Pedicle morphology of the thoracic spine in preadolescent idiopathic scoliosis: magnetic resonance supported analysis

Although several studies have been reported on the adult vertebral pedicle morphology, little is known about immature thoracic pedicles in patients with idiopathic scoliosis. A total of 310 pedicles (155 vertebrae) from T1 to T12 in 10–14 years age group were analyzed with the use of magnetic resonance imaging and digital measurement program in 13 patients with right-sided thoracic idiopathic scoliosis. Each pedicle was measured in the axial and sagittal planes including transverse and sagittal pedicle width and angles, chord length, interpedicular distance and epidural space width on convex and concave sides of the curve. The smallest transverse pedicle widths were in the periapical region and the largest were in the caudal region. No statistically significant difference in transverse pedicle widths was detected between the convex and concave sides. The transverse pedicle angle measured 15.56° at T1 and decreased to 6.32° at T12. Chord length increased gradually from the cephalad part of the thoracic spine to the caudad part as the shortest length was seen at T1 convex level with a mean of 30.45 mm and the largest length was seen at T12 concave level with a mean of 41.73 mm. The width of epidural space on the concave side was significantly smaller than that on the convex side in most levels of the curve. Based on the anatomic measurements, it may be reasonable to consider thoracic pedicle screws in preadolescent idiopathic scoliosis.     

What is the Difference in Morphologic Features of the Thoracic Pedicle Between Patients With Adolescent Idiopathic Scoliosis and Healthy Subjects? A CT-based Case-control Study

Background

Describing the morphologic features of the thoracic pedicle in patients with adolescent idiopathic scoliosis is necessary for placement of pedicle screws. Previous studies showed inadequate reliability owing to small sample size and heterogeneity of the patients surveyed.

Questions/Purposes

To use CT scans (1) to describe the morphologic features of 2718 thoracic pedicles from 60 female patients with Lenke Type 1 adolescent idiopathic scoliosis and 60 age-, sex-, and height-matched controls; and (2) to classify the pedicles in three types based on pedicle width and analyze the distribution of each type.

Methods

A total of 2718 pedicles from 60 female patients with Lenke Type 1 adolescent idiopathic scoliosis and 60 matched female controls were analyzed via CT. All patients surveyed were diagnosed with adolescent idiopathic scoliosis, Lenke Type 1, at the First Affiliated Hospital of Sun Yat-sen University, and all underwent pedicle screw fixation between January 2008 and December 2013 with preoperative radiographs and CT images on file. We routinely obtained CT scans before these procedures; all patients who underwent surgery during that period had CT scans, and all were available for analysis here. Control subjects had CT scans for other clinical indications and had no abnormal findings of the spine. The control subjects were chosen to match patients in terms of age (15 ± 2.6 years versus 15 ± 2.6 years) and sex. Height of the two groups also was matched (154 ± 9 cm versus 155 ± 10 cm; mean difference, −1.06 cm; 95% CI, −1.24 to −0.81 cm; p < 0.001). Pedicle width and length were measured from T1 to T12. The thoracic spine was classified in four regions: apical vertebra in the structural curve (AV-SC), nonapical vertebra in the structural curve (NAV-SC), apical vertebra in the nonstructural curve (AV-NSC), and nonapical vertebra in the nonstructural curve (NAV-NSC). Pedicles were classified in three types: pedicle width less than 2 mm as Type I, 2 mm to 4 mm as Type II, and greater than 4 mm as Type III. Types I and II were defined as dysplastic pedicles. Paired t test, independent samples t test, one-way ANOVA, followed by Bonferroni’s post hoc test and chi-square or Fisher’s exact tests were used for statistical comparisons between patients and controls, as appropriate.

Results

No difference was found between pedicle width on the convex side (PWv) and in controls (PWn), but pedicle width on the concave side (PWc) (4.99 ± 1.87 mm) was found to be narrower than PWv (6 ± 1.66 mm) and PWn (6 ± 1.45 mm). The variation degree of pedicle width (VDPW) was greatest in the AV-SC region (34% ± 37%), in comparison to AV-NSC (20% ± 25%) (mean difference, 14%; 95% CI, 1.15%–27%; p = 0.025), NAV-SC (17% ± 30%) (mean difference, 17%; 95% CI, 7%–27%; p < 0.001), and NAV-NSC (11% ± 24%) (mean difference, 24%; 95% CI, 13%–34%; p < 0.001). Dysplastic pedicles appeared more in patients with adolescent idiopathic scoliosis (22%; 293 of 1322) compared with controls (13%; 178 of 1396) (odds ratio [OR] = 0.51; 95% CI, 0.42–0.63; p < 0.001). In patients with adolescent idiopathic scoliosis, they commonly occurred on the concave side 34% (228 of 661) and on the AV-SC region (32%; 43 of 136).

Conclusions

Pedicle width on the concave side was narrower than pedicle width on the convex side and pedicle width in healthy control subjects. The apical vertebra in the structural curve was the most variegated region of the curve with the highest prevalence of dysplastic pedicles.

Clinical Relevance

Our study can help surgeons perform preoperative assessments in females with adolescent idiopathic scoliosis, and with preoperative and intraoperative management for difficult pedicle screw placement. In particular, our results suggest that surgeons should exercise increased vigilance when selecting pedicle screw dimensions, especially in the concave aspect of the mid-thoracic curve, to avoid cortical breeches. Future studies should evaluate other Lenke types of adolescent idiopathic scoliosis, and males with adolescent idiopathic scoliosis.

     

Analysis of vertebral morphology in idiopathic scoliosis with use of magnetic resonance imaging and multiplanar reconstruction

BACKGROUND: Several studies have provided data on the vertebral morphology of normal spines, but there is a paucity of data on the vertebral morphology in patients with idiopathic scoliosis. METHODS: The morphology of the pedicles and bodies of 307 vertebrae as well as the distance between the pedicles and the dural sac (the epidural space) in twenty-six patients with right-sided thoracic idiopathic scoliosis were analyzed with use of magnetic resonance imaging and multiplanar reconstruction. RESULTS: A distinct vertebral asymmetry was found at the apical region of the thoracic curves, with significantly thinner pedicles on the concave side than on the convex side (p < 0.05). The degree of intravertebral deformity diminished farther away from the apex, with vertebral symmetry restored at the neutral level. In the thoracic spine, the transverse endosteal width of the apical pedicles measured between 2.3 mm and 3.2 mm on the concave side and between 3.9 mm and 4.4 mm on the convex side (p < 0.05). In the lumbar spine, the pedicle width measured between 4.6 mm at the cephalad part of the curve and 7.9 mm at the caudad part of the curve. The chord length and the pedicle length gradually increased from 34 mm and 18 mm, respectively, at the fourth thoracic vertebra to 51 mm and 25 mm, respectively, at the third lumbar vertebra. The transverse pedicle angle measured 15 in the cephalad aspect of the thoracic spine, decreased to 7 at the twelfth thoracic vertebra, and increased again to 16 at the fourth lumbar vertebra. The width of the epidural space was <1 mm at the thoracic apical vertebral levels and averaged 1 mm at the lumbar apical vertebral levels on the concave side, whereas it was between 3 mm and 5 mm on the convex side (p < 0.05). CONCLUSION: Idiopathic scoliosis is associated with distinctive intravertebral deformity, with smaller pedicles on the concave side and a shift of the dural sac toward the concavity.     

Influence of implant rod curvature on sagittal correction of scoliosis deformity

Background contextDeformation of in vivo–implanted rods could alter the scoliosis sagittal correction. To our knowledge, no previous authors have investigated the influence of implanted-rod deformation on the sagittal deformity correction during scoliosis surgery.PurposeTo analyze the changes of the implant rod's angle of curvature during surgery and establish its influence on sagittal correction of scoliosis deformity.Study designA retrospective analysis of the preoperative and postoperative implant rod geometry and angle of curvature was conducted.Patient sampleTwenty adolescent idiopathic scoliosis patients underwent surgery. Average age at the time of operation was 14 years.Outcome measuresThe preoperative and postoperative implant rod angle of curvature expressed in degrees was obtained for each patient.MethodsTwo implant rods were attached to the concave and convex side of the spinal deformity. The preoperative implant rod geometry was measured before surgical implantation. The postoperative implant rod geometry after surgery was measured by computed tomography. The implant rod angle of curvature at the sagittal plane was obtained from the implant rod geometry. The angle of curvature between the implant rod extreme ends was measured before implantation and after surgery. The sagittal curvature between the corresponding spinal levels of healthy adolescents obtained by previous studies was compared with the implant rod angle of curvature to evaluate the sagittal curve correction. The difference between the postoperative implant rod angle of curvature and normal spine sagittal curvature of the corresponding instrumented level was used to evaluate over or under correction of the sagittal deformity.ResultsThe implant rods at the concave side of deformity of all patients were significantly deformed after surgery. The average degree of rod deformation Δθ at the concave and convex sides was 15.8° and 1.6°, respectively. The average preoperative and postoperative implant rod angle of curvature at the concave side was 33.6° and 17.8°, respectively. The average preoperative and postoperative implant rod angle of curvature at the convex side was 25.5° and 23.9°, respectively. A significant relationship was found between the degree of rod deformation and preoperative implant rod angle of curvature (r=0.60, p<.005). The implant rods at the convex side of all patients did not have significant deformation. The results indicate that the postoperative sagittal outcome could be predicted from the initial rod shape.ConclusionsChanges in implant rod angle of curvature may lead to over- or undercorrection of the sagittal curve. Rod deformation at the concave side suggests that corrective forces acting on that side are greater than the convex side.     

单侧椎弓根钉内固定建立新型山羊脊柱侧凸模型的实验研究

目的探讨未成年山羊脊柱单侧椎弓根钉内固定并对侧肋骨切除建立新型脊柱侧凸模型的可行性。方法实验对象为14只雌性山羊,年龄5~8周,体重6~8kg。在全麻下进行模型制作,T5~L2做右旁正中皮肤切口,分别于脊柱左侧T6,7和T12、L1部位置入特制椎弓根螺钉,经皮下及肌肉下插入1枚不锈钢棒置入螺钉槽口内,远近端螺钉之间适当加压使脊柱向右凸;然后于脊柱右侧分别切除第7~12肋骨2~3cm左右。术后即刻及每4周拍摄正侧位X线片,观察山羊在生长过程中脊柱弯曲的变化。结果1只小羊因麻醉过量,术中死亡;另1只因术后感染而导致内固定失败,观察终止。其余12只小羊中,11只小羊X线片显示右侧侧凸畸形,并且Cobb角随时间延长而增大。只有1只羊术后Cobb角没有进展。术后即刻Cobb角平均为29.0°(23.0°~38.5°),8~10周后Cobb角增至平均43.0°(36.0°~58.0°),平均进展14.0°。术后8周(1只为10周)时获取脊柱标本,去除内固定后发现所有弯曲均为结构性。从脊椎的旋转和外观方面来看,均与特发性脊柱侧凸畸形相似。结论单侧椎弓根钉内固定是一种比较可靠的建立脊柱侧凸模型的方法,模型与特发性脊柱侧凸相似,适用于脊柱侧凸畸形的实验研究。     

Morphometric analysis using multiplanar reconstructed CT of the lumbar pedicle in patients with degenerative lumbar scoliosis characterized by a Cobb angle of 30° or greater

Object Although the anatomy of the thoracic pedicle in adolescent idiopathic scoliosis is well known, that of the lumbar pedicle in degenerative lumbar scoliosis is not. The morphometric differences between the pedicles on the concave and convex sides can result in an increased risk of malpositioned pedicle screws. The purpose of this study was to analyze the lumbar pedicle morphology in degenerative lumbar scoliosis using multiplanar reconstructed CT. Methods The study group comprised 16 consecutive patients (1 man and 15 women, mean age 70.9 ± 4.5 years) with degenerative lumbar scoliosis characterized by a Cobb angle of at least 30° who underwent preoperative helical CT scans. The CT data in DICOM format were reconstructed, and the following parameters were measured for each pedicle inside the curves: the inner cortical transverse pedicle width (TPWi) and outer cortical transverse pedicle width (TPWo) and axial angle, all on an axial plane, and the inner cortical minimum pedicle diameter (MPDi) and outer cortical minimum pedicle diameter (MPDo) and cephalocaudal inclination of the pedicle, all on the plane perpendicular to the pedicle axis. The cortical thickness and cortical ratio of the pedicles on the axial plane and the plane perpendicular to the pedicle axis were calculated. Data were obtained for a total of 124 pedicles; L-1, 26 pedicles in 13 patients; L-2, 32 pedicles in 16 patients; L-3, 32 pedicles in 16 patients; L-4, 28 pedicles in 14 patients; and L-5, 6 pedicles in 3 patients. Results Among the target vertebrae, the TPWi, MPDi, and MPDo were significantly smaller and the axial angle was significantly larger on the concave side than on the convex side (TPWi, 6.37 vs 6.70 mm, p < 0.01; MPDi, 5.15 vs 5.67 mm, p < 0.01; MPDo, 7.91 vs 8.37 mm, p < 0.05; axial angle, 11.79° vs 10.56°, p < 0.01). The cortical ratio of the pedicles was larger on the concave side than on the convex side (on the axial plane, 0.29 vs 0.26, p < 0.05; on the plane perpendicular to the pedicle axis, 0.36 vs 0.32, p < 0.01). These differences were most evident at L-4. Conclusions This study demonstrated lumbar pedicle asymmetry in degenerative lumbar scoliosis. The authors speculate that these asymmetrical changes were attributed to the remodeling caused by axial load imbalance and the limited space available for pedicles on the concave side. On the concave side, because of the narrower pedicle diameter and larger axial angle, surgeons should carefully determine screw size and direction when inserting pedicle screws to prevent possible pedicle wall breakage and neural damage.     

The biomechanical consequences of rod reduction on pedicle screws: should it be avoided?

Background contextRod contouring is frequently required to allow for appropriate alignment of pedicle screw-rod constructs. When residual mismatch is still present, a rod persuasion device is often used to achieve further rod reduction. Despite its popularity and widespread use, the biomechanical consequences of this technique have not been evaluated.PurposeTo evaluate the biomechanical fixation strength of pedicle screws after attempted reduction of a rod-pedicle screw mismatch using a rod persuasion device.MethodsFifteen 3-level, human cadaveric thoracic specimens were prepared and scanned for bone mineral density. Osteoporotic (n=6) and normal (n=9) specimens were instrumented with 5.0-mm–diameter pedicle screws; for each pair of comparison level tested, the bilateral screws were equal in length, and the screw length was determined by the thoracic level and size of the vertebra (35 to 45 mm). Titanium 5.5-mm rods were contoured and secured to the pedicle screws at the proximal and distal levels. For the middle segment, the rod on the right side was intentionally contoured to create a 5-mm residual gap between the inner bushing of the pedicle screw and the rod. A rod persuasion device was then used to engage the setscrew. The left side served as a control with perfect screw/rod alignment. After 30 minutes, constructs were disassembled and vertebrae individually potted. The implants were pulled in-line with the screw axis with peak pullout strength (POS) measured in Newton (N). For the proximal and distal segments, pedicle screws on the right side were taken out and reinserted through the same trajectory to simulate screw depth adjustment as an alternative to rod reduction.ResultsPedicle screws reduced to the rod generated a 48% lower mean POS (495±379 N) relative to the controls (954±237 N) (p<.05) and significantly decreased work energy to failure (p<.05). Nearly half (n=7) of the pedicle screws had failed during the reduction attempt with visible pullout of the screw. After reduction, decreased POS was observed in both normal (p<.05) and osteoporotic (p<.05) bone. Back out and reinsertion of the screw resulted in no significant difference in mean POS, stiffness, and work energy to failure (p>.05).ConclusionsIn circumstances where a rod is not fully seated within the pedicle screw, the use of a rod persuasion device decreases the overall POS and work energy to failure of the screw or results in outright failure. Further rod contouring or correction of pedicle screw depth of insertion may be warranted to allow for appropriate alignment of the longitudinal rods.     

Safety and accuracy of robot-assisted placement of pedicle screws compared to conventional free-hand technique: a systematic review and meta-analysis

BACKGROUND CONTEXTThe introduction and integration of robot technology into modern spine surgery provides surgeons with millimeter accuracy for pedicle screw placement. Coupled with computer-based navigation platforms, robot-assisted spine surgery utilizes augmented reality to potentially improve the safety profile of instrumentation.PURPOSEIn this study, the authors seek to determine the safety and efficacy of robotic-assisted pedicle screw placement compared to conventional free-hand (FH) technique.STUDY DESIGN/SETTINGWe conducted a systematic review of the electronic databases using different MeSH terms from 1980 to 2020.OUTCOME MEASURESThe present study measures pedicle screw accuracy, complication rates, proximal-facet joint violation, intraoperative radiation time, radiation dosage, and length of surgery.RESULTSA total of 1,525 patients (7,379 pedicle screws) from 19 studies with 777 patients (51.0% with 3,684 pedicle screws) in the robotic-assisted group were included. Perfect pedicle screw accuracy, as categorized by Gerztbein-Robbin Grade A, was significantly superior with robotic-assisted surgery compared to FH-technique (Odds ratio [OR]: 1.68, 95% confidence interval [CI]: 1.20–2.35; p=.003). Similarly, clinically acceptable pedicle screw accuracy (Grade A+B) was significantly higher with robotic-assisted surgery versus FH-technique (OR: 1.54, 95% CI: 1.01–2.37; p=.05). Furthermore, the complication rates and proximal-facet joint violation were 69% (OR: 0.31, 95% CI: 0.20–0.48; p<.00001) and 92% less likely (OR: 0.08, 95% CI: 0.03–0.20; p<.00001) with robotic-assisted surgery versus FH-group. Robotic-assisted pedicle screw implantation significantly reduced intraoperative radiation time (MD: ?5.30, 95% CI: ?6.83–3.76; p<.00001) and radiation dosage (MD: ?3.70, 95% CI: ?4.80–2.60; p<.00001) compared to the conventional FH-group. However, the length of surgery was significantly higher with robotic-assisted surgery (MD: 22.70, 95% CI: 6.57–38.83; p=.006) compared to the FH-group.CONCLUSIONThis meta-analysis corroborates the accuracy of robot-assisted pedicle screw placement.     

特发性脊柱侧弯椎旁肌改变与手术治疗相关性的研究

目的　探讨特发性脊柱侧弯椎旁肌病理改变与脊柱畸形的因果关系。方法　对其术前、术后病人取标本进行组织化学及超微结构的研究。结果　术后Cobb′s角小于 5 0°的患者椎旁肌基本正常、双侧肌力平衡 ;而Cobb′s角仍大于 5 0°者椎旁肌病理改变与术前病人相似、双侧肌力不平衡 ,凸侧明显大于凹侧。结论　特发性脊柱侧弯椎旁肌病变是继发的 ,早期诊断、早期治疗有利于终止椎旁肌的继发性病理改变 ,使其得以最大限度的恢复     

Analysis of hip dysplasia and spinopelvic alignment in cerebral palsy

Background contextKnowledge of sagittal spinopelvic parameters and hip dysplasia is important in cerebral palsy (CP) patients because these parameters differ from those found in the general population and can be related to symptoms.PurposeThe purpose of this study was to analyze sagittal spinopelvic alignment and determine its relation to hip dysplasia in CP patients.Study designRadiological analysis was conducted on patients with CP.Patient sampleFifty-four patients with CP and 24 normal controls were included in this study.Outcome measuresParticipants underwent radiographs of the whole spine.MethodsThe patient and control groups comprised 54 CP patients and 24 volunteers, respectively. All underwent lateral radiography of the whole spine and hip joint anteroposterior radiography. The radiographic parameters examined were sacral slope, pelvic tilt, pelvic incidence, S1 overhang, thoracic kyphosis, thoracolumbar kyphosis, lumbar lordosis, sagittal balance, center edge angle, acetabular angle, and migration index. Statistical analysis was performed to identify significant differences and correlations between the two groups.ResultsSacral slope, thoracolumbar kyphosis, lumbar lordosis, sagittal balance, acetabular angle, and migration index were significantly higher in CP patients, whereas pelvic tilt, S1 overhang, and center edge angle were significantly lower (p<.05). Correlation analysis revealed that pelvic incidence, sacral slope, pelvic tilt, and S1 overhang were related to each other and that thoracolumbar kyphosis was related to the thoracic kyphosis and lumbar lordosis (p<.05). For spinal and pelvic parameters, lumbar lordosis was related to sacral slope, pelvic incidence, pelvic tilt, and S1 overhang; for hip dysplasia parameters, center edge angle and acetabular angle were found to be interrelated (p<.05). Regarding symptoms, pelvic tilt, S1 overhang, and thoracolumbar kyphosis were found to be correlated with symptom severity in patients. However, no hip dysplasia parameters were found to be related to hip or spinal symptoms.ConclusionsThis study found significant differences between CP patients and normal controls in terms of spinopelvic alignment and hip dysplasia. Furthermore, relationships were found between the sagittal spinopelvic parameters and hip dysplasia, and correlations were found between sagittal spinopelvic parameters and pain.     

Differences in treatments and outcomes for idiopathic scoliosis patients treated in the United States from 1998 to 2007: impact of socioeconomic variables and ethnicity

Background contextScoliosis is a significant cause of disability and health-care resource utilization in the United States.PurposeOur aim was to evaluate potential disparities in the selection of treatments and outcomes for idiopathic scoliosis patients on a national level. To date, only one study has examined inpatient complications, discharge disposition, and mortality with respect to scoliosis treatment on a national scale.Study design/settingRetrospective review of cases having a primary diagnosis of idiopathic scoliosis using the nationwide inpatient sample (NIS) administrative data from 1998 to 2007.Patient sampleThe NIS data were queried to identify patients with a primary diagnosis of idiopathic scoliosis (International Classification of Diseases, Ninth Revision [ICD-9] diagnosis code: 737.30) admitted routinely. Surgically treated patients were identified as those patients who underwent a spinal fusion (ICD-9-Clinical Modification code: 81.08) as a principal procedure.Outcome measuresRates of surgical versus nonsurgical treatments were measured as were inhospital complications and mortality rates.MethodsNo external funding was received for this work. Univariate and multivariate analyses evaluated race, sex, socioeconomic factors, and hospital characteristics as predictors of surgical versus nonsurgical treatments, as well as inhospital complications and mortality rates.ResultsThe study analyzed 9,077 surgically and 1,098 nonsurgically treated patients with idiopathic scoliosis. Univariate analysis showed both patient- and hospital-level variables as strongly associated with surgical versus nonsurgical treatments and outcomes. Multivariate analysis revealed that Caucasians and private insurance patients were more likely to undergo surgical treatment (p<.05) even when controlling for comorbidities. Additionally, Caucasians had a reduced risk of nonroutine discharge compared with non-Caucasians (p=.03). Large hospitals had higher surgery rates (p=.08) than small- or medium-sized facilities and a lower risk of mortality (p=.04). Caucasians (65.1%) were more commonly admitted to large teaching hospitals than African American (59.8%) or Hispanic (41.8%) patients.ConclusionsDifferences were found in the selection of surgical versus nonsurgical treatments, as well as inhospital morbidity for hospitalized idiopathic scoliosis patients based on ethnic and socioeconomic variables. This may in part be because of differences in access to the resources of large teaching hospitals for different ethnic and socioeconomic groups or variability in severity of scoliosis among these groups that was not captured in this database.     

Feasibility and biomechanical performance of a novel transdiscal screw system for one level in non-spondylolisthetic lumbar fusion: an in vitro investigation

Background contextThe bilateral pedicle screw system (BPSS) is currently the “gold standard” fusion technique for spinal instability. A new stabilization system that provides the same level of stability through a less invasive procedure will have a high impact on clinical practice. A new transdiscal screw system is investigated as a promising minimally invasive device.PurposeTo evaluate the feasibility of a novel transdiscal screw in spinal fixation as an alternative to BPSS, with and without an interbody cage, in non-spondylolisthesis cases.Study designAn in vitro biomechanical study in lumbar cadaveric spines.MethodsTwelve lumbar cadaveric segments (L4–S1) were tested under flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Six treatments were simulated as follows: (1) intact, (2) bilateral facetectomy at L4–L5, (3) transdiscal screw system, (4) BPSS, (5) BPSS with transforaminal lumbar interbody cage, and (6) transdiscal screws with transforaminal interbody cage. Specimens were randomly divided into two testing groups: Group 1 (n=6) was tested under the first five conditions, in the order presented, whereas Group 2 (n=6) was tested under the first, second, third, fourth, and sixth conditions, with the fourth condition preceding the third. Range of motion (ROM) and neutral zone stiffness (NZS) were estimated and normalized with respect to the intact condition to explore statistical differences among treatments using non-parametric approaches.ResultsSignificant differences in FE ROM were observed in the pedicle screws-cage condition with respect to the facetectomy (p<.01), the pedicle screw (p=.03), and the transdiscal screw (p<.02) conditions. All fixation constructs significantly restricted LB and AR ROM (p<.01) with respect to facetectomy. In terms of stiffness, the pedicle screw and the transdiscal screw systems increased (p<.01) LB and AR NZS with respect to facetectomy. The pedicle screws-cage condition significantly increased flexion and extension stiffness with respect to all other conditions (p<.05). However, LB NZS for the pedicle screws-cage and the transdiscal screws-cage condition could not be explored due to a testing order bias effect. There was not enough evidence to state any difference between the pedicle and transdiscal screw conditions in terms of ROM or NZS.ConclusionsTransdiscal and pedicle screw systems showed comparable in vitro biomechanical performance in the immediate stabilization of a complete bilateral facetectomy. The pedicle screws-cage condition was the most stable in FE motion; however, comparison with respect to the transdiscal screws-cage condition could not be investigated.     

A comparison of the microarchitectural bone adaptations of the concave and convex thoracic spinal facets in idiopathic scoliosis

BACKGROUND: A limited number of studies have assessed the changes in bone microarchitecture in spinal facets with use of light microscopy but not with use of electron microscopy techniques. The purpose of this study was to analyze the facets in patients with scoliosis to determine whether there are differences in the bone microarchitecture of contralateral facets at the same anatomic level. METHODS: In eight patients undergoing posterior spinal arthrodesis for the treatment of idiopathic scoliosis, biopsy specimens of facet pairs at matched anatomic levels were obtained from three locations: (1). the curve apex, (2). one level cephalad to the apex, and (3). one level caudad to the apex. The facets were analyzed for cortical bone porosity and thickness with use of scanning electron microscopy and National Institutes of Health imaging software. The concave and convex facets were compared with use of a paired t test. RESULTS: The mean porosity (and standard deviation) for the concave and convex facets was 16.5% +/- 5.8% and 24.1% +/- 6.2%, respectively. Those on the convex side were significantly more porous than those on the concave side (p 相似文献   

青少年特发性胸椎侧凸患者胸椎椎弓根横径的分型及其临床意义

目的 探讨胸椎椎弓根横径的测量及分型在青少年特发性胸椎侧凸患者治疗中的临床意义.方法 对2008年10月至2009年7月收治的30例青少年特发性胸椎侧凸患者(侧凸组)和2008年8月至2009年7月于本院就诊的20例年龄匹配的非侧凸青少年患者(对照组)采用螺旋CT行胸椎连续扫描,在图像编档和通信系统(PACS)上逐层阅片,选择胸椎椎弓根显示最清楚的层面对椎弓根横径进行测量,并根据测量结果将其分为4型.分别对侧凸组凹凸侧和对照组左右侧椎弓根横径进行对比,并对侧凸组与对照组椎弓根分型的构成比进行分析.结果 两组患者胸椎椎弓根横径T1～4逐渐减少,T5～12逐渐增加.对照组同节段双侧胸椎椎弓根横径差异无统计学意义(P>0.05).侧凸组顶椎区凹侧的椎弓根横径明显小于凸侧,差异有统计学意义(P<0.05).侧凸组中4型椎弓根的比例明显高于对照组,1型椎弓根的比例低于对照组,差异均有统计学意义(P<0.05).结论 青少年特发性胸椎侧凸患者胸椎椎弓根横径常较小,术前应根据CT胸椎椎弓根形态制定置钉策略,以减少经胸椎椎弓根置入螺钉的并发症的发生.     

Digital measurement and correlation analysis of coronal and sagittal anatomic parameters in the radiographs of adolescent patients with idiopathic scoliosis

Objective

To use digital software to measure the morphologic and anatomic parameters of adolescent idiopathic scoliosis (AIS). Differences and correlations among different parameters were compared to provide an anatomic basis for the selection of treatment methods and preoperative evaluation of AIS.

Methods

Spinal radiographs were taken from 300 boys and girls (age, 10–18 years) suffering from idiopathic scoliosis in four grade-A hospitals in Inner Mongolia. After screening, 120 cases with complete imaging data were assessed. Imaging data were transferred to a work station (Dr Wise™). The anatomic indices of the Cobb Angle, CVA, AVT, TS, CA, CPT, CSI, FPT, CCA, TK, LL, SS, PT, and PI were measured.

Results

There were significant differences in AVT between different grades and types of scoliosis (F = 34.079, P = 0.000; χ² = 23.379, P = 0.000). AVT was a protective factor, and the smaller the AVT, the less severe was the scoliosis. Compared with adolescents with mild or moderate scoliosis, the Cobb angle of adolescents with severe scoliosis was negatively correlated with CCA, LL, and SS (r =  − 0.641, p < 0.05; r =  − 0.695, p < 0.01; r =  − 0.814, p < 0.01).

Conclusions

Some of the anatomic parameters in the coronal and sagittal planes of adolescents with idiopathic scoliosis were significantly different according to the severity and type of scoliosis. Significant correlations were found between more anatomic indices in adolescents with severe scoliosis than in adolescents suffering from mild or moderate scoliosis.

     

脊柱侧凸上,下终椎和顶椎椎骨旋转的研究

对25例特发性脊柱侧凸患者采用侧卧位CT扫描正位定像法，测量上终推、顶推和下终椎椎骨旋转角度与Cobb’s角的关系、棘突轴心线与两侧椎弓根轴心线所夹角的关系、椎骨旋转与棘突移位分级的关系。结果显示，上终推椎体旋转角度与Cobb’s角无相关性（P＞0．2）；顶推和下终推与Cobb’s角均有相关性（P＜0.01）；上终椎、顶推和下终难的凹侧和凸侧椎弓根轴心线与棘突轴心线所夹角度有显著差异，凹侧明显增大，凸侧明显减少；椎体旋转与棘突移位分级之间无相关性。     

Effects of scoliosis on respiratory muscle strength in patients with neuromuscular disorders

Background contextNeuromuscular disorders (NMD) are characterized by loss of lung volume and respiratory muscle weakness, but the effects of scoliosis on lung function are unclear.PurposeTo compare pulmonary function and respiratory muscle strength in patients with NMD with and without scoliosis as well as in healthy controls.Study design/settingProspective comparison of pulmonary function testing and respiratory muscle strength were made at the pediatric pulmonology and cardiopulmonary rehabilitation units of a university hospital.Patient sampleTwenty-two patients with NMD and scoliosis, 17 patients with NMD without scoliosis, and 24 age- and sex-matched healthy controls. Outcome measures were compared in patients with NMD with and without scoliosis and healthy subjects using Student t test, Mann-Whitney U test, chi-square test, one-way analysis of variance (ANOVA), Kruskal-Wallis one-way ANOVA, Pearson correlation coefficients, and Spearman rank correlation, as appropriate.Outcome measures1) Pulmonary function: forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), peak expiratory flow rate (PEF), forced expiratory flow between 25% and 75% of FVC (FEF_25–75%), and maximum expiratory flows at 75%, 50%, and 25% of FVC (MEF₇₅, MEF₅₀, and MEF₂₅, respectively); 2) oxygen saturation: pulse oxymeter reading; and 3) respiratory muscle strength: maximal inspiratory mouth pressure (MIP) and maximal expiratory mouth pressure (MEP).MethodsPulmonary function, oxygen saturation, MIP, and MEP were measured and compared in patients with NMD, patients with and without scoliosis, and in healthy subjects.ResultsThe patients with NMD, both with and without scoliosis, had significantly lower PEF, MIP, MEP, % predicted MIP (%MIP), and % predicted MEP (%MEP) than those of healthy subjects (p<.05). The patients with NMD and scoliosis had significantly lower values than those with NMD without scoliosis and controls (p<.05) for FVC, FEV₁, and FEF_25–75%.ConclusionBoth inspiratory and expiratory muscle strength were diminished in patients with NMD compared with healthy controls. Significant differences were also noted in pulmonary function in patients with NMD with or without scoliosis. This suggests that NMD may impact respiratory function independently of the effects of scoliosis. Clinicians treating patients with NMD should be aware of the possibility of compromised respiratory function in these patients to address possible complications.     

Effectiveness of cross-linking posterior segmental instrumentation in adolescent idiopathic scoliosis: a 2-year follow-up comparative study

Background contextSurgeons continue to debate the need for a cross-link (CL) in posterior spinal instrumentation constructs with segmental pedicle screws in adolescent idiopathic scoliosis (AIS). Advantage of CLs is increased stiffness of the construct, and disadvantages include added expense and risk of late operative-site pain and pseudarthrosis.PurposeTo compare the effectiveness of using CLs versus using no cross-links (NCLs) in posterior segmental instrumentation in AIS.Study designRetrospective comparative study, level of evidence 3.Patient sampleSeventy-five AIS patients less than 21 years of age, who underwent posterior spinal instrumentation with segmental pedicle screws (25 with CLs and 50 with NCLs) at a single institution with 2-year follow-up, are described.Outcome measuresPhysiologic measures include imaging: thoracic and lumbar Cobb angles, correction rate, apical vertebral translation (AVT), and apical vertebral rotation (AVR); self-report measures include Scoliosis Research Society (SRS) domain outcome scores.MethodsPreoperative (pre-op) and postoperative first erect, 1-year, and 2-year follow-up radiographs were measured. Instrumentation-related complications and normalized SRS scores were recorded. Independent sample t test, χ² test, and repeated-measures analysis of variance were used for analyses.ResultsThe average age at surgery was 14 years, the mean pre-op Cobb angle was 57°, and the mean number of levels fused was 10.9. The groups were similar preoperatively with respect to age, sex, Lenke curve, Cobb angle, AVT, and Risser grade and were similar intraoperatively for levels fused and anchor density. There was no difference in AVR, Cobb angle, correction rate, or AVT between the groups (p>.05). Complications included one wound infection in the CL group and one painful scar in the NCL group. There were no differences in SRS domain scores.ConclusionWe observed no differences in maintenance of correction, SRS scores, and complications with or without cross-linking posterior segmental instrumentation in AIS patients over 2-year follow-up. Further follow-up is necessary.     

Epidemiological aspects of scoliosis in a cohort of Japanese patients with Prader-Willi syndrome

Background contextThe prevalence of scoliosis in Prader-Willi syndrome (PWS) is high; however, the prevalence of PWS is rare, with one person in 10,000 to 20,000 affected. The etiology and characteristics of scoliosis associated with PWS remain unidentified. In addition, it is believed that the speedup of growth associated with growth hormone (GH) supplement treatment may influence the deterioration of scoliosis in PWS.PurposeTo investigate scoliosis in Japanese patients with PWS.Study designRetrospective observational study.Patient sampleWe investigated 101 patients (67 men, 34 women) who were followed up from November 2002 to January 2008. All patients were diagnosed using fluorescence in situ hybridization or the methylation test. Of the 101 patients, 80 had an inherited deletion of chromosome 15q11–13 (deletion) and 21 patients had no deletion, including those with uniparental disomy.Outcome measures1) Prevalence of scoliosis; 2) association of scoliosis with GH treatments; 3) association of scoliosis with genotype; 4) clarification of PWS scoliosis characteristics; and 5) analysis of severe PWS scoliosis patients (Cobb angle greater than 40°). Scoliosis for our study was defined as scoliosis with a Cobb angle greater than 10°.MethodsTo investigate PWS-associated scoliosis, we used spinal X-ray examinations. The pattern of scoliosis was classified into three types: primary single lumbar or thoracolumbar curve (Type 1), double curve (Type 2), and primary single thoracic curve (Type 3). For statistical analysis, chi-square tests for the distribution of patients were used (p<.05).Results1) Scoliosis was found in 38.6% (39/101) of patients with PWS. 2) There was no statistical difference in the prevalence of scoliosis between the GH treatment group (32.8%) and the GH nontreatment group (group with no GH treatments) (46.5%) (p=.16, chi-square test). 3) There was no statistical difference in the prevalence of scoliosis between the deletion group (38.8%) and the nondeletion group (38.1%) (p=.84, chi-square test). 4) Scoliosis was classified into three types, according to single or double curve scoliosis and position of scoliosis. The prevalence of these groups was 61.5% for Type 1 (primary single lumbar and thoracolumbar curve), 48.7% for lumbar curve convex on the left side, 28.2% for Type 2 (double curve), and 10.3% for Type 3 (primary single thoracic curve). 5) Severe scoliosis was found in nine patients (8.9%, 9/101). Type 2 was found in 66.7% (6/9) of patients with severe scoliosis. During the follow-up period, two patients changed from Type 1 to Type 2.ConclusionsScoliosis in PWS can be classified into three types. A lumbar curve convex on the left side was found in most patients. In addition, severe deterioration of scoliosis was found in Type 2 patients. Therefore we recommend careful, ongoing observations for patients showing double curve tendencies.     

Zonal differences in risk and pattern of pedicle screw perforations in adolescent idiopathic scoliosis (AIS): a computerized tomography (CT) review of 1986 screws

Purpose

To evaluate the zonal differences in risk and pattern of pedicle screw perforations in adolescent idiopathic scoliosis (AIS) patients.

Methods

The scoliosis curves were divided into eight zones. CT scans were used to assess perforations: Grade 0, Grade 1(< 2 mm), Grade 2(2–4 mm) and Grade 3(> 4 mm). Anterior perforations were classified into Grade 0, Grade 1(< 4 mm), Grade 2(4–6 mm) and Grade 3(> 6 mm). Grade 2 and 3 (except lateral grade 2 and 3 perforation over thoracic vertebrae) were considered as ‘critical perforations’.

Results

1986 screws in 137 patients were analyzed. The overall perforation rate was 8.4% after exclusion of the lateral perforation. The highest medial perforation rate was at the transitional proximal thoracic (PT)/main thoracic (MT) zone (6.9%), followed by concave lumbar (6.7%) and convex main thoracic (MT) zone (6.1%). The overall critical medial perforation rate was 0.9%. 33.3% occurred at convex MT and 22.2% occurred at transitional PT/MT zone. There were 39 anterior perforations (overall perforation rate of 2.0%). 43.6% occurred at transitional PT/MT zone, whereas 23.1% occurred at concave PT zone. The overall critical anterior perforation rate was 0.6%. 5/12 (41.7%) critical perforations occurred at concave PT zone, whereas four perforations occurred at the transitional PT/MT zone. There were only two symptomatic left medial grade 2 perforations (0.1%) resulting radiculopathy, occurring at the transitional main thoracic (MT)/Lumbar (L) zone.

Conclusion

Overall pedicle perforation rate was 8.4%. Highest rate of critical medial perforation was at the convex MT zone and the transitional PT/MT zone, whereas highest rate of critical anterior perforation was at the concave PT zone and the transitional PT/MT zone. The rate of symptomatic perforations was 0.1%.