Segmental Sagittal Alignment Research Articles

Defining the "Three-Dimensional Sagittal Plane" in Thoracic Adolescent Idiopathic Scoliosis.

Obtaining accurate measurements of scoliosis from two-dimensional (2-D) radiographs can be challenging because of the three-dimensional (3-D) nature of the deformity. Previous studies have shown that the sagittal plane, in particular, is misrepresented on 2-D radiographs because of the influence of axial plane rotation. The purpose of the current study was to define a methodology for measuring the 3-D segmental sagittal alignment of the spine in patients with adolescent idiopathic scoliosis (AIS) and to assess the effect of axial plane rotation on differences between 3-D and 2-D measures of deformity. Preoperative and postoperative EOS images of 120 consecutive patients with AIS (primary thoracic curves) treated with segmental thoracic pedicle-screw instrumentation were analyzed in the "3-D sagittal plane." The technique measured 3-D kyphosis or lordosis in the specific plane of sagittal motion for each spinal motion segment. The kyphosis (+) and lordosis (-) values of the segments from T5 to T12 were summed to give the 3-D measurement of T5-T12 kyphosis. These values were compared with the standard 2-D measurements of T5-T12 kyphosis on lateral radiographs, and a correlation analysis with regard to axial plane rotation of the apex was performed. The average age (and standard deviation) of the patients was 14 ± 2 years. The mean preoperative Cobb angle on the standard 2-D view was 55° ± 10° and on the 3-D view was 52° ± 9° (p ≤ 0.001). On the 3-D view, the mean preoperative T5-T12 kyphosis was 6° ± 14°, and the kyphosis significantly increased to 26° ± 6° postoperatively (p < 0.001). The T5-T12 kyphosis on the standard 2-D view measured 18° ± 13° preoperatively and 27° ± 6° postoperatively (p < 0.001). The difference between the 2-D and 3-D measurements of T5-T12 kyphosis strongly correlated with apical vertebral rotation (r = 0.85; p < 0.01). Routine 2-D measurements of thoracic kyphosis erroneously underestimate the preoperative loss of kyphosis in AIS because of errors associated with axial plane rotation, an inherent component of thoracic scoliosis.

Restoration of Lumbopelvic Sagittal Alignment and its Maintenance following Transforaminal Lumbar Interbody Fusion (TLIF): Comparison between Straight Type versus Curvilinear Type Cage

The interbody cage used in TLIF not only provides anterior column support, but also can act as a fulcrum with subsequent compression of the pedicle screw (cantilever effect) to induce lordosis and improvement of segmental sagittal alignment. Although acceptable fusion rates and favorable clinical outcomes of TLIF have been well documented, major concern lies on restoring and maintaining the lumbopelvic sagittal alignment postoperatively. Besides, little is known about the impact of shape, position and structural characteristics of interbody cage on lumbopelvic sagittal alignment in TLIF procedure

Adjacent segment degeneration after single-level anterior cervical decompression and fusion: Disc space distraction and its impact on clinical outcomes

The purpose of this study was to find whether excessive distraction of the disc space for cage insertion was a risk factor for adjacent segment degeneration (ASD) after anterior cervical decompression and fusion (ACDF). One hundred and sixteen consecutive patients who underwent ACDF for single-level cervical disc herniation between June 2006 and November 2008 were retrospectively reviewed. Preoperative, postoperative and final follow-up disc height (DH), sagittal segmental alignment (SSA), and sagittal alignment of the cervical spine (SACS) were measured and compared between the ASD group and non-ASD group. In 116 patients, ASD was radiographically proven in 28 (24.1%) patients. The clinical outcomes were significantly improved compared to the preoperative scores in both groups. However, the postoperative and final follow-up DH of the ASD group were significantly higher than in the non-ASD group (p<0.05). In addition, the postoperative DH was significantly correlated with the postoperative or final follow-up SSA (p<0.05). However, postoperative DH was not found to significantly correlate with postoperative or final follow-up SACS (p=0.072 and p=0.096, respectively). Multivariate analysis showed that postoperative DH was the most significant risk factor for ASD. The clinical outcomes of ACDF for single-level degenerative cervical disc disease were satisfactory. Postoperative DH (the distracted distance) had the greatest impact on the incidence of ASD. Excessive disc space distraction is a considerable risk factor for the development of radiographic ASD.

Hybrid Circumferential Fixation for Degenerative Lumbosacral Spine Disease

Retrospective study on circumferential hybrid instrumentation with posterior lumbar interbody fusion (PLIF) and the novel posterior Universal Clamp (UC) instrumentation. This study evaluated the roentgenographic and clinical outcome after PLIF with PEEK cage augmented with UC posterior sublaminar fixation without posterior fusion. Although UC has been successfully used in scoliosis surgery, to our knowledge, this is the first report on its use in degenerative lumbosacral disease. Rigid pedicle screw lumbosacral fixation is associated with several intraoperative screw-related complications. The use of sublaminar bands and rods combined with PEEK PLIF should increase fusion rate and avoid screw-related complications. From a total of 295 consecutive patients who experienced degenerative lumbosacral disease and received posterior decompression, implantation of PLIF with PEEK cages and semirigid posterior fixation with sublaminar UC bands-rods without posterolateral fusion, 150 patients were eligible for this study with a follow-up of more than 2 years. Interbody fusion rate and global plus segmental sagittal spinal lordosis restoration were recorded pre- and postoperatively. Visual analogue scale and Oswestry Disability Index were used to assess functional outcome. Hybrid instrumentation expanded over 1 to 5 levels. Surgical time ranged from 45 to 225 minutes. Only 12.6% of the patients were transfused. There was no nerve root lesion or deep wound infection. Laminar fracture occurred intraoperatively in one case during band insertion. Interbody fusion was achieved in 94% of the operated segments. Lumbar lordosis improved from -36 ± 9° preoperatively to -53 ± 6° postoperatively. Segmental lordosis improved in L4-L5 segment from -5 ± 3° preoperatively to -12 ± 2° postoperatively and in L5-S1 from -9 ± 4° to -14 ± 2° postoperation. Oswestry Disability Index score improved from 44.9 preoperatively to 2.2 postoperatively (P < 0.001). No patient required further spinal surgery until the final evaluation. UC, a novel semirigid sublaminar posterior instrumentation, combined with wedge-shaped PEEK PLIF corrected both global and segmental sagittal lumbar alignment and achieved fusion rate similar to that historically reported with pedicle screw-PLIF techniques, however, avoiding intraoperative complications associated with the use of pedicle screws.

Safety and Efficiency of Biomimetic Nanohydroxyapatite/Polyamide 66 Composite in Rabbits and Primary Use in Anterior Cervical Discectomy and Fusion

This study was conducted to validate the safety and efficiency of biomimetic nanohydroxyapatite/polyamide 66 (n-HA/PA66) composite in animal model (rabbit) and report its application in anterior cervical discectomy and fusion (ACDF) for 4, 12, and 24 weeks. N-HA/PA66 composite was implanted into one-side hind femur defects and the control defects were kept empty as blank controls. A combination of macroscopic and histomorphometric studies was performed up to 24 weeks postoperatively and compared with normal healing. 60 cervical spondylosis myelopathy and radiculopathy patients who were subjected to ACDF using n-HA/PA66 and PEEK cage were involved in this study with six-month minimum follow-up. Their radiographic (cage subsidence, fusion status, and segmental sagittal alignment (SSA)) and clinical (VAS and JOA scales) data before surgery and at each follow-up were recorded and compared. Nanohydroxyapatite/polyamide 66 composite is safe and effective in animal experiment and ACDF.

Comparison of anterior cervical fusion by titanium mesh cage versus nano-hydroxyapatite/polyamide cage following single-level corpectomy

The titanium mesh cage (TMC) is a typical metal cage device which has been widely used in cervical reconstruction for decades. Nano-hydroxyapatite/polyamide-66 (n-HA/PA66) cage is a novel biomimetic non-metal cage device growing in popularity in many medical centres in recent years. There has been no comparison of the efficacy between these two anterior reconstructing cages. The purpose of this study was to compare the radiographic and clinical outcomes of these two different devices. Sixty-seven eligible patients with single-level ACCF using TMC or n-HA/PA66 cage for cervical degenerative diseases, with four-year minimum follow-up, were included in this prospective non-randomised comparative study. Their radiographic (cage subsidence, fusion status, segmental sagittal alignment [SSA]) and clinical (VAS and JOA scales) data before surgery and at each follow-up was recorded completely. The fusion rate of the n-HA/PA66 group was higher than TMC at one year after surgery (94% vs. 84%) though their finial fusion rates were similar (97% vs. 94%). Finial n-HA/PA66 cage subsidence was 1.5 mm with 6% of severe subsidence over three millimetres, which was significantly lower than the respective 2.9 mm and 22% of TMC (P < 0.0001). Lastly, SSA, VAS and JOA in TMC group were worse than in the n-HA/PA66 group (P = 0.235, 0.034 and 0.007, respectively). The n-HA/PA66 cage is associated with earlier radiographic fusion, less subsidence and better clinical results than TMC within four years after one-level ACCF. With the added benefit of radiolucency, the n-HA/PA66 cage may be superior to TMC in anterior cervical construction.

In-hospital postoperative radiographs for instrumented single-level degenerative spinal fusions: utility after intraoperative fluoroscopy

There is a paucity of literature examining the clinical yield of in-hospital postoperative radiographs for patients who have had instrumented single-level spinal fusions with intraoperative fluoroscopic guidance. Many spinal surgeons consider postoperative standing radiographs to be the appropriate standard of care, even in patients who have an uneventful postoperative course. To evaluate the additional clinical yield and cost-effectiveness of in-hospital postoperative standing radiographs for patients undergoing instrumented single-level cervical and lumbar fusions in which intraoperative fluoroscopy is used. Are postoperative standing radiographs necessary before hospital discharge? Retrospective review of 100 consecutive degenerative spinal surgical cases in which intraoperative fluoroscopic imaging was compared with immediate postoperative radiographs using a vertebral grid mapping technique. A retrospective review of 100 consecutive patients who had an instrumented single-level cervical (30) or lumbar (70) fusion for a degenerative spinal condition performed by the same surgeon using intraoperative fluoroscopy. All patients had a documented uneventful postoperative hospitalization without evidence of new postoperative neurologic finding. All patients had both anteroposterior (AP) and lateral intraoperative fluoroscopic images and same-hospitalization standing AP and lateral radiographic images, which were performed within 72 hours postoperatively. Intraoperative and postoperative images were compared by two observers independently using a vertebral grid mapping technique to locate screw position and control magnification differences. Study parameters included screw tip position grids, interbody graft position, segmental sagittal plane alignment, spondylolisthesis grade, and hospital charges for patient imaging and interpretation. Early instrumentation failure and/or screw position change was not observed in any patient. Seventy-four patients demonstrated a grid match for all screw tip positions on both true AP and lateral radiographs. Twenty-six patients had either a postoperative AP or lateral radiograph that was clinically malrotated and precluded comparison with the intraoperative true fluoroscopic images. Segmental sagittal alignment difference between intraoperative fluoroscopic and postoperative radiographic sagittal images averaged only 1.2° (range, 0-9) and was not statistically significant (paired Student t test, p=.88). Significant difference between intraoperative and immediate postoperative interbody graft position and spondylolisthesis grade was not demonstrated in any patient. Patient hospital billing charges for postoperative AP and lateral radiographic imaging with interpretation averaged $600. In patients who have a single-level instrumented fusion and a documented uneventful postoperative course, in-hospital postoperative standing AP and lateral radiographs do not appear to provide additional clinically relevant information when intraoperative fluoroscopy is properly used. Fluoroscopy also demonstrated more consistent accuracy and a potential for significant cost savings.

Long Term Results of Anterior Corpectomy and Fusion for Cervical Spondylotic Myelopathy

BackgroundResults showed good clinical outcomes of anterior corpectomy and fusion (ACCF) for patients with cervical spondylotic myelopathy (CSM) during a short term follow-up; however, studies assessing long term results are relatively scarce. In this study we intended to assess the long term clinical and radiographic outcomes, find out the factors that may affect the long term clinical outcome and evaluate the incidence of adjacent segment disease (ASD).MethodsThis is a retrospective study of 145 consecutive CSM patients on ACCF treatment with a minimum follow-up of 5 years. Clinical data were collected from medical and operative records. Patients were evaluated by using the Japanese Orthopedic Association (JOA) scoring system preoperatively and during the follow-up. X-rays results of cervical spine were obtained from all patients. Correlations between the long term clinical outcome and various factors were also analyzed.FindingsNinety-three males and fifty-two females completed the follow-up. The mean age at operation was 51.0 years, and the mean follow-up period was 102.1 months. Both postoperative sagittal segmental alignment (SSA) and the sagittal alignment of the whole cervical spine (SACS) increased significantly in terms of cervical lordosis. The mean increase of JOA was 3.8±1.3 postoperatively, and the overall recovery rate was 62.5%. Logistic regression analysis showed that preoperative duration of symptoms >12 months, high-intensity signal in spinal cord and preoperative JOA score ≤9 were important predictors of the fair recovery rate (≤50%). Repeated surgery due to ASD was performed in 7 (4.8%) cases.ConclusionsACCF with anterior plate fixation is a reliable and effective method for treating CSM in terms of JOA score and the recovery rate. The correction of cervical alignment and the repeated surgery rate for ASD are also considered to be satisfactory.

Single level cervical fusion by an anterior approach using autologous bone graft influences the adjacent levels degenerative changes: clinical and radiographic results at 10-year minimum follow-up.

Cervical degenerative pathology can produce pain and disability and, in case of failure of conservative treatment surgery is indicated. 107 patients affected by single level cervical degenerative pathology were surgically treated by Cloward procedure. On radiographs, the sagittal segmental alignment (SSA) of the affected level and sagittal alignment of the cervical spine were measured. Preoperatively, mean SSA was 0.6° and at the last follow-up 1.8°. In particular, adjacent-level degeneration occurred more frequently in Group A than in Group B. Lordotic SSA angle can be considered a protective factor against adjacent-level degeneration.

The mid-term effects of Bryan cervical disc prosthesis on sagittal alignment of overall cervical spine and the functional spinal unit

To investigate the mid-term radiological outcome of sagittal alignment of overall cervical spine and the functional spinal unit after replacement surgery with Bryan cervical disc prosthesis. Eighteen patients with cervical disc disorder were performed cervical disc replacement with 20 Bryan discs from November 2005 to May 2010, including single-level 16 cases and bi-level 2 cases. The patient consisted of 13 males and 5 females with age ranging from 38 to 59 years (average, (47 ± 6) years). Fourteen cases with overall cervical lordotic alignment and segmental lordotic alignment per-operatively (group 1) and 4 others with segmental kyphotic alignment and overall cervical kyphotic alignment per-operatively (group 2). The overall sagittal alignment (C(2-7)) and segmental sagittal alignment were measured pre-operatively, post-operatively and at final follow-up to evaluate the outcome. All cases obtained the follow-up with an average of (24 ± 5) months (range 12 to 53 months). To the mean overall cervical alignment, there were 9.9° ± 1.9° per-operatively, 12.8° ± 2.1° post-operatively and 11.6° ± 1.8° at final follow-up in group 1 and -1.8° ± 0.8° per-operatively, 7.3° ± 1.3° post-operatively and 5.0° ± 2.1° at final follow-up in group 2. There were statistical significance between per-operatively and post-operatively (t = -2.987 and -5.058, P < 0.05) and no statistical significance between post-operatively and final follow-up (P > 0.05) in both groups. To the mean segmental alignment there were 2.6° ± 0.8° per-operatively, 5.4° ± 1.0° post-operatively and 4.3° ± 0.9° at final follow-up in group 1 and -3.0° ± 0.8° per-operatively, 3.8° ± 1.3° post-operatively and 0.3° ± 2.8° at final follow-up in group 2. There were statistical significance between per-operatively and post-operatively in both groups (t = -3.829 and -4.086, P < 0.05) and between post-operatively and final follow-up in group 1 (t = 2.630, P < 0.05)but not in group 2 (P > 0.05). The Bryan cervical disc prosthesis has a good mid-term outcome for maintaining sagittal alignment of overall cervical spine and the functional spinal unit. Long-term follow-up should be needed to assess the long-term functionality of the prosthesis.

Prospective, Randomized, Double-Blind Clinical Study Evaluating the Correlation of Clinical Outcomes and Cervical Sagittal Alignment

Sagittal alignment of the cervical spine has received increased attention in the literature as an important determinant of clinical outcomes after anterior cervical diskectomy and fusion. Surgeons use parallel or lordotically fashioned grafts depending on preference or simple availability. To quantitatively assess and compare cervical sagittal alignment and clinical outcome when lordotic or parallel allografts were used for fusion. A prospective, randomized, double-blind clinical study that enrolled 122 patients was performed. The mean follow-up was 37.5 months (range, 12-54 months). The mean postoperative cervical sagittal alignment was 19° (range, -7°-36°) and 18° (range, -7°-37°) in the lordotic and parallel graft patient groups, respectively. The mean segmental sagittal alignment was 6° (range, -4°-19°) and 7° (range, -3°-19°) in the lordotic and parallel graft patient groups, respectively. There were no statistically significant differences in clinical outcome scores between the lordotic and parallel graft patient groups. However, patients who had maintained or improved segmental sagittal alignment, regardless of graft type, achieved a higher degree of improvement in Short Form-36 Physical Component Summary and Neck Disability Index scores. This was statistically significant (P < .038). The use of lordotically shaped allografts does not increase cervical/segmental sagittal alignment or improve clinical outcomes. Maintaining a consistent segmental sagittal alignment or increasing segmental lordosis was related to a higher degree of improvement in clinical outcomes.

Sagittal segmental alignment as predictor of adjacent-level degeneration after a cloward procedure.

The Cloward anterior interbody fusion is commonly performed for cervical disc herniation or spondylosis. In followup studies, various authors have noted clinically relevant adjacent-level degeneration. However, factors associated with adjacent-level degeneration are not well known. We asked whether the postoperative sagittal segmental alignment of the fused vertebrae could be used as a predictor of adjacent-level degeneration. We retrospectively studied 107 patients, aged 35 to 55 years, with one-level cervical disc disease between C4 and C7 operated on from 1985 to 1995 by discectomy and one-level anterior cervical fusion according to the Cloward procedure. In standard radiographs of the cervical spine in lateral view, the alignment of the involved intervertebral space (sagittal segmental alignment) and the sagittal alignment of the cervical spine were measured and the adjacent-level degeneration was assessed using the Kellgren and Lawrence criteria. The minimum followup was 10 years (mean, 16 years; range, 10-23 years). Preoperatively, mean sagittal segmental alignment was 0.6°±2.0° and sagittal alignment of the cervical spine was 17.0°±4.9°. At last followup, the mean sagittal segmental alignment was 1.8°±4.1° and mean sagittal alignment of the cervical spine was 19.7°±6.6°. Adjacent-level degeneration was present in 60% of cases with postoperative sagittal segmental alignment of 0° or less and in 27% of cases with postoperative sagittal segmental alignment of more than 0°. To prevent adjacent-level degeneration, we recommend proper lordotic sagittal segmental alignment when anterior interbody fusion of the cervical spine is indicated. Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Cervical disc herniation and cervical spondylosis surgically treated by Cloward procedure: a 10-year-minimum follow-up study

BackgroundCervical degenerative pathology produces pain and disability, and if conservative treatment fails, surgery is indicated. The aim of this study was to determined whether anterior decompression and interbody fusion according to Cloward is effective for treating segmental cervical degenerative pathology and whether the results are durable after a 10-year-minimum follow-up.Materials and methodsFifty-one patients affected by single-level cervical degenerative pathology between C4 and C7 were surgically treated by the Cloward procedure. Clinical evaluation was rated using the Neck Disability Index (NDI) and the visual analog scale (VAS). At last follow-up, the outcomes were rated according to Odom’s criteria. On radiographs, the sagittal segmental alignment (SSA) of the affected level and the sagittal alignment of the cervical spine (SACS) were measured.ResultsAverage NDI was 34 preoperatively and 11 at last follow-up. Average VAS was 7 preoperatively and 1 at last follow-up. According to Odom’s criteria, the outcome was considered excellent in 18 cases, good in 22, and fair in 11. Average SSA was 0.5 ± 2.1 preoperatively, 1.8 ± 3.8 at 6 months, and 1.8 ± 5.7 at last follow-up. Average SACS was 16.5 ± 4.0 preoperatively, 20.9 ± 5.8 at 6 months, and 19.9 ± 6.4 at last follow-up. Degenerative changes at the adjacent levels were observed in 18 patients (35.3%).ConclusionsThe Cloward procedure proved to be a suitable and effective technique for treating segmental cervical degenerative pathology, allowing good clinical and radiographic outcomes even at a long-term follow-up.

Use of polyetheretherketone spacer and recombinant human bone morphogenetic protein-2 in the cervical spine: a radiographic analysis

Background context Results recently reported in the literature have raised some concerns regarding the use of recombinant human bone morphogenetic protein (rhBMP-2) in the cervical spine. Purpose We undertook a radiological and clinical review of cervical fusions performed at our institution with polyetheretherketone (PEEK) interbody cage and rhBMP-2. Study design Observational study. Patient sample Perioperative clinical and radiologic data of all patients who underwent an anterior cervical discectomy and fusion using PEEK and rhBMP-2 for cervical spondylotic radiculopathy or myelopathy were collected. Outcome measures Images were examined for fusion, heterotopic ossification, end-plate resorption, subsidence, and segmental sagittal alignment. Methods All patients underwent detailed postoperative radiologic analysis using a computed tomography (CT) scan obtained at least 6 months postoperatively and plain X-rays obtained at regular intervals. Results Twenty-two patients had 38 levels fused using PEEK and varying doses of rhBMP-2. No anterior cervical swelling requiring additional procedures or longer than anticipated hospital stays occurred. Pseudoarthrosis, shown as a horizontal radiolucent fissure through the midportion of the PEEK cage on CT, occurred in four patients. Excessive bone growth into the spinal canal or foramina occurred in 26 (68%) patients but did not result in neurologic sequelae. Cystic regions in the core of the PEEK spacer were seen in most patients, with 15 levels (39%) having cysts measuring 3 mm or greater. Moderate or severe osteolysis of the end plates occurred in 57% of levels, and this led to subsidence of the construct and loss of some of the segmental sagittal alignment (ie, lordosis) that had been achieved with surgery. Conclusions The unlimited supply of PEEK spacers and rhBMP-2 and their ease of use make them attractive platforms to achieve fusion. This study has demonstrated that the fusion process using rhBMP-2 is a dynamic one, with osteolysis dominating the initial phase, leading to end-plate resorption and consequently loss of some of the disc space height and sagittal alignment that was achieved with surgery. There is a high incidence of bone growth beyond the core of the PEEK spacer and cystic regions within the cage. Given our experience, we currently reserve the use of PEEK and rhBMP-2 for use in those patients who are at greatest risk of pseudoarthrosis.

Three-level anterior cervical discectomy: radiographic and clinical results analysis.

Objective Retrospective study of radiographic and clinical results for cervical spondylo-sis patients treated with three-level anterior cervical discectomy. Methods From October 2002 to January 2007, 23 cervical spondylosis patients (including 15 males, 8 females, with the mean age of 51.4 years) un-derwent three-level anterigr cervical discectomy, iliae crest autograft fusion and titanium plate fixation. Pa-tients wore collar braces for a period of 6 to 8 weeks post surgery. Radiographic and clinic follow-up data were collected respectively. Study parameters include the JOA score and its improvement rate, results were graded from excellent to poor using the Odom criteria and post operative assessment of neck symptoms. The sagittal segmental alignment of fusion levels were measured using the Cobb method before and after surgery. Adjacent level degeneration and graft fusion rate were observed upon final follow up. Results All patients were followed up for 11-48 months, with the average of 19.8 months. The JOA score in 20 patients was 11.1±1.0 preoperatively, and 14.6±1.0 three months postoperatively. The mean JOA score improvement rate was 62%. Three patients with radiculopathy: one patient presenting with deltoid muscle weakness improved from grade 2 before surgery to grade 4 after surgery, symptoms of the other two patients were alleviated. Sur-gical results graded according to Odom criteria: 15 excellent, 4 good, 4 fair. Remnant neck symptoms inci-dence was 17.4%(4/23). Graft fusion rate was 100%. Radiograph analysis indicated preoperative mean seg-mental lordosis 3.7°, mean segmental lordosis 10.8° upon one week follow up, and segmental lordosis was 10.4° upon final follow up. No detectable adjacent level disease incidence was noted. No neurological and instrumentation-related complications occurred. Conclusion Three-level anterior cervical discectomy, iliac crest autograft fusion, and titanium plate fixation, present high fusion rates with positive clinic outcomes in the treatment of multilevel cervical spondylosis. Key words: Cervical spondylosis; Diskectomy; Spinal fusion

The Evolution of Sagittal Segmental Alignment of the Spine During Childhood

Cross-sectional. The purpose of this study is to describe the normative data of the sagittal plane on pediatric age population, and to document the evolution of sagittal alignment with growth. Having normative data about the sagittal plane is an integral part in the planning of the three-dimensional reconstruction of the spine. Segmental sagittal plane analysis on adults has been studied thoroughly; however, there are inadequate data on children. A total of 151 children (72 girls, 79 boys) without musculoskeletal abnormality between the ages of 3 to 15 years were studied with the 36-inch standing lateral radiograph with the arms flexed at 30 degrees . There were a minimum of 10 children, at least 4 of them from one sex, in each age group. Variables measured on the radiograms were as follows: segmental angulations from T1-T2 to L5-S1, angles of global kyphosis (T1-T12) and lordosis (L1-S1), segmental angulations of T2-T5, T10-T12, T10-L2, and L4-S1 levels, T1 and L1 offsets in millimeters, location of thoracic and lumbar apexes, and spinopelvic alignment measurements (angles of alpha and beta, sagittal vertebral axis, and sacropelvic translation). For statistical analysis, the children were grouped in terms of ages: Group I (3-6 years of age), Group II (7-9 years of age), Group III (10-12 years of age), and Group IV (13-15 years of age). One-way analysis of variance showed significant differences between the following parameters among groups: segmental angulations of T1-T2 (P = 0.015), T10-L2 (P = 0.014), L4-S1 (P = 0.001), global kyphosis angle (P = 0.005), global lordosis angle (P = 0.000), thoracic apex (P = 0.007), T1 offset (P = 0.000), sagittal vertebral axis (P = 0.004), and beta angle (P = 0.000). As sagittal vertebral axis increases, there is found to be a higher L1 offset and lower thoracic apex, both of which result in leaning forward. With growing, total thoracic kyphosis and total lumbar lordosis particularly due to lower 2 motion segments were found to be increased, while thoracic apex moved upwards, T1 offset increased, and L1 offset decreased. Older children stood with a more negative SVA, and sacral inclination increased. Sagittal spinal alignment is found to be changing as a child grows. There is a statistically significant difference among different age groups, especially at cervicothoracic, thoracolumbar, and lumbosacral junctions. The position of the sacrum (inclination and translation), and spatial orientation, as well as the global magnitude of thoracic kyphosis, and lumbar lordosis changes with growth. These findings should be taken into consideration for the young patients who require spinal instrumentation. The question "whether sagittal alignment should be restored according to the normative data for the child's age or to the normative data for the adulthood" remains to be answered.

Long-Term Flexion-Extension Range of Motion of the Prodisc Total Disc Replacement

The rationale for total disc replacement is avoidance of the junctional degeneration seen after arthrodesis by preservation of segmental motion. To justify the use of disc prostheses, it is essential to document maintained range of motion (ROM) and sagittal alignment at long-term follow-up. This is a retrospective radiographic study of 42 patients who had placement of 58 first-generation Prodisc prostheses at a mean follow-up of 8.7 years. Flexion-extension ROM was measured by Cobb's method. Junctional levels were evaluated for junctional degeneration. Pre- and postoperative global and segmental lordosis were measured. Prognostic patient factors predicting ROM of <2 degrees were evaluated. We observed ROM of at least 2 degrees in 66% of Prodisc prostheses at 8.7-year follow-up, although ROM was less than that reported in asymptomatic normal individuals. Mean ROM for disc prostheses with motion was 7.5 degrees at L3-L4, 6.2 degrees at L4-L5, and 4.1 degrees at L5-S1. Mean ROM for all prostheses was 3.8 degrees. The incidence of radiographic junctional degeneration was 24%, although no patients required surgery for symptomatic junctional degeneration. Mean ROM of prostheses below a degenerated junctional disc was 1.6 degrees compared with 4.7 degrees below a normal junctional disc (P < 0.035). Females were 3.5 times more likely to have ROM of <2 degrees. This is the longest published follow-up study of a lumbar disc replacement. The data show that ROM is preserved at long-term follow-up in the majority of patients. Global and segmental sagittal alignment improve after surgery. Furthermore, there is an association between ROM of disc prostheses and the development of junctional degeneration.

Reciprocal angulation of vertebral bodies in the sagittal plane in an asymptomatic Greek population.

A prospective study conducted on several roentgenographic parameters of the standing sagittal profile of the spine in an asymptomatic Greek population. To perform segmental analysis of the sagittal plane alignment of the normal thoracic, lumbar, and lumbosacral spines and to compare the findings with those derived from similar populations. Until recently, little attention has been paid to the sagittal segmental alignment of the spine, and there are only a few studies (in French and American populations) in which radiographic analysis of sagittal spinal alignment is investigated. Ninety-nine consecutive asymptomatic Greek volunteers (38 men, 61 women), an average age of 52.7 +/- 15 years old (range, 20-79 years), were included in this prospective study, on the basis of several inclusion criteria. These volunteers were divided into six distinct age groups. The radiologic parameters, which were measured (by Cobb's method) on the lateral standing roentgenograms of the whole spine were: thoracic kyphosis (T4-T12), lumbar lordosis (L1-L5), total lumbar lordosis (T12-S1), distal lumbar lordosis (L4-S1), sacral inclination (measured from the line drawn parallel along the back of the proximal sacrum and the vertical line), pelvic tilting, vertebral body inclination, and relative segmental inclination between pairs of adjacent vertebrae. Thoracic kyphosis and lumbar lordosis (T12-S1, L1-L5) were not gender related. Thoracic kyphosis increased with age (P < 0.001), the lumbar spine (L1-L5) gradually became less lordotic as the thoracic kyphosis increased (P < 0.003), and total lumbar lordosis was not age related. Sacral inclination correlated strongly with both thoracic kyphosis (P < 0.002) and L1-L5 lordosis (P < 0.001). Pelvic tilting correlated strongly with L1-L5 lordosis (P < 0.0075), but did not correlate with thoracic kyphosis and age. Vertebral body inclination showed a narrow variability in T6-T12 and in L4 and a wide variability in T4, T5, L1-L3, and S1. Distal lumbar lordosis represents the 68.6% of the total lumbar lordosis. In the results of this study, a reliable table of reference for roentgenographic parameters in the sagittal plane of the spine was established in an asymptomatic Greek population. The parameters are similar to those used in previous studies. Thus, these data should be considered in preoperative planning and postoperative evaluation of achieved correction during restoration procedures of the spine in the sagittal plane.

Radiographic standing cervical segmental alignment in adult volunteers without neck symptoms.

A radiographic evaluation of standing cervical and global sagittal alignment in 100 adult volunteers with no neck or radicular arm symptoms was undertaken. To document and define cervical standing lateral alignment and balance in a volunteer population without cervical problems. Minimal data exist on cervical segmental sagittal alignment distributions in stance. Radiographic measures of spinal alignment were collected and statistically analyzed. Data were categorized into two age- and sex-matched groups. Group 1 had no cervical or lumbar symptoms. Group 2 had no cervical symptoms, but had lumbar symptoms. Mean total and segmental cervical alignment distributions were not statistically different between groups. Mean total cervical lordosis in stance for the entire group was -40.0 +/- 9.7 degrees. Thoracic and lumbar alignment were within previously reported measures and not statistically different between groups. Plumb line markers at C7 and sacral reference points were not statistically different between groups. Pearson correlations revealed that cervical sagittal plane alignment vaired inversely with thoracic alignment. Independent orthopedists noted cervical osteoarthritis was present in 17% of each group of volunteers with substantial kappa agreement (0.73) between observers. Intraobserver and interobserver reliability of sagittal alignment measures of 30 randomly remeasured radiographs revealed strong correlation between observations. No differences in total cervical lordosis were noted between cervical asymptomatic volunteers with or without low back pain. Most cervical lordosis occurred at the C1-C2 level in stance, whereas only 6 degrees (15%) occurred at the lowest three cervical levels (C4-C7). Changes in cervical lordosis correlated inversely with changes in thoracic alignment.