Pre- and post-operative sagittal balance in idiopathic scoliosis: a comparison over the ages of two cohorts of 132 adolescents and 52 adults

Hybrid vs all pedicle screws constructs in adolescent idiopathic scoliosis: a metaanalysis of clinical and radiological outcomes

BACKGROUND

Adolescent idiopathic scoliosis (AIS) affects around 1 to 3% of young individuals, leading to spinal deformities typically exceeding a Cobb angle of 10 degrees without congenital or neuromuscular causes. Advances in treatment now include various surgical techniques such as posterior fusion utilizing all-pedicle screw constructs or hybrid constructs.

METHODS

PubMed, Cochrane, and Google Scholar (pages 1-20) were searched up until February 2024. Comparative studies in which the cohort was separated into two groups (HC and PSC) were included. Data consisting of, surgery-related outcomes, sagittal radiographic outcomes, coronal radiographic outcomes, and patient-reported outcomes, was extracted and compared.

RESULTS

Twenty-eight studies including 3435 patients were included. Higher rates of complications (Odds-Ratio = 1.99, p < 0.00001) and reoperations (Odds-Ratio = 2.82, p < 0.00001) were seen in the hybrid group. Better radiographic coronal correction was seen in the PSC group in both the major curve (Mean Difference = 5.97, p < 0.00001) and the secondary curve (Mean Difference = - 10.73, p < 0.0001). However, restoration of sagittal alignment was better in the HC group when assessing thoracic kyphosis (Mean Difference = 2.97, p = 0.02) and lumbar lordosis (Mean Difference = 3.17, p = 0.005).

CONCLUSION

While all-pedicle screw constructs demonstrated greater stability in AIS compared to hybrid constructs, resulting in reduced rates of reoperations and complications, as well as improved correction of major and secondary curves, they were unable to fully restore optimal sagittal alignment.

Surgery for Spinal Stenosis in Achondroplasia: Causes of Reoperation and Reduction of Risks

BACKGROUND

Individuals with achondroplasia are prone to symptomatic spinal stenosis requiring surgery. Revision rates are thought to be high; however, the precise causes and rates of reoperation are unknown. The primary aim of this study is to investigate the causes of reoperation after initial surgical intervention in individuals with achondroplasia and spinal stenosis. In addition, we report on surgical techniques aimed at reducing the risks of these reoperations.

METHODS

A retrospective review was conducted over an 8-year period of all patients with achondroplasia at a single institution that serves as a large referral center for patients with skeletal dysplasias. Patients with achondroplasia who underwent spinal surgery for stenosis were identified and the need for revision surgery was studied. Data collected included demographic, surgical, and revision details. Fisher exact test was used to determine if an association existed between construct type and the need for revisions.

RESULTS

Thirty-three of the 130 (22%) patients with achondroplasia required spinal stenosis surgery. Twenty-four individuals who met the criteria were selected for analysis. The initial spine surgery was at an average age of 18.7 years (SD: 10.1 y). Nine patients (38%) required revision surgeries, and 3 required multiple revisions. Five of 9 (56%) of the revisions had primary surgery at an outside institution. Revision surgeries were due to caudal pseudarthrosis (the distal instrumented segment) (8), proximal junctional kyphosis (PJK) (7), and new neurological symptoms (7). There was a significant association found between construct type and the need for revision (P=0.0111). The pairwise comparison found that short fusions were significantly associated with the need for revision compared with the interbody group (P=0.0180). PJK was associated with short fusions when compared with the long fusion group (P=0.0294) and the interbody group (P=0.0300). Caudal pseudarthrosis was associated with short fusions when compared with the interbody group (P=0.0015). Multivariate logistic regression found long fusion with an interbody was predictive of and protective against the need for revision surgery (P=0.0246). To date, none of the initial cases that had long fusions with caudal interbody required a revision for distal pseudarthrosis.

CONCLUSIONS

In patients with achondroplasia, the rate of surgery for spinal stenosis is 22% and the risk of revision is 38% and is primarily due to pseudarthrosis, PJK, and recurrent neurological symptoms. Surgeons should consider discussing spinal surgery as part of the patient's life plan and should consider wide decompression of the stenotic levels and long fusion with the use of an interbody cage at the caudal level in all patients to reduce risks of revision.

LEVEL OF EVIDENCE

Level IV-Retrospective case series.

Influence of thoracolumbar kyphosis on postoperative spinal alignment in patients with Lenke type 5C adolescent idiopathic scoliosis

PURPOSE

This study aimed to examine the changes in thoracolumbar kyphosis (TLK) following correction surgery in patients with Lenke type 5C adolescent idiopathic scoliosis (AIS) and to evaluate its influence on postoperative spinal alignment and clinical outcomes.

METHODS

Sixty-six patients with Lenke type 5C AIS were included and followed up for a minimum of 5 years after surgery. First, the patients were divided into two groups according to the preoperative TLK angle (Study 1; Kyphosis and Lordosis group). The patients were further classified into two groups according to the presence or absence of postoperative changes in TLK (Study 2; Changed and Maintained groups). Finally, the outcome variables were compared between these groups and analyzed for spinal alignment and clinical outcomes.

RESULTS

In Study 1, patients demonstrated a significant kyphotic change in the Lordosis group and a significant lordotic change in the Kyphosis group postoperatively. No statistically significant differences were found between the two groups when comparing the pre- and postoperative coronal and sagittal alignment. In Study 2, there were no statistically significant differences between the Changed and the Maintained groups in each spinal alignment pre- and postoperatively. Each domain of the Scoliosis Research Society 22-item questionnaire remained unchanged at 5 years postoperation.

CONCLUSION

In many patients with Lenke type 5C AIS, TLK changed significantly and approached 0° after surgery. However, the magnitude of the preoperative TLK and the presence or absence of improvement did not affect postoperative spinal alignment. Furthermore, the patients had satisfactory clinical outcomes irrespective of TLK modification.

LEVEL OF EVIDENCE

III.

Clinical and radiographic outcomes following correction of idiopathic scoliosis in adolescence vs young adulthood

PURPOSE

The natural history of adolescent idiopathic scoliosis (AIS) has been well documented, but the impact of age at the time of surgical correction is relatively understudied. In this study, we matched patients undergoing surgical correction of adult idiopathic scoliosis (AdIS) with a cohort of AIS patients to compare: (1) coronal and sagittal radiographic correction, (2) operative variables, and (3) postoperative complications.

METHODS

A single-institution scoliosis registry was queried for patients undergoing idiopathic scoliosis surgery from 2000-2017.

INCLUSION CRITERIA

patients with idiopathic scoliosis, no previous spine surgery, and 2-year follow-up. AdIS patients were matched 1:2 with AIS patients based on Lenke classification and curve characteristics. Independent sample t-test and Chi-square test was used to analyze the data.

RESULTS

31 adults underwent surgical correction of idiopathic scoliosis and were matched with 62 adolescents. Mean age of adults was 26.2 ± 11.05, mean BMI was 25.6 ± 6.0, and 22 (71.0%) were female. Mean age of adolescents was 14.2 ± 1.8, mean BMI was 22.7 ± 5.7, and 41(66.7%) were female. AdIS had significantly less postoperative major Cobb correction (63.9% vs 71.3%, p = 0.006) and final major Cobb correction (60.6% vs 67.9%, p = 0.025). AdIS also had significantly greater postoperative T1PA (11.8 vs 5.8, p = 0.002). AdIS had longer operative times (p = 0.003), higher amounts of pRBCs transfused (p = 0.005), longer LOS (p = 0.016), more ICU requirement (p = 0.013), higher overall complications (p < 0.001), higher rate of pseudarthrosis (p = 0.026), and more neurologic complications (p = 0.013).

CONCLUSION

Adult patients undergoing surgical correction of idiopathic scoliosis had significantly worse postoperative coronal and sagittal alignment when compared with adolescent patients. Adult patients also had higher rates of complications, longer operative times, and longer hospital stays.

LEVEL OF EVIDENCE

III.

How to make a more optimal surgical plan for Lenke 5 adolescent idiopathic scoliosis patients: a comparative study based on the changes of the sagittal alignment and selection of the lowest instrumented vertebra

BACKGROUND

The treatment of patients with Lenke 5 adolescent idiopathic scoliosis (AIS) is closely related to the pelvic because the spine-pelvis is an interacting whole. Besides, the choice of fusion segment is a significant issue; with the optimal choice, there will be fewer complications and restoring the pelvic morphology to some extent. This study aims to analyze the impact of changes in sagittal parameters and selection of the lowest instrumented vertebra (LIV) on spine and pelvic morphology for better surgical strategy.

METHOD

Ninety-four patients with Lenke 5 AIS who underwent selective posterior thoracolumbar/lumbar (TL/L) curve fusion were included in the study and grouped according to pelvic morphology and position of LIV. Spinopelvic parameters were measured preoperatively, postoperatively, and at the latest follow-up. The patient's preoperative and last follow-up quality of life was assessed with the MOS item short-form health survey (SF-36) and scoliosis research society 22-item (SRS-22).

RESULT

Patients being posterior pelvic tilt had the oldest mean age (P = 0.010), the smallest lumbar lordosis (LL) (P = 0.036), the smallest thoracic kyphosis (TK) (P = 0.399) as well as the smallest proximal junctional angle (PJA) while those being anterior pelvic tilt had the largest PJA. The follow-up TK significantly increased in both groups of anterior and normal pelvic tilt (P < 0.039, P < 0.006) while no significant changes were observed in the posterior pelvic tilt group. When LIV is above L4, the follow-up PJA was larger than other groups (P = 0.049, P = 0.006). When LIV is below L4, the follow-up TK and PT were larger and LL was smaller than other groups(P < 0.05). The SF-36 and SRS-22 scores were better in the LIV = L4 group than in other groups at the last follow-up (P < 0.05).

CONCLUSION

The correction of TK and LL after surgery can improve pelvic morphology. Besides, LIV is best set at L4, which will facilitate the recovery of TK, the improvement of symptoms, and the prevention of complications and pelvic deformities. Level of evidence Level III.

[Increased risk of thoracic hypokyphosis after posterior spinal correction and fusion in adolescent idiopathic scoliosis with thoracic double curve]

BACKGROUND

Adolescent idiopathic scoliosis (AIS) is often associated with thoracic hypokyphosis or even lordosis.

OBJECTIVES

To analyze the influence of posterior correction and fusion in thoracic, structurally double-curved AIS.

MATERIAL AND METHODS

Out of 127 thoracic AIS (Lenke types 1 and 2) recorded prospectively, idiopathic double thoracic curve AIS were analyzed retrospectively. Surgery 2010-2019 with pedicle screw double rod systems in a scoliosis center. Follow-up (FU) at least 2 years. Frontal and sagittal angles (whole-spine radiographs, 2 planes): thoracic curve (MK), proximal-thoracic curve (PK) and lumbar curve (LK), thoracic kyphosis (TK), lumbar lordosis (LL).

STATISTICAL ANALYSIS

values as MW ± SD, students t‑test (significance a = 0.05), Pearson's correlation, sub-analysis with sagittal modifiers (-, N, +).

RESULTS

A total of 47 AIS-double thoracic curve were identified, mean FU 29.3 ± 12.2 months, mean age 14 ± 1.5 years. The mean correction (FU-preop) of MK was 67%, PK 53%, LK 73%, each significant, (p < 0.05). On average, TK (FU-preop) decreased by -6.5 ± 11.6° (p < 0.05), no significant change from FU (p = 0.6). TK (FU-preop) increased by 8.6 ± 5.0° (p < 0.05) in hypokyphotic cases, significantly decreased by -4.8 ± 9.6° in normokyphotic AIS and -25.3 ± 11.1° in hyperkyphotic cases, respectively (p < 0.05). In hypokyphosis: moderately strong correlation between correction PK (r = -0.5) and spontaneous correction LK (r = 0.8) (frontal plane) and change from pre- to postop TK (sagittal plane) (p < 0.05). Moderate correlation for hyperkyphosis: correction PK (r = -0.5) and postop TK (p < 0.05). No relevant correlations for normokyphosis. 17% had postop hypokyphosis, of which 0% had preop hypokyphosis. Rod diameter (5.5 mm vs. 6 mm) had no significant effect on TC.

CONCLUSIONS

Posterior instrumented correction and fusion (pedicle screw dual rod systems) can significantly correct both lateral curves in idiopathic double thoracic curves, although it is associated with an increased risk of postop thoracic hypokyphosis, especially in preoperatively normokyphotic patients.

An Analysis of Whether a New Formula Can Predict Proximal Junctional Failure in Adult Spinal Deformity Patients with Global Kyphosis

OBJECTIVE

A new formula containing terms for age and sagittal curvature reported by the International Spine Study Group is ideal lumbar lordosis (iLL) = pelvic incidence - 0.3 thoracic kyphosis - 0.5Age + 10. However, there are no reports of whether proximal junctional failure (PJF) can be predicted using this formula. We assessed the utility of this formula in PJF in patients with adult spinal deformity with global kyphosis using the Roussouly classification.

METHODS

Forty-four patients with adult spinal deformity global kyphosis (mean age 70.0 years) who underwent multiple levels of lateral lumbar interbody fusion combined with posterior instrumentation were included. Patients were divided into 2 groups: PJF and non-PJF. Demographic, surgical, and radiological parameters were compared. The iLL was calculated according to the new formula, and spinal parameters were compared preoperatively, immediately after, and at the final follow-up.

RESULTS

PJF occurred in 11 of 44 (25.0%) patients. Patients with PJF had a large preoperative and postoperative TK, but there was no statistically significant difference in iLL between PJF and non-PJF patients (33.4° vs. 30.2°, P = 0.357). In addition, there was no statistically significant difference in LL and iLL changes (ΔiLL) immediately after surgery (19.0° vs. 23.4°, P = 0.379). Furthermore, there was no correlation between ΔiLL immediately after surgery and at the final follow-up and the proximal junctional angle at the final follow-up.

CONCLUSIONS

The results of ΔiLL suggest that overcorrection needs to be addressed but that this new formula, including age adjustment, may not predict PJF.

Restoration of thoracic kyphosis in adolescent idiopathic scoliosis with patient-specific rods: did the preoperative plan match postoperative sagittal alignment?

PURPOSE

To determine if the planned sagittal profile for thoracic kyphosis (TK) restoration was achieved after adolescent idiopathic scoliosis (AIS) surgery using a novel hybrid construct with apical double bands and precontoured patient-specific rods (PSR) made according to the detailed surgical plan for the desired sagittal plane.

METHODS

AIS patients with a Lenke type 1-4 primary right thoracic curve who underwent corrective surgery by a single surgeon and had minimum 24-month follow-up were analyzed retrospectively from a prospective database. All patients underwent simultaneous translation on two rods with apical double bands and PSR. Clinical outcomes in terms of sagittal 2D TK (T4-T12), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), PI-LL mismatch, rod angle, and rod deflection were compared between preoperative, planned, and 24-month data, while 3D apical rotation, 3D TK (T5-T12), sagittal thoracolumbar angle, degree of curvature at L1-L4 and L4-S1, proximal junctional angle, and distal junctional angle were compared at baseline and at 6 and 24 months postoperatively. SRS-22 questionnaire scores were obtained at baseline and 24 months postoperatively.

RESULTS

Forty-eight patients were included. Study patients had a median coronal thoracic curve of 62.7° preoperatively and 22.4° at 24-month follow-up (p < 0.001). Median TK gain was 6.5° for the entire cohort (n = 48) and 19.1° in the Lenke type 1 and 2 hypokyphotic subgroup (n = 14). Both groups had no significant changes between planned and 24-month TK (p = 0.068 and p = 0.943, respectively), rod angle (p = 0.776 and p = 0.548, respectively), or rod deflection (p = 0.661 and p = 0.850, respectively). For the overall study cohort, median LL gain was 7.0° (p < 0.001), 3D apical derotation was 10.7° (p < 0.001), and change in 3D TK was 36° (p < 0.001). No instance of proximal junctional kyphosis was observed. SRS-22 scores for pain, self-image, and satisfaction differed significantly between the preoperative and 24-month follow-up time-points.

CONCLUSIONS

With sagittal plane planning, desired TK, improved reciprocal changes in LL, and minimal changes in rod shape can be achieved in patients with AIS.

Cervical sagittal alignment is influenced by changes in thoracic and lumbar sagittal alignments after correction surgery in patients with lenke type 6 adolescent idiopathic scoliosis

Background

Few studies have examined the changes in cervical sagittal alignment (CSA) and its relationship with other sagittal alignments in AIS patients with major thoracolumbar/lumbar (TL/L) curve who underwent correction surgery. This study investigated the radiographical changes in CSA after correction surgery in patients with Lenke type 6 adolescent idiopathic scoliosis (AIS) and assess any possible factors affecting postoperative CSA.

Methods

Forty-four patients with Lenke type 6 AIS (3 males and 41 females, mean age at surgery of 15.6 ± 2.8 years) who could be followed up for 3 years after correction surgery were included in this study. Variations of outcome variables were analyzed in various spinal sagittal parameters using radiographic outcomes. Univariate correlation analyses were used to evaluate possible factors influencing the postoperative CSA. The Scoliosis Research Society (SRS)-22 questionnaires and the Oswestry Disability Index (ODI) were used for clinical evaluation, and the changes between pre- and 3-year post-operation were compared.

Results

The Cobb angle of the major and minor curve was significantly improved after correction surgery. Furthermore, CSA, such as C2-7 angle and T1 slope, changed significantly postoperatively. The magnitude of coronal curve correction did not affect CSA postoperatively, while the postoperative TK, T10-L2 kyphosis and LL were significantly correlated with the postoperative C2-7 angle, respectively. None of the patients in this study complained of neck or low back pain during the period up 3 years after the operation. Comparing each domain of SRS-22 or ODI score, these were unchanged between pre-, 1-year, and 3-year post-operation, with no statistically significant differences.

Conclusions

CSA changed significantly after correction surgery, and cervical kyphosis indicated a tendency to decrease in Lenke type 6 AIS patients, which was associated with an improvement in thoracic and lumbar sagittal alignment, not correction for coronal deformity.

Geriatric relationship with inpatient opioid consumption and hospital outcomes after open posterior spinal fusion for adult spine deformity

OBJECTIVE

As the population ages, increasing attention has been placed on identifying risk factors for poor surgical outcomes in the elderly. The aim of this study was to assess the impact of geriatric status on inpatient narcotic consumption and healthcare resource utilization in patients undergoing spinal fusion for adult spinal deformity.

METHODS

A retrospective study was performed using the Premier Healthcare Database (2016-2017). All adult patients who underwent thoracic/thoracolumbar fusion for spine deformity were identified using ICD-10-CM codes. Patients were categorized by age: 18-49 years-old (Young), 50-64 years-old (Older), and 65 + years-old (Geriatric). Patient demographics, comorbidities, hospital characteristics, intraoperative variables, adverse events (AEs), and healthcare resource utilization were assessed. Increased inpatient opioid use was categorized by MME (morphine milligram equivalents) admission consumption greater than the 75th percentile of the cohort. Multivariate logistic regression analysis was used to identify independent predictors of increased opioid usage, increased cost, and non-routine discharge (NRD).

RESULTS

Of the 1831 patients identified, 199 (10.9 %) were in the Young cohort, 599 (32.7 %) were in the Older cohort, and 1033 (56.4 %) were in the Geriatric cohort. The Geriatric cohort had a greater proportion of patients who were Non-Hispanic White (p < 0.001) and government-insured (p < 0.001). Comorbidities [CCI (p < 0.001)] and frailty [mFI-5 (p < 0.001)] increased with age. AEs occurred at similar rates between cohorts. A greater proportion of Older patients consumed an increased amount of MMEs during their hospital stay (Young: 24.9 % vs. Older: 33.1 % vs. Geriatric: 20.2 %, p < 0.001). A greater proportion of Geriatric patients experienced high costs (p = 0.018), longer LOS (p = 0.011), and 30-day readmission (p = 0.004) compared to other cohorts. A significantly greater proportion of the Geriatric cohort experienced NRD (Young: 25.3 % vs. Older: 58.8 % vs. Geriatric: 83.0 %, p < 0.001) On multivariate analysis, Geriatric age was independently associated with NRD (OR: 11.59, p < 0.001), and inversely associated with increased MME use (OR: 0.66, p = 0.038). However, Older age was independently associated with increased MME use (OR: 1.58, p = 0.026) and NRD (OR: 4.27, p < 0.001), though not increased cost (OR: 1.49, p = 0.077).

CONCLUSION

Our study demonstrates that geriatric patients may require fewer opioids than younger patients but require greater resource utilization on discharge. Additional studies investigating the impact of aging are necessary to improve patient risk stratification, healthcare delivery, and patient outcomes.

At Mean 30-Year Follow-Up, Cervical Spine Disease Is Common and Associated with Thoracic Hypokyphosis after Pediatric Treatment of Adolescent Idiopathic Scoliosis

Patients with adolescent idiopathic scoliosis (AIS) often have reduced sagittal thoracic kyphosis (hypokyphosis) and cervical lordosis causing an uneven distribution of physiologic load. However, the long-term consequences of hypokyphosis in AIS patients have not been previously documented. To evaluate whether uneven load distribution leads to future complications in patients with AIS, we conducted a retrospective chart review and subsequently surveyed 180 patients treated for idiopathic scoliosis between 1975 and 1992. These patients all had a minimum follow-up time of 20 years since their treatment. We observed a ten-fold increase in the incidence of anterior cervical discectomy and fusion (ACDF) compared to reported rates in the non-pathologic population. Out of the 180 patients, 33 patients met the criteria and returned for follow-up radiographs. This population demonstrated a statistically significant increased rate of cervical osteoarthritis and disc degeneration. Overall, our study suggests that hypokyphosis in patients with AIS presents with increased rates of cervical spine degeneration and dysfunction, suggesting that these patients may require additional follow-up and treatment.

Hip replacement improves lumbar flexibility and intervertebral disc height - a prospective observational investigation with standing and sitting assessment of patients undergoing total hip arthroplasty

PURPOSE

The pathogenic mechanism of the hip-spine syndrome is still poorly elucidated. Some studies have reported a reduction in low back pain after total hip arthroplasty (THA). However, the biomechanical mechanisms of THA acting on the lumbar spine are not well understood. The aim of the study is to evaluate the influence of THA on (1) the lumbar lordosis and the lumbar flexibility and (2) the lumbar intervertebral disc height.

METHODS

A total of 197 primary THA patients were prospectively enrolled. Pre- and post-operative biplanar stereoradiography was performed in standing and sitting positions. Spinopelvic parameters (lumbar lordosis (LL), pelvic tilt, sacral slope, pelvic incidence), sagittal spinal alignment (sagittal vertical axis, PI-LL mismatch (PI-LL)) and lumbar disc height index (DHI) for each segment (L1/2 to L5/S1) were evaluated. The difference between standing and sitting LL (∆LL = LL_standing - LL_sitting) was determined as lumbar flexibility. Osteochondrosis intervertebralis was graded according to Kellgren and Lawrence (0-4), and patients were assigned to subgroups (mild: 0-2; severe: 3-4).

RESULTS

Lumbar flexibility increased significantly after THA (pre: 22.04 ± 12.26°; post: 25.87 ± 12.26°; p < 0.001), due to significant alterations in LL in standing (pre: 51.3 ± 14.3°; post: 52.4 ± 13.8°; p < 0.001) and sitting (pre: 29.4 ± 15.4°; post: 26.7 ± 15.4°; p = 0.01). ∆LL increased significantly in both subgroups stratified by osteochondrosis (pre/post: ΔLL_mild: 25.4 (± 11.8)/29.4 ± 12.0°; p < 0.001; ΔLL_severe: 17.5 (± 11.4)/21.0 ± 10.9°; p = 0.003). The DHI increased significantly from pre-operatively to post-operatively in each lumbar segment. PI-LL mismatch decreased significantly after THA (pre: 3.5°; post: 1.4°; p < 0.001).

CONCLUSION

The impact of THA on the spinopelvic complex was demonstrated by significantly improved lumbar flexibility and a gain in post-operative disc height. These results illustrate the close interaction between the pelvis and the vertebral column. The investigation provides new insights into the biomechanical patterns influencing the hip-spine syndrome.

Mid and lower thoracic kyphosis changes during adulthood: the influence of age, sex and thoracic coronal curvature

INTRODUCTION

There is conflicting data on how thoracic kyphosis changes throughout adulthood. We evaluated mid and lower thoracic kyphosis (MTK) in various age groups and the influence of age, sex and coronal curve (CC) on MTK.

MATERIAL AND METHODS

We studied 1323 patients 15-80 years-old (54.4% females) previously evaluated with chest radiographs. We established three groups: patients 15-40 (group 1); 41-60 (group 2) and 61-80 years old (group 3). MTK (T5-T12) and CC were measured using Cobb's method. We established differences in MTK between groups using ANOVA with Bonferroni correction. We performed a correlation analysis of MTK with age and CC, and a linear regression analysis to determine if age, sex and CC independently predicted MTK.

RESULTS

MTK increased with older age: mean MTK group 1 = 23.4°; group 2 = 27.9° and group 3 = 34.4°, p < 0.01. The increase in MTK was observed in both genders. Scoliosis was more common in females (15.4%) than in males (6.7%), p < 0.01. MTK was correlated with age (r = 0.4; p < 0.01) and slightly correlated with CC (r = 0.07, p < 0.01). MTK was larger in females than in males (29.1° vs. 27.6°, p < 0.01). Age (ß-coefficient = 0.26) and CC (ß-coefficient = 0.14), but not sex, independently influenced MTK in the regression analysis.

CONCLUSION

MTK increases with advancing age during adulthood in both genders; CC, but not sex, was an independent predictor of MTK.

Sagittal morphology of the cervical spine in adolescent idiopathic scoliosis: a retrospective case-control study

BACKGROUND

To investigate the relationship between sagittal alignment and coronal deformity in patients with adolescent idiopathic scoliosis (AIS) through analysis of the spinal imaging data.

METHODS

Four hundred and fifty-four AIS patients who underwent anteroposterior and lateral radiography of the while spine were enrolled, and the spinal parameters of Cobb angle, cervical lordosis, C1-C2 angle, T1 slope, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt (PT), pelvic incidence (PI), cervical sagittal vertical axis (SVA), and spinal SVA were analyzed.

RESULTS

The patients were divided into two groups according to the size of the Cobb angle: group A (Cobb angle ≤45°, n=414) and group B (Cobb angle >45°, n=40). In group A, the Cobb angle was in a medium negative correlation with the cervical lordosis angle (r=-0.637, P<0.001), a weak positive correlation (|r|<0.3, P<0.05) with C1-C2 angle, T1 slope and thoracic kyphosis. In group B, the Cobb angle was in a mild positive correlation (P<0.05) with PT (r=0.398) and PI (r=0.360). The cervical lordosis angle was significantly (P<0.05) different between male and female patients in both groups. In Group A, the cervical lordosis angle was in a significantly (P<0.01) positive correlation with the T1 slope (r=0.586), thoracic kyphosis (r=0.490), and sagittal vertical axis (r=0.135), and a significantly (P<0.01) negative correlation with cervical sagittal vertical axis (r=-0.128) and C1-C2 angle (r=-0.155). In group B, the cervical lordosis angle was in a significantly (P<0.05) positive correlation with T1 slope (r=0.661), thoracic kyphosis (r=0.608), lumbar lordosis (r=0.425), sacral slope (r=0.434), and sagittal vertical axis (r=0.335).

CONCLUSIONS

In AIS patients with the Cobb angle ≤45º, a significant negative correlation exists between the cervical lordosis and the Cobb angle. The sagittal morphology of the cervical spine in AIS patients is affected by the spinal coronal deformity, which plays an important role in the treatment of AIS.

Lumbopelvic postural differences in adolescent idiopathic scoliosis: A pilot study

BACKGROUND

A primary etiology of adolescent idiopathic scoliosis (AIS) is currently unknown, but poor postural control of the spinal extensor musculature has been identified as an AIS risk factor. Identifiable postural differences would aid in advancing the precise postural behaviors that should be modified during Physiotherapy Scoliosis Specific Exercise (PSSE) to help limit the progression of AIS.

RESEARCH QUESTION

Are there any determinable differences in lumbopelvic posture or range of motion between subjects with AIS and controls?

METHODS

This prospective cohort pilot study consisted of 53 subjects (27 AIS and 26 control) aged 11-17 years. Subjects had their lumbopelvic posture assessed and monitored using the ViMove DorsaVi sensor package. All subjects underwent a live assessment to obtain initial lumbopelvic (LP) range of motion (ROM) measurements. Subjects were then monitored while continuing with normal activities of daily living (ADLs) for 12 h. With an alpha level of 0.05, nonparametric analyses were performed for each variable via a Mann-Whitney U-test.

RESULTS

During the live assessment, controls exhibited a significantly greater anterior pelvic tilt ROM in the sitting position than the AIS group (p = 0.0433). When compared to female controls, females with AIS had a sitting pelvic tilt ROM that was significantly more retroverted (p = 0.0232) and less anteverted (p = 0.0010). During ADLs, female controls exhibited a higher total number of extension events than their female with AIS (p = 0.0263). These associations did not strengthen with greater spinal deformity.

SIGNIFICANCE

This work demonstrates postural differences between patients with AIS and controls. Further study is necessary to determine why patients with AIS adopt these postures, and if PSSEs can be utilized to limit the progression of AIS.

Risk Factors of Postoperative Shoulder Imbalance in Adolescent Idiopathic Scoliosis: The Role of Sagittal Spinopelvic Parameters and Upper Instrumented Vertebrae Selection

STUDY DESIGN

This is a retrospective study.

OBJECTIVE

To determine (1) the independent risk factors of postoperative shoulder imbalance (PSI) after adolescent idiopathic scoliosis (AIS) correction surgery; and (2) whether the level of upper instrumented vertebrae (UIV) affects postoperative shoulder balance.

SUMMARY OF BACKGROUND DATA

PSI is an important outcome of AIS correction surgery as it influences a patient's appearance and satisfaction. However, risk factors for PSI remain controversial and there are currently no studies evaluating the effect of sagittal spinopelvic parameters on PSI. Previous studies on the relationship between the level of UIV and PSI have also reported conflicting results.

MATERIALS AND METHODS

Sixty-nine AIS patients undergoing correction surgery at a single institution were retrospectively reviewed. Radiographic parameters were measured on anteroposterior and lateral x-rays preoperatively, immediate postoperatively, and 12 months postoperatively. At 1 year follow-up, patients were divided into 2 groups based on their radiographic shoulder height (RSH): (1) PSI group (RSH ≥20 mm) and (2) non-PSI group (RSH <20 mm).

RESULTS

On multivariate regression analysis, a lower postoperative main thoracic curve (MTC) [odds ratio (OR): 0.702, 95% confidence interval (CI): 0.519-0.949, P=0.022], greater percentage correction of MTC (OR: 1.526, 95% CI: 1.049-2.220, P=0.027) and higher postoperative sacral slope (OR: 1.364, 95% CI: 1.014-1.834, P=0.040) were identified as independent risk factors of PSI. When preoperative, postoperative, and absolute change in shoulder parameters were compared across the level of UIV, no significant differences were found regardless of the radiographic shoulder parameter analyzed.

CONCLUSIONS

Lower postoperative MTC, greater percentage correction of MTC and higher postoperative sacral slope were independent risk factors of PSI. Shoulder balance and symmetry were not affected by the level of UIV selected. Relative curve correction is a more important consideration than UIV to avoid PSI after AIS correction surgery.

LEVEL OF EVIDENCE

III.

Global malalignment in adolescent idiopathic scoliosis: the axial deformity is the main driver

PURPOSE

To evaluate the global alignment of non-operated subjects with adolescent idiopathic scoliosis.

METHOD

A total of 254 subjects with AIS and 64 controls underwent low dose biplanar X-rays and had their spine, pelvis, and rib cage reconstructed in 3D. Global alignment was measured in the sagittal and frontal planes by calculating the OD-HA angle (between C2 dens to hip axis with the vertical). Subjects with AIS were classified as malaligned if the OD-HA was > 95th percentile relative to controls.

RESULTS

The sagittal OD-HA in AIS remained within the normal ranges. In the frontal plane, 182 AIS were normally aligned (Group 1, OD-HA = 0.9°) but 72 were malaligned (Group 2, OD-HA = 2.9°). Group 2 had a more severe spinal deformity in the frontal and horizontal planes compared to Group 1 (Cobb: 42 ± 16° vs. 30 ± 18°; apical vertebral rotation AVR: 19 ± 10° vs. 12 ± 7°, all p < 0.05). Group 2 subjects were mainly classified as Lenke 5 or 6. 19/72 malaligned subjects had a mild deformity (Cobb < 30°) but a progressive scoliosis (severity index ≥ 0.6). The frontal OD-HA angle was found to be mainly determined (adjusted-R² = 0.22) by the apical vertebral rotation and secondarily by the Lenke type.

CONCLUSIONS

This study showed that frontal malalignment is more common in distal major structural scoliosis and its main driver is the apical vertebral rotation. This highlights the importance of monitoring the axial plane deformity in order to avoid worsening of the frontal global alignment.

Effects of posterior hemivertebra resection and short segment fusion on the evolution of sagittal balance in children with congenital scoliosis

There is a paucity of data describing sagittal alignment changes in children with congenital scoliosis (CS) treated by hemivertebra (HV) resection. This study aimed to evaluate the effects of posterior HV resection on spine sagittal alignment in children with CS. This is a retrospective analysis of 31 children with CS (mean age at surgery: 49.61 ± 10.21 months; range, 39-72; mean follow-up time: 5.16 ± 1.21 years; range: 3-7) treated at our Institution. Only patients with single thoracic or single lumbar, fully segmented HV managed by posterior HV resection and two segments fusion with four screws and two robs were included. According to the anatomical location of the HV, patients were divided into two groups: thoracic (group A) and lumbar (group B). Thoracic kyphosis (T1-T12; TK) and lumbar lordosis (L1-S1; LL) were measured pre- and postoperatively at 6 months interval. Postoperative TK and LL were 30.3 ± 11.47 and 28.8 ± 9.47, and were 31.98 ± 9.66 and 46.7 ± 11.37 at the last follow-up visit, respectively. The incidence of thoracic hypokyphosis in group B was 53.3%, and it was significantly higher compared to group A (12.5%, P = 0.04). During follow-up, TK changes were comparable between the two groups of patients while LL improved in all patients 6 months after surgery, and continued to improve thereafter. Posterior HV resection and short segment fusion have limited impact on the evolution of TK; in particular, children with lumbar HV were more likely to be hypokyphotic preoperatively, but less likely postoperatively with an increase in LL and a stabilization of TK.

Cervical sagittal alignment in Lenke 1 adolescent idiopathic scoliosis and assessment of its alteration with surgery: a retrospective, multi-centric study

PURPOSE

To document baseline cervical sagittal characteristics in Lenke 1 adolescent idiopathic scoliosis (AIS) patients and assess the alteration in these parameters with surgery.

METHODS

Pre-operative and 2-year postoperative radiographs of 82 Lenke 1 AIS patients recruited from five hospitals were analysed. Selected radiographic parameters capturing regional and global sagittal alignment were measured. Comparison was made between groups based on baseline thoracic kyphosis (TK: TK < 20°, TK ≥ 20°). Pre-operative and postoperative values were compared-the change in each radiographic parameter was correlated with the degree of sagittal and coronal correction.

RESULTS

At baseline, TK was 29.8° ± 16°, cervical lordosis (CL) was - 1° ± 14°, lumbar lordosis (LL) was - 57.1° ± 21°, C2-C7 sagittal vertical axis (SVA) was 16 ± 14 mm and C7-S1 SVA was - 15 ± 28 mm; 44% of patients had cervical kyphosis. Patients with thoracic hypokyphosis had a significantly lower LL and more kyphotic cervical spine compared to those with thoracic normohyperkyphosis. The effect of surgery on TK depended on pre-operative thoracic sagittal alignment-TK increased in patients with thoracic hypokyphosis, but decreased in patients with thoracic normohyperkyphosis. Neither CL nor C2-C7 SVA changed significantly with surgery; 46% of patients still had cervical kyphosis postoperatively.

CONCLUSION

There is a high incidence of cervical kyphosis at baseline in AIS patients-more so in those with pre-operative thoracic hypokyphosis. Unlike TK, CL is not significantly altered with surgery-improvement in CL correlates weakly with sagittal correction of the structural curve.

Does Selective Posterior Correction and Fusion Surgery Influence Cervical Sagittal Alignment in Patient with Lenke Type 5 Adolescent Idiopathic Scoliosis?-A 5-year Follow-up Retrospective Cohort Study

STUDY DESIGN

A retrospective comparative study.

OBJECTIVE

The aim of this study was to examine the changes in cervical sagittal alignment (CSA) following surgical correction in a patient with Lenke type 5 adolescent idiopathic scoliosis (AIS) and evaluate any possible factors influencing postoperative CSA.

SUMMARY OF BACKGROUND DATA

Few studies have assessed the association between CSA and thoracic or lumbar sagittal alignment in AIS patients with major thoracolumbar/lumbar curve who underwent posterior correction and fusion surgery.

METHODS

Sixty-six patients with Lenke type 5 AIS (two males and 64 females, the mean age at surgery of 16.2 years) were included in this study. They were followed up for minimum 5 years after surgery. Multiple linear regression analysis was used to evaluate possible factors influencing the postoperative CSA. To determine the influence of upper end vertebra (UEV) level on postoperative CSA, the subjects were divided into two groups according to UEV level of ≥T9 or ≤T10. The outcome variables were compared between the two groups and analyzed for changes in various spinal sagittal profiles using radiographic outcomes.

RESULTS

Multiple linear regression analysis revealed that preoperative T10-L2 kyphosis and LL were significantly correlated with postoperative C2-7 lordosis. However, CSA did not significantly change at 5 years after surgery. Sub-analysis of the cohort revealed that in the UEV ≥T9 group, the mean thoracic kyphosis significantly increased from 20.3° ± 10.6° to 24.0° ± 8.9° and the mean C2-7 lordosis also significantly increased from -12.5° ± 8.3° to -4.3° ± 10.3° at 5-year postoperatively. SRS-22 outcomes were comparable between the groups.

CONCLUSION

We indicated that the CSA was not influenced by surgical correction in most Lenke type 5 AIS patients. However, in a patient whose UEV was located at T9 or higher levels, CSA was influenced through the changes in thoracic kyphosis following posterior correction surgery.Level of Evidence: 4.

Influence of Chêneau-Brace Therapy on Lumbar and Thoracic Spine and Its Interdependency with Cervical Spine Alignment in Patients with Adolescent Idiopathic Scoliosis (AIS)

Chêneau-brace is an effective therapy tool for treatment in adolescent idiopathic scoliosis (AIS). Data on potential interdependent changes of the sagittal profile including the cervical spine are still sparse. The purpose of this study was to evaluate in-brace changes of the thoracic and lumbar spine and their influence on the pelvis and the cervical spine and apical vertebral rotation was reported. Ninety-three patients with AIS undergoing Chêneau-bracing were included. Patients were stratified by lumbar, thoracic and global spine alignment into normolordotic vs. hyperlordotic or normokyphotic vs. hypokyphotic or anteriorly aligned vs. posteriorly aligned groups. The coronal Cobb angle was significantly decreased in all groups indicating good correction while in-brace therapy. Sagittally, in-brace treatment led to significant flattening of lumbar lordosis (LL) in all stratified groups. Thoracic kyphosis (TK) was significantly flattened in the normokyphotic group, but no TK changes were noticed in the hypokyphotic group. Pelvic tilt (PT) stayed unchanged during the in-brace therapy. Chêneau-brace showed marginal changes in the lower cervical spine but had no influence on the upper cervical spine. The apical vertebral axis in primary and secondary curves was unchanged during the first radiological follow-up. Results from this study contribute to better understanding of initial spine behavior in sagittal and axial plane in the context of bracing.

Global sagittal alignment after surgery of right thoracic idiopathic scoliosis in adolescents and adults with and without thoracic hypokyphosis

This study aimed to characterize global sagittal alignment in adolescent idiopathic scoliosis (AIS) with normal kyphosis (NTK, kyphosis > 10°) and with thoracic hypokyphosis (THK, kyphosis < 10°), before and after posterior spinal fusion, and compare them with asymptomatic controls. 27 AIS girls and young adults with right thoracic curves were included (seventeen with age ≤ 18 years, then age > 21). Biplanar radiographies were acquired at baseline, immediate post-operatively, 1-year and 2-year follow-up, and 3D reconstruction of the spine and pelvis was performed. NTK and THK showed different global sagittal alignment, as well as differences compared to controls. AIS with THK at baseline had higher SVA/SFD (2.0 ± 2.9 vs - 0.4 ± 1.9; P < 0.05) and OD-HA (0.2 ± 1.4° vs - 1.3 ± 1.6°; P < 0.05) than controls, indicating that THK had compensated balance with unusual forward leaning posture. Immediately post-operation, SVA/SFD remained high (1.3 ± 3.0) while OD-HA reversed (- 1.2 ± 1.7°), indicating that THK patients had found partially compensated balance. After 2-yeas, both SVA/SFD (- 1.3 ± 2.1) and OD-HA (- 1.4 ± 0.9°) were normalized. The changes in global sagittal alignment and mechanism of balance are different in AIS with or without THK. As the head plays a critical role on balance during immediate and delayed post-operation, OD-HA can be complementary parameter for assessing global balance during post-operative follow-up of AIS patients with THK.

Very long-term clinical and radiographic outcomes after posterior spinal fusion with pedicular screws for thoracic adolescent idiopathic scoliosis

PURPOSE

To report radiographic and functional outcomes, with an average follow-up of 20 years, of adolescents treated surgically for thoracic idiopathic scoliosis by hybrid construct using only pedicular screws for the distal fixation.

METHODS

We retrospectively reviewed 109 patients. Radiographic data were evaluated on fullspine radiographs (Cobb angle, pelvic incidence, sacral slope, pelvic tilt, thoracic kyphosis, lumbar lordosis). Clinical data were evaluated with ODI, SF-12, SRS-30 and Analog Pain Scale. Disc height and listhesis below the arthrodesis were measured.

RESULTS

We analyzed 90 women and 19 men with a mean age of 16.9 y.o. at surgery. Radiographic data were assessed for 46 patients after 17.4 years. Mean preoperative Cobb angle was 58°, mean correction 40.1% with 5.3° of loss at final FU. Lumbar lordosis and thoracic kyphosis increased significantly at last FU. Degenerative changes below the arthrodesis were reported in 5 cases. Clinical data were assessed for 42 patients after 19.9 years: SRS-30 3.8; ODI 12.3%; SF-12 PCS 48.6 and MCS 46. Low back pain was reported in 69% of cases with low intensity (3.1). The lowest instrumented vertebrae did not influence significantly the functional outcome.

CONCLUSIONS

The correction of thoracic AIS with lumbar or thoracolumbar pedicle screw instrumentation provides good radiological and clinical outcomes at very long term. The reduction in the coronal plane is stable; the HRQoL is quite as good as the general population. The degenerative evolution below remain relatively rare, therefore global sagittal balance is not modified.

A Retrospective Study of Factors Associated with Restoration of Thoracic Kyphosis in 43 Patients with Adolescent Idiopathic Scoliosis with Lenke Type 1 Curvature

BACKGROUND This retrospective study aimed to identify the factors associated with successful surgical correction of thoracic kyphosis (TK) in 43 patients with adolescent idiopathic scoliosis (AIS) with Lenke type 1 curvature, in which the major curve with the largest Cobb angle was mainly in the thoracic region. MATERIAL AND METHODS We collected data from patients with Lenke 1 AIS. The following parameters were measured: Cobb angle, side-bending Cobb angle, cervical lordosis (CL), TK, lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), the sagittal vertical axis (SVA), the center of a C7 plumb line to the center sacral vertical line (C7-CSVL), correction rate, Ponte osteotomy, flexibility, and screw density. Univariate analysis and multivariate logistic regression analyses were performed. RESULTS Among the 43 cases analyzed, the mean postoperative Cobb angle at the last follow-up, C7-CSVL, SVA, CL, TK, LL, PI, SS, and PT were respectively 21.33±9.47°, 10.41±8.45 mm, 19.68±14.33 mm, 16.19±7.45°, 23.12±7.45°, 50.33±11.37°, 49.70±9.83°, 39.42±8.11°, and 10.16±6.63°. Univariate analysis suggested that preoperative TK, preoperative LL, and Ponte osteotomy were statistically significant (P<0.05), and multivariate analysis suggested that preoperative LL and Ponte osteotomy were statistically significant (P<0.05). CONCLUSIONS The results of this study demonstrated that preoperative TK, preoperative LL, and Ponte osteotomy were related factors for maintaining normal TK. Multivariate analysis suggested that preoperative LL and the use of Ponte osteotomy with full-thickness segmental resection of the spinal posterior column resulted in the successful surgical correction of TK in patients with AIS with Lenke type 1 curvature.

Sagittal profile modifications in hybrid versus all screw technique in adolescent idiopathic scoliosis

Aim of the study was to evaluate sagittal parameters modifications, with particular interest in thoracic kyphosis, in patients affected by adolescent idiopathic scoliosis (AIS) comparing hybrid and all-screws technique. From June 2010 to September 2018, 145 patients were enrolled. Evaluation included: Lenke classification, Risser scale, coronal Cobb angle, thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS). Patients were divided in two groups (1 all-screws and 2 hybrid); a further division, in both groups, was done considering preoperative TK values. Descriptive and inferential statistical analysis was conducted. 99 patients were in group 1, 46 in group 2 (mean follow-up 3.7 years). Patients with a normo-kyphotic profile developed a little variation in TK (Δ pre–post = 2.4° versus − 2.0° respectively). Hyper-kyphotic subgroups had a tendency of restoring a good sagittal alignment. Hypo-kyphotic subgroups, patients treated with all-screw implants developed a higher increase in TK mean Cobb angle (Δ pre–post = 10°) than the hybrid subgroup (Δ pre–post = 5.4°) (p = 0.01). All-screws group showed better results in restoring sagittal alignment in all subgroups compared to hybrid groups, especially in hypo-TK subgroup, with the important advantage to give better correction on coronal plane.

Sagittal spinopelvic changes after posterior spinal fusion in adolescent idiopathic scoliosis

PURPOSE

This article examines if longer posterior spinal fusions with instrumentation (PSFI) into the lumbar spine (L3/4) alter spinopelvic parameters compared with selective fusions to T12/L1/L2 in adolescent idiopathic scoliosis (AIS) patients.

METHODS

We analysed radiographs of 84 AIS patients, 58 (69%) females and 26 (31%) males, who underwent PSFI at an mean age of 15 years ± 2.5 years, range 10 years to 21 years, between 1st January 2007 and 31st December 2014. Radiographic parameters were measured pre- and post-operatively at most recent follow-up (range 2 years to 8.2 years): pelvic incidence (PI), lumbar lordosis (LL, L1-S1 and L4-S1), sagittal vertical alignment (SVA), scoliosis angle and proximal junctional kyphosis (PJK). PI-LL was calculated. Data was analysed using t-tests or Wilcoxon rank-sum tests.

RESULTS

In total, 32 patients underwent a selective fusion with lowest instrumented vertebra (LIV) T12-L2, and 52 patients underwent a fusion with LIV L3-L4. In both groups, scoliosis angle was significantly corrected at follow-up (p < 0.005).Pre-operatively, both groups had similar LL (L1-S1) and PI-LL. Post-operatively, LL increased in the L3-4 fusion group (p < 0.005) but did not change in the selective fusion group (p = 0.116). This change in LL in the L3-4 fusion group affected the post-operative PI-LL (T12-L2 fusion -4.9° versus L3-4 fusion -13.6°, p = 0.002). No differences were seen in PI, SVA or LL L4-S1 between groups. Radiographic PJK occurred in seven of the L3-4 patients with and without PJK (noPJK -8.8° versus PJK -25.8°, p = 0.026).

CONCLUSIONS

In patients who underwent a fusion ending at L3 or L4, LL was increased. This altered the PI-LL relationship, and appeared to increase the risk of PJK.

LEVEL OF EVIDENCE

III.

Cervical Sagittal Alignment: Literature Review and Future Directions

Cervical alignment as a concept has come to the forefront for spine deformity research in the last decade. Studies on cervical sagittal alignment started from normative data, and expanded into correlation with global sagittal balance, prognosis of various conditions, outcomes of surgery, definition and classification of cervical deformity, and prediction of targets for ideal cervical reconstruction. Despite the recent robust research efforts, the definition of normal cervical sagittal alignment and cervical spine deformity continues to elude us. Further, many studies continue to view cervical alignment as a continuation of thoracolumbar deformity and do not take into account biomechanical features unique to the cervical spine that may influence cervical alignment, such as the importance of musculature connecting cranium-cervical-thoracic spine and upper extremities. In this article, we aim to summarize the relevant literature on cervical sagittal alignment, discuss key results, and list potential future direction for research using the '5W1H' framework; "WHO" are related?, "WHY" important?, "WHAT" to evaluate and "WHAT" is normal?, "HOW" to evaluate?, "WHEN" to apply sagittal balance?, and "WHERE" to go in the future?

Complication profile associated with S1 pedicle subtraction osteotomy compared with 3-column osteotomies at other thoracolumbar levels for adult spinal deformity: series of 405 patients with 9 S1 osteotomies

OBJECTIVE

There is an increased recognition of disproportional lumbar lordosis (LL) and artificially high pelvic incidence (PI) as a cause for positive sagittal imbalance and spinal pelvic mismatch. For such cases, a sacral pedicle subtraction osteotomy (PSO) may be indicated, although its morbidity is not well described. In this study, the authors evaluate the specific complication risks associated with S1 PSO.

METHODS

A retrospective review of all adult spinal deformity patients who underwent a 3-column osteotomy (3CO) for thoracolumbar deformity from 2006 to 2019 was performed. Demographic, clinical baseline, and radiographic parameters were recorded. The primary outcome of interest was perioperative complications (surgical, neurological, and medical). Secondary outcomes of interest included case length, blood loss, and length of stay. Multivariate analysis was used to assess the risk of S1 PSO compared with 3CO at other levels.

RESULTS

A total of 405 patients underwent 3CO in the following locations: thoracic (n = 55), L1 (n = 25), L2 (n = 29), L3 (n = 141), L4 (n = 129), L5 (n = 17), and S1 (n = 9). After S1 PSO, there were significant improvements in the sagittal vertical axis (14.8 cm vs 6.7 cm, p = 0.004) and PI-LL mismatch (31.7° vs 9.6°, p = 0.025) due to decreased PI (80.3° vs 65.9°, p = 0.006). LL remained unchanged (48.7° vs 57.8°, p = 0.360). The overall complication rate was 27.4%; the surgical, neurological, and medical complication rates were 7.7%, 6.2%, and 20.0%, respectively. S1 PSO was associated with significantly higher rates of overall complications: thoracic (29.1%), L1 (32.0%), L2 (31.0%), L3 (19.9%), L4 (32.6%), L5 (11.8%), and S1 (66.7%) (p = 0.018). Similarly, an S1 PSO was associated with significantly higher rates of surgical (thoracic [9.1%], L1 [4.0%], L2 [6.9%], L3 [5.7%], L4 [10.9%], L5 [5.9%], and S1 [44.4%], p = 0.006) and neurological (thoracic [9.1%], L1 [0.0%], L2 [6.9%], L3 [2.8%], L4 [7.0%], L5 [5.9%], and S1 [44.4%], p < 0.001) complications. On multivariate analysis, S1 PSO was independently associated with higher odds of overall (OR 7.93, p = 0.013), surgical (OR 20.66, p = 0.010), and neurological (OR 14.75, p = 0.007) complications.

CONCLUSIONS

S1 PSO is a powerful technique for correction of rigid sagittal imbalance due to an artificially elevated PI in patients with rigid high-grade spondylolisthesis and chronic sacral fractures. However, the technique and intraoperative corrective maneuvers are challenging and associated with high surgical and neurological complications. Additional investigations into the learning curve associated with S1 PSO and complication prevention are needed.

Analysis of Lumbar Sagittal Curvature in Spinal Decompression and Fusion for Lumbar Spinal Stenosis Patients under Roussouly Classification

To evaluate the clinical significance of spinal decompression and fusion for lumbar spinal stenosis in old patients under Roussouly classification, 160 old patients (>60 year old) with lumbar spinal stenosis underwent spinal decompression, and fusion were retrospectively studied. According to Roussouly classification, patients were divided into 4 groups, in which Roussouly types I, II, and IV were the nonstandard group and Roussouly type III was the standard group. Visual analog scale (waist, leg) and Oswestry disability index (ODI) scores were recorded before operation and at the final follow-up. All patients improved the sagittal curvature: for patients in Roussouly types I and II, there were statistically significant differences in terms of postoperative global lordosis (GL), global kyphosis (GK), sacral slope (SS), sagittal vertical axis (SVA), and pelvic tilt (PT) compared with that before surgery (all P < 0.001); patients in Roussouly type IV obtained similar results with type III after surgery. The four groups showed significant improvement in ODI and VAS scores at final follow-up (all P < 0.001). After regrouping at the final follow-up, the proportion of the standard type (Roussouly type III) patients was increased compared with preoperative. In conclusion, Roussouly classification has important guiding significance in spinal decompression and fusion for old patients (>60 years) with lumbar spinal stenosis.

Essential lordosis revisited

AIMS

Significant correction of an adolescent idiopathic scoliosis in the coronal plane through a posterior approach is associated with hypokyphosis. Factors such as the magnitude of the preoperative coronal curve, the use of hooks, number of levels fused, preoperative kyphosis, screw density, and rod type have all been implicated. Maintaining the normal thoracic kyphosis is important as hypokyphosis is associated with proximal junctional failure (PJF) and early onset degeneration of the spine. The aim of this study was to determine if coronal correction per se was the most relevant factor in generating hypokyphosis.

METHODS

A total of 95 patients (87% female) with a median age of 14 years were included in our study. Pre- and postoperative radiographs were measured and the operative data including upper instrumented vertebra (UIV), lower instrumented vertebra (LIV), metal density, and thoracic flexibility noted. Further analysis of the post-surgical coronal outcome (group 1 < 60% correction and group 2 ≥ 60%) were studied for their association with the postoperative kyphosis in the sagittal plane using univariate and multivariate logistic regression.

RESULTS

Of the 95 patients, 71.6% (68) had a thoracic correction of > 60%. Most (97.8%) had metal density < 80%, while thoracic flexibility > 50% was found in 30.5% (29). Preoperative hypokyphosis (< 20°) was present in 25.3%. A postoperative thoracic hypokyphosis was four times more likely to occur in patients with thoracic correction ≥ 60% (odds ratio (OR) 4.08; p = 0.005), after adjusting for confounding variables. This association was not affected by metal density, thoracic flexibility, LIV, UIV, age, or sex.

CONCLUSION

Our study supports the 'essential lordosis' hypothesis of Roaf and Dickson, i.e. with a greater ability to translate the apical vertebra towards the midline, there is a commensurate lengthening of the anterior column due to the vertebral wedging. Cite this article: Bone Joint J 2020;102-B(4):513-518.

Changes in the Position of the Junctional Vertebrae After Posterior Spinal Fusion in Adolescent Idiopathic Scoliosis: Implication in Risk Assessment of Proximal Junctional Kyphosis Development

BACKGROUND

The development of proximal junctional kyphosis (PJK) after posterior spinal fusion in adolescent idiopathic scoliosis is a major problem. Changes in the global sagittal parameters as they relate to PJK have been reported after surgery, however, the relationships between the changes in the upper-instrumented vertebra (UIV) during and after surgery as they relate to development of PJK have not been quantified. We hypothesize that the compensatory changes in the unfused segments of the spine over time are correlated with the surgically induced changes in the UIV position.

METHODS

Sixty adolescent idiopathic scoliosis patients (with at least 1-year follow-up) who underwent posterior spinal surgery were included retrospectively. Global spinal parameters were calculated using 3-dimensional models of the spine, additional parameters [proximal junctional kyphosis angle (PJKA), cervical lordosis angle] were measured manually before surgery and at 3 postoperative follow-ups. The 3-dimensional position of the vertebral body centroids was calculated for T1, UIV, and lower-instrumented vertebra at all timepoints. The sagittal position of T1, UIV, and lower-instrumented vertebra were correlated to the cervical lordosis, PJKA, lumbar lordosis, and pelvic tilt.

RESULTS

The position of T1 and UIV were significantly more anterior at first erect for patients who developed PJK. The posterior shift of UIV at the most recent follow-up as compared with the preoperative position was significant in both the PJK and non-PJK cohort. A larger anterior shift in UIV at first erect correlated with a larger T1 and UIV posterior shift at the most recent follow-up. At the most recent follow-up, a more posterior position of the UIV correlated with a larger angle of PJKA (P<0.05).

CONCLUSION

Both a larger anterior shift of UIV between preoperative and first erect and a more posterior position of UIV at the most recent follow-up was correlated with a higher PJKA. A larger anterior shift in the position of the UIV after surgery was associated with a higher posterior shift of UIV at the last follow-up. The surgically induced changes in the UIV are an important parameter associated with the development of PJK.

LEVEL OF EVIDENCE

Level IV.

Analysis of the Relationship Between Modic Change and Spinopelvic Parameters in the Sagittal Plane

Background

This study explored relationship between Modic change and spinopelvic parameters in the sagittal plane.

Material/Methods

We divided 80 patients into 4 groups: 60 subjects diagnosed with Modic changes (MC) were enrolled in the MC groups (MC1, MC2, and MC3) with each MC type consisting of 20 subjects, and 60 healthy subjects were enrolled in the control group. Spinopelvic parameters in the sagittal plane were calculated to assess their associations with MC. Multivariate logistic regression was used to explore possible risk factors for MC.

Results

PI and LL in the MC groups were significant smaller than in the control group (p<0.05). PI, SS, and PT were significantly correlated with LL with a correlation coefficient of 0.75_PI, 0.71_SS and 0.69_PT (p<0.05). Multivariate logistic regression of the significant variables showed that PI (less than 43.2°) is an independent significant risk factor for MC. ROC analysis showed that moderate diagnostic value was obtained for the significant variable, with an area under the curve (AUC) of 0.80 (p>0.05).

Conclusions

We concluded that PI is risk factor for MC, and smaller PI is associated with higher incidence of MC.

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.

Reciprocal Change in Sagittal Profiles After Adolescent Idiopathic Scoliosis Surgery With Segmental Pedicle Screw Construct: A Full-body X-ray Analysis

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

This radiographic analysis using a full-body x-ray evaluated the ways in which the sagittal profiles of the unfused spinal segments, pelvic, and lower extremities spontaneously change after adolescent idiopathic scoliosis (AIS) surgery with segmental pedicle screw constructs.

SUMMARY OF BACKGROUND DATA

Reciprocal lordotic changes in unfused spinal segments after corrective surgery for AIS have been reported. However, a full-body analysis has not been studied.

METHODS

The sagittal profiles of 51 (age ≤18) patients with AIS undergoing corrective surgery with segmental pedicle screw constructs were investigated. Patients were divided into two groups: group T; selective thoracic fusion and group L; fusion to the low lumbar spine. They were further subcategorized according to preoperative thoracic kyphosis (TK: T5-12): hypokyphotic (TK <20°) and normohyperkyphotic (TK >20°) groups. The postoperative change in the sagittal parameters and the correlation between the instrumented thoracic alignment change (ΔT2-12) and reciprocal changes of unfused segments were analyzed.

RESULTS

At baseline, the entire cohort had a relatively hypokyphotic thoracic spine (TK: 25.5° ± 13.7°), low T1 slope (13.6° ± 7.7°), and kyphotic cervical spine (C2-7 lordosis: 7.7° ± 13.1°). The lower extremities were in neutral alignment overall. Postoperatively, the cervical alignment changed significantly lordotic (average -13.4° increased lordosis) after the adequate preservation of TK (average 17.8° increased kyphosis) in the hypokyphotic group T. Linear correlations were observed between ΔT2-12 and spontaneous reciprocal changes in C2-7 lordosis, lumbar lordosis, and knee flexion angle in group T.

CONCLUSION

The sagittal profiles of patients with AIS can significantly change after adequate restoration of TK which averaged 17.8°, particularly in the cervical spine. Lordotic reciprocal change in the cervical spine as well as increase in lumbar lordosis can occur in a linear correlation after adequate restoration of TK. There were no significant changes that occurred in the pelvis or lower extremities after AIS corrective surgery.

LEVEL OF EVIDENCE

4.

Evaluation of a new sagittal classification system in adolescent idiopathic scoliosis

PURPOSE

The purpose of the present study was to validate a new spinal sagittal classification.

METHODS

We retrospectively included 105 consecutive AIS patients who underwent posterior spinal fusion. Preoperative long-standing EOS radiographs were available on all patients. Patients were classified according to the four suggested sagittal patterns: type 1, 2a, 2b or 3. Several predetermined sagittal parameters were compared between the groups.

RESULTS

The mean preoperative Cobb angle was 64° ± 12°, and 73% of the patients were female. Of 105 patients, 51 were type 1, 14 were type 2a, one was type 2b and 39 were type 3. The distribution of the four sagittal patterns was significantly different compared with the original publication (p < 0.05). However, the two study populations were comparable in terms of Lenke and Roussouly types (p = 0.49 and 0.47, respectively). In our study population, the sagittal groups differed significantly in terms of thoracic kyphosis, length of thoracic and lumbar curves, lumbar lordosis, thoracic slope, C7 slope, pelvic incidence and sacral slope (p < 0.05).

CONCLUSION

The distribution of the four sagittal patterns varies between AIS cohorts. Type 2b was rare, which limits the clinical applicability. Contrary to the original publication, we found that the spinopelvic parameters lumbar lordosis, pelvic incidence and sacral slope were significantly different between the Abelin-Genevois types. Hence, the corrective surgical strategy may need to incorporate these spinopelvic parameters to achieve a balanced spine requiring a minimum of energy expenditure. These slides can be retrieved under Electronic Supplementary Material.

Defining criteria for optimal lumbar curve correction following the selective thoracic fusion surgery in Lenke 1 adolescent idiopathic scoliosis: developing a decision tree

OBJECTIVE

The aim of this study was to identify the range of optimal versus suboptimal rates of spontaneous lumbar Cobb correction (SLCC%) and the factors predicting such outcomes in a cohort of Lenke 1 adolescent idiopathic scoliosis (AIS) after posterior spinal fusion surgery.

METHODS

Seventy-one consecutive Lenke1 B and C AIS patients with a fusion level to L1 and higher with two-year follow-up were included. Thoracic kyphosis (T1-T4 and T4-T12 TK), lumbar lordosis (L1-S1 LL), thoracic and lumbar Cobb angles, thoracic and lumbar apical vertebral rotations and translations (AVR and AVT), pelvic incidence, sacral slope, and sagittal and frontal balances were measured at preoperative, early postoperative, and two-year follow-up. The SLCC% was calculated between preoperative and two-year follow-up. A clustering analysis determined the subgroups of patients with significantly higher and lower (optimal versus suboptimal) rate of SLCC% in the cohort at two-year follow-up. The cutoff values of the preoperative and early postoperative radiographic parameters that significantly predicted the optimal and suboptimal SLCC% were determined using a decision tree.

RESULTS

The averages of the optimal versus suboptimal range of SLCC% in the cohort were 72% [55%, 105%] versus 39% [- 7%, 42%]. Preoperative and early postoperative spinal parameters predicted the optimal versus suboptimal SLCC% with an accuracy of 82%, 95%CI [0.73-0.94]. Preoperative AVT_Lumbar < 10 mm was a predictor of optimal SLCC%. In patients with a preoperative AVT_Lumbar > 10 mm, early postoperative T4-T12 TK < 24° (but not less than 17°) accompanied by - 5° < AVR_Thoracic < 5° were the main predictors of optimal SLCC% in our cohort.

CONCLUSION

Quantitative clustering of the SLCC% into optimal and suboptimal groups allowed identifying the cutoff values of preoperative (AVT_Lumbar) and early postoperative (T4-T12 TK and AVR_Thoracic) spinal parameters that can predict the optimal range of SLCC% at two-year postoperative in our cohort of Lenke 1 AIS.

LEVEL OF EVIDENCE

IV.

Bone Remodeling and Disc Morphology in the Distal Unfused Spine After Spinal Fusion in Adolescent Idiopathic Scoliosis

BACKGROUND

Morphologic changes in the vertebral body in adolescent idiopathic scoliosis (AIS) have been associated with curve development and progression. Yet, after an AIS spinal surgery, the impact of the global and local spinal realignment on the vertebral body and intervertebral disc morphologic changes, particularly in the distal unfused spine, have not been determined.

QUESTIONS/PURPOSES

To determine the changes in the unfused lumbar vertebrae and disc morphology two years after spinal fusion in AIS patients undergoing selective thoracic fusion (STF).

PATIENTS AND METHODS

A total of 58 patients with Lenke type 1 AIS who underwent STF with a minimum two-year follow-up and 20 nonscoliotic adolescents were included. Biplanar stereoradiography of the spine at preoperative, early postoperative, and two-year follow-up were used to generate 3D models of the spine. Lumbar spine vertebral and intervertebral heights (anterior, posterior, left, and right) and the degree of wedging in the frontal and sagittal plane were calculated in the local coordinate system of the vertebral bodies. The morphology of vertebrae and discs were compared between the pre- and postoperative visits of AIS patients and nonscoliotic controls.

RESULTS

Lumbar lordosis was not statistically different between the pre- and post-operative AIS and controls, p > .05. The contribution of the lumbar vertebral bodies and discs' sagittal wedging to the total L1-L5 lordosis were 20% and 80%, respectively, for nonscoliotic controls and 61% and 39%, respectively, for AIS patients at two-year follow-up. The decrease in the anterior and left heights of the disc between the preoperative and two-year follow-up was significant, p < .05.

CONCLUSION

Patients undergoing STF for Lenke 1 AIS are able to achieve normal lumbar lordosis after surgery but seem to regain their sagittal alignment by morphologic changes in the disc more so than the vertebral body. A larger contribution of the vertebral sagittal wedging to the total lumbar lordosis at two years post STF was observed when these variables were compared to the nonscoliotic adolescents.

LEVEL OF EVIDENCE

Level IV.

Characterization of trunk motion in adolescents with right thoracic idiopathic scoliosis

BACKGROUND

Although standard radiography is currently used for deformity assessment in AIS patients, it is performed in a constrained position and probably not reflective of spinal balance during daily-life activities. Our main objective was to compare trunk motion in Lenke 1 and 2 AIS patients to healthy volunteers, using gait analysis.

MATERIAL AND METHODS

Lenke 1 or 2 AIS patients planned for surgery were included. The day before surgery, they underwent radiographic evaluation and gait analysis. Among the gait parameters, sagittal vertical axis (Dyn-SVA), shoulder line rotation (Dyn-SL rotation), pelvis rotation (Dyn-P rotation) and acromion pelvis angle (Dyn-APA) were measured. AIS patients were compared to 25 asymptomatic controls.

RESULTS

A total of 57 patients were included in the study, with a mean Cobb angle of 55.4°. AIS patients had a lower Dyn-SVA when compared to controls (47.0 vs. 62.9 mm, p = 0.012). Dyn-APA and Dyn-SL rotation were negative in AIS patients, meaning that shoulder line was rotated towards the left (- 6.4 vs. 7.8° and - 7.5 vs. - 0.4°, p<0.001, respectively). On the other hand, Dyn-P rotation was positive, meaning that pelvis was rotated towards the right side during gait (1.1 vs. - 0.5, p = 0.026).

DISCUSSION

This is one of the largest series of gait analysis in AIS patients. We demonstrated that AIS patients have an abnormal gait pattern, with a decreased anterior tilt of the trunk and transverse plane abnormalities. We found that gait deviation was not related to radiographic measurements, pointing out that dynamic assessment provides new data about spinal posture. These slides can be retrieved under Electronic Supplementary Material.

Quasi-automatic early detection of progressive idiopathic scoliosis from biplanar radiography: a preliminary validation

PURPOSE

To validate the predictive power and reliability of a novel quasi-automatic method to calculate the severity index of adolescent idiopathic scoliosis (AIS).

METHODS

Fifty-five AIS patients were prospectively included (age 10-15, Cobb 16° ± 4°). Patients underwent low-dose biplanar X-rays, and a novel fast method for 3D reconstruction of the spine was performed. They were followed until skeletal maturity (stable patients) or brace prescription (progressive patients). The severity index was calculated at the first examination, based on 3D parameters of the scoliotic curve, and it was compared with the patient's final outcome (progressive or stable). Three operators have repeated the 3D reconstruction twice for a subset of 30 patients to assess reproducibility (through Cohen's kappa and intra-class correlation coefficient).

RESULTS

Eighty-five percentage of the patients were correctly classified as stable or progressive by the severity index, with a sensitivity of 92% and specificity of 74%. Substantial intra-operator agreement and good inter-operator agreement were observed, with 80% of the progressive patients correctly detected at the first examination. The novel severity index assessment took less than 4 min of operator time.

CONCLUSIONS

The fast and semiautomatic method for 3D reconstruction developed in this work allowed for a fast and reliable calculation of the severity index. The method is fast and user friendly. Once extensively validated, this severity index could allow very early initiation of conservative treatment for progressive patients, thus increasing treatment efficacy and therefore reducing the need for corrective surgery. These slides can be retrieved under Electronic Supplementary Material.

Management of Adolescent Idiopathic Scoliosis: Institutional Experience, Integration into Neurosurgical Practice, and Impact on Resident Training

OBJECTIVE

Management of adolescent idiopathic scoliosis (AIS) in neurosurgery residency training may have a significant impact on resident experience, even though few trainees are likely to pursue careers in the field of AIS. The impact of this exposure on resident knowledge in adult spinal disease management is the subject of our retrospective analysis.

METHODS

An analysis was performed of all adolescent patients undergoing surgical correction of spinal deformity between 2006 and 2016. Patient characteristics, including age at operation, Cobb angles, length of stay, operative time, blood loss, and complications, were collected. Objective benchmarks were created for resident education in the management of AIS. A survey was sent to the last 7 years of graduates to assess the impact of exposure to AIS during neurosurgery training on their current practice.

RESULTS

Nine male and 37 female patients ages 11 to 22 years were identified. Neurosurgical residents assisted in all procedures without fellows or surgical assistants. Average operative time was 336 minutes (range, 215-575 minutes), and blood loss per procedure was 603 mL (range, 200-4000 mL). The average Cobb angle correction was 72.2% (range, 35.3%-90.9%). Zero of the past 7 graduates currently treat AIS surgically. All 7 graduates agreed that exposure to AIS during residency enhanced their knowledge of adult spinal disease management.

CONCLUSIONS

Treatment of AIS by surgeons with specialized training can be effective and safe. Resident exposure to these patients enhances their understanding of spinal biomechanics and deformity correction, which is applicable to treating AIS and adult spinal deformity.

Impact of Adult Scoliosis on Roussouly Sagittal Shape Classification

STUDY DESIGN

A retrospective analysis of data collected prospectively in an adult spine deformity multicenter database.

OBJECTIVE

The aim of this study was to determine the impact of adult scoliosis (AS) on the type of Roussouly sagittal shape in terms of classification applicability, scoliosis modification of a patient theoretical sagittal shape, and coronal-sagittal deformity associations.

SUMMARY OF BACKGROUND DATA

Roussouly described a four-type sagittal shape classification in healthy individuals, which has been also applied to patients with degenerative spinal disease. However, it remains uncertain if its principles can be applied to AS patients.

METHODS

AS patients recorded in a prospective multicenter database of adult spinal deformity were included. Preoperative sagittal radiographs were analyzed using the KEOPS software to measure pelvic parameters, global sagittal alignment, and the various criteria used for the Roussouly classification. The different sagittal shape types were compared using the Chi-square and McNemars tests, and analysis of variance with Bonferroni correction.

RESULTS

The classification was applicable to all of the 190 analyzed AS patients. In addition to Roussouly criteria, two parameters helped differentiate the different shapes: T10-L2 angle (24° ± 19 type-1; 14° ± 15 type-2; 3° ± 15 type-3; 0.4° ± 14 type-4; P < 0.001), and lordosis distribution index (90% ± 17 type-1; 83% ± 16 type-2; 73% ± 21 type-3; 63% ± 16 type-4; P < 0.001). AS changed the theoretical shape in 34% of the patients (P < 0.001). Curve etiology and curve pattern were not associated with any particular type of sagittal shape (P > 0.05). Type-1 was associated with older patients (P = 0.02), degenerative curves (P = 0.02), and greater PI-LL mismatch (P = 0.012). Types 3 to 4 were associated with younger age and idiopathic etiology (P < 0.001).

CONCLUSION

Roussouly four-type sagittal shape classification could be applied to AS patients. AS modified the theoretical type in one of every three patients. No particular association was found between the sagittal types and specific coronal deformities. Sagittal shape recognition in patients with AS will help restore the appropriate theoretical shape through surgery, which can eventually lead to better surgical outcomesLevel of Evidence: 2.

Sagittal Alignment After Surgical Treatment of Adolescent Idiopathic Scoliosis-Application of the Roussouly Classification

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To investigate spinopelvic alignment and spine shape in patients surgically treated for adolescent idiopathic scoliosis (AIS) and to assess the distribution and clinical applicability of the Roussouly classification.

SUMMARY OF BACKGROUND DATA

How spinopelvic alignment is affected in AIS patients is not well established. Roussouly et al. proposed a classification based on the sagittal spinal profile and spinopelvic alignment that may have clinical utility in these patients.

METHODS

A consecutive cohort of 134 surgically treated AIS patients were included. Whole-spine standing lateral radiographs were analyzed preoperatively, one-week postoperatively and at two-year follow-up. Patients were categorized using the modified Roussouly classification and analyzed for sagittal alignment.

RESULTS

Postoperatively, global thoracic kyphosis (TK) decreased by 2.6° and lumbar lordosis (LL) decreased by 6.2°(p ≤ .012) while Pelvic tilt (PT) increased 1.4° (p = .024). At two-year follow-up, TK and LL had returned to preoperative values (p ≥ .346) while PT had decreased from preoperative 9.7 ± 7.6° to 7.0 ± 7.5° (p > .001). Proximal junctional angle increased from 8.4 ± 5.0° preoperatively to 12.8 ± 8.9 (p < .001). Preoperatively, Roussouly curve types were distributed equally apart from a lower rate of type 1 (12%). At final follow-up, 30% were categorised as type 3 with pelvic anteversion which is considerably higher than the normal adolescent population. Only three patients were type 1 at the final follow-up. Overall, we found a high rate of proximal junctional kyphosis (16%), PI-LL mismatch (60%) and pelvic anteversion (38%). In preoperative type 1 patients, the rate was 50%, 82% and 64%, respectively.

CONCLUSION

We found that immediate postoperative changes in lordosis and kyphosis were reversed at final follow-up and found evidence of proximal junctional kyphosation and pelvic anteversion as the main compensatory mechanisms. Poor sagittal alignment was frequent in type 1 curves, and surgical treatment may need to be individualized according to the sagittal profile.

LEVEL OF EVIDENCE

III.

Cervical spine alignment following surgery for adolescent idiopathic scoliosis (AIS): a pre-to-post analysis of 81 patients

Background

Several studies have emphasized the importance of restoring thoracic kyphosis (TK) in the setting of AIS, but very few have discussed changes in cervical spine alignment following surgery. Aim of this study was to evaluate reciprocal cervical alignment change after modification of global and regional thoracolumbar alignment with surgery in the setting of adolescent idiopathic scoliosis (AIS).

Methods

Baseline and 2-yrs follow-up radiographs of AIS patients (n = 81) were analysed measuring cervical parameters (upper cervical: C2-C0, McGregor Slope; lower cervical: C2-C7, C2-C7 sagittal vertical axis (SVA), C2-T3, C2-T3SVA, C2-T1Harrison (C2-T1Ha), T1 Slope (T1S)), thoracic, lumbar, pelvic and global alignment parameters. Post-operatively, patients were grouped twice; based on changes in TK and SVA. Cervical alignment was compared between groups. Pearson correlation was conducted to examine the relationship between changes in TK, SVA, and cervical alignment.

Results

Stratification by change in TK, revealed significant alteration of lower cervical alignment T1S [p < 0.001]), C2-T3 [p = 0.019], C2-T1Ha [p = 0.043]), but there was no reciprocal change in the upper cervical spine. Stratification by SVA revealed a significant coexisting change in the lower cervical spine (T1S [p < 0.001], C2-C7SVA [p = 0.034], C2-T3 [p = 0.023], C2-T3SVA [p = 0.001]). SVA change was not associated to a change in the upper cervical spine. The correlation analysis showed that with a post-operative increase in TK, the cervical spine became more lordotic. Changes in TK were significantly correlated with: ΔT1S, ΔC2-C7, ΔC2-T3, and ΔC2-T3SVA. Similarly, increased cervical kyphosis was found when SVA was decreased post-operatively. Furthermore, there was a significant correlation between change of SVA and both ΔC2-T3 and ΔC2-T3SVA.

Conclusions

In surgically treated AIS patients, changes in global and regional alignment of the thoracolumbar and cervical spinal segments exhibit interdependence. Thus, surgical planning with regard to sagittal deformity in AIS patients should account for the post-operative impact on cervical alignment.

Coronal Balance vs. Sagittal Profile in Adolescent Idiopathic Scoliosis, Are They Correlated?

Background: Clinical evaluation of the postural balance in adolescent idiopathic scoliosis has been evaluated by coronal and sagittal parameters. The relationship between coronal and sagittal parameters has not been fully studied in adolescent idiopathic scoliosis. Objective: This study aimed to evaluate the relationship between coronal and sagittal parameters in idiopathic scoliosis. Methods: One hundred and three patients of Adolescent Idiopathic Scoliosis (AIS) were recruited. Radiographs were evaluated for the following spine and pelvic measurements. Coronal parameters including thoracic Cobb angle (TC), lumbar Cobb angle (LC), global coronal balance (GCB), apical translation of the major curve (AT), and coronal pelvic tilt (CPT) were analyzed. Sagittal parameters including thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) were analyzed. A canonical correlation analysis was performed between all of the coronal parameters and sagittal parameters. Results: One hundred and three patients were recruited (male 15, female 88; aged 12.5 ± 1.5 years). Compared with the published age-matched normal population, TK, PI, LL, and SS were not statistically different in the normal group. However, PT was significantly increased in patent groups (P = 0.003). Canonical correlation analysis showed strong correlation between coronal parameters and sagittal parameters, F _{(20, 313)} = 2.44, p = 0.001. SVA was not correlated with any coronal parameter. Conclusions: Children with AIS showed an increased pelvic tilt sign. In this study, TC, LC, GCB, AT, CPT, TK, LL, SVA, PI, PT, and SS contributed to the postural balance. In AIS, coronal balance is contributed to sagittal balance.

Sagittal Spinopelvic Alignment After Posterior Spinal Fusion in Adolescent Idiopathic Scoliosis: A Systematic Review and Meta-analysis

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVE

The aim of this study was to determine the differences in the sagittal spinopelvic parameters between the nonscoliotic controls, preoperative, and different time points postoperative in Lenke 1 and 5 adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

The postoperative changes in the sagittal profile of Lenke 1 and 5 AIS at varying time points after posterior spinal fusion (PSF) has not been rigorously demonstrated; studies performed have had conflicting results.

METHODS

Sagittal spinal and pelvic parameters, T5-T12 thoracic kyphosis (TK), L1-S1 lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), and sagittal vertical axis (SVA), for Lenke 1 and 5 preoperatively, at immediate, less than 2-year, and more than 2-year postoperatively, and for nonscoliotic adolescents were searched. Differences in the sagittal spinopelvic parameters between preoperative and the follow-ups and between the nonscoliotic and pre- and postoperative AIS subtypes were calculated through meta-analysis.

RESULTS

A total of 22 studies on Lenke1 (1229 patients), 13 studies on Lenke5 (437 patients), and 18 studies on controls (1636 patients) were reviewed. Among all the measured variables, only PI in Lenke1 was significantly different between the final follow-up and controls, P < 0.05. In Lenke 1, SVA was significantly more anterior at the immediate postoperative than preoperative, but continued moving posteriorly up to 2-year postoperative resulting in no significant difference in the SVA position between the final follow-up and preoperative, P > 0.05. In Lenke 5, SVA was significantly more posterior at the immediate postoperative and more anterior at the final follow-up than the preoperative measurements, p < 0.05.

CONCLUSIONS

Continuous changes in the sagittal spinal parameters should be expected after PSF. Normalization of the sagittal spinal parameters appears to be the rule after PSF, and watchful waiting appears to be appropriate in this population when viewing the lateral X-ray postoperatively.

LEVEL OF EVIDENCE

4.