Lenke Type Research Articles

Shoulder balance in Lenke type 2 adolescent idiopathic scoliosis: Should we fuse to the second thoracic vertebra?

ObjectivesThere are many different systems recommending upper instrumented vertebra (UIV) for Lenke type 2 adolescent idiopathic scoliosis (AIS), several of which suggest that all Lenke type 2 AIS patients should be fused to the second thoracic vertebra (T2). However, all previously proposed UIV selecting systems do not accurately predict postoperative shoulder balance. We investigated whether fusing to T2 could prevent postoperative shoulder imbalance and identified circumstances under which to fuse up to T2. Patients and methodsWe retrospectively collected all patients with typical Lenke type 2 AIS who received surgery by one spine surgeon in our hospital from 2010 to 2014. Lateral shoulder balance was assessed utilizing radiographic shoulder height difference (RSH), coracoid height difference (CHD), clavicle-rib intersection difference (CRID), and clavicle angle (CA). Medial shoulder balance was assessed by T1 tilt angle and first rib angle (FRA). Lateral shoulders were considered to be level if the absolute value of RSH was less than 10 millimeters. All patients were divided into two groups as follows: 1) T2 group: UIV of T2 (n=49); and 2) below-T2 group: UIV of T3 (n=24) or T4 (n=6). Patients were assessed before surgery and at final follow-up with a minimum follow-up duration of 24 months. ResultsSeventy-nine typical Lenke type 2 AIS patients were identified. Preoperative CHD and CA were significantly associated with postoperative lateral shoulder imbalance (both p=0.045), whereas the UIV level was not significantly associated with it. Both fusing to T2 and to below T2 could improve RSH (p<0.001 and p=0.001, respectively). Fusing to T2 slightly worsened CHD, CRID, and CA at last follow-up (all p<0.001), while fusing to below T2 improved these lateral shoulder balance parameters (p=0.042, p<0.001, and p=0.007, respectively). For medial shoulder balance, fusing to below T2 worsened T1 tilt angle and FRA at last follow-up (p=0.025 and p<0.001, respectively), while fusing to T2 effectively kept these medial shoulder parameters in balance. In addition, for patients with an elevated left border of T1, the T2 group had worse preoperative T1 tilt angle but gained better postoperative T1 tilt angle than the below-T2 group (p<0.001 and p=0.040, respectively). ConclusionPreoperative lateral shoulder balance, more so than the UIV level, can strongly influence postoperative lateral shoulder balance. Fusing to T2 can only effectively improve medial shoulder balance, not lateral shoulder balance (CHD, CRID, and CA). Moreover, a positive T1 tilt angle is an indicator for fusing to T2 to improve medial shoulder balance.

Improved restoration of thoracic kyphosis using a rod construct with differentiated rigidity in the surgical treatment of adolescent idiopathic scoliosis.

OBJECTIVE The objective of this study was to compare postoperative sagittal alignment among 3 rod constructs with different rigidity profiles. METHODS This was a dual-center retrospective cohort study involving 2 consecutive cohorts in which patients were surgically treated for adolescent idiopathic scoliosis. Lenke Type 5 curves were excluded. Patients were operated on with all-pedicle screw instrumentation using 3 different rod constructs. The first group was operated on using a hybrid construct (HC) consisting of a normal circular rod on the convex side and a beam-like rod (BR) on the concave side. The second group was operated on with a standard construct (SC) using bilateral BRs in the full length of the fusion. The third group was operated on with a modified construct (MC). The modified rods have a beam-like shape in the caudal portion, but in the cranial 2 or 3 fusion levels the rod transitions to a circular shape with a smaller anteroposterior diameter. Radiographs were analyzed preoperatively and at the first postoperative follow-up (range 1-8 weeks). The primary outcome was pre- to postoperative change in thoracic kyphosis (TK), and the secondary outcome was the ability to achieve postoperative TK within the normal range. RESULTS The HC, SC, and MC groups included 23, 70, and 46 patients, respectively. The 3 groups did not differ significantly in preoperative demographic or radiographic parameters. The mean ± standard deviation of the preoperative main curve was 60.7° ± 12.6°, and the mean of curve correction was 62.9% ± 10.4% with no significant difference among groups (p ≥ 0.680). The groups did not differ significantly in coronal balance or proximal or thoracolumbar curve correction (p ≥ 0.189). Mean postoperative TK was 23.1° ± 6.3°, 19.6° ± 7.6°, and 23.4° ± 6.9° in the HC, SC and MC groups, respectively (p = 0.013), and the mean change in TK was -3.5° ± 11.3°, -7.1° ± 11.6°, and 0.1° ± 10.9°, respectively (p = 0.005). The MC group had significantly higher postoperative TK and less loss of TK compared with the SC group (p ≤ 0.018). Postoperative TK ≤ 10° was found in 12 patients (17%) in the SC group, 1 patient (5%) in the HC group, and 1 patient (2%) in the MC group (p = 0.021). There were no differences in proximal alignment, thoracolumbar alignment, or sagittal vertical axis (p ≥ 0.249). Lumbar lordosis was 58.9° ± 11.2° in the HC group versus 52.0° ± 1.3° and 55.0° ± 11.0° and the SC and MC groups, respectively (p = 0.040). CONCLUSIONS In the 3 rod constructs with different rigidity profiles, significantly better restoration of kyphosis was achieved with the use of bilateral modified rods compared with bilateral standard rods. In the MC and HC groups, the rate of severe postoperative hypokyphosis was significantly lower than in the SC group. This is the first study to describe the clinical use of a rod with a reduced proximal diameter and show marked radiographic improvement in sagittal alignment.

Cardiorespiratory Function Does Not Improve 2 Years After Posterior Surgical Correction of Adolescent Idiopathic Scoliosis.

A prospective evaluation of cardiorespiratory function following spinal fusion in adolescent idiopathic scoliosis (AIS). To evaluate the cardiopulmonary function during exercise in patients with severe AIS, before and 2 years after undergoing a posterior spinal fusion. After surgical correction of scoliosis, a greater cardiorespiratory adaptation to exercise would be expected from correction of the rib cage associated with the spine deformity. However, there is no clear evidence regarding whether tolerance to maximum exercise improves in the medium term after surgery in patients with severe curves. We include patients with AIS proposed for posterior surgical correction aging between 12 and 17 years. Every patient had a Cobb angle >45° and a Lenke type 1A scoliosis. Cardiac and respiratory functional measures, such as heart rate and blood pressure, maximum oxygen consumption (VO2max), eliminated volume of carbon dioxide (VCO2), quotient between ventilation and volume of exhaled carbon dioxide (VE/CO2), respiratory exchange rate, ventilatory capacity at maximal exercise (VEmax), were recorded before and 2 years after surgery. Twenty patients were included in our study, 15 girls and 5 boys, with an average age of 13 years. The main scoliotic curve was corrected in the coronal plane in an average of 71.9%. The maximal aerobic power expressed by body weight normalized VO2max was found preoperatively to have an average of 30.9 ± 6.2 mL/kg/minute, indicating a poor aerobic capacity, which did not improve at final follow-up, decreasing to a mean value of 29.3 ± 5.7 but without statistical significance. However, the percentages of curve correction showed a statistically significant correlation with VO2max (r = 0.534; P < 0.05). Patients with severe adolescent idiopathic scoliosis Lenke type 1A showed limited cardiorespiratory tolerance to maximum exercise that did not improve 2 years after surgery. 3.

Full fusion of proximal thoracic curve helps to prevent postoperative cervical tilt in Lenke type 2 adolescent idiopathic scoliosis patients with right-elevated shoulder

BackgroundTo date, no study had reported the phenomenon of deteriorated postoperative cervical tilt in Lenke type 2 adolescent idiopathic scoliosis patients. The purpose of this study is to evaluate the cervical tilt in Lenke type 2 adolescent idiopathic scoliosis patients with right-elevated shoulder treated by either full fusion or partial/non fusion of the proximal thoracic curve.MethodsA total of 30 Lenke type 2 AIS patients with preoperative right-elevated shoulder underwent posterior spinal instrumentation from 2009 to 2011 were included in this study. All the subjects were divided into 2 groups according to the selection of upper instrumented vertebra. There were 14 cases proximally fused to T1 or T2 (Group A) and 16 cases proximally fused to T3 or below (Group B). Both standing anteroposterior and sagittal X-ray films of the spine obtained preoperatively, one week after the operation, and at a minimum of two-year follow-up were analyzed with respect to the following parameters: cervical tilt, T1 tilt, proximal thoracic Cobb angle, main thoracic Cobb angle, apical vertebral translation of proximal thoracic curve, apical vertebral translation of main thoracic curve, radiographic shoulder height, cervical lordosis, proximal thoracic kyphosis and main thoracic kyphosis.ResultsMost (83.3%) of the patients in these two groups gained satisfactory shoulder balance after surgery. However, the cervical tilt significantly improved in group A (p < 0.001) but deteriorated in group B (p < 0.001). In group A, the decrease of cervical tilt significantly positively correlated with that of T1 tilt (p < 0.001). In group B, the increase of cervical tilt significantly positively correlated with both the increase of T1 tilt (p < 0.001) and the increase of apical vertebral translation of proximal thoracic curve (p < 0.05).ConclusionsLenke type 2 AIS patients with right-elevated shoulder gain improved shoulder but deteriorated cervical tilt after partial/non fusion of proximal thoracic curve. Full fusion of proximal thoracic curve helps to prevent the residual cervical tilt in these patients.

Is vertebral rotation correction maintained after thoracoscopic anterior scoliosis surgery? A low-dose computed tomography study

BackgroundAxial vertebral rotation is a key characteristic of adolescent idiopathic scoliosis (AIS), and its reduction is one of the goals of corrective surgery. Recurrence of deformity after surgical correction may relate to rotation changes that occur in the anterior vertebral column after surgery, but whether any change occurs within the fused segment or in adjacent unfused levels following thoracoscopic anterior spinal fusion (TASF) is unknown. An analysis of measurements from an existing postoperative CT dataset was performed to investigate the occurrence of inter- and intra-vertebral rotation changes after TASF within and adjacent to the fused spinal segment and look for any relationships with the Cobb angle and rib hump in the two years after surgery.Methods39 Lenke Type 1 main thoracic patients underwent TASF for progressive AIS and low dose computed tomography scanning of the instrumented levels of the spine at 6 and 24 months after surgery. Vertebral rotation was measured at the superior and inferior endplates on true axial images for all vertebral levels in the fused segment plus one adjacent level cranially and caudally. Intra-observer variability for rotation measurements was assessed using 95% limits of agreement to detect significant changes in inter/intra-vertebral rotation.ResultsSignificant local changes in inter- and intra-vertebral rotation were found to have occurred between 6 and 24 months after anterior surgical fusion within the fused spinal segment, albeit with no consistent pattern of location or direction within the instrumented fusion construct. No significant en-bloc movement of the entire fused spinal segment relative to the adjacent un-instrumented cranial and caudal intervertebral levels was found. No clear correlation was found between any vertebral rotation changes and Cobb angle or rib hump measures.ConclusionsLocalised inter- and intra-vertebral rotation occurs between 6 and 24 months after TASF, both within the instrumented spinal segments and in the adjacent un-instrumented levels of the adolescent spine. The lack of measurable en-bloc movement of the fused segment relative to the adjacent un-instrumented levels suggests that overall stability of the instrumented construct is achieved, however the vertebrae within the fusion mass continue to adapt and remodel, resulting in ongoing local anatomical and biomechanical changes in the adolescent spine.

Key Vertebral Pedicle Screw Strategy for the Correction of Flexible Lenke Type 1 Adolescent Idiopathic Scoliosis

A retrospective clinical and radiographic study. The aim of this study was to evaluate outcomes of the key vertebral pedicle screw strategy (KVPSS) for the correction of flexible Lenke type 1 adolescent idiopathic scoliosis (AIS) with a minimum follow-up of 5 years. The KVPSS has been described as an alternative screw placement strategy for surgically treating the main thoracic curve in AIS patients. However, there have been no long-term, three-dimensional correction studies of selective thoracic fusion using the KVPSS in Lenke type 1AIS. Twenty consecutive patients with Lenke type 1 main thoracic AIS underwent one-stage posterior correction and fusion using the KVPSS. Preoperative and postoperative radiographic and clinical parameters were analyzed. The mean preoperative major thoracic curve was 47.4° ± 5.8°, and mean corrections of 67.0%, 63.4%, and 61.5% were observed at the immediate, 2-year postoperative, and final follow-ups, respectively. Thoracickyphosis decreased significantly from the preoperative period to the immediate postoperative period (P = 0.042) but did not change significantly from the 2-year postoperative follow-up to the final follow-up (P = 0.067). Apical vertebral rotation achieved 34.7% correction and exhibited correction loss of 8.2% at the final follow-up. The average intraoperative blood loss was 802.3 mL, and the mean operative time was 138.6 minutes. SRS-22 scores for self-image and satisfaction improved significantly from the preoperative period to the final follow-up. No neurologic or implant-associated complications were observed in this study. The KVPSS is an effective method for correcting Lenke type 1 AIS and achieves satisfactory correction of the deformity. Relative to other approaches, the KVPSS can not only achieve a satisfactory and cost-effective clinical outcome but also reduce both operative time and intraoperative blood loss. 4.

What is the Difference in Morphologic Features of the Thoracic Pedicle Between Patients With Adolescent Idiopathic Scoliosis and Healthy Subjects? A CT-based Case-control Study

Describing the morphologic features of the thoracic pedicle in patients with adolescent idiopathic scoliosis is necessary for placement of pedicle screws. Previous studies showed inadequate reliability owing to small sample size and heterogeneity of the patients surveyed. To use CT scans (1) to describe the morphologic features of 2718 thoracic pedicles from 60 female patients with Lenke Type 1 adolescent idiopathic scoliosis and 60 age-, sex-, and height-matched controls; and (2) to classify the pedicles in three types based on pedicle width and analyze the distribution of each type. A total of 2718 pedicles from 60 female patients with Lenke Type 1 adolescent idiopathic scoliosis and 60 matched female controls were analyzed via CT. All patients surveyed were diagnosed with adolescent idiopathic scoliosis, Lenke Type 1, at the First Affiliated Hospital of Sun Yat-sen University, and all underwent pedicle screw fixation between January 2008 and December 2013 with preoperative radiographs and CT images on file. We routinely obtained CT scans before these procedures; all patients who underwent surgery during that period had CT scans, and all were available for analysis here. Control subjects had CT scans for other clinical indications and had no abnormal findings of the spine. The control subjects were chosen to match patients in terms of age (15 ± 2.6 years versus 15 ± 2.6 years) and sex. Height of the two groups also was matched (154 ± 9 cm versus 155 ± 10 cm; mean difference, -1.06 cm; 95% CI, -1.24 to -0.81 cm; p < 0.001). Pedicle width and length were measured from T1 to T12. The thoracic spine was classified in four regions: apical vertebra in the structural curve (AV-SC), nonapical vertebra in the structural curve (NAV-SC), apical vertebra in the nonstructural curve (AV-NSC), and nonapical vertebra in the nonstructural curve (NAV-NSC). Pedicles were classified in three types: pedicle width less than 2 mm as Type I, 2 mm to 4 mm as Type II, and greater than 4 mm as Type III. Types I and II were defined as dysplastic pedicles. Paired t test, independent samples t test, one-way ANOVA, followed by Bonferroni's post hoc test and chi-square or Fisher's exact tests were used for statistical comparisons between patients and controls, as appropriate. No difference was found between pedicle width on the convex side (PWv) and in controls (PWn), but pedicle width on the concave side (PWc) (4.99 ± 1.87 mm) was found to be narrower than PWv (6 ± 1.66 mm) and PWn (6 ± 1.45 mm). The variation degree of pedicle width (VDPW) was greatest in the AV-SC region (34% ± 37%), in comparison to AV-NSC (20% ± 25%) (mean difference, 14%; 95% CI, 1.15%-27%; p = 0.025), NAV-SC (17% ± 30%) (mean difference, 17%; 95% CI, 7%-27%; p < 0.001), and NAV-NSC (11% ± 24%) (mean difference, 24%; 95% CI, 13%-34%; p < 0.001). Dysplastic pedicles appeared more in patients with adolescent idiopathic scoliosis (22%; 293 of 1322) compared with controls (13%; 178 of 1396) (odds ratio [OR] = 0.51; 95% CI, 0.42-0.63; p < 0.001). In patients with adolescent idiopathic scoliosis, they commonly occurred on the concave side 34% (228 of 661) and on the AV-SC region (32%; 43 of 136). Pedicle width on the concave side was narrower than pedicle width on the convex side and pedicle width in healthy control subjects. The apical vertebra in the structural curve was the most variegated region of the curve with the highest prevalence of dysplastic pedicles. Our study can help surgeons perform preoperative assessments in females with adolescent idiopathic scoliosis, and with preoperative and intraoperative management for difficult pedicle screw placement. In particular, our results suggest that surgeons should exercise increased vigilance when selecting pedicle screw dimensions, especially in the concave aspect of the mid-thoracic curve, to avoid cortical breeches. Future studies should evaluate other Lenke types of adolescent idiopathic scoliosis, and males with adolescent idiopathic scoliosis.

Predictors of shoulder level after spinal fusion in adolescent idiopathic scoliosis.

For patients with adolescent idiopathic scoliosis, shoulder balance influences their treatment satisfaction and psychological well-being. Several parameters are known to affect postoperative shoulder balance, but few prognostic models are as yet available. This study aimed to identify independent predictive factors that can be used to assess preoperatively which patients are at risk of postoperative shoulder elevation, and to build a linear prediction model. N=102 patients with all Lenke types were reviewed radiographically before surgery and 1year afterward. The outcome measures were coracoid height difference (CHD), clavicular angle (CA), and clavicle-first rib intersection difference (CiRID). Predictive factors commonly used in the literature were investigated using correlation analysis and statistical testing. Significant contributing factors were included in three multiple linear regression models (for CHD, CA, and CiRID). The mean shoulder level (CHD) significantly changed from a lower left shoulder value of -8.5mm before surgery to 3.3mm at the follow-up examination. A high preoperative left shoulder level by CiRID, a large amount of Cobb angle correction of the distal thoracic curve, a low preoperative Cobb angle in the lumbar curve, and a structural proximal thoracic curve proved to be determinants and thus risk factors for left-sided shoulder elevation after surgery. The three models predicting CHD, CA, and CiRID at the follow-up examination included these four risk factors and were significant. Preoperative variables have the strongest influence on shoulder level after spinal instrumentation. Additionally, extensive correction of the distal thoracic curve can cause elevation of the left shoulder.

INTRAOPERATIVE TRACTION IN SURGERY FOR ADOLESCENT IDIOPATHIC SCOLIOSIS

Objective. To analyze the effectiveness of intraoperative traction in the treatment of adolescent idiopathic scoliosis, including in relation to the initial magnitude of scoliotic curve. Material and Methods . Data on patients meeting the following criteria were selected from the electronic database and analyzed: idiopathic scoliosis (Lenke types I, III, V); age 10 to 20 years; surgery performed through posterior approach; hook or hybrid (using of pedicle screws only in the lumbar spine, at 2-4 levels) fixation; no previous history of spine surgery; and follow-up period at least two years. Results . Flattening of thoracic kyphosis and alignment of lumbar lordosis during surgical correction were significantly more pronounced in the traction group. Postoperative changes in the sagittal contour of the thoracic and lumbar spine did not differ significantly between the traction and no-traction groups. Intraoperative traction was associated with significantly reduced blood loss, though operation time decreased statistically insignificantly. Normalization of the frontal imbalance in the immediate and long-term postoperative periods was different in the two groups, but these differences were insignificant. Intraoperative traction was most effective in the group with deformities of 50° to 75°, although it also increased the achieved correction in patients with scoliosis of a smaller and greater magnitude. Conclusion . The operation performed with intraoperative traction allows achieving greater correction during an intervention and smaller loss of correction during a long follow-up period than that without a distraction influence. This applies equally to both primary and secondary curvatures.

The mechanisms underlying the variety of preoperative directionalities of shoulder tilting in adolescent idiopathic scoliosis patients with double thoracic curve.

Preoperative directionality of shoulder tilting seems to be independent of the radiographic features of proximal thoracic (PT) curve in adolescent idiopathic scoliosis (AIS) patients. To date, no study had investigated the mechanisms underlying the variety of preoperative directionalities of shoulder tilting in AIS patients. The purpose of this study was to evaluate the differences of radiographic features between Lenke type 2 (double thoracic curve) AIS patients with different preoperative directionalities of shoulder tilting. A total of 130 Lenke type 2 AIS patients were included in this study and were divided into two groups according to the value of radiographic shoulder height (RSH). There were 78 cases (71 females and 7 males) with RSH less than 0cm in Group A and 52 cases (44 females and 8 males) with RSH equal to or more than 0cm in Group B. Preoperative standing anteroposterior X-ray films of the spine were obtained in all these subjects and were analyzed with respect to the following parameters: T1 tilt, PT Cobb angle, main thoracic (MT) Cobb angle, the apical level of PT curve, the apical level of MT curve, and RSH. These parameters were compared between these two groups and the correlations between RSH and the other parameters were analyzed in all of these subjects. No significant difference was found between these two groups with respect to PT Cobb angle or the apical level of PT curve (P>0.05). The apical level of MT curve was significantly more proximal in Group A compared with Group B (P<0.05). The MT Cobb angle was significantly larger in Group A compared with Group B (P<0.05). Both the T1 tilt and the PT Cobb angle/MT Cobb angle ratio in Group A were significantly smaller than those in Group B (P<0.05). The RSH was positively associated with T1 tilt, the apical level of MT curve, and the PT Cobb angle/MT Cobb angle ratio, but was negatively associated with MT Cobb angle (P<0.05). The directionality of shoulder tilting is diverse in Lenke type 2 AIS patients. The preoperative directionality of shoulder mainly depends on the profile of MT curve rather thanthat of PT curve. The RSH should be carefully evaluated before making a surgical plan in these patients.

Cervical kyphosis in patients with Lenke type 1 adolescent idiopathic scoliosis: the prediction of thoracic inlet angle

BackgroundSeveral studies have explored cervical kyphosis (CK) in adolescent idiopathic scoliosis (AIS) patients. However, few studies have evaluated the cervical alignment in these patients according to their coronal curve type. The aim of this study was to analyze the radiological features of cervical sagittal alignment in Lenke 1 AIS patients before and after surgery.MethodsThis is a retrospective study enrolled 50 patients. Preoperative and postoperative standing full-length radiographs (at last follow-up after operation) were used to measure the coronal and sagittal parameters. Main sagittal parameters included C2–C7 angle, thoracic inlet angle (TIA), T1 slope, proximal thoracic kyphosis (PTK, T1-5 kyphosis) and thoracic kyphosis (TK, T5-12 kyphosis).ResultsThe TIA of patients with CK was significantly smaller than that of patients with CL (63.0° vs. 76.3°, p < 0.05) and the cutoff value was 71°. The TIA of patients with CK after surgery was significantly smaller than that of patients with CL postoperatively (62.5° vs. 74.6°, p < 0.05) and the cutoff value was 62°. In patients with postoperative CL, there was a significant increase in their PTK and a reduction in their TK, regardless of preoperative CL or CK. In patients whose CL deteriorated to CK after surgery, both their PTK and TK significantly decreased after surgery.ConclusionsPatients with TIA less than 71° were more likely to have CK. And patients with TIA less than 62° would lead to the postoperative uncorrected or new onset of CK. The increased PTK after operation could have a beneficial effect on the improvement of CL.

Determinants of the biomechanical and radiological outcome of surgical correction of adolescent idiopathic scoliosis surgery: the role of rod properties and patient characteristics.

Aim of the study was to evaluate the role of the mechanical properties of the rod and of the characteristics of the patients (age, skeletal maturity, BMI, and Lenke type) in determining the deformity correction, its maintenance over time and the risk of mechanical failure of the instrumentation. From March 2011 to December 2014 120 patients affected by AIS underwent posterior instrumented fusion. Two 5.5-mm CoCr rods were implanted in all patients. For every patient, age, sex, Risser grade, Lenke type curve, flexibility of the main curve, body mass index (BMI), and percentage of correction were recorded. In all patients, the Cobb angle value and rod curvature angle (RC) were evaluated. RC changes were registered and correlated to each factor to establish a possible statistically significance in a multivariate analysis. A biomechanical model was constructed to study the influence of rod diameter and material as well as the density of the anchoring implants in determining stress and deformation of rods after contouring and implantation. Radiographic and biomechanical analysis showed a different mean rod deformation for concave and convex side: 7.8° and 3.9°, respectively. RC mean value at immediate follow-up was 21.8° for the concave side and 14.6° for the convex. At 2-year minimum follow-up, RC value increases 1.5° only for the concave side. At 3.5-year mean follow-up, RC value increases 2.7°, p=0.003, for the concave side and 1.3° for the convex, p=0.06. The use of the stiffest material as well as of the lowest diameter resulted in higher stresses in the rods. The use of either a low or a high instrumentation density resulted only in minor differences in the loss of correction. Rod diameter and material as well as patient characteristics such as BMI, age, and Risser grade play an important role in deformity correction and its maintenance over time.

Adolescent Scoliosis 1A001: Radiographic Results of Selecting the Touched Vertebra as the Lowest Instrumented Vertebra in Lenke Type 1 (Main Thoracic) & Type 2 (Double Thoracic) Curves at a Minimum 5-year Follow-up

Introduction:A prior study showed the touched vertebra (TV), defined as the most cephalad thoracolumbar/lumbar vertebra “touched” by the center sacral vertical line (CSVL), as a potential landmark vertebra & recommended lowest instrumented vertebra (LIV) as well. We evaluated a large cohort of Lenke type 1 & 2 cases to determine if selecting the TV as the LIV will produce optimal positioning at a min. 5 yrs postoperative. Our hypothesis was that it would and that fusing short of the TV would lead to a suboptimal result.Material and Methods:299 pts with Lenke 1 (n = 207) or Lenke 2 (n = 92) AIS curves at a min. 5 yr f/u were evaluated. The TV was selected on the preoperative x-ray by 2 independent examiners & confirmed for agreement. The LIV selected was compared to the preoperative TV as well as the LIV-CSVL distance at min. 5 yr f/u. Comparison was made on the LIV-CSVL distance in pts fused short of the TV, to the TV or distal to the TV using standard statistical software.Results:When comparing the entire cohort, differences in 5 yr LIV-CSVL absolute values between the 3 groups approached, but did not reach, significance ( = .055). In a subanalysis of the lumbar A modifiers (n = 161), main effect ANOVA indicated a significant difference among the 3 groups ( = .002). Post hoc comparison revealed that pts fused short of the TV (TV-1) had significantly greater LIV-CSVL distance values than those fused to the TV ( = .006) & those fused distal to the TV (TV+1, = .002). There was no significant difference among the 3 groups when looking at lumbar B (n = 76, p = 0.424) & lumbar C (n = 62, = .326) modifiers.Conclusion:Selecting the touched vertebra (TV) as the LIV for Lenke type 1A & 2A curves produced optimal LIV positioning at a minimum 5 yrs postoperative, while fusing short of the TV showed statistically increased LIV- CSVL translation. Understanding & utilizing the TV rule assists the surgeon in proper LIV selection in Lenke type 1A & 2A curve patterns for AIS.

Adolescent Scoliosis 1A001: Radiographic Results of Selecting the Touched Vertebra as the Lowest Instrumented Vertebra in Lenke Type 1 (Main Thoracic) & Type 2 (Double Thoracic) Curves at a Minimum 5-year Follow-up

Introduction:A prior study showed the touched vertebra (TV), defined as the most cephalad thoracolumbar/lumbar vertebra “touched” by the center sacral vertical line (CSVL), as a potential landmark vertebra & recommended lowest instrumented vertebra (LIV) as well. We evaluated a large cohort of Lenke type 1 & 2 cases to determine if selecting the TV as the LIV will produce optimal positioning at a min. 5 yrs postoperative. Our hypothesis was that it would and that fusing short of the TV would lead to a suboptimal result.Material and Methods:299 pts with Lenke 1 (n = 207) or Lenke 2 (n = 92) AIS curves at a min. 5 yr f/u were evaluated. The TV was selected on the preoperative x-ray by 2 independent examiners & confirmed for agreement. The LIV selected was compared to the preoperative TV as well as the LIV-CSVL distance at min. 5 yr f/u. Comparison was made on the LIV-CSVL distance in pts fused short of the TV, to the TV or distal to the TV using standard statistical software.Results:When comparing the entire cohort, differences in 5 yr LIV-CSVL absolute values between the 3 groups approached, but did not reach, significance (P = .055). In a subanalysis of the lumbar A modifiers (n = 161), main effect ANOVA indicated a significant difference among the 3 groups (P = .002). Post hoc comparison revealed that pts fused short of the TV (TV-1) had significantly greater LIV-CSVL distance values than those fused to the TV (P = .006) & those fused distal to the TV (TV+1, P = .002). There was no significant difference among the 3 groups when looking at lumbar B (n = 76, p = 0.424) & lumbar C (n = 62, P = .326) modifiers.Conclusion:Selecting the touched vertebra (TV) as the LIV for Lenke type 1A & 2A curves produced optimal LIV positioning at a minimum 5 yrs postoperative, while fusing short of the TV showed statistically increased LIV- CSVL translation. Understanding & utilizing the TV rule assists the surgeon in proper LIV selection in Lenke type 1A & 2A curve patterns for AIS.

Both Bilateral Breast Volume Discrepancy and Asymmetric Anterior Chest Wall Shape Contribute to the Unsightly Breast Contour in Female Right Thoracic Idiopathic Scoliosis.

A retrospective radiographic study. To evaluate the asymmetry of breast volume (BV) and shape in female adolescent idiopathic scoliosis (AIS) patients and to define their relationship with deformed components of the anterior chest wall and curved spine. The higher incidence of asymmetric breast development in AIS was described by prior studies. However, the interplay between scoliosis curve magnitude and severity of breast asymmetry (BA) are unknown. A total of 73 surgically treated female right thoracic AIS patients classified as Lenke type I were enrolled in this study, with the average Cobb angle being 52.08±11.68 degrees. The Image J software was utilized to calculate BV. Both concave and convex radiographic parameters of breast shape were measured including the extraversion angle (EA), the coverage angle (CA), the axial breast height, the vertical breast height (VBH), and the nipple-to-sternum distance. The inclination angles of the concave and convex anterior chest wall were also assessed. BA was calculated according to the formula as follows: BA=(concave-convex)×BV/[(concave+convex)×BV]/2. The measurements of spinal deformity parameters included the Cobb angle, the RAsag angle, and the RAml angle. Paired t test was performed to analyze the asymmetry of breast shape, and Pearson correlation analysis was utilized to define the correlation between the breast shape, spinal deformity, and the inclination of anterior chest wall. The concave BV, EA, axial breast height, and vertical breast height were significantly larger than those of the convex side (P<0.05), whereas the concave CA and the inclination angle of the anterior chest wall were significantly smaller than those of the convex side (P<0.05). No difference was detected between the concave and the convex nipple-to-sternum distance (P>0.05). The averaged BA was 11.4%, with the ratio of asymmetry beyond 10% being 52.1%. No statistically significant relationships between BA and Cobb angle, RAsag angle, RAml angle were detected (P>0.05). The inclination angle of the anterior chest wall demonstrated significant correlation with EA (P<0.001) and CA (P<0.001), respectively. The incidence of BA in AIS is notable, with the concave breast being larger, more extroversive, and more concentrated than the convex breast. The discrepancy between concave and convex anterior chest wall inclination bound to scoliosis could have a major influence on breast orientation and profile, suggesting a synergistic role of anterior chest wall deformity and bilateral BV discrepancy in the formation of BA.

Geometric Torsion in Adolescent Idiopathic Scoliosis: A New Method to Differentiate Between Lenke 1 Subtypes.

Consecutive case series. To study geometric torsion in thoracic adolescent idiopathic scoliosis (AIS) to propose it as a numerical three-dimensional (3D) parameter that quantifies the scoliosis deformity. AIS is a 3D deformity of the spine. The most widely accepted and used classification systems, however, still rely on two-dimensional aspects of x-rays. Yet, a 3D classification of AIS remains elusive because there is no widely accepted 3D parameter in the clinical practice. Analysis of 141 patients with Lenke type-1 deformity recruited in our institution. The Lenke classification was identified by two observers and 3D reconstructions were obtained using biplanar radiographs. Geometric torsion measuring the twisting effect of the spine was computed using a novel technique by approximating local arc lengths at the neutral vertebra in the thoracolumbar segment. An inter- and intragroup statistical analysis was performed to evaluate the torsion index, and how it relates to other 3D indices. A statistically significant increase in torsion was observed between Lenke 1A (1.15 mm) and Lenke 1C (2.10 mm) subgroups. No differences were found between the Lenke 1B (1.75 mm) subgroup with either of the other two subgroups. An automatic classification based on torsion indices identified two groups: one with high torsion values (3.02 mm) and one with low torsion values (0.82 mm). Statistically significant differences were found between the main thoracic planes of maximum curvature (PMC) orientation of the high-torsion group (73.72°) and the low-torsion group (79.85°). Statistically significant differences were also found for the thoracolumbar/lumbar PMC orientation between the high-torsion group (56.41°) and the low-torsion group (49.25°). These results suggest that a numerical method of describing scoliosis in 3D is within reach. They also suggest the existence of two subgroups of 3D deformations based on torsion values (high and low) with links to PMC orientation. 4.

Cervical Sagittal Alignment Limited Adjustment After Selective Posterior Thoracolumbar/Lumbar Curve Correction in Patients With Lenke Type 5C Adolescent Idiopathic Scoliosis.

A retrospective clinical and radiographic study. The aim of this study was to analyze the radiographic change in cervical sagittal alignment (CSA) and identify the possible factors influencing the postoperative CSA in selective posterior thoracolumbar/lumbar (TL/L) curve correction. The correlation between the CSA and thoracic sagittal alignment (TSA) is a well-recognized phenomenon in patients with thoracic idiopathic scoliosis. However, little has been published about the influence of TL/L curve instrumentation on CSA. Thirty patients with Lenke type 5C adolescent idiopathic scoliosis (AIS) received the selective posterior TL/L curves fusion by pedicle screws. Preoperative and postoperative radiographic and clinical parameters were analyzed. C2-C7 lordosis less than 0 was considered a lordotic cervical spine (LCS), whereas more than 0 was considered a kyphotic cervical spine (KCS). Preoperatively, 43% of patients showed a KCS, whereas the remaining 57% showed a LCS. C2-C7 lordosis was correlated with T1-slope, thoracic kyphosis (TK), and global-TK (Gl-TK) (P < 0.05). The patients in the KCS group showed a smaller T1-slope, TK, and Gl-TK than those in the LCS group. Logistic regression analysis revealed that the T1-slope [odds ratio (OR) = 0.86, P = 0.008] and Gl-TK (OR = 0.90, P = 0.019) were risk factors for developing KCS. In the LCS group, 5 of 12 patients with LCS exhibited KCS after surgery. The T1-slope and Gl-TK in the changed group were considerably smaller than those in the maintained group (P = 0.004 and 0.035, respectively). In the KCS group, 6 of 13 patients with KCS unrecovered to LCS after the operation. The T1-slope in the unrecovered group was smaller than that in the recovered group (P = 0.045). C2-C7 lordosis was strongly correlated with the T1-slope. C2-C7 lordosis of Lenke 5C AIS was related to the global TSA rather than TK and proximal TK. As time progresses, spontaneous adjustment of CSA is limited because of the inherent rigidity of the cervical spine. 4.

Risk Factors of Proximal Junctional Kyphosis in Adolescent Idiopathic Scoliosis—The Pelvis and Other Considerations

Study DesignProspective multicenter database study. ObjectivesTo assess the incidence of proximal junctional kyphosis (PJK) in operative adolescent idiopathic scoliosis (AIS) using contemporary surgical techniques and to identify risk factors for PJK. Summary of Background DataThe incidence of PJK has been reported as high as 46% in AIS. Factors associated with PJK have been incompletely explored. MethodsProspectively enrolled 851 AIS patients (2000–2011, 78.5% female, average 14.4 years) were evaluated 2 years postoperatively. Radiographic and sagittal spinopelvic parameters and rod contour angle (RCA), a new measure that reflects the proximal contouring of the rod, were independently evaluated for association with PJK based on Lenke type. Multivariate logistic regression with backward elimination was performed to identify risk factors for PJK. ResultsOverall PJK incidence was 7.05% and varies based on Lenke type (Lenke 1, 6.35%; Lenke 2 and 4, 4.39%; Lenke 3 and 6, 11.64%; and Lenke 5, 8.49%; p = .06). Among patients with Lenke 1 curves, risk factors for PJK were loss of kyphosis after surgery, and stopping caudal to the upper end vertebra (UEV). The risk of developing PJK increases by 7.1% with each lost degree of kyphosis compared with preoperation that occurs after the instrumentation is placed. For Lenke 2 and 4 curves, loss of kyphosis and more lordotic (negative) RCA were risk factors for PJK. For Lenke 3 and 6 curves, larger preoperative T5–T12 kyphosis was the only significant risk factor for PJK. Upper instrumented vertebra (UIV) at or cephalad to the UEV was associated with increased risk of PJK in Lenke 5 curves, which was contrary to the finding for Lenke 1 curves. No significant correlation was found between sagittal pelvic parameters and developing PJK. ConclusionThe incidence of PJK in patients after surgery for AIS is 7.05% and varies based on Lenke type. Loss of kyphosis, larger preoperative kyphosis, UIV caudal to the proximal UEV (Lenke 1), UIV at or cephalad to the UEV (Lenke 5), and decreased RCA were the major risk factors for PJK in AIS. Level of EvidenceLevel II.

Sequential Magnetic Resonance Imaging Reveals Individual Level Deformities of Vertebrae and Discs in the Growing Scoliotic Spine

Study DesignThe aim of this study was to measure contributions of individual vertebra and disc wedging to coronal Cobb angle in the growing scoliotic spine using sequential magnetic resonance imaging (MRI). Clinically, the Cobb angle measures the overall curve in the coronal plane but does not measure individual vertebra and disc wedging. It was hypothesized that patients whose deformity progresses will have different patterns of coronal wedging in vertebrae and discs to those of patients whose deformities remain stable. MethodsA group of adolescent idiopathic scoliosis (AIS) patients each received two to four MRI scans (spaced 3–12 months apart). The coronal plane wedge angles of each vertebra and disc in the major curve were measured for each scan, and the proportions and patterns of wedging in vertebrae and discs were analyzed for subgroups of patients whose spinal deformity did and did not progress during the study period. ResultsSixteen patients were included in the study; the mean patient age was 12.9 years (standard deviation 1.7 years). All patients were classified as right-sided major thoracic Lenke Type 1 curves (9 type 1A, 4 type 1B, and 3 type 1C). Cobb angle progression of ≥5° between scans was seen in 56% of patients. Although there were measurable changes in the wedging of individual vertebrae and discs in all patients, there was no consistent pattern of deformity progression between patients who progressed and those who did not. The patterns of progression found in this study did not support the hypothesis of wedging commencing in the discs and then transferring to the vertebrae. ConclusionSequential MRI data showed complex patterns of deformity progression. Changes to the wedging of individual vertebrae and discs may occur in patients who have no increase in Cobb angle; therefore, the Cobb method alone may be insufficient to capture the complex mechanisms of deformity progression.

Research on in vivo kinematics characteristics of the spine in adolescent idiopathic scoliosis patients based on 3D image volume fusion technique

Objective To characterize the spinal motion of 6 degrees of freedom (6DOF) under the fulcrum bending in Lenke type 1 adolescent idiopathic scoliosis (AIS) patients using 3D image volume fusion technique. Methods Ten volunteers with Lenke type 1 AIS were examined by the Gemstone Spectral Imaging to obtain their T1-S1 vertebral morphological data in the supine position and fulcrum bending position. With the computer software, images of 2 different positions were fused with the 3D image to obtain in vivo kinematics data of each vertebral body in the target area. Results In the apical vertebrae (AV) region, the main range of motion in the fulcrum bending position ranged from -2.57°±0.95° to -1.37°±0.65°, showing significant differences between segments (P 0.05); along the vertical axis, coupling rotation ranged from 0.18°±0.47° to 1.35°±0.52°; along the coronal axis, coupling flexion and extension ranged from 1.62°± 0.41° to 2.07°± 0.37°. In the lower end vertebrae (LEV) region, the main movement ranged from -0.79°±0.63° to 0.73°±1.09°, showing significant differences between the 3 segments (P< 0.05); along the vertical axis, the coupling rotation ranged from -1.62°±1.05° to -0.60°±0.60°; along the coronal axis, the coupling flexion extension ranged from -1.41°±0.87° to -0.75°±0.66°. Conclusions In the fulcrum bending position, Lenke type 1 AIS shows a unique motion and coupling mechanism in the spine. The coupling rotational movement in the UEV region is at the same side as the lateral flexion movement. The coupling rotational motion in the AV and LEV regions is opposite the lateral flexion movement. Key words: Scoliosis; Imaging, three-dimensional; Range of motion, articular; Adolescent