The flying buttress construct for posterior spinopelvic fixation: a technical note

<p>Abstract</p> <p>Background</p> <p>Posterior fusion of the spine to the pelvis in paediatric and adult spinal deformity is still challenging. Especially assembling of the posterior rod construct to the iliac screw is considered technically difficult. A variety of spinopelvic fixation techniques have been developed. However, extreme bending of the longitudinal rods or the use of 90-degree lateral offset connectors proved to be difficult, because the angle between the rod and the iliac screw varies from patient to patient.</p> <p>Methods</p> <p>We adopted a new spinopelvic fixation system, in which iliac screws are side-to-side connected to the posterior thoracolumbar rod construct, independent of the angle between the rod and the iliac screw. Open angled parallel connectors are used to connect short iliac rods from the posterior rod construct to the iliac screws at both sides. The construct resembles in form and function an architectural Flying Buttress, or lateral support arches, used in Gothic cathedrals.</p> <p>Results and discussion</p> <p>Three different cases that illustrate the Flying Buttress construct for spinopelvic fixation are reported here with the clinical details, radiographic findings and surgical technique used.</p> <p>Conclusion</p> <p>The Flying Buttress construct may offer an alternative surgical option for spinopelvic fixation in circumstances wherein coronal or sagittal balance cannot be achieved, for example in cases with significant residual pelvic obliquity, or in revision spinal surgery for failed lumbosacral fusion.</p

The Influence of Spatial Registration on Detection of Cerebral Asymmetries Using Voxel-Based Statistics of Fractional Anisotropy Images and TBSS

The sensitivity of diffusion tensor imaging (DTI) for detecting microstructural white matter alterations has motivated the application of voxel-based statistics (VBS) to fractional anisotropy (FA) images (FA-VBS). However, detected group differences may depend on the spatial registration method used. The objective of this study was to investigate the influence of spatial registration on detecting cerebral asymmetries in FA-VBS analyses with reference to data obtained using Tract-Based Spatial Statistics (TBSS). In the first part of this study we performed FA-VBS analyses using three single-contrast and one multi-contrast registration: (i) whole-brain registration based on T2 contrast, (ii) whole-brain registration based on FA contrast, (iii) individual-hemisphere registration based on FA contrast, and (iv) a combination of (i) and (iii). We then compared the FA-VBS results with those obtained from TBSS. We found that the FA-VBS results depended strongly on the employed registration approach, with the best correspondence between FA-VBS and TBSS results when approach (iv), the “multi-contrast individual-hemisphere” method was employed. In the second part of the study, we investigated the spatial distribution of residual misregistration for each registration approach and the effect on FA-VBS results. For the FA-VBS analyses using the three single-contrast registration methods, we identified FA asymmetries that were (a) located in regions prone to misregistrations, (b) not detected by TBSS, and (c) specific to the applied registration approach. These asymmetries were considered candidates for apparent FA asymmetries due to systematic misregistrations associated with the FA-VBS approach. Finally, we demonstrated that the “multi-contrast individual-hemisphere” approach showed the least residual spatial misregistrations and thus might be most appropriate for cerebral FA-VBS analyses

Comparação do poder de correção do instrumental de Luque-Galveston e do parafuso pedicular no tratamento cirúrgico da escoliose neuromuscular Comparación del poder de corrección del instrumental de Luque-Galveston y del tornillo pedicular en el tratamiento quirúrgico de la escoliosis neuromuscular Comparison between deformity correction of Luque-Galveston instrumentation and pedicle screw fixation in the surgical treatment of neuromuscular scoliosis

OBJETIVO: avaliar o poder de correção do parafuso pedicular em comparação ao sistema de Luque-Galveston no tratamento cirúrgico da escoliose neuromuscular. MÉTODOS: foram avaliados 74 pacientes submetidos à artrodese exclusivamente pela via posterior, estendendo-se da região torácica alta ao sacro. Vinte e quatro pacientes foram submetidos à fixação com sistema de Luque-Galveston (Grupo 1) e 50, com parafusos pediculares (Grupo 2). Foram avaliadas as radiografias pré-operatórias, em tração e no pós-operatório imediato e mediu-se o valor da curva principal do período pré-operatório (Cobb pré), na tração (Cobb tração), e no pós-operatório (Cobb pós), e calculou-se a flexibilidade da curva e a correção final. Também foi calculado o Índice de Cincinnati, que leva em consideração a correção final e a flexibilidade (Cincinnati = Correção/Flexibilidade). Os mesmos parâmetros foram calculados para a obliquidade pélvica (OP): OP pré, OP tração, OP pós, Flexibilidade OP, Correção OP e Índice de Cincinnati para OP. RESULTADOS: a média da idade dos pacientes do Grupo 1 foi de 12,24 anos e do Grupo 2, de 16,13 anos (p=0,001). No Grupo 1, a principal doença foi a amiotrofia espinhal (38%) e no Grupo 2, a paralisia cerebral (62%). O ângulo de Cobb pré foi de 76,67º para o Grupo 1 e 85,54º para o Grupo 2. A flexibilidade foi de 45,32% para o Grupo 1 e 39,47% para o Grupo 2. A Correção foi de 63,07% para o Grupo 1 e 59,80% para o Grupo 2. O índice de Cincinnati para o Grupo 1 foi de 1,44 e de 1,71 para o Grupo 2. Quanto à OP, tivemos OP pré de 20,71º para o Grupo 1 e 26,60º para o Grupo 2. A Flexibilidade OP foi de 73,61% para o Grupo 1 e 56,54% para o Grupo 2 (p=0,047). A Correção OP foi de 73,47% para o Grupo 1 e de 72,11% para o Grupo 2. O Índice de Cincinnati da OP foi de 1,09 e 1,49, respectivamente para os Grupos 1 e 2 (p=0,045). CONCLUSÕES: a instrumentação com parafusos pediculares mostrou correção da escoliose semelhante à fixação com Luque-Galveston e maior poder de correção da obliquidade pélvica no tratamento das deformidades neuromuscluares.<br>OBJETIVO: evaluar el poder de corrección del tornillo pedicular comparado al sistema de Luque-Galveston en el tratamiento quirúrgico de la escoliosis neuromuscular. MÉTODOS: fueron evaluados 74 pacientes sometidos a la artrodesis exclusivamente por la vía posterior, extendiéndose de la región torácica alta a la sacra. De estos pacientes, 24 fueron sometidos a la fijación con sistema de Luque-Galveston (Grupo 1) y 50 con tornillos pediculares (Grupo 2). Fueron evaluadas las radiografías preoperatorias, en tracción y en el postoperatorio inmediato, además de medido el valor de la curva principal preoperatoria (Cobb pre), en tracción (Cobb tracción) y en el postoperatorio (Cobb post). También fue calculada la flexibilidad de la curva y la corrección final. Fue calculado el índice de Cincinnati que lleva en consideración la corrección final y la flexibilidad (Cincinnati=corrección/flexibilidad). Los mismos parámetros fueron calculados para la oblicuidad pélvica (OP): OP pre, OP tracción, OP post, flexibilidad OP, corrección OP e índice de Cincinnati para OP. RESULTADOS: el promedio de edad de los pacientes del Grupo 1 fue de 12.24 años y del Grupo 2 de 16.13 años (p=0.001). En el Grupo 1, la principal patología fue la amiotrofia espinal (38%) y en el Grupo 2, la parálisis cerebral (62%). O Cobb pre fue de 76.67º para el Grupo 1 y 85.54º para el Grupo 2. La flexibilidad fue de 45.32% para el Grupo 1 y 39.47% para el Grupo 2. La corrección fue de 63.07% para el Grupo 1 y 59.80% para el Grupo 2. El índice de Cincinnati para el Grupo 1 fue de 1.44 y de 1.71 para el Grupo 2. Según el OP, tuvimos OP pre de 20.71º para el Grupo 1 y 26.60º para el Grupo 2. La flexibilidad OP fue de 73.61% para el Grupo 1 y 56.54% para el Grupo 2 (p=0.047). La corrección OP fue de 73.47% para el Grupo 1 y 72.11% para el Grupo 2. El índice de Cincinnati de la OP fue de 1.09 y 1.49, respectivamente para los Grupos 1 y 2 (p=0.045). CONCLUSIONES: la instrumentación con tornillos pediculares mostró corrección de la escoliosis semejante a la fijación con Luque-Galveston y mayor poder de corrección de la oblicuidad pélvica en el tratamiento de las deformidades neuromusculares.<br>OBJETIVE: to compare the correction of the major curve and pelvic obliquity using Luque-Galveston instrumentation and pedicle screw constructs in the treatment of neuromuscular scoliosis. METHODS: seventy-four patients treated by fusion posterior to the sacrum were investigated using preoperative, traction and postoperative radiographs. Twenty-four cases were submitted to Luque-Galveston instrumentation (Group 1) and fifty were submitted to pedicle screw fixation (Group 2). Radiographic parameters were: major curve angle in the preoperative (Cobb preop), traction (Cobb traction), and postoperative films (Cobb postop), flexibility, final correction, and the Cincinnati Index, which correlates final correction and flexibility (Cincinnati = Correctioln / Flexibility). The same parameters were analyzed for pelvic obliquity (PO): PO preop, PO traction, PO postop, Flexibility PO, Correction PO, and Cincinnati Index for PO. RESULTS: mean age in the Group 1 was 12.24 years and 16.13 years in the Group 2 (p=0.001). The commonest disease in Group 1 was spinal muscular atrophy (38%) and in Group 2, cerebral palsy (62%). The mean major curve angle was 76.67º in Group 1 and 85.54º in Group 2. Flexibility was 45.32% in Group 1 and 39.47% in Group 2. Postoperative correction was 63.07% in Group 1 and 59.8% in Group 2. Cincinnati Index was 1.44 in the Group 1 and 1.77 in the Group 2. Mean PO preop was 20.71º in Group 1 and 26.60º in Group 2. PO Flexibility was 73.61% in Group 1 and 56.54% in Group 2 (p=0.047). PO Correction was 73.47% in Group 1 and 72.11% in Group 2. Cincinnati Index for PO was 1.09 in Group 1 and 1.49 in Group 2 (p=0.045). CONCLUSIONS: postoperative major curve correction was similar with pedicle screws and Luque-Galveston instrumentation, but pelvic obliquity correction was greater when pedicle screw was used in the surgical treatment of neuromuscular scoliosis