Osteotomy of the spine to correct the spinal deformity

Effectiveness and safety of preoperative distraction using modified halo-pelvic Ilizarov distraction assembly in patients with severe kyphoscoliosis

STUDY DESIGN

A 2-year follow-up study.

PURPOSE

To evaluate the effectiveness of modified halo-pelvic Ilizarov distraction assembly in the management of patients with severe kyphoscoliosis.

OVERVIEW OF LITERATURE

Severe and rigid scoliosis curves are always a challenge for operating surgeons. Preoperative correction through halo-pelvic devices successfully minimizes the severity of the curve; however, cumbersome complications are also reported with its use. Modified assembly could be safe for these cases.

METHODS

Patients with severe kyphoscoliosis having coronal Cobb angle >90° were applied with modified halo-pelvic Ilizarov distraction assembly preoperatively. The modified assembly consisted of a pelvic component and halo ring, and distraction was given at the rate of 2-3 mm/day for 6-12 weeks. Complete clinical assessments along with pulmonary function tests were performed, and scoliosis series X-ray images were assessed for coronal and sagittal Cobb angle and other spinopelvic parameters before applying the assembly and during 2 years of follow-up.

RESULTS

Thirty-four patients (age, 9-27 years; male/female ratio of 18:16) were included. The coronal and sagittal Cobb angles were 116°±16.2° and 84°±28.3°, respectively. Correction rates obtained through modified halo-pelvic assembly were nearly 52% (p=0.001) in coronal and 40% (p=0.001) in sagittal Cobb angles, with improvement in height (p=0.001). Apical vertebral translation and coronal balance were also improved significantly (p=0.001). Further improvements in all the parameters were obtained after definitive surgery, with improvements in the forced expiratory volume in 1 second (p =0.002) and forced vital capacity (p=0.001).

CONCLUSIONS

Our modified halo-pelvic Ilizarov distraction assembly can achieve good correction in severe spinal deformities without significant risk to neurology, has fewer complications, and promotes good patient compliance.

Rod Fracture After Pedicle Subtraction Osteotomy Using a Side-Tightening Pedicle Screw System in Consecutive Case Series

OBJECTIVE

The objective of this study was to investigate the incidence and risk factors of rod fractures (RFs) after a single-level lumbar pedicle subtraction osteotomy (PSO) using a side-tightening (ST) pedicle screw system.

METHODS

Fifty-seven consecutive patients who underwent a single-level lumbar PSO for the degenerative sagittal imbalance at a single institution were retrospectively reviewed. All surgeries were performed by a single surgeon using an ST pedicle screw system. Demographic, surgical, and radiographic data were analyzed to investigate the incidence and risk factors for RF.

RESULTS

Seven (12.3%) patients showed RF after PSO. Four patients had bilateral RFs, and 3 patients had unilateral RFs. The location of the RF was at the PSO level in 6 of 7 patients. The ratio of adjacent interbody fusion was significantly different between the group with RF and the group without RF (16.7% vs. 74.0%, P = 0.004). The preoperative segmental angle at the PSO vertebra (-6.1° ± 5.5° vs. -1.7° ± 4.6°, P = 0.049) and postsurgical change in lumbar lordosis (48.4° ± 8.8° vs. 37.8° ± 11.9°, P = 0.033) were significantly different between the 2 groups. Risk factor analysis using stepwise logistic regression analysis revealed that the absence of an adjacent interbody cage (odds ratio = 0.011, 95% confidence interval = 0.000-0.390, P = 0.013) was a significant risk factor.

CONCLUSIONS

The incidence of RF after a single-level lumbar PSO using the ST pedicle screw system was 12.3% in our cohort. The absence of an adjacent interbody cage was a significant risk factor for RF.

Osteotomies for the Treatment of Adult Spinal Deformities: A Critical Analysis Review

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Spinal osteotomies are powerful deformity correction techniques that may be associated with serious complications.

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The anatomical spinal osteotomy classification system proposes 6 grades of resection corresponding to different anatomic bone, disc, facet, and ligament interventions.

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Surgeons should be aware of the nuances of 3-column osteotomies with regard to spinal level selection, construct composition, and posterior column reconstruction and closure techniques.

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There is a global tendency toward avoiding 3-column osteotomies as much as possible because of the growing evidence regarding the effectiveness of posterior column osteotomies and halo-gravity traction.

Surgical strategy for revisional lumbar pedicle subtraction osteotomy to correct fixed sagittal imbalance: The effect of the osteotomy level and iliac screw fixation

BACKGROUND

More caudal osteotomy is believed to lead to greater sagittal correction; however, the osteotomy level and whether or not to use iliac screw fixation (ISF) are topics of on-going debate. The aim of this study was to compare clinical and radiographic outcomes after revisional lumbar pedicle subtraction osteotomy (PSO) for fixed sagittal imbalance (FSI) according to the osteotomy level and ISF.

METHODS

All consecutive patients who underwent revisional PSO (at L3 or L4) for FSI in a single institute from July 2006 to January 2014 were investigated retrospectively. Thirty-eight patients with at least 2-year follow-up were finally included. Clinical outcomes including the visual analogue scale (VAS) and Oswestry Disability Index (ODI) were investigated. Radiographic spinopelvic parameters were analyzed according to the level of PSO, the degree of correction, and the use of ISF.

RESULTS

The mean number of fused segments after PSO was 6.6 ± 1.8. Sagittal vertical axis (SVA) was restored after the surgery (12, 2.5, and 5.2 cm at preoperative, postoperative, and the last follow-up, respectively). PSO was performed at L3 in 16 patients and at L4 in 22 patients. The osteotomy level was not associated with any changes of spinopelvic parameters (pelvic tilt [PT] or lumbar lordosis) or sagittal alignment (T1-pelvic angle [TPA] or SVA). However, better TPA restoration was achieved with more osteotomy resection angle (P = 0.031). ISF group showed significant improvement in postoperative pelvic orientation (PT and ratio of PT to pelvic incidence) which was maintained until the last follow-up.

CONCLUSIONS

Although postoperative sagittal alignment was different in FSI patients according to the osteotomy level, pelvic orientation improved in ISF group. Also, the degree of correction showed significant associations with sagittal alignment. When performing revisional PSO for FSI, spine surgeon should carefully consider how to correct rather than where to do the osteotomy, and the role of ISF.

Surgical site infection following surgery for spinal deformity: About 102 patients

INTRODUCTION

Complex spinal surgery is known to be at risk of complications. Surgical site infection is a serious complication in spine surgery and its frequency is significantly increased in adult spinal deformity correction. The aim of this study is to identify patients' characteristics and risk factors of surgical site infection (SSI) following an osteotomy.

METHODS

This is a single-center retrospective study of patients who underwent an osteotomy between January 2015 and December 2017. Surgical site infection diagnosis was based upon patient's clinical evidence of infection, biologic parameters, microbiological criteria and/or image findings.

RESULTS

In total, 102 patients were eligible and 70 were women (68.6%). Mean age was 65 years old (27-83 years) and mean body mass index (BMI) was 26.14kg.m^-2 (18.4-44.1). Eleven patients were in the SSI group and 91 in the No-SSI group. The mean Schwab grade was 1.5 (1-4) in the SSI group vs. 1.4 (1-5) in the No-SSI group (P=0.435). The mean operative time was on 201.9 minutes (67-377). Mean length of stay was 20.6 days (10-73) in the SSI group vs. 15 days (5-44) in the No-SSI group (P=0.041). Favorable outcome was found in 10 patients (90.9%) in the SSI group.

CONCLUSION

Correction surgery for adult spinal deformity with osteotomies carries a high risk of complications specially SSI. Identification of risk factors, prevention and medical management of SSI should be well assessed.

State of the art review: Vertebral Osteotomies for the management of Spinal Deformity

Spinal deformity is a complex condition caused by various etiologies (degenerative, neuromuscular, congenital, developmental, traumatic, neoplastic, idiopathic) leading to clinical deformity, axial back pain, and neurologic deficits. Patients presenting with severe deformities require vertebral osteotomies to achieve the necessary curve correction for radiographic and clinical improvement. The three major vertebral osteotomy techniques commonly used at this time are the posterior column osteotomy (PCO), pedicle subtraction osteotomy (PSO), and vertebral column resection (VCR). The different vertebral osteotomies have unique merits and pitfalls that need to be addressed during preoperative planning to achieve maximum benefit while limiting or avoiding possible complications. The more difficult vertebral osteotomies have a steeper learning curve and requires extensive pre, intra and postoperative management of the patient. This review will aim to discuss the indications, surgical techniques, and clinical outcomes for each of these different vertebral osteotomy techniques with illustrative cases.

Medical optimization of modifiable risk factors before thoracolumbar three-column osteotomies: an analysis of 195 patients

PURPOSE

To determine the rate of preoperative modifiable laboratory abnormalities (both major and minor) and the association with early postoperative medical and surgical complications.

METHODS

All patients undergoing thoracolumbar three-column osteotomy between 2013 and 2016 with preoperative laboratory data were identified. Potential preoperative modifiable laboratory abnormalities (major and minor) were assessed including hyponatremia (sodium < 130 and < 135 mEq/L), anemia (hematocrit < 25% and < 30%), renal insufficiency (creatinine ≥ 1.8 and ≥ 1.2 mg/dL), coagulopathy (INR ≥ 1.8 and ≥ 1.2), and hypoalbuminemia (albumin < 2.5 and < 3.5 g/dL). Multivariate logistic regression was used to determine associations with 30-day complications after controlling for possible confounding factors.

RESULTS

A total of 195 patients were identified. The rates of major and minor preoperative laboratory abnormalities were 7.7% and 31.3%, respectively. The rates of serious medical, minor medical, and surgical complications over 30-days were 6.7%, 21.5%, and 10.3%, respectively. In multivariate analysis the presence of major preoperative laboratory abnormalities had a significant association with serious medical complications (odds ratio [OR] 77.8, P < 0.001), and minor medical complications (OR 13.3, P < 0.001), but not surgical complications (P = 0.243). The presence of minor preoperative laboratory abnormalities had a significant association with serious medical complications (OR 10.4, P = 0.041) and minor medical complications (OR 2.4, P = 0.045), but not surgical complications (P = 0.490).

CONCLUSIONS

While major laboratory abnormalities had a strong association with complications, even minor modifiable laboratory abnormalities had a significant association with both serious and minor medical complications.

Two-Level Osteotomy for the Corrective Surgery of Severe Kyphosis From Ankylosing Spondylitis: A Retrospective Series

STUDY DESIGN

Retrospective study.

OBJECTIVE

To describe the treatment results of patients with severe ankylosing spondylitis (AS) kyphosis who underwent two-level osteotomy and correction surgery.

SUMMARY OF BACKGROUND DATA

The best solution for the fixed kyphotic deformity of AS is corrective osteotomy. Many osteotomy options are available: pedicle subtraction osteotomy (PSO), Smith-Peterson osteotomy (SPO), and vertical column resection (VCR). These procedures all provide multiplanar deformity correction. Nevertheless, when the AS deformity is severe, an additional osteotomy site to get more correction, achieve more ideal, and smooth curvature of the spine than single osteotomy.

METHODS

From May, 2008 to August, 2016, 19 patients of severe AS kyphosis underwent two-level spinal osteotomy and correction surgery. The patients had an average kyphosis angle greater than 90°. The radiological features and clinical evaluation, including Oswestry Disability Index (ODI), visual analog scale (VAS), and Scoliosis Research Society (SRS)-22 components were assessed before surgery and at follow-up. The patients underwent either one-level PSO combined with one-level SPO (n = 9) or two-level PSO (n = 10).

RESULTS

The height was increased after surgery in all patients (P < 0.05). The median follow-up was 24 months. The kyphosis angle improved from 92.0 ± 16.6° to 30.0 ± 17.2°. The chin-brow vertical angle improved from 37.6 ± 19.2° to -0.6 ± 2.5°. The sacral slope improved from 3.9 ± 11.8° to 21.7 ± 7.4°. Sagittal imbalance improved from 241.4 ± 115.3 mm to 74.6 ± 48.5 mm (P < 0.05). Lumbar lordosis improved from -3.9 ± 20.8° to 29.4 ± 14.1° (all P < 0.05). There were significant improvements in the ODI, VAS, and all components of SRS-22 (all P < 0.05). All patients with pseudarthrosis (n = 5) underwent PSO + SPO and achieved satisfactory results. Six complications were observed perioperatively, but without permanent sequelae.

CONCLUSION

Two-level osteotomy and correction procedure can achieve satisfactory results in severe AS kyphosis. PSO + SPO could be a good option for patients with pseudarthrosis because of relatively easier and faster operation.

LEVEL OF EVIDENCE

4.

Acute Normovolemic Hemodilution in Spinal Deformity Surgery

Objective  To prospectively compare the clinical and laboratorial aspects of patients undergoing spine deformity surgery, using the acute normovolemic hemodilution technique with tranexamic acid, versus a control group with tranexamic acid alone, and to evaluate the influence of hemodilution in intraoperative bleeding and the need for homologous transfusion.

Materials and Methods  Comparative prospective study with patients aged between 12 and 65 years undergoing spine deformity surgery with the acute normovolemic hemodilution technique associated with tranexamic acid versus a control group to which only tranexamic acid (15 mg/kg) was administered. Laboratorial exams were performed and analyzed in three different moments.

Results  A total of 30 patients were included in the present study: 17 in the hemodilution group, and 13 in the control group. The mean duration of the surgery in the hemodilution group was longer. The number of levels submitted to surgery ranged from 7 to 16 in the hemodilution group, and from 4 to 13 in the control group. Osteotomy, predominantly of the posterior kind, was performed in 20 patients. There was more intraoperative bleeding in the control group. All patients were stable during the procedures. Only 6 participants needed homologous blood transfusion, mostly from the control group ( p  > 0.05).

Conclusion  There was no significant difference between the two groups regarding the need for blood transfusion and intraoperative bleeding. The severity of the deformity was the main determinant for homologous blood transfusion.

Surgical treatment of thoracolumbar spinal tuberculosis-a multicentre, retrospective, case-control study

BACKGROUND

The purpose of this multicentre, retrospective study was to evaluate the safety and efficacy of different surgical approaches for treating thoracolumbar tuberculosis.

METHODS

This study reviewed 132 patients with thoracolumbar tuberculosis in six institutions between January 1999 and January 2015 surgically treated by an anterior-only approach (n = 22, group A), an anterior combined with posterior approach (n = 79, group B), and a posterior-only approach (n = 31, group C). All patients were treated with standard antituberculosis drugs pre- and postoperatively and were followed regularly after surgery. Clinical symptoms, nerve function, and the erythrocyte sedimentation rate were observed, and kyphosis correction and bone fusion were evaluated by X-ray or computed tomography.

RESULTS

At the last follow-up, all patients had achieved bone fusion, relief from pain, and neurological recovery. The Cobb angle was improved; however, the Cobb angle showed a degree of loss at the final follow-up after all three surgical approaches. Further comparisons revealed a difference in angle loss at the final follow-up among the three groups; groups B and C were superior to group A in maintenance of the correction. The posterior-only approach was characterized by a shorter operative time and reduced blood loss.

CONCLUSIONS

Surgery by a posterior-only approach is superior to that by an anterior-only approach and anterior combined with posterior approach in terms of permanent kyphosis correction and spinal stability maintenance. Therefore, we recommend surgery by a posterior-only approach as the optimized treatment for thoracolumbar tuberculosis if the indications for this treatment are met.

S1 Pedicle Subtraction Osteotomy in Sagittal Balance Correction. A Feasibility Study on Human Cadaveric Specimens

BACKGROUND

A cadaveric feasibility study was carried out. Osteotomies to correct fixed sagittal imbalance are usually performed at L₃/ L₄.

OBJECTIVE

To investigate the feasibility of S₁ pedicle subtraction osteotomy to correct spinal deformity and spinopelvic parameters, achieving better results with more limited exposure. The data obtained will allow a fixation construct specific for this osteotomy to be designed.

METHODS

S₁ pedicle subtraction osteotomy was performed on 12 cadaveric specimens. Baseline and postprocedural computed tomography and biomechanical studies were performed. Data were analyzed with a fixation system SolidWorks model, and the redesigned fixation construct was described and analyzed with an ANSYS model.

RESULTS

S₁ pedicle subtraction osteotomy is technically feasible. The fixation can be achieved with L₄, L₅, and iliac screws connected with bars. The system can be reinforced with a polyetheretherketone cage placed anteriorly in the S₁ body osteotomy site, a cross-connecting bar, a double iliac screw, or an anterior interbody cage placed at the L₅-S₁ disc. The fixation strength is improved by angulating the iliac rod channel 10°, adding a semi-sphere to the locking screw contact surface and 2 fins to its saddle. The redesigned construct showed suitable stress and deformation levels, achieving the expected biomechanical requirements.

DISCUSSION

Compared with surgery on higher levels, S₁ pedicle subtraction osteotomy allows greater correction with shorter fixation, because the osteotomy is performed at a more caudal level, modifying the spinopelvic parameters.

CONCLUSIONS

S₁ pedicle subtraction osteotomy is technically feasible. Finite element analysis results indicate that it has appropriate biomechanical properties.

Alphabet Soup: Sagittal Balance Correction Osteotomies of the Spine-What Radiologists Should Know

Global sagittal malalignment has been demonstrated to have correlation with clinical symptoms and is a key component to be restored in adult spinal deformity. In this article, various types of sagittal balance-correction osteotomies are reviewed primarily on the basis of the 3 most commonly used procedures: Smith-Petersen osteotomy, pedicle subtraction osteotomy, and vertebral column resection. Familiarity with the expected imaging appearance and commonly encountered complications seen on postoperative imaging studies following correction osteotomies is crucial for accurate image interpretation.

Incidence, influencing factors, and prognostic impact of intraoperative massive blood loss in adolescents with neuromuscular scoliosis: A STROBE-compliant retrospective observational analysis

Factors influencing massive blood loss for neuromuscular scoliosis (NMS) patients.Despite advances in surgical and anesthetic techniques, scoliosis surgery is still associated with intraoperative massive blood loss, which can result in postoperative mortality and morbidity. The aim of this study was to assess the incidence, influencing factors, and prognostic impact of intraoperative massive blood loss in adolescents with NMS.A retrospective review of adolescents who underwent posterior spinal instrumentation and fusion for NMS was performed. Perioperative variables and data were recorded. Massive blood loss was defined as an estimated blood loss that exceeds 30% of total blood volume.We obtained data for 114 patients, of whom 63 (55%) had intraoperative massive blood loss. Compared with those without, patients with massive blood loss were more likely to be older, have lower body mass indexes (BMIs), larger Cobb angles, more fused levels, more osteotomy procedures, and prolonged duration of operation. Logistic regression analysis identified the number of fused levels to be more than 12 (P = 0.003, odds ratio = 6.614, 95% confidence interval [CI]: 1.891-23.131), BMI lower than 16.8 kg/m (P = 0.025, odds ratio = 3.293, 95% CI: 1.159-9.357), age greater than 15 years (P = 0.014, odds ratio = 3.505, 95% CI: 1.259-9.761), and duration of operation longer than 4.4 hours (P = 0.016, odds ratio = 3.746, 95% CI: 1.428-9.822) as influencing factors. Patients with massive blood loss are associated with more intraoperative colloids infusion and blood transfusions (red blood cell and fresh frozen plasma), as well as postoperative drainage volume.In adolescents with NMS who underwent posterior spinal instrumentation and fusion operations, intraoperative massive blood loss is common. The number of fused levels, BMI, age, and duration of operation are factors influencing intraoperative massive blood loss.

Treatment of kyphosis in ankylosing spondylitis by osteotomy through the gap of a pathological fracture: a retrospective study

Background

Surgical interventions are commonly advocated for correcting kyphotic deformities and relieving severe back pain in ankylosing spondylitis (AS) patients. The aim of this study was to evaluate the clinical outcome of osteotomy performed through the gap of a pathological fracture for the treatment of kyphosis in ankylosing spondylitis and to introduce the key points of this novel surgical approach.

Methods

From January 1, 2010, to December 31, 2014, 13 consecutive AS patients who were treated with osteotomy through the fracture gap were retrospectively reviewed. Patients underwent the radiographic assessment of sagittal balance parameters. Visual analog scale (VAS) scores were used to assess improvement in back pain.

Results

The average follow-up time was 2 years and 1 month. The median operation time was 280 min (range, 220–460 min). The mean blood loss was 1100 mL (range, 820–1300 mL). No major acute complications such as death or complete paralysis occurred. There were no neurologic complications or cerebrospinal fluid leaks in any patient. One patient had postoperative wound infection, which subsided after a switch of antibiotics. The global kyphosis Cobb angle of patients decreased from the preoperative 55.8° ± 11.0° to 23.2° ± 6.7° (P < 0.001) after surgery. The C7 plumb line was used to assess global balance; its relationship with the posterosuperior corner of the sacrum decreased from 166 ± 37 mm to 111 ± 20 mm (P < 0.001). The thoracolumbar kyphosis Cobb angle decreased from 51.0° ± 9.9° to 21.6° ± 11.0° (P < 0.001). VAS scores for back pain decreased from 7.2 ± 1.2 to 2.1 ± 1.1 (P < 0.001). Lumbar lordosis increased from 5.7° ± 23.2° to 10.5° ± 29.2° (P = 0.001).

Conclusions

Osteotomy through the pathological fracture gap is a safe and effective surgical procedure for kyphosis correction and improvement of back pain in AS patients with pathological fractures. A significant kyphosis correction and improvement of back pain can be achieved with this surgical procedure.

Predictive Model for Cervical Alignment and Malalignment Following Surgical Correction of Adult Spinal Deformity

STUDY DESIGN

Retrospective review of prospective multicenter database.

OBJECTIVE

Use predictive modeling to identify patient characteristics, radiographic, and surgical variables that predict reaching an outcome threshold of suboptimal cervical alignment after adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

Cervical deformity (CD) after ASD correction has been defined with the following criteria: T1S-CL>20°, C2-C7 SVA>40 mm, and/or C2-C7 kyphosis >10°. While studies have analyzed CD predictors, few have defined and identified predictors of optimal cervical alignment after thoracolumbar surgery.

METHODS

Inclusion criteria were surgical ASD patients with baseline and 2-year follow-up. Postoperative cervical alignment (CA) and malalignment (nonCA) at 2 years was defined with the following radiographic criteria: 0°≤T1S-CL≤20°, 0 mm≤C2-C7 SVA≤40 mm, or C2-C7 lordosis >0°. Three thresholds classifying malalignment were defined: (T1) missing 1 criterion, (T2) missing 2 criteria, (T3) missing 3 criteria. Multivariable logistic stepwise regression models with bootstrap resampling procedure were performed for demographic, surgical, and radiographic variables. The model was validated with receiver operative characteristic and area under the curve.

RESULTS

Two hundred twenty-five surgical ASD patients were included. At 2 years 208 patients (92.4%) were grouped as CA in T3, while 17 (7.6%) were nonCA. Patients were similar in age (CA: 56.10 vs. nonCA: 55.78 years, P = 0.150), BMI (CA: 26.93 vs. nonCA: 26.94 kg/m, P = 0.716), and sex (CA: 76.5% vs. nonCA: 87.0%, P = 0.194). The final predictive model included C2 slope, C2-T3 CL, T1S-CL, C2-C7 CL, Pelvic Tilt, C2-S1 SVA, PI-LL, and Smith-Peterson osteotomies number. In this model (area under the curve 89.22% [97.49-80.96%]), the following variables were identified as predictors of nonCA: increased Smith-Peterson osteotomies use (OR: 1.336, P = 0.017), and C2-T3 angle (OR: 1.048, P = 0.005).

CONCLUSION

This study created a statistical model that predicts poor 2-year postoperative cervical malalignment in ASD patients. T3 (patients not meeting all three alignment criteria) was the most effective threshold for modeling nonCA, and included increased baseline C2-T3 angle and increased Smith-Peterson osteotomies during index.

LEVEL OF EVIDENCE

3.

A proposed classification system for guiding surgical strategy in cases of severe spinal deformity based on spinal cord function

PURPOSE

Spinal cord function classification systems are not useful for guiding surgery in patients with severe spinal deformities. The aim of this study is to propose a classification system for determining a surgical strategy that minimizes the risk of neurological dysfunction in patients with severe spinal deformities.

METHODS

The records of 89 patients with severe spinal deformities treated with vertebral column reconstruction from 2008 to 2013 were retrospectively analyzed. Based on neurophysiological monitoring, magnetic resonance imaging, and neurological symptoms patients were categorized into three groups: group A, normal spinal cord, normal evoked potentials and no neurological symptoms; group B, spinal cord abnormalities and/or abnormal evoked potentials but no neurological symptoms; group C, neurological symptoms with or without spinal cord abnormalities/abnormal evoked potentials. Outcomes and complications were compared between the groups.

RESULTS

A total of 89 patients (51 male, 38 female) were included with 47 (52.8 %), 16 (18.0 %), and 26 (29.2 %) patients in groups A, B and C, respectively, and a mean follow-up 34.5 months. There were no differences in age, gender, average preoperative scoliosis, and kyphosis among three groups, but there were differences with respect to the causes of severe spinal deformity and the corrective rate of scoliosis and kyphosis. Changes in intraoperative evoked potentials were different in these three types according to this new classification, and the recovery rates of changes in the three groups were 71.1, 50.0, and 14.1 %, respectively. Postoperative spinal cord injury was positively related to intraoperative changes of evoked potentials.

CONCLUSION

The classification system may be useful for guiding surgical decisions in patients with severe spinal deformities to minimize the risk of neurological complications.

Comparison of Clinical and Radiological Improvement Between the Modified Trephine and High-speed Drill as Main Osteotomy Instrument in Pedicle Subtraction Osteotomy

High-speed drill is the main osteotomy instrument in pedicle subtraction osteotomy (PSO) currently. Considering the long duration of surgery, the large amount of blood loss, and the high incidence of neurovascular injury, the osteotomy procedure is challenging. Use of trephine for the osteotomy displays high efficiency by shortening surgery time and reducing blood loss in anterior cervical corpectomy and fusion. However, the potential risk of neurological injury is high. We modified the trephine by adding locking instrument, when the serrated top of the trephine reaches the tip of the probe; the locking instrument on the probe restricts the trephine and improves security during the osteotomy procedure.The aim of this study was to compare the clinical and radiological improvement between the modified trephine and high-speed drill as main osteotomy instrument in PSO.From February 2009 to 2013, 50 patients with severe thoracolumbar kyphotic deformity caused by old compressive vertebrae were prospectively reviewed. All patients were randomly assigned to the experimental group (27 patients received PSO with modified trephine) and the control group (23 patients received PSO with high-speed drill). The clinical records were reviewed and compared for surgical time, operative blood loss, functional improvement (Oswestry Disability Index), and pain relief (visual analog scale). The radiological records were reviewed and compared for correction of kyphotic deformity postoperatively and correction loss at 2-year follow-up.All patients successfully finished the PSO procedure, and got satisfactory kyphotic deformity correction and overall function improvement. The surgery time was shorter in the experimental group than that in the control group (132.7 ± 12.6 vs 141.7 ± 16.7 min; P = 0.03). No significant difference was found in blood loss (882.9 ± 98.9 mL vs 902.2 ± 84.9 mL; P = 0.47) or correction of the kyphotic angle (33.4 ± 3.4° vs 32.1 ± 2.5°, P = 0.13) postoperatively between the 2 groups. At 24-month follow-up, no difference was discovered in loss of the correction (4.9 ± 1.6° vs 4.5 ± 1.6°; P = 0.42), change of Oswestry Disability Index (49.4 ± 6.2% vs 48.2 ± 4.2%; P = 0.44), or in back pain relief (6.2 ± 1.4 vs 6.4 ± 1.2 min; P = 0.51) between the 2 groups. No internal fixation related complication occurred and bony fusion was detected in lateral X-ray in all patients. In the control group, 2 patients had transient nerve root deficit, 14 patients at 3-month follow-up and 3 patients at 2-year follow-up experienced graft donor site morbidity, and pain killer medicine was always required.In conclusion, the modified trephine obviously shortens surgery time, and prevents graft donor site morbidity when compared to a high-speed drill. The learning curve for using the modified trephine in PSO procedure is short.

A biomechanical comparison of 360° stabilizations for corpectomy and total spondylectomy: a cadaveric study in the thoracolumbar spine

Background

To date, there has been no adequate biomechanical model that would allow a quantitative comparison in terms of stability/stiffness between a corpectomy with the posterior column preserved and a total spondylectomy with the posterior column sacrificed. The objective of this study was to perform a biomechanical comparison of 360° stabilizations for corpectomy and total spondylectomy, using the human thoracolumbar spine.

Methods

Five human cadaveric thoracolumbar spines (T8-L2) were tested according to the following loading protocol: axial compression, flexion, extension, lateral bending to the right and left, and axial rotation to the right and left. This loading protocol was applied three times. Each specimen was tested intact, after corpectomy, and after total spondylectomy. The relative stiffness of each motion segment was determined for each test.

Results

There was no significant difference in stiffness after reconstruction of total spondylectomy versus corpectomy in our thoracolumbar model. Our construct consisted of an anterior cage and four-level pedicle screw instrumentation (two above and two below) and provided similar stiffness in both models. Despite the additional bone resection in a total spondylectomy versus corpectomy, the constructs did not differ biomechanically. Additionally, there was no significant difference in stiffness between the intact specimen and either reconstruction model.

Conclusions

A classic corpectomy, which leaves the posterior column intact, is no better in terms of stability/stiffness than a total spondylectomy carried out using a shorter cage, followed by compression using posterior instrumentation.

Three Different Methods in Deformity Correction of Degenerative Flat Back: A Single Surgeon's Experience with 64 Consecutive Cases

Study Design

Retrospective study.

Purpose

To evaluate the radiological and clinical results of three different methods in the deformity correction of a degenerative flat back.

Overview of Literature

There are no comparative studies about different procedures in the treatment of degenerative flat back.

Methods

Sixty-four patients who consecutively underwent corrective surgery for degenerative flat back were reviewed. The operations were performed by three different methods: posterior-only (group P, n=20), one-stage anterior-posterior (group AP, n=12), and two-stage anterior-posterior with iliac screw fixation (group AP-I, n=32). Medical and surgical complications were examined and radiological and clinical results were compared.

Results

The majority of medical and surgical complications were found in group AP (5/12) and group P (7/20). The sagittal vertical axes were within normal range immediately postoperatively in all groups, but only group AP-I showed normal sagittal alignment at the final follow-up. Postoperative lumbar lordosis was also significantly higher in group AP-I than in group P or group AP and the finding did not change through the last follow-up. The Oswestry disability index was significantly lower in groups AP and AP-I than in group P at the final follow-up. Meanwhile, the operating time was the longest in group AP-I, and total amount of blood loss was larger in group AP-I and group AP than in group P.

Conclusions

Anterior-posterior correction showed better clinical results than posterior-only correction. Two-staged anterior-posterior correction with iliac screw fixation showed better radiological results than posterior-only or one-staged anterior-posterior correction. Two-staged anterior-posterior correction with iliac screw fixation also showed a lower complication rate than one-staged anterior-posterior correction.

Analysis of 17 cases of posterior vertebral column resection in treating thoracolumbar spinal tuberculous angular kyphosis

OBJECTIVE

This study aims to explore the efficacy and safety of posterior vertebral column resection (PVCR) in treating thoracolumbar spinal tuberculous angular kyphosis (TSTAK).

METHODS

From January 2008 to January 2012, 17 TSTAK patients were treated surgically, including five males and 12 females, with an average age of 23.6 years, among five cases who had the kyphotic apical vertebrae located at the thoracic vertebrae, ten cases were located at the thoracolumbar segment, and two cases were located at the lumbar vertebrae. The kyphotic Cobb angle was measured in the preoperative, postoperative, and final follow-up, respectively, and the nerve function ASIA classification was assessed.

RESULTS

The mean operative time was 364 min; the average intraoperative blood loss was 2,218 ml; and the average intraoperative blood transfusion was 1,863 ml. Among the five patients with the preoperative nerve function as grade D, four of them recovered to grade E. The preoperative average Cobb angle was 81.3° ± 12.8°, while the postoperative average Cobb average was 17.3° ± 3.6°; while it was significantly improved than the preoperative (P < 0.01), the average kyphosis correction rate was 68.7% ± 6.5%; the postoperative average follow-up was 18.7 months, with an average correction loss as 3.3°.

CONCLUSION

PVCR could be safely and effectively used in TSTAK.

Comparison of pedicle subtraction and Smith-Petersen osteotomies in correcting thoracic kyphosis when closed with a central hook-rod construct

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

To demonstrate the effectiveness of hook-rod constructs in closing thoracic osteotomies safely and effectively.

SUMMARY OF BACKGROUND DATA

The outcomes of hook-rod instrumentation in osteotomies for the correction of kyphosis at the lumbar region of the spine have been described. Little literature exists on the outcomes at the thoracic level.

METHODS

The radiographs and clinical scores of 38 patients who underwent pedicle subtraction osteotomy or Smith-Petersen osteotomy in the thoracic spine with the osteotomies closed using a central rod were retrospectively reviewed. Measurements included osteotomy angle, thoracic kyphosis (T2-T12), and maximum kyphosis. Perioperative and long-term complications were reviewed.

RESULTS

Thirty-eight patients underwent thoracic level osteotomies. There were 8 males and 30 females with a mean age of 51.9 years (range, 18-76 yr) at the time of surgery. The mean construct length was 13.2 levels (4-25). Kyphosis correction was equal in the 2 groups. In the pedicle subtraction osteotomy group, a mean of 24.7° (4°-47°) correction was obtained through the osteotomies compared with 24.0° (9°-65°) in the Smith-Petersen osteotomy group. Correction per osteotomy was 23.7° (4°-47°) in the pedicle subtraction osteotomy group compared with 11.8° (2.8°-46.0°) in the Smith-Petersen osteotomy group. No difference in the amount of correction achieved at the different regions of the thoracic spine was observed with either type of osteotomy with central rod closure.

CONCLUSION

Central hook-rod constructs provide a safe and effective means of closing thoracic osteotomies and result in good correction of rigid sagittal plane deformities.

LEVEL OF EVIDENCE

4.

Effects of surgical correction of neuromuscular scoliosis on gastric myoelectrical activity, emptying, and upper gastrointestinal symptoms

OBJECTIVES

Gastrointestinal complications are frequent after surgical correction of neuromuscular scoliosis, but the effects of scoliosis surgery on gastric function and upper gastrointestinal symptoms over the long term are unknown.

METHODS

Thirty-one children (16 spastic, 15 flaccid patients) who underwent surgical correction of neuromuscular scoliosis were included in a prospective follow-up study. Median (range) age at surgery was 14.9 (5-20) years and follow-up time 4.3 (2-8) years. Electrogastrography (n=28), gastric emptying scintigraphy (n=17), and structured upper gastrointestinal symptoms questionnaire (n=26) were evaluated before and after surgery. The results were related to patients' clinical state, type and extent of corrective spinal surgery, and gastrointestinal complications.

RESULTS

The median main scoliosis curve of 81 degrees (51-129 degrees) was corrected to 25 degrees (1.0-85 degrees) after surgery. In electrogastrogram, power ratio increased from preoperative 1.4 (0.30-11) to postoperative 6.2 (1.2-26) in the spastic group (P=0.008), whereas in the flaccid group, power ratio remained unchanged at 2.2 (0.1-17). Patients with prolonged postoperative paralytic ileus had the most substantial increase in gastric power ratio (P=0.038). Correction of sagittal spinal balance correlated with increased postprandial normogastric activity after surgery (R=0.459; P=0.004). The gastric emptying results, upper gastrointestinal symptoms, and body mass index were not significantly altered after scoliosis surgery.

CONCLUSIONS

Gastric myoelectrical power increased after surgical correction of spastic neuromuscular scoliosis and was associated with prolonged postoperative paralytic ileus. Correction of poor, stooped spinal balance improved gastric myoelectrical activity. The net effect of scoliosis surgery on gastric emptying, upper gastrointestinal symptoms, and clinical nutritional state was minimal.

Partial pedicle subtraction osteotomy as an alternative option for spinal sagittal deformity correction

STUDY DESIGN

A retrospective study.

OBJECTIVE

To describe the technique of a partial pedicle subtraction osteotomy (PPSO) and to report on the clinical and radiological outcomes.

SUMMARY OF BACKGROUND DATA

Numerous corrective osteotomy techniques have been reported. Until now, there has been no reported method that can achieve a correction angle between those of the Smith-Petersen osteotomy and pedicle subtraction osteotomy as a posterior closing osteotomy that can be safely performed on the thoracic spine.

METHODS

A total of 38 patients aged between 31 and 72 years, who underwent PPSO for spinal sagittal deformity correction were enrolled in this study. The mean postoperative follow-up period was 30.1 months (range, 24-36 mo). The assessments included the Oswestry Disability Index scores, immediate postoperative and 2-year postoperative correction angles, correction loss, pseudoarthrosis, and complications.

RESULTS

There were 6 patients who underwent PPSO alone and 32 patients who underwent PPSO combined with at least one other surgical procedure (PSO in 16 patients, anterior lumbar interbody fusion in 12 patients, and Smith-Petersen osteotomy in 4 patients). The level of the osteotomy was T10 in 6 patients, T11 in 15 patients, T12 in 10 patients, 1 in 4 patients, L2 in 2 patients, and L3 in 1 patient. There were significant improvements in the overall Oswestry Disability Index scores (P = 0.001). The mean postoperative correction angle immediately after the PPSO was 18.8° (range, 12.4°-26.1°) and the mean postoperative correction angle at 2 years was 18.4° (range, 11.9°-25.7°). There was no significant loss of correction found during the 2-year follow-up. There was also no pseudoarthrosis or neurological complications.

CONCLUSION

PPSO had resulted in intermediate correction rates between those of Smith-Petersen osteotomy and PSO. PPSO is considered to be a safe and reliable procedure for patients with spinal sagittal deformities even at the thoracic spine level.

LEVEL OF EVIDENCE

4.

Anterior elongation as a minimally invasive alternative for sagittal imbalance-a case series

BACKGROUND

Degenerative and iatrogenic conditions may lead to flat back or even to kyphotic deformity, and sagittal imbalance can cause significant clinical impairment. Minor imbalance cases are usually treated with conservative care. Among currently popular surgical techniques for the correction of sagittal imbalance are posterior-based procedures, which are associated with access-related risks (mostly neurological) and postoperative morbidity risks.

PURPOSE

This study aims to report a minimally invasive lateral approach using hyperlordotic cages in the treatment of mild sagittal imbalance. Radiological correction, clinical improvement, and safety will be analyzed.

METHODS

Eight patients (mean age 71.8 years, SD 7.8; mean BMI 27.5, SD 2.3) with symptomatic sagittal imbalance were retrospectively reviewed. Eight cases were treated by anterior interbody fusion with lordotic cages. A minimally invasive lateral retroperitoneal approach was used in the surgical procedures, with or without percutaneous pedicle screw supplementation.

RESULTS

No major complications occurred and just one case needed revision for direct decompression. Clinical outcomes Visual Analog Scale score changed from 88 at preoperative visit to 51 at 1-week visit, and Oswestry Disability Index score decreased from 82 at preoperative visit to 44 at 6-week visit. The 6-month radiological assessment revealed improvement in spinopelvic parameters: Focal lordosis improved from 2.3° ± 7.7 to 27.1° ± 6.7. Sagittal vertical alignment improved from 11.7 ± 5.3 to 6.2 ± 4.0 cm. Preoperative sacral slope improved from 20.1° ± 5.8 to 29.4° ± 10.3 and preoperative pelvic tilt improved from 35.2° ± 5.2 to 23.8° ± 4.3. Short-term results indicate that the minimally invasive lateral approach can be applied to the treatment of mild sagittal imbalance, with special advantage in elderly patients or those in which posterior approaches are relatively contraindicated.

Impact of spinopelvic alignment on decision making in deformity surgery in adults

Sagittal spinal misalignment (SSM) is an established cause of pain and disability. Treating physicians must be familiar with the radiographic findings consistent with SSM. Additionally, the restoration or maintenance of physiological sagittal spinal alignment after reconstructive spinal procedures is imperative to achieve good clinical outcomes. The C-7 plumb line (sagittal vertical axis) has traditionally been used to evaluate sagittal spinal alignment; however, recent data indicate that the measurement of spinopelvic parameters provides a more comprehensive assessment of sagittal spinal alignment. In this review the authors describe the proper analysis of spinopelvic alignment for surgical planning. Online videos supplement the text to better illustrate the key concepts.