T1 Tilt Research Articles

EARLY CHANGES IN SHOULDER BALANCE AFTER SELECTIVE ANTERIOR CORRECTION AND FUSION FOR LUMBAR SCOLIOSIS

Some patients developed shoulder imbalance after selective anterior correction of lumbar scoliosis with spontaneous rebalances later on. We conducted this retrospective radiographic analysis study to study the effect of selective anterior correction of thoracolumbar and lumbar scoliosis on shoulder balance. Standing X-ray films of 15 patients with lumbar scoliosis operated by anterior correction at preoperative, 3, 6 & 12 months postoperative were used. Spine and shoulder balance parameters were measured. Correlations between changes in shoulder balance and spine parameters were evaluated. Shoulder height parameters showed early postoperative change from positive or neutral to negative shoulder balance, Lumbar and thoracic Cobb angles showed immediate postoperative improvement with a slight later increase contributing to shoulder rebalance mechanisms. Changes in T1 tilt was correlated to change in thoracic Cobb angle at 3 months post op. (r= 0.515 p =.049), CRCI was correlated to difference between changes in lumbar Cobb angle and changes in thoracic Cobb angle (r= 0.56 p= 0.030), close correlation between Correction change ratio and T1 tilt, FRA, CA and CPH was shown (p=0.008, 0.016, 0.011 & 0.012). Spontaneous Correction of shoulder balance after anterior correction of lumbar scoliosis is likely to occur during the first postoperative year. Flexibility of the thoracic curve was a major determinant in the shoulder re-balance, ratio between correction of lumbar curve and correction of thoracic curve may have a prognostic value in shoulder rebalance after anterior correction surgery. Clavicle angle has the best predictor for postoperative shoulder balance improvement.

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

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). 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. 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. 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.

Risk factors for postoperative coronal decompensation in adult lumbar scoliosis after posterior correction with osteotomy.

To determine potential risk factors for postoperative coronal imbalance following posterior osteotomy for adult scoliosis. A total of 74 patients underwent osteotomy for rigid adult lumbar scoliosis. A group of 20 patients with postoperative coronal imbalance was identified. Clinical data and surgical strategies were compared to determine the risk factors, including age, gender, etiology, Cobb angle, preoperative coronal balance distance, direction of preoperative imbalance, T1 tilt, tilt of upper instrumented vertebra (UIV), UIV translation, location of UIV (T6 above or below), fusion to L5 or S1, lower instrumented vertebra (LIV) tilt, LIV rotation, screw density, osteotomy procedure (PSO or SPOs) and use of iliac screws. Comparison between patients with and without postoperative coronal imbalance showed that postoperative coronal imbalance occurred in older patients and those with degenerative scoliosis as the etiology, UIV above T6, preoperative LIV rotation, preoperative LIV tilt and preoperative coronal imbalance towards the convex side and who underwent Smith-Petersen osteotomy. All seven parameters were included in the logistic regression analysis. UIV above T6 (P = 0.010), LIV rotation (P = 0.012) and preoperative coronal imbalance towards the convex side (P = 0.005) were identified as risk factors for postoperative coronal imbalance after osteotomy. Patients with preoperative coronal imbalance towards the convex side (UIV above T6) and LIV rotation were more likely to develop coronal imbalance than those without risk factors. Older patients and those with degenerative scoliosis were also at a relatively higher risk of postoperative coronal imbalance.

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

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). 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. 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. 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.

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

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

The amount of surgical correction of the main thoracic curve is the best predictor of postoperative clinical shoulder balance in patients with Adolescent Idiopathic Scoliosis.

This study sought to analyze factors that predict postoperative shoulder balance based on clinical photography. Based on inclusion criteria, 132 AIS patients were selected. Age, sex, and BMI of each patient were recorded. The following parameters were recorded from radiographs: clavicle angle, T1 tilt, the upper instrumented vertebra (UIV), lowest instrumented vertebra (LIV) thoracic kyphosis, lumbar modifier, preoperative and postoperative proximal thoracic Cobb angle, preoperative and postoperative main thoracic Cobb angle, and preoperative and postoperative thoracolumbar Cobb angle, if applicable. Two spine surgeons independently assigned the photographs shoulder balance grades based on the WRVAS (1-2 = Acceptable, 3-5 = Unacceptable). Surgeons were blinded as to whether the photographs were taken preoperatively or postoperatively. The shoulders were also graded as right high, left high, or balanced. Of all variables analyzed, only main thoracic Cobb angle correction (MTCAC) showed a statistically significant relationship with postoperative shoulder balance (p = 0.01). Odds of having unacceptable shoulder balance increase by 21% for every 5° increase in MTCAC (Adjusted OR = 1.21, 95% CI 1.015-1.452). The odds of unbalanced shoulders are 4.7 times higher for patients whose MTCAC is 40° or more (p = 0.001). Inter-rater reliability was excellent (k =0 .7). Intra rater reliability was perfect for Surgeon 1 (kappa = 1.0) and showed substantial agreement for Surgeon 2 (kappa = 0.8) CONCLUSIONS: Greater correction of main thoracic Cobb angle predicts unacceptable postoperative shoulder balance with 40° of correction signifying a major dichotomy between acceptable and unacceptable.

Deformity correction using proximal hooks and distal screws (PHDSs) improves radiological metrics in adolescent idiopathic scoliosis.

Surgical correction for AIS has evolved from all hooks to hybrids or all screw constructs. Limited literature exists reporting outcomes using PHDS for posterior spinal fusion (PSF). This is the largestseries in evaluating results of PHDS technique. A retrospective review of consecutive AIS patients undergoing PSF by a single surgeon between 2006 and 2015 was performed. All eligible patients met a minimum 2-year follow-up. Patient demographics and radiographical parameters (radiographic shoulder height (RSH), T1 tilt, clavicle angle) at baseline, 6-week and 2-year post-operation were recorded. The primary outcome was difference in RSH from baseline measurements evaluated using repeated measures one-way analysis of variance with Bonferroni correction. A total of 219 patients (mean age at surgery: 13.68years; 82% female) were included. The mean follow-up was 41.2months (range 24-108months). The RSH was significantly improved from -14.7±10.38mm to 8.0±6.9mm (P < 0.0001). Clavicle angle was improved from 2.13° to 1.31° (P < 0.0001). T1 tilt was improved from 5.6° to 2.2° (P < 0.0001). At last follow-up, 95.8% of patients were shoulder balanced. There was a significant improvement of Cobb angle with an average correction of the upper thoracic curve of 42% and mainthoracic curve of 67%. The PHDS demonstrates the potential for additional shoulder balance improvement. Extension of fusion to structuralproximal thoracic spine is the key to success for shoulder balance. It remains to be seen whether these improvements will translate into improved clinical outcomes in the longer term.

Neutral cervical sagittal vertical axis and cervical lordosis vary with T1 tilt.

The authors conducted a study to determine whether a change in T1 tilt results in a compensatory change in the cervical sagittal vertical axis (SVA) in a cadaveric spine model. Six fresh-frozen cadavers (occiput [C0]-T1) were cleaned of soft tissue and mounted on a customized test apparatus. A 5-kg mass was applied to simulate head weight. Infrared fiducials were used to track segmental motion. The occiput was constrained to maintain horizontal gaze, and the mounting platform was angled to change T1 tilt. The SVA was altered by translating the upper (occipital) platform in the anterior-posterior plane. Neutral SVA was defined by the lowest flexion-extension moment at T1 and recorded for each T1 tilt. Lordosis was measured at C0-C2, C2-7, and C0-C7. Neutral SVA was positively correlated with T1 tilt in all specimens. After increasing T1 tilt by a mean of 8.3° ± 2.2°, neutral SVA increased by 27.3 ± 18.6 mm. When T1 tilt was reduced by 6.7° ± 1.4°, neutral SVA decreased by a mean of 26.1 ± 17.6 mm.When T1 tilt was increased, overall (C0-C7) lordosis at the neutral SVA increased from 23.1° ± 2.6° to 32.2° ± 4.4° (p < 0.01). When the T1 tilt decreased, C0-C7 lordosis at the neutral SVA decreased to 15.6° ± 3.1° (p < 0.01). C0-C2 lordosis increased from 12.9° ± 9.3° to 29.1° ± 5.0° with increased T1 tilt and decreased to -4.3° ± 6.8° with decreased T1 tilt (p = 0.047 and p = 0.041, respectively). Neutral SVA is not a fixed property but, rather, is positively correlated with T1 tilt in all specimens. Overall lordosis and C0-C2 lordosis increased when T1 tilt was increased from baseline, and vice versa.

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

Retrospective study. 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. 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. 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). 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. 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. 4.

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

Case-control study. 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. 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. 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°). 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. 3.

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.

Retrospective study. To investigate the relationship between a +ve postoperative Upper Instrumented Vertebra (UIV) (≥0°) tilt angle and the risk of medial shoulder/neck and lateral shoulder imbalance among Lenke 1 and 2 Adolescent Idiopathic Scoliosis (AIS) patients following Posterior Spinal Fusion. Current UIV selection strategy has poor correlation with postoperative shoulder balance. The relationship between a +ve postoperative UIV tilt angle and the risk of postoperative shoulder and neck imbalance was unknown. One hundred thirty-six Lenke 1 and 2 AIS patients with minimum 2 years follow-up were recruited. For medial shoulder and neck balance, patients were categorized into positive (+ve) imbalance (≥+4°), balanced, or negative (-ve) imbalance (≤-4°) groups based on T1 tilt angle/Cervical Axis measurement. For lateral shoulder balance, patients were classified into +ve imbalance (≥+3°) balanced, and -ve imbalance (≤-3°) groups based on Clavicle Angle (Cla-A) measurement. Linear regression analysis identified the predictive factors for shoulder/neck imbalance. Logistic regression analysis calculated the odds ratio of shoulder/neck imbalance for patients with +ve postoperative UIV tilt angle. Postoperative UIV tilt angle and preoperative T1 tilt angle were predictive of +ve medial shoulder imbalance. Postoperative UIV tilt angle and postoperative PT correction were predictive of +ve neck imbalance. Approximately 51.6% of patients with +ve medial shoulder imbalance had +ve postoperative UIV tilt angle. Patients with +ve postoperative UIV tilt angle had 14.9 times increased odds of developing +ve medial shoulder imbalance and 3.3 times increased odds of developing +ve neck imbalance. Postoperative UIV tilt angle did not predict lateral shoulder imbalance. Patients with +ve postoperative UIV tilt angle had 14.9 times increased odds of developing +ve medial shoulder imbalance (T1 tilt angle ≥+4°) and 3.3 times increased odds of developing +ve neck imbalance (cervical axis ≥+4°). 4.

Pedicle screw instrumentation with or without pelvic fixation in neuromuscular scoliosis: Outcome and complications in a series of 37 patients with a minimum 2-year follow-up

ObjectiveNeuromuscular scoliosis (NMS) is often associated with rapid progressive spinal deformities. Indications, when to extend the instrumentation to the pelvis for pelvic obliquity are not generally accepted at this time. This study reports on the indications, surgical technique and results using pedicle screw instrumentation exclusively with or without pelvic fixation for spine fusion in patients with NMS. Patients and methodsThirty-seven NMS patients were treated with pedicle screw instrumentation (PSI) between 2007 and 2013 with a minimum follow-up of 24 months. The mean age at the time of operation was 14.91 ± 2.03 years (range, 11.17–18.58). Posterior spine fusion (PSF) was conducted in 33 patients; 4 patients underwent a combined anterior spinal release followed by PSF during one-stage surgery. Pelvic fixation was achieved by ilium screws combined with S-1 screws in 4 cases and by sacral-alar-iliac (SAI) technique by Sponseller in 9 cases, respectively. ResultsThe mean primary Cobb angle was 65.5° (range, 14–103°) and improved significantly to 19.8° (range, 1–50°, p < 0.001) after surgery and 20.5° (range, 3–57, p = 0.47) at 2 years FU, respectively. Besides, an improvement of pelvic obliquity and T1 tilt angle could be detected. Major complications occurred in 19% and minor complications in 32%. ConclusionPedicle screw fixation only for spine fusion in patients with NMS can be applied safely with reasonable complication rates. An excellent correction in all planes, a significant improvement of the pelvic obliquity and almost no loss of correction at 2 years FU were observed.

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

BackgroundPostoperative 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. MethodsThis 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. ResultPSI 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. ConclusionPSI 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.

Impact of cervical range of motion on the global spinal alignment in ankylosing spondylitis patients with thoracolumbar kyphosis following pedicle subtraction osteotomy

BACKGROUND CONTEXTThe head's center of gravity (COG) plumb line (PL) and C7 PL could be simultaneously positioned over the pelvis in adult spinal deformity with normal cervical mobility. However, the position of the head in relation to the global spinal alignment has yet to be investigated in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis. PURPOSEThe objective of this study was to analyze the position of head in relation to the global spinal alignment in AS-related thoracolumbar kyphosis. STUDY DESIGN/SETTINGRetrospective single-center study. PATIENT SAMPLEAS patients who underwent lumbar pedicle subtraction osteotomy for thoracolumbar kyphosis from January 2010 to August 2016 were reviewed. Only patients with a visible ear canal on the preoperative, immediate postoperative, and final follow-up radiographs were included. OUTCOME MEASURESThe chin-brow angle, cervical range of motion (ROM), lumbar lordosis (LL), thoracolumbar angle, thoracic kyphosis (TK), L1 pelvic angle, pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), TK+LL+PI, PI-LL, maximal kyphosis (MK), deformity angular rate, T1 pelvic angle, T1 tilt, spinosacral angle, sagittal vertical axis (SVA) COG-C7, SVA COG-femoral head (FH), and SVA C7-S were evaluated. Data regarding the health-related quality of life, including the Oswestry disability index (ODI) and visual analogue scale (VAS)-back score, were also collected preoperatively, 2 years postoperatively, and at the latest follow-up. METHODSThe cohort was divided into patients with occiput-trunk (OT) concordance or with OT discordance according to the SVA COG-C7 ≤30 mm or >30 mm, respectively. There was no funding in this study and there are no conflict of interest-associated biases. RESULTSA total of 43 patients (36 males and 7 females) with a mean age of 34.2 years (range, 18–59 years) were identified. There were 17 patients accompanied with OT concordance and 26 patients with OT discordance preoperatively. The cervical ROM was significantly lower (24.0° vs 56.1°, p<.001) and SVA COG-C7 was significantly larger (71.7 mm vs 7.4 mm, p<.001) in patients with OT discordance. Furthermore, the PT was larger (41.0° vs 33.5°, p=.010) in patients with OT discordance. After surgery, the whole cohort showed an improvement in LL (−8.6° vs −52.8°, p<.001). Moreover, the CBVA (25.4° vs 1.3°, p<.001) and SVA COG-C7 (46.2 mm vs 21.6 mm, p<.001) were significantly decreased following lumbar PSO. There were 13 patients accompanied with OT discordance postoperatively, and the cervical ROM was still lower (22.5° vs 42.8°, p=.024) in these patients. Postoperative PT was larger (26.5° vs 20.1°, p=.033) in the patients with OT discordance. At the latest follow-up, there were 17 patients accompanied with OT discordance. In these 17 patients, the cervical ROM was significantly lower (21.0° vs 47.0°, p=.001) and PT was significantly higher (26.2° vs 19.2°, p=.012). The ODI and VAS-back scores demonstrated no significant differences between the two groups preoperatively, 2 years postoperatively, or at the latest follow-up. CONCLUSIONSOT discordance in AS-related thoracolumbar kyphosis could be caused by the reduced cervical ROM. To maintain global spinal balance, the pelvis rotated further backward in response to the larger SVA COG-C7. Moreover, the larger SVA COG-C7 could be decreased after the lumbar PSO. Although there were radiographic differences between the patients with OT concordance and with OT discordance, there was no difference in clinical outcomes, and that a larger sample size and longer follow-up are needed.

Postoperative neck tilt in Lenke 1 and 2 AIS patients after correction surgery: a novel predictive index

BackgroundPostoperative neck tilt (PNT) is a phenomenon in adolescent idiopathic scoliosis (AIS) patients which is distinct form shoulder imbalance. There were scarce studies performed to explore the risk factors for PNT in Lenke 1 and 2 AIS patients, and whether it can be predicted after surgery remains unknown. The objective of this study is to explore the prevalence and risk factors for PNT, and introduce an index for prediction of PNT in Lenke 1 and 2 AIS patients after correction surgery.MethodsMedical records of Lenke 1 and 2 AIS patients who received correction surgery were reviewed from February 2013 to February 2015. Posteroanterior films were evaluated before surgery and at 2 years’ follow-up. Patients were divided into two groups according to whether PNT occurred at the 2 years’ follow-up. Risk factors of PNT were analyzed, and PNT Index was proposed and verified.ResultsOne hundred two Lenke 1 and 2 AIS patients were recruited in this study. The prevalence of PNT after correction was 40.2%. According to the postoperative CAT (Cervical Axis Tilt), patients were divided into two group: PNT group (CAT≧5°, n = 41) and non-PNT group (CAT< 5°, n = 61). Postoperative T1 tilt, preoperative proximal thoracic curve (PTC), postoperative PTC and postoperative coronal balance (CB) were significantly different between two groups. Logistic regression showed that postoperative PTC and postoperative CB were the primary risk factors for PNT, which could be predicted by the regression equation: PNT Index = 1.1 x postoperative PTC (degrees) - 0.9 x postoperative CB (millimeters). On the basis of ROC curve, if PNT Index was more than 10, the occurrence rate of PNT was 86%. On the contrary, the rate of no PNT phenomenon was 80%.ConclusionPostoperative PTC and postoperative CB were the important factors for PNT in Lenke 1 and 2 AIS patients. Sufficient correction of PTC and moderate correction of CB should be recommended when operating on Lenke1 and 2 AIS patients.

135. Neutral cervical sagittal vertical axis (SVA) varies with T1 tilt

BACKGROUND CONTEXT With an aging population and increasing incidence of cervical spine surgery, more attention is being focused on cervical alignment and deformity. Iatrogenic deformity can result from under- or overcorrection of cervical sagittal alignment during fusion surgery. We sought to explore the relationship between T1 tilt and cervical SVA. In our cadaveric study, the sagittal vertical alignment (SVA) was altered for a given T1 tilt until the least extrinsic force was required to maintain alignment. This correlates with the in vivo state requiring the least muscle contraction to maintain alignment. PURPOSE To determine if an increase or decrease in T1 tilt from baseline will require a compensatory increase or decrease in SVA in order to maintain neutral posture. STUDY DESIGN/SETTING Cadaver biomechanical study. PATIENT SAMPLE Six cadaveric cervical spines (occiput-T1). OUTCOME MEASURES C0-T1 SVA (mm). METHODS Six cadaveric cervical spines (occiput-T1) were mounted with a 5 kg mass simulating head weight. Forces and moments were recorded with a load cell. Motion was recorded with optoelectric sensors placed at each level, and a thin cut CT was used to create a 3-dimensional reconstruction. The head was constrained to maintain horizontal gaze. T1 tilt and SVA were adjusted by rotating or translating the test bed (respectively) to find the condition requiring the least extrinsic force to maintain. T1 tilt was then decreased, and SVA was adjusted to minimize extrinsic force and measured. T1 tilt was then increased and SVA adjusted and measured. RESULTS T1 tilt was decreased an average of 6.49 ± 1.39° (mean ± SD) from baseline, requiring a decrease in C0-T1 SVA of 28.14 ± 17.41 mm to achieve neutral posture. T1 tilt was increased 35.12 ± 37.08° from baseline, leading to an increase in SVA of 8.80 ± 2.72 mm. CONCLUSIONS As T1 tilt was increased from baseline, an increase in C0-T1 SVA was required to maintain neutral posture. As T1 tilt was decreased, a decrease in SVA was required. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

287. T1 tilt and clavicle angle are the best predictors of postoperative shoulder balance in AIS patients: a review of 347 cases

BACKGROUND CONTEXT Shoulder imbalance after PSF is a major concern. Most studies have analyzed multiple radiographic parameters associated with postop uneven shoulders. However, there is paucity in the literature analyzing predictors for balanced shoulders. PURPOSE This study evaluated XRs of AIS patients who underwent PSF, and control patients (no spinal curvature) to identify radiographic predictors of shoulder balance. STUDY DESIGN/SETTING Ambispective review. PATIENT SAMPLE A total of 347 AIS patients that underwent PSF. OUTCOME MEASURES T1 tilt, clavicle angle, radiographic shoulder height (RSH). METHODS Radiographic shoulder height (RSH) was used as our proxy for shoulder height. RSH RESULTS Part I: 211 control patients were evaluated. Of these, 191 had normal RSH and 20 were abnormal. T1 tilt (2.0 vs 4.1) and CA (1.1 vs 4.95) were significantly different between the two groups (p CONCLUSIONS Restoring shoulder balance in AIS patients is a challenging aspect of surgery. We found that restoring the CA FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

195. Residual curve and truncal shift impact patient satisfaction after surgery for adolescent idiopathic scoliosis

BACKGROUND CONTEXT Prior adolescent idiopathic scoliosis (AIS) literature has demonstrated that patient satisfaction correlated weakly with individual SRS-22r domains and did not correlate with specific radiographic parameters. PURPOSE The purpose of this study is to demonstrate the effect of residual deformity on patient satisfaction. We hypothesize that in patients with AIS, residual deformity maybe associated with worse satisfaction. STUDY DESIGN/SETTING Retrospective analysis of a prospective AIS registry. PATIENT SAMPLE A total of 1,229 Lenke 1 and 2 AIS patients with available radiographic data and SRS scores at the 2-year follow-up were included. OUTCOME MEASURES Patient satisfaction using the SRS-22r satisfaction domain, categorized into 2 groups: Complete satisfaction (5/5) and incomplete satisfaction/dissatisfaction ( METHODS A total of 1,229 Lenke 1 and 2 AIS patients with available radiographic data and SRS scores at the 2-year follow-up were included. A score of 5 on the SRS-22r satisfaction domain at 2 years was considered “complete satisfaction,” and anything below a score of 5 was considered “incomplete satisfaction/dissatisfaction.” Radiographic parameters that were 2 standard deviations below the mean were deemed to have a “residual deformity.” Univariate and binary logistic analyses were performed to assess the association of residual deformity with patient satisfaction. RESULTS At the 2-year follow-up, 689 (60%) patients reported complete satisfaction, while 455 (40%) reported incomplete satisfaction/dissatisfaction. Radiographic factors associated with incomplete satisfaction/dissatisfaction were: residual trunk shift (OR 3.32, p=0.001) and residual major curve (OR 1.7, p=0.036). Patients with residual trunk shift and major curve also had worse SRS-22r self-image domain scores at the 2-year follow-up. Residual differences in shoulder height (p=0.534), T1 tilt angle (p=0.062), Apex to CSVL distance (p=0.969), and percent correction of the major curve (p=0.102) did not reach statistical significance for predicting incomplete satisfaction/dissatisfaction. CONCLUSIONS Residual curve (>34) and truncal shift (>2.2cm) impact patient satisfaction after surgery for AIS. These factors ought to be taken into account during surgical planning. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Clinical photography in severe idiopathic scoliosis candidate for surgery: is it a useful tool to differentiate among Lenke patterns?

Clinical photography has proven to be reliable for posture assessment in adolescents and young adults with idiopathic scoliosis. This paper attempts to elucidate whether clinical photography is capable of distinguishing the distinctive characteristics in trunk deformity of the different Lenke patterns in patients with severe scoliosis candidate for surgery. One hundred and seventy-three patients (82% women), average age of 20.8years and average largest curve magnitude of 58.7° were included. PA standing full-spine X-rays and digital photographs from the back of the trunk were measured. It is used to measure magnitude of the proximal thoracic (PTC), main thoracic (MTC) and thoracolumbar/lumbar (TL/LC) curves, T1 tilt and the clavicle-rib intersection angle. It is used to measure shoulder height angle, axilla height angle, waist height angle (WHA), right and left waist angles and trunk areas. One-way ANOVA to test mean differences among Lenke types for radiological and photographic measurements was performed. ROC curve analysis was conducted to find out cutoff values in photographic measurements to differentiate among curve patterns. Most radiological and photographic measurements differ among curve patterns. On ROC curve analysis, solid cutoff values were found for WHA (AUC = 0.8), left waist angle (AUC = 0.81), right waist angle (AUC = 0.81) and the difference between left and right waist angles (AUC = 0.86) to differentiate between types 1 and 2 and the other three types (3, 5 and 6). Clinical photography is a valid method for assessing trunk asymmetry in severe idiopathic scoliosis. Specifically, for waist area measurements, robust cutoff values can be determined to discriminate among different curve patterns according to Lenke classification. These slides can be retrieved under Electronic Supplementary Material.

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 DesignA retrospective cohort study.PurposeThis 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 LiteratureStudies have reported PSI due to excessive correction of the main thoracic curve.MethodsWe 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).ResultsThe 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.ConclusionsHooks at the UIV could adjust the shoulder balance to avoid long-term PSI in patients with AIS.