Sagittal Alignment Concepts and Spinopelvic Parameters / Conceitos de alinhamento sagital e parâmetros espinopélvicos

Abstract Spinal surgery continues to expand its horizons to care for disabled patients presenting pain and deformities. Over the past decade, our knowledge of spinal alignment, from the skull to the pelvis, has increased considerably. Such knowledge must expand to reach general orthopedists and improve the care required for so many people. Global spinal alignment is a critical concept in understanding the impact of pathological conditions (degenerative diseases, traumas, deformities) and their treatment, including spinal instrumentation and arthrodesis. Therefore, the treatment of any spinal disease must include the knowledge of the complexity of the spinopelvic alignment. At first, all parameters seem like pure mathematics, hardly applicable to the everyday life of the inattentive reader. However, it gradually becomes clear that, like everything else in orthopedics, biomechanics is an essential part of the knowledge of the musculoskeletal system, revealing the logic behind the physiology of movements. The knowledge of the sagittal alignment concepts and spinopelvic parameteres provide a better comprehension of the axial and appendicular skeletons, increasing the understanding of the physiological and adaptive spinal processes in the face of the degenerative process that increases throughout life.

Resumo A cirurgia da coluna continua a expandir seus horizontes para cuidar dos pacientes incapacitados com dor e deformidades. Desde a última década, nosso conhecimento sobre o alinhamento espinal, do crânio à pelve, aumentou consideravelmente. Portanto, faz-se necessária a expansão de tal conhecimento para o ortopedista geral, para que possamos proporcionar melhores cuidados para essa população. O alinhamento espinal global é um conceito crítico no entendimento do impacto ocasionado pela condição patológica (doença degenerativa, trauma, deformidade) e mesmo do seu tratamento, como na instrumentação e artrodese da coluna. O tratamento de qualquer doença na coluna deve incluir o entendimento da complexidade do alinhamento espinopélvico. A princípio, todos os parâmetros parecem puramente matemáticos e pouco aplicáveis à realidade do leitor mais desatento. Mas, aos poucos, fica claro que, como tudo em ortopedia, a biomecânica faz parte essencial do conhecimento do sistema musculoesquelético, tornando mais claras as lógicas da fisiologia do movimento. O conhecimento dos conceitos de alinhamento sagital e dos parâmetros espinopélvicos proporcionam uma melhor compreensão dos esqueletos axial e apendicular, além de um melhor entendimento dos processos fisiológicos e adaptativos da coluna frente ao processo degenerativo crescente que ocorre ao longo da vida.

Evaluation of the Radiographic Parameters of Sagittal and Spinopelvic Alignment in Patients with Osteoarthritis submitted to Total Hip Arthroplasty / Avaliação dos parâmetros radiográficos do alinhamento sagital e espinopélvico em pacientes com osteoartrite submetidos à artroplastia total do quadril

Abstract Objective To evaluate radiographic parameters of sagittal and spinopelvic alignment in patients with hip osteoarthritis (OA) undergoing primary total hip arthroplasty (THA) to define the primary surgical approach in individuals with concomitant spinal and hip joint disease. Methods Longitudinal, prospective, comparative study with 27 patients undergoing THA and 43 subjects without OA. Results An association between hip and spine degenerative disease in patients with OA was noted. After THA, radiographic parameters of pelvic tilt angle, sagittal vertical axis (EVS) and seventh cervical vertebra/sacrofemoral distance (C7/DSF) ratio were similar to values from volunteers without joint disease. Global coronal alignment (ACG), sagittal alignment, spinopelvic T1 and T9 tilts (IT1EP and IT9EP), sacral tilt (IS), pelvic version (VP), pelvic type and lumbopelvic complex (CLP) did not change after THA. Conclusion Among the sagittal and spinopelvic alignment parameters evaluated, the pelvic tilt angle, the EVS, and the C7/DSF ratio were corrected after THA and can guide the surgeon in the decision-making process for patients with concomitant spinal and hip joint disease. Spinal deformity may compensate for hip changes.

Resumo Objetivo Avaliar os parâmetros radiográficos do alinhamento sagital e espinopélvico de pacientes com osteoartrite (OA) de quadril submetidos à artroplastia total de quadril (ATQ) primária, com o intuito de definir a abordagem cirúrgica primária em pacientes com doença concomitante na coluna vertebral e na articulação do quadril. Métodos Estudo longitudinal, prospectivo, comparativo, envolvendo 27 pacientes submetidos à ATQ e 43 indivíduos sem OA. Resultados Foi observada associação entre doença degenerativa no quadril e na coluna nos pacientes com OA. Após a ATQ, os parâmetros radiográficos do ângulo da báscula da bacia, do eixo vertical sagital (EVS) e da razão de C7/DSF (sétima vértebra cervical/distância sacrofemoral) foram semelhantes aos valores dos voluntários sem doença articular. O alinhamento coronal global (ACG), o alinhamento sagital, as inclinações T1 e T9 espinopélvicas (IT1EP e IT9EP), a inclinação sacral (IS), a versão pélvica (VP), e o tipo de pelve e do complexo lombopélvico (CLP) não sofreram alteração depois da ATQ. Conclusão Dentre os parâmetros do alinhamento sagital e espinopélvico avaliados, o ângulo da báscula da bacia, o EVS e a razão C7/DSF foram corrigidos após a ATQ e podem orientar o cirurgião na tomada de decisão para pacientes com doença concomitante na coluna vertebral e na articulação do quadril. A deformidade da coluna pode ser compensatória às alterações do quadril.

Effect of posterior osteotomy on the sagittal parameters of the spinopelvis in patients with lumbar degenerative kyphosis / 中国骨伤

OBJECTIVE@#To investigate the influence of posterior osteotomy on spinopelvic parameters in lumbar degenerative kyphosis (LDK) patients.@*METHODS@#The clinical data of 21 patients with lumbar degenerative kyphosis who underwent osteotomy from January 2012 to December 2015 were retrospectively analyzed. There were 5 males and 16 females, aged from 55 to 76 years with an average of (66.24±5.13) years. All patients had taken preoperative and postoperative full length spinal X-ray, analyzing the spinopelvic parameters as thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS).@*RESULTS@#All operations were successful, the average operative time was 190 min (160 to 220 min) and intraoperative blood loss was 1 000 ml (800 to 1900 ml). Parameters of the patients between preoperative and period 1-year follow-up were as follows : preoperative TK increased from (31.67±21.13) ° to (34.67±11.60) °, LL corrected from (4.76±3.17) ° to (37.41±6.28) °, PT reduced from (33.94±5.01) ° to (20.12±5.36) °, and SS improved from (18.47±2.60) ° to (31.71±4.30) °, SVA restored from (13.24±3.60) cm to (2.82±1.33) cm. There were significant differences of spinopelvic parameters between preoperation and postoperation (<0.05).@*CONCLUSION@#Posterior osteotomy can effectively reconstruct the sagittal balance of spinopelvis in patients with lumbar degenerative kyphosis. The recovery of lumbar lordosis and sacral slope is closely related to the reconstruction of sagittal balance.

Analysis of spinopelvic sagittal parameters in degenerative lumbar spondylolisthesis / 第二军医大学学报

Objective To explore the characteristics of spinopelvic sagittal parameters in degenerative lumbar spondylolisthesis patients and the relationship between these parameters and lumbar spondylolisthesis. Methods From Jun. 2016 to Jun. 2018, 42 patients with degenerative lumbar spondylolisthesis (DLS) were enrolled in study group, and 58 degenerative lumbar disease patients without spondylolisthesis were enrolled in control group. The general characteristics of the patients were collected. The sagittal parameters, including pelvic tilt (PT), pelvic incidence (PI), sacral slope (SS), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), lumbar lordosis (LL) and sagittal vertical axis (SVA), were measured on lateral X-ray films of full-length spine. The differences of general characteristics and sagittal parameters were compared between the two groups. With the lumbar spondylolisthesis rate as dependent variable and the spinopelvic sagittal parameter as independent variable, logistic regression model was used to analyze the risk factors of lumbar spondylolisthesis. Results There were no significant differences in the age, gender, height or body mass of the patients between the two groups (all P>0.05). There were significant differences in the PT, PI, SS, LL, TLK and SVA between the DLS group and the control group (all P0.05). Logistic regression analysis showed that LL and PT were risk factors of lumbar spondylolisthesis (both P<0.05). Conclusion The sagittal parameters (PT, PI, SS, LL, TLK and SVA) in the patients with DLS are significantly changed. LL and PT are the risk factors of lumbar spondylolisthesis.

Correlation between spinopelvic sagittal parameters and adjacent segment disease after lumbar fusion / 第二军医大学学报

Objective To analyze the correlation between adjacent segment disease (ASDis) after lumbar fusion and spinopelvic sagittal parameters, and to explore the risk factors. Methods From Jan. 2013 to Oct. 2017, the patients undergoing revision surgery for ASDis after lumbar fusion in Changhai Hospital of Naval Medical University (Second Military Medical University) were enrolled as ASDis group, and the patients who did not have ASDis after lumbar fusion during the same follow-up period were taken as controls. The clinical data of the patients in the two groups were retrospectively analyzed. The differences of the general data (age, gender, body mass index [BMI], follow-up time and the etiology of the first operation) and the spinopelvic sagittal parameters (thoracic kyphosis [TK], sagittal vertical axis [SVA], lumbar lordosis [LL], segmental lumbar lordosis [sLL], pelvic incidence [PI], pelvic tilt [PT] and sacral slope [SS]) were compared between the two groups. Results There were 25 patients in the ASDis group and 50 patients in the control group. There were no significant differences in the age, gender, BMI, follow-up time or the etiology of the first operation between the two groups (all P>0.05). Compared with the control group, the LL, sLL and SS were significantly lower in the ASDis group (36.00°±5.44°vs 43.88°±10.62°, 17.80°±5.79°vs 27.62°±6.74°, 27.50°±5.30°vs 31.06°±7.48° all P0.05). Meantime, the proportion of patients with SVA>50 mm, the difference of PT and LL (PT-LL)=10°, and the ratio of sLL to LL (RL)<60% were significantly higher in the ASDis group than those in the control group (18/25 vs 21/50, 16/25 vs 11/50, 21/25 vs 17/50; all P<0.05). Conclusion The sagittal imbalance after lumbar fusion is closely associated with ASDis, and compensatory kyphosis of adjacent lumbar segments due to surgical segmental lordosis may be one of the causes of ASDis after lumbar fusion.

Comparison of the Effects of Magnetically Controlled Growing Rod and Tradiotinal Growing Rod Techniques on the Sagittal Plane in the Treatment of Early-Onset Scoliosis

OBJECTIVE: Comparing the effects of magnetically controlled growing rod (MCGR) and traditional growing rod (TGR) techniques on the sagittal plane in the treatment of early-onset scoliosis (EOS).METHODS: Twelve patients were operated using dual MCGR technique in one center, while 15 patients were operated using dual TGR technique for EOS in another center. Patients’ demographic characteristics, complications and radiological measurements such as cobb angle, thoracic kyphosis, lumbar lordosis, T1–S1 range (mm), proximal junctional angle, distal junctional angle, sagittal balance, coronal balance, pelvic incidence, sacral slope and pelvic tilt were assessed and compared in preoperative, postoperative and last follow-up period.RESULTS: Age and sex distributions were similar in both groups. The mean number of lengthening in the MCGR group was 12 (8–15) and 4.8 (3–7) in the TGR group. Two techniques were shown to be effective in controlling the curvature and in the increase of T1–S1 distance. In TGR group, four patients had rod fractures, six patients had screw pull-out and four patients had an infection, whereas three patients had screw pull-out and one patient had infection complications in the MCGR group.CONCLUSION: There was no significant difference between the two groups in terms of cobb angle, coronal and sagittal balance and sagittal pelvic parameters. MCGR can cause hypokyphosis and proximal junctional kyphosis in a minimum 2-year follow-up period. The implant-related complications were less in the MCGR group. However, larger case groups and longer follow-up periods are required for the better understanding of the superiority of one method on other in terms of complications.

Comparison of the Effects of Magnetically Controlled Growing Rod and Tradiotinal Growing Rod Techniques on the Sagittal Plane in the Treatment of Early-Onset Scoliosis

OBJECTIVE: Comparing the effects of magnetically controlled growing rod (MCGR) and traditional growing rod (TGR) techniques on the sagittal plane in the treatment of early-onset scoliosis (EOS). METHODS: Twelve patients were operated using dual MCGR technique in one center, while 15 patients were operated using dual TGR technique for EOS in another center. Patients’ demographic characteristics, complications and radiological measurements such as cobb angle, thoracic kyphosis, lumbar lordosis, T1–S1 range (mm), proximal junctional angle, distal junctional angle, sagittal balance, coronal balance, pelvic incidence, sacral slope and pelvic tilt were assessed and compared in preoperative, postoperative and last follow-up period. RESULTS: Age and sex distributions were similar in both groups. The mean number of lengthening in the MCGR group was 12 (8–15) and 4.8 (3–7) in the TGR group. Two techniques were shown to be effective in controlling the curvature and in the increase of T1–S1 distance. In TGR group, four patients had rod fractures, six patients had screw pull-out and four patients had an infection, whereas three patients had screw pull-out and one patient had infection complications in the MCGR group. CONCLUSION: There was no significant difference between the two groups in terms of cobb angle, coronal and sagittal balance and sagittal pelvic parameters. MCGR can cause hypokyphosis and proximal junctional kyphosis in a minimum 2-year follow-up period. The implant-related complications were less in the MCGR group. However, larger case groups and longer follow-up periods are required for the better understanding of the superiority of one method on other in terms of complications.

Prevention of Adjacent Segmental Disease after Fusion in Degenerative Spinal Disorder: Correlation between Segmental Lumbar Lordosis Ratio and Pelvic Incidence–Lumbar Lordosis Mismatch for a Minimum 5-Year Follow-up

STUDY DESIGN: Retrospective study. PURPOSE: Associations among risk factors related to adjacent segmental disease (ASD) remain unclear. We evaluated the risk factors and segmental lordosis ratio to prevent ASD developing after lumbar spinal fusion. OVERVIEW OF LITERATURE: Risk factors related to ASD development are age, sex, obesity, pre-existing degeneration, number of fusion segments, and decreased postoperative lumbar lordosis (LL). However, the associations among these factors are still unclear and should be clearly identified. METHODS: We retrospectively reviewed data on 274 patients who underwent lumbar spinal fusion of three segments or below for lumbar degenerative disease from January 2010 to December 2012, with over 5 years of follow-up. Patients with preoperative sagittal vertical axis (SVA) >5 cm were excluded due to sagittal imbalance. A total of 37 patients with ASD and 40 control patients (CTRL) were randomly selected in a similar distribution of matching variables: age, sex, and preoperative degenerative changes. Sex, age, number of fusion segments, radiologic measurements, L4–5–S1/L1–S1 LL ratio, and spinopelvic parameters (pelvic incidence [PI], pelvic tilt [PT], sacral slope [SS], and SVA) were analyzed. Logistic regression was used to analyze the correlation between PI–LL mismatch and L4–5–S1 segmental lordosis rate. RESULTS: No significant difference was found between ASDs and CTRL groups regarding age, sex, number of fusion segments, fusion method, and preoperative and postoperative spinopelvic parameters (PI, SS, PT, and LL). However, regarding the L4–5–S1/L1–S1 lordosis ratio, 50% (p=0.045), 60% (p=0.031), 70% (p=0.042), 80% (p=0.023), and 90% (p=0.023) were statistically significant; 10 group, and the difference was statistically significant (p=0.048). CONCLUSIONS: Patients with a postoperative L4–5–S1/L1–S1 lordosis ratio >50% had less occurrence of ASD. Correcting LL according to PI and physiologic segmental lordosis ratio is important in preventing ASD.

Influence of Distal Fusion Level on Sagittal Spinopelvic and Spinal Parameters in the Surgical Management of Adolescent Idiopathic Scoliosis

STUDY DESIGN: Retrospective analysis of adolescent idiopathic scoliosis. PURPOSE: This study aimed to investigate the influence of distinct distal fusion levels on spinopelvic parameters in patients with adolescent idiopathic scoliosis (AIS) who underwent posterior instrumentation and fusion surgery. OVERVIEW OF LITERATURE: The distal fusion level selection in treatment of AIS is the one of milestone to effect on surgical outcome. Most of the paper focused on the coronal deformity correction and balance. The literature have lack of knowledge about spinopelvic changing after surgical treatment and the relation with distal fusion level. We evaluate the spinopelvic and pelvic parameter alteration after fusion surgery in treatment of AIS. METHODS: A total of 100 patients with AIS (88 females and 12 males) were retrospectively reviewed. Patients were assigned into the following three groups according to the distal fusion level: lumbar 2 (L2), lumbar 3 (L3), and lumbar 4 (L4). Using a lateral plane radiograph of the whole spine, spinopelvic angular parameters such as thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT) were radiologically assessed. RESULTS: The mean age was 15±2.4 years, and the mean follow-up period was 24.27±11.69 months. Regarding the lowest instrumented vertebra, patients were categorized as follows: 30 patients in L2 (group 1), 40 patients in L3 (group 2), and 30 patients in L4 (group 3). TK decreased from 36.60±13.30 degrees preoperatively to 26.00±7.3 degrees postoperatively in each group (p=0.001). LL decreased from 52.8±9.4 degrees preoperatively to 44.30±7.50 degrees postoperatively (p=0.001). Although PI showed no difference preoperatively among the groups, it was statistically higher postoperatively in group 3 than in the other groups (p 0.05). However, mean SS was significantly higher in group 3 (p=0.042, p < 0.05). PT decreased from 15.50±7.90 degrees preoperatively to 15.2±7.10 degrees postoperatively. The positive relationship (28.5%) between LL and PI measurements was statistically significant (r=0.285; p=0.004, p < 0.01). Furthermore, the positive relationship (36.5%) between LL and SS measurements was statistically significant (r=0.365; p=0.001, p < 0.01). CONCLUSIONS: When the distal instrumentation level in AIS surgery is below L3, a significant change in PT and SS (pelvic parameters) is anticipated.

Posterior-Only Approach with Pedicle Screws for the Correction of Scheuermann's Kyphosis

STUDY DESIGN: Retrospective study (level of evidence: level 3). PURPOSE: The purpose of this study was to evaluate the clinical and radiological results of the posterior-only approach with pedicle screws for the treatment of Scheuermann's kyphosis (SK). OVERVIEW OF LITERATURE: The correction of SK with instrumentation can be performed using posterior-only or combined anterior-posterior procedures. With the use of all-pedicle screw constructs in spine surgery, the posterior-only approach has become a popular option for the definitive treatment of SK. In a nationwide study involving 2,796 patients, a trend toward posterior-only fusion with lower complication rates was reported. METHODS: We retrospectively reviewed the data of patients who underwent posterior-only correction for SK between January 2005 and May 2013. Patients with a definite diagnosis of SK who fulfilled the minimum follow-up criterion of 24 months were included. The thoracic kyphosis (T5–T12), lumbar lordosis (L1–S1), and thoracolumbar junction (T10–L2) angles were measured from preoperative, postoperative, and last control radiographs. Sagittal balance, thoracic length, thoracic diameter, Voutsinas index and the sacral slope, pelvic tilt, proximal junction kyphosis, and distal junction kyphosis angles were also measured. RESULTS: Forty-five patients underwent surgery for the treatment of SK between 2005 and 2013. After applying the exclusion criteria, 20 patients (18 males and 2 females) with a mean age of 19 years were included. The mean thoracic kyphosis angle was 79.8 degrees preoperatively, 44.6 degrees postoperatively, and 44.9 degrees at the last control. There were statistically significant differences between preoperative and postoperative values in the thoracic kyphosis and lumbar lordosis angles, thoracic length, thoracic diameter, and Voutsinas index (p<0.05). CONCLUSIONS: The clinical and radiological results of the current study suggest that posterior-only fusion is an efficient technique for the treatment of SK.

Correlates of Bone Mineral Density and Sagittal Spinal Balance in the Aged

OBJECTIVE: To investigate the relationship between bone mineral density (BMD) and sagittal spinal balance in the Korean elderly population. METHODS: The retrospective study included subjects aged 60 years and above, who had whole-spine lateral radiography and dual-energy X-ray absorptiometry (DEXA) within a year's gap between each other. Sagittal vertical axis (SVA) for evaluation of sagittal spinal balance and five spinopelvic parameters were measured through radiography. The presence of compression fracture was identified. Correlations of BMD T-scores with SVA and with the spinopelvic parameters were assessed using Pearson correlation coefficient (PCC). Linear regression analyses were performed between SVA and the clinical and radiologic variables. RESULTS: One hundred twenty-two subjects (42 males and 80 females; mean age, 69.93+/-5.5 years) were included in the study. BMD, femur or spine, was not correlated with SVA or any spinopelvic parameters in both genders (PCC<+/-0.2), except that spine BMD in men was associated with sacral slope. Univariate regression analysis revealed association between SVA and lumbar lordosis, pelvic tilt, and compression fractures in both genders; it was also associated with age and pelvic incidence in females and with sacral slope in males. Multivariate linear regression model showed lumbar lordosis and compression fracture as variables affecting SVA in both sexes; pelvic incidence was another factor affecting SVA in women only. CONCLUSION: BMD was not associated with sagittal spinal balance in the aged. Sagittal spinal balance was explained partly by lumbar lordosis and compression fracture. Further study is warranted to understand progression of sagittal imbalance with age.