Lowest Instrumented Vertebra Research Articles

Is It Enough to Stop Distal Fusion at L3 in Mild to Moderate Lenke 5C Adolescent Idiopathic Scoliosis Patients?

There has been no definitive conclusion on the selection of the lowest instrumented vertebra (LIV) in Lenke 5C adolescent idiopathic scoliosis (AIS) patients. The purpose of this study was to evaluate whether it is enough to stop distal fusion at L3 in mild to moderate Lenke 5C AIS patients with posterior selective lumbar fusion, Ponte osteotomies and segmental direct vertebra rotation and to analyze the risk factors for postoperative complications in patients selecting L3 as the LIV. A retrospective review was conducted on 106 Lenke 5C AIS patients who underwent corrective surgery in our institution from 2010 to 2021, with a minimum 2-year follow-up. The LIV was L3 or L4. According to the LIV, patients were initially divided into Group I (the LIV was L3) and Group II (the LIV was L4). Then, Group I was further divided into a complication group and a non-complication group. Demographics, radiological parameters, postoperative complications, and clinical outcomes were recorded. Univariate analysis and multivariate logistic analysis were used to identify the risk factors for postoperative complications in patients with L3 as the LIV. There were no significant differences in the demographics, radiological parameters, postoperative complications, or clinical outcomes between Group I and Group II (p > 0.05), and the outcomes were satisfactory in both groups. The main postoperative complications were distal adding-on (11 cases), coronal imbalance (16 cases), proximal junctional kyphosis (2 cases), and internal fixation failure (4 cases). Logistic regression analysis revealed that age and postoperative C7-CSVL were independent predictors of postoperative complications when selecting L3 as the LIV. Terminating the distal fusion level at L3 was practical for mild to moderate Lenke 5C AIS patients. For patients selecting L3 as the LIV, younger patients should be cautious, and maintaining postoperative coronal balance is necessary for avoiding postoperative complications.

Does Restoration of Lumbar and Segmental Cobb Angle Affect Fusion Outcome in Short-Segment Posterior Lumbar Fusion?

To study the effect of lumbar lordosis change and pelvic parameters on surgical outcomes such as fusion vs. non-fusion (pseudarthrosis), Adjacent Segment Pathology (ASP), and re-operation in patients undergoing 1-, 2- and 3-level PLF. Adult patients with degenerative spine pathologies who had undergone PLF between L2 and L5 levels at an academic center between 2010 and 2020 were included. Pre-operative and early post-operative lateral standing X-Rays of the lumbar spine were used to measure pre-operative lumbar Cobb angle, Postoperative lumbar Cobb angle, pre-operative segmental Cobb angle (measured from the superior endplate of the upper instrumented vertebra to the inferior endplate of the lower instrumented vertebra), postoperative segmental Cobb angle, preoperative pelvic incidence (PI) and pelvic tilt (PT). Change in lumbar and segmental Cobb was calculated as postoperative Cobb angle (lumbar and segmental) minus preoperative Cobb angle. A total of 243 patients met our inclusion and exclusion criterion. Patients who had pseudarthrosis had a significantly less restoration of lumbar lordosis compared to those who did not, both for lumbar cobb angle change (-5.2±8.2 vs. -0.2±8.2; p=0.01) and segmental cobb angle change (-5.4±6.6 vs. -1.5±6.0; p=0.01). Moreover, PI was lower in patients who developed ASP vs. those who didn't. There was no significant difference in these measures (lumbar cobb angle changes and segmental cobb angle change) in patients who experienced ASP and those who did not. Better restoration of lumbar lordosis reduces rates of pseudarthrosis after short-segment PLF but has no association with rates of ASP.

Excessive posterior placement of upper instrumented vertebra relative to lower instrumented vertebra as a predictor of proximal junction kyphosis after selective spinal fusion for adolescent idiopathic scoliosis Lenke type 5C curves.

We defined sagittal S-line tilt (SSLT) as the tilt of the line connecting the upper instrumented vertebra and the lower instrumented vertebra. This study aimed to: (1) examine the correlation between SSLT and proximal junctional angle (PJA) change values, and (2) determine the cut-off value of SSLT with respect to proximal junctional kyphosis (PJK) occurrence. Eighty-six consecutive patients (81 female and 5 male; mean age: 15.8years) with Lenke 5C AIS who underwent posterior selective spinal fusion. Pearson's correlation coefficients were used to examine the relationship between preoperative SSLT and changes in PJA from preoperative to 2years postoperative. The impact of SSLT on PJK at 2years after surgery was assessed using a receiver operating characteristic (ROC) curve. We observed a moderate positive correlation between preoperative SSLT and change in PJA (R = 0.541, P < 0.001). We identified 18 patients (21%) with PJK at 2years postoperative. Mean preoperative SSLT in the PJK group and the non-PJK group differed significantly at 23.3 ± 4.1° and 16.1 ± 5.0°, respectively (P < 0.001). The cut-off value of preoperative SSLT for PJK at 2years postoperative was 18° in ROC curve analysis, with a sensitivity of 94%, specificity of 68%, and area under the ROC curve of 0.868. In selective lumbar fusion for AIS Lenke type 5C curves, preoperative SSLT was significantly correlated with PJA change from preoperative to 2years postoperative. SSLT was a predictor of PJK occurrence, with a cut-off value of 18°.

The Impact of the Lowest Instrumented Vertebra on the Correction of the Minor Curve During Selective Fusion in Patients With Adolescent Idiopathic Scoliosis.

Retrospective single-center data analysis. The aim of this investigation was to give advises for choosing the LIV in selective fusion to reach the best correction of the minor curve and sagittal profile. Scoliotic curves can be classified as structural or nonstructural. If selective fusion is performed, the nonstructural curves are not instrumented. The choice of the lowest instrumented vertebra (LIV) and the impact of different levels of the LIV on the correction of the minor curve in the frontal profile and on the sagittal balance is under debate. Forty-seven consecutive patients treated by posterior instrumented fusion were included in this retrospective investigation. Impact of the level of the LIV with regard to distance to end vertebra (EV), to the stable vertebra (StV), to the sagittal infliction point (IP), and to the apex of the lumbar lordosis on the correction of the minor curve was analyzed. Distance of LIV to EV was significant with regard to correction of the minor curve if it was more than 5 levels (P<0.001). Distance of LIV to StV was significant with regard to correction of the minor curve if it was more than 4 levels (P<0.01). Distance of LIV to IP was significant with regard to correction of the minor curve if it was more than 2 levels (P<0.01). Choosing a LIV that was more than 2 levels higher or lower than the sagittal infliction point showed a significantly higher correction of the minor curve. We therefore recommend to keep that distance when LIV is chosen.

Distal Junctional Failure: A Feared Complication of Multilevel Posterior Spinal Fusions.

Objectives: Distal junctional failure (DJF) is less commonly described than proximal junctional failure following posterior spinal fusion, and particularly adult spinal deformity (ASD) surgery. We describe a case series of patients with DJF, taking into account sagittal spinopelvic alignment, and suggest potential risk factors in light of the current literature. Methods: We performed a single-center, retrospective review of posterior spinal fusion patients with DJF who underwent subsequent revision surgery between June 2009 and January 2019. Demographics and surgical details were collected. Radiographical measurements included the following: preoperative and postoperative sagittal and coronal alignment for each index or revision surgery. The upper-instrumented vertebra (UIV), lower instrumented vertebra (LIV), and fusion length were recorded. Results: Nineteen cases (64.7 ± 13.5 years, 12 women, seven men) were included. The mean follow-up was 4.7 ± 2.4 years. The number of instrumented levels was 6.79 ± 2.97. Among the patients, 84.2% (n = 16) presented at least one known DJF risk factor. LIV was frequently L5 (n = 10) or S1 (n = 2). Six patients had an initial circumferential fusion at the distal end. Initial DJFs were vertebral fracture distal to the fusion (n = 5), screw pull-out (n = 9), spinal stenosis (n = 4), instability (n = 4), and one early DJK. The distal mechanical complications after a first revision included screw pull-out (n = 4), screw fracture (n = 3), non-union (n = 2), and an iatrogenic spondylolisthesis. Conclusions: In this case series, insufficient sagittal balance restoration, female gender, osteoporosis, L5 or S1 LIV in long constructs were associated with DJF. Restoring spinal balance and circumferentially fusing the base of constructs represent key steps to maintain correction and prevent revisions.

Axial rod slip at the end-of-construct screw in scoliosis surgery: relevance, occurrence and prevention

PurposeDespite standardized biomechanical tests for spinal implants, we recently recognized pedicle screw failure to maintain the rod fixated as a clinical concern in scoliosis surgery. This occurrence study investigates the risk and magnitude of axial rod slip (ARS), its relation with technique and preventive measures.MethodsRetrospective multicenter review of all primary scoliosis cases (2018–2020) with > 1 year FU from three centers, instrumented with uniplanar screws and 5.5 mm CoCr rods (Mesa 2, Stryker Corporation, Kalamazoo, MI, USA). ARS was defined as > 1 mm change in residual distal rod length from the screw in the lowest instrumented vertebra (LIV) and assessed by two independent observers. Slip distance, direction, relation to distal screw density and time of observation were recorded, as well as the effect of ARS on caudal curve increase. To prevent slip, more recent patients were instrumented with a different end-of-construct screw (Reline, NuVasive Inc. San Diego, CA, USA) and analyzed for comparison.ResultsARS risk was 27% (56/205) with a distance of 3.6 ± 2.2 mm, predominantly convex. 42% occurred before 4 months, the rest before 1 year. The caudal curve substantially increased three times more often in patients with ARS. Interobserver reliability was high and slip was in the expected direction. ARS was unrelated to distal screw density. Remarkable variation in ARS rates (53%, 31%, 13%) existed between the centers, while there was no difference in mean screw density (≈1.3 screws/level) or curve correction (≈60%). Revision surgery for ARS was required in 2.9% (6/207). Using the different end-of-construct screw, ARS risk was only 2% (1/56) and no revisions were required.ConclusionThis study demonstrates the prevalence of axial rod slip at the end of construct in scoliosis surgery and its clinical relevance. While minimal ARS can be subclinical, ARS should not be mistaken for adding on. The most severe ARS predominantly occurred convex at the high-loaded distal screw when L3 was the LIV. Longer constructs (LIV L3 or L4) have a higher risk of ARS. The minimal risk of ARS with another end-of-construct screw underscores the influence of screw type on ARS occurrence in our series. Further research is essential to refine techniques and enhance patient outcomes.

Comparison between the lowest instrumented vertebrae L3 with the use of direct vertebrae rotation (DVR) and the lowest instrumented vertebrae L4 for non-DVR in adolescents with idiopathic scoliosis Lenke 5C/6C: when LEV is L4

ObjectiveAs there are no substantial selection criteria for determining the lowest instrumented vertebra (LIV) in adolescent idiopathic scoliosis (AIS) Lenke 5C/6C, thus, many surgeons base their selection on experience. The study aims to compare the selection of the lowest instrumented vertebrae (LIV) lumbar vertebra three (L3) with the use of direct vertebrae rotation (DVR) to the lowest instrumented vertebrae (LIV) lumbar vertebra four (L4) with the use of non-DVR for the correction of adolescent idiopathic scoliosis (AIS) Lenke 5C/6C when the lower end vertebrae (LEV) is at lumbar vertebrae four (L4).MethodsThis prospective study involved 101 patients who were divided into two groups based on different techniques. The patients were prospectively followed up for at least four years. All patients included in the study had a lower end vertebra (LEV) at L4, while patients older than 18 years and patients with prior surgical procedures were excluded. The DVR group consisted of 49 patients, and the non-DVR group included 51 patients.ResultsThe preoperative mean LIV disc angle was 3.1 ± 3 and 3.1 ± 1, P = 0.097, which corrected to 1.2 ± 0 and 1.1 ± 0 in both groups at 4-year follow-up without statistical significance. The LIVDA and LIVT were statistically insignificant at the preoperative, and there were no significant differences at the follow-up visitation. The DVR group achieved a satisfactory coronal and Cobb’s angle correction compared to the NDVR group; however, there were no statistical differences at the follow-up visitations. Both groups achieve a satisfactory correction rate without substantial significance in clinical and radiological outcomes. Furthermore, no post-surgical complications were recorded in either group.ConclusionsDVR is suitable for selecting L3 as the LIV in AIS Lenke 5C/6C compared to L4 in non-DVR. DVR preserved more segments without substantial complications during the follow-up visitations. Nevertheless, both groups will continue to be followed up to prevent adding-on post-surgical complications.

P173. The role of the stable sagittal vertebra on lower instrumented vertebra selection in adult idiopathic scoliosis

P173. The role of the stable sagittal vertebra on lower instrumented vertebra selection in adult idiopathic scoliosis

P150. Optimizing lower instrumented vertebra selection in adult idiopathic scoliosis using preoperative upright and supine last touched vertebra

P150. Optimizing lower instrumented vertebra selection in adult idiopathic scoliosis using preoperative upright and supine last touched vertebra

Screw Motion Used in Semiconstrained Rotational Plate Systems for Anterior Cervical Discectomy and Fusion.

Retrospective observational study. To scrutinize screw motion used in semiconstrained rotational plate systems for anterior cervical discectomy and fusion (ACDF). Semiconstrained rotational plate systems are supposed to control graft subsidence and facilitate lordosis acquisition and maintenance by toggling the instrumented vertebrae via variable-angle screws. However, their benefits may be unrealized if the screws move within the vertebrae. We reviewed medical records of 119 patients who underwent 1-level, 2-level, 3-level, or 4-level ACDF, divided them into the short-segment (n=62, 1-level or 2-level ACDF) and long-segment (n=59, 3- level or 4-level ACDF) groups, and investigated their immediate and 1-year postoperative lateral radiographs. We measured the fused segmental angle, screw angles at the upper-instrumented vertebra (UIV) and lower-instrumented vertebra (LIV), distance from the screw base to the endplate of UIV/LIV (SBE), and distance from the screw tip to the endplate of UIV/LIV (STE) to analyze the screw motion used in these plate systems. The differences between the immediate and 1-year postoperative values were statistically analyzed. The nonunion level was also investigated. Screw angle and SBE at the LIV significantly decreased in the long-segment group (-14.5±9.8 degrees and -2.8±1.8mm, respectively) compared with those in the short-segment group (-4.6±6.0 degrees and -1.0±1.5mm, respectively). Thus, the long-segment group could not maintain the immediate-postoperative segmental angle. Overall, 27 patients developed nonunion, with 19 (70.4%) in the long-segment group and 21 (77.8%) at the lowest fused level. Semiconstrained rotational plate systems provide only vertical forces to the fused segment rather than toggling the instrumented vertebrae. Postoperatively in multilevel ACDF, LIV screws migrate caudally, suggesting that these plate systems are not always effective in maintaining lordosis. Moreover, LIV screws and the anterior wall of the LIV are subject to overloading, resulting in a high rate of nonunion at the lowest fused level. Level III.

Bipolar hybrid posterior instrumentation tecnique for the correction of Scheuermann's kyphosis.

Scheuermann´s kyphosis (SK) is the most common cause of painful and progressive structural hyperkyphosis in adolescents. Surgical treatment should be considered in cases of refractory pain or progressive deformities. We present the clinical and radiological results obtained using a bipolar, hybrid posterior instrumentation tecnique. We analysed 12 males and 6 females, with mean age of 15.8years. Minimum follow-up was 2years. We used transverse process hooks at the cranial level and polyaxial screws for the remaining levels. We did not instrument the periapical segment. We used the sagittal stable vertebra (SSV) as the lower instrumented vertebra (LIV) in most cases, the "barely touched SSV" if the above disc space is lordotic. The mean preoperative kyphosis was 73.6º, mean postoperative kyphosis 44.7º, and mean correction of 28.9º (p = 0.0002). The mean reduction in lumbar lordosis (LL) was 8.9º (p = 0.0018). There were no significant differences in the spinopelvic parameters or sagittal balance. The mean number of instrumented levels was 8.9. Type II osteotomies were necessary in only three patients. Three patients had a cranial sagittal angle greater than 10°, all of them asymptomatic. Postoperatively, all patients had VAS scores less than 2 and SRS-22 scores greater than 4. Hybrid bipolar posterior instrumentation offers adequate curve correction, less operative time, implant density, bleeding, material protrusion and risk of spinal cord injury, leaving a large periapical bed for graft supply. We propose to measure the flexibility of the curve in MRI. In flexible curves (those that correct at least 20% in the supine decubitus position), wide facetectomies offer adequate correction of the deformity.

The Optimal Lowest Instrumented Vertebra to Prevent the Distal Adding-On Phenomenon in Patients Undergoing Selective Thoracic Fusion for Adolescent Idiopathic Scoliosis with Lenke Type 1A and 1B Curves: Comparison of Nine Selection Criteria.

Background/Objectives: There is no solid consensus regarding which lowest instrumented vertebra (LIV) selection criterion is best to prevent distal adding-on (DA) after adolescent idiopathic scoliosis (AIS) surgery. This study aims to search out the LIV selection criteria in the literature and to compare the ability of each LIV selection criterion to prevent DA in patients with AIS. Methods: Patients who underwent thoracic fusion for AIS of Lenke type 1A or 1B were included in this study. Nine criteria for LIV selection were found in a literature review. For each patient, whether the postoperative actual location of LIV was met with the suggested locations of the LIV was assessed. The preventive ability of nine criteria against DA was evaluated using logistic regression analysis. The patients who met the LIV selection criteria but developed DA were investigated. Results: The study cohort consisted of 145 consecutive patients with a mean age of 14.8 years. The criteria of Suk (OR = 0.267), Parisini (OR = 0.230), Wang (OR = 0.289), and Qin (OR = 0.210) showed a significantly decreased risk of DA if the LIV selection criterion was chosen at each suggested landmark. As the additional levels were fused, there was no statistically significant benefit in further reducing the risk of DA. Among the patients who met each criterion, the incidence of DA was lower in criteria by Takahashi (5.9%), Qin (7.1%), and King (7.4%) than the others. Conclusions: Qin's criterion, using the substantially touching vertebra concept, has the highest preventive ability against DA development. Extending the instrumentation further distal to this suggested LIV criterion did not add further benefit.

Prediction of Screw Loosening After Dynamic Pedicle Screw Fixation With Lumbar Polyetheretherketone Rods Using Magnetic Resonance Imaging-Based Vertebral Bone Quality Score

Objective: To investigate the correlation between magnetic resonance imaging-based vertebral bone quality (VBQ) score and screw loosening after dynamic pedicle screw fixation with polyetheretherketone (PEEK) rods, and evaluate its predictive value.Methods: A retrospective analysis was conducted on the patients who underwent dynamic pedicle screw fixation with PEEK rods from March 2017 to June 2022. Data on age, sex, body mass index, hypertension, diabetes, hyperlipidemia history, long-term smoking, alcohol consumption, VBQ score, L1–4 average Hounsfield unit (HU) value, surgical fixation length, and the lowest instrumented vertebra were collected. Logistic regression analysis was employed to assess the relationship between VBQ score and pedicle screw loosening (PSL).Results: A total of 24 patients experienced PSL after surgery (20.5%). PSL group and non-PSL group showed statistical differences in age, number of fixed segments, fixation to the sacrum, L1–4 average HU value, and VBQ score (p &lt; 0.05). The VBQ score in the PSL group was higher than that in the non-PSL group (3.56 ± 0.45 vs. 2.77 ± 0.31, p &lt; 0.001). In logistic regression analysis, VBQ score (odds ratio, 3.425; 95% confidence interval, 1.552–8.279) were identified as independent risk factors for screw loosening. The area under the receiver operating characteristic curve for VBQ score predicting PSL was 0.819 (p &lt; 0.05), with the optimal threshold of 3.15 (sensitivity, 83.1%; specificity, 80.5%).Conclusion: The VBQ score can independently predict postoperative screw loosening in patients undergoing lumbar dynamic pedicle screw fixation with PEEK rods, and its predictive value is comparable to HU value.

Prediction Model for Lumbar Curve Correction After Selective Thoracic Fusion in Lenke 1 and 2 Adolescent Idiopathic Scoliosis.

A retrospective study. To identify independent risk factors and construct a prediction model for lumbar curve correction (LCC) after selective thoracic fusion (STF) in patients with Lenke 1 and 2 adolescent idiopathic scoliosis (AIS). STF has been widely applied to Lenke 1 and 2 AIS patients. However, LCC after STF is still controversial. One hundred twenty-eight patients undergoing STF with at least 2 years of follow-up were included. Cases were divided into a high-LCC group and a low-LCC group according to a rounded-up median of 65%. Forty-nine variables were taken into account. Logistic regression was applied to identify independent predictive factors. A prediction model was established by backward stepwise regression, and its evaluation was implemented on R. Five parameters showed independent predictive value for low LCC: right shoulder higher before surgery (right shoulder higher versus balanced: odds ratio [OR]=0.244, P =0.014), postoperative Cobb angle of lumbar curve (LC) (OR=1.415, P =0.001, cutoff value=11°), lowest instrumented vertebra (LIV) distal to end vertebra (no vs. yes: OR=4.587, P =0.013), postoperative LIV tilt (OR=0.686, P =0.010, cutoff value=6.85°) and postoperative LIV+1 tilt (OR=1.522, P =0.005, cutoff value=6.25°). The prediction model included 6 variables: lumbar modifier, preoperative shoulder balance, postoperative Cobb angle of LC, LIV position, postoperative LIV tilt, and postoperative LIV+1 tilt. The model evaluation demonstrated satisfactory capability and stability (area under curve=0.890, 10-fold cross-validation accuracy=0.782). Preoperative shoulder balance, Cobb angle of LC, LIV position, postoperative LIV and LIV+1 tilt could be used to prognosticate LCC after STF. A model with solid prediction ability was established, which could further our understanding of LCC and assist in making clinical decisions.

Biomechanical effects of different instrumented segments and trunk shifts on distal adjacent segments after congenital scoliosis posterior hemivertebrectomy: Preliminary results of a single case

ObjectiveThe present study aims to discuss the biomechanical effects of the sagittal vertical axis and different instrumented segments on distal adjacent segments after congenital scoliosis posterior hemivertebrectomy. MethodA case of congenital scoliosis caused by hemivertebra was selected for the reconstruction of the preoperative and postoperative 3D computed tomography data of the full spine. A finite element model of different fusion lengths and postoperative trunk shift (TS) values was established using the finite element method to compare the biomechanical effects of different models on the distal adjacent segment. ResultIn the L1–L3 and T12–L1–L3–L4 fusion modes, the horizontal shift of the 1st vertebra below the lowest instrumented vertebra (LIV) increased with the trunk shift (TS) expansion after operation, and the imbalance between the left and right vertical stress of the 1st intervertebral disc below the LIV increased. With the decrease in fused segments in cases of TS = 10 mm and TS = 5 mm, the 1st vertebra below the LIV was subjected to a greater unbalanced force in the horizontal direction, and the 1st intervertebral disc below the LIV was subjected to a smaller imbalance between the left and right vertical stress after operation. ConclusionWhen treating congenital scoliosis with hemivertebrectomy and pedicle screw fixation, fused segments can be properly extended and the postoperative TS shortened with a view of reducing the imbalance between the left and right stress of the 1st intervertebral disc below the LIV as well as the horizontal shift of the 1st vertebra below the LIV.

Evaluation of crankshaft phenomenon after posterior fusion for early onset scoliosis using an inverse trigonometric function: a multicenter retrospective cohort study.

The crankshaft phenomenon (CSP) is a corrective loss after posterior surgery for early onset scoliosis (EOS). However, an accurate method for CSP evaluation has yet to be developed. In this study, we evaluated pedicle screw (PS) length and rotation angle using an inverse trigonometric function and investigated the prevalence of the CSP. Fifty patients from nine institutions (mean age 10.6years, male/female ratio 4:46) who underwent early definitive fusion surgery at ≤ 11years of age were included. The rotation angle was calculated as arctan (lateral/frontal PS length) using radiography. Measurements were taken at the apex and lower instrumented vertebra (LIV) immediate, 2-, and 5-year postoperatively. CSP was defined as a rotation angle progression ≥ 5°. We divided patients into CSP and non-CSP groups and measured the demographic parameters, Risser grade, state of the triradiate cartilage, major coronal Cobb angle, T1-T12 length, T1-S1 length, and presence of distal adding-on (DAO). We compared these variables between groups and investigated the correlation between the measured variables and vertebral rotation. Logistic regression analysis investigated factors associated with CSP. The rotation angle progressed by 2.4 and 1.3° over 5years for the apex and LIV, respectively. CSP occurred in 15 cases (30%), DAO in 11 cases (22%), and CSP and DAO overlapped in 4 cases (8%). In the CSP group, the T1-T12 length was low immediate postoperatively. The rotation angle was negatively correlated with preoperative height (r = -0.33), T1-T12 length (r = -0.35), and T1-S1 length (r = -0.30). A lower preoperative T1-T12 length was associated with CSP (odds ratio: 0.996, p = 0.048). CSP occurred in 30% of patients with EOS who underwent definitive fusion. The presence of CSP was associated with a lower preoperative T1-T12 length. Diagnosis, level IV.

The efficacy of anterior vertebral body tethering in lenke type 6 curves for adolescent idiopathic scoliosis.

Spinal fusion is the standard treatment for severe forms of adolescent idiopathic scoliosis (AIS). However, with the lowest instrumented vertebra that is usually located at L3 or L4, patients are prone to develop adjacent segment degeneration in the long term. Vertebral body tethering (VBT) as motion preserving technique has become an alternative for select patients with AIS. Several studies have presented the outcome after thoracic VBT but no study has analyzed the outcome after VBT for Lenke type 6 curves. This is a retrospective single center data analysis of patients who have had bilateral VBT for Lenke type 6 curves and a minimum follow up of 24months. Radiographic analysis was performed on several time points. Suspected tether breakages were additionally analyzed with respect to location and time at occurrence. 25 patients were included. Immediate thoracic curve correction was 55.4% and 71.7% for TL/L curves. Loss of correction was higher for TL/L curves and resulted in a correction rate of 48.3% for thoracic curves and 48.9% for TL/L curves at 24months post-operatively. 22 patients were suspected to have at least one segment with a tether breakage. Three patients required a re-VBT but no patient received posterior spinal fusion. Bilateral VBT for Lenke type 6 curves is feasible and shows a significant curve correction for thoracic and TL/L curves at a minimum of 24months post-operatively. Tether breakage rate and loss of correction remain an unfavorable observation that needs to be improved in the future.

The Clinical Significance of the Lowest Instrumented Vertebra in Adolescent Idiopathic Scoliosis.

Selecting the lowest instrumented vertebra (LIV) in fusion for adolescent idiopathic scoliosis is potentially the most nuanced decision a surgeon has to make. This article reviews the literature on the range-of-motion loss related to the LIV, ability to return to sports based on LIV, correlation between LIV and disk degeneration, and short-term and long-term clinical outcomes related to LIV.

Hyper-Selective Posterior Fusion is Recommended When the Modified S-Line is Positive in Lenke 5C Adolescent Idiopathic Scoliosis.

Postoperative coronal decompensation and less fusion level are dilemmas and the proper selective posterior fusion (SPF) strategy should be investigated. We proposed a parameter, modified S-line, and aimed to investigate if the modified S-line could predict postoperative coronal decompensation in patients with Lenke 5C adolescent idiopathic scoliosis (AIS). This is a retrospective radiographic study and Lenke 5C AIS patients undergoing SPF during the period from September 2017 to June 2021 were included. The modified S-line was defined as the line linking the centers of the concave-side pedicles of the upper end vertebra (UEV) and lower end vertebra (LEV) at baseline. A modified S-line tilt to the right is established as modified S-line+ (UEV being to the right of the LEV). The patients were further categorized into two groups: the Cobb to Cobb fusion group and the Cobb-1 to Cobb fusion group. Outcomes including thoracic Cobb angle, TL/L Cobb angle, coronal balance, upper instrumented vertebra (UIV) translation, lower instrumented vertebra (LIV) translation, UIV tilt, LIV tilt, LIV disc angle, thoracic apical vertebral translation, lumbar apical vertebral translation (L-AVT), L-T AVT ratio, L-T Cobb were measured at baseline, immediately after surgery, and the last follow-up. Radiographic parameters and the incidence of both proximal and distal decompensation between the two groups were compared by chi-square test. Among 92 patients, 48 were modified S-line+ and 44 were modified S-line-. Modified S-line+ status was identified as a risk factor for postoperative proximal decompensation (p = 0.005) during follow-up. In Cobb to Cobb group, a higher occurrence of proximal decompensation in individuals with modified S-line+ status (p = 0.001) was confirmed. Also, in the Cobb to Cobb group with baseline modified S-line+ status, patients presenting decompensation showed a significantly larger baseline of the UIV tilt and postoperative disc angle below the lower instrumented vertebra. However, In Cobb-1 group, the incidence of decompensation after surgery showed no association with baseline modified S-line tilt status (p = 0.815 and 0.540, respectively). The modified S-line could serve as an important parameter in surgical decision-making for Lenke 5C AIS patients. Cobb to Cobb SPF is not recommended with a modified S-line+ status, and the Cobb-1 to Cobb fusion may serve as a potential alternative.

Which lumbar vertebra should be the lowest level of fusion in adolescent idiopathic scoliosis of Lenke types 5 and 6?

It is important to protect the mobile segment in the lumbar region in scoliosis surgery. The aim of this study was to compare the clinical and radiological results of patients who underwent surgery for a diagnosis of adolescent idiopathic scoliosis (AIS) with the lowest instrumented vertebra (LIV) at L3 or L4 level. The study included 36 patients who underwent surgical treatment in our institution for a diagnosis of Lenke type 5 and 6 AIS with a follow-up period of at least 24 months. The patients were separated into 2 groups according to the LIV level of L3 (n=21) and L4 (n=15). These 2 groups were compared preoperatively (PO), early postoperative (EPO), and at the final follow-up examination (last control (LC)) with respect to radiological parameters in the coronal and sagittal planes, and the Scoliosis Research Society - 22 (SRS-22) questionnaire values. In both groups the mean age (L3: 16 ± 7.3; L4: 17 ± 6.1 years) and follow-up periods (L3: 44 ± 20; L4: 47 ± 18 months) were similar. Radiologically, the L4 group had a greater Cobb angle in the scoliosis main curves measured PO (P=.001). The Cobb angles measured at EPO (P=.767) and at LC (P=.674) were similar in both groups. No significant difference was observed between the 2 groups in respect of the LIV tilt values at PO (P=.469), EPO (P=.297), and LC (P=.065). When the groups were evaluated separately, the LIV tilt values at EPO and LC were similar in the L4 group (EPO: 6.93 ± 3.058; LC: 7.26 ± 2.313; P=.618). In the L3 patients, although there seemed to be a significant increase in LIV tilt values when EPO values were compared with LC values (EPO: 8.47 ± 3.970; LC: 9.57 ± 3.76; P=.030), this was within the error range of Cobb angle measurement. The results of the SRS-22 questionnaire showed significantly better results in the L3 group in the domains of pain, function/activity, mental health, and satisfaction with treatment (P=.011, P=.002, P=.019, P=.046, respectively). There was no radiological superiority between L3 and L4 LIV groups in the thoracolumbar/lumbar curve patients. However, according to the SRS-22 questionnaire, the results of patients with L3 level LIV were better in the areas of pain, function/activity, mental health, and satisfaction with treatment. Cite this article as:Baymurat AC, Tokgoz MA, Abdulaliyev F, Tosun MF, Can MM, Senkoylu A. Which lumbar vertebra should be the lowest level of fusion in adolescent idiopathic scoliosis of Lenke types 5 and 6? Acta Orthop Traumatol Turc., 2024;58(2):116-123.