Sagittal Profile Response of Cervical Spine After Posterior Correction in Thoracic and Lumbar Adolescent Idiopathic Scoliosis: Correlation with Thoracic Kyphosis?

Neck and shoulder pain in thoracic adolescent idiopathic scoliosis 10 years after posterior spinal fusion

PURPOSE

We aimed to determine the clinical significance of neck and shoulder pain (NSP) 10 years after posterior spinal fusion (PSF) for thoracic adolescent idiopathic scoliosis (AIS) and the relationship between radiographic parameters and NSP.

METHODS

Of 72 patients who underwent PSF for thoracic AIS (Lenke 1 or 2) between 2000 and 2013, we included 52 (46 females; Lenke type 1 in 34 patients and type 2 in 18; mean age, 25.6 years) who underwent NSP evaluation using visual analog scale (VAS, 10 cm) 10 years postoperatively (follow-up rate, 72.2%). Correlation analyses were performed using Spearman's rank correlation coefficient (r).

RESULTS

The VAS for NSP was 2.6 cm in median and 3.4 cm in mean at 10 years. The VAS had significant negative correlations with several SRS-22 domain scores (rs = - 0.348 for pain, - 0.347 for function,  -  0.308 for mental health, and - 0.372 for total) (p < 0.05). In addition, the VAS score was significantly correlated with cervical lordosis (CL) (rs = 0.296), lumbar lordosis (rs = - 0.299), and sacral slope (rs = 0.362) (p < 0.05). Furthermore, at the 10-year follow-up, CL was significantly negatively correlated with T1 slope (rs = - 0.763) and thoracic kyphosis (TK) (- 0.554 for T1-12 and - 0.344 for T5-12) (p < 0.02).

CONCLUSION

NSP was associated with deterioration in SRS-22 scores, indicating that NSP is a clinically significant long-term issue in PSF for thoracic AIS. Restoring or maintaining the TK and T1 slopes, which are controllable factors during PSF, may improve cervical lordosis and alleviate NSP at 10-year follow-up.

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.

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.

Can C7 Slope Substitute the T1 Slope in Idiopathic Scoliosis Patients? A Radiographic Study

BACKGROUND

The aim of this study was to investigate whether C7 slope can be used as a substitute for T1 slope in idiopathic scoliosis.

METHODS

From January 2014 to October 2019, 101 patients who received posterior spinal internal fixation and fusion in our hospital were retrospectively analyzed. After analyzing the visibility of vertebral endplates, 46 cases of C7/T1 vertebral endplates were visible, including 14 males and 32 females, aged 9 to 18 years (mean 14.6±2.0 y). The upper C7 slope, lower C7 slope, T1 slope, cervical lordosis and C2 to 7 sagittal vertebral axis were measured before and after operation and at the last follow-up. Pearson correlation coefficient was used to evaluate the correlation strength between upper C7 slope and T1 slope, and lower C7 slope and T1 slope. Through simple linear regression analysis, linear regression equations were generated from the upper and lower C7 slopes to predict T1 slope.

RESULTS

According to the 2 researchers' judgment, the visibility rate of the upper C7 endplate was 93.1% before operation, 93.1% after operation, and 91.1% at the last follow-up. The lower C7 endplate's visible rate was 72.3% before operation, 70.3% after operation and 68.3% at the last follow-up. The visible rate of T1 upper endplate was 52.5% before operation, 48.5% after operation and 50.5% at last follow-up. Linear regression analysis showed that the upper C7 slope and T1 slope in idiopathic scoliosis patients, regardless of preoperative (r=0.908, P<0.01), postoperative (r=0.0.886, P<0.01), follow-up (r=0.899, P<0.01), or overall (r=0.895, P<0.01), both have a close correlation; the lower C7 slope and the T1 slope are the same before surgery (r=0.882, P<0.01), after surgery (r=0.940, P<0.01), follow-up (r=0.952, P<0.01), or overall (r=0.929, P<0.01) all have statistical significance.

CONCLUSION

When the upper endplate of T1 is not visible on standard radiographs, the upper or lower C7 slope can be used as a reliable alternative measurement parameter for sagittal balance assessment.

Surgical increase in thoracic kyphosis predicts increase of cervical lordosis after thoracic fusion for adolescent idiopathic scoliosis

PURPOSE

The modification of cervical lordosis (CL) after adolescent idiopathic scoliosis (AIS) surgery is influenced by the correction of thoracic hypokyphosis. The quantification of the increase of CL as a function of the increase of thoracic kyphosis (TK) has never been calculated.

METHODS

A total of 92 consecutive AIS patients who underwent a posterior thoracic selective fusion, corrected by simultaneous translation on 2 rods technique, with minimum 24-month follow-up, were analyzed from a prospective database. We evaluated global sagittal kyphosis and lordosis. CL was divided by the horizontal line in proximal (PCL) and distal cervical lordosis (DCL), likewise TK in proximal (PTK) and distal TK (DTK), and lumbar lordosis (LL) in proximal (PLL) and distal LL (DLL).

RESULTS

The mean TK gain was 16°, 14° and 28° in the whole cohort, normokyphosis group and hypokyphosis group, respectively. The mean DCL gain was, respectively, 9°, 7° and 20° and the mean CL gain 8°, 5° and 21°. There was a strong correlation between TK gain and CL gain (coefficient = 0.86) and between TK gain and DCL gain (coefficient = 0.74). The regression equation was defined as DCLgain = - 3 + 0.75 × TKgain (p < 0.0001) corresponding on average to 60% of the TK gain.

CONCLUSION

60% of the TK gain was transferred to DCL gain. Correlations reflect the geometrical equivalence between PTK and DCL. The use of sagittal global measurements shows that DCL is equivalent to PTK and can be expressed as a function of pelvic parameters (DCL = PT + LL-PI). DCL must be considered to optimize the postoperative sagittal alignment of the spine.

The Correlation Between Postoperative Cervical Sagittal Alignment and Spine Sagittal Alignment in Adolescent Idiopathic Scoliosis: A Meta-Analysis

OBJECTIVE

To perform a meta-analysis exploring the correlation between cervical lordosis (CL) and sagittal spine alignment in patients with adolescent idiopathic scoliosis (AIS) after surgery for determining a surgical strategy.

METHODS

We searched 3 electronic databases for studies discussing the correlation between CL and spine sagittal alignment in patients with AIS. Studies reported from the inception of the database to June 2019 were retrieved without any language restrictions. Summary correlation coefficient (r) values were extracted from each study, and 95% confidence intervals (CIs) were calculated. In addition, we conducted subgroup analyses in different curve type subgroups with at least 2 studies.

RESULTS

Ten relevant studies involving 539 patients were evaluated in this meta-analysis. The Pearson correlation (r) for CL and the T1 slope was -0.69; (95% CI, -0.79 to -0.54). The fixed-effects summary correlation between CL and thoracic kyphosis in patients was moderate (r = -0.40; 95% CI, -0.48 to -0.31). In addition, the fixed-effects summary correlations between CL and lumbar lordosis (r = 0.19; 95% CI, 0.07-0.30), pelvic incidence (r = -0.08; 95% CI, -0.20 to 0.04), pelvic tilt (r = -0.06; 95% CI, -0.18 to 0.06), and sacral slope (r = -0.06; 95% CI, -0.18 to 0.06) in patients were weak.

CONCLUSIONS

There is a strong negative correlation between CL and the T1 slope in patients with AIS. Given the lack of robust clinical evidence, these findings warrant verification by large prospective registries and randomized trials with long follow-up periods.