Upper Instrumented Vertebra Research Articles

How do spine instrumentation parameters influence the 3D correction of thoracic adolescent idiopathic scoliosis? A patient-specific biomechanical study

BackgroundPatient-specific models promises to support the surgical decision-making process, particularly in adolescent idiopathic scoliosis. The present computational biomechanical study investigates how specific instrumentation parameters impact 3D deformity correction in thoracic scoliosis. Methods1080 instrumentation simulations of a representative patient were run. The independent instrumentation parameters were: screw pattern, upper and lower instrumented vertebrae, rod curvature and rod stiffness. ANOVA and correlation analyses analyzed how the instrumentation parameters influenced the 3D correction. FindingsCoronal plane correction was affected by the lower instrumented vertebra and rod stiffness (explaining 84% and 11%, respectively, of its overall variance). The sagittal profile was controlled by rod curvature and the upper vertebra (56% and 36%). The transverse plane vertebral rotation was influenced by lower, upper instrumented vertebra and screw pattern (35%, 32% and 19%). The Cobb angle correction was strongly correlated with the number of fused vertebrae, particularly when grouped by the upper instrumented vertebra (r = −0.91) and rod stiffness (r = −0.73). Thoracic kyphosis was strongly correlated with the number of fused vertebrae grouped by rod curvature (r = 0.84). Apical vertebral rotation was moderately correlated with the number of fused vertebrae grouped by upper/lower instrumented vertebra (r = 0.55/0.58), although variations were minimal. InterpretationInstrumenting the last vertebra touching the central sacral vertical line improves 3D correction. A trade-off between a more cranial vs. caudal upper instrumented vertebra, respectively beneficial for coronal/sagittal vs. transverse plane correction, is required. High rod stiffness, differential rod contouring, and screw pattern were effective for coronal correction, thoracic kyphosis, and axial vertebral derotation, respectively.

Intra operative assessment of the coronal balance in spinal deformity surgery : a technical note and retrospective study

Obtaining a spine that is well balanced after fusion for scoliotic deformity is primordial for the patients' quality of life. A simple T-shaped instrument combined with standard intraoperative fluoroscopy can be of great help to evaluate the coronal alignment quickly. The aim of this study was to evaluate if a T-shaped device could predict the postoperative coronal balance. Before finalization of the rod fixation, the balance was checked by verifying the relationship between the T-shaped instrument and the upper instrumented vertebra (UIV), and final adjustments were made to correct the coronal balance. A retrospective study was conducted on 48 patients who underwent surgery to correct scoliotic deformity. Intraoperative and postoperative coronal alignment was measured independently by two observers. The mean intraoperative horizontal offset measured between T-shaped instrument and the center of the UIV was 1,69mm to the right with a standard deviation (SD) of 12,43 mm. On postoperative full spine radiographs, the mean offset between the centra sacral vertical line and the center of the UIV was 2,44mm to the left with a SD of 13,10mm. There is no significant difference in coronal balance between both measurements (p=0,12). With this technique we were able to predict the postoperative coronal balance in all but one patient (97,92%). We conclude that the use of a simple T-shaped instrument can provide adequate intraoperative assessment of coronal balance in correcting scoliotic deformity. Level of evidence : IV - case series.

Caudally directed upper-instrumented vertebra pedicle screws associated with minimized risk of proximal junctional failure in patients with long posterior spinal fusion for adult spinal deformity

BACKGROUND CONTEXTIt is unknown whether upper instrumented vertebra (UIV) pedicle screw trajectory and UIV screw-rod angle are associated with development of proximal junctional kyphosis (PJK) and/or proximal junctional failure (PJF). PURPOSETo determine whether (1) the cranial-caudal trajectory of UIV pedicle screws and (2) UIV screw-vertebra angle are associated with PJK and/or PJF after long posterior spinal fusion in patients with adult spinal deformity (ASD). STUDY DESIGN/SETTINGRetrospective review. PATIENT SAMPLEWe included 96 patients with ASD who underwent fusion from T9–T12 to the pelvis (>5 vertebrae fused) between 2008 and 2015. OUTCOME MEASURESPedicle screw trajectory was measured as the UIV pedicle screw–vertebra angle (UIV-PVA), which is the mean of the two angles between the UIV superior endplate and both UIV pedicle screws. (Positive values indicate screws angled cranially; negative values indicate screws angled caudally.) We measured UIV rod-vertebra angle (UIV-RVA) between the rod at the point of screw attachment and the UIV superior endplate. METHODSDuring ≥2-year follow-up, 38 patients developed PJK, and 28 developed PJF. Mean (± standard deviation) UIV-PVA was −0.9° ± 6.0°. Mean UIV-RVA was 87° ± 5.2°. We examined the development of PJK and PJF using a UIV-PVA/UIV-RVA cutoff of 3° identified by a receiver operating characteristic curve, while controlling for osteoporosis, age, sex, and preoperative thoracic kyphosis. RESULTSPatients with UIV-PVA ≥3° had significantly greater odds of developing PJK (odds ratio 2.7; 95% confidence interval: 1.0–7.1) and PJF (odds ratio 3.6; 95% confidence interval: 1.3–10) compared with patients with UIV-PVA <3°. UIV-RVA was not significantly associated with development of PJK or PJF. CONCLUSIONSIn long thoracic fusion to the pelvis for ASD, UIV-PVA ≥3° was associated with 2.7-fold greater odds of PJK and 3.6-fold greater odds of PJF compared with UIV-PVA <3°. UIV-RVA was not associated with PJK or PJF. LEVEL OF EVIDENCEIII

Optimizing the fusion level for lenke 5C adolescent idiopathic scoliosis: is the S-line a validated and reproducible tool to predict coronal decompensation?

To validate the predictability of S-line in Lenke 5C patients. Lenke 5C patients with a minimum 2-year follow-up and with the lowest instrumented vertebra (LIV) at lower end vertebra were included. The S-line was defined as a line connecting the centers of concave-side pedicles of upper instrumented vertebra (UIV) and LIV on baseline films. The S-line tilt to right was defined as positive S-line status (S-line +) and tilt to left as S-line - status. Statistical analysis was performed between different subgroups. Among the 92 patients, 69 patients had a left lumbar curve and 23 patients had a right lumbar curve. For left curves, the S-line + status had a significantly higher incidence of both proximal and distal decompensation. However, for right curves, the S-line - status was the risk factor. Thus, we modified the definition of S-line: The value of S-line tilt for right curves was opposite to that for left curves. Patients with modified S-line + showed a significantly higher incidence of both proximal and distal decompensation in Lenke 5C patients with both left and right curves (p < 0.001 and p = 0.010). In UEV group, patients with modified S-line + showed significantly higher incidence of proximal decompensation (P = 0.001). However, in UEV-1 group, the incidence of proximal decompensation was not statistically affected by modified S-line + (P = 0.281). Modified S-line + is a validated risk factor that predisposed to post-operative coronal decompensation in Lenke 5C AIS patients. Selecting UIV at one level caudal to UEV could be a possible solution if the modified S-line was positive.

Risk Factors of Postoperative Shoulder Imbalance in Adolescent Idiopathic Scoliosis: The Role of Sagittal Spinopelvic Parameters and Upper Instrumented Vertebrae Selection.

This is a retrospective study. To determine (1) the independent risk factors of postoperative shoulder imbalance (PSI) after adolescent idiopathic scoliosis (AIS) correction surgery; and (2) whether the level of upper instrumented vertebrae (UIV) affects postoperative shoulder balance. PSI is an important outcome of AIS correction surgery as it influences a patient's appearance and satisfaction. However, risk factors for PSI remain controversial and there are currently no studies evaluating the effect of sagittal spinopelvic parameters on PSI. Previous studies on the relationship between the level of UIV and PSI have also reported conflicting results. Sixty-nine AIS patients undergoing correction surgery at a single institution were retrospectively reviewed. Radiographic parameters were measured on anteroposterior and lateral x-rays preoperatively, immediate postoperatively, and 12 months postoperatively. At 1 year follow-up, patients were divided into 2 groups based on their radiographic shoulder height (RSH): (1) PSI group (RSH ≥20 mm) and (2) non-PSI group (RSH <20 mm). On multivariate regression analysis, a lower postoperative main thoracic curve (MTC) [odds ratio (OR): 0.702, 95% confidence interval (CI): 0.519-0.949, P=0.022], greater percentage correction of MTC (OR: 1.526, 95% CI: 1.049-2.220, P=0.027) and higher postoperative sacral slope (OR: 1.364, 95% CI: 1.014-1.834, P=0.040) were identified as independent risk factors of PSI. When preoperative, postoperative, and absolute change in shoulder parameters were compared across the level of UIV, no significant differences were found regardless of the radiographic shoulder parameter analyzed. Lower postoperative MTC, greater percentage correction of MTC and higher postoperative sacral slope were independent risk factors of PSI. Shoulder balance and symmetry were not affected by the level of UIV selected. Relative curve correction is a more important consideration than UIV to avoid PSI after AIS correction surgery. III.

Proximal Fusion Level Above First Coronal Reverse Vertebrae: An Essential Factor Decreasing the Risk of Adjacent Segment Degeneration in Degenerative Lumbar Scoliosis.

Retrospective radiological analysis. To explore whether proximal fusion level above first coronal reverse vertebrae (FCRV) could decrease risk of adjacent segment degeneration (ASD) in degenerative lumbar scoliosis (DLS). One hundred and 16 DLS patients were divided into 2 groups according to occurrence of ASD: study group (ASD positive group) and control group (ASD negative group). FCRV was defined as the first vertebrae that presents opposite orientation of asymmetric Hounsfield unit (HU) ratio from the other vertebrae within major curve. Incidence of ASD was evaluated in subgroups according to location between FCRV and upper instrumented vertebrae (UIV). The fusion level was shorter in study group than that in control group. There were 12 patients presented FCRV 2-level proximal than SV, 32 patients presented FCRV 1-level proximal than SV, 35 patients presented the same vertebra of FCRV with SV, 23 patients presented FCRV 1-level distal than SV, 14 patients presented FCRV 2-level distal than SV. When UIV located above FCRV, no patient presented ASD, while 15.4% patients presented ASD when UIV located on FCRV. In study group, proximal scoliosis progression was detected in 1 patient (3.9%) when UIV located on FCRV, and 17 patients (29.8%) when UIV located below FCRV. Proximal fusion level above FCRV could decrease the risk of ASD in DLS, especially for the proximal scoliosis progression. FCRV represent the transitional point of the mechanical load on coronal plane, and may be within a more stable condition than stable vertebrae measured from radiographs.

Rod contour and overcorrection are risk factors of proximal junctional kyphosis after adult spinal deformity correction surgery.

To examine the risk factors of proximal junctional kyphosis (PJK) after surgery for adult spinal deformity (ASD) focusing on rod contour. Sixty-three patients with ASD who underwent surgery using lateral lumbar interbody fusion and percutaneous pedicle screws were analyzed. Fixation range was from the lower thoracic spine to the pelvis in all cases. Patients were divided into two groups. The PJK group consisted of 16 patients with PJK. The non-PJK group had 47 patients without PJK. We examined various spinopelvic parameters and parameters related to rod contour. Among the various spinal and pelvic parameters, those in the PJK group were significantly larger in terms of preoperative SVA and were significantly smaller in terms of postoperative "PI-LL." For parameters related to rod contour, the rod kyphotic curve at the thoracic spine in the PJK group was significantly less than that in the non-PJK group. The inclination of the pedicle screw at the upper instrumented vertebra (UIV) was significantly more cranial in the PJK group than in the non-PJK group. The kyphotic curve of the rod at the UIV was more parallel in the PJK group than in the non-PJK group. On logistic regression analysis, insufficient kyphotic curve at the thoracic spine along with UIV and overcorrection of the lumbar spine were identified as significant risk factors. Insufficient kyphotic curve of the rod in the thoracic spine along with UIV and overcorrection of the lumbar spine were noted as significant risk factors of PJK.

Correlation of vertebral trabecular attenuation in Hounsfield units and the upper instrumented vertebra with proximal junctional failure after surgical treatment of degenerative lumbar disease.

The aim of this study was to investigate whether bone mineral density (BMD) measured in Hounsfield units (HUs) is correlated with proximal junctional failure (PJF). A retrospective study of 104 patients with adult degenerative lumbar disease was performed. All patients underwent posterior instrumented fusion of 4 or more segments and were followed up for at least 2 years. Patients were divided into two groups on the basis of whether they had mechanical complications of PJF. Age, sex ratio, BMI, follow-up time, upper instrumented vertebra (UIV), lower instrumented vertebra, and vertebral body osteotomy were recorded. The spinopelvic parameters were measured on early postoperative radiographs. The HU value of L1 trabecular attenuation was measured on axial and sagittal CT scans. Statistical analysis was performed to compare the difference of continuous and categorical variables. Receiver operating characteristic (ROC) curve analysis was used to obtain attenuation thresholds. A Kaplan-Meier curve and log-rank test were used to analyze the differences in PJF-free survival. Multivariate analysis via a Cox proportional hazards model was used to analyze the risk factors. The HU value of L1 trabecular attenuation in the PJF group was lower than that in the control group (p < 0.001). The spinopelvic parameter L4-S1 lordosis was significantly different between the groups (p = 0.033). ROC curve analysis determined an optimal threshold of 89.25 HUs (sensitivity = 78.3%, specificity = 80.2%, area under the ROC curve = 0.799). PJF-free survival significantly decreased in patients with L1 attenuation ≤ 89.25 HUs (p < 0.001, log-rank test). When L1 trabecular attenuation was ≤ 89.25 HUs, PJF-free survival in patients with the UIV at L2 was the lowest, compared with patients with their UIV at the thoracolumbar junction or above (p = 0.028, log-rank test). HUs could provide important information for surgeons to make a treatment plan to prevent PJF. L1 trabecular attenuation ≤ 89.25 HUs measured by spinal CT scanning could predict the incidence of PJF. Under this condition, the UIV at L2 significantly increases the incidence of PJF.

Proximal junctional kyphosis after pediatric angular kyphotic deformity correction: Are we missing something?

Purpose:Corrective maneuvers in an angular kyphotic deformity have its own problems including early complications such as neurological deficit and late complications such as proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). This article discusses the probable mechanisms, leading to PJK in pediatric severe angular kyphotic deformities and preventive strategies for the same. We will also assess natural course of untreated PJK and its devastating consequences.Materials and Methods:Three patients, two 13-year males presented with progressive, painless thoracolumbar kyphoscoliotic deformity, with segmental kyphosis 100° and 140° and scoliosis of 33° and 78°, respectively, and one 14-year-old female presented with angular kyphotic deformity of 60° with apex at D11-12 level.Results:Posterior vertebral column resection with segmental deformity correction with good coronal and sagittal balance was done. In the follow-up, PJF was seen. Second surgery was done with the extension of instrumentation to D4 along with deformity correction in both the male patients. The female patient did not opt for a revision surgery, and we are following the natural history of this case.Conclusion:In severe thoracolumbar angular kyphotic deformities with normal or negative sagittal balance, it might be a safer option to select the sagittal stable vertebra as upper instrumented vertebra based on the C2 plumb line on the preoperative standing lateral radiographs. However, a study with a larger sample size is needed to validate our hypothesis.

Preoperative Thoracic Curve Magnitude and L4 End Vertebra Were Risk Factors for Subjacent Disc Wedging After Selective Thoracolumbar/Lumbar Fusion with L3 as the Lowest Instrumented Vertebra in Lenke Type 5 Curve Patients.

Retrospective multicenter study. This study aimed to investigate the incidence and risk factors of subjacent disc wedging (SDW) in adolescent idiopathic scoliosis (AIS) patients with Lenke type 5 curve. SDW is frequently observed after surgery; however, data about its mechanism and relations with outcome are limited. Data of 59 patients with AIS with Lenke type 5 curves who underwent posterior spinal fusion to L3 as the lowest instrumented vertebra (LIV) were retrospectively analyzed. The subjacent disc angle (SDA) was defined as the angle between L3 (LIV) and L4. SDW was defined as the absolute value of SDA of 10° or higher 2 years postoperatively. The incidence of SDW was investigated between nonselective and selective thoracolumbar/lumbar (TL/L) fusion group. In the selective group, patients with and without SDW were compared. Among 59 patients, 11 had nonselective and 48 had selective fusion. No patients in the nonselective group showed SDW versus 13 patients in the selective group (27%) showed SDW. In the selective group, patients with SDW showed significantly greater main thoracic curve, apical vertebral translation of the main thoracic curve, upper instrumented vertebra tilt, LIV tilt, and SDA 2 years postoperatively, whereas no differences were found in the coronal balance or clinical outcome. Multivariate analysis revealed preoperative T curve and SDA as predictors of SDW occurrence. T curve greater than 30° and SDA greater than 0° were calculated as cutoff values based on the receiver operating characteristic curve. SDW is sometimes seen in Lenke type 5 patients with AIS who underwent selective TL/L fusion. SDW seemed to occur as a compensation mechanism for progressing deformity of unfused segments (thoracic curve and residual lumbar curve) to maintain coronal alignment. Preoperative T curve > 30° and SDA > 0° (lower-end vertebra as L4) were determined as risk factors for SDW occurrence.Level of Evidence: 3.

Surgeons lack of agreement on determining preoperative radiographic and clinical shoulder balance in adolescent and adult idiopathic scoliosis patients.

Preoperative shoulder balance is an important factor in determining the upper instrumented vertebrae (UIV). In adolescent and adult idiopathic scoliosis (AIS/AdIS) patients, we studied the intraobserver and interobserver reliability of spinal surgeons' assessment of preoperative shoulder balance using X-rays (XR) and anterior/posterior photographs. An observational review of a prospective multicenter database (AIS Lenke Type 1/5/6) and prospective single-institution database (AdIS) was conducted. Ten spine surgeons reviewed AIS cases; 12 spine surgeons reviewed AdIS cases. Surgeons rated the higher shoulder: left/right/same/unsure. Reliability was calculated using Fleiss' kappa coefficient. Among 145 Type 1 AIS cases, intraobserver reliability was moderate-to-substantial: XR (κ = 0.59), anterior photographs (κ = 0.68), posterior photographs (k = 0.65). Interobserver reliability was fair to moderate for XR (κ = 0.31), anterior photographs (κ = 0.20), and posterior photographs (κ = 0.30). Among 52 Type 5/6 AIS cases, intraobserver reliability was substantial: XR (κ = 0.70), anterior photographs (κ = 0.76), posterior photographs (κ = 0.71). Interobserver reliability was fair to moderate for XR (κ = 0.49), anterior photographs (κ = 0.47), and posterior photographs (κ = 0.36). Among 66 AdIS cases, intraobserver reliability was substantial: XR (κ = 0.68), anterior photographs (κ = 0.67), posterior photographs (κ = 0.69). Interobserver reliability was moderate for XR (κ = 0.45), anterior photographs (κ = 0.43), posterior photographs (κ = 0.49). Within Type 1 AIS patients, attendings had better intraobserver reliabilities compared to fellows using X-rays (κ = 0.61 vs. 0.53), yet no effect of surgeon experience was seen with clinicalphotographs. Though surgeons' ability to agree with themselves was moderate to substantial, surgeons' ability to agree with each other was fair to moderate. Combined measures to assess preoperative shoulder balance are needed for UIV selection.

The effect of upper instrumented vertebra level (T9 vs T10) on radiologic and functional outcomes in the surgical treatment of adult spinal deformity in osteoporotic patients over 60 years of age

The effect of upper instrumented vertebra level (T9 vs T10) on radiologic and functional outcomes in the surgical treatment of adult spinal deformity in osteoporotic patients over 60 years of age

Sinister! The high pre-op left shoulder is less likely to be radiographically balanced at 2 years post-op.

AIS patients consider shoulder balance an important cosmetic outcome after surgery. We examined the impact of preoperative left shoulder elevation (LSE) and choice of upper instrumented vertebra (UIV) on postoperative shoulder imbalance (PostSI). This was a retrospective cohort study utilizing a prospective AIS database. Patients had Lenke type 1-4 curves and preoperative shoulder height ≥ 1.0cm. Patients with preoperative LSE and right shoulder elevation (RSE) were compared. Shoulder height difference < 1cm was considered 'mild', 1-2cm was 'moderate', and ≥ 2.0cm was 'severe'. 407 patients had ≥ 1.0cm imbalance preoperatively, with 88 (21.6%) LSE. There were no differences in gender (p = 0.855) or age (p = 0.477). Patients with LSE more frequently had Lenke type 2 curves (43.2% vs 16.3%, p < 0.001), while preoperative RSE averaged 1.9 ± 0.9cm versus 1.6 ± 0.5cm for LSE (p < 0.001). Those with LSE more often had severe PostSI at 2years (30.7% vs 5.0%, p < 0.001), and only 26.1% of patients with severe preoperative LSE corrected to mild. In contrast, most patients with RSE had mild PostSI regardless of initial imbalance. When examining only LSE patients, there was no difference in preoperative SH by final UIV (p = 0.101). Further, UIV choice did not impact the proportion of severely unbalanced patients postoperatively (p = 0.446). A PTC > 34.5° was predictive of PostSI ≥ 2.0cm for patients with preoperative LSE. AIS patients with preoperative LSE are less likely to achieve level shoulders postoperatively. Choice of higher UIV did not affect postoperative shoulder imbalance in this cohort. A PTC > 34.5° was predictive of severe PostSI in patients with preoperative LSE. II.

Preoperative Hounsfield Units at the Planned Upper Instrumented Vertebrae May Predict Proximal Junctional Kyphosis in Adult Spinal Deformity.

Retrospective cohort study. To investigate the association between Hounsfield units (HU) measured at the planned upper instrumented vertebra (UIV) and UIV+1 and proximal junctional kyphosis (PJK) in patients with adult spinal deformity (ASD). PJK is a common complication following surgery for ASD and poor bone quality is noted to be one of the risk factors. HUs from standard computed tomography (CT) scans can be used for evaluating regional bone quality. Sixty-three patients were included from a single institution. The demographic characteristics and radiographic parameters were recorded. Local vertebral HUs at the planned UIV and UIV+ 1 were measured using preoperative CT scans. The patients were divided into three groups: no PJK, non-bony PJK, and bony PJK. The risk factors between the three groups and the correlation between the mean HU and increase in the PJK angle were analyzed. The incidence of PJK was 36.5%. The mean HU was significantly lower in the bony PJK group (HU: 109.0) than in the no PJK group (HU: 168.7, P = 0.038), and the mean HU in the non-bony PJK group (HU: 141.7) was not different compared to the other two groups. There was a significant negative correlation between the mean HU values and the increase in the PJK angles (r = -0.475, P < 0.01). The cutoff value for the mean HU used to predict bony PJK was 120 and a HU value less than 120 was a significant risk factor for bony PJK (OR: 5.74, 95% CI [1.01-32.54], P = 0.04). We noted a significant inverse relationship between the mean HUs at the UIV and UIV+ 1 and increase in the PJK angles postoperatively. In ASD patients, the HUs may be used preoperatively to identify patients with a higher risk of bony PJK.Level of Evidence: 3.

Crossing the Cervicothoracic Junction During Posterior Cervical Fusion for Myelopathy Is Associated With Superior Radiographic Parameters But Similar Clinical Outcomes.

For laminectomy and posterior spinal fusion (LPSF) surgery for cervical spondylotic myelopathy (CSM), the evidence is unclear as to whether fusions should cross the cervicothoracic junction (CTJ). To compare LPSF outcomes between those with and without lower instrumented vertebrae (LIV) crossing the CTJ. A consecutive series of adults undergoing LPSF for CSM from 2012 to 2018 with a minimum of 12-mo follow-up were identified. LPSF with subaxial upper instrumented vertebrae and LIV between C6 and T2 were included. Clinical and radiographic outcomes were compared. A total of 79 patients were included: 46 crossed the CTJ (crossed-CTJ) and 33 did not. The mean follow-up was 22.2 mo (minimum: 12 mo). Crossed-CTJ had higher preoperative C2-7 sagittal vertical axis (cSVA) (33.3±16.0vs 23.8±12.4mm, P=.01) but similar preoperative cervical lordosis (CL) and CL minus T1-slope (CL minus T1-slope) (P > .05, both comparisons). The overall reoperation rate was 3.8% (crossed-CTJ: 2.2%vs not-crossed: 6.1%, P=.37). In adjusted analyses, crossed-CTJ was associated with superior cSVA (β = -9.7; P=.002), CL (β = 6.2; P=.04), and CL minus T1-slope (β = -6.6; P=.04), but longer operative times (β = 46.3; P=.001). Crossed- and not-crossed CTJ achieved similar postoperative patient-reported outcomes [Visual Analog Scale (VAS) neck pain, VAS arm pain, Nurick Grade, Modified Japanese Orthopedic Association Scale, Neck Disability Index, and EuroQol-5D] in adjusted multivariable analyses (adjusted P>.05). For the entire cohort, higher postoperative CL was associated with lower postoperative arm pain (adjusted Pearson's r -0.1, P=.02). No postoperative cervical radiographic parameters were associated with neck pain (P>.05). Subaxial LPSF for CSM that crossed the CTJ were associated with superior radiographic outcomes for cSVA, CL, and CL minus T1-slope, but longer operative times. There were no differences in neck pain or reoperation rate.

Semitendinosus Tendon Augmentation for Prevention of Proximal Junctional Failure.

Retrospective cohort study. The aim of this study was to compare the incidence of proximal junctional kyphosis (PJK), proximal junctional failure (PJF), and clinical outcomes of patients who did and did not receive posterior ligament complex (PLC) augmentation using a semitendinosus allograft when undergoing long-segment posterior spinal fusion for adult spinal deformity. Clinical research on the augmentation of the PLC to prevent PJK and PJF has been limited to small case series without a comparable control group. From 2014 to 2019, a consecutive series of patients with adult spinal deformity who underwent posterior long-segment spinal fusion with semitendinosus allograft to augment the PLC (allograft) or without PLC augmentation (control) were identified. Preoperative and postoperative spinopelvic parameters were measured. PJK, PJF, and Oswestry Disability Index (ODI) scores were recorded and compared between the two groups. Univariate and multivariate analysis was performed. P ≤ 0.05 was considered significant. Forty-nine patients in the allograft group and 34 patients in the control group were identified. There were no significant differences in demographic variables or operative characteristics between the allograft and control group. Preoperative and postoperative spinopelvic parameters were also similar between the two groups. PJK was present in 33% of patients in the allograft group and 32% of patients in the control group (P = 0.31). PJF did not occur in the allograft group, whereas six patients (18%) in the control group developed PJF (P = 0.01). Postoperative absolute ODI was significantly better in the allograft group (P = 0.007). The utilization of semitendinosus allograft tendon to augment the PLC at the upper instrumented vertebrae in patients undergoing long-segment posterior spinal fusion for adult deformity resulted in a significant decrease in PJF incidence and improved functional outcomes when compared to a cohort with similar risk of developing PJK and PJFLevel of Evidence: 3.

A Nomogram to Predict the Occurrence and Development of Postoperative Neck Tilt in Lenke I and II AIS Patients

To investigate the risk factors and to construct a nomogram for the prediction of postoperative neck tilt (PNT) in patients with Lenke I and II adolescent idiopathic scoliosis (AIS). A total of 95 patients with Lenke I and II AIS who underwent posterior segmental spinal instrumentation and fusion between the years 2010 and 2018 (with an average 2-year follow-up) at a single institution were retrospectively investigated. The full spine X-rays of patients were measured preoperatively, postoperatively, and at the final follow-up. Variables were compared between the PNT group (n= 33) and the non-PNT group (n= 62), and univariate and multivariate logistic regressions were performed to identify the independent predictors for the occurrence of PNT. The discrimination and calibration of the nomogram were validated by the receiver operating characteristic curve and calibration curve. Variables including the preoperative neck tilt, postoperative upper instrumented vertebrae imbalance, postoperative T1 tilt, and decreasing values in the main thoracic curve (ΔMTC) minus decreasing values in the proximal thoracic curve (ΔPTC) (ΔMTC- ΔPTC) were identified as the predictors for the nomogram. The area under the receiver operating characteristic curve was 0.900 (95% confidence interval, 0.857-0.932). Meanwhile, the calibration curve revealed good agreement, and the Hosmer and Lemeshow test determined that the model was well fitted. Preoperative neck tilt, postoperative upper instrumented vertebrae imbalance, postoperative T1 tilt, and ΔMTC-ΔPTC are predictors for the nomogram. The nomogram can provide surgeons with a simple and effective tool to predict the occurrence and development of patients with PNT in Lenke I and II AIS.

Comparison of Proximal Junctional Failure and Functional Outcomes Across Varying Definitions of Proximal Junctional Kyphosis

Proximal junctional kyphosis (PJK) is a well-recognized complication following surgery for adult spinal deformity (ASD); however, definitions for PJK and its clinical implications can significantly vary by study. This study compares multiple definitions of PJK and describes incidence and clinical significance by definition. From 2014 to 2019, patients with ASD who underwent spinal fusion were identified. Nine definitions of PJK were created based on previously established definitions using the following upper instrumented vertebra+2 (UIV+2) sagittal Cobb measurements: A= ≥10 postoperative AND preoperative, B= ≥10 postoperative, C=≥10 preoperative, D= ≥15 postoperative AND preoperative, E= ≥15 postoperative, F= ≥15 preoperative, G= ≥20 postoperative AND preoperative, H= ≥20 postoperative, I= >20 preoperative. Incidence of PJK was calculated by definition. Area under the curve (AUC) was calculated based on a receiver operating characteristic to assess ability to predict proximal junctional failure (PJF). Univariate analysis was performed to assess association with postoperative Oswestry Disability Index (ODI) scores. Across 82 patients, the incidence of PJK and AUC by definition was as follows: A= 47%, 0.47; B= 72%, 0.65; C= 49%, 0.45; D= 27%, 0.46; E= 57%, 0.62; F=27%, 0.46; G= 10%, 0.55; H= 40%, 0.71; I= 10%, 0.55. No definition was associated with postoperative ODI scores (P < 0.05). The incidence of PJK significantly decreased with stricter definitions. Definitions utilizing only postoperative UIV+2 values had higher incidences but were more likely to capture patients who developed PJF. No definition was associated with postoperative ODI scores. UIV+2 ≥20 was best in distinguishing patients who developed PJF.

Predictive Model for Selection of Upper Treated Vertebra Using a Machine Learning Approach

To train and validate an algorithm mimicking decision making of experienced surgeons regarding upper instrumented vertebra (UIV) selection in surgical correction of thoracolumbar adult spinal deformity. A retrospective review was conducted of patients with adult spinal deformity who underwent fusion of at least the lumbar spine (UIV > L1 to pelvis) during 2013-2018. Demographic and radiographic data were collected. The sample was stratified into 3 groups: training (70%), validation (15%) and performance testing (15%). Using a deep learning algorithm, a neural network model was trained to select between upper thoracic (T1-T6) and lower thoracic (T7-T12) UIV. Parameters used in the deep learning algorithm included demographics, coronal and sagittal preoperative alignment, and postoperative pelvic incidence-lumbar lordosis mismatch. The study included 143 patients (mean age 63.3 ± 10.6 years, 81.8% women) with moderate to severe deformity (maximum Cobb angle: 43° ± 22°; T1 pelvic angle: 27° ± 14°; pelvic incidence-lumbar lordosis mismatch: 22° ± 21°). Patients underwent a significant change in lumbar alignment (Δpelvic incidence-lumbar lordosis mismatch: 21° ± 16°, P < 0.001); 35.0% had UIV in the upper thoracic region, and 65.0% had UIV in the lower thoracic region. At 1 year, revision rate was 11.9%, and rate of radiographic proximal junctional kyphosis was 29.4%. Neural network comprised 8 inputs, 10 hidden neurons, and 1 output (upper thoracic or lower thoracic). After training, results demonstrated an accuracy of 81.0%, precision of 87.5%, and recall of 87.5% on testing. An artificial neural network successfully mimicked 2 lead surgeons' decision making in the selection of UIV for adult spinal deformity correction. Future models integrating surgical outcomes should be developed.

Risk factors for postoperative coronal decompensation in adult lumbar scoliosis after posterior correction with osteotomy.

To determine potential risk factors for postoperative coronal imbalance following posterior osteotomy for adult scoliosis. A total of 74 patients underwent osteotomy for rigid adult lumbar scoliosis. A group of 20 patients with postoperative coronal imbalance was identified. Clinical data and surgical strategies were compared to determine the risk factors, including age, gender, etiology, Cobb angle, preoperative coronal balance distance, direction of preoperative imbalance, T1 tilt, tilt of upper instrumented vertebra (UIV), UIV translation, location of UIV (T6 above or below), fusion to L5 or S1, lower instrumented vertebra (LIV) tilt, LIV rotation, screw density, osteotomy procedure (PSO or SPOs) and use of iliac screws. Comparison between patients with and without postoperative coronal imbalance showed that postoperative coronal imbalance occurred in older patients and those with degenerative scoliosis as the etiology, UIV above T6, preoperative LIV rotation, preoperative LIV tilt and preoperative coronal imbalance towards the convex side and who underwent Smith-Petersen osteotomy. All seven parameters were included in the logistic regression analysis. UIV above T6 (P = 0.010), LIV rotation (P = 0.012) and preoperative coronal imbalance towards the convex side (P = 0.005) were identified as risk factors for postoperative coronal imbalance after osteotomy. Patients with preoperative coronal imbalance towards the convex side (UIV above T6) and LIV rotation were more likely to develop coronal imbalance than those without risk factors. Older patients and those with degenerative scoliosis were also at a relatively higher risk of postoperative coronal imbalance.