Adjacent Segment Disease after Long Spinal Fusion Ending at L5 for Adult Spinal Deformity: A Retrospective Cohort Study

Study Design: This is a retrospective cohort study using data from the adult spinal deformity (ASD) database of a single institution. Purpose: To investigate the incidence of proximal junctional failure and distal junctional failure (DJF) after ASD surgery with a lower instrumented vertebra (LIV) at L5. Overview of Literature: Spinopelvic fixation from the lower thoracic vertebra to the pelvis is the current gold standard treatment for ASD. However, the LIV at L5 is acceptable in some cases. Methods: Fifty-six patients who underwent corrective surgery for ASD with LIV at L5 were included. The upper instrumented vertebra (UIV) was T7 in one patient, T9 in 14, T10 in three, T11 in four, T12 in eight, L1 in 10, and L2 in 16. Regarding clinical parameters, age, sex, curve types of Scoliosis Research Society-Schwab classification, number of levels fused, follow-up period, hip bone mallow density, revision surgery rate, and radiographic measurements were compared between the T (UIV: T7 - 10) and TL (UIV: T11 - L2) groups. Results: The revision surgery rate was 19.6% overall. In the T and TL groups, it was 27.8%, and 15.8%, respectively (p = 0.305). The rate of DJF in the T group (33.3%) was significantly higher than in the TL group (5.3%). The rate of proximal junctional kyphosis in the T group (55.6%) was higher than in the TL group (28.9%), with no significant difference. The mean global alignment, sagittal vertical axis, and C7 plumb line-central sacral vertical line were not different between both groups. Conclusions: ASD surgery with LIV set at L5 and UIV set at the thoracic vertebrae (T7 - T10) has a risk of adjacent segment disease.

Spinal deformity measurement using a low-density flexible array ultrasound transducer:A feasibility study with phantoms

Spinal deformities assessment using 3D ultrasound scanning has limitations in fitting onto different back surface contour as well as fitting within the gaps between subject and their spinal brace during bracing assessments.The study proposed a flexible array ultrasound transducer to overcome these limitations.The results demonstrated the feasibility of spinal deformity assessments with a flexible ultrasound array when arranged in four shapes,namely Linear,Concave,Convex,and S-shaped.For comparisons of imaging performance on spinous process using the four shapes,Convex and S-shaped transducer showed a depth dependence and lateral location dependence of the lateral intensity distribution of spinous process,respectively.S-shaped transducer had the least accurate prediction of the location of spinous process,with measurement error of 4.8
3.2 mm,it also showed poorer prediction on spinal curvature measurements.This is suggested to be due to the asymmetrical distortion to the spinous process due to the lateral location dependence of the image.However,the coronal curve prediction of spine phantom performed well with R-squared values of>0.97 in all transducer shapes.The results of this study paved the way for further investigation on the improvement of image quality and measurement accuracy under different shapes for the flexible array,mechanism of dynamic shape change during the scanning to fit different body contour,as well as extension from 1D to 2D flexible array.

Different types of mechanical complications after surgical correction of adult spine deformity with osteotomy

AIM To determine the incidence and risk factors for mechanical complications （MC） after surgical correction of adult spinal deformity （ASD） with osteotomy.METHODSA retrospective study was performed. Inclusion criteria： Surgical correction of ASD using osteotomy; male or female; 〉 20 years old; follow-up ≥ 24 mo or revision. The MC of spine and spinal instrumentation were studied separately. Risk analysis included assessment of the association between more than 50 different characteristics （demographic, clinical, radiographic, and instrumentation） with different types of MC.RESULTSThe medical records of 94 operations in 88 subjects were analyzed： Female （68%）, mean age 58.6 （SD, 12.7） years. Cumulative incidence of MC at 2 year follow-up was 43.6%. Of these, 78% required revision （ P 〈 0.001）. The following characteristics had significant （ P ≤ 0.05） association with MC： （1） Preoperative： osteoporosis, smoking, previous spinal operation, sagittal vertical axis （SVA） 〉 100 mm, lumbar lordosis （LL） 〈 34°; （2） postoperative： SVA 〉 75 mm; operative correction： SVA 〉 75 mm, LL 〉 30°, thoracic kyphosis 〉 25°, and pelvic tilt 〉 9°; a fall; pseudarthrosis; and （3） device and surgical technique： use of previously implanted instrumentation; use of domino and/or parallel connectors; type of osteotomy （PSO vs SPO） if preoperative SVA 〈 100 mm; lumbar osteotomy location; in-situ rod contouring 〉 60°; and fxation to sacrum/pelvis.CONCLUSIONRisk of MC after surgical correction of ASD is substantial. To decrease this risk over- and/or insuffcient correction of the sagittal imbalance should be avoided.

Development of spinal deformities in the tight-skin mouse

Tight-skin （TSK） mice are commonly used as an animal model to study the pathogenesis of Marfan syndrome （MFS）, but little is known of their skeletal phenotype and in particular of the development of the spinal deformities, common in MFS. Here we examined growth of the axial skeletons of TSK and wild-type（B6） mice during their period of rapid growth. The whole bodies of mice, 4-12 weeks of age, were scanned after sacrifice, by micro-computed tomography （microCT）. We reconstructed three-dimensional models of the spine and ribs, and measured vertebral body heights and rib lengths using the Mac-based image-processing software ＂OsiriX＂. Although the TSK mice were smaller than the B6 mice at 4 weeks, they experienced an early growth spurt and by 8 weeks the height, but not the width, of the vertebral body was significantly greater in the TSK mice than the B6 mice. Measurement of the angles of scoliotic and kyphotic curves postmortem in the mice was problematic, hence we measured changes that develop in skeletal elements in these disorders. As a marker of kyphosis, we measured anterior wedging of the vertebral bodies; as a marker for scoliosis we measured asymmetries in rib length. We found, unlike in the B6 mice where the pattern was diffuse, wedging in TSK mice was directly related to spinal level and peaked steeply at the thoracolumbar junction. There was also significant asymmetry in length of the ribs in the TSK mice, but not in the B6 mice. The TSK mice thus appear to exhibit spinal deformities seen in MFS and could be a useful model for gaining understanding of the mechanisms of development of scoliosis and kyphosis in this disorder.

Surgical treatment for scoliosis extending to main thoracic spine by key-vertebral-screws technique (KVST)

Objective:To introduce a key-vertebral-screws technique(KVST) in the surgical treatment of scoliosis extending to main thoracic levels, and to find the role of fulcrum bending in predicting the result of surgical treatment for scoliosis by this technique. Methods: Seventeen consecutive patients with scoliosis extending to main thoracic spine,who underwent pure posterior fusion without anterior or posterior release by KVST between January 2004 and July 2005 were evaluated for fulcrum bending flexibility, surgical correction rate, fulcrum bending correction index (FBCI) in main thoracic curves. Universal Spine System (USS) instrumentation was used in 15 cases,Monarch in another 2 cases. The severity of the curves was measured by Cobb's method using Rad Work 6. 0 software. Preoperative standing AP radiographs, preoperative fulcrum bending anterioposterior (AP) radiographs, postoperative standing AP radiographs, and most recent follow-up standing AP radiographs for spine were measured and recorded. All the data were analyzed with two-sample paired t-test by Origin 7. 0 software. Results: Infection and neurological complications were not noted. No major complications were found. Just one case had some axial back pain, which got a full recovery from physiotherapy for 2 weeks. In the X-ray, there was an average correction of 71. 5% of the fused main thoracic curves, which had no significant lose of correction in final follow-up. For the whole fused main thoracic curves, the fulcrum bending flexibility were lower to operation correction rate (P = 0. 013). The average FBCI was 123%. From the data, the more rigid curves (especially fulcrum bending flexibility <50%), the more correction rate operation could get, compared with fulcrum bending flexibility. Conclusion: (1) KVST is a good method in the surgical treatment of thoracic scoliosis, which can get satisfying result with lower medical cost. (2) Fulcrum bending flexibility is lower than operative correction rate by KVST in main thoracic curves (P<0. 05). In the more rigid curves assessed by fulcrum-bending radiograph, the operative corrective could be gained, especially in the curves which FBCI is lower than 50%.