Prevalence of the thoracic scoliosis in children and adolescents candidates for strabismus surgery: results from a 1935-patient cross-sectional study in China.

PURPOSE: No study so far has paid attention to strabismus-related spinal imbalance. This study aimed to determine the epidemiology of thoracic scoliosis in children and adolescents with strabismus and investigate the association of two diseases. METHODS AND DESIGN: A cross-sectional study. Study group consists of 1935 consecutive candidates for strabismus surgery (4-18 years); Control group consists of the age- and sex-matched patients with respiratory diseases. All subjects underwent a screening program based on chest plain radiographs using the Cobb method. Their demographic information, clinical variables and results of Cobb angle were recorded and analyzed. RESULTS: A significantly higher prevalence of thoracic scoliosis (289/1935, 14.94% versus 58/1935, 3.00%) was found in study group compared with control group. Among strabismic patients, the coronal thoracic scoliosis curve mainly distributed in right and in main thoracic (198/289) and in the curves 10°-19° (224/289); Age range 7-9 years (103/1935), female (179/1935) and concomitant exotropia patients (159/851) were more likely to have thoracic scoliosis. According to the logistic regression, thoracic scoliosis had no significant association with age, BMI, duration of illness and onset age (p > 0.05). However, gender, BCVA, type of strabismus and degree of strabismus showed a significant relationship with the prevalence of thoracic scoliosis (p < 0.05). CONCLUSIONS: With a pooled prevalence of 14.94%, strabismus patients showed a great higher risk of developing thoracic scoliosis. Screening for scoliosis in strabismus patients can be helpful to discover a high prevalence of potential coronal scoliosis. More attention should be paid to ophthalmological problems in patients with scoliosis. These slides can be retrieved under Electronic Supplementary Material.

Factors Associated with Cervical Spine Alignment in an Asymptomatic Population: A Preliminary Analysis.

BACKGROUND: Cervical sagittal imbalance compromises health-related quality of life and can lead to myriad incapacitating symptoms through compression of the spinal cord. Questions regarding which parameters play primary roles in the progression of cervical sagittal imbalance and which might be compensatory factors remain unanswered. METHODS: This study enrolled 246 asymptomatic volunteers from July 2016 to June 2018. After demographic and radiologic parameters were measured, the data were analyzed using correlation coefficient test and multiple regression analysis. A predictive equation was assessed with variance analysis, residual analysis, collinearity analysis, and a paired t test. RESULTS: Average values are as follows: orbital tilt, 64 ± 6°; orbital slope (OS), 15 ± 6°; C0-C2 lordosis (C0C2), 28 ± 8°; cervical lordosis (CL), 5 ± 11°; C2-C7 sagittal vertical axis (C2C7SVA), 15 ± 8 mm; T1 slope (TS), 17 ± 6°; thoracic inlet angle, 69 ± 8°; thoracic kyphosis, 34 ± 9°; lumbar lordosis, 50 ± 10°; sacral slope, 38 ± 7°; pelvic index, 48 ± 9°; sagittal vertical axis, 10 ± 19 mm. Correlations of C2C7SVA were observed with body mass index (BMI), OS, C0C2, CL, and TS. The validated predictive equation was: C2C7SVA = 0.38 × BMI - 0.73 × OS + 0.73 × C0C2 + 0.15 × CL + 0.18 × TS - 6.53. CONCLUSIONS: BMI, OS, C0C2, CL, and TS were primary influencers in the progression of cervical sagittal imbalance and established a predictive equation of asymptomatic population, which can provide clinical advice and remind surgeons of the primary influencers of reconstructive surgery for better prognoses.

Biomechanical properties of novel transpedicular transdiscal screw fixation with interbody arthrodesis technique in lumbar spine: A finite element study.

PURPOSE: The purpose of this study was to investigate finite element biomechanical properties of the novel transpedicular transdiscal (TPTD) screw fixation with interbody arthrodesis technique in lumbar spine. METHODS: An L4-L5 finite element model was established and validated. Then, two fixation models, TPTD screw system and bilateral pedicle screw system (BPSS), were established on the validated L4-L5 finite element model. The inferior surface of the L5 vertebra was set immobilised, and moment of 7.5 Nm was applied on the L4 vertebra to test the range of motion (ROM) and stress at flexion, extension, lateral bending and axial rotation. RESULTS: The intact model was validated for prediction accuracy by comparing two previously published studies. Both of TPTD and BPSS fixation models displayed decreased motion at L4-L5. The ROMs of six moments of flexion, extension, left lateral bending, right lateral bending, left axial rotation and right axial rotation in TPTD model were 1.92, 2.12, 1.10, 1.11, 0.90 and 0.87°, respectively; in BPSS model, they were 1.48, 0.42, 0.35, 0.38, 0.74 and 0.75°, respectively. The screws' peak stress of above six moments in TPTD model was 182.58, 272.75, 133.01, 137.36, 155.48 and 150.50 MPa, respectively; and in BPSS model, it was 103.16, 129.74, 120.28, 134.62, 180.84 and 169.76 MPa, respectively. CONCLUSION: Both BPSS and TPTD can provide stable biomechanical properties for lumbar spine. The decreased ROM of flexion, extension and lateral bending was slightly more in BPSS model than in TPTD model, but TPTD model had similar ROM of axial rotation with BPSS model. The screws' peak stress of TPTD screw focused on the L4-L5 intervertebral space region, and more caution should be put at this site for the fatigue breakage. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: Our finite element study provides the biomechanical properties of novel TPTD screw fixation, and promotes this novel transpedicular transdiscal screw fixation with interbody arthrodesis technique be used clinically.

Acceptable Chin-Brow Vertical Angle for Neutral Position Radiography: Preliminary Analyses Based on Parameters of the Whole Sagittal Spine of an Asymptomatic Chinese Population.

OBJECTIVE: We sought to acquire the whole sagittal spine parameters and investigated the acceptable chin-brow vertical angle (CBVA) for neutral position radiography in an asymptomatic Chinese population. METHODS: The parameters measured in 257 asymptomatic volunteers included CBVA, occipital slope, orbital tilt, occipital incidence, C0-C2 Cobb angle, C2-C7 Cobb angle, C1-C7 Cobb angle, C2-C7 sagittal vertical axis and absolute rotation angle, cervical tilt, cranial tilt, T1 slope, and thoracic kyphosis, and others. We used Pearson correlation analyses to find relationships between CBVA and other variables. The subjects were divided into 5 groups according to the CBVA percentile: group A, 0%-20% CBVA; group B, 20%-40% CBVA; group C, 40%-60% CBVA; group D, 60%-80% CBVA; and group E, 80%-100% CBVA. We used analysis of variance to analyze differences among the 5 groups. RESULTS: Orbital tilt, Occipital incidence, C1-C7 Cobb angle, C2-C7 sagittal vertical axis, and cranial tilt all increased with increasing CBVA (P < 0.001). The occipital slope, C2-C7 Cobb angle, C2-C7 absolute rotation angle, cervical tilt, T1 slope, and thoracic kyphosis decreased with decreasing CBVA (P < 0.05). No correlations between other sagittal parameters and the CBVA were found. A slight deviation was found in groups B-D, with a greater deviation in groups A, C, and E. CONCLUSIONS: An acceptable range of -1.5° to 5.8° is recommended for the CBVA for cervical radiography in the neutral position. When spinal surgeons evaluate the cervical plane, the effects of the CBVA deviation on cervical curvature must be considered.

Rate of presence of 11 thoracic vertebrae and 6 lumbar vertebrae in asymptomatic Chinese adult volunteers.

BACKGROUND: An increasing number of studies on spinal morphology in asymptomatic Asian and Western patients have been reported. Variation in spinal anatomy among patients is considered as the cause of wrong-level surgery in up to 40% of cases. The present study examined the rate of presence of 11 thoracic vertebrae and 6 lumbar vertebrae in 293 asymptomatic Chinese adult volunteers. METHODS: From May 27, 2016, to November 11, 2017, a cohort of 325 asymptomatic Chinese adults meeting the study exclusion criteria was recruited. The radiographs were examined by a spine surgeon and a radiologist to assess the number of thoracic and lumbar vertebrae. RESULTS: In total, 293 volunteers were included in this study: 17 (5.8%) had 11 thoracic vertebrae, and 16 (5.5%) had 6 lumbar vertebrae. Among all volunteers, 12 (4.1%) had 7 cervical vertebrae (C), 11 thoracic vertebrae (T), and 5 lumbar vertebrae (L); 5 (1.7%) had 7C, 11T, and 6L; and 11 (3.8%) had 7C, 12T, and 6L. There was no difference between the findings of the spine surgeon and the radiologist. CONCLUSIONS: For the first time, this study describes the rate of presence of 11 thoracic vertebrae and 6 lumbar vertebrae in 293 asymptomatic Chinese adult volunteers. Variations in the number of thoracic and lumbar vertebrae tend to be ignored by spine surgeons. We encourage spinal surgeons and researchers to be aware of such variations when performing thoracic- and lumbar-level surgery and assessing spinal alignment and parameters.

Does the Iliac Wing Influence L5 Pedicle Screw Fixation?

OBJECTIVE: To explore whether the iliac wing influences L5 pedicle screw (PS) fixation and to propose methods to reduce such influence. METHODS: A total of 100 computed tomography scans (from 50 male and 50 female patients) of the lower lumbar region and pelvis were obtained and 3-dimensionally reconstructed. Cylinders with 6.5-mm diameters were drawn to simulate the different trajectories of L5 PS. The maximum lengths and lateral angles of trajectories, and the vertical distances from the inner edge of the iliac wing to these trajectories, were measured. RESULTS: The maximum lengths and lateral angles differed significantly among trajectories; the maximum length, but not the lateral angle, differed significantly between male and female subjects. The influence of the iliac wing was more significant in male than in female subjects. The iliac wing had a greater effect on screws implanted along the pedicle axis than on screws for which the trajectories commenced at Du's entry point and passed through the center of the pedicle. CONCLUSIONS: This study elucidates the influence of the iliac wing on L5 PS fixation. Careful attention is required when implanting PSs, especially in male patients. The combined use of Du's technique and a percutaneous method for PS implantation effectively reduces the influence of the iliac wing. To minimize the complications of PS fixation further, preoperative simulation of fixation for each patient is very important.