A Positive (+ve) Postoperative Upper Instrumented Vertebra Tilt Angle (≥0°) Significantly Increases the Risk of Medial Shoulder and Neck Imbalance in Lenke 1 and 2 Adolescent Idiopathic Scoliosis Patients

Flexibility-tilt agreement best predicts shoulder balance following posterior spine fusion for adolescent idiopathic scoliosis

PURPOSE

We propose a novel concept, called flexibility-tilt agreement (FTA), which could be applied intra-operatively to improve shoulder balance following posterior spine fusion for Adolescent Idiopathic Scoliosis (AIS). We retrospectively applied this concept to a cohort with thoracic-only curves, seeking to: (1) evaluate the impact of FTA and other peri-operative variables on post-operative shoulder balance, and (2) evaluate deformity characteristics associated with achieving FTA.

METHODS

A single-institution registry was queried for patients undergoing PSF from 2000 to 2017 with main thoracic and double thoracic curves with at least 2-year follow-up. Flexibility was defined as the Cobb angle of the unfused proximal thoracic curve (cephalad to chosen UIV) on pre-operative bender. Tilt refers to post-operative UIV tilt angle. FTA means these values cancel (Flexibility + Tilt = 0 ± 5°). Logistic regression was performed to determine the association between peri-operative variables and shoulder balance.

RESULTS

One hundred and sixty-one patients were included, mean age 13.6 years old, and 47-month mean follow-up. FTA was achieved in 74 (46%) patients and was associated with post-operative (OR = 4.59) and final (OR = 6.98) medial shoulder balance with a threshold of 6° (AUC = 0.77, p = 0.038). FTA was the best predictor of shoulder balance of all tested variables.

CONCLUSION

Patients that showed flexibility-tilt agreement, or FTA, had vastly increased odds of medial and lateral shoulder balance at a minimum of 2-year follow-up for all thoracic curves. Future studies can evaluate whether applying FTA to determine intra-operative corrective maneuvers prospectively leads to improvements in shoulder balance.

LEVEL OF EVIDENCE

Level III-retrospective comparative study.

Assessment of Neck Imbalance in Adolescent Idiopathic Scoliosis Patients: A Cross-Section Study Based on Body Image of 115 Patients with Main or Double Thoracic Curve

OBJECTIVE

Neck imbalance negatively affects body aesthetics of adolescent idiopathic scoliosis (AIS) patients. The evaluation of neck imbalance is currently limited to radiographic parameters, but lacks visual indicators. Therefore, the purpose of this study was to establish indexes of neck imbalance based on body image and to investigate whether these indexes can truly reflect neck imbalance in AIS patients.

METHODS

We performed a cross-sectional study at a single institution between June 2017 and September 2020 and there were 115 subjects involved in this research. All patients were diagnosed with adolescent idiopathic scoliosis, Lenke type I/II. Radiographic parameters measured included cervical axis tilt (CAT), T1 tilt, first rib angle (FRA), clavicle angle (CA), radiographic shoulder height (RSH), proximal thoracic curve (PTC), apical vertebra translation of proximal thoracic (AVT of PT), main thoracic curve (MTC), apical vertebra translation of main thoracic (AVT of MT) and coronal balance (CB/C7PL-CSVL). Neck imbalance indexes were obtained and measured following a standardized manner. Intra-class correlation coefficient (ICC) analysis was performed for neck imbalance indexes to determine their intra-observer and inter-observer reliability, and correlation tests were performed for neck imbalance indexes with the radiographic parameters mentioned above.

RESULTS

Strong intraobserver and interobserver reliability were observed in neck imbalance index (NII) 1 (0.91 and 0.88), neck imbalance index 2 (0.85 and 0.81) and NII 3 (0.82 and 0.80), P < 0.05. Significant correlation was found in cervical axis tilt (R = 0.81 for NII 1, R = 0.77 for NII 2 and R = 0.78 for NII 3), T1 tilt (R = 0.43 for NII 1, R = 0.52 for NII 2 and R = 0.48 for NII 3), first rib angle (R = 0.41 for NII 1, R = 0.48 for NII 2 and R = 0.43 for NII 3), proximal thoracic curve (R = 0.36 for NII 2) and apical vertebra translation of proximal thoracic (R = -0.37 for NII 2 and R = -0.35 for NII 3) with neck imbalance indexes. Neck imbalance index 1 showed the highest correlation with cervical axis tilt (R = 0.81, P < 0.01).

CONCLUSIONS

Neck imbalance indexes established in our study were in good correlation with cervical axis tilt (CAT), At the meantime, they showed significant correlations with T1 tilt and first rib angle (FRA). Our study provides a practical method for measurement of neck imbalance regarding realistic perspective and makes up for the lack of photographic indexes about neck imbalance.

Incidence and risk factors of postoperative medial shoulder imbalance in Lenke Type 2 adolescent idiopathic scoliosis with lateral shoulder balance

BACKGROUND

In clinical practice, there are a significant percentage of Lenke 2 AIS patients suffered from medial shoulder imbalance (MSI) despite achieving good lateral shoulder balance (LSB) following surgery. However, there are few studies evaluating the features of the medial shoulder. The objective of this study was to determine the incidence and independent risk factors of MSI with LSB after Lenke 2 AIS corrective surgery.

METHODS

One hundred and twenty Lenke 2 AIS patients with LSB at the last follow-up were reviewed from 2009 to 2018. Preoperative, and 3-month and the last postoperative follow-up radiographs were measured using a number of specific measurements. At the last follow-up, patients were divided into medial shoulder balance (MSB) group and the MSI group according to whether the T1 tilt was greater than 3°. A stepwise multiple linear regression analysis was used to examine the independent risk factors for MSI. Scoliosis Research Society (SRS)-30 questionnaire was used to assess clinical outcomes.

RESULTS

Up to 69.2% of patients suffered from MSI with LSB after Lenke Type 2 AIS corrective surgery. Multiple regression showed that postoperative upper instrumented vertebra tilt (UIVt), proximal thoracic curve (PTC), the ratio of PTC and main thoracic curves (PTC/MTC) and T2 vertebra rotation ratio (T2-VR) were significant predictors for MSI (UIVt: b = 0.398, p < 0.001; PTC/MTC: b = 2.085, p < 0.001; PTC: b = 0.155, p < 0.001; T2-VR: b = 3.536, p = 0.008; adjusted R² = 0.711). 72 patients completed the SRS-30 questionnaire survey, and the MSB group were scored the higher (p ≤ 0.001) in self-image domain (4.18 ± 0.43 vs. 3.70 ± 0.35), satisfaction domain (4.39 ± 0.54 vs. 3.95 ± 0.46) and total average (4.31 ± 0.23 vs. 4.11 ± 0.19).

CONCLUSION

Although the patients with Lenke 2 AIS achieve LSB after corrective surgery, up to 69.2% of them suffered from MSI. Postoperative UIVt, PTC, PTC/MTC and T2-VR were significant predictors for MSI. Sufficient correction of these variables may facilitate the achievement of MSB.

Does the Distal Level Really Matter in the Setting of Health-Related Quality of Life? Assessment of a Series of Adolescent Idiopathic Scoliosis Patients at More Than 7 Years Following Surgery

STUDY DESIGN

Retrospective longitudinal study.

OBJECTIVE

The main goal of this study was to measure the disability after AIS correction, according to the LIV.

SUMMARY OF BACKGROUND DATA

Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine that may require surgical correction. If the upper and lower instrumented levels (UIV and LIV) of these fusions are defined by the characteristics of the curve, the long-term consequences of the LIV choices are still partially unknown.

METHODS

This retrospective longitudinal study collected demographic, radiologic (Lenke classification, Cobb angle), and surgical data (approach, LIV, UIV) on 116 patients operated for AIS fusion on a specialized pediatric spine center were collected. All participants answered SRS30, SF12, lumbar and leg pain Visual Analogue Scales (VAS) at last follow-up. Statistical analysis between LIV (T12L1, L2, L3 or L4L5) and clinical data at last follow-up was realized.

RESULTS

The mean follow-up was 87months. The mean increase of back pain VAS per UIV level was 9 mm. No statistically significant difference between the different LIV was found, for SRS30 or SF12 MCS (mental component scale). There was a statistically significant difference between L3 UIV and L4L5 UIV for SF-12 PCS (physical component scale); ( P = 0.03).

CONCLUSION

The long-term consequences of LIV choice mostly affect levels distal to L3. If the LIV is mostly defined by the characteristics of the curve, one level caudally corresponds to +9 mm of back pain VAS at 7 years of follow-up. Surgeons may be aware of the long-term consequence of LIV choice and patients be informed.

What is the impact of scoliotic correction on postoperative shoulder imbalance in severe and rigid scoliosis

Background

Although recent studies have investigated the risk factors for PSI, few studies have focused on the impact of scoliotic correction on postoperative shoulder imbalance (PSI), especially in severe and rigid scoliosis (SRS). The purpose of the study was to study the effect of scoliotic correction on PSI in SRS.

Methods

The preoperative, postoperative, and minimum 2-year follow-up radiographs of 48 consecutive patients with SRS who underwent posterior spinal fusion surgery were evaluated. We regarded radiographic shoulder height (RSH) as a shoulder balance parameter and divided the patients into improved and aggravated groups of PSI from pre- to post-operation and from post-operation to last follow-up, respectively. In addition, patients were divided into nine groups based on the observed changes in PSI after surgery and at follow-up, and the correction rate ratios were calculated among the groups. Independent samples T test and Chi-squared test were performed between the improved and aggravated groups of PSI.

Results

After surgery, the proximal thoracic curve (PTC) flexibility (P = 0.040), correction rate of the main thoracic curve (MTC) (P = 0.010), and Cobb angle of the lumbar curve (LC) (P = 0.037) were significantly higher, while the ratio of the correction rate of the PTC to the MTC (P = 0.042) was smaller in the aggravated group. At follow-up, the improved group had significantly larger PTC flexibility (P = 0.006), larger ratio of the correction rate of PTC to MTC (P = 0.046), a larger ratio correction rate of PTC to LC (P = 0.027), and a smaller correction rate of LC (P = 0.030). The correction rate ratios of the groups after surgery were as follows: negative to negative (N-N) (1.08) > negative to balance (N-B) (0.96) > negative to positive (N-P) (0.67), B-N (1.26) > B-B (0.94) > B-P (0.89), and P-N (0.34) > P-P (0.83). The order of the correction rate ratio at follow-up was as follows: N-N (0.96) > N-B (0.51), B-B (0.97) > B-P (0.90), and P-B (0.87) > P-P (0.84).

Conclusion

Harmonizing the correction rate ratio of the PTC, MTC, and LC should be recommended for intraoperative correction and postoperative compensation of PSI. In addition, greater PTC flexibility plays an important role in the spontaneous correction and compensation of PSI in SRS.

A Nomogram to Predict the Occurrence and Development of Postoperative Neck Tilt in Lenke I and II AIS Patients

OBJECTIVE

To investigate the risk factors and to construct a nomogram for the prediction of postoperative neck tilt (PNT) in patients with Lenke I and II adolescent idiopathic scoliosis (AIS).

METHODS

A total of 95 patients with Lenke I and II AIS who underwent posterior segmental spinal instrumentation and fusion between the years 2010 and 2018 (with an average 2-year follow-up) at a single institution were retrospectively investigated. The full spine X-rays of patients were measured preoperatively, postoperatively, and at the final follow-up. Variables were compared between the PNT group (n = 33) and the non-PNT group (n = 62), and univariate and multivariate logistic regressions were performed to identify the independent predictors for the occurrence of PNT. The discrimination and calibration of the nomogram were validated by the receiver operating characteristic curve and calibration curve.

RESULTS

Variables including the preoperative neck tilt, postoperative upper instrumented vertebrae imbalance, postoperative T1 tilt, and decreasing values in the main thoracic curve (ΔMTC) minus decreasing values in the proximal thoracic curve (ΔPTC) (ΔMTC - ΔPTC) were identified as the predictors for the nomogram. The area under the receiver operating characteristic curve was 0.900 (95% confidence interval, 0.857-0.932). Meanwhile, the calibration curve revealed good agreement, and the Hosmer and Lemeshow test determined that the model was well fitted.

CONCLUSIONS

Preoperative neck tilt, postoperative upper instrumented vertebrae imbalance, postoperative T1 tilt, and ΔMTC-ΔPTC are predictors for the nomogram. The nomogram can provide surgeons with a simple and effective tool to predict the occurrence and development of patients with PNT in Lenke I and II AIS.