Cervical sagittal alignment in patients with adolescent idiopathic scoliosis: is it corrected by surgery?

No short-term clinical improvement and mean 6° of thoracic kyphosis correction using limited-level Ponte osteotomy near T7 for Lenke type 1 and 2 adolescent idiopathic scoliosis: a preliminary study

This study was a retrospective single surgeon case series approved by institutional review board and showed the efficacy of limited Ponte osteotomy at T6/7, 7/8 and 8/9 (limited-PO) in the sagittal plane for patients with Lenke type 1 and 2 adolescent idiopathic scoliosis (AIS). A total of 37 consecutive patients [7 males and 30 females; average age 16.0 ± 2.5 (range: 12-21)] over a 4-year period with posterior corrective fusion surgery were included. Initially, 18 patients were operated on without limited-PO [P(-)-group]. Midway in the series, the senior author switched to the limited-PO [P(+)-group]. The limited-PO has been performed to form the apex of thoracic kyphosis at the T7 level, together with the restoration of thoracic kyphosis. The mean amount of the correction angle of thoracic kyphosis was more in the P(+)-than in P(-)-group (13.8 ± 9.6° vs. 7.8 ± 8.0°, P  = 0.046) at 1-year after surgery. Cervical lordosis was spontaneously corrected more in P(+)-than in P(-)-group. The apex of thoracic kyphosis was controlled around the T7 level postoperatively in most cases (18/19 cases). There was no significant difference between the two groups in terms of blood loss and operative time per level, or Scoliosis Research Society-22 domain scores. Limited-PO contributed to the restoration of the whole spinal sagittal alignment for Lenke type 1 and 2 AIS; however, in this preliminary study, the clinical improvement was unclear at least in the short term, because the kyphosis angle obtained by limited-PO was only approximately 6°.

Reciprocal Change of Cervical Spine after Posterior Spinal Fusion for Lenke Type 1 and 2 Adolescent Idiopathic Scoliosis

Reciprocal sagittal alignment changes after adolescent idiopathic scoliosis (AIS) posterior corrective surgery have been reported in the cervical spine, but the evidence is not yet sufficient. Furthermore, much remains unknown about the effects of cervical kyphosis on clinical outcomes in AIS. Forty-five consecutive patients (4 males and 41 females) with AIS and Lenke type 1 or 2 curves underwent a posterior spinal fusion, and a minimum of 24-month follow-up was collected from our prospective database. We investigated radiographic parameters and SRS-22r. Before surgery, cervical kyphosis (cervical lordosis < 0°) was present in 89% and cervical hyperkyphosis (cervical lordosis < -10°) in 60%. There were no significant differences in age, sex, or Lenke type between the hyperkyphosis and the non-hyperkyphosis groups. Although cervical lordosis increased significantly after surgery, cervical kyphosis was observed in 73% of patients 2 years after surgery. We found a significant correlation between Δthoracic kyphosis (TK) and Δcervical lordosis. Preoperative cervical kyphosis, ΔT1 slope, and ΔTK were independently associated factors for postoperative cervical hyperkyphosis. The cervical hyperkyphosis group had significantly lower SRS-22r domains. In AIS corrective surgery, restoring TK leading to a gain of T1 slope may lead to an improvement of cervical sagittal alignment. Remaining cervical hyperkyphosis after AIS surgery may affect clinical outcomes.

Cervical Spinal Cord Compression in Adult Scoliosis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

The aim was to examine cervical spinal cord compression (SCC) in adult scoliosis and clarify the prevalence of and risk factors for cervical SCC.

METHODS

This study included 270 adult scoliosis patients and 1211 healthy volunteers. Cervical SCC was evaluated on cervical magnetic resonance imaging (MRI). The rates of SCC for those with adult scoliosis and the healthy volunteers were compared. Logistic regression analysis was conducted to examine the factors associated with cervical SCC on MRI.

RESULTS

In cases with adult scoliosis, preoperative major scoliosis curve was 56.0° ± 18.8°, and cervical SCC was detected in 25 patients (9.3%). Among the healthy volunteers, 64 cases with cervical SCC were detected. Only in cases with adult scoliosis, logistic regression analysis revealed higher age (OR 1.09, 95% CI 1.04-1.14, P < .001), narrow canal diameter (OR 2.27, 95% CI 1.35-3.85, P = .002), and inferior sagittal balance (OR 2.45, 95% CI 1.02-5.89, P = .04) as significant risk factors. In the logistic regression analysis in all subjects (including adult scoliosis and healthy volunteers), higher age (OR 1.08, 95% CI 1.06-1.10, P < .001) and narrow canal diameter (OR 1.62, 95% CI 1.37-1.92, P < .001) were also found to be significant risk factors, but the presence of scoliosis was not a significant factor.

CONCLUSIONS

Adult scoliosis itself was not significantly associated with cervical SCC. Inferior sagittal balance in addition to scoliosis constituted a significant risk factor for cervical SCC.

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.

Postoperative alterations of sagittal cervical alignment and risk factors for cervical kyphosis in 124 Lenke 1 adolescent idiopathic scoliosis patients

BACKGROUND

This study aims to analyze postoperative changes of cervical sagittal curvature and to identify independent risk factors for cervical kyphosis in Lenke type 1 adolescent idiopathic scoliosis (AIS) patients.

METHODS

A total of 124 AIS patients who received all-pedicle-screw instrumentation were enrolled. All patients were followed up for at least 2 years. The following parameters were measured preoperatively, immediately after the operation, and at the last follow-up: pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracic kyphosis (TK), global thoracic kyphosis (GTK), proximal thoracic kyphosis (PrTK), T1-slope, cervical lordosis (CL), McGregor slope (McGS), sagittal vertical axis (SVA), C2-7 SVA (cSVA), and main thoracic angle (MTA). Statistical analysis was performed to evaluate postoperative alterations of and correlations between the parameters and to identify risk factors for cervical kyphosis. Statistical significance was set at P < 0.05.

RESULTS

After the operation, PrTK and T1-slope significantly increased (3.01 ± 11.46, 3.8 ± 10.76, respectively), cervical lordosis improved with an insignificant increase (- 2.11 ± 13.47, P = 0.154), and MTA, SS, and LL decreased significantly (- 33.68 ± 15.35, - 2.98 ± 8.41, 2.82 ± 9.92, respectively). Intergroup comparison and logistic regression revealed that preoperative CK > 2.35° and immediate postoperative GTK < 27.15° were independent risk factors for final cervical kyphosis, and △T1-slope < 4.8° for a kyphotic trend.

CONCLUSIONS

Postoperative restoration of thoracic kyphosis, especially proximal thoracic kyphosis, and T1-slope play a central role in cervical sagittal compensation. Preoperative CK, postoperative small GTK, and insufficient △T1-slope are all independent risk factors for cervical decompensation.

Sagittal Plane Deformities in Children with SMA2 following Posterior Spinal Instrumentation

This is a retrospective radiographic review to assess post-operative sagittal plane deformities in patients with Spinal Muscular Atrophy type 2 that had been treated with posterior spinal instrumentation. Thirty-two patients with a history of either spinal fusion (N = 20) or growing rods (N = 12) were identified with an average of 7.6 (2.1-16.6) years post-operative follow-up. Forty percent (13/32) of the patients were identified as having obvious "tucked chin" (N = 4), "tipped trunk" (N = 9), or both (N = 3). Sacral incidence was the only parameter that was statistically significant change between pre-operative or immediate post-operative measurements (66.9° vs. 55.2° p = 0.03). However, at final follow-up, the post-operative thoracic kyphosis had decreased over time in those that developed a subsequent sagittal deformity (24.2°) whereas it increased in those that did not (44.7°, p = 0.008). This decrease in thoracic kyphosis throughout the instrumented levels, resulted in a greater lordotic imbalance (30.4° vs. 5.6°, p = 0.001) throughout the instrumented levels in the group that developed the subsequent cervical or pelvic sagittal deformities. In conclusion, sagittal plane deformities commonly develop outside the instrumented levels in children with SMA type 2 following posterior spinal instrumentation and may be the result of lordotic imbalance that occurs through continued anterior growth following posterior instrumentation.

Analysis of reciprocal changes in upper cervical profiles after posterior spinal fusion with the simultaneous double rod rotation technique for adolescent idiopathic scoliosis

BACKGROUND

The relationship between postoperative change of cervical lordotic alignment and restoration of thoracic kyphosis with adolescent idiopathic scoliosis (AIS) is still controversial. We investigated reciprocal changes in the sagittal profiles of the upper and middle-lower cervical spinal segments after posterior spinal fusion with the simultaneous double rod rotation technique (SDRRT) for AIS.

HYPOTHESIS

Occiput-C2 and C2-C7 sagittal profiles of patients with AIS could change significantly after surgical adequate increase of thoracic kyphosis with SDRRT.

PATIENTS AND METHODS

Twenty-seven consecutive patients with AIS treated with the SDRRT were retrospectively reviewed. We investigated the following parameters preoperatively, postoperatively, and at the 2-year follow-up: the Cobb angles of main thoracic curves; C7 sagittal vertical axis; thoracic kyphosis (TK) from T5 to T12; lumbar lordosis from L1 to S1; chin-brow vertical angle; McGregor's slope; occiput to C2 Cobb angle (O-C2angle); C2-C7 Cobb angle (C2-C7angle); T1-slope; and C2-C7 sagittal vertical axis. Additionally, the Scoliosis Research Society questionnaire was completed preoperatively and at the 2-year follow-up. Patients were categorized according to preoperative TK (T5-T12) into hypokyphotic (TK<20°) and normo-hyperkyphotic (TK≧20°) groups. To assess the effect of corrective surgery on sagittal profiles, we investigated correlations among the changes in sagittal parameters.

RESULTS

The mean preoperative TK was 6.1±3.7° in the Hypokyphotic group and 23.5±4.7° in the Normo-hyperkyphotic group (p<0.001), which was significantly improved postoperatively (22.3±4.4° and 26.1±2.6°, respectively; p=0.02) and at the 2-year follow-up (23.0±6.3° and 26.8±5.0°, respectively; p=0.04). The mean preoperative C2-C7angle reflected kyphosis (7.4±9.8°) in the Hypokyphotic group, and, in contrast, lordosis (-8.8±6.8°) in the Normo-hyperkyphotic group (p<0.001), which improved toward greater lordosis postoperatively (-3.7±5.8° and -14.8±5.1°, respectively; p<0.001) and at the 2-year follow-up (-5.1±4.4° and -15.3±6.4°, respectively; p<0.001). On the other hand, the mean preoperative O-C2angle was -20.5±6.5° in the Hypokyphotic group and -13.1±2.8° in the Normo-hyperkyphotic group (p=0.002), which was significantly changed postoperatively (-12.6±6.4° and -7.7±4.3°, respectively; p=0.04) and at the 2-year follow-up (-13.1±6.3° and -7.9±4.3°, respectively; p=0.04). ΔC2-C7 was negatively correlated with ΔT5-T12 (r=-0.298) and ΔO-C2angle (r=-0.332).

DISCUSSION

Lordotic reciprocal alignment changes in the C2-C7angle can occur after adequate restoration of TK. The O-C2angle compensates the C2-C7angle for a maintained horizontal gaze. O-C2 and C2-C7 sagittal profiles of patients with AIS changed significantly after corrective surgery with SDRRT.

LEVEL OF EVIDENCE

IV, Case-series.

Changes in Cervical Spinal Alignment After Thoracolumbar Corrective Surgery in Adult Patients With Adolescent Idiopathic Scoliosis

STUDY DESIGN

Case-control study.

OBJECTIVE

To examine factors influencing cervical alignment after corrective surgery for adult patients with adolescent idiopathic scoliosis (AdIS) SUMMARY OF BACKGROUND DATA.: Corrective surgery for spinal deformity influences postoperative cervical spinal alignment, but changes in the cervical alignment in adults with AdIS are scarcely reported.

METHODS

We retrospectively examined 85 patients with AdIS who underwent posterior corrective surgery for thoracic or lumbar major curve and were followed up for 2 years. Clinical characteristics, radiographic parameters, and health-related quality of life (HRQOL) were evaluated. Cervical deformity (CD) was defined as one of the following cases: (1) T1 tilt minus C2-C7 angle more than 20°, (2) C2-C7 SVA more than 40 mm, (3) and C2-C7 angle less than -10°. Patients were divided into those with and without CD based on the defined criteria; statistically relevant factors were analyzed.

RESULTS

There were 19 patients in the postoperative CD group. The average age at the time of surgery was lower in the CD group (26.5 vs. 31.4). In the CD group, the average preoperative T1 tilt was smaller (1.1° vs. 12.5°), and the C2-C7 angle was kyphotic (-16.1° vs. 3.0°). The average kyphotic angle at thoracic spine (T5-T12) was lower in the CD group preoperatively (12.5° vs. 19.5°) and postoperatively (15.2° vs. 20.8°). HRQOL outcomes were comparable between the groups. Of the patients with preoperative CD, 51.5% (n = 17) maintained their deformity at the final follow-up, and baseline C2-C7 angle was lower than those who converted to non-CD following surgery (n = 16) (-17.0° vs. -10.3°).

CONCLUSION

More than half of the patients with baseline CD maintained their cervical malalignment postoperatively. Patients with postoperative CD presented cervical kyphotic and thoracic hypokyphotic alignments before surgery. Because CD has the potential to lead to cervical degeneration, careful follow-up observation is necessary for these young patients.

LEVEL OF EVIDENCE

3.

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.

Evaluating Cervical Sagittal Alignment in Cervical Myelopathy: Are Sitting Cervical Radiographs and Standing Whole-Spine Radiographs Equally Useful?

STUDY DESIGN

Retrospective review of medical charts and radiographic data.

OBJECTIVES

We aimed to clarify the differences in cervical alignment findings between sitting cervical lateral radiographs and standing whole-spine lateral radiographs with clavicle positioning in cervical spondylotic myelopathy (CSM) patients.

METHODS

We retrospectively evaluated the radiographs of 50 consecutive patients who underwent cervical surgery for CSM in our hospital. Cervical sagittal alignment was evaluated based on the C0-2 angles and C2-7 Gore and Cobb angles. Head position was evaluated in terms of the center of gravity of the head to C7 (CGH-C7) angle and the McGregor angle (ie, the angle between the McGregor line and a horizontal line). The T1-slope was also evaluated.

RESULTS

The mean values of the CGH-C7 angle and T1-slope were significantly lower, while the mean value of the McGregor angle was significantly higher on whole-spine lateral radiographs with clavicle positioning than on sitting cervical lateral radiographs. The mean values of the C0-2 and C2-7 angles did not differ significantly between the 2 radiographic positioning approaches.

CONCLUSIONS

Using whole-spine lateral radiographs with clavicle positioning may result in a significantly lower T1-slope and a posterior tilt of the head. In the absence of a compensatory change in cervical alignment, clavicle positioning may force patients to adopt an upward gazing position of the head. These compensatory mechanisms should be considered while evaluating cervical alignment on whole-spine lateral radiographs with clavicle positioning. Surgical planning should take into account the effect of posture on the radiographic appearance of cervical alignment.

Cervical sagittal alignment and the impact of posterior spinal instrumented fusion in patients with Lenke type 1 adolescent idiopathic scoliosis

Background

Clinical decision making, preoperative planning, and surgical correction for adolescent idiopathic scoliosis (AIS) has traditionally focused on obtaining the maximum coronal plane correction to improve cosmesis and function. More recently, restoring sagittal alignment has also received increasing attention in AIS patients, correlating with positive health-related quality of life (HRQOL) outcomes in multiple studies. In this realm, cervical sagittal alignment (CSA) has also emerged as one of the variables that may correlate with clinical and functional outcomes in AIS patients undergoing surgical correction. Several studies have focused on studying the cervical sagittal plane parameters in patients with spinal deformity, while few have investigated the impact of surgical correction on CSA. In this study, we aimed to capture the baseline cervical sagittal characteristics and evaluate the changes in CSA in a cohort of AIS patients with Lenke type I curves following posterior spinal instrumented fusion (PSIF).

Methods

We evaluated our longitudinal database of patients who had surgical correction for AIS between January 1, 2015 and September 1, 2017. The initial search yielded 270 patients. Next, the following inclusion criteria were applied to identify the study cohort: (I) patients who had Lenke type 1 curves, (II) patients with adequate pre-operative and post-operative radiographs (posterior-anterior and lateral), (III) patients who had a minimum radiographic follow-up of 6 months, and (IV) patients who were treated with the same standard rod instrumentation system. In addition, the following exclusion criteria were applied: (I) patients with neuromuscular disorders, (II) patients with prior spine surgery, and (III) those who received greater than Schwab-2 osteotomies. A total of 30 patients were included in our final analysis. The C2-C7 angle, C0-C2 angle, C2-C7 sagittal vertical axis (SVA), McGregor slope (McGS), and the T1 slope angle were measured preoperatively and at 6 months. A kyphotic measurement was assigned a negative value while positive values were used to describe lordotic measurements. Descriptive statistics and paired sample t-test were used to compare pre-and post-operative data with a cutoff P value of 0.05 to determine statistical significance.

Results

Overall, CSA improved in most patients post-operatively, with 19/30 (63%) resulting in improved lordosis. Pre-operatively, mean C2-C7 cervical lordosis was -4.3°, which improved to -0.5° postoperatively (P=0.075), with a mean difference of 3.7°. Simultaneously, mean C0-C2, C2-C7 SVA, McGS, and T1 slope changed from 17° (range, -18° to 41°), 26.5 mm (range, 10 to 45 mm), 4° (range, -7.5° to 25°), and 17.4° (range, 1° to 42°) to 16° (range, 0° to 34.4°, mean difference =1.01°, and P=0.548), 28.2 mm (range, 9 to 57 mm, mean difference =2 mm, and P=0.244), 4.03°, (range, -7.8° to 25°, mean difference =0.16, and P=0.916), and 18° (range, 5.4° to 42°, mean difference =0.37, and P=0.761) (mean change of C2-C7 angle of 3.76°).

Conclusions

This study demonstrated baseline cervical kyphosis and a trend towards cervical lordosis restoration in patients with AIS and a Lenke type 1 curve who underwent PSIF. This study adds to emerging evidence and, together with further studies, will help estimate the impact of PSIF on the cervical sagittal profile, the effect of CSA on patient reported outcomes, and ways to address cervical sagittal malalignment when undertaking the surgical correction for specific curve types in AIS.