Global Spinal Balance Research Articles

Comparison of PLIF/TLIF and LLIF for two-level degenerative lumbar spondylolisthesis

IntroductionIn recent years, lateral lumbar interbody fusion (LLIF), performed as extreme lateral interbody fusion (XLIF) and oblique lateral interbody fusion (OLIF), has also become widely used for anterior-posterior corrective fusion. However, there are few detailed reports comparing techniques in the treatment of two-level degenerative spondylolisthesis. We compared the surgical invasiveness and postoperative outcomes between posterior interbody fusion with posterior lumbar interbody fusion (PLIF) or transforaminal lumbar interbody fusion (TLIF) and LLIF for two-level lumbar degenerative spondylolisthesis. MethodsFifteen patients underwent PLIF or TLIF at 2 vertebral intervals (posterior group) and 8 patients received XLIF or OLIF (LLIF group). The following parameters were examined: operative time, blood loss, preoperative %slip, preoperative sagittal parameters, postoperative %slip, postoperative 1-year %slip, postoperative 1-year sagittal parameters, bone fusion rate at 1 year postoperatively, pre- and postoperative visual analog scale scores, pre- and postoperative Japanese Orthopaedic Association (JOA) scores, and complications. ResultsIn the LLIF group, blood loss was significantly lower and operative time was shorter than in the posterior group. There were no significant differences for 1-year postoperative %slip, sagittal vertical axis, or lumbar lordosis, although the frequency of cases with a 1-year postoperative pelvic incidence (PI)-LL ≤ 10 degrees was significantly higher in the LLIF group. In both groups, JOA scores were improved significantly at 1 year postoperatively (both p < 0.01), with no remarkable difference in improvement rate between the groups (p = 0.09). ConclusionsLLIF was less invasive, comparably effective, and more preserving of global spinal balance in correcting two-level degenerative spondylolisthesis than conventional posterior interbody fusion.

A New Global Spinal Balance Classification Based on Individual Pelvic Anatomical Measurements in Patients With Adult Spinal Deformity.

A retrospective study. This study aims to establish a new, easy-to-implement global spinal balance (GSB) classification based on individual pelvic anatomical measurements in adult spinal deformity patients, and to validate this classification in terms of patients' quality of life (QOL). Coronal (central sacral vertical line) and sagittal (C7 sagittal vertical axis [C7 SVA]) lines are standard parameters to evaluate GSB. However, these parameters do not consider individual differences in height and physique. Therefore, a new classification to more simply evaluate GSB related to QOL would be a beneficial tool. This study included 279 patients with adult spinal deformity. The enrollment criteria included age >18 years and scoliosis >30°. GSB was evaluated based on C7 coronal vertical axis and C7 SVA, and was graded with our sagittal (Grades 1-3) and coronal classifications (Grades 1-3), where larger values represented worse GSB. In addition, total global balance classification (Grades 1-3) was also established based on both coronal and sagittal classifications. Patient self-assessment measures of health status were collected using the Scoliosis Research Society patient questionnaire (SRS-22). The relationships between responses to the SRS-22 and GSB were evaluated using partial correlation coefficients, adjusted by age. A newly described coronal classification correlated with the preoperative function (P < 0.02), pain (P = 0.001), subtotal (P < 0.001) domains in the SRS-22, whereas a newly described sagittal classification was correlated with the preoperative subtotal domain (P < 0.001). There were also significant correlations between total global balance and the preoperative function (P = 0.03) and subtotal domains (P < 0.001) in the SRS-22. We present a simple new classification for GSB that strongly correlates with QOL in patients with adult spinal deformity, thereby translating clinical data into meaningful patient outcomes and livelihoods.Level of Evidence: 4.

Can spinal deformity patients maintain proper arm positions while undergoing full-body X-ray?

The compliance rate of arm positioning during full-body X-rays varies depending on operative status (preoperative vs postoperative), age, and diagnosis. Retrospective cohort. Despite the importance of patients maintaining arms in the same position in preoperative and postoperative standing films, patients are known to have their arms in varying positions, confounding radiographic interpretation and making global sagittal and coronal spinal balance assessment variable and potentially less reliable. This study seeks to examine arm position compliance among adult and pediatric surgical spinal deformity patients undergoing total body X-rays over the course of 4years (2015-2018). A retrospective radiographic review was performed on 382 spinal deformity patients from July 2015 to July 2018. The study's dependent variable of interest was standardized arm position (fingers on the clavicles with shoulders in 45° of forward elevation while the patient is in a free-standing posture) observed during full-body X-rays obtained for spinal deformity evaluation. Deviations and compliance to the standard protocol for full-body X-ray arm positioning was recorded and analyzed across various independent factors, including year of surgery, pre- and postoperative periods, type of spine surgery, and patient age. Chi-square and Cochran-Armitage analyses were performed to study categorical and trends, respectively. The overall compliance rate for maintaining standardized arm position was 90% for all 370 patients (277 adult and 93 pediatric), in preoperative and postoperative setting. Adults were more likely to follow protocol than pediatric patients (92.9% vs. 82.4%, P value = 0.003). The postoperative setting observed a significantly lower overall compliance rate when compared to the preoperative period (67.8% vs. 87.0%, P value < 0.0001). Patients undergoing neuromuscular scoliosis (73.3%), vertebral column resection (VCR) (70%), and growing rod lengthening (GRL) (57.1%) had the lowest overall compliance rate in the preoperative setting. In the postoperative setting, patients with GRL, VCR, revision congenital scoliosis, congenital scoliosis, neuromuscular scoliosis, and pedicle subtraction osteotomy (PSO) surgeries were compliant less than or equal to 50% of the time. From 2015 to 2018, there was an overall statistically significant increase in compliance rate (61.1% to 90.6%). Over the study period, adult patients became significantly more compliant to protocol. This was not observed in the pediatric population. This study documented the patient compliance rate of maintaining standardized arm position during full-body X-rays of spinal deformity patients. The overall compliance rate was 90.0% for all patients in the preoperative and postoperative setting. Risk factors for lower compliance rates included patients that were pediatric, postoperative, neuromuscular, and those who underwent a complex vertebral osteotomy or GRL. There was a trend showing improved compliance rate throughout the 4-year study period, which highlights the importance of having an ancillary staff who is comfortable with a consistent standard of care protocol. These results should help other centers optimize arm positioning in their patients undergoing full-body X-rays in the future.

Long-term results of hemivertebra excision: How does the spine behave after the peak of puberty?

Early hemivertebra (HV) excision and posterior spinal fusion (PSF) is advocated as the treatment of choice in congenital kyphoscoliosis. We assessed global spinal balance and spinal deformity status once the pubertal peak has taken place, in children with a history of HV excision and PSF at age younger than 5years. Twenty-seven children with congenital kyphoscoliosis without co-existing proximal/distal congenital spinal abnormalities who underwent HV excision and PSF of ≤ 5 levels at age younger than 5years and who had reached the peak of puberty at the last follow-up visit were evaluated. Twenty-seven HV excision were performed. Mean age at surgery was 3years and 2months. A mean of 3.2 segments were fused. Imbalance of the trunk was observed in 80% of thoracic and 75% of thoracolumbar HV excision. No arthrodesis technique (4 cases) presented 100% of spine decompensation. All children younger than 2years at the time of surgery developed spinal imbalance. Eighteen patients (67%) had global spine imbalance; 81% male population and 63% of the female population. Mean age at surgery was 3years + 2months. Mean age of the patients at the time of the study was 15years + 5months. Mean follow-up was 12years + 3months. Many of these patients developed spinal imbalance and scoliosis worsened at the final follow-up. Early age at surgery, preoperative scoliosis severity, HV location, no arthrodesis technique, and the adding-on phenomenon may be involved.

Association of cervical sagittal alignment with adjacent segment degeneration and heterotopic ossification following cervical disc replacement with Prestige-LP disc.

Cervical sagittal balance plays important roles in transmitting the load of the head and maintaining global spinal balance. This study aimed to identify the association of cervical sagittal alignment with adjacent segment degeneration (ASD) and heterotopic ossification (HO) after Prestige-LP cervical disc replacement (CDR). We enrolled 132 patients who underwent one-level Prestige-LP CDR with 2-10 years of follow-up. Cervical sagittal alignment parameters, including the degree of C2-C7 lordosis (CL), functional spinal unit angle (FSUA), sagittal vertical axis (SVA),, and T1 slope (T1s), were measured. ASD and HO were evaluated at the last follow-up. Unpaired t tests and logistic regression analysis were used to identify the associations of cervical sagittal alignment with ASD and HO. We found that patients who developed ASD showed significantly lower FSUA (2.1° vs. -1.4°, p < 0.001) and T1s values (28.4° vs. 25.5°, p = 0.029) after surgery. Similarly, the postoperative CL was significantly better in patients without ASD or HO (18.0° vs. 14.4°, p = 0.043). The decrease in the T1s at the last follow-up was significantly larger in the patients with ASD (-11.0° vs. -3.2°, p = 0.003), HO (-6.7° vs. -2.7°, p = 0.050), and ASD or HO (-7.0° vs. -0.8°, p < 0.001) than in those without ASD or HO. Multivariate logistic regression analysis showed that both the FSUA and T1s are associated with ASD and that the degree of CL is associated with postoperative complications. The results imply that maintaining cervical sagittal alignment after Prestige-LP CDR is important.

Skip constructs in spinal muscular atrophy: outcomes of a novel approach for posterior spinal instrumentation and fusion.

Many children with spinal muscular atrophy (SMA) develop progressive spinal deformity, worsening already compromised pulmonary function and global spinal balance. Early results demonstrate that intrathecal administration of nusinersen, a recent FDA-approved drug, improves motor function and ventilator-free survival, necessitating preservation of intrathecal access when considering PSIF. The purpose of this study is to assess medium-term outcomes of a specialized approach for posterior spinal instrumentation and fusion (PSIF) to preserve intrathecal access in patients with SMA. A retrospective review of patients with SMA undergoing PSIF at a single tertiary academic medical center during a 3-year period was completed. To facilitate intrathecal drug administration, the traditional approach to PSIF was modified to "skip" one or more intervertebral levels at the thoracolumbar junction. Clinical notes and radiographs were reviewed for postoperative outcomes including major coronal curve correction and complications, including loss of correction, hardware failure and surgical revision. Eight patients were identified, with a mean age of 12.7 ± 1.6years and follow-up of 4years. These patients had a mean preoperative major coronal curve of 56.4°, with mean curve correction of 35.2°. At follow-up, no patients experienced rod breakage, loss of correction, or postoperative chronic pain. Only one patient required revision surgery due to bony overgrowth at the skipped level after three and a half years. Implementing the skip construct approach for PSIF in patients with SMA allows for scoliosis correction without compromising intrathecal drug delivery. Follow-up at 4years reveals no adverse clinical events, hardware failure or loss of correction. IV.

Frontal and sagittal imbalance in patients with adolescent idiopathic deformity.

The human spinal column underwent many significant changes over the 4.5 million years of our ancestral bipedalism. The main change, however, came with acquiring multiple curvatures in the sagittal plane. This alteration seems to have exposed a weakness in our body's keystone and made us susceptible to thus far unbeknown problems of the spine because it has been noted that idiopathic scoliosis has not been observed in other primates. Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine causing an imbalance of the trunk as it increases in magnitude. A scoliotic curve comprises three components, the coronal, sagittal, and axial so that each curve can affect the global balance of the body differently. Patients with significant scoliotic deformities often find themselves at a biomechanical disadvantage when it comes to energy expenditure and keeping an upright stance. The pioneers of scoliosis research recognized the need for describing and quantifying deformity to better understand it, so they first translated clinical measurements to radiographs and built from there. The development of concepts like defining a curve by its end vertebrae and measuring its magnitude, assessing global spinal balance, describing the stable zone, and pinpointing the stable vertebra all followed suit. The importance of sagittal balance and restoring sagittal parameters during treatment was emphasized. In a quest to bring order to chaos, some tried to classify various scoliotic curve types. These classifications helped steer treatment decisions but were found lacking in many aspects. So far, a widely accepted three-dimensional classification of scoliosis still does not exist. This review aims to provide the reader with an overview of the development of balance and imbalance concepts in scoliosis.

Impact of cervical range of motion on the global spinal alignment in ankylosing spondylitis patients with thoracolumbar kyphosis following pedicle subtraction osteotomy

BACKGROUND CONTEXTThe head's center of gravity (COG) plumb line (PL) and C7 PL could be simultaneously positioned over the pelvis in adult spinal deformity with normal cervical mobility. However, the position of the head in relation to the global spinal alignment has yet to be investigated in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis. PURPOSEThe objective of this study was to analyze the position of head in relation to the global spinal alignment in AS-related thoracolumbar kyphosis. STUDY DESIGN/SETTINGRetrospective single-center study. PATIENT SAMPLEAS patients who underwent lumbar pedicle subtraction osteotomy for thoracolumbar kyphosis from January 2010 to August 2016 were reviewed. Only patients with a visible ear canal on the preoperative, immediate postoperative, and final follow-up radiographs were included. OUTCOME MEASURESThe chin-brow angle, cervical range of motion (ROM), lumbar lordosis (LL), thoracolumbar angle, thoracic kyphosis (TK), L1 pelvic angle, pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), TK+LL+PI, PI-LL, maximal kyphosis (MK), deformity angular rate, T1 pelvic angle, T1 tilt, spinosacral angle, sagittal vertical axis (SVA) COG-C7, SVA COG-femoral head (FH), and SVA C7-S were evaluated. Data regarding the health-related quality of life, including the Oswestry disability index (ODI) and visual analogue scale (VAS)-back score, were also collected preoperatively, 2 years postoperatively, and at the latest follow-up. METHODSThe cohort was divided into patients with occiput-trunk (OT) concordance or with OT discordance according to the SVA COG-C7 ≤30 mm or >30 mm, respectively. There was no funding in this study and there are no conflict of interest-associated biases. RESULTSA total of 43 patients (36 males and 7 females) with a mean age of 34.2 years (range, 18–59 years) were identified. There were 17 patients accompanied with OT concordance and 26 patients with OT discordance preoperatively. The cervical ROM was significantly lower (24.0° vs 56.1°, p<.001) and SVA COG-C7 was significantly larger (71.7 mm vs 7.4 mm, p<.001) in patients with OT discordance. Furthermore, the PT was larger (41.0° vs 33.5°, p=.010) in patients with OT discordance. After surgery, the whole cohort showed an improvement in LL (−8.6° vs −52.8°, p<.001). Moreover, the CBVA (25.4° vs 1.3°, p<.001) and SVA COG-C7 (46.2 mm vs 21.6 mm, p<.001) were significantly decreased following lumbar PSO. There were 13 patients accompanied with OT discordance postoperatively, and the cervical ROM was still lower (22.5° vs 42.8°, p=.024) in these patients. Postoperative PT was larger (26.5° vs 20.1°, p=.033) in the patients with OT discordance. At the latest follow-up, there were 17 patients accompanied with OT discordance. In these 17 patients, the cervical ROM was significantly lower (21.0° vs 47.0°, p=.001) and PT was significantly higher (26.2° vs 19.2°, p=.012). The ODI and VAS-back scores demonstrated no significant differences between the two groups preoperatively, 2 years postoperatively, or at the latest follow-up. CONCLUSIONSOT discordance in AS-related thoracolumbar kyphosis could be caused by the reduced cervical ROM. To maintain global spinal balance, the pelvis rotated further backward in response to the larger SVA COG-C7. Moreover, the larger SVA COG-C7 could be decreased after the lumbar PSO. Although there were radiographic differences between the patients with OT concordance and with OT discordance, there was no difference in clinical outcomes, and that a larger sample size and longer follow-up are needed.

The Large Individual Differences in the Range of Hip Joint Motion Rather Than Lumbar Spine Motion Affect Dynamic Spinopelvic Rhythm.

Introduction Global spinal balance and its relationship to the pelvis have received much attention, and various formulae have been used to predict postoperative spinopelvic alignment for spinal surgery. However, previous studies had limitations because no consideration was given to the dynamic factor. Methods Fifteen healthy adults without any lumbar disorder (group A) and 9 L4-spondylolisthesis patients (Group B) volunteered to participate in the study. Sequential images were captured with the subjects in the standing position with maximal forward bending followed by backward bending using a dynamic flat panel detector system. Spinopelvic parameters (LL: lumbar lordosis, SA: sacrofemoral angle, SS: sacral slope, PI: pelvic incidence, DP: distance of the horizontal movement of the pelvis) were evaluated. We also investigated the relationship between LL and SA (lumbar/hip [L/H] ratio) as the spinopelvic rhythm. Results In group A, the mean change in LL was 83.2 ± 9.5°; change in SA, 45.4 ± 16.6°; SS, 42.6 ± 8.9°; PI, 43.2 ± 7.7°; DP, 15.7 ± 3.4 cm, and L/H ratio, 3.6 ± 2.7. However, spinopelvic rhythm changed over time, because the change in LL was larger than the change in SA from the middle of the rising motion to the upright position. In group B, the mean change in LL was 50.3 ± 8.0°; SA, 56.9 ± 16.0°; SS, 27.5 ± 13.5°; PI, 47.4 ± 10.4°; DP, 12.7 ± 6.8 cm; and L/H ratio, 1.0 ± 0.5. Conclusions When compared with the change in LL, individual differences were largely noted in the change in SA. These results demonstrated that the range of hip joint motion under physiological conditions, unlike anatomical motion, differed substantially between individuals. Therefore, spinopelvic rhythm is dependent on the change in SA.

Effect of three-dimensional rotational deformity correction in surgery for adult degenerative scoliosis using lumbar lateral interbody fusion and posterior pedicle screw fixation.

Introduction Corrective surgery for adult degenerative scoliosis using lateral interbody fusion (LIF) and additional posterior fixation is an efficient procedure. However, it is unclear how this procedure affects rotational deformity correction. Therefore, the goal of the present study was to use three-dimensional (3D) images, taken during surgery, to investigate rotational deformity correction in the treatment of adult degenerative scoliosis using LIF and posterior fixation using a pedicle screw system. Methods The subjects were 12 females who were treated using LIF and posterior fixation for adult degenerative scoliosis. The patients had a mean age of 72 (65-76) years. 3D images were acquired before surgery, after LIF, and after additional posterior fixation. Rotational angles of the upper vertebra with respect to the lower vertebra of each fixed segment were measured in 3 planes. Correction factors for rotational deformity were investigated after LIF and additional posterior fixation. Results There were significant improvements in radiographical parameters for global spinal balance. The correction angles per segment were 4.7° for lateral bending, 6.9° for lordosis, and 4.5° for axial rotation. LIF was responsible for correction of four-fifths of lateral bending and axial rotation, and two-thirds of lordotic changes. Conclusions Lateral bending, axial rotational deformities, and lordosis were primarily corrected by LIF. Further lordosis correction was achieved using additional posterior fixation. These results indicate that corrective surgery for adult degenerative scoliosis using these procedures is effective for rotational deformity correction and leads to an ideal global spinal alignment.

Preventing Fusion Mass Shift Avoids Postoperative Distal Curve Adding-on in Adolescent Idiopathic Scoliosis.

Surgery for adolescent idiopathic scoliosis (AIS) is only complete after achievingfusion to maintain the correction obtained intraoperatively. The instrumented or fused segments can be referred to as the "fusion mass". In patients with AIS, the ideal fusion mass strategy has been established based on fulcrum-bending radiographs for main thoracic curves. Ideally, the fusion mass should achieve parallel endplates of the upper and lower instrumented vertebra and correct any "shift" for truncal balance. Distal adding-on is an important element to consider in AIS surgery. This phenomenon represents a progressive increase in the number of vertebrae included distally in the primary curvature and it should be avoided as it is associated with unsatisfactory cosmesis and an increased risk of revision surgery. However, it remains unknown whether any fusion mass shift, or shift in the fusion mass or instrumented segments, affects global spinal balance and distal adding-on after curve correction surgery in patients with AIS. (1) To investigate the relationship among postoperative fusion mass shift, global balance, and distal adding-on phenomenon in patients with AIS; and (2) to identify a cutoff value of fusion mass shift that will lead to distal adding-on. This was a retrospective study of patients with AIS from a single institution. Between 2006 and 2011 we performed 69 selective thoracic fusions for patients with main thoracic AIS. All patients were evaluated preoperatively and at 2 years postoperatively. The Cobb angle between the cranial and caudal endplates of the fusion mass and the coronal shift between them, which was defined as "fusion mass shift", were measured. Patients with a fusion mass Cobb angle greater than 20° were excluded to specifically determine the effect of fusion mass shift on distal adding-on phenomenon. Fusion mass shift was empirically set as 20 mm for analysis. Therefore, of the 69 patients who underwent selective thoracic fusion, only 52 with a fusion mass Cobb angle of 20° or less were recruited for study. We defined patients with a fusion mass shift of 20 mm or less as the balanced group and those with a fusion mass shift greater than 20 mm as the unbalanced group. A receiver operating characteristic (ROC) curve was used to determine the cutoff point of fusion mass shift for adding-on. Of the 52 patients studied, fusion mass shift (> 20 mm) was noted in 11 (21%), and six of those patients had distal adding-on at final followup. Although global spinal balance did not differ significantly between patients with or without fusion mass shift, the occurrence of adding-on phenomenon was significantly higher in the unbalanced group (55% (six of 11 patients), odds ratio [OR], 8.6; 95% CI, 2-39; p < 0.002) than the balanced group (12% [five of 41 patients]). Based on the ROC curve analysis, a fusion mass shift more than 18 mm was observed as the cutoff point for distal adding-on phenomenon (area under the curve, 0.70; 95% CI, 0.5-0.9; likelihood ratio, 5.0; sensitivity, 0.64; specificity, 0.73; positive predictive value, 39% [seven of 18 patients]; negative predictive value, 88% [30 of 34 patients]; OR, 4.8; 95% CI, 1-20; p = 0.02). Our study illustrates the substantial utility of the fulcrum-bending radiograph in determining fusion levels that can avoid fusion mass shift; thereby, underlining its importance in designing personalized surgical strategies for patients with scoliosis. Preoperatively, determining fusion levels by fulcrum-bending radiographs to avoid residual fusion mass shift is imperative. Intraoperatively, any fusion mass shift should be corrected to avoid distal adding-on, reoperation, and elevated healthcare costs. Level II, prognostic study.

Validation study of arm positions for evaluation of global spinal balance in EOS imaging.

The sagittal vertical axis (SVA) is important in the evaluation of spinal sagittal balance. Although the "fists-on-clavicles" (FOC) position has been widely used in radiographic examinations, it does not define shoulder flexion in detail. Meanwhile, in EOS imaging, the "hands-on-cheeks" (HOC) position is widely used but has not been well investigated. The purpose of this study was to investigate the relative usefulness of FOC and HOC in investigating SVA. Mean SVA was measured by EOS imaging using standing lateral radiographs of 34 volunteers in four different positions: relaxed (RLX), shoulder flexion at 90° with FOC (FOC90), elbows touching the trunk with FOC (FOCET), and HOC. The mean SVA was 2.0±2.1cm in RLX; -1.4±3.2cm in FOC90; -0.5±3.0cm in FOCET; and -0.2±2.9cm in HOC. The negative shift from RLX was significantly greater in FOC90 than in FOCET (-3.4±2.2 vs -2.5±2.4cm; p=0.0182). The negative shift from RLX in HOC was almost equal to that in FOCET; the difference was 0.3cm (-2.2±2.2 vs -2.5±2.4cm; p=0.2560). FOC90 showed a negative SVA shift in comparison with FOCET. The difference in the mean SVA between HOC and FOCET was 0.3cm, a clinically small difference.

Analysis of Normal Values of Sagittal Spinopelvic Radiographic Parameters in Indian Population

Introduction Ever since Legaye et al. in 1998 first described the importance of pelvic incidence as an important determinant of sagittal spinal balance, several other radiographic spinopelvic parameters have been defined. There are an increasing number of reports and studies from around the world signifying the role of these parameters in the maintenance of global spinal balance. Alteration in the normal values of the spinopelvic parameters has been implicated in causing accelerated degeneration, low back pain and even sagittal plane deformities. The recent literature has suggested that the best functional outcomes after any spinal surgery were achieved when these parameters have been normalized. In this setting, it is extremely important to know the normal values of these parameters in the target population. Though these values have been well quantified in the Caucasian population, there is a dearth of information in other racial groups. A few studies done in other population groups have shown some ethnic differences in the normal values of these parameters. Thus in our study we aim to quantify the normal values of sagittal spinopelvic radiographic parameters in Indian population. Materials and Methods The study was approved by our institute review board and the ethical committee. A total of 75 young, healthy and asymptomatic volunteers were enrolled into the study after taking a formal consent. There were 21 male and 54 female volunteers. Lateral sagittal digital radiographs of the whole spine including the base of skull up to the proximal ⅓ thigh were taken in standing position (patient is naturally standing up, looking horizontally, hands resting on a vertical support, upper limbs relaxed and elbows half bent). All the subjects were at a specific distance from the radiographic source and a single shot of X-rays have been used centering around D12. The parameters measured were pelvic incidence PI, pelvic tilt PT, sacral slope SS, thoracic kyphosis TK, lumbar lordosis LL, lordotic and kyphotic vertebra. All measurements were performed by two independent observers using the Surgimap spine software version 2.1.2. The values thus obtained were compared with the values described in other population groups. Results The mean values obtained in our population group were PI-47.85, PT-13.03, SS-34.8, LL-54.68, TK-24.03. A significant correlation was found between SS-LL (r-0.817), PI-SS(R-0.813), PI-LL(r-0.692), PI-PT(r-0.589), LL-TK (r-0.505). Comparing our data with European data, the pelvic incidence of our study was lower. We also found that the values of spinopelvic parameters did not vary much between males and females except PT, which was found to have a statistically significant difference between sexes ( p = 0.019). Conclusion The study demonstrated that pelvic incidence of the Asian population varied when compared with that of the Caucasian population. The pelvic incidence of our present study was similar to Japanese and Korean population. It was lower than that of the Caucasian population.

The effect of total hip arthroplasty on sagittal spinal-pelvic-leg alignment and low back pain in patients with severe hip osteoarthritis.

Sagittal spinopelvic malalignment has been reported in spinal disorders such as low back pain (LBP), and restoration of normal alignment is targeted when treating these disorders. Abnormal sagittal spinal-pelvic-leg alignment has been reported in patients with severe hip osteoarthritis (OA), who have a high prevalence of associated LBP. This prospective longitudinal study aimed to investigate changes in sagittal spinal-pelvic-leg alignment after total hip arthroplasty (THA) in patients with severe hip OA, and whether these changes contribute to LBP relief. Patients undergoing primary THA due to severe unilateral hip OA were recruited. Physical examination and X-ray films were taken to rule out any spinal disorder. Sagittal alignment of pelvis, hip, and spine was analyzed on lateral radiographs taken before (baseline) and 1year after (follow-up) THA. Functional instruments were completed by patients including: visual analog scale (VAS) for LBP, Roland-Morris Disability Questionnaire (RMDQ), and Harris Hip Score (HHS). Comparisons were carried out at baseline and follow-up, and between patients with and without LBP. The recruited 69 patients showed significantly reduced hip flexion and improved global spinal balance at follow-up compared with baseline. LBP was reported by 39 patients (56.5%) before surgery; at follow-up, 17 reported complete resolution, while 22 reported significant relief. Significant decreases in VAS and RMDQ scores in lumbar spine and increase in hip HHS were observed. THA in patients with severe hip OA could help correct abnormal sagittal spinal-pelvic-leg alignment and relieve comorbid LBP. Improvements in hip flexion and global spinal balance might be involved in the mechanism of LBP relief.

Sagittal balance of the spine in patients with osteoporotic vertebral fractures.

This study aims to compare the sagittal global spinal balance of patients consulting for osteoporosis, aged above 50years with and without osteoporotic vertebral fractures (VFs). Global spinal balance is abnormal even in subjects without VFs. VFs and age are determinants of sagittal global balance; however, pelvic parameters play a role in compensatory mechanisms. This study aims to compare the spine curvatures, pelvic parameters, and the sagittal global spinal balance of patients aged above 50years with and without osteoporotic vertebral fractures. Two hundred patients (95% women) aged 68.3 ± 9.5years underwent full skeleton radiographs in the standing position, by EOS®, a low dose biplane X-ray imaging system. VFs were evaluated according to Genant's classification. Spinal (thoracic and lumbar Cobb's indices, thoracic and lumbar tilts) and pelvic (pelvic tilt, sacral slope, and pelvic incidence) parameters were measured. Sagittal spinal balance was measured using the C7 plumb line and the spinosacral angle (SSA). We compared these parameters in patients with and without vertebral fracture and assessed the determinants of abnormal sagittal spinal balance. Sixty-nine patients had at least one VF. The sagittal spinal balance was significantly altered in patients with at least one VF, and there was an effect of the number and severity of VFs on parameters. Discriminative value for identification of patients with at least one VF, assessed by Area Under the Curves (AUCs) was 0.652 and 0.706 for C7 plumbline and SSA, respectively. Using multivariate analysis, parameters significantly associated with abnormal spinal balance (SSA) were the presence of at least one VF (OR = 4.96, P < 0.0001), age (OR = 1.07, P = 0.0006), and high pelvic incidence as a protective factor (OR = 0.93, P < 0.0001). Global spinal balance is abnormal in subjects consulting for osteoporosis, even in subjects without VFs. VFs and age are determinants of abnormal sagittal global balance; however, pelvic parameters play a role in compensatory mechanisms.

Pelvic parameters and global spine balance for spine degenerative disease: the importance of containing for the well being of content.

Spinal deformities and pathologies of the spinopelvic junction are conditions affecting up to 60-70% of the general aging population. In this review, we discuss the more recent knowledge on sagittal balance and its clinical implications. Review of the literature regarding global spine balance. Global spinal balance and its relationship to the pelvis correlate closely with disability and quality of life. It has been demonstrated that extensive surgery, previously considered to have poor balance between risks and outcomes, causes great improvements in health-related quality of life in the oldest age groups. Failure to restore normal sagittal alignment in patients primarily operated for other than deformity results in unacceptable rates of poor results and revision surgery.

Craniopelvic alignment in elderly asymptomatic individuals: analysis of 671 cranial centers of gravity.

Prospective radiographical analysis using the cranial center of gravity (CCG) of sagittal vertical axis (SVA) in elderly asymptomatic individuals. To determine sex differences and age-related correlations of CCG and relationships between CCG and other spinopelvic parameters/health-related quality of life (HRQOL) measures. Few studies have investigated CCG in a relatively large sample of elderly asymptomatic individuals. Six hundred seventy-one healthy participants older than 50 years (mean age, 72.9 yr; range, 50-92 yr) were enrolled. Whole-spine standing radiographs were obtained. The following radiographical measurements were obtained: (1) CCG-C7 SVA, (2) C7-SVA, (3) CCG-SVA, (4) C2-C7 lordosis angle, (5) thoracic kyphosis, (6) lumbar lordosis, (7) pelvic incidence, and (8) sacral slope. HRQOL measures included the EuroQol-5D and Oswestry Disability Index. Pearson product-moment correlation coefficients were calculated between pairs of radiographical measures and HRQOL. Sex differences were observed in CCG-C7 SVA, CCG-SVA, C2-C7 Cobb angle, thoracic kyphosis, and pelvic incidence. Three SVA parameters (CCG-C7 SVA, C7-SVA, CCG-SVA) rapidly increased between seventh and ninth decades and were approximately 40, 80, and 120 mm, respectively, in the ninth decade. Age-related correlations were observed for all parameters without pelvic incidence, and the CCG measurement correlated the most with age. Furthermore, CCG-SVA correlated with other spinopelvic measurements and HRQOL. Age-related changes and sex difference in craniopelvic alignment were analyzed. Craniopelvic alignment became rapidly positive with age, particularly in the eighth decade. The CCG measurement correlated the most with age and may be a useful index marker of global spinal balance in decision making for surgical treatment of adult deformity involving cervical and thoracolumbar lesions. 4.

Answer to the Letter to the Editor of I. Berg et al. concerning “Adolescent idiopathic scoliosis treated with posteromedial translation: radiologic evaluation with a 3D low-dose system” by B. Ilharreborde, G. Sebag, W. Skalli and K. Mazda; Eur Spine J (2013) Apr 12 [doi:10.1007/s00586-013-2902-6

We thank I. Berg et al. for their interest in our article. We are aware that malocclusion features have been reported more frequently in AIS patients than in the control population, but although all our patients were seen by an experimented dentist before surgery in order to look for an infection site, we have not specifically studied their occlusal variables or their facial asymmetry. This topic might be of interest in the future and we completely agree that low-dose stereoradiography using EOS device represents a promising and very adapted tool to carry on such research projects. Since anteroposterior and lateral acquisitions of the skull are necessary to analyze the global spinal balance, future studies should focus on the development and validation of a 3D-specific model of the facial skeleton that could later be added in the reconstruction software and, therefore, be forwarded to the attending orthodontist.

Redefining Global Spinal Balance

Prospective radiographical analysis of cranial center of mass (CCOM), C2, and C7 plumb lines in young and elderly asymptomatic individuals. To establish a normal range for craniosagittal balance for both young and elderly asymptomatic individuals. Global sagittal balance must account for the position of the head in relation to the spine and pelvis. The C7 plumb line defines thoracolumbar sagittal balance and has been shown to have significant impact on patient outcomes. However, the C7 plumb line fails to take into consideration the position of the head in relation to the pelvis. A total of 100 asymptomatic 20- to 40-year-old patients and 100 asymptomatic 60- to 80-year-old patients were enrolled. Standing plain radiographs of 14 × 36 in were obtained. CCOM, C2, and C7 plumb lines were drawn and measured from the superoposterior endplate of S1. A total of 78 asymptomatic 20- to 40-year-old patients and 62 asymptomatic 60- to 80-year-old patients had adequate radiographs. The mean plumb line values in the 20- to 40-year-old patients and 60- to 80-year-old patients, respectively, were as follows; CCOM 9.0 mm (SD, 31.5 mm) and 41.2 mm (SD, 35.7 mm); C2 -2.7 mm (SD, 32.7 mm) and 32.1 mm (SD, 33.6 mm); and C7 -16.4 mm (SD, 31.5 mm) and 10.6 mm (SD, 27.8 mm). One-way analysis of variance and Student t tests confirmed that these mean plumb line values were significantly different between young and elderly patients (P < 0.001). The change at each level over time was highly correlated with the other levels (r > 0.97; P < 0.001) as did the degree of change between groups (r > 0.90, P < 0.001). Spinopelvic alignment in conjunction with CCOM has increased our understanding of spinal balance by including the head and may better represent true global spinal balance. CCOM is an easily measured parameter by using the nasion-inion technique.

Posterolateral versus circumferential instrumented fusion for monosegmental lumbar degenerative disc disease using an expandable cage.

Theoretically, 360° instrumented fusion has been considered to offer better radiological correction than PLF. Despite numerous publications, this correlation is still weak with several controversies in the relative literature. This prospective randomized study was designed to compare the radiological segmental results, complications and outcome of 360° instrumented fusion with the use of a single diagonal expandable PLIF device versus posterolateral pedicle screw fixation in monosegmental lumbar DDD and to show that the use of an novel expandable cage is associated with low PLIF-related complication rate compared to conventional cages reported previously. Prospective randomized controlled clinical and radiological study. Adults who suffered from monosegmental DDD were eligible for enrolment in this trial. We randomly assigned 150 patients to receive either 360° instrumented fusion (group A) with expandable cage or PLF (group B). Differences between the two groups regarding clinical parameters and radiographic sagittal measurements after 36months of follow-up. The record included global [T12-S1 lordosis, sagittal global spinal balance (SB) (C7-mid-femoral axis)] and segmental [segmental disc wedging (SDW), anterior (ADHr) and posterior (PDHr) disc height ratio] radiological measurements at the instrumented segment. Additionally, clinical outcome was evaluated with VAS, SF-36 (Physical function and Bodily Pain) and ODI questionnaires. Fusion was evaluated with the use of Christiansen method. In 73 and 72 participants of group A and B, respectively, who completed follow-up to 36months, there were no differences with respect to the rate of improvement in SF-36, ODI and VAS scores. However, in the spines of group A, there was a significant increase in anterior disc height ratio (P=0.0057), posterior disc height (P=0.016) and segmental disc wedging (P=0.00021) without subsequent loss of correction. Fusion rate was radiologically shown in 94.5% and 87% spines of group A and B, respectively (P>0.2). Four and 9 spines in group A and B, respectively, showed non-union at the final observation. Our findings suggest that 360° fusion offers better sagittal radiological restoration associated with circumferential fusion. However, this difference seemed not to have any medium-term clinical impact. The use of expandable cage was associated with low PLIF-related complications compared to conventional cages.