the equation [Odds Ratio (OR) = 11.669 and 7.659, respectively].

CONCLUSION

In our study, the prevalence of rod fracture in adult patients with spinal deformity after long construct fusion was 4.6%; osteotomy was the main risk factor of rod fracture these patients. The skipped screws in sagittal apex region could increase the risk of rod fracture because the stress on the rods failed to be distributed to different segments.

Screw Placement at the Apex Alters Surgical Outcomes of Moderate Lenke 1 Adolescent Idiopathic Scoliosis

STUDY DESIGN

Retrospective study.

OBJECTIVE OF THE STUDY

The objective was to investigate the effect of apical pedicle screw placement on surgical outcomes of Lenke 1 adolescent idiopathic scoliosis (AIS).

SUMMARY OF THE BACKGROUND DATA

Pedicle screw instrumentation achieves satisfactory correction of scoliosis in thoracic AIS patients, but the effect of apical screw placement is unclear.

MATERIALS AND METHODS

Lenke 1 AIS patients with all pedicle screw instrumentation between January 2009 and January 2011 were reviewed. According to the presence of apical vertebra instrumentation, 38 patients (group A) were identified without apical screw placement. 25 patients (group B) instrumented with both concave, and convex apical screws and 50 patients (group C) with either concave or convex apical pedicle screw instrumentation were also enrolled according to matched age and Cobb angles. Cobb angle correction, apical vertebral derotation, misplacement of apical screws, functional outcomes, and patient satisfaction were evaluated.

RESULTS

Demographic parameters and preoperative Cobb angle, curve flexibility, and apex rotation were similar among the 3 groups (P>0.05). Postoperatively, there was no significant difference regarding the number of fused vertebrae, Cobb angle correction rate, or loss of correction. However, the degree of apical vertebral derotation was significantly lower in group A (17.8%) than in groups B (49.1%) and C (34.3%) (P<0.001). In group B, 6 screws inserted on the concavity and 5 on the convexity of the apex were identified as malpositioned; whereas in group C, 3 on the concavity and 2 on the convexity were malpositioned screws. Self-image and satisfaction were highest for patients in group B.

CONCLUSIONS

For patients with moderate Lenke 1 AIS (Cobb angle, 50-70 degrees), the insertion of apical pedicle screws did not significantly improve curve correction, but it had a marked positive effect on the derotation of apical vertebrae, subsidence of the rib hump, and patient satisfaction.

Severe Rigid Scoliosis: Review of Management Strategies and Role of Spinal Osteotomies

Severe rigid curves pose a considerable challenge to the treating spine surgeon. In our practice, approximately 30%–40% of patients with scoliosis present late with severe rigid scoliosis (>90° and <30% correction on bending films). Controversy still exists with regard to the ideal surgical strategy for correcting these rigid curves. Rigid scoliosis often presents in the form of either sharp angular or rounded deformities. Rounded deformities can be effectively managed with an anterior release to loosen the apex and posterior instrumentation (with osteotomies, if required). In contrast, severe rigid scoliosis, which is a sharp angular deformity, is not very amenable to anterior release and is best managed by posterior-only vertebral column resection and posterior instrumentation.

Staged Anterior Release and Posterior Instrumentation in Correction of Severe Rigid Scoliosis (Cobb Angle >100 Degrees)

PURPOSE

Severe rigid curves present a big challenge to the treating spine surgeon. We evaluated the outcome of staged anterior release and posterior instrumentation for rigid scoliosis.

METHODS

Twenty-one patients with an average age of 14.4 years (range 11-17) having a rounded severe rigid scoliosis (Cobb angle >100 degrees) underwent surgical correction. Six patients had congenital scoliosis, 13 idiopathic scoliosis, and 2 syndromic. All patients underwent anterior release in Stage I with one or more Ponte osteotomies and in Stage II with all pedicle screw instrumentation, and 13 of the patients underwent an asymmetric pedicle subtraction osteotomy at the apex. Patients were assessed for deformity correction, operative time, blood loss, and any complications.

RESULTS

The preoperative Cobb angle of 116.6 degrees (range 101-124 degrees) improved to 74.0 degrees (range 54-86 degrees) after anterior release: 29.4% correction and the final postoperation Cobb angle after posterior instrumentation was 26.5 degrees (range 22-32 degrees), with final 76% correction. The average blood loss in anterior release was 585.95 mL (range 400-980 mL; % estimated blood volume = 19.5%), whereas the mean operative time was 223 minutes (165-315 minutes). One patient had prolonged chest drain and two, basal atelectasis following anterior release. The mean operative time for the posterior procedure was 340 minutes (range 280-420 minutes) and average blood loss was 2,066 mL (range 1,200-3,200 mL). The mean apical axial rotation of 56 degrees (range 26-79 degrees) improved to 28 degrees (range 9-42 degrees) (p < .05). There was loss of motor evoked potential signal in one and hook pullout, superficial infection, and local skin necrosis one case each.

CONCLUSION

The staged approach to the management of severe, rigid scoliosis helps get an excellent correction. Anterior release loosens up the rigid apex and provides with nearly 30% correction so that the extent of the osteotomies in the second stage from the back is substantially reduced, allowing for a final good correction.

Could CCI or FBCI Fully Eliminate the Impact of Curve Flexibility When Evaluating the Surgery Outcome for Thoracic Curve Idiopathic Scoliosis Patient? A Retrospective Study

Purpose

To clarify if CCI or FBCI could fully eliminate the influence of curve flexibility on the coronal correction rate.

Methods

We reviewed medical record of all thoracic curve AIS cases undergoing posterior spinal fusion with all pedicle screw systems from June 2011 to July 2013. Radiographical data was collected and calculated. Student t test, Pearson correlation analysis and linear regression analysis were used to analyze the data.

Results

60 were included in this study. The mean age was 14.7y (10-18y) with 10 males (17%) and 50 females (83%). The average Risser sign was 2.7. The mean thoracic Cobb angle before operation was 51.9°. The mean bending Cobb angle was 27.6° and the mean fulcrum bending Cobb angle was 17.4°. The mean Cobb angle at 2 week after surgery was 16.3°. The Pearson correlation coefficient r between CCI and BFR was -0.856(P<0.001), and between FBCI and FFR was -0.728 (P<0.001). A modified FBCI (M-FBCI) = (CR-0.513)/BFR or a modified CCI (M-CCI) = (CR-0.279)/FFR was generated by curve estimation has no significant correlation with FFR (r=-0.08, p=0.950) or with BFR (r=0.123, p=0.349).

Conclusions

Fulcrum-bending radiographs may better predict the outcome of AIS coronal correction than bending radiographs in thoracic curveAIS patients. Neither CCI nor FBCI can fully eliminate the impact of curve flexibility on the outcome of correction. A modified CCI or FBCI can better evaluating the corrective effects of different surgical techniques or instruments.

Morbidity and radiographic outcomes of severe scoliosis of 90° or more: a comparison of hybrid with total pedicle screw instrumentation

OBJECTIVES

Untreated severe scoliosis is associated with increased mortality and remains a significant surgical challenge. Few studies have reported mortality after the surgical treatment of severe scoliosis beyond a 2-year follow-up. The objectives of this study were to evaluate mortality beyond standard 2-year follow-up and compare radiographic outcomes using hybrid or pedicle screw instrumentation for severe scoliosis.

METHODS

We evaluated 32 consecutive patients [11 males, mean age at surgery 15.3 (range 10.7-20.7) years] operated for a scoliosis of 90° or more using either hybrid (n = 15) or pedicle screw (n = 17) instrumentation. The follow-up time averaged 2.9 (2.0-6.6) years for radiographic and quality of life measurements and 5.5 years (2.0-9.0) years for mortality data. Of these patients, one had adolescent idiopathic scoliosis, three secondary scoliosis, and 28 neuromuscular scoliosis. Twelve patients in the hybrid and two patients in the pedicle screw groups underwent anteroposterior surgery (p < 0.001), and three patients in both groups had an apical vertebral column resection.

RESULTS

One (3.1 %) patient died during follow-up for severe pneumonia. Preoperatively, the mean magnitude of the major curve was 109° (90°-127°) in the hybrid and 100° (90°-116°) in the pedicle screw groups (p = 0.015), and was corrected to 45° (19°-69°) in the hybrid and 27° (18°-40°) in the pedicle screw groups at the 2-year follow-up (p < 0.001), with a mean correction of the major curve of 59 % (37-81 %) in the hybrid versus 73 % (60-81 %) in the pedicle screw groups, respectively (p = 0.0023). There were six postoperative complications, including one transient spinal cord deficit necessitating reoperation in the hybrid group as compared with five complications in the pedicle screw group (p = 0.53).

CONCLUSIONS

The mid-term mortality rate after the surgical treatment of severe scoliosis was low. Severe scoliosis can be treated safely with significantly better correction of the spinal deformity using pedicle screws than hybrid instrumentation.

Neuromonitoring with pulse-train stimulation for implantation of thoracic pedicle screws: a blinded and randomized clinical study. Part 2. The role of feedback

Object

The authors have reported in Part 1 of this study on a novel neuromonitoring test for the prevention of medial malpositioning of thoracic pedicle screws. In the present paper they examine the impact of providing the results of the test as intraoperative feedback to the surgical team.

Methods

This is the second part of a 2-part report of a prospective, blinded and randomized neuromonitoring study designed to lower the incidence of medially malpositioned thoracic pedicle screws. Details of the neuromonitoring technique and data supporting the alarm criteria used are contained in the companion article (Part 1). For the majority of pedicle screw placements, intraoperative test results were withheld from the study team (that is, the team members were blinded to the test results). However, for a limited number of pedicle sites the authors provided one of 2 forms of testing feedback to the surgical team: 1) “break the blind” feedback, if testing suggested that screw placement would result in direct contact between screw and the dura mater; and 2) “planned” feedback, beginning during the later stages of the study and provided for 50% of pedicle sites. Feedback gave the surgeon the opportunity to adjust the trajectory that the screw would ultimately take within the pedicle. The final screw position relative to the pedicle's medial wall for all sites in which feedback was withheld from the surgical team was compared with the screw position for those sites in which either form of feedback (“break the blind” or “planned”) was provided to and acted upon by the surgical team.

Results

Of the 820 pedicle tracks tested among the 71 surgical cases included in this study, a total of 684 were operated upon without any form of feedback. Planned feedback was provided for an additional 107 pedicle tracks, of which 15 triggered an intraoperative alarm (evoked electromyogram response in leg muscles to stimulus intensity ≤ 10 mA) leading to a warning to the surgical team of a medially biased pedicle track. Finally, the blind was broken 29 times, in each case when testing revealed a particularly low threshold (≤ 4 mA) for evoked responses in leg muscles when stimulating along the pedicle track with the ball-tipped probe. As detailed in the companion paper to this one, there were 32 screws with threads lying at least 2 mm medial to the pedicle wall. In all 32 instances (100%), either these screws were in the “no feedback” category (n = 29) or they were in a feedback category but the surgeon elected to not revise the pedicle-track trajectory. Two patients returned to the operating room for revision of screw placements because the screws were encroaching upon the central canal; the pedicle tracks for these screws had been in the “no feedback” category.

Conclusions

This is the first blinded and randomized study to prove that implementing a novel neuromonitoring strategy during placement of thoracic pedicle screws can significantly reduce the incidence of clinically relevant thoracic pedicle screw medial malpositioning.

Neuromonitoring with pulse-train stimulation for implantation of thoracic pedicle screws: a blinded and randomized clinical study. Part 1. Methods and alarm criteria

Object

Reports of the accuracy of existing neuromonitoring methods for detecting or preventing medial malpositioning of thoracic pedicle screws have varied widely in their claimed effectiveness. The object of this study was to develop, test, and validate a novel neuromonitoring method for preventing medial malpositioning of pedicle screws in the thoracic spine during surgery.

Methods

This is a prospective, blinded and randomized study using a novel combination of input (4-pulse stimulus trains delivered within the pedicle track) and output (evoked electromyography from leg muscles) to detect pedicle track trajectories that—once implanted with a screw—would cause that screw to breach the pedicle's medial wall and encroach upon the spinal canal. For comparison, the authors also used screw stimulation as an input and evoked electromyogram from intercostal and abdominal muscles as output measures. Intraoperative electrophysiological findings were compared with postoperative CT scans by multiple reviewers blinded to patient identity or intraoperative findings.

Results

Data were collected from 71 patients, in whom 802 screws were implanted between the T-1 and L-1 vertebral levels. A total of 32 screws ended up with screw threads encroaching on the spinal canal by at least 2 mm. Pulse-train stimulation within the pedicle track using a ball-tipped probe and electromyography from lower limb muscles correctly predicted all 32 (100%) of these medially malpositioned screws. The combination of pedicle track stimulation and electromyogram response from leg muscles proved to be far more effective in predicting these medially malpositioned screws than was direct screw stimulation and any of the target muscles (intercostal, abdominal, or lower limb muscles) we monitored. Based on receiver operating characteristic analysis, the combination of 10-mA (lower alarm) and 15-mA stimulation intensities proved most effective for detection of pedicle tracks that ultimately gave rise to medially malpositioned screws. Additional results pertaining to the impact of feedback of these test results on surgical decision making are provided in the companion report.

Conclusions

This novel neuromonitoring approach accurately predicts medially malpositioned thoracic screws. The approach could be readily implemented within any surgical program that is already using contemporary neuromonitoring methods that include transcranial stimulation for monitoring motor evoked potentials.

Restoration of thoracic kyphosis by simultaneous translation on two rods for adolescent idiopathic scoliosis

INTRODUCTION

Sagittal and axial corrections of the three-dimensional deformity characteristic of scoliosis remain challenging.

MATERIALS AND METHOD

The author developed a new technique for scoliosis correction consisting of the translation of vertebrae simultaneously towards two rods, which are pre-bent to the correct sagittal profile. Using two rods ensures both reduction and stabilization of the curve. The system includes stable anchorages with polyaxial-threaded extensions that connect to the rods. Deformity reduction is done by tightening nuts simultaneously and progressively on the two rods. Results demonstrate the efficiency of this technique to achieve normal thoracic kyphosis (>20°) in all 99 patients, with a mean gain of 19° of thoracic kyphosis in hypokyphotic cases. Coronal correction was 70-80% with a vertebral rotation gain of 40% where derotation connectors were used.

CONCLUSIONS

In a large consecutive series of patients, this new technique allows to achieve a good 3D correction of the scoliosis.

Rod fracture after long construct fusion for spinal deformity: clinical and radiographic risk factors

BACKGROUND

No reports have been published on detailed risk factors for rod fracture after spinal deformity correction and fusion. The purpose of this study was to analyze clinical and radiographic risk factors of rod fracture after long construct fusion for spinal deformity.

METHODS

The survey subjects were 155 cases who were diagnosed with spinal deformity and underwent correction and fusion surgery with long construct instrumentation (>3 levels, average 10.3 levels) between July 2004 and June 2010. The subjects comprised 32 males and 123 females with a mean age of 19.0 (range 8-78) years. The mean Cobb angle was 61.0 ± 16.1° preoperatively and 25.7 ± 16.9° postoperatively. Univariate analysis and logistic regression analysis were performed.

RESULTS

Rod fracture occurred in 8 of 155 cases (5.2 %). The mean period from surgery to rod fracture was 18.1 months (range 2-37). The level of fracture ranged from the thoracolumbar junction to the lumbosacral vertebrae. Six patients had fracture near the fused lower end and two patients had fracture at the thoracolumbar junction. Univariate analysis revealed that non-ambulatory status, preoperative kyphosis, small-diameter rods, multiple surgery, and use of iliac screws were significant risk factors for rod fracture. Sex, obesity, severity of preoperative scoliosis, and rod material were not significant risk factors. Logistic regression analysis revealed that use of iliac screws (odds ratio: 81.9, 95 % confidence interval: 7.2-935.0, p < 0.001) and small-diameter (<6 mm) rods (odds ratio: 16.3, 95 % confidence interval: 1.7-152.6, p = 0.015) were risk factors for rod fracture.

CONCLUSIONS

The incidence of rod fracture after long construct fusion for spinal deformity was 5.2 %. Iliac screw fixation and small-diameter rods were risk factors for rod fracture.

The safety of spinal pedicle screws in children ages 1 to 12

BACKGROUND CONTEXT

Pedicle screws have shown to be a safe and effective method of spinal fixation, offering superior multiplanar correction compared with hooks or sublaminar wires in selected situations. Though only food and drug administration (FDA) approved in the adolescent population, they are commonly used in an off-label manner in the preadolescent population.

PURPOSE

To determine if the complication rate of the off-label use of pedicle screws for spinal fixation in the preadolescent 0- to 12-year-old population is comparable with the complication rate in the FDA-approved 13- to 18-year-old population.

STUDY DESIGN/SETTING

Retrospective medical record and radiograph review.

PATIENT SAMPLE

A total of 726 pediatric patients who underwent a spinal fusion procedure at a single tertiary institution between January 2003 and December 2008 were reviewed.

OUTCOME MEASURES

Incidence of instrumentation failure, infection, neurological complication, and total complications.

METHODS

The study population was divided into two groups based on age: the younger group included 0- to 12-year olds and the older group included 13- to 18-year olds at the time of surgery. Groups were further subdivided based on diagnosis: "A," neuromuscular scoliosis; "B," idiopathic scoliosis, and "C," other spinal deformities. Rates of neurovascular complications, infections, and instrumentation complications were compared statistically between the younger and the older groups. Only patients with greater than or equal to 1-year follow-up and greater than or equal to 2-year follow-up were included in the calculations for infection and instrumentation complication rates, respectively.

RESULTS

There were 206 patients (33% males, 67% females) in the younger group (0 to 12 years) and 520 (41% males, 59% females) in the older group (13 to 18 years). Overall, younger group had a 13.6% complication rate compared with 16.9% in the older group. Younger subjects showed a 13.4% complication rate because of instrumentation-related complications, 0.5% for neurovascular complications, and an infection rate of 9.2%. The older group showed a 15.4% complication rate because of instrumentation-related complications, 1.92% for neurovascular complications, and an infection rate of 11.0%. Complication rates were statistically insignificant between the two groups. Other complications in the younger group included one patient with aspiration pneumonia, two with ileus, and one with pulmonary and other complications in the older group included one patient with aspiration pneumonia, two with ileus, three with superior mesenteric artery syndrome, and three with wound dehiscence.

CONCLUSIONS

The complication rates in the young pediatric population associated with the off-label use of pedicle screws for spinal fusions are not statistically different from the complication rates associated with the FDA-approved adolescent population.

Neurological outcome and management of pedicle screws misplaced totally within the spinal canal

STUDY DESIGN

This study reports 9 cases referred to our institution after surgical correction of adolescent idiopathic scoliosis and pedicle screws misplaced totally within the spinal canal.

OBJECTIVE

To assess the neurological outcome associated with pedicle screws misplaced totally within the spinal canal.

SUMMARY OF BACKGROUND DATA

The prevalence of neurological complications from misplaced pedicle screws might be under-reported, and optimal management of pedicle screws misplaced totally within the spinal canal remains unclear.

METHODS

Nine cases with pedicle screws misplaced totally within the spinal canal during posterior surgery for adolescent idiopathic scoliosis were reviewed. All cases presented at least 1 medially misplaced pedicle screw, with spinal canal intrusion greater than pedicle screw diameter, that is, completely within the spinal canal. Percentage of spinal canal intrusion was measured from computed tomographic scans.

RESULTS

Spinal canal intrusion varied from 21% to 61%. In 2 patients, misplacement of pedicle screws was recognized intraoperatively and all implants were removed. They both had motor deficits from which 1 patient recovered completely. Two patients had early postoperative postural headache that disappeared after removal of the misplaced screw. Five patients had uneventful early postoperative course. One of these developed a Brown-Sequard syndrome 2 years after surgery and underwent complete implant removal. Another patient developed left thoracic paresthesia 3 years after surgery, and complete implant removal was performed. Two neurologically intact patients had uneventful implant removal after infection. The last patient refused implant removal and remained asymptomatic 5 years after surgery.

CONCLUSION

Improper pedicle screw placement can lead to neurological complications appearing early or late (after 2 yr). Late neurological complications were associated with screw loosening in 2 cases. The authors strongly recommend removal of any pedicle screw misplaced totally within the spinal canal due to the risk of early or late neurological complications, regardless of the severity of spinal canal intrusion.

Posterior extrapleural intervertebral space release combined with wedge osteotomy for the treatment of severe rigid scoliosis

STUDY DESIGN

Retrospective clinical case series.

OBJECTIVE

To report the technique and results of posterior extrapleural intervertebral space release (PEISR) combined with wedge osteotomy (WO) for the treatment of severe rigid scoliosis.

SUMMARY OF BACKGROUND DATA

Conventional surgical correction techniques for severe rigid scoliosis include anterior release combined with posterior instrumentation and fusion and vertebral column resection.

METHODS

Between 2004 and 2009, 18 patients underwent PEISR and WO at a single institution. The indications were scoliosis with coronal Cobb's angle greater than 90° and curve flexibility less than 25%. The median age at surgery was 18.1 years (range, 13-26 yr). Nine patients had a preoperative forced vital capacity that was less than 40% of predicted. All patients had a minimum 2-year radiographical and clinical follow-up (range, 2.0-5.7 yr).

RESULTS

A mean of 4.2 discs were excised per patient (range, 2-6 discs) along with a mean of 1.2 vertebrae removed in the osteotomy. Mean number of vertebrae fused was 13.8 (range, 10-16 vertebrae). Mean operating time was 8.8 hours (range, 6.2-12.6 hr), with a mean blood loss of 3990 mL (range, 2600-6100 mL). The mean preoperative Cobb angle of 108.5° (range, 92°-136°) was corrected to 30° at the most recent follow-up (72.4% correction rate). Preoperative thoracic kyphosis of 52° (range, 5°-115°) was corrected to 26° (range, 17°-52°). The mean preoperative coronal imbalance of 3.5 cm was corrected to 0.6 cm (83.8% correction) and the sagittal imbalance of 2.8 cm was corrected to 0.3 cm (90.3% correction). There were no neurological complications. There were no instances of infection or muscle necrosis. Hemopneumothorax occurred in 2 patients.

CONCLUSION

PEISR, combined with WO, through a single posterior approach is a technically challenging but safe and effective procedure for severe rigid scoliosis. This posterior-only approach allows for dramatic radiographical correction that surpasses that reported for posterior VCR.

The impact of halo-gravity traction on curve rigidity and pulmonary function in the treatment of severe and rigid scoliosis and kyphoscoliosis: a clinical study and narrative review of the literature

INTRODUCTION

The treatment of rigid and severe scoliosis and kyphoscoliosis is a surgical challenge. Presurgical halo-gravity traction (HGT) achieves an increase in curve flexibility, a reduction in neurologic risks through gradual traction on a chronically tethered cord and an improvement in preoperative pulmonary function. However, little is known with respect to the ideal indications for HGT, its appropriate duration, or its efficacy in the treatment of rigid deformities.

MATERIALS AND METHODS

To investigate the use of HGT in severe deformities, we performed a retrospective review of 45 patients who had severe and rigid scoliosis or kyphoscoliosis. The analysis focused on the impact of HGT on curve flexibility, pulmonary function tests (PFTs), complications and surgical outcomes in a single spine centre.

RESULTS

PFTs were used to assess the predicted forced vital capacity (FVC%). The mean age of the sample was 24±14 years. 39 patients had rigid kyphoscoliosis, and 6 had scoliosis. The mean apical rotation was 3.6°±1.4°, according to the Nash and Moe grading system. The curve apices were mainly in the thoracic spine. HGT was used preoperatively in all the patients. The mean preoperative scoliosis was 106.1°±34.5°, and the mean kyphosis was 90.7°±29.7°. The instrumentation used included hybrids and pedicle screw-based constructs. In 18 patients (40%), a posterior concave thoracoplasty was performed. Preoperative PFT data were obtained for all the patients, and 24 patients had ≥3 assessments during the HGT. The difference between the first and the final PFTs during the HGT averaged 7.0±8.2% (p<.001). Concerning the evolution of pulmonary function, 30 patients had complete data sets, with the final PFT performed, on average, 24 months after the index surgery. The mean preoperative FVC% in these patients was 47.2±18%, and the FVC% at follow-up was 44.5±17% (a difference that did not reach statistical significance). The preoperative FVC% was highly predictive of the follow-up FVC% and the response during HGT. The mean flexibility of the scoliosis curve during HGT was only 14.8±11.4%, which was not significantly different from the flexibility measures achieved on bending radiographs or Cotrel traction radiographs. In rigid curves, the Cobb angle difference between the first and final radiographs during HGT was only 8°±9° for scoliosis and 7°±12° for kyphosis. Concerning surgical outcomes, 13 patients (28.9%) experienced minor and 15 (33.3%) experienced major complications. No permanent neurologic deficits or deaths occurred. Additional surgery was indicated in 12 patients (26.7%), including 7 rib-hump resections. At the final evaluation, 69% of the patients had improved coronal balance, and at a mean follow-up of 33±23.3 months, 39 patients (86.7%) were either satisfied or very satisfied with the overall outcome.

CONCLUSION

The improvement of pulmonary function and the restoration of sagittal and coronal balance are the main goals in the treatment of severe and rigid scoliosis and kyphoscoliosis. A review of the literature showed that HGT is a useful tool for selected patients. Preoperative HGT is indicated in severe curves with moderate to severe pulmonary compromise. HGT should not be expected to significantly improve severe curves without a prior anterior and/or posterior release. The data presented in this study can be used in future studies to compare the surgical and pulmonary outcomes of severe and rigid deformities.

Three-staged correction of severe rigid idiopathic scoliosis using limited halo-gravity traction

INTRODUCTION

Despite the advantages of modern instrumentation techniques, the treatment of severe rigid idiopathic scoliosis could be very demanding. Traction can provide better, safer correction and minimize complications related to forceful intra-operative maneuvers; however, several side effects are associated with prolonged periods of traction. The aim of this work is to review the clinical and radiographic results of limited perioperative halo-gravity traction in severe rigid curves analyzing its efficacy, advantages and possible complications and comparing it to classic two staged corrections performed without traction.

METHODS

A retrospective case control study including 47 adolescents with severe rigid idiopathic scoliosis divided into two groups; a consecutive series of 21 patients who had a three-staged correction by an anterior release, 2 weeks of halo-gravity traction then posterior instrumentation (TRN group); compared to an earlier series of 26 consecutive patients treated without traction (SAP group). The average age was 18 years + 1 month and 16 years + 2 months, respectively. The average preoperative dorsal and lumbar curves for (TRN) group were 106.5° and 87°, respectively, and for (SAP) group were 102° and 81°, respectively.

RESULTS

Patients were followed up for an average of 6 years (range 3-8 years). A significantly better correction was achieved in (TRN) group (average 59%) compared to (SAP) group (average 47%). At final follow-up, the loss of correction had an average of 8° for (TRN) group and 11° for (SAP) group. A shorter hospital stay was found in (SAP) group; a shorter operative time was found in (TRN) group and there was no significant difference in blood loss, early or delayed complications.

CONCLUSIONS

Limited halo-gravity traction is an efficient, safe modality in the treatment of severe rigid adolescent scoliosis. The application of gradual traction over a limited period of 2 weeks led to better correction, shorter operative time with no significant complications.

Adult spine deformity

Adult spinal deformity may occur as the result of a number of conditions and patients may present with a heterogeneous group of symptoms. Multiple etiologies may cause spinal deformity; however, symptoms are associated with progressive and asymmetric degeneration of the spinal elements potentially leading to neural element compression. Symptoms and clinical presentation vary and may be related to progressive deformity, axial back pain, and/or neurologic symptoms. Spinal deformity is becoming more common as adults 55-64 years of age are the fastest growing proportion of the U.S. population. As the percentage of elderly in the United States accelerates, more patients are expected to present with painful spinal conditions, potentially requiring spinal surgery. The decision between operative and nonoperative treatment for adult spinal deformity is based on the severity and type of the patient's symptoms as well as the magnitude and risk of potential interventions.

Fixation points within the main thoracic curve: does more instrumentation produce greater curve correction and improved results?

STUDY DESIGN

Prospective consecutive multicenter case series.

OBJECTIVE

To compare fixation type and amount to curve correction controlled for curve flexibility.

SUMMARY OF BACKGROUND DATA

The enhanced spinal purchase from segmental fixation should increase the force implants can exert without failure. This study evaluates whether this translates into correction beyond that expected from preoperative bending radiographs in thoracic curves where maximum correction was feasible (1A, 1B, and nonselective 1C fusions).

METHODS

One hundred seventy-one Lenke type 1 curves (118 1A, 36 1B, 23 1C) with 2-year follow-up were evaluated for the number and type of fixation points within the main curves compared to the correction obtained on preoperative bend films. SRS scores were compared to the amount of correction.

RESULTS

The number of fixation points both within the curve (P = 0.01) and for each vertebral body (P = 0.002) was larger for curves with greater correction compared to the bend films than those with less correction. Overall absolute correction was best for all screw and screw and wire constructs, followed by hook and screw, and least with hooks. However, compared to the bend films, these differences were not significant (P = 0.132). For all groups, the SRS scores significantly improved (P < 0.001), and was slightly more notable for the all screw constructs than other instrumentation patterns (P = 0.023). However, there were no significant difference in this improvement between those correcting more and those correcting less than the bend films (P = 0.578).

CONCLUSION

Absolute curve correction improved most with all pedicle screw and screw and wire constructs, but, when compared to bending films, the number of fixation points is more important than fixation type for curve correction. Although SRS scores improved the most in those with all screw constructs, the significance of this improvement is uncertain, and the SRS scores did not relate to whether curve correction was more or less than the bend films.

Surgical treatment of neurological scoliosis using hybrid construct (lumbar transpedicular screws plus thoracic sublaminar acrylic loops)

In the nineties, most spinal surgeons supported the validity of segmental spine instrumentation, but this procedure has progressively been abandoned because difficult and with a high risk of neurological complications, in favor of the Cotrel-Dobousset (CD). The CD instrumentation is based on segmentation of curves, thus improving the angular correction and actuates sagittal profile. Sublaminar acrylic loops (Universal Clamp) shows the same resistance to stress as steel or titanium alloy sublaminar wires. The simple procedure and the tensioning of the strips allows re-tensioning and progressive correction. The increased contact area, improves corrective forces, thus reducing the risk of laminar fractures. The aim of this study was to verify the validity of this spinal fixation implant in the surgical treatment of a consecutive series of patients affected by neurologic scoliosis. The authors treated surgically 84 patients affected by neurologic scoliosis with an average age of 14 years (range 10-17). Universal Clamps associated with Socore TM spinal assembly, transpedicular lumbar screws and thoracic hooks at the upper end of the curve were used. The etiology of disease was cerebral palsy in 81 cases, Friedreich ataxia in two cases and Aicardi syndrome in one case. The average preoperative angular value was 73° ± 16°. It was implanted a mean of seven Clamps for each procedure (range 5-9). The average percentage of correction was 72%. Mean operative time was 240 ± 30 min with mean blood loss of 1200 ± 400 ml. No intra-operative complications occurred. Mean follow-up was 36 months. At one-year follow-up the mean loss of correction was 7° ± 2° with no re-intervention required. This is the first report on treatment of neurological scoliosis with this hybrid construct (lumbar screws, thoracic acrylic clamps, thoracic hooks at the upper end of the curve). In this group of patients the Universal Clamps technique appeared safe and effective and its mechanical performance is comparable to all-level screws construct. Furthermore, the kyphotic component can be better managed in case of thoracic lordosis. The most important aspect of this technique is a short operative time and low vascular and neurologic risks combined with a satisfying stability in the short-postoperative period. Nevertheless, it is important to value results on a long-term follow-up to analyze correction loss, pseudoarthrosis, and mechanical failure of the strips.

Efficacy of perioperative halo-gravity traction for treatment of severe scoliosis (≥100°)

BACKGROUND

There have been no standardized surgical options for severe scoliotic curvatures ≥100°. Halo-gravity traction is a viable option for surgical treatment of severe scoliosis. The aim of this study was to evaluate the efficacy and safety of perioperative halo-gravity traction for scoliosis curves ≥100° with respect to radiographic outcomes and clinical complications.

METHODS

A total of 21 scoliosis patients with ≥100° curves (average 118.7°; range 100°-158°) with a minimum 2-year follow-up (average 41.8 months; range 24.0-97.0 months) who underwent spinal instrumented fusion using perioperative halo-gravity traction were analyzed. Diagnoses were neuromuscular scoliosis (n = 10), idiopathic (n = 9), and congenital (n = 2). In all, 15 patients were treated by the anterior release procedure followed by final posterior fusion and 6 patients by posterior fusion alone. Six patients had only preoperative traction preceding posterior fusion alone, 6 patients only staged traction between anterior release and final posterior fusion, and 9 patients had both preoperative traction preceding anterior release and staged traction preceding final posterior fusion. The average overall traction period in all patients was 67 days (range 10-78 days).

RESULTS

Radiographic outcomes demonstrated 51.3% correction of the major Cobb angle, 40 mm correction of apical vertebral translation, 76 mm increase of T1-S1 length, and 20.7% increase of space available for lungs at the ultimate follow-up (all comparisons P < 0.05). Preoperative traction demonstrated 27.5% correction of the major curve Cobb angle, 51.5 mm increase of T1-S1 length, 14.9% increase of space available for the lungs (all comparisons P < 0.05). Staged traction after anterior release demonstrated 37.2% correction of the major curve Cobb angle, 26.1 mm correction of apical vertebral translation, 56.5 mm increase of T1-S1 length, 14.2% increase of space available for the lungs (all comparisons P < 0.05). There were only two patients with a pin-site problem, and one required débridement. There were no neurological deficits or clinical complications.

CONCLUSIONS

Scoliosis patients with ≥100° curves can be managed successfully by corrective fusion surgery concomitant with perioperative halo-gravity traction without significant complications.

Management of spinal deformity in cerebral palsy

An understanding of the three-dimensional components of spinal deformity in children with cerebral palsy is necessary to recommend treatments that will positively affect these patients' quality of life. Management of these deformities can be challenging and orthopedic surgeons should be familiar with the different treatments available for this patient population. This article discusses the incidence, causes, natural history, and treatment of patients with scoliosis.

Comparação do desfecho radiográfico das escolioses idiopáticas do adolescente tratadas com instrumentação híbrida, parafusos pediculares ou ganchos

OBJETIVOS: comparar os resultados radiográficos dos pacientes portadores de escoliose idiopática do adolescente (EIA) tratados cirurgicamente, com instrumentação com ganchos, híbrida ou parafusos pediculares, com seguimento mínimo de um ano. MÉTODOS: avaliação radiográfica retrospectiva dos pacientes portadores de escoliose idiopática do adolescente tratados com diferentes instrumentações, nos períodos pré-operatório, pós-operatório imediato e pós-operatório de um ano utilizando o método de medição de Cobb. RESULTADOS: não houve diferença estatística no comportamento das curvas durante o primeiro ano de seguimento nas curvas torácica, lombar ou na cifose. Quando analisadas de forma quantitativa, não se encontrou diferença estatística nas curvas torácica (p=0,052) e lombar (p=0,332) no período pré-operatório entre os três grupos. Os três instrumentais apresentaram comportamento semelhante, não havendo diferença quantitativa na correção das curvas torácica (p=0,052) e lombar (p=0,267) nos períodos pós-operatório imediato e após um ano de seguimento. CONCLUSÕES: as três estratégias de instrumentação rendem resultados radiográficos similares em pacientes portadores de EIA flexíveis.

Preservation of thoracic kyphosis is critical to maintain lumbar lordosis in the surgical treatment of adolescent idiopathic scoliosis

STUDY DESIGN

Retrospective analysis of prospectively collected multicenter series.

OBJECTIVE

To evaluate the sagittal profile of surgically treated adolescent idiopathic scoliosis (AIS) patients.

SUMMARY OF BACKGROUND DATA

With the increasing popularity of segmental pedicle screw spinal instrumentation, thoracic kyphosis (TK) is often sacrificed to achieve coronal and axial plane correction.

METHODS

Radiographs of AIS patients with a Lenke type 1 deformity and minimum 2-year follow-up after selective thoracic fusion (lowest instrumented vertebra of T11, T12, or L1) were evaluated. Changes in TK were correlated with changes in lumbar lordosis (LL). Patients were divided according to approach (open/thoracoscopic anterior vs. posterior). Analysis of variance was used to compare pre and postoperative radiographic measures.

RESULTS

Two hundred fifty-one patients (age: 14 +/- 2 years) were included. Sixty seven percentages of the patients had anterior surgery (97 open anterior, 71 thoracoscopic) and 33% (83 patients) had posterior spinal fusion. A decrease in postoperative TK was significantly correlated (P < or = 0.001) with a decrease in LL at first erect (r = 0.3), 1 year (r = 0.4) and 2 years (r = 0.4), independent of surgical approach. LL decreased significantly at the first erect regardless of approach (P = 0.003); however, at 2-year postoperative TK and LL were significantly decreased after a posterior approach (P < or = 0.001) when compared with an anterior approach that added kyphosis. The decrease in LL (5.6 degrees +/- 9.7 degrees) was nearly twice the decrease in TK (2.8 degrees +/- 11.4 degrees) in the posterior group at 2-years.

CONCLUSION

Given that thoracic AIS is often associated with a preexisting reduction in TK, ideal surgical correction should address this deformity. Procedures which further reduce TK also reduce LL. It is unclear if the loss of LL from thoracic scoliosis correction will compound the loss of LL that occurs with age and lead to further decline in sagittal balance. With this concern, we recommend a posterior column lengthening and/or an anterior column shortening to achieve restoration of normal TK and maximal LL.

Can posterior-only surgery provide similar radiographic and clinical results as combined anterior (thoracotomy/thoracoabdominal)/posterior approaches for adult scoliosis?

STUDY DESIGN

Retrospective matched cohort analysis.

OBJECTIVE

To determine if posterior-only (post-only) surgical techniques consisting of pedicle screws, osteotomies, transforaminal lumbar interbody fusion, and bone morphogenetic protein-2 may provide similar results as compared anterior (thoracotomy/thoracoabdominal)/posterior surgical approaches for the treatment of adult spinal deformity with respect to correction, fusion rates, or outcomes.

SUMMARY OF BACKGROUND DATA

Combined anterior/posterior (A/P) fusion has traditionally been used to treat many adult scoliosis deformities. Anterior approaches negatively impact pulmonary function and require additional operative time and anesthesia.

METHODS

Twenty-four patients who had A/P fusion for primary adult scoliosis (16 staged, 8 same-day) were matched with a cohort of 24 patients who had post-only treatment. Anterior fusion was performed via a thoracotomy (n = 1)/thoracoabdominal (n = 23) approach. All post-only surgeries were under one anesthesia. Minimum 2-year follow-up included radiographic, clinical, and outcomes data.

RESULTS

There were no significant differences between groups for age, gender, diagnosis, comorbidities, preoperative curve magnitudes, or global balance. Postoperative radiographic correction and alignment were similar for both groups except for thoracolumbar curve percent improvement which was statistically better in the post-only group (P = 0.03). The average surgical time was higher in A/P versus post-only group (11.6 vs. 6.9 hours, P < 0.0001) as was total estimated blood loss (1330 vs. 980 mL, P = 0.04). Hospital length of stay (LOS) was longer in A/P versus post-only group (11.9 vs. 8.3 days, P = 0.03). There were no significant differences between postoperative complications. Revision surgery was performed in 5 A/P and 2 post-only patients. Higher pseudarthrosis rates found in the A/P versus post-only (17 vs. 0%) were not significant (P = 0.11). SRS-30 and Oswestry scores reflected a similar patient assessment before surgery, and improvement between groups at follow-up.

CONCLUSION

Post-only adult scoliosis surgery achieved similar correction to A/P surgery while decreasing blood loss, operative time, length of stay, and avoiding additional anesthesia. Complications, radiographic, and clinical outcomes were similar at over 2-year follow-up.

Risk factors and outcomes for catastrophic failures at the top of long pedicle screw constructs: a matched cohort analysis performed at a single center

STUDY DESIGN

Retrospective review with matched-cohort analysis performed at a single institution.

OBJECTIVE

To determine risk factors and outcomes for acute fractures at the proximal aspect of long pedicle screw constructs.

SUMMARY OF BACKGROUND DATA

Acute fractures at the top of long segmental pedicle screw constructs (FPSC) can be catastrophic. Substantial surgical increase in lordosis may precipitate this problem. In relation to a matched cohort, we postulated that age, body mass index (BMI), and significant correction of lumbar lordosis would increase risk of FPSC and patients with FPSC would have lesser improvements in outcomes.

METHODS

Thirteen patients who sustained FPSC between 2000 and 2007 were evaluated. During this time, 264 patients aged 40 or older had a spinal fusion from the thoracic spine to the sacrum using an all-pedicle screw construct. A cohort of 31 of these patients without FPSC but with all pedicle screw constructs was matched for diagnosis of positive sagittal imbalance, gender, preoperative C7 sagittal plumb, and number of levels fused.

RESULTS

There was a significant difference in age (P = 0.02) and BMI (P = 0.006) between the matched groups. There was no significant difference in preoperative/postoperative C7 plumb or change in lumbar lordosis between groups. Acute neurological deficit developed in 2 patients; both patients improved substantially after revision surgery. Nine patients underwent proximal extension of the fusion. For 7 of the 13 FPSC patients with bone mineral density data (BMD) available, average T score was-1.73; -0.58 for the matched group (10/31 with bone mineral density data) (P = 0.02).

CONCLUSION

Factors that increased the risk of FPSC included obesity and older age. Osteopenia increased the risk as evidenced by BMD (based on 17 patients) and the older age of these patients. There was no statistical difference in clinical improvement between groups based on ODI, but the FPSC group did demonstrate a smaller improvement in ODI score than the matched cohort.

Long adult spinal deformity fusion to the sacrum using rhBMP-2 versus autogenous iliac crest bone graft

STUDY DESIGN

Comparative study.

OBJECTIVE

To compare the radiographic outcome of patients undergoing long spinal deformity surgery to the sacrum/ilium, using either rhBMP-2 without iliac crest bone graft (ICBG) or ICBG without rhBMP-2.

SUMMARY OF BACKGROUND DATA

rhBMP-2 has been shown to be more effective in promoting successful bone union in patients undergoing single level lumbar spinal fusion than ICBG. However, to the best of our knowledge, there are no studies that compare the efficacy of rhBMP-2 versus ICBG in long spinal deformity surgery.

METHODS

To obtain uniform background, we selected patients with adult spinal deformity who underwent primary spinal fusion from the thoracic spine to the sacrum/ilium and had a minimum 2-year follow-up. Fifty-five consecutive patients, consisting of 32 patients who underwent a fusion using ICBG without rhBMP-2 (ICBG group) and 23 patients who underwent a fusion using rhBMP-2 without ICBG (BMP group) were analyzed.

RESULTS

The 2 groups were similar with respect to age, gender, smoking history, comorbidity, and body mass index. The average number of vertebrae fused (11.3 in both groups) and the degree of preoperative deformity (major Cobb angle 58.3 degrees in ICBG group vs. 54.2 degrees in BMP group) were also similar in both groups. All but 2 patients had both anterior and posterior surgery. Both groups were similar in terms of final deformity correction. The average total amount of rhBMP-2 used in the BMP group was 119.2 mg (anterior 11.6 mg/level; posterior 10.0 mg/level). Of the 32 patients in the ICBG group, 9 patients (28.1%) developed a pseudarthrosis, while only 1 of 23 patients (4.3%) in the BMP group developed a pseudarthrosis with the caveat that the follow-up period was shorter in the BMP group (average follow-up of 4.9 vs. 2.7 years).

CONCLUSION

The pseudarthrosis rate in the BMP group compares favorably to pseudarthrosis rate in ICBG group, suggesting that the use of rhBMP-2 without iliac harvesting leads to a competitive fusion rate in long adult spinal deformity surgery, while avoiding ICBG harvest site morbidity.

[Posterior operative correction of idiopathic scoliosis. Value of pedicle screws versus hooks]

Posterior correction and fusion of scoliosis with multisegmental instrumentation systems was developed by Cotrel-Dubousset in the 1980s. Initially correction and instrumentation was performed using hooks only. Later pedicle screws were implemented first for the lumbar and then for the thoracic spine. Nowadays instrumentation based on pedicle screws only is well established for posterior scoliosis surgery. Biomechanical studies demonstrated higher pull-out forces for pedicle than for hook constructs.In clinical studies several authors reported better Cobb angle correction of the primary and the secondary curves and less loss of correction in pedicle screw versus hook instrumentations. Furthermore, pedicle screw instrumentation allows fewer segments to be fused, especially caudally, and thus saving mobile segments. In most of these publications there were no differences in operation time, blood loss and complication rates. In summary, there is better curve correction without an increased risk using multisegmental pedicle screw instrumentation in modern posterior scoliosis surgery.

Comparação do poder de correção do instrumental de Luque-Galveston e do parafuso pedicular no tratamento cirúrgico da escoliose neuromuscular

OBJETIVO: avaliar o poder de correção do parafuso pedicular em comparação ao sistema de Luque-Galveston no tratamento cirúrgico da escoliose neuromuscular. MÉTODOS: foram avaliados 74 pacientes submetidos à artrodese exclusivamente pela via posterior, estendendo-se da região torácica alta ao sacro. Vinte e quatro pacientes foram submetidos à fixação com sistema de Luque-Galveston (Grupo 1) e 50, com parafusos pediculares (Grupo 2). Foram avaliadas as radiografias pré-operatórias, em tração e no pós-operatório imediato e mediu-se o valor da curva principal do período pré-operatório (Cobb pré), na tração (Cobb tração), e no pós-operatório (Cobb pós), e calculou-se a flexibilidade da curva e a correção final. Também foi calculado o Índice de Cincinnati, que leva em consideração a correção final e a flexibilidade (Cincinnati = Correção/Flexibilidade). Os mesmos parâmetros foram calculados para a obliquidade pélvica (OP): OP pré, OP tração, OP pós, Flexibilidade OP, Correção OP e Índice de Cincinnati para OP. RESULTADOS: a média da idade dos pacientes do Grupo 1 foi de 12,24 anos e do Grupo 2, de 16,13 anos (p=0,001). No Grupo 1, a principal doença foi a amiotrofia espinhal (38%) e no Grupo 2, a paralisia cerebral (62%). O ângulo de Cobb pré foi de 76,67º para o Grupo 1 e 85,54º para o Grupo 2. A flexibilidade foi de 45,32% para o Grupo 1 e 39,47% para o Grupo 2. A Correção foi de 63,07% para o Grupo 1 e 59,80% para o Grupo 2. O índice de Cincinnati para o Grupo 1 foi de 1,44 e de 1,71 para o Grupo 2. Quanto à OP, tivemos OP pré de 20,71º para o Grupo 1 e 26,60º para o Grupo 2. A Flexibilidade OP foi de 73,61% para o Grupo 1 e 56,54% para o Grupo 2 (p=0,047). A Correção OP foi de 73,47% para o Grupo 1 e de 72,11% para o Grupo 2. O Índice de Cincinnati da OP foi de 1,09 e 1,49, respectivamente para os Grupos 1 e 2 (p=0,045). CONCLUSÕES: a instrumentação com parafusos pediculares mostrou correção da escoliose semelhante à fixação com Luque-Galveston e maior poder de correção da obliquidade pélvica no tratamento das deformidades neuromuscluares.