L1-S1 Lordosis Research Articles

Cervical sagittal alignment in adult hyperkyphosis treated by posterior instrumentation and in situ bending

BackgroundIn the normal adult spine, a link between thoracolumbar and cervical sagittal alignment exists, suggesting adaptive cervical positional changes allowing horizontal gaze. In patients with thoracic hyperkyphosis, cervical adaptation to sagittal global alignment might be different from healthy individuals. However, this relationship has not clearly been reported in hyperkyphotic deformity. PurposeThe purpose of this study was to identify cervical sagittal alignment types observed on radiographs in young adults with thoracic hyperkyphosis. The relationship between cervical and thoracolumbar alignment as well as the effect of posterior instrumentation and adaptive positional changes of the mobile cervical segment were retrospectively analyzed. Patients and methodsTwenty-three patients (32.7 years; 5-year follow-up) were included. Full spine radiographic measurements were: T1 slope, T1-T4 kyphosis, T4-T12 kyphosis, L1-S1 lordosis, pelvic incidence, pelvic tilt, sacral slope, SVA C7, SVA C2, lordosis between C0-C2, C2-C7, C2-C4 and C4-C7. A Bayesian model and Spearman correlation were used. ResultsTwo alignment types existed: cervical lordosis (group A) and cervical kyphosis (group B). Preoperatively, T4-T12 kyphosis and L1-S1 lordosis were significantly higher in group A: 76.6° versus 59.4° and −72.8° versus −65.8° (probability of>5° difference P (β>5)>0.95). Pelvic incidence was higher in group A (49.8° versus 44.2°) and C0-C2 lordosis in group B (−29.4° versus −21.6°). A significant correlation existed between: T4-T12 kyphosis and C2-C7 lordosis, L1-S1 lordosis and pelvic incidence, C2-C7 lordosis and T1 slope, C2-C7 lordosis and T1-T4 kyphosis. Postoperatively, T4-T12 kyphosis decreased by 33.1° P (β>5)=0.9995), L1-S1 lordosis decreased by 17.7° (P (β>5)=0.961), T1-T4 kyphosis increased by 14.1° (P (β>5)=0.973). SVA C2 (translation) increased by 13.8mm. C0-C2 lordosis (head rotation) remained unchanged. Six patients changed cervical alignment. PJK occurred in 15 patients, unrelated to cervical alignment or proximal instrumentation level. DiscussionTwo cervical alignment types, lordotic or kyphotic, were observed thoracic hyperkyphosis patients. This alignment was mainly triggered by the amount of thoracic kyphosis and lumbar lordosis, linked to pelvic incidence. Moreover, the inclination of the C7-T1 junctional area plays a key role in the amount of cervical lordosis. The correction of T4-T12 kyphosis induced compensatory modifications at adjacent segments: T1-T4 kyphosis increase (PJK) and L1-S1 lordosis decrease. Global spino-pelvic alignment and head position did not change in the sagittal plane. The cervical spine tented to keep in its preoperative position in most patients. Level of evidenceLevel IV.

Effect of mono- or bisegmental lordosizing fusion on short-term global and index sagittal balance: a radiographic study.

Sagittal balance is widely recognized as an important outcome factor in reconstructive spinal surgery for lumbar degenerative conditions. However, its role in short segmental fixation is unknown. The aim of this study was to evaluate the preoperative and short-term postoperative spino-pelvic balance after short (1 or 2 levels) lordosizing lumbar fusion for degenerative disc disease (DDD). Twenty-six consecutive patients (13 males and 13 females) undergoing mono- or bisegmental lordosizing lumbar fusion (XLIF/TLIF) for lumbar DDD were included in the study. Clinical parameters were retrospectively collected from charts. Preoperative and early postoperative (6 weeks and 3 months) full-spine EOS X-rays were evaluated. Spinal parameters evaluating sagittal curvatures, pelvic orientation, global sagittal and coronal alignment, spino-pelvic balance, index level segmental lordosis and disc height were measured and statistically analyzed. A total of 16 TLIF and 10 XLIF procedures were performed. Eighteen were mono- and 8 were bisegmental fixations for a total of 34 fused segments. Seven patients (26.9%) showed a preoperative sagittal imbalance (defined as SVA>50 mm); 7 patients presented preoperative severe pelvic retroversion (defined as PT>20°) and 1 patient presented both. Disc height, intervertebral angle and segmental lordosis at the operated level significantly increased after surgery (P<0.01). No postoperative significant change in global sagittal alignment (SVA, TPA, T1SPi, T9SPi), pelvic orientation (SS, PT), coronal alignment, lumbar and L4-S1 lordosis and thoracic kyphosis have been observed. Mono- and bisegmental lordosizing fusion techniques, as XLIF and TLIF, are able to restore disc height and improve segmental lordosis. However they do not allow restoration of sagittal balance or improvement of compensatory mechanisms. A limited spinal reconstructive surgery on symptomatic levels can be reasonably proposed to patients with hidden or evident sagittal imbalance with any short-term radiographic impact.

How the type of sagittal alignment defined by Roussouly determines the gait of the asymptomatic adult subject

While curvatures of the sagittal spine are known to greatly differ among asymptomatic adult subjects, there are no studies that determine whether this heterogeneous normality affects gait. This study aimed to elucidate the relationships between normal sagittal spine profiles and gait in asymptomatic adult subjects. Ninety-one asymptomatic adult subjects (age = 21.6 ± 2.2, 47 M & 44F) with no prior orthopedic treatment underwent full body biplanar X rays with 3D reconstruction of the spine and pelvis. The following sagittal spino-pelvic parameters were generated from the 3D reconstructions: pelvic incidence, sacral slope, pelvic tilt, L1-L5 lordosis, L1-S1 lordosis, T1-T12 kyphosis and T4-T2 kyphosis. Lower limb kinematics was assessed using 3D gait analysis. Each subject was classified into one of the 4 types of normal sagittal alignment previously described by Roussouly. Kruskal-Wallis test was used to evaluate the differences in gait and spino-pelvic parameters between the Roussouly types. Seventeen subjects were classified as type 2, 47 as type 3, 26 as type 4 but only 1 as type 1. Therefore, Roussouly's type 1 was excluded from further analysis. Pelvic incidence (type 2: 41; type 3: 48; type 4: 56), sacral slope (type 2: 30; type 3: 38; type 4: 45), L1-L5 lordosis (type 2: 38; type 3: 48; type 4: 54) and L1-S1 lordosis (type 2: 50; type 3: 60; type 4: 67) differed significantly ( P P > 0.05) across the 3 types. Gait analysis revealed that type 2 subjects had the most retroverted pelvis during the gait cycle ( P = 0.02), the most elevated hip extension during stance phase ( P = 0.02) and the highest range of motion of ankle plantar-dorsiflexion during the gait cycle ( P = 0.01). Types 3 and 4 subjects had similar gait patterns with decreased pelvic retroversion during the gait cycle, decreased hip extension during the stance phase and decreased ankle plantar-dorsiflexion during the gait cycle compared to type 2 subjects. Sagittal spino-pelvic morphotypes seem to affect gait kinematics, even in asymptomatic subjects. Interestingly, different sagittal morphotypes seem to affect gait not only proximally (pelvis and hip) but also more distally (ankle). Future studies should determine whether sagittal malalignment and its surgical correction influence gait.

Spinal Instrumentation in Growing Children Retards the Natural Development of Pelvic Incidence.

Pelvic incidence increases gradually throughout growth until skeletal maturity. Growing rod instrumentation has been suggested to have a stabilizing effect on the development of the normal sagittal spinal alignment. The purpose of this study is to determine the effect of fixed sagittal plane caused by dual growing rod instrumentation on the natural progression of sagittal spinopelvic parameters in children with idiopathic or idiopathic-like early onset scoliosis. Hospital records of children with growing rod instrumentation from 4 separate institutions were reviewed retrospectively. Inclusion criteria were idiopathic or idiopathic-like early onset scoliosis, treatment with dual growing rods with lower instrumented vertebra L4 or upper and more than 2 years of follow-up. Instrumentation levels, magnitudes of major curve, thoracic kyphosis (T2-T12), lumbar lordosis (L1-S1) and pelvic incidence were recorded from preoperative and postoperative standing whole-spine radiographs. Estimated pelvic incidence was also calculated for each patient as if their spines had not been instrumented using the previous normative data. A total of 37 patients satisfied the inclusion criteria. Average age at initial surgery was 7.4±1.8 years (range, 4 to 12 y). Mean follow-up time was 71±26 months (range, 27 to 120 mo). Mean preoperative Cobb angle of 59±13.5 (range, 30 to 86) degrees was reduced to 35.1±17.5 (range, 11 to 78) degrees at the last follow-up. Mean preoperative T2-T12 kyphosis angle was 46.2±14.9 degrees (range, 22 to 84 degrees). At the latest follow-up, it was 44.8±16.2 degrees (range, 11 to 84 degrees) (P=0.93). Mean L1-S1 lordosis angle was 50.5±10.7 degrees (range, 30 to 72 degrees) preoperatively. At the latest follow-up, mean L1-S1 lordosis angle was 48.8±12.7 degrees (range, 26 to 74 degrees) (P=0.29). Mean preoperative pelvic incidence was 45.7±7.9 degrees (range, 30 to 68 degrees). At the latest follow-up, it was 46.7±8.4 degrees (range, 34 to 72 degrees) (P=0.303). The estimated average pelvic incidence was 49.5 degrees (P=0.012). Previously reported developmental changes of the sagittal spinal parameters were not observed in children who underwent posterior spinal instrumentation. Our findings suggest that spinal instrumentation impedes the natural development of the sagittal spinal profile. Level IV-this is a retrospective case-series.

Spinopelvic Alignment and Functional Outcome after Circumferential Fusion for Low-grade Isthmic Spondylolisthesis

Introduction Functional outcomes after surgery for low-grade isthmic spondylolisthesis(LGIS) is reported limitedly for combined posterior and anterior approach procedures. Imbalances in the sagittal alignment of spine and pelvis are increasingly seen as the reason for the development and progression of LGIS. Aims of this study: 1) functional outcome, 2) the effects on spinopelvic alignment, after circumferential fusion. Surgical treatment goals are restoration of stability, reduction of slippage, restoration of disc height and angulation, correction of spinopelvic parameters toward neutral values, and improve functional status. We hypothesized 1) a significant improvement on clinical outcome at 2-year follow-up and 2) a stable post-operative situation around the targeted vertebrae and restoration of the spinopelvic parameters to values seen in healthy subjects. Materials and Methods 43 subjects enrolled with LGIS at L5-S1. Each subject received a posterior decompression and pedicle screw instrumentation followed by an instrumented anterior lumbar interbody fusion in two separate procedures. (1) Outcome measures were registered pre-operative and after 12 and 24 months. Primary outcome was functional status (ODI). Secondary outcomes: Quality of Life (SF-36 subdomains, EQ-5D subscales), and pain intensity (VAS back and leg pain). (2) Full spine radiographs were taken pre-operative and after 3, 12, and 24 months postoperative. Obtained spinopelvic parameters are: sacral slope, pelvic tilt, pelvic incidence, thoracic kyphosis, L5-S1 lordosis, L1-S1 lordosis and sagittal vertical axis. The degree of slippage reduction and L5-S1 angular motion was measured. To evaluate both study aims a repeated measures ANOVA was used to indicate differences over time. Results 42 patients (25 female), average age 39,0 (25–51) with an average BMI 25,8 (21,5–30,4) participated in the study. Functional results are given as means with (standard deviation) pre-operative, at 12 months and 24 months postoperative for ODI: 35,0 (14,4); 10,0 (15,0); 9,5 (15,3); for SF-36 PCS: 42,0 (12,7); 70,5 (21,0); 71,5 (21,5); for SF-36 MCS: 64,0 (16,6); 81 (19,4); 81,5 (19,5); for EQ-5D: 0,56 (0,29); 0,84 (0,28); 0,83 (0,240); for VAS (back pain): 64,5 (26,2); 16,0 (32,2); 22,0 (23,9). Degree of slip decreased significantly from 27,0% (11,9%) to 7,4% (11,7%) postoperatively. Angular motion decreased statistically significant immediately postoperative and remained stable thereafter. L5-S1 and L1-S1 lordosis and sacral slope showed a significant increase postoperatively, whereas the pelvic tilt and sagittal vertical axis significantly decreased. Conclusion Circumferential instrumented fusion for LGIS via combined approach improves functional outcome at short term follow-up. After careful patient selection and unsuccessful conservative management surgical treatment is a suitable alternative with predictable short term outcome. Circumferential fusion corrects deformity and creates a stable situation in LGIS. We find that sagittal alignment is probably influenced positively, by bringing the SVA in a more neutral position.

Double-level degenerative spondylolisthesis: what is different in the sagittal plane?

Degenerative spondylolisthesis (DS) is a common disease. The importance of sagittal malalignment in the DS population has been widely described. However, there is no study reporting sagittal alignment analysis in double-level DS. This study aims to analyze patients with double-level DS and compare them with single-level DS patients in terms of demographic and radiographic data. Retrospective multicenter (n=13) study. Adult patients with one (uni_DS) or two-level DS (multi_DS) were included. Sagittal radiographic parameters were measured by an experienced observer: pelvic, spinal and global parameters with C7 sagittal tilt (C7 tilt, angle between the center of C7 vertebral body and the middle of the sacral endplate with the vertical reference line). After a descriptive analysis, radiographic and demographic data were compared between single and multi_DS. 78 patients were included in multi_DS group and 576 in uni_DS group. Multi_DS were older than uni_DS (70.2±9.4 vs 66.9±10.6years, p=0.009). C7tilt was greater in multi_DS (6.2°±5.3 vs. 4.8°±3.8, p=0.003). Multi_DS had a greater pelvic incidence (62.4°±11.3 vs. 58.3°±11.1, p=0.002). Pelvic tilt was larger in multi-DS (26.0°±7.5 vs. 22.6°±8.1, p=0.001). L4S1 lordosis represented 40.4% of the LLmax in multi_DS and 45.8% in uni_DS group (p=0.013). Multi_DS have different sagittal alignment than single DS with greater PI. In multi_DS, malalignment is more important with larger anterior tilt, loss of lumbosacral lordosis and more compensatory mechanisms such as pelvic retroversion. These findings highlight the need for an adapted surgical correction in these older patients with greater sagittal malalignment.

Comparison of Intraoperative Stitched Fluoroscopic Images to Postoperative Standing Full Spine Radiographs

Introduction Spinal deformity surgery requires assessment of correction achieved intraoperatively. Long cassette X-rays have been used in the past. Recent advances include availability of 3D scanners (e.g., O-arm). These are also able to take 2D images which can be stitched together to simulate full length X-rays. The process of “stitching” can be performed quickly and may potentially save time compared with conventional X-ray film developing. This is the first study to look at correlation between stitched O-arm fluoroscopic images and postoperative standing X-rays. Methods Patients who underwent fusion of ≥ 3 levels for coronal/sagittal deformity and who had intraoperative stitched O-arm images were identified. The intraoperative images and postoperative full-spine X-rays were reviewed. Coronal and sagittal curves and balance were measured by and averaged between two independent observers. Correlation between intra- and postoperative parameters was tested by computation of Pearson coefficient. Results Between March 2011 and June 2013, 80 patients met the inclusion criteria. Mean age was 27 years (range, 6–85 years). Correlation between intraoperative stitched images and postoperative full-length films was very strong for focal curve measurements at the operative levels (major curve Cobb r = 0.90, lordosis/kyphosis across instrumented levels r = 0.74, T5–T12 kyphosis r = 0.88). However, global balance parameters and regional lordosis were found to either have poor correlation (shoulder–pelvis balance 0.41, L1–S1 lordosis 0.62) or were not measurable on the stitched images (T1–pelvic angle). Conclusion Intraoperative AP and lateral stitched O-arm images correlated strongly with postoperative full-spine standing X-rays for focal angular measurements, such as major curve coronal Cobb angles, instrumented level lordosis, and mid-thoracic (T5–T12) kyphosis. However, global balance parameters, such as shoulder–pelvis balance and T1–pelvic angle, cannot be reliably measured on stitched images. This may be either because of differences between prone and upright positioning, image quality, technique of stitching, or the inability to include the entire spine and pelvis in the images.

Cervical sagittal alignment in idiopathic scoliosis treated by posterior instrumentation and in situ bending.

Retrospective radiographical analysis of cervical and thoracolumbar sagittal alignment in young adults with idiopathic scoliosis. To analyze cervical alignment types, the relationship between cervical and thoracolumbar alignment and the effect of posterior instrumentation. Thoracic scoliosis with hypokyphosis may decrease cervical lordosis. Additional adaptive positional changes of the mobile cervical segment may exist, because sigmoid cervical patterns are observed. Sagittal alignment of the instrumented thoracolumbar spine may influence cervical alignment. Pre- and postoperative full-spine radiographs of 52 patients were analyzed at 8-year average follow-up. Sagittal thoracolumbar measurements were T1 slope, T1-T4 kyphosis, T4-T12 kyphosis, L1-S1 lordosis, pelvic incidence, pelvic tilt, sacral slope, sagittal vertical axis (SVA) C7, and SVA C2. Cervical measurements were C0-C2, C2-C6, C2-C4, C4-C6, and C2-T1 lordosis, chin-brow vertical angle. Five cervical alignment types were identified: lordotic, hypolordotic, kyphotic, sigmoid with cranial lordosis, and sigmoid with cranial kyphosis. Spinopelvic parameters and global thoracolumbar balance remained unchanged postoperatively. The average C2-C6 lordosis increased by 6.4° (P < 0.0001). Twenty-seven of the 52 patients changed cervical alignment postoperatively. SVA C2-C7 difference changed in this subgroup (P = 0.0159). In 21 of the 27 patients, SVA changed more than 5 mm at C2 (P = 0.0029), and in 25 of the 27 patients at C7 (P < 0.0001). A correlation existed between T4-T12 kyphosis and L1-S1 lordosis, C2-C4 and L1-S1 lordosis, L1-S1 lordosis, and pelvic tilt. T1-T4 kyphosis and T1 slope correlated with C2-T1 lordosis, but proximal junctional kyphosis was not linked to a specific cervical alignment type. Postoperative adaptive changes occurred at C7 and C2 by shifting anteriorly or posteriorly, resulting in different radiographical cervical shapes. The amount of lumbar lordosis may influence cervical lordosis, which needs to be considered for surgical correction. Adaptive hip movements may influence thoracolumbar and cervical alignment. The amount of proximal thoracic kyphosis influenced cervical lordosis. Global thoracic hypokyphosis might influence cervical alignment, but it was not evidenced. 4.

Posterior surgery in high-grade spondylolisthesis

IntroductionHigh-grade L5-S1 spondylolisthesis alters sagittal spinopelvic balance, which can cause low back pain and progressive neurologic disorder. The present study assessed spondylolisthesis reduction and maintenance over time with L4-S1 versus L5-S1 fusion using a lever-arm system and posterior fusion combined with lumbosacral graft. Materials and methodsForty patients were operated on for symptomatic high-grade spondylolisthesis, 34 of whom had full pre- and post-operative radiological analysis, with a mean follow-up of 5.4years. There were 9 L5-S1 and 25 L4-S1 instrumentations. Analysis of spinopelvic and slipping parameters and the evolution of segmental lordosis compared results between L5-S1 and L4-S1 instrumentation. ResultsMean Taillard spondylolisthesis index decreased from 64% to 37% (P=0.0001). Overall sagittal spinopelvic balance was not significantly changed. Overall L1-S1 and segmental L4-L5 lordosis were not affected by instrumentation. Mean L5-S1 segmental lordosis increased from 11° to 18°. There was loss of reduction from 19° to 14° with L5-S1 instrumentation, in contrast to maintained reduction with L4-S1 instrumentation (P=0.006). ConclusionThe lever-arm system provided anterior-posterior reduction of spondylolisthesis and corrected slippage. Postoperative change in overall sagittal spinopelvic balance was slight and constant. Posterior L4-S1 fusion provided better long-term control of L5-S1 lordosis reduction than the shorter L5-S1 fusion.Retrospective study of level IV.

Radiographic and clinical outcome after 1- and 2-level transsacral axial interbody fusion

The paracoccygeal approach allows for instrumentation of L5/S1 and L4/5 by using a transsacral rod (AxiaLIF; TransS1, Inc.). The authors analyzed clinical and radiographic outcomes of 1- or 2-level AxiaLIF procedures with focus on durability of the construct. This was a retrospective study of 38 consecutive patients who underwent either 1-level (32 patients) or 2-level (6 patients) AxiaLIF procedures at the authors' institution. The Oswestry Disability Index (minimum clinically important difference [MCID] ≥ 12) and visual analog scale ([VAS]; MCID ≥ 3) scores were collected. Disc height and Cobb angles were measured on pre- and postoperative radiographs. Bony fusion was determined on CT scans or flexion/extension radiographs. Implantation of a transsacral rod allowed for intraoperative distraction of the L5/S1 intervertebral space and resulted in increased segmental lordosis postoperatively. At a mean follow-up time of 26.2 ± 2.4 months, however, graft subsidence (1.9 mm) abolished partial correction of segmental lordosis. Moreover, subsidence of the construct reduced L5/S1 lordosis in patients with 1-level AxiaLIF by 3.2° and L4-S1 lordosis in patients with 2-level procedures by 10.1° compared with preoperative values (p < 0.01). Loss of segmental lordosis predicted failure to improve VAS scores for back pain in the patient cohort (p < 0.05). Overall, surgical intervention led to modest symptomatic improvement; only 26.3% of patients achieved an MCID of the Oswestry Disability Index and 50% of patients an MCID of the VAS score for back pain. At last follow-up, 71.9% of L5/S1 levels demonstrated bony fusion (1-level AxiaLIF 80.8%, 2-level AxiaLIF 33.3%; p < 0.05), whereas none of the L4/5 levels in 2-level AxiaLIF fused. Five constructs developed pseudarthrosis and required surgical revision. The AxiaLIF procedure constitutes a minimally invasive technique for L5/S1 instrumentation, with low perioperative morbidity. However, the axial rod provides inadequate long-term anterior column support, which leads to subsidence and loss of segmental lordosis. Modification of the transsacral technique to allow for placement of a solid interposition graft may counteract subsidence of the construct.

Sagittal Balance Improvement in Surgical Treatment of Low- Grade Isthmic Lumbosacral Spondylolisthesis

Background Data: The role of surgical correction of sagittal plane deformity in cases of lytic spondylolisthesis is essential. While evidence is emerging of the possible short- and long-term benefits of restoring spinal balance, some surgeonshave been concerned about the associated risks especially if instrumentation has to be used for reduction of the slipping.Purpose: To evaluate the Sagittal Balance improvement in surgical Treated Lowgrade Isthmic Lumbosacral Spondylolisthesis Study Design: Prospective clinical case study Patients and Methods: Twenty two patients with low-grades (<50%) of isthmic spondylolisthesis of lumbosacral junction (L5-S1) were managed by a surgical intervention aiming for correction of the deformity even with partial reduction of the slipping. Sagittal alignment at the lumbosacral junction was tried to be achieved by appropriate positioning of the patient during the surgery and by rod contouring. Posterior decompression of nerve structures by laminectomy in conjunction with posterior instrumented fusion from L5 to sacrum were also done. They were fourteen females and eight males with a mean age of 40.45 years. The mean follow up period was 20 months. Results: All patients achieved satisfactory results as regards the back pain, radicular pain and neurologic deficits. The mean preoperative estimated values of slip percentage, L1-S1 lordosis, sacral inclination angle and lumbosacral kyphosis were 30.2%, 48.8°, 46.04°, and 35°. The mean reconstructed values were 25%, 34.9°, 36.86°, and 28° postoperative. Pelvic version improved in patients with unbalanced spondylolisthesis as evidenced by decreased sacral slope [from 46.04 degrees to 36.86 degrees] (P<0.5). All patients could return to their normal activities of daily living.Conclusion: This study suggests that, the described technique can yield satisfactory clinical outcomes and substantial deformity correction using single posterior approach with proper patient position before surgery. (2013ESJ040)

Sagittal Balance Improvement in Surgical Treatment of Low- Grade Isthmic Lumbosacral Spondylolisthesis

Background Data: The role of surgical correction of sagittal plane deformity in cases of lytic spondylolisthesis is essential. While evidence is emerging of the possible short- and long-term benefits of restoring spinal balance, some surgeonshave been concerned about the associated risks especially if instrumentation has to be used for reduction of the slipping.Purpose: To evaluate the Sagittal Balance improvement in surgical Treated Lowgrade Isthmic Lumbosacral Spondylolisthesis Study Design: Prospective clinical case study Patients and Methods: Twenty two patients with low-grades (<50%) of isthmic spondylolisthesis of lumbosacral junction (L5-S1) were managed by a surgical intervention aiming for correction of the deformity even with partial reduction of the slipping. Sagittal alignment at the lumbosacral junction was tried to be achieved by appropriate positioning of the patient during the surgery and by rod contouring. Posterior decompression of nerve structures by laminectomy in conjunction with posterior instrumented fusion from L5 to sacrum were also done. They were fourteen females and eight males with a mean age of 40.45 years. The mean follow up period was 20 months. Results: All patients achieved satisfactory results as regards the back pain, radicular pain and neurologic deficits. The mean preoperative estimated values of slip percentage, L1-S1 lordosis, sacral inclination angle and lumbosacral kyphosis were 30.2%, 48.8°, 46.04°, and 35°. The mean reconstructed values were 25%, 34.9°, 36.86°, and 28° postoperative. Pelvic version improved in patients with unbalanced spondylolisthesis as evidenced by decreased sacral slope [from 46.04 degrees to 36.86 degrees] (P<0.5). All patients could return to their normal activities of daily living.Conclusion: This study suggests that, the described technique can yield satisfactory clinical outcomes and substantial deformity correction using single posterior approach with proper patient position before surgery. (2013ESJ040)

Clinical efficacies of skipping two-level transpedicular wedge osteotomy for correction of severe kyphosis in ankylosing spondylitis

To explore the clinical efficacies of skipping two-level transpedicular wedge osteotomy in the correction of severe kyphotic deformity in ankylosing spondylitis (AS). From January 2003 to December 2009, a total of 38 consecutive patients with AS and severe kyphosis (chin-brow vertical angle (CBVA) or global thoraco-lumbar kyphosis angle (TLKA) over 70°) undergoing skipping two-level transpedicular wedge osteotomy at the Department of Orthopedics of Chinese PLA General Hospital were reviewed retrospectively. There were 32 males and 6 females with an average age of 38.0 years (range: 22 - 65). The preoperative parameters of TLKA, T11-L2 kyphotic angle, L1-S1 lordosis angle, sagittal imbalance and CBVA were obtained from the total spine radiography or computed tomography and clinical lateral photograph. According to the characteristic curves and normal spinal alignment, their profiles of osteotomy location and angle were determined and confirmed by computer simulations. Improvement in postoperative parameters was observed and treatment satisfaction evaluated The average operating duration was 309 minutes and the average volume of blood loss was 2050 ml. The parameters of TLKA, T11-L2 kyphotic angle and L1-S1 lordosis angle improved from 101.0° ± 21.3°, 45.2° ± 13.6°, -28.2° ± 23.3° at preoperation to 26.0° ± 12.1°, 2.8° ± 11.6°, 28.9° ± 13.3° postoperation respectively (P < 0.01). CBVA improved from 79.4° ± 15.9° to 13.6 ° ± 10.9° (P < 0.01). The sagittal imbalance distance improved from (49 ± 13) to (15 ± 7) cm (P < 0.01). All patients could walk with orthophoria and lie horizontally postoperatively. The average follow-up was 32 months (range: 24 ∼ 78 months). Fusion of osteotomy was achieved in all patients and there was no event of loss of correction or implant failure. The SRS-22 average score improved from 1.8 to 4.2. For severe kyphosis in AS, skipping two-level transpedicular wedge osteotomy is a satisfactory and reliable approach for the correction of kyphotic deformity and it may improve appearance and function significantly.

Quality Control of Reconstructed Sagittal Balance for Sagittal Imbalance

Prospective radiographic study. To investigate the feasibility of controlling quality of reconstructed sagittal balance for sagittal imbalance. Patients with sagittal imbalance cannot walk or stand erect without overwork of musculature because of compromised biomechanical advantage. The result is muscle fatigue and activity-related pain. During reconstructive surgery, restoration of optimal sagittal balance is crucial for obtaining satisfactory clinical results. However, there is no way to control quality of reconstructed sagittal balance before or during surgery. A method was developed to determine the lumbosacral curve in a way that theoretically would bring sagittal balance to an ideal state by calculation and simulation for each patient before surgery and then template rods of the curve and a blueprint were made accordingly for operative procedures. Ninety-four consecutive patients with sagittal imbalance due to lumbar kyphosis were treated for intractable pain and then followed up for a mean of 4.3 years. Radiographs were analyzed before surgery, 2 months after surgery, and at most recent follow-up. The mean estimated values of L1-S1 lordosis, sacral inclination angle, sacrofemoral distance, and distribution of L1-S1 lordosis at the closing-opening wedge osteotomy site and L4-S1 segments were 30.8°, 24.6°, 0 mm, 16.1% (-5°), and 62% (-19°), respectively. The mean reconstructed values were 41.1°, 23.3°, 3.9 mm, 41% (-17°), and 46% (-19°), respectively. There were significant differences between estimated and reconstructed values of L1-S1 lordosis and the percentage of distributions; however, there was no significant difference between the estimated and reconstructed magnitude of L4-S1 lordosis, sacral inclination angle, and sacrofemoral distance. A properly oriented pelvis can be brought nearly directly above the hip axis. The mean sagittal global balance, represented by the distance between the vertical line through the hip axis and sacral promontory, improved from 61.4 mm before surgery to 3.9 mm 2 months after surgery, and 1.3 mm at final follow-up. Normal sagittal global balance was reconstructed and maintained. The mean sagittal spinal balance measured as the horizontal distance between the C7 sagittal plumb line and the posterior superior corner of S1 improved from 97.4 mm before surgery to 11 mm 2 months after surgery. However, there was significant loss of sagittal spinal balance to 25.4 mm at the fi nal visit. Normal sagittal spinal balance was reconstructed and appeared to be maintained. The magnitude of T1-T12 kyphosis compensated from 13° before surgery to 25.2° 2 months after surgery and 34.5° at fi nal follow-up. Quality control of the reconstructed sagittal balance for sagittal imbalance is possible. Correctly orienting the pelvis, reconstructed by the restoration of enough L1-S1 lordosis with adequate distribution at L4-S1 segments, is a matter of critical importance for optimizing reconstructed sagittal balance. The correctly oriented pelvis can be determined before surgery. Preventing junctional fracture and persistent rehabilitation of surgically injured lumbar extensor musculature are crucial for maintaining the reconstructed sagittal balance.

Sagittal spinopelvic alignment and body mass index in patients with degenerative spondylolisthesis

The sagittal orientation and osteoarthritis of facet joints, paravertebral muscular dystrophy and loss of ligament strength represent mechanical factors leading to degenerative spondylolisthesis. The importance of sagittal spinopelvic imbalance has been described for the developmental spondylolisthesis with isthmic lysis. However, it remains unclear if these mechanisms play a role in the pathogenesis of degenerative spondylolisthesis. The purpose of this study was to analyze the sagittal spinopelvic alignment, the body mass index (BMI) and facet joint degeneration in degenerative spondylolisthesis. A group of 49 patients with L4-L5 degenerative spondylolisthesis (12 males, 37 females, average age 65.9 years) was compared to a reference group of 77 patients with low back pain without spondylolisthesis (41 males, 36 females, average age 65.5 years). The patient's height and weight were assessed to calculate the BMI. The following parameters were measured on lateral lumbar radiographs in standing position: L1-S1 lordosis, segmental lordosis from L1-L2 to L5-S1, pelvic tilt, pelvic incidence and sacral slope. The sagittal orientation and the presence of osteoarthritis of the facet joints were determined from transversal plane computed tomography (CT). The average BMI was significantly higher (P=0.030) in the spondylolisthesis group compared to the reference group (28.2 vs. 24.8) and 71.4% of the spondylolisthesis patients had a BMI>25. The radiographic analysis showed a significant increase of the following parameters in spondylolisthesis: pelvic tilt (25.6° vs. 21.0°; P=0.046), sacral slope (42.3° vs. 33.4°; P=0.002), pelvic incidence (66.2° vs. 54.2°; P=0.001), L1-S1 lordosis (57.2° vs. 49.6°; P=0.045). The segmental lumbar lordosis was significantly higher (P<0.05) at L1-L2 and L2-L3 in spondylolisthesis. The CT analysis of L4-L5 facet joints showed a sagittal orientation in the spondylolisthesis group (36.5° vs. 44.4°; P=0.001). The anatomic orientation of the pelvis with a high incidence and sacral slope seems to represent a predisposing factor for degenerative spondylolisthesis. Although the L1-S1 lordosis keeps comparable to the reference group, the increase of pelvic tilt suggests a posterior tilt of the pelvis as a compensation mechanism in patients with high pelvic incidence. The detailed analysis of segmental lordosis revealed that the lordosis increased at the levels above the spondylolisthesis, which might subsequently increase posterior stress on facet joints. The association of overweight and a relatively vertical inclination of the S1 endplate is predisposing for an anterior translation of L4 on L5. Furthermore, the sagittally oriented facet joints do not retain this anterior vertebral displacement.

Study of distal junctional kyphosis of adolescent idiopathic scoliosis following anterior or posterior selective instrumented fusion and its risk factors.

Objective To compare the sagittal measurements before and after surgery in patients with adolescent idiopathic scoliosis (AIS) treated with instrumented fusion, and determine the incidence of distal junctional kyphosis (DJK) and its risk factors. Methods Fifty-nine patients with Lenke 1 type A1S underwent anterior or posterior instrumented fusion. In anterior group, including thoracoscopic surgery in 8 cases and mini-open surgery in 19 cases, while in posterior group, including 13 cases with distal pedicle screw fixation and 19 cases with hook constructs. The standing long-cassette anteroposterior and lateral radiographs of spine were taken, and the coronal and sagittal parameters were measured before and after surgery and during follow-up. Results At recent follow-up, the T5-T12, T10,-L2 sagittal measurement and DJK of anterior group increased significantly versus preoperation, the T5-T12 kyphosis, T10,-L2 kyphosis, DJK and L1-S1 lordosis of posterior hook group increased significantly versus preoperation. The postoperative mean T10,-L2 kyphosis and DJK in the posterior hook group were 13.1° and 8.7° compared to 0.1° and -2.2° in the posterior distal pedicle screw group. When postoperative DJK developed in the posterior group, mean postoperative T5-T12 kyphosis, T10,-L2 kyphosis and L1-S1, lordosis 18.5°, 13.6° and 51.1°versus 11.6°, 0.5° and 42.2° preoperatively. When postoperative DJK developed in the posterior group, mean postoperative T10,-L2 was 13.6° kyphosis compared to 2.6° in the posterior group without DJK. Conclusion The AIS patients undergoing selective anterior fusion may develop sagittal decompensation in distal junctional segments without instrumentation for its risk factor of short fusion segments. The AIS patients undergoing selective posterior hook instrumented fusion may develop sagittal decompensation for its risk factor of instability. Key words: Scoliosis; Adolescent; Spinal fusion; Kyphosis

The sagittal balance of the spine in children and adolescents with osteogenesis imperfecta

In severe forms of osteogenesis imperfecta, multiple compression fractures of the spine, as well as vertebral height shortening could be responsible for an increased thoracic kyphosis or a diminished lumbar lordosis. Theses progressive changes in sagittal shapes of the trunk could be responsible for a global sagittal trunk imbalance. We compare the parameters of sagittal spinopelvic balance in young patients with OI to those parameters in a control group of healthy volunteers. Eighteen patients with osteogenesis imperfecta were compared to a cohort of 300 healthy volunteers. A standing lateral radiograph of the spine was obtained in a standardized fashion. The sacral slope, pelvic tilt, pelvic incidence, lumbar lordosis, thoracic kyphosis, T1 and T9 sagittal offset were measured using a computer-assisted method. The variations and reciprocal correlations of all parameters in both groups according to each other were studied. Comparison of angular parameters between OI patients and control group showed an increased T1T12 kyphosis in OI patients. T1 and T9 sagittal offset was positive in OI patients and negative in control group. This statistically significant difference among sagittal offsets in both groups indicated that OI patients had a global sagittal balance of the trunk displaced anteriorly when compared to the normal population. Reciprocal correlations between angular parameters in OI patients showed a strong correlation between lumbar lordosis (L1L5 and L1S1) and sacral slope. The T9 sagittal offset was also strongly correlated with pelvic tilt. Pelvic incidence was correlated with L1S1 lordosis, T1 sagittal offset and pelvic tilt. In OI patients, the T1T12 thoracic kyphosis was statistically higher than in control group and was not correlated with other shape (LL) or pelvic (SS, PT or PI) parameters. Because isolated T1T12 kyphosis increase without T4T12 significant modification, we suggest that vertebral deformations worsen in OI patients at the upper part of thoracic spine. Further studies are needed to precise the exact location of most frequent vertebral deformities.

A Lumbar Classification of Scoliosis in the Adult Patient: Preliminary Approach

Retrospective consecutive clinical review of 98 patients. To create a preliminary approach to a clinically important classification of scoliosis in adult patients. There is currently no accepted classification of scoliosis in adults. High prevalence rates of scoliosis in the elderly and recent studies of health impact support the need for a clinically relevant classification. A total of 98 adult patients with scoliosis with a 2-year minimum treatment/follow-up were included. Patients were classified into one of 3 types of deformity based on the degree of lordosis (L1-S1) and frontal plane endplate obliquity of L3 on standing radiographs: type I = lordosis > 55 degrees, L3 obliquity < 15 degrees; type II = lordosis 35 degrees-55 degrees, L3 obliquity 15 degrees-25 degrees; and type III = lordosis < 35 degrees, L3 obliquity > 25 degrees. Curve patterns included thoracic, thoracolumbar, lumbar, thoracic, and lumbar (mean Cobb angle 30 degrees, standard deviation 19 degrees). Cobb angle revealed no correlation to visual analog pain score (VAS) or general health (36-Item Short-Form Health Survey). Significant correlation between endplate obliquity L3, L1-S1 lordosis and VAS was noted (P < 0.05). Mean pain scores of classified patients were: type I, VAS = 27.7; type II, VAS = 43.3; and type III, VAS = 47.1 (type I vs. III, P < 0.05). Surgical rates (failed minimum 3-month conservative care, including bracing, physical therapy, and pharmacological treatment) by group were: type I, 0%; type II, 9%; and type III, 22.7% (P = 0.002). A simple classification of adult scoliosis was developed based on frontal and sagittal plane standing radiographs. With increasing type (from I to III), self-reported pain and disability increased. This result was reflected in the treatment approach as well, with surgical rates increasing from types I to III. Further refinement is important to develop an all inclusive and sufficiently descriptive system.

Effect of torso flexion on the lumbar torso extensor muscle sagittal plane moment arms

BACKGROUND CONTEXT: Accurate anatomical inputs for biomechanical models are necessary for valid estimates of internal loading. The magnitude of the moment arm of the lumbar erector muscle group is known to vary as a function of such variables as gender. Anatomical evidence indicates that the moment arms decrease during torso flexion. However, moment arm estimates in biomechanical models that account for individual variability have been derived from imaging studies from supine postures. PURPOSE: Quantify the sagittal plane moment arms of the lumbar erector muscle group as a function of torso flexion, and identify individual characteristics that are associated with the magnitude of the moment arms as a function of torso flexion. STUDY DESIGN/SETTING: Utilization of a 0.3 Tesla Open magnetic resonance image (MRI) to image and quantify the moment arm of the right erector muscle group as a function of gender and torso flexion. METHODS: Axial MRI images through and parallel to each of the lumbar intervertebral discs at four torso flexion angles were obtained from 12 male and 12 female subjects in a lateral recumbent posture. Multivariate analysis of variance was used to investigate the differences in the moment arms at different torso flexion angles, whereas hierarchical linear regression was used to investigate associations with individual anthropometric characteristics and spinal posture. RESULTS: The largest decrease in the lumbar erector muscle group moment arm from neutral to 45-degree flexion occurred at the L5–S1 level (9.7% and 8.9% for men and women, respectively). Measures of spinal curvature (L1–S1 lordosis), body mass and trunk characteristics (depth or circumference) were associated with the varying moment arm at most lumbar levels. CONCLUSIONS: The sagittal plane moment arms of the lumbar erector muscle mass decrease as the torso flexes forward. The change in moment arms as a function of torso flexion may have an impact on prediction of spinal loading in biomechanical models.

Anterior Correction of Idiopathic Scoliosis Using TSRH Instrumentation

The first 14 consecutive patients with idiopathic lumbar scoliosis treated by anterior Texas Scottish Rite Hospital (TSRH) instrumentation are reported. Frontal curve correction averaged 76%, with a 5 degrees (9%) loss of correction in the follow-up period, which averaged 17.6 months (range, 12-29). Spinal balance was improved an average of 1.8 cm toward the center sacral line, and apical vertebral rotation was corrected an average of 49%. Instrumentational kyphosis was minimal, with total L1-S1 lordosis decreasing an average of 1 degree, and no measured compensatory hyperlordosis caudal to the instrumented segment. One hundred percent of disc spaces were radiographically fused by 8 months. There were no neurologic, septic, or implant complications. The contoured solid rod used in this construct provides the same frontal and rotatory correction as previous systems, and minimizes instrumentational kyphosis. Fusion occurs rapidly and reliably because of the stiffness of the construct, which also may eliminate the need for postoperative immobilization.