Coronal decompensation produced by Cotrel-Dubousset "derotation" maneuver for idiopathic right thoracic scoliosis

Long-term Radiographic and Clinical Outcomes After Selective Thoracic Fusion for Adolescent Idiopathic Scoliosis With Lenke 1C Curve

BACKGROUND

Despite the promising results with selective thoracic fusion (STF) in patients with adolescent idiopathic scoliosis (AIS) of the Lenke 1C curve, postoperative coronal imbalance and progression of the unfused lumbar curve have been concerns in long-term follow-up. In this study, we aimed to investigate the radiographic and clinical outcomes after STF for AIS with Lenke 1C curve with long-term follow-up.

METHODS

A total of 30 patients with AIS with Lenke 1C curves who underwent STF between 2005 and 2017 were included. Minimum follow-up duration was 5 years. Time-dependent changes in radiographic parameters were investigated preoperatively, immediately postoperatively, and at the last follow-up. In addition, radiographic adverse events such as coronal decompensation (CD), lumbar decompensation (LD), distal adding-on (DA) phenomenon, and trunk shift were evaluated at the last follow-up. The Scoliosis Research Society-22 score was used for clinical outcome evaluation.

RESULTS

The mean age at the time of surgery was 13.8 years. The mean follow-up duration was 6.7 ± 0.8 years. The main thoracic curve significantly improved from 57 degrees to 23 degrees (60% correction), and the thoracolumbar/lumbar curve significantly improved from 47 degrees to 28 degrees (41% correction). Coronal balance was 15 mm after surgery but significantly improved to 10 mm at the last follow-up (P = 0.033). At the final follow-up, 11 patients (37%) sustained at least one of the radiographic adverse events: CD in 5 patients (17%), LD in 3 (10%), DA in 4 (13%), and trunk shift in 3 (10.%). However, there were no cases requiring revision surgery. In addition, there were no significant differences in any items or total Scoliosis Research Society-22 score between the patients with and without radiographic adverse events.

CONCLUSION

STF in Lenke 1C curves showed an acceptable risk of adverse radiographic events such as CD, LD, DA, and trunk shift in long-term follow-up. We suggest that STF without fusion to the thoracolumbar/lumbar curve would be sufficient in treating AIS with Lenke 1C curve.

LEVEL OF EVIDENCE

Level III.

The Importance of Lumbar Curve Flexibility and Apical Vertebral Rotation for the Prediction of Spontaneous Lumbar Curve Correction in Selective Thoracic Fusion for Lenke Type 1 and 2 C Curves: Retrospective Cohort Study with a Mean Follow-Up of More than 10 years

STUDY DESIGN

Retrospective analysis of a prospectively collected data.

OBJECTIVE

Lumbar flexibility(LF) is generally defined with preoperative side bending films;it is not clear what percentage of LF predicts the spontaneous lumbar curve correction (SLCC) at long term follow up. Aim of this study was to find out cut-off value of preoperative LF,apical vertebra rotation(AVR) and apical vertebral translation(AVT);which may predict more than 50%SLCC.

METHODS

Patients with Lenke 1C&2C curves,treated with posterior STF,with a minimum 10 years follow up were included.The patients who had more than 50% SLCC(Group A) or less than 50% (Group B) were compared in terms of LF,AVR and AVT to understand a cut-off value of those parameters.Statistically, Receiver Operating Characteristic(ROC) test was used.

RESULTS

Fifty five AIS patients (54F, 1M) with mean age 14 (11-17) were included to study.Thoracic curve correction rate was 75%;lumbar curve correction rate was 59% at the latest follow up.Group A included 45(82%) patients at the latest follow up.Three patients (5%) showed coronal decompensation at early postop and 2 of them became compensated at f/up.ROC analyses showed 69% flexibility as the cut-off value for SLCC (P < .01).The difference between groups in terms of preop mean AVRs was significant (P = .029) (Group A = 1.9; Group B = 2.4).

CONCLUSION

In Lenke 1C&2C curves,whenever LF on the preoperative bending x-ray is greater than 70% (P < .01)and AVR is equal or less than grade 2,STF provides satisfactory clinical and radiological SLCC with more than mean 10 years f/up.This flexibility rate and apical vertebral rotation can be helpful in decision making for successful STF.

Combination of Side-Bending and Traction Radiographs Do Not Influence Selection of Fusion Levels Compared to Either One Alone in Adolescent Idiopathic Scoliosis

STUDY DESIGN

A retrospective study.

OBJECTIVES

Curve flexibility in patients with adolescent idiopathic scoliosis (AIS) can be evaluated using different techniques. This study aimed to determine whether the combination of side-bending (SB) and traction (TX) radiographs influences preoperative planning for AIS than either radiograph alone.

METHODS

Thirty-two spine surgeons were asked to review 30 AIS Lenke type 1 cases and select an upper instrumented vertebra (UIV) and lower instrumented vertebra (LIV) for the posterior spinal instrumentation of each case. Each rater reviewed the cases 3 times in each round. The raters were provided with the full-length posteroanterior (PA) and lateral standing and SB radiographs for round 1; PA, lateral, and TX radiographs for round 2; and PA, lateral, SB, and TX radiographs for round 3. Intra- and inter-rater reliabilities were evaluated using Kappa statistics.

RESULTS

The intra-rater reliability for UIV and LIV was 0.657 and 0.612 between rounds 1 and 2, 0.634 and 0.692 between rounds 1 and 3, and 0.659 and 0.638 between rounds 2 and 3, respectively, which indicated substantial agreement between rounds. The inter-rater kappa reliabilities for UIV and LIV selection were 0.103 and 0.412 for round 1, 0.121 and 0.380 for round 2, and 0.125 and 0.368 for round 3, indicating slight to moderate agreement between raters.

CONCLUSIONS

Whether raters used either SB or TX radiography, or both in addition to PA and lateral standing radiographs, did not influence the decision making for UIV or LIV of AIS Lenke type 1 surgery.

Lumbar Adding-on of the Thoracic Spine After Selective Fusion in Adolescent Idiopathic Scoliosis Lenke Types 1 and 2 Patients: A Critical Appraisal

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

This study aimed to identify risk factors that predict lumbar curve adding-on in patients who had selective thoracic fusion.

SUMMARY OF BACKGROUND DATA

Selective thoracic fusion offers deformity correction of Lenke 1 and 2 thoracic curves and maintains lumbar range of movement. However, some patients may develop postoperative lumbar adding-on.

METHODS

This study included patients 18 years or younger that underwent spinal instrumentation for Lenke 1 and 2 curves.

RESULTS

A total of 161 patients were included (147 females, 14 males). The mean age was 14.0 ± 2.1 years: 103 patients were Lenke 1, and 58 patients were Lenke 2 curves. Ninety-seven patients underwent posterior approach surgery, whereas 64 via anterior approach. In the posterior approach group, 79(81.4%) patients underwent selective fusion. Ten patients (6.2%) had lumbar curve adding-on, with nine females and one male. There were seven Lenke 1 and three Lenke 2 patients. All 10 patients were lumbar modifier (a), with 5 hypokyphotic patients. Selective fusion was done in nine patients. Lumbar adding-on was seen most commonly between 6 months to 1 year postoperative period (five patients). Two patients had adding-on because of incorrect distal fusion level, six were due to 1A-R curve, one due to the inadvertent fusion from the excessive long rod at the subjacent level. In multivariate analysis, hypokyphotic patients were at higher risk of lumbar adding-on (odds ratio = 9.2). Patients with Risser classification 0, 1, 2, 3 were also at higher risk of lumbar adding-on (odds ratio =6.1).

CONCLUSION

The incidence of lumbar curve adding-on was 6.2%. Patients who were hypokyphotic and skeletally immature are nine times and six times more likely to have lumbar adding-on, respectively. This article examines adding-on in patients who had either anterior or posterior approach scoliosis surgeries, with follow-up stretching up to 10 years. This offers the rare opportunity to examine the natural history of the adding-on phenomenon.Level of Evidence: 3.

Long-term Outcome of Selective Thoracic Fusion Using Rod Derotation and Direct Vertebral Rotation in the Treatment of Thoracic Adolescent Idiopathic Scoliosis: More Than 10-Year Follow-up Data

STUDY DESIGN

This was a retrospective comparative study.

OBJECTIVE

To evaluate long-term outcomes of selective thoracic fusion (STF) using both rod derotation (RD) and direct vertebral rotation (DVR) with pedicle screw instrumentation (PSI) in the treatment of thoracic adolescent idiopathic scoliosis (AIS) with a minimum 10-year follow-up.

SUMMARY OF BACKGROUND DATA

Postoperative compensation and maintenance of the unfused lumbar curve after STF is very important factor for the satisfactory results in the treatment of thoracic AIS.

PATIENTS AND METHODS

Sixty-five patients with thoracic AIS treated with STF from the neutral vertebra (NV) to NV or NV-1 with RD and DVR were retrospectively analyzed with a minimum 10-year follow-up. Patients were divided into 2 groups: satisfactory (n=52) and unsatisfactory groups (n=13). Unsatisfactory results were defined as an adding-on, a lowest instrumented vertebra (LIV) tilt of >10 degrees, or coronal balance >15 mm.

RESULTS

No significant differences were observed in the main thoracic curve between the satisfactory and unsatisfactory groups postoperatively (P=0.218) and at the last follow-up (P=0.636). Significant improvements of LIV tilt and disk angle were observed in both groups, but these improvements deteriorated during the follow-up period in the unsatisfactory group. Significant differences of apical vertebra (AV) and end vertebra (EV) were observed postoperatively (AV: P=0.001, EV: P=0.001) and at the last follow-up (AV: P<0.000, EV: P<0.000) between the 2 groups.

CONCLUSIONS

STF using RD and DVR can achieve satisfactory deformity correction for thoracic AIS with satisfactory compensatory lumbar curve that was maintained over long-term follow-up. Progression of unfused lumbar curve closely related with LIV tilt and disk angle showing insufficient DVR. Therefore, STF with sufficient DVR required to achieve satisfactory deformity correction and prevent a distal adding-on phenomenon in the treatment of thoracic AIS.

Frontal and sagittal imbalance in patients with adolescent idiopathic deformity

The human spinal column underwent many significant changes over the 4.5 million years of our ancestral bipedalism. The main change, however, came with acquiring multiple curvatures in the sagittal plane. This alteration seems to have exposed a weakness in our body's keystone and made us susceptible to thus far unbeknown problems of the spine because it has been noted that idiopathic scoliosis has not been observed in other primates. Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine causing an imbalance of the trunk as it increases in magnitude. A scoliotic curve comprises three components, the coronal, sagittal, and axial so that each curve can affect the global balance of the body differently. Patients with significant scoliotic deformities often find themselves at a biomechanical disadvantage when it comes to energy expenditure and keeping an upright stance. The pioneers of scoliosis research recognized the need for describing and quantifying deformity to better understand it, so they first translated clinical measurements to radiographs and built from there. The development of concepts like defining a curve by its end vertebrae and measuring its magnitude, assessing global spinal balance, describing the stable zone, and pinpointing the stable vertebra all followed suit. The importance of sagittal balance and restoring sagittal parameters during treatment was emphasized. In a quest to bring order to chaos, some tried to classify various scoliotic curve types. These classifications helped steer treatment decisions but were found lacking in many aspects. So far, a widely accepted three-dimensional classification of scoliosis still does not exist. This review aims to provide the reader with an overview of the development of balance and imbalance concepts in scoliosis.

Selective Thoracic Fusion for King-Moe Type II/Lenke 1C Curve in Adolescent Idiopathic Scoliosis: A Comprehensive Review of Major Concerns

INTRODUCTION

Controversies still exist in the surgical indications and outcomes of selective thoracic fusion (STF) for a primary thoracic curve with a compensatory large lumbar curve (King-Moe type II/Lenke 1C curve) in adolescent idiopathic scoliosis (AIS). Issues of the greatest concern regarding this curve type include curve criteria that indicate STF to prevent postoperative coronal decompensation and postoperative radiographic outcomes, including curve correction, coronal balance, and thoracolumbar kyphosis, after STF.

METHODS

This review comprehensively documents the issues raised in the literature regarding surgical indications and radiographic outcomes of STF for King-Moe type II/Lenke 1C curve in AIS.

RESULTS

Studies suggest that radiographic curve criteria indicating STF for this curve type include the preoperative dominance of the thoracic curve to the lumbar curve in the Cobb angle and the characteristics of the lumbar curve in magnitude and flexibility. Studies warn the need for a careful clinical evaluation of the thoracic and lumbar rotational prominences. Documented radiographic outcomes of importance include the postoperative behavior of the unfused lumbar curve, coronal or sagittal decompensation after STF, and factors associated with these issues. A comprehensive review of the literature suggests that the use of a segmental pedicle screw construct and better instrumented thoracic curve correction achieve better spontaneous lumbar curve correction. Although the causes of postoperative coronal decompensation remain multifactorial, preoperative coronal decompensation to the left and an inappropriate selection of the lowest instrumented vertebra are consistently reported to be the major causative factors.

CONCLUSIONS

STF has been validated in general for the treatment of King-Moe type II or Lenke 1C curve in AIS; however, controversies remain regarding the surgical indications and outcomes. Long-term impacts of residual lumbar curve, coronal decompensation, and mild thoracolumbar kyphosis on clinical outcomes after STF, along with optimal indications and strategy for STF, should further be assessed.

ROTATION ASSESSMENT IN ADOLESCENT IDIOPATHIC SCOLIOSIS WITH ROD DEROTATION

Objective:

Adolescent idiopathic scoliosis (AIS) is characterized by rotational and lateral deformity of the spine. The measurement of vertebral rotation is important for prognosis and treatment. Our objective was to evaluate whether the Nash-Moe method can be used to measure axial deformity correction with surgical treatment using the rod derotation maneuver at both the apex and extremities of the deformity in patients with AIS.

Methods:

Rotation was assessed using the Nash and Moe criteria, on preoperative and postoperative radiographs. We also evaluated the severity on the coronal plane using the Cobb method, ratio of correction achieved, screw density, and number of vertebrae involved in the instrumentation.

Results:

The Cobb method correction average was 54.8%. When we disregarded vertebrae that presented preoperative Nash-Moe grade 0, the average measurable correction was 54.5% in the first non-instrumented vertebra above, 69.2% in the first instrumented vertebra, 32.2% in the apical vertebra, 36.8% in the last instrumented vertebra, and 30% in the first non-instrumented vertebra below. In our study, 32.14% of the patients presented a measurable correction in the apical vertebra.

Conclusion:

On the axial plane, correction can be satisfactorily evaluated using the Nash-Moe method. Level of Evidence VI. Case Series.

Relationships Between the Axial Derotation of the Lower Instrumented Vertebra and Uninstrumented Lumbar Curve Correction: Radiographic Outcome in Lenke 1 Adolescent Idiopathic Scoliosis With a Minimum 2-Year Follow-up

BACKGROUND

Preoperative spinal parameters are used to guide the fusion levels in adolescent idiopathic scoliosis (AIS) spinal surgery. However, the impact of the factors modifiable by the surgeon in varying levels of preoperative patient-specific variables is not fully explored. The goal of this study was to identify the association between axial rotation correction of the lower instrumented vertebra (LIV) and spontaneous correction of the uninstrumented lumbar spine as a function of preoperative 3 dimensional (3D) curve characteristics in Lenke 1 AIS.

METHODS

Twenty-three Lenke1 AIS with a minimum 2-year follow-up were included. All patients had biplanar spinal x-rays and 3D reconstructions at preoperative, first erect, and 2-year follow-up visits. Five patient factors were measured preoperatively: kyphosis and lumbar modifiers, and thoracic to lumbar curve rotation, translation, and frontal deformity angle ratios. One surgical factor, percentage of LIV rotation correction, was determined from the preoperative and first erect 3D models. A factorial design analysis was implemented to determine the impact of surgical and patient factors, both separately and in combination, on 2-year radiographic outcomes of spontaneous correction of the uninstrumented spine.

RESULTS

Spontaneous lumbar Cobb and lumbar apical rotation correction were predicted significantly by patient and surgical factors, P<0.05. Lumbar modifier, percentage correction of LIV rotation, the interaction between LIV rotation correction and lumbar modifier, and the interaction between LIV rotation correction and thoracic to lumbar apical vertebrae translation ratio correlated significantly to 2-year outcomes of spontaneous lumbar Cobb correction, P<0.05. Lumbar modifier and the interaction between the Cobb ratio and the percentage of the LIV rotation correction correlated significantly to 2-year outcomes of lumbar apical rotation correction, P<0.05.

CONCLUSION

The relationship between LIV rotation correction and spontaneous lumbar curve correction after selective thoracic fusion varied based on the patient's 3D preoperative curve characteristics. Patients with lumbar modifier C and apical vertebrae translation ratios >1.5 showed improved lumbar Cobb correction in 2-years when 50% or more LIV rotation correction was achieved surgically.

Current concepts in the surgical management of adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is a complex 3D deformity of the spine. Its prevalence is between 2% and 3% in the general population, with almost 10% of patients requiring some form of treatment and up to 0.1% undergoing surgery. The cosmetic aspect of the deformity is the biggest concern to the patient and is often accompanied by psychosocial distress. In addition, severe curves can cause cardiopulmonary distress. With proven benefits from surgery, the aims of treatment are to improve the cosmetic and functional outcomes. Obtaining correction in the coronal plane is not the only important endpoint anymore. With better understanding of spinal biomechanics and the long-term effects of multiplanar imbalance, we now know that sagittal balance is equally, if not more, important. Better correction of deformities has also been facilitated by an improvement in the design of implants and a better understanding of metallurgy. Understanding the unique character of each deformity is important. In addition, using the most appropriate implant and applying all the principles of correction in a bespoke manner is important to achieve optimum correction.

In this article, we review the current concepts in AIS surgery.

Cite this article: Bone Joint J 2018;100-B:415–24.

Five major controversial issues about fusion level selection in corrective surgery for adolescent idiopathic scoliosis: a narrative review

BACKGROUND CONTEXT

Shoulder imbalance, coronal decompensation, and adding-on phenomenon following corrective surgery in patients with adolescent idiopathic scoliosis are known to be related to the fusion level selected. Although many studies have assessed the appropriate selection of the proximal and distal fusion level, no definite conclusions have been drawn thus far.

PURPOSE

We aimed to assess the problems with fusion level selection for corrective surgery in patients with adolescent idiopathic scoliosis, and to enhance understanding about these problems.

STUDY DESIGN

This study is a narrative review.

METHODS

We conducted a literature search of fusion level selection in corrective surgery for adolescent idiopathic scoliosis. Accordingly, we selected and reviewed five debatable topics related to fusion level selection: (1) selective thoracic fusion; (2) selective thoracolumbar-lumbar (TL-L) fusion; (3) adding-on phenomenon; (4) distal fusion level selection for major TL-L curves; and (5) proximal fusion level selection and shoulder imbalance.

RESULTS

Selective fusion can be chosen in specific curve types, although there is a risk of coronal decompensation or adding-on phenomenon. Generally, wider indications for selective fusions are usually associated with more frequent complications. Despite the determination of several indications for selective fusion to avoid such complications, no clear guidelines have been established. Although authors have suggested various criteria to prevent the adding-on phenomenon, no consensus has been reached on the appropriate selection of lower instrumented vertebra. The fusion level selection for major TL-L curves primarily focuses on whether distal fusion can terminate at L3, a topic that remains unclear. Furthermore, because of the presence of several related factors and complications, proximal level selection and shoulder imbalance has been constantly debated and remains controversial from its etiology to its prevention.

CONCLUSIONS

Although several difficult problems in the diagnosis and treatment of adolescent idiopathic scoliosis have been resolved by understanding its mechanism and via technical advancement, no definite guideline for fusion level selection has been established. A review of five major controversial issues about fusion level selection could provide better understanding of adolescent idiopathic scoliosis. We believe that a thorough validation study of the abovementioned controversial issues can help address them.

Maintenance of spontaneous lumbar curve correction following thoracic fusion of main thoracic curves in adolescent idiopathic scoliosis

AIMS

The aims of our study were to provide long-term information on the behaviour of the thoracolumbar/lumbar (TL/L) curve after thoracic anterior correction and fusion (ASF) and to determine the impact of ASF on pulmonary function.

PATIENTS AND METHODS

A total of 41 patients (four males, 37 females) with main thoracic (MT) adolescent idiopathic scoliosis (AIS) treated with ASF were included. Mean age at surgery was 15.2 years (11 to 27). Mean follow-up period was 13.5 years (10 to 18).

RESULTS

For the TL/L curve, the mean curve flexibility evaluated with supine pre-operative bending radiographs was 78.6% (standard deviation 16.5%), with no significant loss of correction observed. On comparing patients with an increase of the TL/L curve increase (> 4º, n = 9, 22%) to those without, significant differences were observed in the correction rate of the MT curve at the final follow-up (p = 0.011), correction loss of the MT curve (p = 0.003) and the proportion of patients who had semi-rigid instrumentation (p = 0.003). Pre-operative percentage predicted forced vital capacity (%FVC) was 80%, dropping to 72% at final follow-up (p < 0.001). The Scoliosis Research Society questionnaire score was not significantly different between patients with and without a TL/L curve increase (p = 0.606). Spontaneous lumbar curve correction (SLCC) was maintained up to 18 years following selective ASF in most patients and demonstrated significant correlation with maintenance of MT curve correction.

CONCLUSION

Maintenance of MT curve correction using rigid instrumentation provided stable SLCC over time. An observed 8% decrease in %FVC indicates that ASF should be reserved for patients with no or only mild pulmonary impairment. Cite this article: Bone Joint J 2016;98-B:997-1002.

The Surgical Overcorrection of Lenke Type 1 Deformities with Selective Fusion Segments: What Happens to the Coronal Balance?

PURPOSE

The aim of our study is to determine the alterations on coronal balance after overcorrection of Lenke type 1 curve, retrospectively.

METHODS

Datas of 34 patients (29 female, 5 male patients; mean age, 16.3±3.3 years; range, 13-24 years) surgically treated for scoliosis between 2004 and 2010 were reviewed, retrospectively. The adolescent idiopathic scoliosis patients with Lenke type 1 curve treated with only posterior pedicle screw and postoperative thoracic curves less than 10° by Cobb method on frontal plane were enrolled in this study. Mean follow-up period was 52.5±29.7 months.

RESULTS

The mean amount of the preoperative thoracic curves was measured as 41.2°±6.1° (range, 30°-56°). The mean amount of the early postoperative thoracic curves was measured as 6.5°±1.8° (range, 3°-9°). The mean amount of the thoracic curves was measured as 8.5°±4.6° (range, 3°-22°) during the last follow-up (p=0.01). The mean preoperative coronal balance was measured as 8.5mm(range, 1-30mm). The mean early postoperative coronal balance was measured as 3.5mm(range, 0-36 mm). The mean coronal balance was measured as 5.5mm(range, 0-38mm) during the last follow-up (p>0.05).

CONCLUSION

We suggest that Lenke type 1B and 1C should be carefully evaluated and the fusion levels should be accurately selected in order to maintain the correction of coronal balance. We suggest that selective fusion with overcorrection in Lenke type 1A are applied to curves that can be corrected lumbar curve at the preoperative bending radiograph and curves that not have coronal decompensation and >10° distal junctional kyphosis, preoperatively.

Assessment of spontaneous correction of lumbar curve after fusion of the main thoracic in Lenke 1 adolescent idiopathic scoliosis

Objective

To evaluate the clinical and radiographic response of the lumbar curve after fusion of the main thoracic, in patients with adolescent idiopathic scoliosis of Lenke type 1.

Methods

Forty-two patients with Lenke 1 adolescent idiopathic scoliosis who underwent operations via the posterior route with pedicle screws were prospectively evaluated. Clinical measurements (size of the hump and translation of the trunk in the coronal plane, by means of a plumb line) and radiographic measurements (Cobb angle, distal level of arthrodesis, translation of the lumbar apical vertebral and Risser) were made. The evaluations were performed preoperatively, immediately postoperatively and two years after surgery.

Results

The mean Cobb angle of the main thoracic curve was found to have been corrected by 68.9% and the lumbar curve by 57.1%. Eighty percent of the patients presented improved coronal trunk balance two years after surgery. In four patients, worsening of the plumb line measurements was observed, but there was no need for surgical intervention. Less satisfactory results were observed in patients with lumbar modifier B.

Conclusions

In Lenke 1 patients, fusion of the thoracic curve alone provided spontaneous correction of the lumbar curve and led to trunk balance. Less satisfactory results were observed in curves with lumbar modifier B, and this may be related to overcorrection of the main thoracic curve.

Sagittal Alignment Two Years After Selective and Nonselective Thoracic Fusion for Lenke 1C Adolescent Idiopathic Scoliosis

STUDY DESIGN/SETTING

Matched cohort.

OBJECTIVE

To evaluate thoracic and thoracolumbar sagittal Cobb angles in patients undergoing either selective thoracic fusion (STF) or nonselective thoracic fusion (NSTF) for Lenke 1C adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

The Lenke classification is used to guide fusion levels in AIS. For some curve types, including 1C, there is a disparity in practice regarding whether the thoracolumbar/lumbar curve should be included in the arthrodesis. The impact of performing an NSTF on sagittal parameters has not been adequately evaluated.

METHODS

A multicenter database of AIS was queried for patients with right-sided 1C curves treated with posterior correction and fusion. A matched cohort for each group was created based on age, gender, preoperative Cobb angles, and Scoliosis Research Society-22R domain scores. Independent t tests for continuous variables and Fisher exact test for categorical variables were used to compare the STF and NSTF groups.

RESULTS

Thirty-eight patients who underwent NSTF were matched to 38 patients in the STF. An average of 8.0 levels were fused in the STF group and 11.6 in the NSTF group (p < .001). Preoperative and radiographic variables were similar between the two groups. Postoperatively, there was a statistically significant difference between the STF and NSTF sagittal Cobb in the thoracic spine, 26.9° and 21.7° (p = .013). The greatest difference was in the thoracolumbar sagittal Cobb, which increased to 4.3° kyphosis in the STF group and decreased to 9° of lordosis in the NSTF group (p < .001). Residual thoracolumbar/lumbar scoliosis was 25.5° in the STF group and 14.5° in the NSTF group (p < .001).

CONCLUSIONS

STF in 1C curves preserves lumbar motion segments but may be associated with an increase in thoracic and thoracolumbar kyphosis compared to NSTF. As expected, residual thoracolumbar/lumbar scoliosis was less in the NSTF group compared to the STF group. Although the long-term implications of these changes are unknown, consideration of sagittal balance is critical. Following these patients in the medium and long term will provide important information to guide fusion levels.

LEVEL OF EVIDENCE

II.

Selective Thoracic Fusion Provides Similar Health-Related Quality of Life but Can Cause More Lumbar Disc and Facet Joint Degeneration: A Comparison of Adolescent Idiopathic Scoliosis Patients With Normal Population 10 Years After Surgery

OBJECTIVES

To evaluate the long-term behavior of the lumbar curve in patients with adolescent idiopathic scoliosis treated with selective thoracic fusion and to assess the clinical and radiologic outcomes in this fusion group compared with an age- and gender-matched group.

SUMMARY OF BACKGROUND DATA

Selective thoracic fusion for the treatment of adolescent idiopathic scoliosis (AIS) preserves lumbar motion segments but leaves a residual deformity. By avoiding fusion of the lumbar spine, a greater mobility may be preserved, which may be an advantage in long-term follow-up in terms of degenerative changes in unfused segments.

METHODS

Group A included 25 AIS patients with mean a age of 23.8 years and a mean 11.4 years of follow-up. Group B included 30 age- and gender-matched subjects without any deformity. Preoperative, postoperative, and follow-up radiographs were reviewed. All patients had MRIs taken at the final follow-up in order to evaluate disc degeneration (DD) and facet joint degeneration (FJD) at the unfused lumbar spine. Clinical evaluation was done by using Scoliosis Research Society-22R, Oswestry Disability Index, and numerical rating scale.

RESULTS

Sagittal and coronal balance and lowest instrumented vertebra disc angulation were stable over time. Mean grading of lumbar DD was 2.16 (2-4) in Group A and 1.86 (1-3) in Group B. Lumbar FJDs were 2.05 (1-4) in Group A and 1.60 (1-3) in Group B. There was significant difference between the two groups for DD except for the L4-L5 level (p = .26). FJD was significantly higher in the L1-L2 and L2-L3 levels (L1-L2, p = .002, L2-L3, p = .002) but not for the other levels. Outcome scores were similar without significant differences between the two groups (p > .05).

CONCLUSION

Selective thoracic fusion provides satisfactory outcomes at more than 10 years of follow-up. Our study demonstrated a moderate increase in the rate of disc degeneration in the unfused segments. Facet joint degeneration was significant at the upper two levels adjacent to the lowest instrumented vertebra.

Selective versus nonselective thoracic fusion in Lenke 1C curves: a meta-analysis of baseline characteristics and postoperative outcomes

OBJECT

Lenke 1C curves are challenging to manage surgically due to the structural thoracic deformity and nonstructural lumbar curve. Selective thoracic fusion (STF) is considered the standard of care because it preserves motion of the lumbar segment, yet nonselective STF (NSTF) remains prevalent. This study aims to identify baseline patient characteristics that drive treatment and to compare postoperative outcomes for both procedures.

METHODS

Studies that compared baseline and postoperative demographic data, health-related quality of life (HRQL) questionnaires, and radiographic parameters of patients with Lenke 1C curves undergoing STF or NSTF were identified for meta-analysis. The effect measure is expressed as a mean difference (MD) with 95% CI. A positive MD signifies a greater STF value, or a mean increase within the group.

RESULTS

One prospective and 6 retrospective case-control studies with sample size of 488 patients (344 STF and 144 NSTF) were identified. Baseline age, sex, and HRQLs were equivalent, except for better scores in the STF group for the Scoliosis Appearance Questionnaire (SAQ): Unrelated to Deformity item (3.47 vs 3.88, p = 0.01) and the Spine Research Society questionnaire, Item 22: Pain (4.13 vs 3.92, p = 0.04). Radiographic findings were significantly worse in NSTF, as measured by the thoracolumbar/lumbar (TL/L) Cobb angle (MD: -4.29°, p < 0.01) and TL/L apical vertebral translation (AVT) (MD: -6.08, p < 0.01). Radiographic findings significantly improved in STF, as measured in the main thoracic (MT) Cobb angle (MD: -27.78°, p < 0.01), TL/L Cobb angle (MD: -16.24°, p < 0.01), MT:TL/L Cobb ratio (MD: -0.21, p < 0.01), coronal balance (MD: 0.47, p = 0.02), and thoracic kyphosis (MD: 7.87°, p < 0.01); and in NSTF in proximal thoracic (PT) Cobb angle (24° vs 14.1°, p < 0.01), MT Cobb angle (53.5° vs 20.5°, p < 0.01), and TL/L Cobb angle (41.6° vs 16.6°, p < 0.01). Postoperative TL/L Cobb angle (23.1° vs 16.6°, p < 0.01) was significantly higher in STF; but PT Cobb angle, MT Cobb angle, and MT:TL/L Cobb ratio are equivalent.

CONCLUSIONS

Patients with larger lumbar compensatory curves displaying a larger degree of coronal translation, as measured by the TL/L AVT, are more likely to undergo an NSTF. Contrary to established guidelines, larger MT curve magnitudes and MT:TL/L Cobb angle ratios have not been found to influence the decision to pursue a selective thoracic fusion. Although overall both STF and NSTF groups are found to have effective postoperative coronal balance, the STF group has only modest improvements in the lumbar curve position as determined by a relatively unchanged TL/L AVT. Furthermore, surgeons may prefer NSTF in patients who may have a worse overall perception of their spinal deformity as measured by HRQL measures of pain and desire for appearance change.

Evaluation of idiopathic scoliosis by anterior and posterior arthrodesis

<sec><title>OBJECTIVE:</title><p> To evaluate comparatively surgical treatment of adolescent idiopathic scoliosis type 5CN by anterior and posterior approach.</p></sec><sec><title>METHODS:</title><p> The study consists of a comparative retrospective study of two groups of patients with the thoracolumbar spine arthrodesis technique by anterior and posterior approach. Twenty and two patients were sequentially selected, 11 operated by anterior approach - called Group I - and 11 by posterior approach - Group II. Anamnesis and physical examination were performed, as well as length of hospital stay and ICU stay, degree of correction, comorbidities and pre and postoperative radiographic images data were gathered.</p></sec><sec><title>RESULTS:</title><p> The mean age was 13.7 years in Group I and 14 years in Group II. The average hospital stay was 5.81 days for Group I and 5 for Group II. The average ICU stay was 2.81 and 2 days, respectively. Considering the operated levels, Group I presented an average of 4.81 vertebrae (4-6 levels), and Group II presented an average of 6.36 vertebrae (5-11 levels). Complications did not show statistically significant difference.</p></sec><sec><title>CONCLUSION:</title><p> Despite the limited number of patients in groups, it was demonstrated that the posterior approach reduces the number of days of hospitalization and ICU stay. However, it was found increased levels included in the arthrodesis.</p></sec>

Could structural and noncompensatory Lenke 3 and 4C lumbar curves be nonstructural and compensatory? Lenke 1, 2, 3, and 4 curve types were similar and could be considered collectively as a single indication for selective thoracic fusion

STUDY DESIGN

Retrospective radiographical review.

OBJECTIVE

To demonstrate that the structural and noncompensatory Lenke 3 and 4C lumbar curves could be nonstructural and compensatory.

SUMMARY OF BACKGROUND DATA

Historically, Lenke 3 and 4C curves were not recommended for selective thoracic fusion (STF) because the lumbar curve was considered structural and noncompensatory. However, consecutive series of Lenke 3 and 4C curves suggest successful treatment with STF.

METHODS

Between 2001 and 2004, 2005 and 2008, and 2010 and 2012, 3 consecutive series of 108, 134, and 78 surgically treated Lenke 1, 2, 3, and 4C curves were reviewed, respectively. The coronal curve criteria for the curves treated with STF during each period were lumbar side bending Cobb angle less than 25° and meeting the Lenke ratio criteria, lumbar side bending Cobb angle 35° or less, and lumbar side bending Cobb angle 45° or less, respectively. The sagittal curve criteria for STF during each period was absence of junctional thoracolumbar kyphosis 20° or more between T10 and L2. The technique used for STF was the Guan-Din method. Radiographs of all the curves treated with STF were analyzed before and after surgery.

RESULTS

Optimal instrumented thoracic and compensatory lumbar correction was obtained for all Lenke 1, 2, 3, and 4C curves treated with STF in each period. As the coronal criteria for STF were broadened, the extent of feasibility of STF was expanded and the rate of STF increased. Although Cobb angle, apical vertebral translation, and apical vertebral rotation magnitudes of Lenke 3 and 4C curves were larger and more severe than those of Lenke 1 and 2C curves, optimal compensatory correction could still be obtained for Lenke 3 and 4C curves.

CONCLUSION

The structural and noncompensatory Lenke 3 and 4C lumbar curves were proven to be nonstructural and compensatory. Lenke 1, 2, 3, and 4C curves have similar natures and similar responses to the same technique (Guan-Din method) used for STF and could be considered collectively as a single indication for STF. The extent of feasibility of STF could be expanded from Lenke 1 and 2 curves to Lenke 1, 2, 3, and 4 curves.

LEVEL OF EVIDENCE

2.

Risk Factors for Coronal Decompensation After Posterior Spinal Instrumentation and Fusion in Adolescent Idiopathic Scoliosis

STUDY DESIGN

Retrospective review of multicenter data set with adolescent idiopathic scoliosis (AIS) patients with at least 2 years of follow-up after posterior spinal instrumentation and fusion (PSIF).

OBJECTIVES

The purpose of this study is to investigate risk factors for coronal decompensation 2 years after PSIF for AIS.

SUMMARY OF BACKGROUND DATA

Coronal decompensation is a potential complication of spinal instrumentation for AIS. This can result in problems requiring revision surgery.

METHODS

Demographic, clinical, and radiographic measures were reviewed on 890 identified patients. Coronal decompensation was defined as a change farther away from midline from 6 weeks postoperatively to 2 years in any one of the following radiographic parameters: change in coronal balance >2 cm; change in coronal position of the lowest instrumented vertebra (LIV) >2 cm; change in thoracic trunk shift >2 cm; or change in LIV tilt angle >10°. Patients with decompensation were compared to those without. The relationship between the LIV and lowest end vertebra (LEV) was examined as an independent variable.

RESULTS

Two years postoperation, 6.4% (57/890) of patients exhibited coronal decompensation. Multivariate regression revealed that decompensated patients were twice as likely to be male, have lower preoperative Risser score, and lower percentage major curve correction. The relationship between the LIV and LEV as well as quality of life surveys were not significantly different between decompensated and nondecompensated patients at 2 years.

CONCLUSIONS

Two years after PSIF, 6.4% of patients with AIS exhibit radiographic coronal decompensation. Although this study did not demonstrate a significant association between the relationship of LIV and LEV and decompensation 2 years postoperation, results of this study indicate that skeletal immaturity, male gender, and less correction of the major curve may be related to higher rates of coronal decompensation.

Guan-Din method: a novel surgical technique for selective thoracic fusion to maximize the rate of selective thoracic fusion and compensatory correction

STUDY DESIGN

Retrospective radiographical review.

OBJECTIVE

To evaluate the outcome of selective thoracic fusion (STF) by using the Guan-Din method for the treatment of major thoracic compensatory lumbar (MTCL) curves.

SUMMARY OF BACKGROUND DATA

Performing STF for MTCL curves is to minimize the loss of lumbar motion and the risk of lumbar degeneration or pain. Surgical treatment of MTCL curves aims to maximize the rate of STF for MTCL curves while optimizing instrumental thoracic and compensatory lumbar correction. The Guan-Din method has been demonstrated to be able to enhance the lumbar curve's capacity for spontaneous correction and broaden the current curve criteria of MTCL curves for STF.

METHODS

Between 2004 and 2010, 510 consecutive surgically treated MTCL curves were reviewed. Of these MTCL curves, who met the criteria of lumbar side bending Cobb 35° or less and without global thoracic hyperkyphosis and/or thoracolumbar kyphosis (T10-L2 ≤20°), were treated with STF using the Guan-Din method. Radiographs were analyzed before surgery, immediately after surgery, and at the most recent follow-up (range, 2-8 yr).

RESULTS

Curve types of 510 MTCL curves according to Lenke system were as follows: 1A (n = 91), 2A (n = 74), 3A (n = 6), 4A (n = 2), 1B (n = 93), 2B (n = 34), 3B (n = 8), 4B (n = 5), 1C (n = 84), 2C (n = 26), 3C (n = 72), and 4C (n = 15). Of the 510 MTCL curves, 458 (90%) curves were treated with STF. A mean 73% thoracic correction and 63% lumbar correction was obtained at the most recent follow-up. Of the 197 surgically treated MTCL curves with a lumbar C modifier, 148 (75%) curves that contained 57 Lenke 1C and 2C curves and 40 Lenke 3C and 4C curves that did not meet Lenke curve criteria for STF, were successfully treated with STF. A mean 67% thoracic correction and 57% lumbar correction was obtained at the most recent follow-up. The rate of STF and the magnitude of correction of MTCL curves in this study were significantly greater than those in all other reports. No significant change in global coronal and sagittal imbalance was observed.

CONCLUSION

The rate of STF and the compensatory correction of MTCL curves could be maximized by using the Guan-Din method as the method for STF.

LEVEL OF EVIDENCE

4.

Traction X-ray under general anesthesia helps to save motion segment in treatment of Lenke type 3C and 6C curves

BACKGROUND CONTEXT

In patients with structural lumbar curves, several studies have shown the advantages of stopping fusion at L3 and saving L4. However, fusing the L4 may still be deemed necessary in a significant number of patients with structural lumbar curves (ie, Lenke types 3 and 6) when fusion levels are selected by using traditional flexibility X-ray (TXR) methods such as supine side bends and traction.

PURPOSE

The aim of this retrospective study was to evaluate the effectiveness of the traction X-ray under general anesthesia (TrUGA) method in saving the L4 in patients with Lenke types 3C and 6C curves.

STUDY DESIGN

This was a retrospective clinical study.

PATIENT SAMPLE

Eighty-nine consecutive patients (77 females and 12 males) with adolescent idiopathic scoliosis Lenke types 3C (46 patients) and 6C (43 patients) curves and who underwent an instrumented posterior spinal fusion by a single surgeon were included. The selection of lower instrumented vertebrae (LIV) was done by using the central sacral vertical line (CSVL). LIV was defined as the uppermost vertebrae of the lumbar curve that was not intersected by CSVL on standing anteroposterior radiograph, but became parallel to the sacrum and was intersected by CSVL at the concave bending or TrUGA. The disc wedging under LIV should be parallel or near parallel and rotation of LIV should be corrected at least one to two (Nash-Moe) grades.

OUTCOME MEASURES

Radiological evaluation included preoperative standing AP, lateral and TXR, and intraoperative supine TrUGA, which was taken after the induction of anesthesia and before positioning the patient. LIV was determined by using TXR and TrUGA. Preoperative, postoperative with ≥2 year follow-up curve magnitudes, LIV tilt, and disc wedging below LIV and CSVL to T1 distance were all measured. A satisfactory radiographic outcome was determined to be the result if CSVL was within 2 cm of the center of T1, the LIV tilt angle was less than 10°, and any increase in thoracic and lumbar curve during follow-up was less than 5°. Clinical outcome was analyzed by using follow-up Scoliosis Research Society-22 (SRS-22) questionnaire and by the global outcome scores (GOS) for improvement and deterioration measured with a 15-point scale ranging from -7 (no improvement) to +7 (significant improvement).

RESULTS

The average follow-up period was 5.4 (range: 2 to 8) years. Average age at surgery was 15.5 (range: 13 to 19) years. Pedicle screw constructs were used in all patients. LIV was L3 in 85 patients, and L4 in the remaining 4 patients. Using the same selection criteria, L3 was LIV according to both the TXR and TrUGA films in 39 cases (44%) and fusion was stopped at L3. In 46 (52%) cases, TXR determined L4 to be the LIV, whereas in all those patients L3 was the LIV according to TrUGA and fusion was stopped at L3 in all. LIV was L4 according to both methods in four (4%) patients and fusion was stopped at L4. All patients had successful radiographic outcomes according to the criteria of CSVL to be within 2 cm of the center of T1, L3 tilt angle of less than 10°, and L3-L4 disc wedging to be less than 10° at the final follow-up. Average follow-up SRS-22 score was 4.3 (range: 3.3-5) and GOS was 6.1 (range: 3-7). None of the patients required additional surgery for decompensation or adding on, and there was no significant correction loss during follow-up.

CONCLUSION

TrUGA may be an alternative method for selection of fusion levels and may help to save L4 when compared with traditional radiograph methods in surgical treatment of Lenke types 3 and 6 curves.

Is decompensation preoperatively a risk in Lenke 1C curves?

STUDY DESIGN

A review of a multicenter, prospective registry of patients surgically treated for adolescent idiopathic scoliosis.

OBJECTIVE

To investigate preoperative and postoperative distribution of coronal decompensation in Lenke 1C curves and to determine whether a selective thoracic fusion (STF) affects the results of coronal decompensation.

SUMMARY OF BACKGROUND DATA

Numerous causes of postoperative coronal decompensation in Lenke 1C curves have been reported; however, there are few reports focusing on preoperative decompensation and its relation to postoperative decompensation in Lenke 1C curves.

METHODS

Patients with Lenke 1C prospectively collected from a multicenter study were analyzed. Preoperatively, patients were grouped as decompensated (C7-CSVL > 2 cm) or balanced (C7-CSVL within 2 cm, where CSVL is central sacral vertical line). Preoperative distribution and factors for postoperative coronal decompensation were investigated.

RESULTS

Seventy-one patients (53 STF, 18 nonselective fusions) were included. Preoperatively, coronal balance was skewed to the left (-17 ± 13 mm). Of the 21 STF decompensated to the left preoperatively, 12 (57%) remained to the left at 2 years. Postoperative thoracic correction was significantly better in those balanced postoperatively (57%) compared with those who remained decompensated (46%; P < 0.05). There were 32 STF patients who were balanced preoperatively, with 10 of these (31%) decompensated to the left at 2-year follow-up. This rate (31%) was significantly less than the group that was decompensated preoperatively (57%, P = 0.04). In the nonselective fusion group, 16 out of 18 patients (89%) were balanced at 2-year follow-up, independent of preoperative balance.

CONCLUSION

Patients with Lenke 1C tended to be decompensated to the left preoperatively. In those decompensated preoperatively who underwent a STF, the majority remained greater than 2 cm to the left at 2-year follow-up. Patients with both thoracic and lumbar curves fused had better coronal balance at 2 years than selectively treated patients. Although not a contraindication to performing a selective fusion, treating surgeons should be prepared for modest coronal decompensation in 40% of patients with Lenke 1C treated with selective fusion of the thoracic curve alone.

LEVEL OF EVIDENCE

3.

The lasting legacy of Paul Randall Harrington to pediatric spine surgery

Spinal arthrodesis was the first successful treatment for scoliosis, performed by Dr. Russell A. Hibbs in 1911 and later by Dr. Fred H. Albee for tuberculosis. In 1914, Dr. H.P.H. Galloway and Dr. Hibbs began using the method to treat neuromuscular scoliosis in patients with poliomyelitis. However, this treatment approach was plagued by loss of deformity correction over time and high pseudarthrosis rates. The turning point in the operative management of spinal deformities began in 1947 with Dr. Paul Randall Harrington when he started a decade-long process to revolutionize surgical treatment of spinal deformities culminating in the advent of the Harrington Rod, the first successful implantable spinal instrumentation system. During the epoch that he was in practice, Dr. Harrington's achievement influenced the technology and art of spine surgery for his contemporaries and the coming generations of spine surgeons. The purpose of this article is to review the life of Dr. Harrington, and how he has arguably come to be known as “Father of the Modern Treatment of Scoliosis.”

Segurança da fusão seletiva na escoliose idiopática e evolução pós-operatória

OBJETIVOS: Analisar as correções obtidas através da instrumentação segmentar seletiva torácica, utilizando parafusos pediculares, em pacientes portadores de escoliose idiopática com modificador lombar B ou C; verificar a segurança da técnica e a descompensação das curvas compensatórias não instrumentadas; observar a perda de correção das curvas instrumentadas e não instrumentadas com o tempo. MÉTODOS: Estudo retrospectivo de pacientes portadores de escoliose idiopática com curvas 1B, 1C, 2B e 2C submetidos a tratamento cirúrgico por via posterior utilizando parafusos pediculares. As variáveis analisadas foram: sexo, idade, níveis acometidos pela escoliose, níveis instrumentados, número de parafusos pediculares utilizados, classificação segundo Lenke, ângulos de Cobb pré-operatórios coronal e sagital (incluindo inclinações), ângulos de Cobb no pós-operatório imediato e tardio e perda da correção das curvas com o tempo. Foram submetidos 20 pacientes portadores de escoliose idiopática à tratamento cirúrgico seletivo de agosto/2004 a outubro/2007. Destes, 18 permanecem em acompanhamento e foram incluídos no trabalho porque satisfizeram os critérios de inclusão. RESULTADOS: A média do ângulo de Cobb no pré-operatório foi de 52,61º, no pós-operatório imediato foi de 17,89º e no pós-operatório tardio, 22,15º, com média de correção imediata de 34,72° e perda de correção média 4,26º em 39,78 meses. Obteve-se uma correção espontânea média imediata de 22,62° nas curvas compensatórias não instrumentadas e perda média de 2,72º dessa correção em 39,78 meses. Não ocorreram complicações neurológicas, infecciosas ou descompensações das curvas lombares. CONCLUSÃO: Todos os pacientes apresentaram melhora substancial em termos estéticos, clínicos e radiológicos. Ocorreram perdas parciais da correção com o tempo, porém sem culminarem em descompensação das curvas não instrumentadas. Este trabalho mostra indícios de eficácia e segurança do tratamento cirúrgico seletivo da escoliose idiopática utilizando-se parafusos pediculares a médio/longo prazo.

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

STUDY DESIGN

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

OBJECTIVE

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

SUMMARY OF BACKGROUND DATA

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

METHODS

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

RESULTS

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

CONCLUSION

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

Lumbar curve is stable after selective thoracic fusion for adolescent idiopathic scoliosis: a 20-year follow-up

STUDY DESIGN

A retrospective cohort study comparing long-term clinical and radiographical outcomes using selective thoracic instrumented fusion versus long instrumented fusion for the treatment of adolescent idiopathic scoliosis (AIS).

OBJECTIVE

To evaluate long-term behavior of the lumbar curve in patients with AIS treated with selective thoracic fusion and to assess clinical outcome measures in this patient population compared with those patients treated with fusion in the lumbar spine.

SUMMARY OF BACKGROUND DATA

Selective thoracic fusion for the treatment of AIS preserves motion segments, but leaves residual lumbar deformity. Long-term results of selective fusion using segmental fixation are limited.

METHODS

Nineteen patients with AIS treated with selective thoracic fusion and 9 patients treated with a long fusion returned at a mean 20 years (range, 14-24 years) postoperatively for radiographs, clinical evaluation, and outcome surveys (Short Form-12, Scoliosis Research Society-24, Spinal Appearance Questionnaire, Oswestry Disability Index, and visual analogue scale for pain and stiffness). Curve types were Lenke 1B, 1C, or 3C. All patients underwent posterior fusion with Texas Scottish Rite Hospital or Cotrel-Dubousset hook-rod instrumentation.

RESULTS

The selective thoracic fusion group had no significant progression in the lumbar curve magnitude and no worsening of L4 obliquity to the pelvis between initial postoperative and 20-year follow-up. Mean preoperative lumbar curve magnitude (mean, 44°; range, 32-64) corrected 43% on initial postoperative films versus 38% at latest follow-up. Mean L4 obliquity to the pelvis, trunk shift, sagittal balance, and coronal balance were stable over time. Outcome scores between the 2 groups were similar. Scores in long fusion group, when compared with the selective group, were higher for 2 Scoliosis Research Society domains: self-image after surgery (P = 0.005) and function after surgery (P = 0.0006).

CONCLUSION

Spinal balance and correction of the lumbar curve remain stable over time in selective thoracic fusion. Those with selective fusions have outcome measures comparable with those with long fusions.

Spontaneous lumbar curve correction in selective anterior instrumentation and fusion of idiopathic thoracic scoliosis of Lenke type C

BACKGROUND

Posterior pedicle screw instrumented correction and fusion have become the gold standard in the surgical treatment of thoracic scoliosis. However, in thoracic Lenke type C curves selective posterior fusion of the thoracic curve may lead to spinal imbalance. The aim of the study was to analyse the radiological results of selective anterior thoracic fusion using a standard open dual rod technique with special respect to spontaneous lumbar curve correction (SLCC).

METHODS

Twenty-eight patients (26 patients with Lenke 1C and 2 patients with Lenke 2C curves) with an average age of 15 years were surgically treated with an anterior dual rod system through a standard open double thoracotomy approach. Average clinical and radiological follow-up was 4 years (24-84 months).

RESULTS

Fusion was carried out mostly from end-to-end vertebra. The primary curve was corrected from 61.6° (average correction on reverse bending films 42.9 %) to 27.1° (56.0 % correction) with an average loss of correction of 2.2°. The secondary lumbar curve measured 47.7° preoperatively (40-56°, average correction on reverse bending films 66.2 %) and corrected spontaneously to 30.1° (36 % SLCC) and remained stable without any cases of deterioration or decompensation during follow-up. Lumbar apical vertebral translation increased minimally by an average of 4 mm directly, postoperatively, and returned to an average of preoperative values during follow-up. All but two curves remained as type C lumbar modifier at follow-up. Preoperatively, three patients showed a marked coronal imbalance of more than 3 cm (all left, average 4.0 cm); at follow-up, two patients were still out of balance by more than 3 cm (all to the left, average 3.4 cm). Preoperatively, a marked shoulder imbalance of more than 1.0 cm was found in 11 patients; this was corrected in all patients to <1.0 cm at follow-up. The apical vertebral rotation measured according to Perdriolle was corrected from 23.5° to 15.0° in the thoracic spine (36.2 % correction) with an average clinical reduction of the rib hump of 63.2 %. In the lumbar spine, there was no relevant radiological derotation; however, clinically, the lumbar hump corrected spontaneously by 44.3 %. Thoracic kyphosis measured 28.5° preoperatively and 32.3° at follow-up. All six patients with a preoperative hypokyphosis (<20°) of an average of 9.5° were successfully corrected to an average thoracic kyphosis of 23.8° at follow-up. There were no cases of junctional thoracolumbar kyphosis. There were neither reoperations nor implant failures with pseudarthrosis.

CONCLUSION

Selective anterior correction and fusion in primary thoracic curves with lumbar modifier type Lenke C resulted in a reliable and satisfactory SLCC. Advantages of anterior versus posterior techniques are the true segmental derotation with excellent rib hump correction and a superior restoration of thoracic kyphosis.

Postoperative spinal alignment remodeling in Lenke 1C scoliosis treated with selective thoracic fusion

BACKGROUND CONTEXT

Selective thoracic fusion may cause spinal imbalance in certain patients; how the spinal alignment changes over time after surgery is highly correlated with the final spinal balance.

PURPOSE

To investigate how spinal alignment changes over time after selective thoracic fusion and how spinal alignment remodeling affects spinal balance.

METHODS

All adolescent idiopathic scoliosis (AIS) cases surgically treated in our institution between 2002 and 2008 were reviewed. Inclusion criteria were as follows: Lenke 1C scoliosis patients treated with posterior pedicle screw-only constructs; the lowest instrumented vertebra (LIV) ended at L1 level or above; and 2-year radiographic follow-up. Standing anteroposterior and lateral digital radiographs from four different time points (preoperatively, immediately, 3 months, and 2 years postoperatively) were reviewed. In each standing anteroposterior radiograph, the center sacral vertical line (CSVL, the vertical line that bisects the proximal sacrum) was first drawn, and the translation (deviation from the CSVL) of some key vertebrae was measured, such as the LIV, LIV+1 (the first vertebra below LIV), LIV+2 (the second vertebra below LIV), LIV+3 (the third vertebra below LIV), lumbar apical vertebra (AV), thoracic AV, and T1. Additionally, the Cobb angles of the major thoracic and lumbar curves were measured at different time points, and the correction rates were calculated. Furthermore, clinical photographs of the patients from the back were taken preoperatively and postoperatively.

RESULTS

Of 278 AIS patients reviewed, 29 met the inclusion criteria. The continuous follow-up of our present study revealed an interesting phenomenon: postoperative spinal alignment remodeling. A hypothetical criterion was established to determine the onset of the phenomenon. By means of a series of analyses, the criterion was validated. The results of our present study showed that selective thoracic fusion tended to cause leftward spinal imbalance in these Lenke 1C AIS patients. Twenty of the 29 patients had leftward spinal imbalance immediately after surgery. Although some patients regained spinal balance through postoperative spinal alignment remodeling, 11 patients remained imbalanced at 2-year follow-up.

CONCLUSIONS

Selective thoracic fusion is prone to cause leftward spinal imbalance in Lenke 1C scoliosis patients. Postoperative spinal alignment remodeling can facilitate recovery of spinal balance in some patients. Postoperative spinal imbalance in Lenke 1C scoliosis patients could be prevented by selecting stable vertebra or the vertebrae above as LIV, checking the balance condition during surgery, or considering ratio criteria when selecting candidates for selective thoracic fusion.

Lowest instrumented vertebra selection in Lenke 3C and 6C scoliosis: what if we choose lumbar apical vertebra as distal fusion end?

PURPOSE

The aim of this study was to investigate whether or not post-op curve behaviour differs due to different choices of lowest instrumented vertebra (LIV) with reference to lumbar apical vertebra (LAV) in Lenke 3C and 6C scoliosis.

METHODS

We reviewed all the AIS cases surgically treated in our institution from 2002 through 2008. Inclusion criteria were as follows: (1) patients with Lenke 3C or 6C scoliosis who were treated with posterior pedicle screw-only constructs; (2) 2-year radiographic follow-up. All the included patients were categorized into three groups based on the relative position of LIV and LAV: Group A-the LIV was above the LAV; Group B-the LIV was at the LAV; Group C-the LIV was below the LAV. All the radiographic parameters were then compared among the groups. All image data were available in our picture archiving and communication systems. Standing anteroposterior (AP) and lateral digital radiographs were reviewed at four times (pre-op, post-op, 3-month and 2-year). In each standing AP radiograph, centre sacral vertical line (CSVL, the vertical line that bisects the proximal sacrum) was first drawn, followed by measuring T1-CSVL, LIV-CSVL, (LIV + 1)-CSVL, LAV-CSVL and thoracic AV-CSVL distance. In addition, the Cobb angles of major thoracic and lumbar curves were measured at the four times and the correction rates were then calculated.

RESULTS

Of the 278 patients reviewed, 40 met the inclusion criteria; 11 of these were included in Group A (LIV above LAV), another 11 in Group B (LIV at LAV) and the remaining 18 in Group C (LIV below LAV). At 2-year follow-up, the lumbar vertebrae such as LIV, LIV + 1 and LAV were all more deviated than before surgery in Group A (LIV above LAV), whereas in Group B and C (LIV at and below LAV) they were all less deviated than before surgery. No significant differences were found in thoracic or lumbar correction rate, global coronal balance and incidence rate of trunk shift among the three groups.

CONCLUSION

In conclusion, in Lenke 3C and 6C scoliosis, post-op lumbar curve behaviour differs due to different choices of LIV with reference to LAV, that is, the deviation of lumbar curve improves when the LIV is either at or below the LAV but deteriorates when the LIV is above the LAV. Although the greatest correction occurs when the LIV is below the LAV, choosing LAV as LIV can still be the optimal option in certain cases, since it can yield similar correction while preserving more lumbar mobility and growth potential.

Pedicle screw instrumentation in adolescent idiopathic scoliosis (AIS)

INTRODUCTION

Pedicle screw instrumentation in AIS has advantages of rigid fixation, improved deformity correction and a shorter fusion, but needs an exacting technique.

MATERIALS AND METHODS

The author has been using the K-wire method with intraoperative single PA and lateral radiographs, because it is safe, accurate and fast. Pedicle screws are inserted in every segment on the correction side (thoracic concave) and every 2-3 on the supportive side (thoracic convex). After an over-bent rod is inserted on the corrective side, the rod is rotated 90° counterclockwise. This maneuver corrects the coronal and sagittal curves. Then the vertebra is derotated by direct vertebral rotation (DVR) correcting the rotational deformity. The direction of DVR should be opposite to that of the vertebral rotation. A rigid rod has to be used to prevent the rod from straightening out during the rod derotation and DVR. The ideal classification of AIS should address all curve patterns, predicts accurate fusion extent and have good inter/intraobserver reliability. The Suk classification matches the ideal classification is simple and memorable, and has only four structural curve patterns; single thoracic, double thoracic, double major and thoracolumbar/lumbar. Each curve has two types, A and B. When using pedicle screws in thoracic AIS, curves are usually fused from upper neutral to lower neutral vertebra. Identification of the end vertebra and the neutral vertebra is important in deciding the fusion levels and the direction of DVR. In lumbar AIS, fusion is performed from upper neutral vertebra to L3 or L4 depending on its curve types.

CONCLUSIONS

Rod derotation and DVR using pedicle screw instrumentation give true three dimensional deformity correction in the treatment of AIS. Suk classification with these methods predicts exact fusion extent and is easy to understand and remember.

Extensive fusion for Lenke 3C and 6C scoliosis: a two year radiographic follow-up

PURPOSE

To investigate the correction effectiveness, incidence rate of distal adding on, and post-operative spinal balance in Lenke 3C and 6C AIS treated with extensive fusion using posterior pedicle screw-only constructs.

METHODS

We reviewed all AIS cases surgically treated in our institution between 2002 and 2008. The inclusion criteria were as follows: (1) Lenke 3C or 6C scoliosis patients who were treated with extensive fusion using posterior pedicle screw-only constructs; (2) minimum two year radiographic follow-up; (3) the lowest instrumented vertebra (LIV) ended at L2, L3 or L4 level. All image data were available in our picture archiving and communication systems (PACSs) , and all radiographic measurements were performed. Standing anteroposterior (AP) and lateral digital radiographs were reviewed at four different time points (pre-op, post-op, three months, and two years). In each standing AP radiograph, CSVL (center sacral vertical line, the vertical line bisecting the proximal sacrum) was first drawn, followed by measurement of the translation (deviation from the CSVL) of some key vertebrae, such as the lowest instrumented vertebra (LIV), LIV + 1 (the first vertebra below LIV), lumbar apical vertebra, thoracic apical vertebra and T1, enabling depiction of how translation of different parts of the spine changes over time. Additionally, the Cobb angles of major thoracic and lumbar curves were measured at the different time points and the correction rate was calculated.

RESULTS

Of the 278 patients reviewed, 25 met the inclusion criteria. Immediately after surgery, satisfactory corrections were achieved from the perspective of not only Cobb angle but also vertebral translation. And the corrections were well retained in the following two years. The incidence rate of distal adding-on was low in this group of patients. In the course of two years following surgery, only six patients had an increase of greater than 5 mm in LIV + 1 translation, and among which only two patients had greater than 10 mm. Regarding global balance, overall, it neither improved nor deteriorated after extensive fusion. Furthermore, trunk shift was found in only three patients at two year follow-up.

CONCLUSIONS

In Lenke 3C and 6C scoliosis, extensive fusion can produce satisfactory corrections from the perspectives of both Cobb angle and vertebral translation and rarely causes significant distal adding-on, global imbalance or trunk shift.

Selective thoracic fusion in adolescent idiopathic scoliosis: factors influencing the selection of the optimal lowest instrumented vertebra

STUDY DESIGN

Analysis of multicenter, prospectively collected data.

OBJECTIVE

To determine how selection of the lowest instrumented vertebra (LIV) relative to the stable vertebra (SV) and the end vertebra (EV) effects correction of the main thoracic curve, compensatory lumbar curve, and incidence of coronal decompensation after selective thoracic fusion.

SUMMARY OF BACKGROUND DATA

Traditionally, in Lenke type 1B and 1C curves, the LIV is selected as the SV; however, selecting the LIV continues to be controversial.

METHODS

Inclusion criteria were patients with adolescent idiopathic scoliosis (AIS) with Lenke type 1B, 1C, or 3C curves that had a selective thoracic fusion with the LIV from T11 to L1 (n=172). The patients were divided into three curve patterns on the basis of the relative position of SV and EV. Group SBE (stable below end) (n=93) had SV below EV, group SAE (stable at end) (n=66) had SV at the EV, and group EBS (end below stable) (n=13) has EV below SV. In addition, each group was divided into six subgroups based on the selected LIV: LIV above SV, at the SV, below SV, above EV, at the EV, and below EV. Each was compared for preoperative and 2-year postoperative radiographic parameters and clinical data.

RESULTS

In group SBE, the 2-year postoperative thoracic curve correction rate when the LIV was below the EV (64%+16%) was significantly greater than when the LIV was at the EV (54%+13%; P<0.001). The 2-year postoperative spontaneous lumbar curve correction (SLCC) rate similarly correlated with the LIV selection subgroups, 52%+20% and 43%+19%, respectively (P=0.03). In group SAE, the 2-year postoperative thoracic curve correction rate when the LIV was below the EV/SV (64%+14%) was significantly greater than when the LIV was at the EV/SV (52%+14%; P=0.004). The 2-year postoperative SLCC rate for group SAE similarly correlated with the LIV selection subgroup, 56%+16% and 38%+21%, respectively (P<0.01). In group EBS, the 2-year postoperative thoracic curve correction and SLCC rates were not significantly different among the LIV selection subgroups; however, the incidence of decompensation was 38%.

CONCLUSION

When performing a selective thoracic fusion of Lenke type 1B, 1C, and 3C AIS curves in which the SV was at/or below the EV, the greatest correction of the main thoracic and compensatory lumbar curves occurred when the LIV was at/or at least one level distal to the SV. This more distal LIV did not result in an increased rate of truncal imbalance.

Pedicle screw instrumentation for adolescent idiopathic scoliosis: the insertion technique, the fusion levels and direct vertebral rotation

The pedicle is a power nucleus of the vertebra and offers a secure grip of all 3 columns. Pedicle screw instrumentation has advantages of rigid fixation with improved three-dimensional (3D) correction and it is accepted as a reliable method with a high margin of safety. Accurate placement of the pedicle screws is important to reduce possible irreversible complications. Many methods of screw insertion have been reported. The author has been using the K-wire method coupled with the intraoperative single posteroanterior and lateral radiographs, which is the most safe, accurate and fast method. Identification of the curve patterns and determining the fusion levels are very important. The ideal classification of adolescent idiopathic scoliosis should address the all patterns, predict the extent of accurate fusion and have good inter/intraobserver reliability. My classification system matches with the ideal classification system, and it is simple and easy to learn; and my classification system has only 4 structural curve patterns and each curve has 2 types. Scoliosis is a 3D deformity; the coronal and sagittal curves can be corrected with rod rotation, and rotational deformity has to be corrected with direct vertebral rotation (DVR). Rod derotation and DVR are true methods of 3D deformity correction with shorter fusion and improved correction of both the fused and unfused curves, and this is accomplished using pedicle screw fixation. The direction of DVR is very important and it should be opposite to the direction of the rotational deformity of the vertebra. A rigid rod has to be used to prevent rod bend-out during the derotation and DVR.

Selective fusion for adolescent idiopathic scoliosis: a review of current operative strategy

Selective fusion of thoracic and thoracolumbar/lumbar curves in adolescent idiopathic scoliosis is a concept critically debated in the literature. While some surgeons strongly believe that a more rigid and straighter spine provides predictably excellent outcomes, some surgeons recommend a mobile and less straight spine. This topic is a crucial part of surgical treatment of idiopathic scoliosis, particularly in young patients who will deal with the stress of the fusion mass at the proximal and distal junctions over many years. This study will review the literature on various aspects of selective fusion.

Predicting the outcome of selective thoracic fusion in false double major lumbar "C" cases with five- to twenty-four-year follow-up

STUDY DESIGN

Retrospective radiographic and clinical study.

OBJECTIVE

To examine the long-term outcome of selective thoracic fusion (STF) performed for lumbar "C" modifier curves in adolescent idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

The efficacy of STF in lumbar "C" false double major curves is controversial. We examined the 5- to 24-year outcomes of patients with "C" lumbar curves who underwent STF at a single institution to determine which factors help predict successful outcome.

METHODS

Thirty-two patients (age, 14.8 ± 2.0 years) with a lumbar "C" modifier underwent primary STF and had minimum 5-year follow-up (mean, 6.8 years). All patients were fused distally to either T12 or L1. At latest follow-up, 18 were considered successful (group S), 2 required reoperation to accommodate worsening deformity (group R), and 12 were considered marginal outcomes (group M), as defined by >3 cm coronal imbalance (n = 5), >5 mm worsening of lumbar apical vertebra translation compared with preoperative (n = 4), >1 Nash-Moe grade worsening of lumbar apical vertebra rotation (n = 1), >10° thoracolumbar junction kyphosis which was at least 5° worse than preoperative (n = 5), and lumbar Cobb angle >5° worse than preoperative (n = 2). Clinical outcomes were determined by Scoliosis Research Society (SRS)-30 at final follow-up.

RESULTS

Of the multiple factors considered, 2-month postoperative standing lumbar sagittal alignment was most predictive for long-term outcome (P < 0.019 by Kruskal-Wallis ANOVA). Satisfactory outcomes had statistically significantly greater T12-S1 lordosis than those that were marginal (64.8° (group S) vs. 52.0° (group M); P = 0.014) or required reoperation (64.8° [group S] vs. 38.0° [group R]; P < 0.001). Traditionally considered variables such as apical vertebra rotation, apical vertebra translation, Cobb angle magnitudes, coronal and sagittal balance, and their respective thoracic-to-lumbar ratios were not independently significant.

CONCLUSION

Selective thoracic fusions performed for lumbar "C" modifier scoliotic deformities generally have excellent long-term radiographic and SRS-30 outcomes at 5- to 24-year follow-up. Care should be taken to ensure that overcorrection of the thoracic curve is not performed beyond the ability of the lumbar curve to compensate. Furthermore, consideration of selective thoracic fusion should not be ruled out simply because the patient may have a somewhat stiff lumbar curve based on side-bending radiographs.

FUNCTIONAL AND RADIOGRAPHIC COMPARISON OF ANTERIOR AND POSTERIOR INSTRUMENTATION FOR THE CORRECTION OF ADOLESCENT IDIOPATHIC SCOLIOSIS

Objective: This was a retrospective study to compare the anterior instrumentation (AI) and posterior instrumentation (PI) results among patients diagnosed with adolescent idiopathic scoliosis (Lenke type I) who were treated surgically. Methods: The results from 24 patients aged 11 to 18 years with Lenke type I idiopathic scoliosis who underwent surgery with AI (12 patients) or PI (12 patients) were compared. All the patients were operated by the same surgeon and were followed up for a minimum period of five years. The variables for comparison included: coronal and sagittal correction, distance from apical vertebra to midline, apical vertebral rotation, number of instrumented vertebrae and functional variables (by means of the SRS-22 questionnaire). The data obtained were analyzed using the SAS software, version 9. The two groups were compared using Student's t-test with a significance level of 5% (0.05). Results: The correction of the curve in the frontal plane was higher in the group of patients with the anterior approach, in the immediate (p=0.031) and late (p=0.043) postoperative periods, as was the apical vertebral rotation during the immediate (p=0.002) and late (p=0.019) evaluations. The number of instrumented vertebrae was 7.69 ± 1.38 in the AI group and 11.38 ± 2.92 in the PI group (p = 0.021). Functional assessment (SRS-22) did not show any significant difference (p > 0.05) between the groups. Conclusion: The patients who underwent scoliosis correction with AI presented greater correction in the frontal plane, greater derotation of apical vertebrae and a smaller number of fused vertebrae.

Thoracic adolescent idiopathic scoliosis: selection of fusion level

Selection of the appropriate fusion levels in thoracic adolescent idiopathic scoliosis has been traditionally a subject of debate among surgeons. Landmarks that have been suggested include the end vertebra, stable vertebra and neutral vertebra. Various results have been reported with multiple theories proposed to explain them. The clinical appearance of the patient, the type of the curve and its flexibility, the surgical technique and the instrumentation used all seem to play major roles in selecting the appropriate levels of fusion.

Determination of lowest instrumented vertebra by the location of apical vertebra in Lenke type 1 adolescent idiopathic scoliosis

We postulated that the lowest instrumented vertebra (LIV) can be determined based on the apical vertebra. Seventy-two Lenke type 1 patients (average age: 13.6 years) receiving posterior spinal fusion were randomised into two groups. In group A, the apical vertebra was used to determine the LIV and in group B the neutral vertebra was used. All patients had Cobb angles <90° and average follow-up was over three years. Posteroanterior and lateral standing radiographs were used to assess flexibility, Cobb angle and distance from the C7 line to the central sacral vertical line. Both methods produced statistically significant changes in Cobb angle, sagittal T5-T12 and plumb line deviation, and there were no significant differences between the two methods. More cases of imbalance occurred in group B (five) than group A (two). We conclude that the apical vertebra can be used to determine the LIV in patients with Lenke type 1 adolescent idiopathic scoliosis.

Posterior selective thoracic fusion in adolescent idiopathic scoliosis patients: a comparison of all pedicle screws versus hybrid instrumentation

OBJECTIVE

To analyze the influence of segmental pedicle screws versus hybrid instrumentation on the correction results in adolescent idiopathic scoliosis patients undergoing posterior selective thoracic fusion,

METHODS

By reviewing the medical records and roentgenograms of adolescent idiopathic scoliosis patients who underwent selective thoracic fusion from February 2000 to January 2007 in our hospital, the patients were divided into 2 groups according to different instrumentation fashions: Group A was hook-screw-rod (hybrid) internal fixation type, Group B was screw-rod (all pedicle screws) internal fixation type, and the screws were used in every segment on the concave side of the thoracic curve. The parameters of the scoliosis were measured and the correction results were analyzed,

RESULTS

Totally, 48 patients (7 males, 41 females) were included, with an average age of 14.4 years old and a mean follow-up time of 12.3 months. Thirty and 18 patients were assigned to group A and group B, respectively. The mean preoperative coronal Cobb angles of the thoracic curve were 48.8 degrees and 47.4 degrees, respectively. After surgery, they were corrected to 13.7 degrees and 6.8 degrees, respectively. At final follow-up, they were 17.0 degrees and 9.5 degrees, with an average correction rate of 64.6% and 79.0%, respectively, and the correction rate of group B was significantly higher than that of group A (P = 0.003). The mean preoperative coronal Cobb angles of the lumbar curve were 32.6 degrees and 35.2 degrees, respectively. After surgery, they were corrected to 8.6 degrees and 8.3 degrees, respectively. At final follow-up, they were 10.3 degrees and 11.1 degrees, with an average correction rate of 66.8% and 69.9%, respectively, and the correction rate of group B was significantly higher than that of group A (P = 0.003). The correction loss of the thoracic curve and lumbar curve in the 2 groups were 3.1 degrees and 1.8 degrees, 2.4 degrees and 2.4 degrees, respectively. No significant difference was noted (both P > 0.05). The decompensation rate at final follow-up in these 2 groups were 4% (1/25) and 7.1% (1/14) respectively, with no significant difference (P > 0.05).

CONCLUSIONS

Both all pedicle screws and hybrid instrumentation can offer good correction results of the thoracic curve and lumbar curve in posterior selective thoracic fusion in patients with adolescent idiopathic scoliosis. While with all pedicle screws, the correction results of the thoracic curve and lumbar curve are both better than those with hybrid instrumentation without increased decompensation rate.

The deformity-flexibility quotient predicts both patient satisfaction and surgeon preference in the treatment of Lenke 1B or 1C curves for adolescent idiopathic scoliosis

STUDY DESIGN

Analysis of patient and surgeon preference between selective and nonselective thoracic spinal fusions.

OBJECTIVE

The purpose of this study was: (1) to determine patient preference between a longer, straighter fusion versus a shorter fusion with a residual lumbar deformity, and (2) to determine surgeon preference based on a cross-sectional survey.

SUMMARY OF BACKGROUND DATA

In the surgical treatment of Lenke 1B and 1C curves, choosing between a selective thoracic fusion which may leave residual lumbar deformity versus a fusion into the lower lumbar spine which may improve correction at the expense of lumbar motion continues to be debated.

METHODS

The deformity-flexibility quotient (DFQ) was defined to quantify the 2 primary yet competing goals of adolescent idiopathic scoliosis surgery, and is calculated by dividing the residual coronal lumbar deformity by the number of unfused distal motion segments. Patient preference between a selective versus nonselective fusion was determined using a Spearman's Rho analysis to correlate radiographic data (including the DFQ) with Scoliosis Research Society-24 scores. Surgeon preference was determined using a cross-sectional survey of 12 experienced scoliosis surgeons.

RESULTS

One hundred fifty-five adolescent idiopathic scoliosis patients were included in the analysis. At 2-year postoperative, the number of distal unfused motion segments averaged 5.8 +/- 1.4 (range: 2-9) and the residual thoracolumbar/lumbar deformity averaged 20.1 degrees +/- 8.8 degrees (range: 1 degrees -43 degrees ). This resulted in an average DFQ of 3.6 +/- 1.9 (range: 0.2-12.3). A lower DFQ was found to significantly correlate with improved patient satisfaction scores (r = -0.16, P = 0.04). In the cross-sectional survey, a lower DFQ also predicted the surgeon preferred radiograph in greater than 70% of the pairings.

CONCLUSION

The DFQ quantifies the perceived trade off between residual deformity and spared motion segments. Two-year postoperative patient satisfaction, as measured by the Scoliosis Research Society-24 questionnaire, and surgeon preference, in terms of coronal radiographic outcome, correlated significantly with the DFQ.

Selective thoracic surgery in the Lenke type 1A: King III and King IV type curves

Pedicle screw fixation enables enhanced three-dimensional correction of spinal deformities and effectively shortens the distal fusion level. However, the choice of distal fusion level is still controversial in single thoracic idiopathic scoliosis with the lumbar compensatory curve not crossing the middle line (Lenke type 1 with modifier A or King type III and IV curves).The authors retrospectively analyzed 31 patients treated by segmental pedicular instrumentation alone, affected by a single thoracic adolescent idiopathic scoliosis with a compensatory lumbar curve not crossing the midline (Lenke 1A), with an average age of 16.3 years (range 10-22 years). The patients with regard to the King classification were also assessed. A statistical analysis was performed to determine whether the two groups (King III, King IV) presented differences concerning the level of the stable vertebra (SV), end vertebra (EV), and neutral vertebra (NV) and were also analyzed the results at follow-up regarding the relationships between the SV, EV, and lowest instrumented vertebra (LIV). The statistical analysis showed a significant difference between the two curve types. In the King III type curve the SV, EV, and NV appeared to be more proximal than those of the King IV type curve and the segments between the SV, EV, and NV appeared to be reduced in King III curves compared with King IV curves. At a follow-up of 3.2 years (range 2.2-5) the thoracic curve showed a correction of 58.4% (from 62.3 degrees to 26.6 degrees ) and compensatory lumbar curve an average spontaneous correction of 52.4% (from 38.1 degrees to 18.1 degrees ).The position of the LIV was shorter than the position of the SV in 30 patients (97%) with an average "salvage" of 2.1 (from 1 to 4) distal fusion levels. Four cases (13%), all affected by a King IV type curve, presented at follow-up an unsatisfactory results due to an "adding on" phenomenon. The statistical analysis confirmed that this phenomenon was correlated with The King IV curve (P = 0.043; Chi-square test) and that the only predictive parameter for its onset was the LIV-SV difference (odds ratio = 0.093; with a confidence interval of 0.008-1): every time that in King IV curve type the LIV was three or more levels shorter than the stable vertebra at follow-up the "adding on" phenomenon was present. The authors conclude that Lenke's type 1 with modifier A includes two kinds of curves, King III and King IV and that the Lenke's type 2 curves and King V with the lumbar curve not crossing the middle line have a similar behavior. Therefore, it is of authors' opinion that "the adding on phenomenon" could be prevented by more rigidly defining K. IV versus K. III curves. In Lenke's 1/2 A-K. IV/V type with the rotation of the first vertebra just below the thoracic lower EV in the same direction as the thoracic curve, and when SV and EV show more than two levels of difference, it is necessary to extend the lower fusion down to L2 or L3 (not more than two levels shorter than the SV). Whereas in Lenke's 1/2 A-K. III/V with the rotation of the first proximal vertebra of lumbar curve in the opposite direction to the thoracic apex and when SV and EV show not more than two level gap differences, the position of the lowest instrumented vertebra can be two or three levels shorter than the stable vertebra with satisfactory postoperative spinal balance. Therefore, the stable vertebra and the rotation of lumbar curve are considered to be a reliable guide for selecting the lower level of fusion.

Juvenile idiopathic scoliosis treated with posterior arthrodesis and segmental pedicle screw instrumentation before the age of 9 years: a 5-year follow-up

Study design

Retrospective study.

Objective

To evaluate the radiological results of fusion with segmental pedicle screw fixation in juvenile idiopathic scoliosis with a minimum 5-year follow-up.

Summary of background data

Progression of spinal deformity after posterior instrumentation and fusion in immature patients has been reported by several authors. Segmental pedicle screw fixation has been shown to be effective in controlling both coronal and sagittal plane deformities. However, there is no long term study of fusion with segmental pedicle screw fixation in these group of patients.

Methods

Seven patients with juvenile idiopathic scoliosis treated by segmental pedicle screw fixation and fusion were analyzed. The average age of the patients was 7.4 years (range 5–9 years) at the time of the operation. All the patients were followed up 5 years or more (range 5–8 years) and were all Risser V at the most recent follow up. Three dimensional reconstruction of the radiographs was obtained and 3DStudio Max software was used for combining, evaluating and modifying the technical data derived from both 2d and 3d scan data.

Results

The preoperative thoracic curve of 56 ± 15° was corrected to 24 ± 17° (57% correction) at the latest follow-up. The lumbar curve of 43 ± 14° was corrected to 23 ± 6° (46% correction) at the latest follow-up. The preoperative thoracic kyphosis of 37 ± 13° and the lumbar lordosis of 33 ± 13° were changed to 27 ± 13° and 42 ± 21°, respectively at the latest follow-up. None of the patients showed coronal decompensation at the latest follow-up. Four patients had no evidence of crankshaft phenomenon. In two patients slight increase in Cobb angle at the instrumented segments with a significant increase in AVR suggesting crankshaft phenomenon was seen. One patient had a curve increase in both instrumented and non instrumented segments due to incorrect strategy.

Conclusion

In juvenile idiopathic curves of Risser 0 patients with open triradiate cartilages, routine combined anterior fusion to prevent crankshaft may not be warranted by posterior segmental pedicle screw instrumentation.

How to determine the upper level of instrumentation in Lenke types 1 and 2 adolescent idiopathic scoliosis: a prospective study of 132 patients

BACKGROUND

The selection of fusion levels continues to be controversial in adolescent idiopathic scoliosis (AIS). The classifications of King and Lenke remain the most widely used, but recent studies have demonstrated their shortcomings, including poor interobserver reproducibility. We propose a method of preoperative planning that is independent of anatomical classifications, based on the anticipated effect of curve reduction. The objectives of this preoperative strategy are (1) to achieve satisfactory T1 tilt and shoulder balance and (2) to restore balance in the coronal and sagittal planes. The purpose of the present study was to evaluate the results of our strategy of deciding the proximal level of arthrodesis in Lenke types 1 and 2 AIS.

METHODS

We included 132 adolescents operated on for thoracic AIS by posterior instrumentation. The choice of the proximal fusion level was based on preoperative analysis of the rigidity of the proximal curvature, T1 tilt, and shoulder balance. The preoperative, postoperative, and last follow-up radiographs were digitized then analyzed using computer software. Radiological parameters were compared using paired t tests.

RESULTS

Average age at the time of surgery was 15.2 years (SD, 1.7 years). Mean follow-up was 30.2 months. The clavicle angle and T1 tilt were significantly improved in both Lenke types 1 and 2 curves. No correlation was found between T1 tilt and shoulder balance. At last follow-up, 89% of the patients satisfied all criteria for balance.

CONCLUSIONS

The results of the present preoperative strategy, to which we adhered in 97% of cases, are encouraging and show that the systematic instrumentation of the entire proximal curvature is not justified in Lenke type 2 curves. However, long-term consequences of the residual T1 tilt need to be studied further.

Axial plane lumbar responses after anterior selective thoracic fusion for main thoracic adolescent idiopathic scoliosis

Study Design

A retrospective radiographic study.

Purpose

To evaluate the axial plane lumbar responses after anterior selective thoracic fusion (STF) in patients with main thoracic adolescent idiopathic scoliosis (MT-AIS).

Overview of Literature

Anterior scoliosis surgery induces more MT derotation through disc preparation than posterior surgery.

Methods

Twenty-eight MT-AIS patients treated with STF were evaluated after a minimum follow-up (FU) of 2 years. The MT and lumbar coronal angles, as well as the MT and lumbar rotational angles at the most rotated vertebrae were measured.

Results

At the last FU, the MT coronal correction and derotation rates were 65% and 41%, respectively. The lumbar coronal correction rate was 61% but there was minimal lumbar derotation (2%). Nine cases were decompensated (coronal balance >10 mm). After surgery, the compensated and decompensated groups showed similar MT coronal and axial correction rates. During the FU, the MT and lumbar apecies rotated in the same direction (r=0.443). In addition, significant MT derotation occurred in the decompensated group with increasing lumbar rotational correction loss. At the last FU, while the MT coronal correction was similar between the two groups, there was more MT derotation in the decompensated group. Furthermore, the MT rotational change was strongly associated with the coronal C7 plumb line position (r=0.728).

Conclusions

After anterior STF in patients with MT-AIS, the final MT derotation is strongly associated with the coronal C7 plumb line position. During the FU, the excessive MT derotation in the decompensated group was attributed to excessive lumbar rotational correction loss.