Plumb Line Research Articles

Relationship between hip joint proximity area and sagittal balance parameters: an upright computed tomography study

PurposeA close relationship between sagittal spinal alignment and hip osteoarthritis (OA) has been documented. This study aimed to examine the relationship between hip joint proximity area and sagittal balance parameters in healthy subjects.MethodsThis prospective study enrolled 47 healthy volunteers who underwent 320-detector row upright computed tomography. Acquired data were reconstructed in a virtual three-dimensional space. The proximity area was determined by < 1 mm of the Hausdorff distance between the acetabulum and the femoral head. Volunteers were divided into the anterior and posterior proximity groups depending on the position of the closest area. Sagittal balance parameters [sagittal vertical axis (SVA), T1 spinopelvic inclination (T1-SPi), T1-pelvic angle, pelvic tilt, sacral slope, pelvic incidence, lumbar lordosis, thoracic kyphosis), offset distance between the centre of the acoustic meati (CAM) and C7 plumb line (CAM-C7-offset), and offset distance between the CAM and hip axis (HA) (CAM-HA-offset)] were compared between the two groups using independent sample t test.ResultsThe anterior proximity group (n = 24) had higher SVA (p = 0.016) and T1-Spi (p = 0.015) than the posterior proximity group (n = 23). CAM-HA-offset was higher in the posterior than in the anterior proximity group (p < 0.000). There was no difference in other parameters (p > 0.05).ConclusionThe anterior proximity group had a positive anterior spinal balance; the posterior proximity group may have a more posterior gravity line than the hip joint centre. The anterior spinal balance may contribute to the anterior loading of the hip joint, with known relation with the initiation and onset of hip OA.

Identification of Tibial Malrotation After Nailing Using Unique CT Scan Reference Line, and Influence of Position of Leg for Distal Locking on Rotation.

Tibial torsion can be measured by various clinical and radiological methods. Computed tomography (CT) scan measurement is currently the investigation of choice. The purpose of our study was to compare the clinical and CT scan methods to reveal malrotation after nailing of tibia and also to find out if leg position for distal locking has any influence on incidence of malrotation. We have included 106 patients (21-68years) of tibia nailing, and categorised them as category A (figure of four position n = 54) and category B (knee straight position n = 52) based on limb position for distal locking. The plumb line measurement, Thigh Foot Axis (TFA) and CT scan measurement (using new reference line) were documented and compared with the uninjured limb. We observed plumb line measurement to be the most inaccurate method followed by TFA method. CT scan measurement was the most accurate method showing external rotations (> 10º) in 32 cases (30.1%) and internal rotation (> -10º) in five cases (4.71%). The TFA method had a sensitivity of 44% and specificity of 86% in identifying malrotations. The interobserver reliability for CT scan measurement was 0.96. Even though statistically not significant (P value), figure of four position for distal locking leads to larger number of malrotations (both external and internal rotation). CT scan is the most accurate method of measuring malrotation. The new reference line used in our study provides accurate measurement of malrotation. The two different positions of leg for distal locking do not have a statistically significant influence on incidence of malrotation.

Directionality of Lumbosacral Fractional Curve Relative to C7 Plumb Line, A Novel Index Associated with Postoperative Coronal Imbalance in Patients with Degenerative Lumbar Scoliosis.

Retrospective case-control radiographic study. The aim of this study was to explore whether directionality of lumbosacral fractional curve relative to C7 plumb line (PL) affected postoperative coronal imbalance in patients with degenerative lumbar scoliosis (DLS). The spatial relationship between lumbar main curve and C7 PL was reported to have impact on postoperative coronal imbalance in DLS. Although fractional curve played more important role than lumbar main curve in DLS, the spatial relationship between fractional curve and C7 PL and their impact on the postoperative coronal balance are still unknown. One hundred one DLS patients treated with posterior instrumented fusion were reviewed. Coronal measurements included C7 migration, fractional curve, L4/L5 coronal tilt, major Cobb angle. Based on directionality of fractional curve (orientation of L4 coronal tilt was used to represent it) relative to C7 PL preoperatively, coronal patterns was separated into: consistency pattern, L4 coronally tilts toward C7 PL; opposition pattern, L4 coronally tilts opposite C7 PL; the distributions of these two patterns and Type A, B,C were analyzed. According to postoperative C7 migration, patients were divided into imbalanced group and balanced group. Compared to balanced group, the imbalanced group had higher percentage of preoperative consistency pattern (80.6% vs. 33.8%, P < 0.001) and Type C (36.1% vs. 7.7%, P < 0.001); larger fractional curve or L4 coronal tilt pre- and postoperatively, larger L5 coronal tilt postoperatively. Logistic regression analysis showed predictors for postoperative coronal imbalance were consistency pattern (odds ratio [OR] 5.103, 95% confidence interval [CI]: 1.660-15.687, P = 0.004) and type C (OR 4.061; 95% CI: 1.056-15.618; P = 0.041). Directionality of fractional curve relative to C7 PL was associated with postoperative coronal imbalance in DLS patients. In addition to type C, consistency pattern might be an independent risk factor for postoperative coronal imbalance.Level of Evidence: 3.

Mid-term results of a modified self-growing rod technique for the treatment of early-onset scoliosis.

To report the mid-term results of a modified self-growing rod (SGR) technique for the treatment of idiopathic and neuromuscular early-onset scoliosis (EOS). We carried out a retrospective analysis of 16 consecutive patients with EOS treated with an SGR construct at a single hospital between September 2008 and December 2014. General demographics and deformity variables (i.e. major Cobb angle, T1 to T12 length, T1 to S1 length, pelvic obliquity, shoulder obliquity, and C7 plumb line) were recorded preoperatively, and postoperatively at yearly follow-up. Complications and revision procedures were also recorded. Only patients with a minimum follow-up of five years after surgery were included. A total of 16 patients were included. Six patients had an idiopathic EOS while ten patients had a neuromuscular or syndromic EOS (seven spinal muscular atrophy (SMA) and three with cerebral palsy or a syndrome). Their mean ages at surgery were 7.1 years (SD 2.2) and 13.3 years (SD 2.6) respectively at final follow-up. The mean preoperative Cobb angle of the major curve was 66.1° (SD 8.5°) and had improved to 25.5° (SD 9.9°) at final follow-up. The T1 to S1 length increased from 289.7 mm (SD 24.9) before surgery to 330.6 mm (SD 30.4) immediately after surgery. The mean T1 to S1 and T1 to T12 growth after surgery were 64.1 mm (SD 19.9) and 47.4 mm (SD 18.8), respectively, thus accounting for a mean T1 to S1 and T1 to T12 spinal growth after surgery of 10.5 mm/year (SD 3.7) and 7.8 mm/year (SD 3.3), respectively. A total of six patients (five idiopathic EOS, one cerebral palsy EOS) had broken rods during their growth spurt but were uneventfully revised with a fusion procedure. No other complications were noted. Our data show that SGR is a safe and effective technique for the treatment of EOS in nonambulatory hypotonic patients with a neuromuscular condition. Significant spinal growth can be expected after surgery and is comparable to other published techniques for EOS. While satisfactory correction of the deformity can be achieved and maintained with this technique, a high rate of rod breakage was seen in patients with an idiopathic or cerebral palsy EOS. Cite this article: Bone Joint J 2020;102-B(11):1560-1566.

ALIGNING METHOD OF STRUCTURES DURING INSTALLATION IN VERTICAL PLANE

This article presents the results of the research methods of structures aligning during installation in the vertical plane. The analysis and research of existing methods of structures alignment in the vertical plane, used in the conditions of enterprises engaged in the installation of metal tanks. The results of the research showed that the applied alignment methods in the vertical plane have some drawbacks, in particular, after aligning, additional calculations are required. And also for alignment of sliding timbering, columns and wall panels use some theodolites, including vertical allotment. Laser devices and theodolites with visual system were also investigated. However, all the methods considered with the use of these devices are quite time-consuming and a significant number of tools and equipment are used. A device is proposed to control the shape and location of flat surfaces using the principle of similarity of triangles allowing obtaining a straight line of intersection of lasers in space parallel to the plumb line. Developed devices are cheap, easy to use and manufacture. With the use of the proposed technique, there is no need to use several working and expensive devices. The developed devices can significantly reduce the alignment time of building structures in the vertical and horizontal planes.

A novel radiological projection of the pelvis to evaluate the sitting imbalance in pelvis nonunions and malunions

IntroductionInadequate initial management of unstable pelvic injuries is usually associated with a fracture non-union and/or mal-union. Complete clinical and imaging evaluation is mandatory for a correct preoperative planning. Among other symptoms, sitting discomfort may arise from asymmetry of the ischial tuberosities or pressure from a prominent bony projection. Conventional radiographs are usually taken with the individual in a supine position and not in position where the symptoms are referred. We attempted to define a new radiological projection different than the regular pelvis views to study the position of pelvis of a normal person in sitting position. The second objective was to demonstrate its utility in the evaluation of a pelvic deformity. Material and methodsFifteen healthy individuals were evaluated with a radiological projection in a sitting position. One patient with a vertically migrated pelvis nonunion was also evaluated with the same radiological protocol. ResultsIn each volunteer’s radiological study, a parallel line could be drawn between the sitting table and both distal aspects of the ischial tuberosities, sacral alas and superior aspect of the iliac wings. A plumb line perpendicular to the above mentioned ones could be drawn uniting the vertebras’ spinous processes. A 90⁰ line intersection confirms the absence of deformity. In the pathological case, a pseudo scoliosis of the thoracolumbar spine is detected trying to compensate the pelvis obliquity and maintain equilibrium. ConclusionsWe determined normal and pathological radiological features in the sitting imbalance of the pelvic in the anteroposterior plane of the pelvis. The study helps to understand the biomechanics and compensation of the pelvis to define surgical indications and predict post correction anatomy.

Problem of the Vertical Deflection in High-Precision Inertial Navigation

The paper addresses the systematic error of an inertial navigation system, caused by the discrepancy between the plumb line and the normal to the reference ellipsoid surface. The methods of this discrepancy estimation, and their use for correcting the output data of inertial navigation systems are studied.

Orientation of L4 coronal tilt relative to C7 plumb line as a predictor for postoperative coronal imbalance in patients with degenerative lumbar scoliosis

The study design is case–control. To evaluate the impact of preoperative coronal patterns based on the relationship between orientation of L4 coronal tilt and C7 plumb line on immediate postoperative coronal imbalance in degenerative lumbar scoliosis (DLS) patients. Although lumbosacral fractional curve has been long stressed in correction surgery of DLS, there is paucity of literature focusing on preoperative coronal pattern based on the relationship between orientation of L4 coronal tilt and C7 plumb line and its impact on immediate postoperative coronal imbalance in DLS patients. A consecutive series of DLS patients who underwent deformity correction surgery via posterior-only approach were reviewed. According to the relationship between orientation of L4 coronal tilt and C7 plumb line preoperatively, a total of 77 DLS patients who underwent posterior spinal corrective surgery were classified into: 1. Coronal consistency pattern, L4 coronally tilts toward C7 plumb line; 2. Coronal opposition pattern, L4 coronally tilts opposite C7 plumb line. Coronal imbalance was defined as global coronal malalignment (GCM) on either side more than or equal to 20 mm. Whole-spine standing radiographs of both pattern groups were assessed preoperatively and postoperatively. There were 37 patients with coronal consistency pattern and 40 patients with coronal opposition pattern. Compared to patients with coronal opposition pattern, patients with coronal consistency pattern had significantly higher postoperative GCM (P = 0.028), lower amount of GCM correction (P = 0.013) and higher incidence of postoperative coronal imbalance (P = 0.001); further logistic regression analysis revealed coronal consistency pattern was associated with increased odds of postoperative coronal imbalance (odds ratio: 5.981; 95% confidence interval 2.029–17.633; P = 0.001). DLS patients with preoperative coronal consistency pattern carried greater risk for immediate postoperative coronal imbalance following posterior long correction surgery.Level of evidence 3

Efficacy and radiographic analysis of oblique lumbar interbody fusion in treating lumbar degenerative spondylolisthesis with sagittal imbalance.

The aim of this study was to evaluate the effectiveness of OLIF (oblique lumbar interbody fusion) in the treatment of lumbar degenerative spondylolisthesis with sagittal imbalance. Fifty-nine patients were included in our analysis. Included patients were divided into 2 groups according to the surgical techniques: PLIF (posterior lumbar interbody fusion) (n = 31) and OLIF + PSF (OLIF combined with posterior spinal fixation) (n = 28). Perioperative radiographic parameters, complications, and clinical outcome from each group were assessed and compared. The operation time for both groups was 165.1 min in the OLIF group and 182.1 min in the PLIF group (P < 0.05). The intraoperative blood loss was 190.6 ml in the OLIF group and 356.3 ml in the PLIF group (P < 0.05). The number of intraoperative and postoperative complications for both groups was 7 in the OLIF group and 11 in the PLIF group. Significant clinical improvement was observed in VAS scores and ODI when comparing preoperative evaluation and final follow-up. The preoperative SVA (the distance from the posterosuperior corner of S1body to the C7 plumb line), PI (pelvic incidence), LL (lumbar lordosis), PI-LL mismatch, DH (disc height), and lumbar Cobb angles of both groups were similar. The postoperative and final follow-up SVA, LL, PI-LL mismatch, and disc height were improved in both groups, and a statistical difference was found between both groups (P < 0.05). An improvement of SVA, LL, PI-LL mismatch, and disc height at the OLIF group was better than that found at the PLIF group. An improvement in radiographic and clinical outcomes for the OLIF group was better than that seen for the PLIF group. Then, OLIF had a more curative effect in lumbar degenerative spondylolisthesis with sagittal imbalance.

29. C2 SVA: when angles are too complicated and the X-ray image is too small

BACKGROUND CONTEXT The cranial sagittal vertical axis (CrSVA) and the cranial gravity line (CrGL), respectively defined as vertical plumb lines from the center of the skull to the posterior sacral vertical line and the center of the femoral heads/hip axis, are superior to the C7 SVA and better predict HRQOL. The T1 pelvic angle (T1PA) is an angular parameter that obviates the need to account for compensatory mechanisms distally such as knee flexion. Global tilt (GT) is another angular parameter and is an important feature of the GAP score. Long cassette films that incorporate the femoral heads and the skull simultaneously are often difficult to obtain, especially in the intraoperative setting. We sought to study other possible substitutes for the CrSVA and CrGL that could be applied in the setting of more limited radiographic resources. PURPOSE C2 SVA, which requires neither skull nor femoral heads, will provide statistically significant correlation to health-related quality of life measures (HRQOL) and to previously established sagittal plumb line and global angular sagittal parameters. STUDY DESIGN/SETTING Retrospective observational cohort. PATIENT SAMPLE A cohort of 53 operative patients including adult and adolescent deformity cases were selected and analyzed. OUTCOME MEASURES Preoperative baseline sagittal parameters, including C2SVA, C2GL, C7SVA, CrSVA, CrGL, T1PA, as well as baseline preoperative SRS-22 and ODI. METHODS A cohort of 53 operative patients including adult and adolescent deformity cases were selected and analyzed for preoperative baseline sagittal parameters, including C2SVA, C2GL, C7SVA, CrSVA, CrGL, T1PA, as well as baseline preoperative SRS-22 and ODI. Pearson's r was used to quantify the correlation. RESULTS The C2SVA has a statistically significant correlation with the CrGL [r(51)=0.87; p CONCLUSIONS Validated angular parameters of T1PA and GT have the highest correlation with each other and with SRS-22 and ODI. among plumb line parameters, the C2 SVA has the highest correlation with the T1PA, GT, ODI and SRS-22 scores. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Free-hand technique of S(2) alar iliac screw placement for sacropelvic fusion in lumbar degenerative scoliosis

Objective: To evaluate the feasibility of placement of S(2) alar iliac screw (S(2)AI) using free-hand technique for sacrapelvic fusion in lumbar degenerative scoliosis. Methods: Eighteen patients with Lumbar Degenerative Scoliosis treated by S(2)AI screw fixation at Department of Orthopedics, General Hospital of Southern Theater Command of People's Liberation Army and Department of Orthopedics, 89th hospital of People's Liberation Army from August 2014 to October 2018 were analyzed retrospectively. There were 5 males and 13 females, aged 63.2 years old (range:55 to 71 years old).Parameters of spine including: Cobb Angle, C(7) plumb line -center sacral vertical line (C(7)PL-CSVL), lumbar lordosis(LL), sagittal vertical axis(SVA), pelvic incidence(PI), pelvic tilt(PT), sacral slope (SS) and pI-LL were measured on the whole spine X-ray before operation and at final follow-up. Pelvic CT scan was performed postoperatively to assess the accuracy of S(2)AI placement. Oswestry disability Index (ODI) was also recorded. The data were compared by paired t test or Wilcoxon tests. Results: All patients were followed up for 23.7 months (range: 12~62 months).At the last follow up, Cobb Angle decreased from (32.28±4.97) °preoperative to (6.56±3.20) ° (t=41.142, P<0.01) and C(7)PL-CSVL deceased from (1.11±2.07) cm preoperative to (0.18±1.08) cm (t=41.142, P=0.06) .LL improved from (-22.39±13.07) °preoperative to (-36.39±4.29) ° (t=4.470, P<0.01) , PI-LL decreased from (26.83±14.83)°preoperative to (13.72±8.3)° (t=4.396, P<0.01) , PT decreased from (27.94±4.26) °to (23.39±6.08) ° (t=2.680, P=0.02) , and SS increased from (22.22±6.36) °to (26.28±7.24) ° (t=-2.178, P=0.04) .SVA decreased from (6.54±4.51) cm preoperative to (2.62±1.29) cm (t=3.052, P=0.01) .ODI decreased from 0.58(0.40) (M(Q(R))) to 0.18 (0.15) (Z=-4.567, P<0.01) .No complications such as nerve and blood vessel injury occurred during the operation. A total of 32 S(2)AI screws were placed, 3 screws were placed with mild to moderate cortical breaches, 2 were perforated the pelvis ventrally, 1 was perforated posteriorly, with no clinically notable neurovascular or visceral complications. Eight patients finished the SRS-22 questionnaire, with mean score of 4.4 in terms of satisfaction with management. Conclusions: Free-hand technique of S(2)AI screw placement for sacrapelvic fusion in degenerative lumbar scoliosis is safe and feasible.S(2)AI fixation in DLS can provide great correction of deformity, maintain the stability of lumbo-pelvic area and improve the clinical symptoms.

283. The position of the L1 vertebra relative to the gravity line does not appear to correlate with proximal junctional kyphosis following adult spinal deformity surgery with two year follow up

BACKGROUND CONTEXT It is known that upper instrumented vertebrae (UIV) position relative to sagittal vertical axis (SVA) is associated with PJK. Over correction of the lumbar spine, resulting in posterior displacement of L1 relative to the GL, may be associated with PJK. PURPOSE Patients who are over corrected with hyper-lordotic spines may develop junctional problems because of forward compensatory leaning of the thoracic spine. Because L1 represents the thoracolumbar junction, its position relative to the gravity line (GL) may correlate with proximal junctional kyphosis (PJK). We investigated if the sagittal position of L1 relative to the GL correlates with PJK. STUDY DESIGN/SETTING Retrospective study. PATIENT SAMPLE Patients who undergoing ASD correction ≥6 levels from the lower thoracic (LT) spine to S1 with a minimum 2-year follow-up were reviewed. OUTCOME MEASURES Demographic data and radiographic spinopelvic parameters included: pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), PI–LL, sacral slope (SS), T1 pelvic angle (TPA), L1 pelvic angle (L1PA), T5-T12 thoracic kyphosis (TK), sagittal vertical axis (SVA) and L1-GL (cm). METHODS Patients who undergoing ASD correction ≥6 levels from the LT spine to S1 with a minimum 2-year follow-up were reviewed. Demographic data and radiographic spinopelvic parameters included: PI, PT, LL, PI–LL, SS, TPA, L1PA, TK, SVA and L1-GL (cm). GL is defined as the plumb line from external auditory canal. L1-GL is the distance from the center of L1 to GL. RESULTS A total of 76 patients met inclusion criteria including 36 patients with PJK and 40 patients without PJK, with a minimum 2-year follow up. There was no difference in age, gender, and follow-up time in the two groups. There was no statistical difference between groups with regard to PI, SS, PT, LL and TPA (P > 0.05). Preoperative L1PA was 16.00 ± 9.97°for PJK group and 15.75 ± 8.89° for non- PJK group (P =0.914). Preoperative L1-GL was 8.94 ± 6.45 cm for PJK group and 7.09 ± 5.43 cm for non-PJK group (P =0.178). Postoperative L1PA was 13.95 ± 6.76° for PJK group and 14.17 ± 9.35° for non-PJK group (P =0.908). Preoperative L1-GL was 6.00 ± 4.02 cm for PJK group and 7.6 ± 5.38 cm for non-PJK group (P =0.994). CONCLUSIONS The position of L1 vertebra relative to the gravity line does not appear to correlate with PJK after ASD surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. It is known that upper instrumented vertebrae (UIV) position relative to sagittal vertical axis (SVA) is associated with PJK. Over correction of the lumbar spine, resulting in posterior displacement of L1 relative to the GL, may be associated with PJK. Patients who are over corrected with hyper-lordotic spines may develop junctional problems because of forward compensatory leaning of the thoracic spine. Because L1 represents the thoracolumbar junction, its position relative to the gravity line (GL) may correlate with proximal junctional kyphosis (PJK). We investigated if the sagittal position of L1 relative to the GL correlates with PJK. Retrospective study. Patients who undergoing ASD correction ≥6 levels from the lower thoracic (LT) spine to S1 with a minimum 2-year follow-up were reviewed. Demographic data and radiographic spinopelvic parameters included: pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), PI–LL, sacral slope (SS), T1 pelvic angle (TPA), L1 pelvic angle (L1PA), T5-T12 thoracic kyphosis (TK), sagittal vertical axis (SVA) and L1-GL (cm). Patients who undergoing ASD correction ≥6 levels from the LT spine to S1 with a minimum 2-year follow-up were reviewed. Demographic data and radiographic spinopelvic parameters included: PI, PT, LL, PI–LL, SS, TPA, L1PA, TK, SVA and L1-GL (cm). GL is defined as the plumb line from external auditory canal. L1-GL is the distance from the center of L1 to GL. A total of 76 patients met inclusion criteria including 36 patients with PJK and 40 patients without PJK, with a minimum 2-year follow up. There was no difference in age, gender, and follow-up time in the two groups. There was no statistical difference between groups with regard to PI, SS, PT, LL and TPA (P > 0.05). Preoperative L1PA was 16.00 ± 9.97°for PJK group and 15.75 ± 8.89° for non- PJK group (P =0.914). Preoperative L1-GL was 8.94 ± 6.45 cm for PJK group and 7.09 ± 5.43 cm for non-PJK group (P =0.178). Postoperative L1PA was 13.95 ± 6.76° for PJK group and 14.17 ± 9.35° for non-PJK group (P =0.908). Preoperative L1-GL was 6.00 ± 4.02 cm for PJK group and 7.6 ± 5.38 cm for non-PJK group (P =0.994). The position of L1 vertebra relative to the gravity line does not appear to correlate with PJK after ASD surgery.

135. Multicenter prospective assessment of outcomes and complications associated with adult spinal deformity surgery in 62 patients with severe global coronal malalignment

BACKGROUND CONTEXT Substantial adult spinal deformity (ASD) research has focused on sagittal plane radiological assessment and emphasized the importance of sagittal correction on patient-reported outcomes. It seems less attention has been given to evaluation of ASD in the coronal plane. However, recent ASD studies have demonstrated baseline global coronal malalignment (GCM; substantial displacement of the C7 coronal plumb line from midsacrum) in up to 35% of patients. Moreover, GCM can worsen postoperatively or may occur as an iatrogenic complication in previously balanced patients. Collectively, this may suggest that the associated clinical impact of GCM on ASD surgical outcomes has been underestimated. Currently, few reports focus on surgical outcomes in ASD patients with GCM. PURPOSE Our objective was to assess treatment outcomes and complication rates associated with ASD surgery in the subset of patients with severe GCM. STUDY DESIGN/SETTING Retrospective review of a prospectively collected multicenter consecutive case registry. PATIENT SAMPLE Enrollment required: age ≥18 years, scoliosis ≥20°, sagittal vertical axis (SVA) ≥5cm, pelvic tilt ≥25°, and/or thoracic kyphosis ≥60°. OUTCOME MEASURES Radiographic correction (both standard coronal and sagittal spinopelvic deformity measurements) and health-related quality of life (HRQL) outcomes, which included Oswestry Disability Index (ODI), Short Form-36 (SF-36) scores, Scoliosis Research Society-22 (SRS-22) scores, and back/leg pain numerical rating scale (NRS) scores. METHODS Surgically treated ASD patients with severe GCM (coronal C7PL-midsacral offset magnitude ≥1 SD above the mean) were identified. Baseline and follow-up radiographic and HRQL outcomes were analyzed. Percentages of patients achieving minimal clinically important difference (MCID) and substantial clinical benefit (SCB) were assessed. Demographic, frailty, surgical, and complications data were collected. The primary focus for analysis was on patients who reached minimum 2-year follow-up. RESULTS Of 691 potentially eligible operative patients (mean GCM = 4±3 cm), 80 met criteria for severe GCM ≥ 7cm. Of these 80 patients, 62 (78%, mean age 64 years, 81% women) had minimum 2-year follow-up. Baseline frailty score was 3.9±1.5 (indicating patients were frail) and 48% had prior spine fusion. Surgical data included: posterior-only (58%), mean fusion 13 levels, sacroiliac fixation (97%), and three-column osteotomy (36%). Postoperative biplane alignment improved significantly (p CONCLUSIONS ASD surgery for patients with severe GCM is associated with significant improvements in biplane alignment and HRQL outcome measures despite high complication rates. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

217. Outcomes of surgical treatment for patients with mild scoliosis and age appropriate sagittal alignment with minimum 2-year follow up

BACKGROUND CONTEXT Operative treatment of adult spinal deformity (ASD) can be very challenging with high complication rates. Despite these challenges it's well established that pts benefit from such treatment. However, the surgical outcomes for pts with mild scoliosis and age appropriate sagittal alignment have not been reported. PURPOSE To determine if patients (pts) with mild scoliosis and age appropriate sagittal alignment have favorable outcomes following surgical correction. STUDY DESIGN/SETTING Retrospective review of a prospective, multicenter ASD database. PATIENT SAMPLE ASD patients: operative pts age≥18, and all preoperartive pelvic tilt (PT), mismatch between pelvic incidence and lumbar lordosis (PI-LL), and C7 sagittal vertical axis (SVA) within established age adjusted parameters with minimum 2-year follow up. A subanalysis for pts with max coronal cobb angle 10-30° (mild scoli) was done. OUTCOME MEASURES Health-related quality of life (HRQOL) scores: Oswestry Disability Index (ODI), Short form-36(SF36), Scoliosis Research Society (SRS22), back/leg pain numerical rating scale (NRS) and minimum clinically important difference (MCID)/substantial clinical benefit (SCB). Radiographic values: max coronal cobb angle, coronal C7 plumb line, PT, PI-LL, thoracic kyphosis (TK), SVA. Demographic, frailty, surgical and complications data were collected. METHODS Two-year and baseline HRQOL/radiographic data were compared. RESULTS A total of 103 pts were included from 667 operative patients (89.3% female, avg age 59.8±13.1yrs). Of the 103 pts, 29 (28.2%) had max preop coronal cobb angle 10-30°. Two-year max coronal cobb angle and C7 coronal plumb were significantly improved compared to baseline (p CONCLUSIONS Pts with mild scoliosis and sagittal alignment within age appropriate parameters benefit from surgical correction at 2 years postop both radiographically and clinically including 81.5% meeting MCID for SRS pain despite having high complication rates. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

30. Retrospective comparative analysis of combined vs only posterior approach for treating severe scoliosis

BACKGROUND CONTEXT Studies comparing two-stage approach (first anterior then posterior) and only posterior approach for treating scoliosis are rather scarce, with shorter follow-up and lack of clinical data. PURPOSE The purpose of the retrospective study was to compare long-term clinical and radiological outcomes in comparable groups of patients when using different surgical approaches (two-stage and only posterior) for idiopathic scoliosis operations. STUDY DESIGN/SETTING A retrospective, one center, institutional review board approved study. PATIENT SAMPLE A total of 348 patients with idiopathic scoliosis were operated on using CD hybrid instrumentation with pedicle screw and hooks. Only patients with curvatures ≥61 ° were analyzed and divided in two groups: two-stage surgery (N=30) and one-stage surgery (N=46). OUTCOME MEASURES Not applicable. METHODS Comparisons between groups were made regarding the following variables: gender, age at surgery, follow-up duration, number of segments, duration of surgery, hospitalization time, and different radiological parameters. The anteroposterior (AP) and lateral standing radiographs were used to check for deformity; numbers of instrumented segments, curve flexibility (bending test), coronal and sagittal balance and rotation deformity. The coronal balance was measured as the distance between the C7 plumb line and the perpendicular line drawn from the center of S1. The sagittal balance was measured as shortest distance between the C7 plumb line and the posterior superior corner of the S1 body. For both coronal and sagittal measurements, balance was considered abnormal if the distance was greater than 2 cm. Measurement of vertebral rotation was done using the Nash-Moe method. All patients were invited in an outpatient clinic to fill out a short-form health survey (SF-36) and to make a control X-ray image of the whole spine. RESULTS No statistically significant difference was observed in correction between two-stage group (average correction 69%) and only posterior approach group (average correction 66%). However, there were statistically significant differences regarding hospitalization time, duration of the surgery and the number of instrumented segments. The SF-36 scores were similar and there were no statistically significant differences between different health dimensions among compared groups. The greatest differential found in mean scores was for energy and vitality. CONCLUSIONS Two-stage surgery has only a limited advantage in terms of postoperative correction angle compared to the posterior approach. Posterior instrumentation and correction is satisfactory, especially taking into account that the patient is subjected to only one surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Sagittal Spinopelvic Translation Is Combined With Pelvic Tilt During the Standing to Sitting Position: Pelvic Incidence Is a Key Factor in Patients Who Underwent THA

BackgroundSagittal spinopelvic translation (SSPT) is the horizontal distance from the hip center to the C7 plumb line (C7PL). SSPT is an important variable showing the overall patient balance in different functional positions which could affect the rate of hip instability. This study investigates the SSPT modification in patients who underwent total hip arthroplasty (THA). MethodsA total of 120 patients were assessed preoperatively and postoperatively on standing and sitting acquisitions (primary unilateral THA without complication). SSPT is zero when the C7PL goes through the center of the femoral heads and positive when the C7PL is posterior to the hips’ center (negative if anterior). Three subgroups were defined based on the pelvic incidence (PI): low PI <45°, 45°< normal PI <65°, or high PI >65°. ResultsThe overall mean preoperative SSPT change from standing to sitting was 2.2 cm ([-7.2 to 17.4]) (P < .05). The overall mean postoperative SSPT change from standing to sitting was 1.2 cm ([-14.2 to 22.4]) (P < .05). In low- and normal-PI groups, standing to sitting SSPT and preoperative to postoperative changes in standing SSPT were increased significantly after surgery with the C7PL behind the hips’ center (P < .05). In the high-PI group, standing to sitting SSPT was increased postoperatively (P = .034) (no significant changes from preoperative to postoperative status in standing and sitting). ConclusionsAdaptation from standing to sitting positions combines pelvic tilt and anteroposterior pelvic translation. THA implantation induces significant changes in SSPT mainly for low- and standard-PI patients. This is an important variable to consider when investigating the causes of THA subluxation or dislocation.

Postoperative spino-pelvic stereoradiography to predict adjacent segment disease

PurposeThe purpose of this study was to identify sagittal spinopelvic parameters predictive of adjacent segment disease (ASD) on postoperative whole spine weight-bearing stereoradiography. Materials and methodsA total of 84 patients with previous spinal fusion surgery and documented radiological follow-up with early weight-bearing postoperative whole spine stereoradiography (EOS® Imaging System) were retrospectively included. A pathological group of 42 patients (9 men, 33 women; mean age, 63.1±11.5 [SD] years) who developed documented ASD (mean follow-up, 76.75 months; range: 31.5–158.5 months) was compared with a control group of 42 asymptomatic patients (7 men, 35 women; mean age, 60.9±11.8 [SD] years) (mean follow-up, 115 months; range: 60–197 months) based on sagittal balance evaluation and routinely used spino-pelvic parameters. Comparisons were made using uni- and multivariate analyses. ResultsAt univariate analysis, patients with ASD had an anteriorly displaced sagittal vertical axis (CAM plumb line) and an inadequate lumbar lordosis (LL) in reference to pelvic incidence (PI) compared to controls. They also had higher C7 slope and C2-C7 offset. At multivariate analysis, C2-C7 offset (OR=1.152; 95% CI: 1.056–1.256; P=0.001) and a lack of LL (OR=5.063; 95% CI: 1.139–22.498; P=0.033) were significantly associated with ASD. ConclusionAnterior cervical imbalance, reflected by an increase in C2-C7 offset and insufficient restoration of LL are postoperative predictive factors of ASD on stereoradiography.

Development of an Automatic System for Detection Plumb line and Alignment of Elevator Guide Rails

Alignment of Guide Rails takes up majority of the time in the process of Elevator Installation. The conventional methods are manual and time consuming and their accuracy highly depends on the accuracy of measurement of the installing workmen. Development of an Automatic system for detecting the plumb line and alignment of guide rails, which involves no human intervention, will improve work efficiency, accuracy and eventually lead to faster installation processes.

The Impact of Posterior Spinal Fusion (PSF) on Coronal Balance in Adolescent Idiopathic Scoliosis (AIS): A New Classification and Trends in the Postoperative Period.

One of the primary goals of scoliosis surgery is to balance the head over the pelvis (or avoid creating imbalance). Historically, a normal coronal balance was defined as the C7 plumb line (C7PL) within 2 cm of the central sacral vertical line (CSVL); however, there is limited published information regarding the speed/magnitude and success/failure of balancing, rebalancing, or unbalancing in the postoperative period. The purpose of this study is to classify and quantify coronal plane balance postoperatively in adolescent idiopathic scoliosis when using pedicle screw instrumentation. Evaluated patients with adolescent idiopathic scoliosis who had a posterior spinal fusion withstanding 2-view, posteroanterior and lateral radiographs of the entire spine performed at first erect visit, 6, 12, and 24 months. To measure coronal balance, a C7PL was measured and compared with the CSVL. A negative value denotes the leftward deviation of the C7PL and a positive value a rightward deviation. The authors then created a novel coronal balance classification system. A total of 954 patients met the inclusion criteria. There was a strong trend toward improving coronal balance, especially between first erect and 6 months; the proportion of out of balance patients declined throughout the 2-year period: preoperative 372 of 954 (39%), first erect 297 of 954 (31.1%), 6 months 167 of 954 (17.5%), 1 year 136 of 954 (14.3%), and 2 years 115 of 954 (12.0%). Analyzing the patients most out of balance immediately after posterior spinal fusion, 35 of 50 (70%) in group 3 regained balance by 2 years. Out of the remaining 15 patients, 12 corrected to group 1 (24%), 2 patients to group 2 (4%), and 1 patient remained in group 3 (2%). This large, longitudinal postoperative study of coronal balance documents a strong trend toward postoperative rebalancing, with the largest gains between first erect image and 6 months. The 31% of patients out of balance at first erect declined to only 12.1% at 2 years.

Comparison of Ultrasonic Thickness of Masseter Muscle Between Individuals With and Without Severe Forward Head Posture: A Cross-Sectional Study

ObjectiveIn this cross-sectional descriptive-analytical study, we sought to compare the ultrasonic thickness of the masseter muscle in people with severe forward head posture vs people without forward head posture, and to determine sex differences in muscle thickness. MethodsThirty-eight volunteers (19 with normal head postures and 19 with severe forward head postures), aged 18 to 35 years, entered the study. The severity of the forward head posture was measured by a plumb line and the craniovertebral angle drawn on the recorded images. Based on the recorded images, the masseter muscle thickness was also measured by a 7.5-MHz linear transducer using an ultrasound device in the seated position with 3 mouth positions (closed, half open, and fully open). ResultsThe results showed that the head posture affects masseter thickness significantly (P = .01), with masseter thickness significantly lower in the participants without severe forward head postures compared to those with severe forward head postures in the closed, half-open, and fully open mouth positions (P < .05). Comparing the mean masseter thickness across sexes showed that the masseter muscle is significantly thicker in men compared to women (P = .01). ConclusionHead posture and thickness of the masseter muscle are linked, as the masseter muscle was thicker in all 3 positions in the participants with severe forward head postures.