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.

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Diffusion tensor tractography of the lumbar nerves before a direct lateral transpsoas approach to treat degenerative lumbar scoliosis

Journal of Neurosurgery Spine ◽

10.3171/2018.9.spine18834 ◽

2019 ◽

Vol 30 (4) ◽

pp. 461-469 ◽

Cited By ~ 1

Author(s):

Yawara Eguchi ◽

Masaki Norimoto ◽

Munetaka Suzuki ◽

Ryota Haga ◽

Hajime Yamanaka ◽

...

Keyword(s):

Diffusion Tensor ◽

Concave Side ◽

Control Group ◽

Degenerative Lumbar Scoliosis ◽

Convex Side ◽

Lumbar Scoliosis ◽

Transpsoas Approach ◽

Nerve Tracts ◽

Psoas Major ◽

The Relationship

OBJECTIVEThe purpose of this study was to determine the relationship between vertebral bodies, psoas major morphology, and the course of lumbar nerve tracts using diffusion tensor imaging (DTI) before lateral interbody fusion (LIF) to treat spinal deformities.METHODSDTI findings in a group of 12 patients (all women, mean age 74.3 years) with degenerative lumbar scoliosis (DLS) were compared with those obtained in a matched control group of 10 patients (all women, mean age 69.8 years) with low-back pain but without scoliosis. A T2-weighted sagittal view was fused to tractography from L3 to L5 and separated into 6 zones (zone A, zones 1–4, and zone P) comprising equal quarters of the anteroposterior diameters, and anterior and posterior to the vertebral body, to determine the distribution of nerves at various intervertebral levels (L3–4, L4–5, and L5–S1). To determine psoas morphology, the authors examined images for a rising psoas sign at the level of L4–5, and the ratio of the anteroposterior diameter (AP) to the lateral diameter (lat), or AP/lat ratio, was calculated. They assessed the relationship between apical vertebrae, psoas major morphology, and the course of nerve tracts.RESULTSAlthough only 30% of patients in the control group showed a rising psoas sign, it was present in 100% of those in the DLS group. The psoas major was significantly extended on the concave side (AP/lat ratio: 2.1 concave side, 1.2 convex side). In 75% of patients in the DLS group, the apex of the curve was at L2 or higher (upper apex) and the psoas major was extended on the concave side. In the remaining 25%, the apex was at L3 or lower (lower apex) and the psoas major was extended on the convex side. Significant anterior shifts of lumbar nerves compared with controls were noted at each intervertebral level in patients with DLS. Nerves on the extended side of the psoas major were significantly shifted anteriorly. Nerve pathways on the convex side of the scoliotic curve were shifted posteriorly.CONCLUSIONSA significant anterior shift of lumbar nerves was noted at all intervertebral levels in patients with DLS in comparison with findings in controls. On the convex side, the nerves showed a posterior shift. In LIF, a convex approach is relatively safer than an approach from the concave side. Lumbar nerve course tracking with DTI is useful for assessing patients with DLS before LIF.

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Impact of shift to the concave side of the C7-center sacral vertical line on de novo degenerative lumbar scoliosis progression in elderly volunteers

Journal of Orthopaedic Science ◽

10.1016/j.jos.2019.03.007 ◽

2020 ◽

Vol 25 (1) ◽

pp. 82-88

Author(s):

Hiroki Ushirozako ◽

Go Yoshida ◽

Tomohiko Hasegawa ◽

Yu Yamato ◽

Tatsuya Yasuda ◽

...

Keyword(s):

De Novo ◽

Concave Side ◽

Vertical Line ◽

Degenerative Lumbar Scoliosis ◽

Lumbar Scoliosis ◽

Scoliosis Progression

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Uniplanar cannulated pedicle screws in the correction of Lenke type 1 adolescent idiopathic scoliosis (AIS)

10.21203/rs.3.rs-34233/v1 ◽

2020 ◽

Author(s):

Yiwei Zhao ◽

Wubo Liu ◽

Suomao Yuan ◽

Yonghao Tian ◽

Xinyu Liu

Keyword(s):

Adolescent Idiopathic Scoliosis ◽

Idiopathic Scoliosis ◽

Pedicle Screws ◽

Vertebral Rotation ◽

Concave Side ◽

Convex Side ◽

X Rays ◽

Group A ◽

Group B

Abstract Background In the present study, we reported the clinical use of uniplanar cannulated pedicle screws for the correction of Lenke type 1 adolescent Idiopathic scoliosis (AIS), and its safety and clinical outcomes were also evaluated. Methods 68 patients with Lenke type 1 AIS were included, among which 38 patients were treated with uniplanar cannulated screws at the concave side of periapical levels and multiaxial screws at the other levels (group A). Moreover, the remaining 30 patients were treated with all multiaxial screws (group B). The preoperative and postoperative radiographic parameters of the Lenke type 1 AIS, axial vertebral rotation, and the safety of the pedicle screws were evaluated by X-rays and computed tomography (CT). Results Preoperative data was comparable between two groups. The postoperative proximal thoracic (PT) curve, main thoracic (MT) curve, thoracolumbar/lumbar (TL/L) curve, and apical vertebral rotation were significantly improved compared with the preoperative data. The coronal correction rates in group A and B were 83% and 81.9%, respectively (P > 0.05). The derotation rates in group A and B were 60.8% and 43.2%, respectively (P < 0.05). The rotation classification in the group A was also better compared with the group B. The misplacement rate in group A and B was 7.9% and 11.8%, respectively (P < 0.05), and the total misplacement rate on the concave side (11.4%) was higher than that of convex side (8.4%). The lateral perforation was found at the concave side, while the medial perforation was found at the convex side. On the concave side, the misplacement rate in group A and B was 9.7% and 12.3%, respectively (P < 0.05). The grades 2 and 3 perforations were three (3.5%) in the group A and eight (8.2%) in the group B (P < 0.05). On the convex side, the misplacement rate in group A and B was 5.9% and 11.1%, respectively (P < 0.05). The grades 2 and 3 perforations were one (0.9%) in the group A and four (4.4%) in the group B (P < 0.05). Conclusion Collectively, uniplanar cannulated pedicle screws could effectively increase the accuracy of pedicle screws and facilitate the derotation of the apical vertebra compared with the multiaxial pedicle screws. Trial registration retrospectively registered

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Comparison between oblique lumbar interbody fusion and posterior lumbar interbody fusion in the treatment of degenerative lumbar scoliosis: a retrospective clinical study

10.21203/rs.2.21443/v1 ◽

2020 ◽

Author(s):

chaojun Xu ◽

Yingjie HAO ◽

Lei YU ◽

Guangduo ZHU ◽

Zhinan REN ◽

...

Keyword(s):

Cobb Angle ◽

Interbody Fusion ◽

Posterior Lumbar Interbody Fusion ◽

Length Of Hospital Stay ◽

Vertical Axis ◽

Degenerative Lumbar Scoliosis ◽

Lumbar Interbody Fusion ◽

Lumbar Scoliosis ◽

Significant Difference ◽

Oblique Lumbar Interbody Fusion

Abstract Backgroud Few studies compared radiographic and clinical outcomes between oblique lumbar interbody fusion and posterior lumbar interbody fusion in degenerative lumbar scoliosis. Methods This study retrospectively analyzed the case data of 40 patients with degenerative lumbar scoliosis in our hospital from July 2016 to October 2018. Among which,19 cases underwent oblique lumbar Interbody fusion(OLIF group) and 21 cases underwent posterior lumbar interbody fusion(PLIF group). The duration of the operation, volume of intraoperative hemorrhage, incision length, bed rest time, length of hospital stay, and complications were recorded for all patients. The clinical effects of 40 patients were evaluated by VAS for back pain and Oswestry Disability Index (ODI) and The radiographic parameters were evaluated using the lumbar scoliosis Cobb angle, sagittal vertical axis(SVA), coronal vertical axis(CVA), lumbar lordosis(LL), pelvic tilt(PT), sacral slope(SS), and Disc height(DH). Results The duration of the operation, the volume of intraoperative hemorrhage, incision length, bed rest time, length of hospital stay of the OLIF group were shorter than the PLIF group( P ＜ 0.05 ). The VAS scores for back pain, the ODI of the two groups were significantly decreased, which compared with the preoperative( P ＜ 0.05 )，which in OLIF group was significantly more decreased than in PLIF( P ＜ 0.05 ) at 7 days and 3 months postoperatively, but at the last follow-up there were no significant difference between the two groups( P ＞ 0.05 ); The lumbar scoliosis Cobb angle, SVA, CVA, PT, LL, SS were significantly improved postoperatively( P ＜ 0.05 ). The OLIF group showed higher DH, smaller Cobb angle, and greater LL than the PLIF group at any time point( P ＜ 0.05 ). but there were no significant difference in SVA, CVA, PT and SS between the two groups at any follow-up points( P ＞ 0.05 ). The overall complication rate was slightly higher in the PLIF group（47.62%）than in the OLIF group（26.32%）without significant difference(x 2 =1.931, P =0.165). But the incidence of major complications in the PLIF group was significantly higher than that in the OLIF group (Fisher, P =0.026). Conclusion OLIF provides an alternative minimally invasive treatment for DLS, which compared with PLIF. It has the characteristics of a small incision, rapid recovery, fewer complications related to the surgical approach, and satisfactory orthopedics. Keywords : Minimally invasive, Oblique lumbar interbody fusion, Degenerative adult lumbar scoliosis , Posterior lumbar interbody fusion

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The surgical outcome of decompression alone versus decompression with limited fusion for degenerative lumbar scoliosis

Journal of Neurosurgery Spine ◽

10.3171/2018.1.spine17879 ◽

2018 ◽

Vol 29 (3) ◽

pp. 259-264 ◽

Cited By ~ 6

Author(s):

Kenji Masuda ◽

Takayuki Higashi ◽

Katsutaka Yamada ◽

Tatsuhiro Sekiya ◽

Tomoyuki Saito

Keyword(s):

Decision Making ◽

Cobb Angle ◽

Japanese Orthopaedic Association ◽

Spinal Instability ◽

Degenerative Lumbar Scoliosis ◽

Surgical Decision ◽

Lumbar Scoliosis ◽

Radiological Parameters ◽

Surgical Decision Making

OBJECTIVEThe aim of this study was to assess the usefulness of radiological parameters for surgical decision-making in patients with degenerative lumbar scoliosis (DLS) by comparing the clinical and radiological results after decompression or decompression and fusion surgery.METHODSThe authors prospectively planned surgical treatment for 298 patients with degenerative lumbar disease between September 2005 and March 2013. The surgical method used at their institution to address intervertebral instability is precisely defined based on radiological parameters. Among 64 patients with a Cobb angle ranging from 10° to 25°, 57 patients who underwent follow-up for more than 2 years postoperatively were evaluated. These patients were divided into 2 groups: those in the decompression group underwent decompression alone (n = 25), and those in the fusion group underwent decompression and short segmental fusion (n = 32). Surgical outcomes were reviewed, including preoperative and postoperative Cobb angles, lumbar lordosis based on radiological parameters, and Japanese Orthopaedic Association (JOA) scores.RESULTSThe JOA scores of the decompression group and fusion group improved from 5.9 ± 1.6 to 10.0 ± 2.8 and from 7.2 ± 2.0 to 11.3 ± 2.8, respectively, which was not significantly different between the groups. At the final follow-up, the postoperative Cobb angle in the decompression group changed from 14° ± 2.9° to 14.3° ± 6.4° and remained stable, while the Cobb angle in the fusion group decreased from 14.8° ± 4.0° to 10.0° ± 8.5° after surgery.CONCLUSIONSThe patients in both groups demonstrated improved JOA scores and preserved Cobb angles after surgery. The improvement in JOA scores and preservation of Cobb angles in both groups show that the evaluation of spinal instability using radiological parameters is appropriate for surgical decision-making.

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Methylation of estrogen receptor 2 (ESR2) in deep paravertebral muscles and its association with idiopathic scoliosis

Scientific Reports ◽

10.1038/s41598-020-78454-4 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Małgorzata Chmielewska ◽

Piotr Janusz ◽

Mirosław Andrusiewicz ◽

Tomasz Kotwicki ◽

Małgorzata Kotwicka

Keyword(s):

Dna Methylation ◽

Estrogen Receptor ◽

Idiopathic Scoliosis ◽

Cobb Angle ◽

Methylation Level ◽

Gene Promoter ◽

Concave Side ◽

Convex Side ◽

Paravertebral Muscles ◽

Moderate Negative Correlation

AbstractIdiopathic scoliosis (IS) is one of the most common spinal disorders in adolescents. Despite many studies, the etiopathogenesis of IS is still poorly understood. In recent years, the role of epigenetic factors in the etiopathogenesis of IS has been increasingly investigated. It has also been postulated that the development and progression of the disease is related to gender and puberty, and could be associated with estrogen action. Estrogen hormones act via estrogen receptor 1 (ESR1) and estrogen receptor 2 (ESR2). It has been suggested that ESR2 expression is dependent on methylation within its gene promoter. So far, no studies have evaluated local, tissue-specific DNA methylation in patients with IS. Thus, our study aimed to analyze the methylation and expression level of ESR2 in the paraspinal muscles of the convex and concave side of the IS curvature. The methylation level within ESR2 promoter 0N, but not exon 0N, was significantly higher on the concave side of the curvature compared to the convex side. There was no significant correlation between ESR2 expression and methylation level in the promoter 0N on the convexity of thoracic scoliosis, whereas, on the concave side of the curvature, we observed a moderate negative correlation. There was no difference in the methylation levels of the ESR2 promoter and exon 0N between groups of patients with Cobb angle ≤ 70° and > 70° on the concave and convex side of the curvature. We also found no statistically significant correlation between the Cobb angle value and the mean methylation level in either the ESR2 promoter or exon 0N on the convex or concave side of the curvature. Our findings demonstrate that DNA methylation at the ESR2 promoter in deep paravertebral muscle tissue is associated with the occurrence but not with the severity of idiopathic scoliosis.

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Comparison of percutaneous transforaminal endoscopic decompression and short-segment fusion in the treatment of elderly degenerative lumbar scoliosis with spinal stenosis

BMC Musculoskeletal Disorders ◽

10.1186/s12891-021-04804-6 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Pengfei Li ◽

Yuexin Tong ◽

Ying Chen ◽

Zhezhe Zhang ◽

Youxin Song

Keyword(s):

Cobb Angle ◽

Clinical Outcomes ◽

Spinal Stenosis ◽

Disc Height ◽

Degenerative Lumbar Scoliosis ◽

Short Segment ◽

Lumbar Scoliosis ◽

Endoscopic Decompression ◽

Significant Difference ◽

Segmental Lordosis

Abstract Background Degenerative lumbar scoliosis (DLS) combined with spinal stenosis is increasingly being diagnosed in the elderly. However, the appropriate surgical approach remains somewhat controversial. The aim of this study was to compare the results of percutaneous transforaminal endoscopic decompression (PTED) and short-segment fusion for the treatment of mild degenerative lumbar scoliosis combined with spinal stenosis in older adults over 60 years of age. Methods Of the 54 consecutive patients included, 30 were treated with PTED and 24 were treated with short-segment open fusion. All patients were followed up for at least 12 months (12–24 months). Patient demographics, and perioperative and clinical outcomes were recorded. Visual analog scale (VAS) scores, Oswestry disability index (ODI) scores, and modified Macnab criteria were used to assess clinical outcomes. At the same time, changes in disc height, segmental lordosis, coronal Cobb angle, and lumbar lordosis were compared. Results The mean age was 68.7 ± 6.5 years in the PTED group and 66.6 ± 5.1 years in the short-segment fusion group. At 1 year postoperatively, both groups showed significant improvement in VAS and ODI scores compared with preoperative scores (p < 0.05), with no statistically significant difference between groups. However, VAS-Back and ODI were lower in the PTED group at 1 week postoperatively (p < 0.05). According to the modified Macnab criteria, the excellent rates were 90.0 and 91.6% in the PTED and short-segment fusion groups, respectively. However, the PTED group had a significantly shorter operative time, blood loss, postoperative hospital stay, postoperative bed rest, and complication rate. There was no significant difference in radiological parameters between the two groups preoperatively. At the last follow-up, there were significant differences in disc height, segmental lordosis at the L4–5 and L5–S1 levels, and Cobb angle between the two groups. Conclusion Both PTED and short-segment fusion for mild degenerative lumbar scoliosis combined with spinal stenosis have shown good clinical results. PTED under local anesthesia may be an effective supplement to conventional fusion surgery in elderly patients with DLS combined with spinal stenosis.

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Adult's Degenerative Scoliosis: Midterm Results of Dynamic Stabilization without Fusion in Elderly Patients—Is It Effective?

Advances in Orthopedics ◽

10.1155/2013/365059 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 6

Author(s):

Mario Di Silvestre ◽

Francesco Lolli ◽

Tiziana Greggi ◽

Francesco Vommaro ◽

Andrea Baioni

Keyword(s):

Elderly Patients ◽

Cobb Angle ◽

Pedicle Screw ◽

Statistical Significance ◽

Degenerative Spondylolisthesis ◽

Clinical Results ◽

Dynamic Stabilization ◽

Sagittal Imbalance ◽

Degenerative Lumbar Scoliosis ◽

Lumbar Scoliosis

Study Design. A retrospective study.Purpose. Posterolateral fusion with pedicle screw instrumentation used for degenerative lumbar scoliosis can lead to several complications. In elderly patients without sagittal imbalance, dynamic stabilization could represent an option to avoid these adverse events.Methods. 57 patients treated by dynamic stabilization without fusion were included. All patients had degenerative lumbarde novoscoliosis (average Cobb angle 17.2°), without sagittal imbalance, associated in 52 cases (91%) with vertebral canal stenosis and in 24 (42%) with degenerative spondylolisthesis. Nineteen patients (33%) had previously undergone lumbar spinal surgery.Results. At an average followup of 77 months, clinical results improved with statistical significance. Scoliosis Cobb angle was 17.2° (range, 12° to 38°) before surgery and 11.3° (range, 4° to 26°) at last follow-up. In the patients with associated spondylolisthesis, anterior vertebral translation was 19.5% (range, 12% to 27%) before surgery, 16.7% (range, 0% to 25%) after surgery, and 17.5% (range, 0% to 27%) at followup. Complications incidence was low (14%), and few patients required revision surgery (4%).Conclusions. In elderly patients with mild degenerative lumbar scoliosis without sagittal imbalance, pedicle screw-based dynamic stabilization is an effective option, with low complications incidence, granting curve stabilization during time and satisfying clinical results.

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Radiologic prognostic factors of curve progression in early degenerative lumbar scoliosis

Journal of Neurosurgery Spine ◽

10.3171/2020.7.spine20266 ◽

2021 ◽

pp. 1-7

Author(s):

Jin-Sung Park ◽

Se-Jun Park ◽

Chong-Suh Lee ◽

Tae-hoon Yum ◽

Bo-Taek Kim

Keyword(s):

Cobb Angle ◽

Curve Progression ◽

Degenerative Lumbar Scoliosis ◽

Disc Space ◽

Lumbar Scoliosis ◽

Radiological Parameters ◽

Lateral Subluxation ◽

Lower Disc ◽

The Mean

OBJECTIVESeveral radiological parameters related to the aging spine have been reported as progression factors of early degenerative lumbar scoliosis (DLS). However, it has not been determined which factors are the most important. In this study the authors aimed to determine the risk factors associated with curve progression in early DLS.METHODSFifty-one patients with early DLS and Cobb angles of 5°–15° were investigated. In total, 7 men and 44 women (mean age 61.6 years) were observed for a mean period of 13.7 years. The subjects were divided into two groups according to Cobb angle progression (≥ 15° or < 15°) at the final follow-up, and radiological parameters were compared. The direction of scoliosis, apical vertebral level and rotational grade, lateral subluxation, disc space difference, osteophyte difference, upper and lower disc wedging angles, and relationship between the intercrest line and L5 vertebra were evaluated.RESULTSDuring the follow-up period, the mean curve progression increased from 8.8° ± 3.2° to 19.4° ± 8.9°. The Cobb angle had progressed by ≥ 15° in 17 patients (33.3%) at the final follow-up. In these patients the mean Cobb angle increased from 9.4° ± 3.4° to 28.8° ± 7.5°, and in the 34 remaining patients it increased from 8.5° ± 3.1° to 14.7° ± 4.8°. The baseline lateral subluxation, disc space difference, and upper and lower disc wedging angles significantly differed between the groups. In multivariate logistic regression analysis, only the upper and lower disc wedging angles were significantly correlated with curve progression (OR 1.55, p = 0.035, and OR 1.89, p = 0.004, respectively).CONCLUSIONSAsymmetrical degenerative change in the lower apical vertebral disc, which leads to upper and lower disc wedging angles, is the most substantial factor in predicting early DLS progression.

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The biomechanical effect of single-level laminectomy and posterior instrumentation on spinal stability in degenerative lumbar scoliosis: a human cadaveric study

Neurosurgical FOCUS ◽

10.3171/2019.2.focus1911 ◽

2019 ◽

Vol 46 (5) ◽

pp. E15 ◽

Cited By ~ 5

Author(s):

Christine M. E. Rustenburg ◽

Sayf S. A. Faraj ◽

Roderick M. Holewijn ◽

Idsart Kingma ◽

Barend J. van Royen ◽

...

Keyword(s):

Disc Degeneration ◽

Posterior Instrumentation ◽

Pedicle Screws ◽

Spinal Instability ◽

Degenerative Lumbar Scoliosis ◽

Spinal Stability ◽

Degenerative Scoliosis ◽

Single Level ◽

Lumbar Scoliosis ◽

Flexion Extension

OBJECTIVEDegenerative lumbar scoliosis, or de novo degenerative lumbar scoliosis, can result in spinal canal stenosis, which is often accompanied by disabling symptoms. When surgically treated, a single-level laminectomy is performed and short-segment posterior instrumentation is placed to restore stability. However, the effects of laminectomy on spinal stability and the necessity of placing posterior instrumentation are unknown. Therefore, the aim of this study was to assess the stability of lumbar spines with degenerative scoliosis, characterized by the range of motion (ROM) and neutral zone (NZ) stiffness, after laminectomy and placement of posterior instrumentation.METHODSTen lumbar cadaveric spines (T12–L5) with a Cobb angle ≥ 10° and an apex on L3 were included. Three loading cycles were applied per direction, from −4 Nm to 4 Nm in flexion/extension (FE), lateral bending (LB), and axial rotation (AR). Biomechanical evaluation was performed on the native spines and after subsequent L3 laminectomy and the placement of posterior L2–4 titanium rods and pedicle screws. Nonparametric and parametric tests were used to analyze the effects of laminectomy and posterior instrumentation on NZ stiffness and ROM, respectively, both on an individual segment’s motion and on the entire spine section. Spearman’s rank correlation coefficient was used to study the correlation between disc degeneration and spinal stability.RESULTSThe laminectomy increased ROM by 9.5% in FE (p = 0.04) and 4.6% in LB (p = 0.01). For NZ stiffness, the laminectomy produced no significant effects. Posterior instrumentation resulted in a decrease in ROM in all loading directions (−22.2%, −24.4%, and −17.6% for FE, LB, and AR, respectively; all p < 0.05) and an increase in NZ stiffness (+44.7%, +51.7%, and +35.2% for FE, LB, and AR, respectively; all p < 0.05). The same changes were seen in the individual segments around the apex, while the adjacent, untreated segments were mostly unaffected. Intervertebral disc degeneration was found to be positively correlated to decreased ROM and increased NZ stiffness.CONCLUSIONSLaminectomy in lumbar spines with degenerative scoliosis did not result in severe spinal instability, whereas posterior instrumentation resulted in a rigid construct. Also, prior to surgery, the spines already had lower ROM and higher NZ stiffness in comparison to values shown in earlier studies on nonscoliotic spines of the same age. Hence, the authors question the clinical need for posterior instrumentation to avoid instability.

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