non-PJK Group Research Articles

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°.

Simplified S1 vertebral bone quality score independently predicts proximal junctional kyphosis after surgery for degenerative lumbar scoliosis

ObjectiveOur study aimed to assess the effectiveness of the simplified S1 vertebral bone quality (VBQ) score in predicting the incidence of proximal junctional kyphosis (PJK) after surgery for degenerative lumbar scoliosis (DLS).MethodsWe reviewed 122 patients with DLS who underwent posterior lumbar decompression and long-segment fusion surgery in our hospital from January 2016 to December 2020. The patients were classified into PJK group and non-PJK group. S1 VBQ scores are determined by signal intensity measurements taken from the mid-sagittal plane of T1-weighted non-contrast MRI. Logistic regression analysis was used to identify factors associated with PJK. Receiver-operating characteristic curve (ROC) analysis was used to evaluate the value of S1 VBQ score in predicting pedicle PJK after DLS.Results122 DLS patients (90 females and 32 males) met the inclusion criteria. In addition, 27 patients (22.13%) had PJK at the time of last follow-up. VBQ was higher in PJK patients than non-PJK patients (3.58 ± 0.67 vs. 3.08 ± 0.54, p < 0.001). Preoperatively, patients in the PJK group had a greater TLK than those in the non-PJK group (20.00 ± 6.22 vs. 16.86 ± 5.38, p = 0.011). After surgery, patients in the PJK group had greater TLK (p < 0.001) and PJA (p < 0.001) compared with the non-PJK group. At final FU, patients in the PJK group had greater TK (p = 0.002), TLK (p < 0.001), SVA (p < 0.001), and PJA (p < 0.001) than patients in the non-PJK group (Table 4). In multivariate logistic regression analysis, higher VBQ score (OR 4.565, 95% CI 1.43–14.568, p = 0.010), advanced age (OR 1.119, 95% CI 1.021–1.227, p = 0.016), and larger TLK (OR 1.191, 95% CI 1.041–1.362, p = 0.011) were significant predictors of postoperative PJK in patients with DLS (Table 6). A statistically significant positive correlation existed between VBQ score and PJA change (r = 0.370, p < 0.001). We created ROC curves for VBQ scores as predictors of PJK with a diagnostic accuracy of 72.1% (95% CI 60.15–82.9%.The ideal limit for the VBQ score was 3.205 (sensitivity: 77.8%, specificity: 81.4%).ConclusionTo the best of our knowledge, this is the first study to evaluate the effectiveness of the S1 VBQ score in predicting postoperative PJK in DLS. Our study included major risk factors and found that S1 VBQ score was a significant predictor of PJK in patients undergoing DLS surgery. The higher the S1 VBQ score, the higher the probability of PJK.

Simplified S1 vertebral bone quality (vbq) score to assess proximal junctional kyphosis after Lenke 5 adolescent idiopathic scoliosis surgery.

Proximal junctional kyphosis (PJK) is a common complication following corrective surgery for adolescent idiopathic scoliosis (AIS) with a Lenke 5 curve. Previous studies have suggested that PJK may be associated with osteopenia, which is prevalent in AIS patients. MRI-based vertebral bone quality (VBQ) scores have been proposed as a valuable tool to assess preoperative bone quality. However, accurately measuring VBQ scores in Lenke 5 AIS patients with a structural lumbar curve can be challenging. Recently, a simplified S1 VBQ score has been proposed as an alternative method when the traditional VBQ score is not applicable. This study aims to evaluate the predictive value of the simplified S1 VBQ score in predicting the occurrence of PJK after corrective surgery for Lenke 5 AIS. We conducted a retrospective analysis of patient data to assess the predictive utility of the S1 VBQ score for PJK in Lenke 5 AIS patients. Demographic, radiographic, and surgical data were collected, and S1 VBQ scores were calculated based on preoperative T1-weighted MRI images. Univariate analysis, linear regression, and multivariate logistic regression were performed to identify potential risk factors for PJK and to assess the correlation between other variables and the S1 VBQ score. Receiver operating characteristic analysis and area under the curve values were used to evaluate the predictive efficiency of the S1 VBQ score for PJK. A total of 105 patients (aged 15.50 ± 2.36years) were included in the analysis, of whom 24 (22.9%) developed PJK. S1 VBQ scores were significantly higher in the PJK group compared to the non-PJK group (2.83 ± 0.44 vs. 2.48 ± 0.30, P < 0.001), and there was a significant positive correlation between the S1 VBQ score and proximal junctional angle (PJA) (r = 0.46, P < 0.0001). Multivariate analysis revealed that the S1 VBQ scores and preoperative thoracic kyphosis (TK) were significant predictors of PJK. This study provided evidence that higher S1 VBQ scores were independently associated with PJK occurrence following corrective surgery for Lenke 5 AIS. Preoperative measurement of the S1 VBQ score on MRI may serve as a valuable tool in planning surgical correction for Lenke 5 AIS.

Restoring the ideal Roussouly sagittal alignment in Lenke 5 adolescent idiopathic scoliosis patients: a method for decreasing the risk of proximal junctional kyphosis.

Although the Roussouly classification has been widely used in surgical planning for adult scoliosis patients, little is known about whether it can be used to guide sagittal correction for adolescent idiopathic scoliosis (AIS) patients. The purpose of this study was to explore whether the Roussouly classification could be used to help surgeons restore the ideal sagittal alignment for AIS patients to avoid the development of proximal junctional kyphosis (PJK). In this retrospective cohort study, eighty-seven patients with Lenke 5 AIS who underwent surgery from January 2010 to August 2020 were enrolled and divided into two groups: the PJK group and the non-PJK group. All patients were classified into "current types" and "ideal types" according to two versions of the Roussouly classification, and the mismatch rate was evaluated in terms of the consistency between their current type and ideal type. Student's t test, Mann‒Whitney U test, Pearson's Chi-square test, and others were used to compare the two groups regarding patient demographic characteristics (age, sex, Risser sign, etc.) and radiographic parameters (sagittal vertical axis [SVA]; thoracic kyphosis [TK]; thoracolumbar junctional kyphosis [TLK]; lumbar lordosis [LL]; pelvic incidence [PI]; pelvic tilt [PT]; sacral slope [SS]; upper instrumented vertebra [UIV]; lower instrumented vertebra [LIV]; etc.). Multivariate logistic regression with backwards stepwise selection was performed to identify the risk factors for PJK. PJK was observed in 16 out of 87 patients (18.4%) until the final follow-up. The incidence of PJK was significantly higher in the patients not matching their ideal type than in those who did after surgery (60.9% vs. 3.1%, p = 0.000). The patients with ideal Type 1 had the highest incidence of PJK, while the lowest incidence was observed in patients with ideal Type 2 (50.0% vs. 5.1%, p = 0.000). The PJK group had greater TK, LL, and PI-LL than the non-PJK group before and after surgery. The postoperative PJA in the PJK group was also larger than that in the non-PJK group. Multivariate logistic regression revealed that postoperative Roussouly type mismatch was significantly associated with the occurrence of PJK (OR = 64.2, CI = 9.6-407.1, p = 0.000). The Roussouly classification could serve as a prognostic tool for PJK in Lenke 5 AIS patients. Corrective surgery should restore sagittal alignment with respect to the patient's ideal sagittal profile (according to the Roussouly classification based on the PI) to decrease the incidence of PJK in AIS patients.

Analysis of factors associated with proximal junctional kyphosis after surgery for Lenke type 5 adolescent idiopathic scoliosis

Objective: To investigate the risk factors associated with the development of proximal junctional kyphosis (PJK) after posterior spinal fusion for in children with Lenke type 5 adolescent idiopathic scoliosis (AIS). Methods: It was a retrospective case-control study that included medical records of 98 children with Lenke type 5 AIS who underwent posterior orthopedic surgery under general anesthesia at the Honghui Hospital Affiliated to Xi'an Jiaotong University from January 2013 to December 2018. There were 23 males and 75 females with a mean age of (14.5±2.2) years (10-18 years). Patients were divided into PJK and non-PJK groups according to whether the posterior junctional angle (PJA) was greater than 10° and increased for more than 10° from the preoperative period at the the last follow-up. Univariate analysis was used to analyze the correlation of general data of the children with occurrence of PJK after the operation. Multivariate logistic regression analysis was used to analyze the risk factors of postoperative PJK. Results: There were 35 cases in the PJK group and 63 cases in the non-PJK group. The PJK and non-PJK groups were followed up for (35.6±7.3) months and (36.4±7.5) months, respectively, and the difference was not statistically significant (P=0.637). There was no statistically significant difference between the two groups in general data such as gender, age, and body mass index (all P>0.05), while there were statistically significant differences between the two groups in upper instrumented vertebrea (UIV) location and junctional area posterior ligamentous complex (PLC) injury (all P<0.05). The results of univariate analysis showed that UIV location at T10-T12, junctional area PLC injury, preoperative coronal thoracic curve (TC), preoperative and final follow-up PJA, and preoperative and final follow-up pelvic incidence-lumbarlordosis (PI-LL) were correlated with postoperative PJK (OR=2.50, 5.37, 0.92, 1.12, 1.32, 1.06, 3.35, all P<0.05). Multifactorial logistic regression analysis showed that UIV located at T10-T12 (OR=2.346, 95%CI: 1.582-3.481, P=0.001), junctional area PLC injury (OR=5.112, 95%CI: 1.283-20.418, P=0.023) and last follow-up PI-LL (OR=1.826, 95%CI: 1.558-24.745, P=0.012) were risk factors for the occurrence of postoperative PJK in children with Lenke type 5 AIS. Conclusions: Postoperative UIV fixation to the thoracolumbar segment, PLC injury in the junctional area and excessive postoperative PI-LL in children with Lenke type 5 AIS may be the risk factors for the occurrence of PJK after the operation. It is suggested that avoidance of UIV selection to the thoracolumbar segment, intraoperative protection of the PLC located near the UIV and restoration of a good PI-LL relationship may reduce the incidence of PJK.

The Role of Thoracic Tilt in Identifying Thoracic Compensation and Predicting Proximal Junctional Kyphosis in Degenerative Lumbar Scoliosis.

A retrospective cohort study of consecutive patients. To investigate the clinical value of thoracic tilt (TT) in characterizing thoracic compensation and predicting proximal junctional kyphosis (PJK) in degenerative lumbar scoliosis (DLS). Thoracic compensation has been shown to be associated with the development of PJK, while thoracic shape and morphology in patients with DLS remain understudied. Patients with DLS who underwent long-segment fusion were divided into a PJK group and a non-PJK group. Asymptomatic elderly volunteers were recruited as healthy controls. Thoracic parameters were measured in both cohorts, including the TT, T1-L1 pelvic angle (TLPA), T12 slope, thoracic kyphosis (TK, T4-T12), global thoracic kyphosis (GTK, T1-T12), and thoracolumbar kyphosis (TLK, T10-L2). Multivariate logistic regression was used to assess the association between TT and the development of PJK, adjusting for confounders. Multivariate linear regression was used to establish the predictive formula for TT. A total of 126 patients with DLS were enrolled, of which 37 (29.4%) developed PJK. Compared with 110 healthy controls, DLS patients had significantly greater TT, TLPA, T12 slope, and TLK as well as smaller TK and GTK (all P <0.001). Preoperatively, the PJK group showed significantly greater TT ( P =0.013), TLPA ( P <0.001), and TLK ( P =0.034) than the non-PJK group. No significant differences were found in TK and GTK before surgery. Postoperatively, the PJK group showed significantly greater TT ( P <0.001), TLPA ( P <0.001), TLK ( P <0.001), and proximal junctional angle ( P <0.001). Multivariate logistic regression analysis showed that greater postoperative TT was associated with the development of PJK. Multivariate linear regression analysis suggested that the regression formula was postoperative TT=0.675×T12slope+0.412×TK+0.158×TLK-4.808 ( R2 =0.643, P <0.001). The novel sagittal parameter TT can be used for the evaluation of thoracic compensation. Greater preoperative TT might represent a decompensated state of TK. Rebalancing the TT in a sagittal neutral position might help to prevent PJK in patients with DLS.

Application of back-forward Bending CT localization image in the prediction of proximal junctional kyphosis after spinal deformity surgery in adults

To investigate the feasibility of predicting proximal junctional kyphosis (PJK) in adults after spinal deformity surgery based on back-forward Bending CT localization images and related predictive indicators. A retrospective analysis was performed for 31 adult patients with spinal deformity who underwent posterior osteotomy and long-segment fusion fixation between March 2017 and March 2020. There were 5 males and 26 females with an average age of 62.5 years (range, 30-77 years). The upper instrumented vertebrae (UIV) located at T 5 in 1 case, T 6 in 1 case, T 9 in 13 cases, T 10 in 12 cases, and T 11 in 4 cases. The lowest instrumented vertebrae (LIV) located at L 1 in 3 cases, L 2 in 3 cases, L 3 in 10 cases, L 4 in 7 cases, L 5 in 5 cases, and S 1 in 3 cases. Based on the full-length lateral X-ray film of the spine in the standing position before and after operation and back-forward Bending CT localization images before operation, the sagittal sequence of the spine was obtained, and the relevant indexes were measured, including thoracic kyphosis (TK), lumbar lordosis (LL), local kyphosis Cobb angle (LKCA) [the difference between the different positions before operation (recovery value) was calculated], kyphosis flexibility, hyperextension sagittal vertical axis (hSVA), T 2-L 5 hyperextension C 7-vertebral sagittal offset (hC 7-VSO), and pre- and post-operative proximal junctional angle (PJA). At last follow-up, the patients were divided into PJK and non-PJK groups based on PJA to determine whether they had PJK. The gender, age, body mass index (BMI), number of fusion segments, number of cases with coronal plane deformity, bone mineral density (T value), UIV position, LIV position, operation time, intraoperative blood loss, osteotomy grading, and related imaging indicators were compared between the two groups. The hC 7-VSO of the vertebral body with significant differences between groups was taken, and the receiver operating characteristic curve (ROC) was used to evaluate its accuracy in predicting the occurrence of PJK. All 31 patients were followed up 13-52 months, with an average of 30.0 months. The patient's PJA was 1.4°-29.0° at last follow-up, with an average of 10.4°; PJK occurred in 8 cases (25.8%). There was no significant difference in gender, age, BMI, number of fusion segments, number of cases with coronal plane deformity, bone mineral density (T value), UIV position, LIV position, operation time, intraoperative blood loss, and osteotomy grading between the two groups ( P>0.05). Imaging measurements showed that the LL recovery value and T 8-L 3 vertebral hC 7-VSO in the PJK group were significantly higher than those in the non-PJK group ( P>0.05). There was no significant difference in hyperextension TK, hyperextension LL, hyperextension LKCA, TK recovery value, LL recovery value, kyphosis flexibility, hSVA, and T 2-T 7, L 4, L 5 vertebral hC 7-VSO ( P>0.05). T 8-L 3 vertebral hC 7-VSO was analyzed for ROC curve, and combined with the area under curve and the comprehensive evaluation of sensitivity and specificity, the best predictive index was hC 7-L 2, the cut-off value was 2.54 cm, the sensitivity was 100%, and the specificity was 60.9%. Preoperative back-forward Bending CT localization image can be used to predict the occurrence of PJK after posterior osteotomy and long-segment fusion fixation in adult spinal deformity. If the patient's T 8-L 2 vertebral hC 7-VSO is too large, it indicates a higher risk of postoperative PJK. The best predictive index is hC 7-L 2, and the cut-off value is 2.54 cm.

The association between bone mineral density and proximal junctional kyphosis in adult spinal deformity: a systematic review and meta-analysis.

Proximal junctional kyphosis (PJK) is a complication of surgical management for adult spinal deformity (ASD) with a multifactorial etiology. Many risk factors are controversial, and their relative importance is not fully understood. The authors aimed to elucidate the association between bone mineral density (BMD) and PJK. A systematic literature search was performed using PubMed and Web of Science keywords of "Proximal Junctional Kyphosis [MeSH] OR Proximal Junctional Failure [MeSH]" AND "Bone Mineral Density [MeSH] OR Hounsfield Units [MeSH] OR DEXA [MeSH]" set to the date range of January 2002 to July 2022. Studies required a minimum of 10 patients and 12 months of follow-up. Articles were included if they were in the English language and presented a primary retrospective cohort that included a comparison of patients with and without PJK, as well as a radiographic biomarker for BMD, such as Hounsfield units (HU) or T-score. A total of 18 unique studies with 2185 patients who underwent ASD surgery were identified. Of these, 537 patients (24.6%) developed PJK. Eight studies provided T-scores that were amenable to comparison, which found that patients who developed PJK were found to have lower BMD T-scores by a mean of -0.69 (95% CI -0.88 to -0.50; I2 = 63.9%, p < 0.001). The HU at the UIV among patients with the PJK group (n = 101) compared with the non-PJK group (n = 156) was found to be significantly lower (mean difference -32.35, 95% CI -46.05 to -18.65; I2 = 28.7%, p < 0.001). This meta-analysis suggests that low preoperative BMD as measured by T-score and a diagnosis of osteoporosis were associated with higher postoperative PJK. Additionally, lower HU on CT at the UIV were found to be significant risk factors for postoperative PJK as well. These findings suggest that more attention to preoperative BMD is a risk factor for PJK among ASD patients is warranted.

Paraspinal muscle degeneration and lower bone mineral density as predictors of proximal junctional kyphosis in elderly patients with degenerative spinal diseases: a propensity score matched case–control analysis

Study designRetrospective case–control study.ObjectivesProximal junctional kyphosis (PJK) is a postoperative complication involving the proximal segments which is commonly seen in patients with degenerative spine diseases (DSD). The purpose of the present study was to identify predictive factors for postoperative PJK in elderly patients with DSD.MethodsWe reviewed elderly patients with DSD who underwent thoracolumbar fusion involving no less than 3 levels. Patients who developed PJK were propensity score-matched with patients with DSD who received the same procedure but did not develop PJK. Demographic characteristics, sagittal vertical axis (SVA), computed tomography (CT) value (Hounsfield unit), and paraspinal muscle parameters were compared between PJK and non-PJK groups.ResultsEighty-three PJK and non-PJK patients were selected by propensity score matching for age, sex, history of smoking, body mass index, number of fused segments, and upper instrumented vertebra (UIV) location. SVA showed no significant difference between the two groups. In PJK group, fatty infiltration (FI) in erector spinae and multifidus was significantly greater, while the relative cross-sectional area (rCSA) of erector spinae was significantly smaller than that in non-PJK group. CT value was significantly lower in PJK group. Lower erector spinae rCSA and CT value of the UIV, higher erector spinae FI and multifidus FI were identified as predictors of postoperative PJK.ConclusionsPJK is a common complication in older patients with DSD. Paraspinal muscle degeneration and low bone mineral density of the UIV are predictors of PJK. Protective measures targeting paraspinal muscles and the UIV may help prevent postoperative PJK.

Risk Factors of Proximal Junctional Kyphosis in Adolescent Idiopathic Scoliosis-The Spinous Processes and Proximal Rod Contouring.

Proximal junctional kyphosis (PJK), as one of the most discussed problems after corrective surgery in adolescent idiopathic scoliosis (AIS), is still not fully clarified and seems to be multifactorial. Biomechanical and a few clinical studies have shown the influence of destruction of posterior ligaments by resection of spinous processes and some parameters concerning rod contouring as risk factors for PJK. To verify these results, 192 patients with AIS and corrective surgery via a posterior approach between 2009 and 2017 were included. Radiographic parameters were analyzed preoperatively (preOP), postoperatively (postOP), and with a mean follow up (FU) of 27 months. The participants were divided into two groups (PJK group and non-PJK group). The incidence of PJK was 15.6%. Contrary to the results of biomechanical studies, we could not find any significant influence of the spinous process resection. However, the PJK group had significantly larger preOP T4–T12 kyphosis (31.1° ± 13.93° vs. 23.3° ± 14.93°, p = 0.016). Furthermore, the PJK group showed a significantly larger rod contour angle (RCA) (8.0° ± 4.44° vs. 5.9° ± 3.28°, p = 0.003) and mismatch of postOP proximal junctional angle (PJA) and RCA (3.5° ± 5.72° vs. 0.9° ± 4.86°, p = 0.010) compared to the non-PJK group. An increase in the mismatch of postOP PJA and RCA (OR = 1.14, p = 0.008) and a high RCA are risk factors for PJK and need to be focused on by surgeons.

Proximal junctional kyphosis is a compensation for post-operative negative C2-FH in ASD patients: a cross-sectional study

BackgroundRecent studies have found that C2-FH is close to 0 cm in both standing and sitting position for asymptomatic adults. We hypothesize that the thoracic spine may compensate with PJK when the immediate post-operative C2-FH was not ideally restored in adult spinal deformity (ASD).MethodsThe inclusion criteria were as follows: ASD patients over 45 years old; Cobb angle > 30°; with posterior spinal correction surgery; at least 2 years follow-up. C2-FH was defined as the distance between the femoral heads to the C2 vertical line. All participants were divided into two groups according to the occurrence of PJK at the last follow-up: PJK group and non-PJK group.Results68 ASD patients, with a minimum follow-up of 2.5 years, were included. PJK was found in 24 patients (35.3%) while the rest 44 patients remained no sagittal malalignment. Immediately post-operative C2-FH showed significant difference between PJK group and non-PJK group (p = 0.015). However, at the last follow-up, C2-FH showed no significant difference between PJK and non-PJK group and the mean value of C2-FH in both groups was approximately − 1 cm, indicating that ASD patients could develop various compensatory mechanisms to maintain sagittal global balance. The AUC was 0.84 (95%CI 0.68–0.97), indicating the well effectiveness of ROC curve and cut-off value in predicting occurrence of PJK in ASD patients. Based on the ROC curve, the optimal cut-off value of C2-FH as indicators for occurrence of PJK was − 42.3 mm.ConclusionImmediate postoperative negative global malalignment (C2-FH < − 42.3 mm) may predict proximal junctional kyphosis in ASD patients. The normal value of C2-FH, − 1 cm, may be the target of global sagittal compensation, and PJK is a compensatory mechanism.Trial registration: 2021-LCYJ-DBZ-05, 2021.07, Retrospective study.

The Impact of Upper Instrumented Vertebra Orientation on Proximal Junctional Kyphosis: A Novel and Fixed Parameter, Fused Spinopelvic Angle.

A retrospective study. To evaluate the impact of upper instrumented vertebra (UIV) orientation including the fused spinopelvic angle (FSPA) on proximal junctional kyphosis (PJK). PJK is a challenging complication after adult spinal deformity (ASD) surgery. Some studies proposed UIV orientation act as a risk factor of PJK, but there remain debates because UIV orientation is changed by position. Therefore, we investigated the relationship between the FSPA, a novel parameter for the relationship between UIV and pelvis which did not change by position, and PJK. ASD patients who underwent long-segment fusion to the pelvis and followed up for more than two years were included. Comparative analysis was performed on spinopelvic parameters including UIV orientation parameters (UIV slope angle and FSPA) between PJK and non-PJK group. Binary regression analysis was conducted to find out the risk factors for PJK. And correlation analysis was conducted to find out the parameters that affect the FSPA. A total of 190 patients were included. PJK incidence was 13.2% (25/190). PJK group showed a significantly greater postoperative UIV slope (21.3° vs. 18.8°, P =0.041) and significantly lesser postoperative FSPA (-0.9° vs. 4.5°, P <0.001). In binary regression analysis, only FSPA acted as a risk factor of PJK (odds ratio=0.920, P =0.004). The FSPA has strong positive correlation with pelvic incidence (PI)-lumbar lordosis (LL) ( r =0.666, P <0.001) and negative correlation with lordosis distribution index (LDI) ( r =-0.228, P =0.004). The FSPA is a fixed parameter which is not dependent on position. A reduction of the FSPA increases the risk for PJK. The FSPA can be adjusted through PI-LL and LDI. Thus, surgeons should increase the FSPA by adjusting the PI-LL and LDI during ASD surgery to prevent PJK.

A predictive scoring system for proximal junctional kyphosis after posterior internal fixation in elderly patients with chronic osteoporotic vertebral fracture: A single-center diagnostic study

ObjectiveTo establish a predictive scoring system for proximal junctional kyphosis (PJK) after posterior internal fixation in elderly patients with chronic osteoporotic vertebral fracture (COVF).Materials and methodsThe medical records of 88 patients who were diagnosed with COVF and underwent posterior internal fixation in our hospital from January 2013 to December 2017 were retrospectively analyzed. The included patients were divided into two groups according to whether they suffered PJK after surgery, namely, the PJK group (25 cases) and non-PJK group (63 cases). The following clinical characteristics were recorded and analyzed: age, gender, body mass index (BMI), bone mineral density (BMD), smoking history, fracture segment, proximal junction angle, sagittal vertebral axis, pelvic incidence (PI)–lumbar lordosis (LL), pelvic tilt (PT), sacral slope (SS), posterior ligamentous complex (PLC) injury, upper instrumented vertebra, lower instrumented vertebra, and the number of fixed segments. The prevalence of these clinical characteristics in the PJK group was evaluated, and the scoring system was established using logistic regression analysis. The performance of the scoring system was also prospectively validated.ResultsThe predictive scoring system was established based on five clinical characteristics confirmed as significant predictors of PJK, namely, age > 70 years, BMI > 28 kg/m2, BMD < −3.5 SD, preoperative PI-LL > 20°, and PLC injury. PJK showed a significantly higher score than non-PJK (7.80 points vs. 2.83 points, t=9.556, P<0.001), and the optimal cutoff value for the scoring system was 5 points. The sensitivity and specificity of the scoring system for predicting postoperative PJK were 80.00% and 88.89%, respectively, in the derivation set and 75.00% and 80.00% in the validation set.ConclusionThe predictive scoring system was confirmed with satisfactory sensitivity and specificity in predicting PJK after posterior internal fixation in elderly COVF patients. The risk of postoperative PJK in patients with a score of 6–11 is high, while the score of 0–5 is low.

Unmatched rod contouring at the proximal end predisposes to occurrence of junctional kyphosis in early-onset scoliosis patients undergoing traditional growing rods treatment

Study designA retrospective case series.ObjectiveTo investigate whether unmatched rod contouring at the proximal end predisposed to the occurrence of proximal junctional kyphosis (PJK) in early-onset scoliosis (EOS) patients after traditional growing rods (TGR) treatment.Summary of background dataTGR treatment has become a mainstay of treatment for EOS patients. PJK is one of the most common alignment-related complications.MethodsA consecutive series of EOS patients who had undergone TGR treatment were retrospectively reviewed. They were divided into PJK and non-PJK groups according to the occurrence of PJK or not. Demographic data, surgical strategies, and radiographic parameters were recorded and compared between groups. Proximal junctional angle (PJA) was defined as the angle between the caudal endplate of the UIV and the cephalad endplate of the second supradjacent vertebra above the UIV, while proximal rod contouring angle (PRCA) was defined as the angle of proximal rod contouring, which was represented by the angle between the cephalad endplate of the UIV and the caudal endplate of the second vertebra caudal to the UIV. Unmatched proximal rod contouring was regarded if the postoperative PRCA-PJA difference was greater than 5°.ResultsThis study finally included 73 patients. The mean age at the index surgery was 6.5 ± 2.2 years (range, 2–10 years). Mean follow-up lasted 5.0 ± 1.7 years (range, 2–9 years). They received mean 4.6 ± 1.6 lengthening procedures. There were 13 patients who were observed with PJK (18%). In comparison with the non-PJK group, the PJK group showed a larger preoperative major curve (82 ± 21° vs 70 ± 17°, P = 0.041) and global kyphosis (57 ± 6° vs. 44 ± 15°, P = 0.044). In addition, the PJK group had significantly larger postoperative PJA (10 ± 3 vs. 5 ± 3, P<0.001) and greater postoperative PJA-PRCA (6 ± 3 vs. 3 ± 3, P = 0.031). The proportion of patients with unmatched proximal rod contouring in PJK group was significantly higher than that in the non-PJK group (69% vs. 25%). Multiple logistic regression showed that preoperative GK>50°, postoperative PJA>10 and postoperative unmatched proximal rod contouring were the risk factors in predicting PJK after TGR treatment.ConclusionApproximately 18% EOS patients experienced PJK after TGR treatment. Unmatched proximal rod contouring may be an independent risk factor of PJK occurrence, in addition to greater preoperative GK and larger postoperative PJA.Level of evidence3.

Relook into the Risk Factors of Proximal Junctional Kyphosis in Early Onset Scoliosis Patients: Does the Location of Upper Instrumented Vertebra in Relation to the Sagittal Apex Matter?

ObjectiveGrowing rods surgery is the mainstay of treatment for early‐onset scoliosis (EOS) while proximal junctional kyphosis (PJK) is one of the most commonly reported postoperative complications. We sought to investigate the impact of the location of upper instrumented vertebra (UIV) in relation to the sagittal apex on proximal junctional kyphosis in EOS after traditional growing rods (GRs) treatment.MethodsA total of 102 EOS patients who received traditional growing rods treatment with a follow‐up of at least 2 years between 2009 and 2020 were retrospectively reviewed. Radiographic measurements were performed before and after the index surgery and at the latest follow‐up. We investigated the coronal Cobb angle and spinopelvic parameters of the whole spine. The location of the UIV, apex, lower instrumented vertebra (LIV), inflection vertebra (IV), the number and distance of UIV‐apex, LIV‐apex and IV‐apex were also recorded. Risk factors for PJK were analyzed by logistic regression analysis.ResultsPJK was observed in 21 patients (20.6%) during the follow‐up period. The PJK group showed a younger age at the index surgery (5.9 vs. 7.1 years, P = 0.042), more lengthening procedure times (5.0 vs. 4.0, P = 0.032), larger preoperative coronal Cobb angle (82.0 vs. 75.6°, P = 0.038), higher correction rate (51.2% vs. 44.4%, P = 0.047) and larger postoperative proximal junctional angle (PJA) (13.9 vs. 5.5°, P < 0.001) than the non‐PJK group. The ratio of the number and distance from UIV‐apex to IV‐apex also differed significantly between the two groups. The logistic regression revealed that age at the index surgery ≤ 7 years, the ratio of the number from UIV‐ apex to IV‐ apex ≤ 0.6 and the ratio of the distance from UIV‐ apex to IV‐ apex ≤ 0.6 were independent risk factors for postoperative PJK.ConclusionBesides younger age, a closer location of UIV relative to the sagittal apex is identified to be an independent risk factor of postoperative PJK. Selection of UIV at a relatively farther location away from the sagittal apex might help prevent occurrence of PJK.

The standing T1-L1 pelvic angle: a useful radiographic predictor of proximal junctional kyphosis in adult spinal deformity.

Proximal junctional kyphosis (PJK), which can worsen a patient's quality of life, is a common complication following the surgical treatment of adult spinal deformity (ASD). Although various radiographic parameters have been proposed to predict the occurrence of PJK, the optimal method has not been established. The present study aimed to investigate the usefulness of the T1-L1 pelvic angle in the standing position (standing TLPA) for predicting the occurrence of PJK. The authors retrospectively extracted data for patients with ASD who underwent minimum 5-level fusion to the pelvis with upper instrumented vertebra between T8 and L1. In the present study, PJK was defined as ≥ 10° progression of the proximal junctional angle or reoperation due to progressive kyphosis during 1 year of follow-up. The following parameters were analyzed on whole-spine standing radiographs: the T1-pelvic angle, conventional thoracic kyphosis (TK; T4-12), whole-thoracic TK (T1-12), and the standing TLPA (defined as the angle formed by lines extending from the center of T1 and L1 to the femoral head axis). A logistic regression analysis and a receiver operating characteristic curve analysis were performed. A total of 50 patients with ASD were enrolled (84% female; mean age 74.4 years). PJK occurred in 19 (38%) patients. Preoperatively, the PJK group showed significantly greater T1-pelvic angle (49.2° vs 34.4°), conventional TK (26.6° vs 17.6°), and standing-TLPA (30.0° vs 14.9°) values in comparison to the non-PJK group. There was no significant difference in the whole-thoracic TK between the two groups. A multivariate analysis showed that the standing TLPA and whole-thoracic TK were independent predictors of PJK. The standing TLPA had better accuracy than whole-thoracic TK (AUC 0.86 vs 0.64, p = 0.03). The optimal cutoff value of the standing TLPA was 23.0° (sensitivity 0.79, specificity 0.74). Using this cutoff value, the standing TLPA was the best predictor of PJK (OR 8.4, 95% CI 1.8-39, p = 0.007). The preoperative standing TLPA was more closely associated with the occurrence of PJK than other radiographic parameters. These results suggest that this easily measured parameter is useful for the prediction of PJK.

Risk Factors for Proximal Junctional Kyphosis in Fusions from the Sacrum to L1 or L2 for Adult Spinal Deformity.

Introduction Several targets have been proposed to achieve satisfactory alignment and favorable outcomes in adult spinal deformity surgery. Stopping the upper instrumented vertebra (UIV) at the thoracolumbar junction levels, especially between T11 and L1, is considered a high-risk factor for the development of proximal junctional kyphosis (PJK). Nevertheless, it is unknown in which patients the results of surgery are satisfactory when L1 or L2 is set as UIV with lumbosacral fixation. This study aimed to identify the risk factors for PJK in patients with lumbosacral fixation with L1 or L2 as UIV. Methods From January 2011 to December 2019, 21 consecutive patients who underwent lumbopelvic fixation for adult spinal deformity were included. The patients were divided into two groups: the PJK group (n=7) and the nonPJK group (n=14). Patients who experienced PJK within half a year of surgery were included in the PJK group. Pelvic incidence (PI), lumbar lordosis (LL), pelvic tilt (PT), thoracic kyphosis (TK), thoracic compensation (TK compensation), sagittal vertical axis (SVA), T10-L2 angle, and T1 pelvic angle (TPA) were measured before and after surgery. Results No difference was found between the two groups in terms of age and sex at the time of surgery. The indices that were significantly different between the two groups were preoperative PT, PI minus LL, TK, TPA, TK compensation, and postoperative T10-L2 angle. No significant differences were found in postoperative LL, PI minus LL, PT, TK, TPA, or SVA. Conclusions Preoperative X-ray indices, including preoperative TPA, TK compensation, TK, PT, and PI-LL, determined the risk of PJK in fusions from the sacrum to L1 or L2. Appropriate patient selection is crucial for the success of this surgery.

Incidence and Radiological Risk Factors of Proximal Junctional Kyphosis in Adolescent Idiopathic Scoliosis Following Pedicle Screw Instrumentation with Rod Derotation and Direct Vertebral Rotation: A Minimum 5-Year Follow-Up Study.

Several studies have reported incidence and risk factors for the development of proximal junctional kyphosis (PJK) in patients with adolescent idiopathic scoliosis (AIS). However, there is little information regarding long-term follow-up after pedicle screw instrumentation (PSI) with rod derotation (RD) and direct vertebral rotation (DVR). Sixty-nine AIS patients who underwent deformity correction using PSI with RD and DVR were retrospectively analyzed in two groups according to the occurrence of PJK, with a minimum five-year follow-up, including a non-PJK group (n = 62) and PJK group (n = 7). Radiological parameters were evaluated at preoperative, postoperative, and last follow-up. Incidence for PJK was 10.1% (7/69 patients), with a mean 9.4-year follow-up period. The thoracolumbar/lumbar curve (TL/L curve) was proportionally higher in the PJK group. The proximal compensatory curve was significantly lower in the PJK group than in the non-PJK group preoperatively (p = 0.027), postoperatively (p = 0.001), and at last follow-up (p = 0.041). The development of PJK was associated with the TL/L curve pattern, lower preoperative proximal compensatory curve, and over-correction of the proximal curve for PSI with RD and DVR. Therefore, careful evaluation of compensatory curves as well as of the main curve is important to prevent the development of PJK in the treatment of AIS.

Effect of overcorrection on proximal junctional kyphosis in adult spinal deformity: analysis by age-adjusted ideal sagittal alignment

BACKGROUND CONTEXTThe effect of the degree of lumbar lordosis (LL) correction on proximal junctional kyphosis (PJK) has not been analyzed in context of the age-adjusted sagittal alignment goal. PURPOSETo determine the effect of sagittal correction on the incidence of PJK after an age-adjusted analysis in patients with adult spinal deformity (ASD). STUDY DESIGN/SETTINGRetrospective comparative study. PATIENT SAMPLESeventy-eight ASD patients who underwent deformity correction. OUTCOME MEASURESVisual analog scale (VAS), Oswestry Disability Index (ODI), and imaging. METHODSThis study included 78 ASD patients who underwent deformity correction and were followed-up more than 2 years. Patients were grouped according to the degree of LL correction relative to pelvic incidence (PI) by adjusting for age using the following formula: (age-adjusted ideal PI - LL) - (postoperative PI - LL). These were group U (undercorrection; <−10˚, N=15), group I (ideal correction; −10˚–10˚, N=34), and group O (over correction, >10˚, N=29). Various clinical and radiological parameters were compared among groups. The risk factors for PJK were also evaluated. RESULTSThe overall incidence of PJK was 32.1% (25/78), with significantly higher PJK rate in group O (48.3%) compared with groups U (13.3%) and I (26.5%) (p=.041). The degree of postoperative LL correction relative to the PI by adjusting for age was a risk factor for the development of PJK (11.4° for PJK vs. 0.2° for non-PJK, p=.033). In addition, 2-year postoperative VAS (7.0 vs. 3.4, p<.001) and ODI (28.9 vs. 24.8, p=.040) scores were significantly higher in the PJK group than in the non-PJK group. A small PI (PI < 45°) was associated with a tendency of overcorrection (73.3%, P < 0.001) and thereby with the high incidence of PJK (53.3%, p=.005). CONCLUSIONSOvercorrection of LL relative to PI considering age-adjusted ideal sagittal alignment tends to increase the incidence of PJK. The incidence of PJK is expected to be high in patients with low PI (<45°) because of the tendency of overcorrection. To reduce the risk of PJK, surgeons should take age-adjusted parameters into account and exercise caution not to overcorrect patients with low PI, since this can result in suboptimal clinical outcomes.

190. C2 pelvic angle (C2PA) is a useful radiographic parameter that correlates with clinical outcomes of symptomatic proximal junctional kyphosis

<h3>BACKGROUND CONTEXT</h3> Proximal junctional kyphosis (PJK) after spine deformity surgery is a radiographic phenomenon defined based on the proximal junctional angle (PJA). Currently, there is minimal literature demonstrating correlation between clinical outcome scores and PJA. The lack of correlation may be due to the inadequate assessment of global spinal alignment from the PJA. The C2PA is a novel radiographic angle that portrays the mismatch between the global spinal alignment and alignment proximal to the spine that corresponds with ODI and SRS scores. <h3>PURPOSE</h3> The definition of PJK after spine deformity surgery is based on the PJA. Despite the growing amount of literature on PJK, minimal correlation exists between PJK and clinical outcome scores. PJA poorly represents, and is difficult to measure, PJK for global spinal alignment after deformity surgery. C2PA is a novel radiographic angle that demonstrates the difference between global spinal alignment and alignment proximal to the spinal construct. <h3>STUDY DESIGN/SETTING</h3> Prospectively collected cohort. <h3>PATIENT SAMPLE</h3> A radiographic review was performed on 98 deformity patients from July 2015-July 2018. <h3>OUTCOME MEASURES</h3> Logistic regression and Chi-square analyses were performed to study the relationship between the postop PJA and C2PA with ODI/SRS scores. <h3>METHODS</h3> A radiographic review was performed on 98 deformity patients from July 2015-July 2018. The angle between the posterior superior sacrum, C2 centroid and upper instrumented vertebrae (UIV) centroid in the pre- and postop setting (2-year or prior to return to OR) were measured and labeled as C2PA. The patients were divided into PJK and non-PJK groups based on (a) PJK defined as PJA >20° and (b) PJK defined as C2PA >20°. Logistic regression and Chi-square analyses were performed to study the relationship between the postop PJA and C2PA with ODI/SRS scores. <h3>RESULTS</h3> Of the 98 patients, there were 20 patients with PJK when it was defined as PJA >20°. There was no statistically significant correlation between ODI and SRS scores in the non-PJK and PJK group when it was defined as PJA. There were minimal differences between the ODI scores (8.0 vs 7.0, p=0.66) and the SRS total scores (71.3 vs 70.6, p=0.85) in the Non-PJK and PJK group when it was defined as PJA >20°. When PJK was defined as C2PA >20°, there were 31 patients with PJK. There were statistically significant differences between the non-PJK and PJK group for both ODI (8.0 vs 16.0, p=0.015) and SRS total scores (97.0 vs 88.0, p=0.010) when PJK was defined as C2PA >20° <h3>CONCLUSIONS</h3> This is the first study demonstrating that C2PA is a superior radiographic representation of PJK, and directly correlates with patient-reported outcomes. C2PA >20° is the critical angle that corresponds with clinical PJK. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.