Postoperative shoulder imbalance in Lenke Type 1A adolescent idiopathic scoliosis and related factors

Does Sacral Slanting Affect Postoperative Shoulder Balance in Patients With Lenke Type 2A Adolescent Idiopathic Scoliosis?

OBJECTIVE

Even minor sacral slanting can influence T1 tilt and shoulder balance. Yet, the relationship between sacral slanting and postoperative shoulder imbalance (PSI) has not been previously explored. To determine risk factors for PSI in Lenke 2A adolescent idiopathic scoliosis (AIS) patients, with an emphasis on sacral slanting.

METHODS

The study encompassed 96 consecutive patients who had undergone posterior correction and fusion surgery for Lenke type 2A AIS. Patients were grouped into PSI(+) and PSI(-) based on postoperative outcomes. Additionally, they were classified into left-sided slanting, no slanting, and right-sided slanting groups according to the degree of sacral slanting. Various radiological measures were compared.

RESULTS

Patients in the PSI(+) group exhibited a smaller preoperative proximal thoracic curve and a higher main thoracic curve correction rate than those in the PSI(-) group. The presence or absence of sacral slanting did not exhibit a significant variation in PSI occurrence. However, the right-sided sacral slanting group showed a larger delta radiologic shoulder height compared to the other 2 groups (7.1 mm vs. 1.5 & 3.3 mm).

CONCLUSION

Sacral slanting was not directly linked to the development of PSI. Despite the common postoperative elevation of the left shoulder, the shoulder height differences decreased over the follow-up period. Especially in cases with a right-sided tilted sacrum, the PSI demonstrated progressive improvement, with an associated increase in the rightward distal wedging angle, leading to distal adding-on.

Relationship between Fusion Mass Shift and Postoperative Distal Adding-on in Lenke 1 Adolescent Idiopathic Scoliosis after Selective Thoracic Fusion

STUDY DESIGN

This is a retrospective cohort study.

PURPOSE

This study aims to investigate the risk factors for postoperative distal adding-on in Lenke 1 adolescent idiopathic scoliosis (AIS) and validate the relationship between fusion mass shift (FMS) and postoperative distal adding-on.

OVERVIEW OF LITERATURE

Postoperative distal curve adding-on is one of the complications in AIS. FMS has been proposed to prevent postoperative distal adding-on, which requires further validation from different institutions.

METHODS

This study included 60 patients with Lenke 1 AIS who underwent selective thoracic fusion surgery. Coronal spinal alignment parameters were analyzed preoperatively, postoperatively, and at the final follow-up. The postoperative FMS was divided into two groups: the balanced group (FMS ≤20 mm) and the unbalanced group (FMS >20 mm). An independent t-test was used to compare quantitative data between groups, and a chi-square test was used for qualitative data. Furthermore, binary logistic regression and receiver operating characteristics curve analyses were used to identify the risk factors for postoperative distal adding-on in AIS.

RESULTS

At 2-year follow-up, the unbalanced group was more likely to have adding-on (17 of 24 patients) than the balanced group (six of 36 patients; p<0.001). Twenty-three patients with distal adding-on had significantly greater preoperative and postoperative lower instrumented vertebrae (LIV) rotation, FMS, and FMS angle (FMSA) than those without postoperative distal adding-on. Binary logistic regression analysis selected three independent risk factors for adding-on incidence after surgery: FMS (odds ratio [OR], 1.115; 95% confidence interval [CI], 1.049-1.185; p<0.001), FMSA (OR, 1.590; 95% CI, 1.225-2.064; p<0.001), and postoperative LIV rotation (OR, 6.581; 95% CI, 2.280-19.000; p<0.001).

CONCLUSIONS

Achieving a balanced fusion mass intraoperatively is important to avoid postoperative distal adding-on, with FMS of <20 mm and FMS angle of <4.5°. Furthermore, correcting LIV rotation helps to decrease the incidence of postoperative distal addingon.

Preoperative "Cervical Axis" Deviation Increases the Risk of Distal Adding-On Following Surgery in Lenke 1 and 2 Adolescent Idiopathic Scoliosis Patients

STUDY DESIGN

Retrospective.

PURPOSE

To evaluate the relationship between shoulder/ neck imbalance with distal adding-on phenomenon and to identify other risk factors in Lenke 1 and 2 (non-AR curves) adolescent idiopathic scoliosis (AIS) patients.

METHODS

100 Lenke 1 and 2 AIS patients with lowest instrumented vertebra (LIV) cephalad to or at L1 were recruited. Medial shoulder/ neck balance was represented by T1-tilt and cervical axis (CA). Lateral shoulder balance was represented by clavicle angle (Cla-A) and radiographic shoulder height (RSH). Distal adding-on phenomenon was diagnosed when there was disc wedging below LIV of >5^o at final follow-up. Predictive factors and odds ratio were derived using univariate and multivariate logistic regression analysis.

RESULTS

Mean age of this cohort was 15.9 ± 4.4 years. Mean follow-up duration was 30.9 ± 9.6 months. Distal adding-on phenomenon occurred in 19 patients (19.0%). Only Risser grade, preoperative CA and final follow-up lumbar Cobb angle were the independent factors. A positive preoperative CA deviation increased the odds of distal adding-on by 5.4 times (95% CI 1.34-21.51, P = 0.018). The mean immediate postoperative T1-tilt, CA, RSH and Cla-A were comparable between the group with distal adding-on and the group without.

CONCLUSION

Distal adding-on phenomenon occurred in 19.0% of patients. Preoperative "Cervical Axis" was an important factor and it increased the risk of distal adding-on by 5.4 times. Other significant predictive factors were Risser grade and lumbar Cobb angle at final follow-up. Immediate postoperative shoulder or neck imbalance was not a significant factor for postoperative distal adding-on phenomenon.

Preoperative Less Right Shoulder Elevation Had a Higher Risk of Postoperative Shoulder Imbalance When Main Thoracic Curve Shows Higher Correction Regardless of the Upper Instrumented Vertebra Level for Patients with Adolescent Idiopathic Scoliosis Lenke Type 1

STUDY DESIGN

This is a retrospective study.

PURPOSE

This study aimed to investigate the incidence of and risk factors for postoperative shoulder imbalance (PSI) in patients with Lenke type 1.

OVERVIEW OF LITERATURE

PSI is a complication resulting in poor self-image and satisfaction in adolescent idiopathic scoliosis (AIS) patients.

METHODS

We examined the data of AIS patients with Lenke type 1 curves who underwent posterior fusion surgery in a retrospective manner. PSI was defined as a 2-year postoperative absolute radiographic shoulder height (RSH) of ≥2 cm. Patients were divided into two groups based on the presence of PSI and the level of their upper instrumented vertebra (UIV) (UIV at T2 or T3 [U-UIV] or UIV below T3 [L-UIV]). The radiographic parameters and clinical outcomes were compared, and the cutoff values of risk factors were identified by multivariate analysis.

RESULTS

Of 104 patients, 21 (20.2%) had left shoulder elevation PSI. The PSI group had a significantly greater preoperative RSH (-5.1 mm vs. -14.3 mm) and main thoracic (MT) curve correction rate (77.3% vs. 69.1%) than the non-PSI group. The PSI incidence did not differ between the U-UIV and L-UIV groups. Multivariate analysis identified preoperative RSH and the MT curve correction rate as independent risk factors for PSI. The receiver operating characteristic curve analysis identified the preoperative RSH cutoff value as -6.5 mm and MT curve correction rate cutoff value as 76.9%.

CONCLUSIONS

Even in AIS patients with Lenke type 1 curves, the incidence of PSI was relatively high (20.2%). Patients with preoperative lower right shoulder elevation (i.e., RSH >-6.5 mm) had a higher risk of PSI regardless of UIV level when the MT curve showed a higher correction rate (i.e., correction rate >76.9%).

Incidence and Predictive Factors of Shoulder Imbalance After Selective Anterior Spinal Fusion Surgery in Lenke Type 5C Adolescent Idiopathic Scoliosis

Background

No study has assessed the incidence or predictors of postoperative shoulder imbalance (PSI) in patients with Lenke type 5C adolescent idiopathic scoliosis (AIS) who underwent selective anterior spinal fusion (ASF). This study evaluated the incidence and predictors of shoulder imbalance after selective ASF for Lenke type 5C AIS.

Methods

In total, 62 patients with Lenke type 5C AIS (4 men and 58 women, mean age at surgery of 15.5 ± 1.5 years) were included and divided into the following two groups according to the radiographic shoulder height (RSH) at the final follow-up: PSI and non-PSI groups. All patients in this study underwent a whole-spine radiological evaluation. Various spinal coronal and sagittal profiles on radiographs were compared between the 2 groups. The clinical outcomes were assessed using the Scoliosis Research Society (SRS)-22 questionnaires.

Results

The mean final follow-up duration was 8.6 ± 2.7 years. PSI was observed in 10 patients (16.1%) immediately after surgery; however, in the long-term follow-up period, PSI improved in 3 patients spontaneously, whereas the remaining 7 patients had residual PSI. The preoperative RSH and correction rates of the major curve immediately after surgery or at the final follow-up were significantly larger in the PSI group than in the non-PSI group (p=.001, p=.023, and p=.019, respectively). Receiver operating characteristic curve analysis indicated that the cutoff values for preoperative RSH and the correction rates immediately after surgery and at the final follow-up were 11.79 mm (p=.002; area under the curve [AUC], 0.948), 71.0% (p=.026; AUC, 0.822), and 65.4% (p=.021; AUC, 0.835), respectively. No statistically significant difference was observed in the preoperative and final follow-up SRS-22 scores in any domain between the PSI and non-PSI groups.

Conclusions

Paying attention to the preoperative RSH and avoiding excessive correction of the major curve can prevent the occurrence of shoulder imbalance after selective ASF for Lenke type 5C AIS.

Is it Safe to Save Levels and Choose the Lowest Instrumented Vertebra as Touched Vertebra While Selectively Fusing Lenke 1/2 Curves? A Proportional Meta-Analysis of Existing Evidence

STUDY DESIGN

Meta-analysis.

OBJECTIVE

To compare the clinical and radiological outcomes in patients with Adolescent Idiopathic scoliosis (AIS) treated by selective thoracic fusion (STF) with lowest instrumented vertebra (LIV) at touched vertebra (TV) vs stable vertebra (SV).

METHODS

The databases PubMed, Embase and Google Scholar were searched until November 2020.Studies which had Lenke type 1 curves and Lenke type 2 curves in adolescent population treated by STF and which reported pre- and post-operative curve characteristics including correction percentage and complications were included. Studies which did not report the LIV selection, curve correction percentages and whose full text could not be acquired were excluded.

RESULTS

Eight studies were included for analysis of which seven were found to be retrospective studies (level III evidence) and one was prospective study (level II evidence) each. Overall proportional meta-analysis found no significant difference in correction rate, total srs-22 scores, and complication rates.

CONCLUSION

The evaluation of SV group and TV group as LIV for selective thoracic fusions in AIS reveals a comparable outcome in terms of curve correction, patient satisfaction scores and complication rates. The TV can be chosen safely as the LIV especially in type A and B Lenke 1&2 curves, as it saves more motion segments when compared to SV.

Shoulder Imbalance in Adolescent Idiopathic Scoliosis: A Systematic Review of the Current State of the Art

Background

Shoulder imbalance (SI) is among the most rated manifestations of adolescent idiopathic scoliosis (AIS) pointed to by patients and spine surgeons. It serves as a criterion to assess the outcome of scoliosis surgery and is also a cause of dissatisfaction for the patients postoperatively. Despite the availability of multiple studies on this issue, a comprehensive survey of the risk factors and preventive measures has yet to be elucidated. The present study aimed to highlight the most recent approach to the evaluation and management of SI, as well as medical counseling about the expectations and limitations of the surgery.

Methods

A systematic literature review using electric databases was conducted, including PubMed, Embase, the Cochrane Library, and Google Scholar, with a well-defined search strategy on SI definition, risk factors, and preventive and surgical recommendations.

Results

A total of 69 articles were identified; SI > 2 cm was the most used cut-off, and its risk factors included the main thoracic Cobb angle > 80˚, preoperative level shoulder, high left shoulder, and higher Risser grade. The most stated strategies to preclude SI were the sufficient correction of the proximal thoracic curve, and moderate correction of the main thoracic and lumbar curve (LC).

Conclusion

Shoulder imbalance should be prevented not only for appearance or satisfaction but also for possible complications such as distal adding-on, new LC progression, or trunk shift postoperatively in AIS patients.

Shoulder Balance Following Correction Surgery for Adolescent Idiopathic Scoliosis: When Is It Achieved and Does the Type of Construct Matter?

STUDY DESIGN

This is a retrospective study.

OBJECTIVE

This study aims to determine (1) when shoulder rebalancing occurs after adolescent idiopathic scoliosis (AIS) correction surgery and (2) whether shoulder asymmetry was influenced by the use of pedicle screws or hooks.

SUMMARY OF BACKGROUND DATA

Postoperative shoulder imbalance is an important outcome of AIS correction surgery as it may influence a patient's appearance and satisfaction.

MATERIALS AND METHODS

Seventy AIS patients undergoing AIS correction surgery at a single institution were retrospectively reviewed. Radiographic parameters were measured from anteroposterior x-rays at preoperative, immediate postoperative, 6 months postsurgery, and 12 months postsurgery. Shoulder parameters measured were: radiographic shoulder height (RSH), clavicle angle, coracoid height difference (CHD), and T1 tilt. The Cobb angle of the proximal thoracic curve, major thoracic curve, and thoracolumbar/lumbar curve. The percentage of correction was also calculated.

RESULTS

Lateral shoulder asymmetry (RSH and CHD) changed significantly from preoperative to up to 6 months postsurgery. T1 tilt, a measure of medial shoulder asymmetry, did not change significantly. Postoperatively, the hook group attained significantly better shoulder balance than the screw group in terms of RSH and CHD up to 12 months postsurgery. However, the percentage correction of the major thoracic curve was significantly greater in the screw group than the hook group (hook: 62.2±18.4% vs. screw: 76.0±16.0%, P=0.007).

CONCLUSIONS

Lateral shoulder rebalancing occurs up to 6 months after surgery. While thoracic pedicle screws offer greater correction of major AIS curves, hook constructs offer better postoperative shoulder symmetry.

LEVEL OF EVIDENCE

III.

Shoulder balance in patients with Lenke type 1 and 2 idiopathic scoliosis appears satisfactory at 2 years following anterior vertebral body tethering of the spine

BACKGROUND

Shoulder balance is an important factor for patient satisfaction following surgery for idiopathic scoliosis (IS). There is no literature reporting the effect of anterior vertebral body tethering (AVBT) on shoulder balance. The purpose of this study was to report the prevalence of postoperative shoulder imbalance in patients undergoing AVBT for IS.

METHODS

In this retrospective case series, patients enrolled in a multicenter scoliosis registry who underwent AVBT from 2013 to 2017 in two Canadian centers were identified. The primary outcome was shoulder imbalance, defined as an absolute radiographic shoulder height of > 2 cm, at 2 years postoperatively (follow-up range: 22-30 months). Clavicular angle and T1 tilt angle were also investigated.

RESULTS

Of the 50 patients identified (92% female; preoperative age: 11.9 ± 1.4 years), there were 43 (86%) patients with Lenke 1 and 7 (14%) patients with Lenke 2 curves. The mean Cobb angles of the proximal thoracic and main thoracic curves were 22.8° ± 8.8° and 49.4° ± 8.5° preoperatively and 13.1° ± 7.5° and 24.9° ± 9.5° at a mean follow-up time of 2.1 years. Absolute clavicular angle and T1 tilt angle were 2.8° ± 2.2° and 4.8° ± 3.5° preoperatively and 2.2° ± 1.7° and 4.7° ± 4.2° at 2-year follow-up. Preoperatively, absolute shoulder height averaged 15.6 ± 10.4 mm, and 15 (30%) patients had shoulder imbalance. At 2-year follow-up, absolute shoulder height averaged 11.2 ± 8.3 mm, and 8 (16%) patients had shoulder imbalance. Of the patients who had acceptable shoulder balance preoperatively, 4 (11.4%) became imbalanced at 2 years postoperatively.

CONCLUSION

Postoperative shoulder imbalance in this early group of patients with IS undergoing AVBT was seen in 16% of patients, a reduction from 30% preoperatively. These results likely reflect the potential of the proximal thoracic curve to correct spontaneously following AVBT.

LEVEL OF EVIDENCE

Level III.

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.

Sinister! The high pre-op left shoulder is less likely to be radiographically balanced at 2 years post-op

PURPOSE

AIS patients consider shoulder balance an important cosmetic outcome after surgery. We examined the impact of preoperative left shoulder elevation (LSE) and choice of upper instrumented vertebra (UIV) on postoperative shoulder imbalance (PostSI).

METHODS

This was a retrospective cohort study utilizing a prospective AIS database. Patients had Lenke type 1-4 curves and preoperative shoulder height ≥ 1.0 cm. Patients with preoperative LSE and right shoulder elevation (RSE) were compared. Shoulder height difference < 1 cm was considered 'mild', 1-2 cm was 'moderate', and ≥ 2.0 cm was 'severe'.

RESULTS

407 patients had ≥ 1.0 cm imbalance preoperatively, with 88 (21.6%) LSE. There were no differences in gender (p = 0.855) or age (p = 0.477). Patients with LSE more frequently had Lenke type 2 curves (43.2% vs 16.3%, p < 0.001), while preoperative RSE averaged 1.9 ± 0.9 cm versus 1.6 ± 0.5 cm for LSE (p < 0.001). Those with LSE more often had severe PostSI at 2 years (30.7% vs 5.0%, p < 0.001), and only 26.1% of patients with severe preoperative LSE corrected to mild. In contrast, most patients with RSE had mild PostSI regardless of initial imbalance. When examining only LSE patients, there was no difference in preoperative SH by final UIV (p = 0.101). Further, UIV choice did not impact the proportion of severely unbalanced patients postoperatively (p = 0.446). A PTC > 34.5° was predictive of PostSI ≥ 2.0 cm for patients with preoperative LSE.

CONCLUSION

AIS patients with preoperative LSE are less likely to achieve level shoulders postoperatively. Choice of higher UIV did not affect postoperative shoulder imbalance in this cohort. A PTC > 34.5° was predictive of severe PostSI in patients with preoperative LSE.

LEVEL OF EVIDENCE

II.

An analysis of preoperative shoulder and neck balance and surgical outcome in 111 adolescent idiopathic scoliosis patients with two subtypes of Lenke 1 curves

OBJECTIVE

The incidence of postoperative shoulder imbalance following posterior spinal fusion (PSF) is still high in Lenke 1 curves despite following current treatment recommendations for upper instrumented vertebra (UIV) selection. The objective of this retrospective study was to identify differences in preoperative shoulder balance and to report the surgical outcome of two subtypes of Lenke 1 curves (flexible vs stiff) in patients with adolescent idiopathic scoliosis (AIS).

METHODS

The authors grouped patients' curves as Lenke 1-ve (flexible) when their preoperative proximal thoracic side bending (PTSB) Cobb angle was < 15° and as Lenke 1+ve (stiff) when the PTSB Cobb angle was 15°-24.9°. The authors hypothesized that these two subtypes had distinct preoperative and postoperative shoulder and neck balance following PSF using pedicle screw constructs.

RESULTS

Fifty patients had Lenke 1 (flexible) curves and 61 had Lenke 1 (stiff) curves. The mean preoperative T1 tilt for patients with Lenke 1 (flexible) was -4.9° ± 5.3°, and for those with Lenke 1 (stiff) curves it was -1.0° ± 5.3° (p < 0.001). Mean cervical axis (CA) was -0.1° ± 3.2° for Lenke 1 (flexible) curves and 2.3° ± 3.5° for Lenke 1 (stiff) curves (p < 0.001). Preoperative radiographic shoulder height (RSH) and clavicle angle (Cla-A) were similar between the two curve subtypes. Following surgery, there were significant differences between the subtypes in terms of T1 tilt (p < 0.001), RSH (p = 0.014), and Cla-A (p = 0.031). Interestingly, 41.0% of patients with a Lenke 1 (stiff) curve had +ve T1 tilt compared to 2.0% in Lenke 1 (flexible) group. Moreover, 26.2% of patients with the Lenke 1 (stiff) curve had +ve RSH compared to 12.0% of those with Lenke 1 (flexible) curves. And, 24.6% of patients with Lenke 1 (stiff) had +ve Cla-A compared to 10.0% of those with Lenke 1 (flexible) curves.

CONCLUSIONS

Lenke 1 (flexible) and Lenke 1 (stiff) curves had distinct preoperative T1 tilt and CA measurements. Following PSF, the authors noted +ve T1 tilt in 41% of patients with Lenke 1 (stiff) curves versus 2.0% in those with Lenke 1 (flexible) curves. The authors also noted a significant difference in postoperative RSH and Cla-A measurements.

Selection of the Lowest Instrumented Vertebra and Relative Odds Ratio of Distal Adding-on for Lenke Type 1A and 2A Curves in Adolescent Idiopathic Scoliosis: A Systematic Review and Meta-analysis

Objective

To examine existing literature and pool the data to determine the relative odds ratio of “adding-on” (AO) based on various reported criteria for lower instrumented vertebra (LIV) selection in Lenke type 1A and 2A curves.

Methods

Using electronic databases, studies reporting on AO and LIV selection in Lenke type 1A and 2A curves were identified. Studies were excluded if they failed to meet the following criteria: ≥ 30 patients, Lenke type 1A or 2A curves, thoracic-only fusions, and inclusion of outcome differences in AO and non-AO groups. Review articles, letters, and case reports were excluded.

Results

Six studies were identified reporting on 732 patients with either Lenke type 1A or 2A curves treated with thoracic-only fusions. Five different landmarks were used for LIV selection in these studies including the stable vertebra (SV) -1, end vertebra (EV) +1, neutral vertebra (NV), touched vertebra (TV), and substantially touched vertebra (STV) versus nonsubstantially touched vertebra (nSTV) +1. The pooled odds ratios of AO for choosing LIV at levels above the afore landmarks (i.e., ending the construct “short”) versus at the landmarks were 2.59 (SV-1), 2.43 (EV+1), 3.05 (NV), 3.40 (TV), and 4.52 (STV/nSTV+1), all at 95% confidence interval.

Conclusion

Five landmarks shared a similar characteristic in that the incidence of AO was significantly higher if the LIV was proximal to the chosen landmark. In addition, choosing STV/(nSTV+1) as the LIV have the lowest absolute risk of AO and the greatest risk reduction. If additional levels were fused (i.e., LIV distal to the landmark), there was no statistically significant benefit in further reducing the risk of AO. Selection of the optimal LIV is a complex issue and spine surgeons must balance the risk of AO with the need for motion preservation in young patients.

Clinical and radiological factors associated with postoperative shoulder imbalance and correlation with patient-reported outcomes following scoliosis surgery

Background

Shoulder balance (SB) is an important cosmetic concern and is a determinant to assess outcomes following scoliosis surgery. Shoulder imbalance (SI) has been studied predominantly in idiopathic scoliosis with limited literature on other etiologies.

Purpose

To assess SB following scoliosis surgery and correlate SRS-30 self-image scores with radiological shoulder imbalance SI.

Methods

A retrospective analysis was performed for 43 patients undergoing scoliosis surgery with a minimum 2-year follow-up. Radiological SI was assessed by the coracoid height difference on whole spine standing radiographs at preoperative, 12-weeks postoperative and 2-year follow-up. The preoperative Cobb angle, postoperative Cobb angle and mean correction were recorded. The upper and lower end vertebrae (UEV/LEV), and instrumented vertebrae (UIV/LIV) were documented. The aetiology of scoliosis and functional outcomes based on the SRS-30 questionnaire were noted.

Results

There were 19 males and 24 females with a mean age of 14.5 ± 4.7 years. The 12-week postoperative radiographs showed SI in 15 patients and residual SI in 7 patients at 2-year follow-up. SI was seen in four congenital scoliosis with segmentation or mixed anomalies in the proximal thoracic spine. Two idiopathic scoliosis (Lenke type 1 and type 3) showed SI where the UIV was T3 and T2 respectively. The mean preoperative SRS-30 score for patients with SB (N = 9) was 2.5 ± 0.72 and for SI (N = 34) was 3 ± 0.42 without significant difference (p > 0.5). The final mean SRS-30 self-image score for patients with SB was 3.7 ± 0.54 and for patients with SI was 3.7 ± 0.53 without significant difference (p > 0.05).

Conclusion

Radiological SI assessed by coracoid height difference was not associated with a significant difference in SRS 30 scores preoperatively and at 2 year follow up. SI was seen with congenital scoliosis associated with segmentation and mixed anomalies of the proximal thoracic spine.

Excessive correction impacts postoperative shoulder imbalance in lenke type 5C adolescent idiopathic scoliosis

BACKGROUND

Postoperative shoulder imbalance (PSI) has a negative impact on the surgical outcomes of patients with adolescent idiopathic scoliosis. This study aimed to evaluate the risk factors of PSI in patients with Lenke type 5C curves.

METHODS

This study included 100 patients who underwent posterior correction surgery using pedicle screw constructs for Lenke type 5C curves. The mean age of the patients at surgery was 15.5 ± 2.3 years, and the mean follow-up period was 36.6 ± 15.0 months. The subjects were classified into the following two groups: PSI and non-PSI. Radiographic parameters, including the preoperative and 2-year postoperative coronal and sagittal profiles, were compared between the two groups.

RESULT

PSI was found in eight patients (8.0%). The preoperative Cobb angles were 47.3° ± 8.7° and 48.0° ± 3.9° in the non-PSI and PSI groups, respectively. The correction rate in the PSI group was significantly higher than that in the non-PSI group (81.0% ± 17.7% vs. 67.7% ± 14.7%; p = 0.018). The preoperative T1 tilt angle in the PSI group was significantly larger than that in the non-PSI group (6.1° ± 3.3° vs. 3.1° ± 2.8°; p = 0.005). Receiver operating characteristic (ROC) analysis showed that the area under the ROC curve was 0.769 (p = 0.012, 95% confidence interval [CI], 0.556-0.982) and 0.763 (p = 0.014, 95% CI, 0.598-0.928) for the correction rate and preoperative T1 tilt, respectively. The cut-off value was 73% and 4° for the correction rate and preoperative T1, respectively.

CONCLUSION

PSI was found in 8.0% of Lenke type 5C curves. Excessive correction of the lumbar curve of >73% and preoperative T1 tilt of >4° can be risk factors for PSI in patients with Lenke type 5C curve.

Anchor type at upper instrumented vertebra and postoperative shoulder imbalance in patients with Lenke type 1 adolescent idiopathic scoliosis

PURPOSE

To clarify the impact of anchor type at upper instrumented vertebra (UIV) on postoperative shoulder imbalance in patients with Lenke type 1 adolescent idiopathic scoliosis (AIS) who underwent posterior spinal fusion.

METHODS

Subjects were 81 patients with Lenke type 1 AIS who underwent posterior spinal fusion between 2004 and 2013. Twenty-five patients agreed to participate in the study. We divided the patients into two groups: Hook group (15 patients with hooks at UIV who underwent surgery between 2004 and 2011) and PS group (ten patients with pedicle screws at UIV who underwent surgery between 2012 and 2013). To evaluate shoulder balance, first thoracic vertebra tilt angle (T1 tilt), clavicle angle (CA), and radiographic shoulder height (RSH) were measured.

RESULTS

There were no significant differences in preoperative T1 tilt, CA, or RSH between the both groups. The postoperative 1-week, 2-year, and most recently observed T1 tilts were significantly smaller in the Hook group than in the PS group. There were no significant differences in postoperative 1-week, 2-year, and most recently observed CAs between the two groups. Although there were no significant differences in 1-week postoperative RSH between the groups, the 2-year postoperative RSH was significantly smaller in the Hook group than in the PS group. The most recently observed RSH tended to be smaller in the Hook group than in the PS group, but the difference was not significant.

CONCLUSIONS

In the PS group, poor shoulder balance remained over the long term. The hooks at UIV adjusted postoperative shoulder balance.

Conformity and Changes in the Radiological Neck and Shoulder Balance Parameters Throughout 3-Year Follow-up Period: Do They Remain the Same?

STUDY DESIGN

Retrospective study.

OBJECTIVE

The primary objective of this study was to assess the conformity of the radiological neck and shoulder balance parameters throughout a follow-up period of more than 2 years.

SUMMARY OF BACKGROUND DATA

Postoperative shoulder and neck imbalance are undesirable features among Adolescent Idiopathic Scoliosis patients who underwent Posterior Spinal Fusion. There are many clinical and radiological parameters used to assess this clinical outcome. However, we do not know whether these radiological parameters conform throughout the entire follow-up period.

METHODS

This was a retrospective study done in a single academic institution. Inclusion criteria were patients with scoliosis who underwent posterior instrumented spinal fusion with pedicle screw fixation and attended all scheduled follow-ups for at least 24 months postoperatively. Radiological shoulder parameters were measured from both preoperative antero-posterior and postoperative antero-posterior radiographs. Lateral shoulder parameters were: Radiographic Shoulder Height, Clavicle Angle (Cla-A), Clavicle-Rib Intersection Difference, and Coracoid Height Difference. Medial shoulder and neck parameters were: T1 Tilt and Cervical Axis (CA).

RESULTS

The radiographs of 50 patients who had surgery done from November 2013 to November 2015 were analyzed. Mean age of this cohort was 16.3 ± 7.0 years. There were 38 (76%) female patients and 12 (24%) male patients. Mean final follow-up was 38.6 ± 5.8 months. When conformity assessment of the radiological parameter using the interclass coefficient correlation was done, we found that all parameters had significant correlation (P < 0.05). T1 tilt (0.78) had good reliability, CA (0.47), Clavicle-Rib Intersection Difference (0.43), and Coracoid Height Difference (0.40) had moderate reliability and Radiographic Shoulder Height (0.22) and Cla-A (0.13) had poor reliability.

CONCLUSION

All the radiological shoulder and neck balance parameters studied were conformed and suitable to be used to assess the patient postoperatively. Amongst these radiological parameters, T1 tilt followed by CA recorded to be the most reliable parameters over time.

LEVEL OF EVIDENCE

4.

Hooks at the Upper Instrumented Vertebra Can Adjust Postoperative Shoulder Balance in Patients with Adolescent Idiopathic Scoliosis: 5 Years or More of Follow-up

Study Design

A retrospective cohort study.

Purpose

This study aims to investigate postoperative shoulder imbalance (PSI) ≥5 years postoperatively in patients who underwent posterior spinal fusion using hooks at the upper instrumented vertebra (UIV) for Lenke type 1 adolescent idiopathic scoliosis (AIS).

Overview of Literature

Studies have reported PSI due to excessive correction of the main thoracic curve.

Methods

We examined 56 patients with AIS who underwent a posterior spinal fusion with hooks at the UIV from 2004 to 2010. Of these, we enrolled 14 patients who underwent surgery, at least, 5 years ago. X-rays and Scoliosis Research Society-22 (SRS-22) questionnaire were administered. To evaluate the shoulder balance, T1 vertebral tilt angle (T1 tilt), clavicle angle, and radiographic shoulder height (RSH) were measured. PSI was considered as the absolute value of the postoperative RSH being ≥20 mm. Based on radiographs obtained immediately postoperatively, we divided patients into two groups as follows: the balanced group (absolute value of RSH <20 mm) and imbalanced group (absolute value of RSH ≥20 mm).

Results

The frequency of PSI was 28.6% immediately postoperatively, 0% 2 years postoperatively, and 7.1% at the last follow-up. In the balanced group, PSI did not occur even at 2 years postoperatively or at the last follow-up. In the imbalanced group, PSI was improved in all patients 2 years postoperatively and all patients, except one patient, at the last follow-up. No significant differences were noted in the frequency of distal adding-on at 2 years postoperatively or the last follow-up between the balanced group and the imbalanced group. We observed moderate negative correlations between the absolute value of T1 tilt and the SRS-22 pain and satisfaction at the last follow-up.

Conclusions

Hooks at the UIV could adjust the shoulder balance to avoid long-term PSI in patients with AIS.

In Search of the Ever-Elusive Postoperative Shoulder Balance: Is the T2 UIV the Key?

STUDY DESIGN

Multicenter review of prospectively collected data.

OBJECTIVE

The purpose of this study was to evaluate whether a UIV of T2 reliably results in level shoulders postoperatively.

SUMMARY OF BACKGROUND DATA

Adolescent idiopathic scoliosis (AIS) patients with a risk of a high left shoulder postoperatively are generally recommended to have instrumentation to T2, those with neutral shoulders a T3 UIV, and those with an elevated right shoulder are recommended a UIV of T4 or below in order to achieve postoperative shoulder balance.

METHODS

A prospective, multicenter AIS database was queried for subjects with minimum two-year follow-up who underwent posterior spinal fusion to correct their main thoracic deformity. Subjects were grouped based on their proximal fusion level. A high shoulder was defined as >1 cm difference on radiographs.

RESULTS

A total of 626 subjects met inclusion criteria and were divided by UIVs of T2 189, T3 205, and T4 232. Preoperatively, the groups had similar rates of balanced shoulders (T2 47%, T3 49%, T4 45%) and high left shoulders (T2 8.5%, T3 8.8%, and T4 7.3%). Postoperatively, there was a greater percentage of postoperative shoulder imbalance for T2 (45%) and T3 (48%) UIV groups as compared to T4 (34%, p = .008). As expected, the T2 (46%) and T3 (49%) groups had significantly better upper thoracic curve correction as compared to the T4 group (42%, p < .001).

CONCLUSIONS

The selection of a T4 UIV results in more shoulder balance postoperatively than T2 or T3, regardless of which shoulder was elevated preoperatively. The selection of a T2 UIV does not guarantee postoperative shoulder balance following posterior treatment of main thoracic curves; however, when compared to the more caudal UIV of T4, an improved upper thoracic curve correction can be anticipated.

LEVEL OF EVIDENCE

Level 3.

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.

Postoperative translation of the upper instrumented vertebra in thoracic adolescent idiopathic scoliosis

OBJECTIVEThe aim of this retrospective study was to analyze the influence of upper instrumented vertebra (UIV) translation from the C7 plumb line (C7PL) on the long-term postoperative results of patients with main thoracic (MT) adolescent idiopathic scoliosis (AIS).METHODSTwenty-five patients had been treated surgically for AIS with a Lenke type 1 curve and had been followed up for a mean period of 18.2 years. Radiographic parameters, pulmonary function measurements, and clinical outcomes were compared between the patients (n = 15) with UIV translation < 20 mm and those (n = 10) with UIV translation ≥ 20 mm at the final follow-up. Correlations between UIV translation and radiographic or pulmonary function parameters were analyzed.RESULTSPatients with ≥ 20 mm UIV translation at the final follow-up had a significantly larger preoperative UIV translation than that in the patients with < 20 mm UIV translation at follow-up. The former group also had a significantly lower correction rate of the MT curve, higher chest cage ratio, and lower radiographic shoulder height (p = 0.01, 0.005, and 0.025, respectively) at the final follow-up. The Scoliosis Research Society (SRS)-30 Questionnaire scores were equivalent between the two groups. Correlation analysis showed that the following parameters were significantly associated with UIV translation: MT curve correction rate (r = -0.481, p = 0.015), chest cage ratio (r = 0.673, p < 0.001), and percent-predicted forced expiratory volume in 1 second (r = -0.455, p = 0.033).CONCLUSIONSThe UIV translation should be considered an important factor that influences postoperative results. In MT AIS patients whose preoperative upper end vertebra (UEV) is distant from the C7PL, the UIV should be selected above the UEV to prevent large UIV translation at the postoperative follow-up.

Cervical Supine Side-Bending versus Cervical Supine Traction Radiographs: Which Is Better in Predicting Proximal Thoracic Flexibility for Lenke 1 and 2 Adolescent Idiopathic Scoliosis?

Study Design

Prospective cohort study.

Purpose

This study compared cervical supine side-bending (CSSB) and cervical supine traction (CST) radiographs to assess the flexibility and predict the correctability of the proximal thoracic (PT) curve for patients with adolescent idiopathic scoliosis (AIS) classified as Lenke 1 and 2.

Overview of Literature

Knowledge of the flexibility of the PT curve is crucial in the management of patients with AIS. There are no reports comparing CSSB and CST radiographs to assess this parameter.

Methods

Thirty patients with Lenke 1 and 2 AIS scheduled for posterior spinal fusion surgery were recruited. A standing whole spine radiography and physician-supervised CSSB and CST radiographies were performed. Patient demographic and radiological parameters were recorded, including age, gender, weight, height, body mass index, PT angle, main thoracic angle, CSSB PT angle, CST PT angle, and postoperative PT angle. From the data collected, the curve flexibility and curve correction index were calculated and compared.

Results

CSSB had a significantly (p <0.05) smaller PT angle (16.6°±10.4°) in comparison to CST (23.7°±10.7°). CSSB had significantly (p <0.05) greater flexibility (44.2%±19.7%) in comparison to CST (19.5%±18.1%). The CSSB correction index (1.2±0.9) was significantly closer to 1 in comparison to the CST correction index (4.4±5.3). There was no difference (p =0.72) between the CSSB PT angle (16.6°±10.4°) and the postoperative PT angle (16.1°±7.5°). However, the CST PT angle (23.7°±10.7°) was significantly (p <0.05) larger than the postoperative PT angle (16.1°±7.5°).

Conclusions

CSSB radiographs were better for demonstrating PT flexibility and more accurately predicted correctability in comparison to the CST radiographs.

Fulcrum flexibility of the main curve predicts postoperative shoulder imbalance in selective thoracic fusion of adolescent idiopathic scoliosis

PURPOSE

To identify preoperative predictors for postoperative shoulder imbalance (PSI) after corrective surgery of adolescent idiopathic scoliosis (AIS) and using the fulcrum-bending radiograph to assess flexibility.

METHODS

A consecutive surgical cohort of AIS patients undergoing selective thoracic fusion with alternate-level pedicle screw fixation was prospectively studied. Preoperative anteroposterior, lateral and fulcrum-bending radiographs were analysed. Postoperatively, a minimum of 2 years clinical and imaging follow-up was performed of all patients. PSI was defined as a radiographic shoulder height difference of more than 20 mm.

RESULTS

A total of 80 patients were included, and 14 patients (18%) were confirmed with PSI at final follow-up. The flexibility of MT curve was an independent risk factor for PSI (odds ratio (OR) = 3.3 per 10% decrease, 95% confidence interval (CI) 1.6-8.2). Twenty-seven patients had a preoperative MT flexibility of < 55% (OR = 11.5, 95% CI 2.8-46.2). Postoperative T1 tilt was significantly higher in the PSI group (p < 0.001), and a T1 tilt of more than 9° resulted in 7.2 times higher odds of developing PSI (95% CI 2.0-26.0). Fulcrum-bending correction index (FBCI) was significantly higher in the PSI group at final follow-up, and 25 patients had a final postoperative MT FBCI above 120% (OR = 8.5 (95% CI 2.3-31.0).

CONCLUSIONS

A low preoperative curve flexibility is a significant predictor for PSI. The surgical strategy should consider proximal fusion in presence of low-flexibility MT curves and consider less aggressive MT curve correction. Achieving a level T1 should be a main priority during intraoperative correction and may require fusion of the PT curve.

LEVEL OF EVIDENCE

III. These slides can be retrieved under Electronic Supplementary Material.

Prevalence, Risk Factors, and Characteristics of the "Adding-On" Phenomenon in Idiopathic Scoliosis After Correction Surgery: A Systematic Review and Meta-Analysis

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVE

To discuss the prevalence, risk factors, and characteristics of the "adding-on" phenomenon in idiopathic scoliosis (IS).

SUMMARY OF BACKGROUND DATA

There are controversies on the prevalence and risk factors of the "adding-on" phenomenon. In addition, there is no comprehensive study to describe the characteristics of "adding-on" in IS patients.

METHODS

We performed a systematic online search using PubMed, EMBASE, Web of Science, the Cochrane Library, and China WeiPu Library to identify eligible studies. Effect size (ES), odds ratios (OR), and weight mean difference (WMD) with 95% confidence interval (CI) were used to evaluate the incidence, characteristics, and risk factors for "adding-on," respectively.

RESULTS

The overall pooled prevalence of "adding-on" was 14%. Subgroup analysis showed that the prevalence of "adding-on" in Lenke 1A adolescent idiopathic scoliosis (AIS), Lenke 2 AIS, Lenke 5 AIS, and mixed AIS was 15%, 12%, 9%, and 16%, respectively. AIS patients with the "adding-on" phenomenon had smaller proximal thoracic curve (PTC), main thoracic curve (MTC), clavicle angle, T1 tilt angle and radiographic shoulder height (RSH), and larger correction of PTC. Age, Risser sign, preoperative PTC, preoperative MTC, preoperative lumbar curve (LC), preoperative coronal balance and sagittal balance, and T4 tile were identified as risk factors of "adding-on." Selection of lower instrumented vertebra (LIV) was also an important risk factor as LIV-Center Sacral Vertical Line (CSVL), LIV-end vertebra, LIV-Stable Vertebra, and LIV-Neutral vertebra, and deviation of LIV+1 was found to be significantly associated with "adding-on." Besides, postoperative MTC was also significantly different between patients with and without "adding-on."

CONCLUSION

The pooled prevalence varied differently in different types of IS. Patients with "adding-on" had smaller PTC, MTC, angle, T1 tilt angle and RSH, and larger correction of PTC. Younger age, less skeletal maturity, smaller preoperative PTC, smaller preoperative MTC, smaller preoperative LC, larger preoperative coronal, sagittal imbalance, selection of LIV, and overcorrection of coronal and sagittal alignment were risk factors for "adding-on."

LEVEL OF EVIDENCE

4.

Selecting the LSTV as the Lower Instrumented Vertebra in the Treatment of Lenke Types 1A and 2A Adolescent Idiopathic Scoliosis: A Minimal 3-year Follow-up

STUDY DESIGN

Retrospective study.

OBJECTIVE

The purpose of this study was to verify the last substantially touched vertebra (LSTV) as the ideal lower instrumented vertebra (LIV) and to identify predictive factors of adding-on in patients with Lenke type 1A and 2A curve patterns when LSTV was chosen as the LIV.

SUMMARY OF BACKGROUND DATA

Although several studies have indicated that the use of the LSTV as the LIV can obtain favorable outcomes in Lenke 1A and 2A curves, the factors identifying patients with Lenke 1A and 2A curve patterns who should undergo a fusion extending beyond the LSTV have not been identified.

METHODS

A total of 120 patients with Lenke 1 and 2 curves after posterior instrumentation and fusion to the LSTV were evaluated. All patients had a minimum 3-year follow-up. Patients were grouped based on the occurrence of the distal adding-on phenomenon: an adding-on group and a no adding-on group. We analyzed the significant independent factors associated with adding-on via univariate analysis and then via stepwise logistic regression analysis.

RESULTS

Distal adding-on was observed in 16 patients (13.33%). Binary logistic regression analysis showed that the Risser sign (OR = 0.592, P = 0.033), preoperative distance between the LIV and the center sacral vertical line (CSVL) (LIV-CSVL) (OR = 1.286, P = 0.002), and postoperative thoracic kyphosis (T5-T12) (OR = 0.784, P = 0.002) were primary factors for distal adding-on.

CONCLUSION

Selecting the LSTV as the LIV simplifies the selection of the LIV and is an effective operation strategy in patients with Lenke 1A and 2A curve types. Patients with lower Risser sign, larger preoperative LIV-CSVL, and postoperative thoracic hypokyphosis are more likely to develop distal adding-on at 3-year follow-up.

LEVEL OF EVIDENCE

4.

The effects of scoliosis and subsequent surgery on the shape of the torso

Background

Adolescent idiopathic scoliosis (AIS) causes asymmetry of the torso, and this is often the primary concern of patients. Surgery aims to minimise the visual asymmetry. It is not clear how scoliosis makes the torso asymmetric or how scoliosis surgery changes that asymmetry when compared to the distribution of asymmetries seen in a non-scoliotic group of normal controls.

Methods

Surface topography images were captured for a group with AIS both pre-operatively and post-operatively. Identifiable points were compared between the images to identify the effects of AIS on the shape of the torso by looking at the relative heights and distances from the midline of the shoulders, axillae and waist in a two-dimensional coronal view. This was then compared to a previously reported group of normal non-scoliotic children to analyse whether surgery recreated normality.

Results

There were 172 pairs of images with 164 females and 8 males, mean age at pre-operative scan of 13.7 years. The normal group was 642 images (237 females and 405 males) from 116 males and 79 females, mean age of 12.5 years.

The curve patterns seen in the scoliotic group matched the patterns of a main thoracic curve (n = 146) and main thoracolumbar curve (n = 26). The asymmetries seen in both shoulders, axillae and waist were different between the two different types of curve. Across both groups, the shoulder asymmetry was less than that of the corresponding axillae.

There was a statistically significant reduction in all asymmetries following surgery in the main thoracic group (p < 0.001). This was not seen in the main thoracolumbar group, thought to be due to the small sample size. In the main thoracic group, there were statistically significant differences in the asymmetries between the post-operative and normal groups in the shoulders and axillae (p < 0.001) but not the waist.

Conclusions

This paper demonstrates quantitatively the range of asymmetries seen in the AIS torso and the degree to which surgery alters them. Surgery does not recreate normality but does cause a statistically significant change in torso shape towards that seen in a non-scoliotic group.

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

BACKGROUND CONTEXT

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

PURPOSE

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

STUDY DESIGN

This study is a narrative review.

METHODS

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

RESULTS

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

CONCLUSIONS

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

A retrospective study to reveal factors associated with postoperative shoulder imbalance in patients with adolescent idiopathic scoliosis with double thoracic curve

OBJECTIVE Postoperative shoulder imbalance (PSI) is a critical consideration after corrective surgery for a double thoracic curve (Lenke Type 2); however, the radiographic factors related to PSI remain unclear. The purpose of this study was to identify the radiographic factors related to PSI after corrective surgery for adolescent idiopathic scoliosis (AIS) in patients with a double thoracic curve. METHODS This study included 80 patients with Lenke Type 2 AIS who underwent corrective surgery. Patients were grouped according to the presence [PSI(+)] or absence [PSI(-)] of shoulder imbalance at the final follow-up examination (differences of 20, 15, and 10 mm were used). Various radiographic parameters, including the Cobb angle of the proximal and middle thoracic curves (PTC and MTC), radiographic shoulder height (RSH), clavicle angle, T-1 tilt, trunk shift, and proximal and distal wedge angles (PWA and DWA), were assessed before and after surgery and compared between groups. RESULTS Overall, postoperative RSH decreased with time in the PSI(-) group but not in the PSI(+) group. Statistical analyses revealed that the preoperative Risser grade (p = 0.048), postoperative PWA (p = 0.028), and postoperative PTC/MTC ratio (p = 0.011) correlated with PSI. Presence of the adding-on phenomenon was also correlated with PSI, although this result was not statistically significant (p = 0.089). CONCLUSIONS Postoperative shoulder imbalance is common after corrective surgery for Lenke Type 2 AIS and correlates with a higher Risser grade, a larger postoperative PWA, and a higher postoperative PTC/MTC ratio. Presence of the distal adding-on phenomenon is associated with an increased PSI trend, although this result was not statistically significant. However, preoperative factors other than the Risser grade that affect the development of PSI were not identified by the study. Additional studies are required to reveal the risk factors for the development of PSI.

Assessing the Flexibility of the Proximal Thoracic Segments Above the "Potential Upper Instrumented Vertebra" Using the Cervical Supine Side Bending Radiographs in Lenke 1 and 2 Curves for Adolescent Idiopathic Scoliosis Patients

STUDY DESIGN

A prospective study.

OBJECTIVE

The aim of this study was to analyze the proximal thoracic (PT) flexibility and its compensatory ability above the "potential UIV."

SUMMARY OF BACKGROUND DATA

Shoulder and neck imbalance can be caused by overcorrection of the main thoracic (MT) curve due to inability of PT segment to compensate.

METHODS

Cervical supine side bending (CSB) radiographs of 100 Lenke 1 and 2 patients were studied. We further stratified Lenke 1 curves into Lenke 1-ve: PT side bending (PTSB) < 15° (n = 33) and Lenke 1+ve: PTSB 15° to 24.9° (n = 37). The right side bending (RSB) and left side bending (LSB) angles were measured (T1-T6). Compensatory ability of the PT segment was analyzed with assumption of a "horizontal UIV" position.

RESULTS

From T1 to T6 vertebrae, the RSB angle values showed increasing positive values. The LSB angle, comparing Lenke 1-ve versus 2 and Lenke 1+ve versus 2, showed significant difference at T2 to T6. The LSB angle comparing Lenke 1-ve versus 1+ve achieved significant difference at T5 and T6. In Lenke 2 curves, >80.0% of cases of the PT segment were unable to compensate at T3-T6. In Lenke 1+ve curves, 78.4% were unable to compensate at T6, followed by T5 (75.7%), T4 (73.0%), T3 (59.5%), T2 (27.0%), and T1 (21.6%). In Lenke 1-ve curves, 36.4% of cases were unable to compensate at T6, followed by T5 (45.5%), T4 (45.5%), T3 (30.3%), T2 (21.2%), and T1 (15.2%). A significant difference between Lenke 1-ve and Lenke 1+ve was observed from T3 to T6. The difference between Lenke 1+ve and Lenke 2 curves was significant only at T2.

CONCLUSION

The compensation ability and the flexibility of the PT segments of Lenke 1-ve and Lenke 1+ve curves were different. Lenke 1+ve curves demonstrated similar characteristics to Lenke 2 curves.

LEVEL OF EVIDENCE

3.

Adding-on Phenomenon After Surgery in Lenke Type 1, 2 Adolescent Idiopathic Scoliosis: Is it Predictable?

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to detect risk factors for Adding-on after posterior correction surgery in patients with Lenke 1 or 2 AIS, and to explore whether Adding-on Index could be used to predict Adding-on effectively.

SUMMARY OF BACKGROUND DATA

Adding-on phenomenon is a common complication in Lenke 1 or 2 AIS patients after correction surgery. However, whether it can be predicted after surgery remains unknown.

METHODS

Lenke 1 or 2 AIS patients receiving correction surgery in our center from January 2009 to July 2013 were analyzed. Antero-posterior and lateral films were evaluated before surgery, at 2 weeks' and 2 years' follow-up. Patients were divided into 2 groups according to whether Adding-on occurred at the 2 years' follow-up. Risk factors of Adding-on were analyzed, and Adding-on Index was proposed and verified.

RESULTS

Sixteen patients (16.3%) suffered from distal Adding-on at 2-year follow-up. Several parameters were found to be significantly different between 2 groups, including Risser's sign, postoperative Cobb angle of main thoracic, postoperative Cobb angle of main thoracic curve at 2-year follow-up, preoperative and postoperative Cobb angle of lumbar curve, postoperative Cobb angle of lumbar curve at 2-year follow-up, LIV-EV, LIV-SV, LIV-CSVL, LAV-CSVL, LAV-LIV, DnfS, and postoperative TJK. No significant differences in SRS-22 scores were observed. Binary logistic regression analysis showed that DnfS and postoperative residual Cobb angle of lumbar curve were primary factors for occurrence of Adding-on. According to the regression equation, Adding-on Index was defined as 4 × DnfS-postoperative lumbar curves Cobb angle. On the basis of ROC curve, if Adding-on Index was more than 12, the occurrence rate of Adding-on was 88%. On the contrary, the rate of no Adding-on phenomenon was 80%.

CONCLUSION

DnfS and posterior Cobb angle of lumbar curve were 2 important factors for Adding-on in Lenke 1, 2 AIS patients. Adding-on Index can be used to predict the occurrence of Adding-on effectively.

LEVEL OF EVIDENCE

4.

Evaluation of the predictors of postoperative aggravation of shoulder imbalance in severe and rigid thoracic or thoracolumbar scoliosis

OBJECTIVE

To study the predictors of postoperative aggravation of shoulder imbalance in severe and rigid thoracic or thoracolumbar scoliosis.

METHODS

In this study, 49 patients with severe and rigid thoracic or thoracolumbar scoliosis were analyzed retrospectively. The patients underwent whole-spine anteroposterior and lateral radiography preoperatively and postoperatively. On the radiographs, we measured parameters, including T1 tilt, radiographic shoulder height (RSH), proximal curve, middle curve, distal curve, apical vertebral translation (AVT) of the middle curve, thoracic trunk shift (TTS), coronal balance, and sagittal balance. We regarded RSH and T1 tilt as postoperative shoulder balance parameters and divided the patients into improved and aggravated groups of shoulder imbalance. Univariate analysis, receiver operating characteristic (ROC) curve, and multivariate logistic regression analyses were used in the statistical analyses.

RESULTS

The RSH was -17.01 ± 21.85 mm before surgery and 4.76 ± 18.11 mm at follow-up. The T1 tilt angle was -10.20° ± 19.53° before surgery and -2.72° ± 13.48° at follow-up. The results of the univariate analysis suggest that preoperative RSH and proximal to middle curve change ratio were significantly higher in the patients in the improved RSH group (p < 0.01). In addition, preoperative RSH, preoperative T1 tilt, and apical vertebral translation of the middle curve were significantly higher, and preoperative proximal curve, postoperative proximal curve, and preoperative distal curve were significantly lower in the patients with improved T1 tilt group (p < 0.01). In a binary logistic regression analysis, preoperative RSH [B = -0.120, odds ratio (OR) = 0.887, p = 0.006] was found to be an independent predictor of postoperative aggravation of RSH. Similarly, preoperative T1 tilt (B = -0.488, OR = 0.614, p = 0.001) was found to be an independent predictor of postoperative aggravation of T1 tilt. Moreover, the relationship between changes in RSH and T1 tilt was either concordant or discordant.

CONCLUSION

Several radiographic parameters were found to affect postoperative aggravation of RSH and T1 tilt. In particular, preoperative RSH and T1 tilt were found to be independent predictive factors of postoperative aggravation of RSH and T1 tilt, respectively.