Proximal Junctional Kyphosis Patients Research Articles

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.

The Shape of the Fused Spine is Associated With Acute Proximal Junctional Kyphosis in Adult Spinal Deformity: An Assessment Based on Vertebral Pelvic Angles.

Retrospective review of prospective database. Vertebral pelvic angles (VPAs) account for complexity in spine shape by assessing the relative position of each vertebra with regard to the pelvis. This study uses VPAs to investigate the shape of the fused spine after T10-pelvis fusion, in patients with adult spinal deformity (ASD), and then explores its association with proximal junctional kyphosis (PJK). Included patients had radiographic evidence of ASD and underwent T10-pelvis realignment. VPAs were used to construct a virtual shape of the post-operative spine. VPA-predicted and actual shapes were then compared between patients with and without PJK. Logistic regression was used to identify components of the VPA-based model that were independent predictors of PJK occurrence and post-operative shape. 287 patients were included. VPA-predicted shape was representative of the true post-operative contour, with a mean point-to-point error of 1.6-2.9% of the T10-S1 spine length. At 6-weeks follow-up, 102 patients (35.5%) developed PJK. Comparison of the true post-operative shapes demonstrated that PJK patients had more posteriorly translated vertebrae from L3 to T7 (P < .001). Logistic regression demonstrated that L3PA (P = .047) and T11PA (P < .001) were the best independent predictors of PJK and were, in conjunction with pelvic incidence, sufficient to reproduce the actual spinal contour (error <3%). VPAs are reliable in reproducing the true, post-operative spine shape in patients undergoing T10-pelvis fusion for ASD. Because VPAs are independent of patient position, L3PA, T11PA, and PI measurements can be used for both pre- and intra-operative planning to ensure optimal alignment.

P95. A comparative analysis of thoracic decompensation versus proximal junctional kyphosis in response to adult spinal deformity corrective surgery

<h3>BACKGROUND CONTEXT</h3> Thoracic decompensation (TD) represents a distinct radiographic complexity from proximal junctional kyphosis (PJK). Few studies exist on the occurrence of TD following adult spinal deformity (ASD) corrective surgery. <h3>PURPOSE</h3> To assess the incidence of TD following ASD-corrective surgery in comparison with the occurrence of PJK. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort. <h3>PATIENT SAMPLE</h3> A total of 689 ASD patients. <h3>OUTCOME MEASURES</h3> ASD, TD, PJK, thoracic compensation. <h3>METHODS</h3> ASD patients with complete baseline (BL) and two-year (2Y) followup were included. Patients were divided into groups: those who developed TD: T4-T12 >54.2° and those who developed PJK. Further analysis assessed outcomes among patients with both TD and PJK (TDPJK). Thoracic compensation was defined as expected thoracic kyphosis minus BL thoracic kyphosis. Means comparison tests and multivariable logistic regression analysis assessed differences between patient groups. <h3>RESULTS</h3> A total of 373 patients met inclusion criteria. Patient breakdown by radiographic outcome was: TD (N=31), PJK (N=223) and TDPJK (N=119). Age, gender, and ASD-mFI were similar between TD and PJK patients. TD patients were more likely to be osteoporotic than PJK patients, p < 0.05. Procedures on TD patients were less invasive and utilized a shorter construct (9.3 vs 11.5 levels; both p < 0.05). TD patients had significantly greater cervical lordosis, thoracic kyphosis, and lumbar lordosis than PJK patients at BL and 2Y follow-up, all p < 0.05. Thoracic compensation was significantly associated with TD (OR 1.07 [CI 1.04-1.09], p < 0.001) controlling for age, ASD-mFI, and invasiveness. TDPJK had the highest complication rate (84.9%), significantly greater than PJK patients (70.9%), and TD patients (61.3%), both p < 0.05. PJK patients were 78.7% less likely to develop PJF than TDPJK patients (OR 0.213 [CI 0.101-0.453], p < 0.001). <h3>CONCLUSIONS</h3> Patients who developed thoracic decompensation were more likely to present with osteoporosis, but had less invasive procedures and levels fused than patients with proximal junctional kyphosis. The tradeoff between fusing too much resulting in proximal junctional kyphosis and fusing too little predisposing to thoracic decompensation can serve as the basis of future studies to determine optimal construct length to balance these two risks. Thoracic compensation was predictive of postoperative thoracic decompensation in adult spinal deformity-correction. Patients who developed TDPJK had the highest rate of complications and greater odds of junctional failure. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Risk factors for proximal junctional kyphosis after pediatric spinal deformity surgery with halo gravity traction.

To determine risk factors for proximal junctional kyphosis (PJK) in pediatric patients with scoliosis undergoing halo gravity traction (HGT) prior to posterior spinal fusion (PSF). Data from consecutive patients who underwent PSF after HGT with 2-year follow-up were retrospectively collected from a single center. Patients were divided into two groups: PJK vs. no PJK. Twenty-five patients (age 13.6 ± 3.1years) underwent HGT for a mean of 42 ± 37days. Eight patients (32%) developed radiographic PJK and 1 (4%) developed proximal junctional failure. PJK patients had greater loss of cervical lordosis (-17.4 ± 23.2 vs. 2.7 ± 16.2°, p < 0.05), greater increase in lumbar lordosis (9.3 ± 19.5 vs. -2.8 ± 12.8°; p = 0.034) during traction, and smaller overall major coronal curve angle correction (-16.8 ± 30.6 vs. -36.6 ± 16.4°; p = 0.026). From postoperative to last follow-up, PJK patients had a greater increase in upper end vertebrae (UEV) slope (3.3 ± 7.8 vs. -4.0 ± 7.7°; p = 0.004). Selection of UIV based on which vertebra was most level either pre-traction or in-traction was not associated with PJK development (p > 0.05). In-traction radiographic changes of decreased cervical lordosis, decreased major coronal curve, increased lumbar lordosis, and disruption of cervical sagittal balance at last follow-up may have implications for level selection and risk of PJK.

P102. Determining the impact of proximal junctional kyphosis on cost utility in adult spinal deformity patients

<h3>BACKGROUND CONTEXT</h3> With health care costs on the rise, hospitals have increasingly focused on providing economically efficient medical services. Adult spinal deformity surgery remains an expensive medical intervention with high risk for complications and revisions, especially following mechanical failure in the context of proximal junctional kyphosis (PJK). We sought to evaluate the impact of PJK on associated expenditures following an index surgery for ASD. <h3>PURPOSE</h3> To evaluate the effect of proximal junctional kyphosis on the cost effectiveness of corrective adult deformity surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study of a prospective single-center database of ASD patients. <h3>PATIENT SAMPLE</h3> A total of 147 Adult Spinal Deformity Patients. <h3>OUTCOME MEASURES</h3> Complications, HRQLs (Oswentry Disability Index [ODI]), Quality adjusted life years (QALY). <h3>METHODS</h3> Adult Spinal deformity patients with 2-year HRQL follow-up were included. Utility data was calculated using published conversion methods to convert ODI to SF-6D. QALYs utilized a 3% discount rate to account for residual decline to life expectancy (78.7 years). Costs were calculated using the PearlDiver database incorporating complications and comorbidities classified according to CMS standard definitions. Reimbursement consisted of a standardized estimate using regression analysis of Medicare pay-scales for all services rendered within a 30-day window, including estimates regarding costs of postoperative complications, outpatient health care encounters, reoperations and revisions. After accounting for all postoperative events, including mortality, cost per QALY by 2Y was calculated for revisions that occurred due to proximal junctional kyphosis. <h3>RESULTS</h3> A total of 147 adult spinal deformity patients met inclusion criteria (55.22years, 54% Female). At baseline, patients presented radiographically as: Pelvic Tilt (23.66±11.7), Pelvic Incidence- Lumbar Lordosis (-2.9±12.6), Sagittal Vertical Axis (60.5±76.8), T1 Pelvic Angle (22.6±14.3). Surgical details: EBL of 1823 mL, operative time of 327 min, with .4% undergoing an anterior approach, 90.2% posterior-only approach, and 9.3% combined approach. Overall, 54.3% of patients developed PJK within 2 years postoperatively, with 22% undergoing reoperation for PJK. Average cost of revision surgery due to PJK was $93,688 ± $21,467. The cost for PJK patients, including the cost associated with their revision surgery, was higher ($103,760 vs $71,000). Baseline ODI (39 vs 32) and 2Y ODI (39 vs 27) were higher for PJK patients, however, PJK patients did improve to a greater degree (-12 vs -10). The overall cost per QALY by 2Y was higher for PJK patients ($116,170 vs $95,347). <h3>CONCLUSIONS</h3> Patients that developed PJK had an almost $30,000 higher initial cost at 2 years. When looking at the cost per quality adjusted life years by 2Y, PJK resulted in slightly more than $20,000 in cost. These findings suggest prophylactic measures to mitigate PJK may improve the cost utility of adult spinal deformity surgery and can help policy efforts for adequate resource allocation for these complex patients. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

141. Preoperative paraspinal fat atrophy of the upper instrumented vertebrae musculature in spine deformity surgery is a risk factor for proximal junctional kyphosis and sagittal malalignment

141. Preoperative paraspinal fat atrophy of the upper instrumented vertebrae musculature in spine deformity surgery is a risk factor for proximal junctional kyphosis and sagittal malalignment

P95. Lower Hounsfield units (HU) of the upper instrumented vertebrae (UIV) may contribute to proximal junctional kyphosis (PJK) in adult spinal deformity (ASD) surgery

BACKGROUND CONTEXT HU on computed tomography (CT) has been associated with bone mineral density (BMD). We wished to correlate PJK after ASD surgery and HU as measured by CT. PURPOSE To evaluate if HU at the UIV, UIV+1 and UIV+2 was correlated with PJK. STUDY DESIGN/SETTING A retrospective study. PATIENT SAMPLE Single center with ASD patients undergoing >6 levels of fusions from the lower thoracic spine to the sacrum with minimum 2-year follow-up. OUTCOME MEASURES Radiographic spinopelvic parameters were measured, including pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), PI-LL, sacral slope (SS), T1 pelvic angle (TPA), T5-T12 thoracic kyphosis (TK), sagittal vertical axis (SVA), and PJK rates. PJK was defined as 10° kyphosis between UIV and UIV+2 or as 10° more kyphosis at UIV and UIV+2 than preop. METHODS A retrospective study ASD patients ≥6 fusion levels from the LT spine to S1 with minimum of 2-year follow-up was performed. Demographic and spinopelvic parameters (PI-LL, SVA, TPA, PT) were measured. HU values were measured on preop CT at UIV, UIV+1, and UIV+2 four separate times at the: mid-sagittal plane, mid-body axial, axial near the superior and inferior endplates. RESULTS Fifty-four patients (mean age, 64.95 years; 20 males) met inclusion criteria, with 30 patients with PJK and 24 patients without, and mean follow-up was 2.79 years. There was no difference in age, BMI, sex, and follow-up in the two groups. There was no statistical difference between groups with regard to PI, SS, PT, LL, PI-LL, TK, TPA and SVA (p > 0.05). Mean preoperative HUs at UIV, UIV+1 and UIV+2 were 119.83, 123.53 and 129.03 in PJK patients, and 154.88, 158.50 and 161.58 in patients without PJK (p = 0.006, 0.009, 0.012). Postop PT and TPA were higher in PJK patients than in those without (p =0.003 and0.017). However, there was no statistical difference between groups with regard to PI, SS, LL, PI-LL, TK and SVA postoperatively (p > 0.05). A receiver operating characteristic (ROC) curve for preoperative HU at UIV as a predictor for PJK was established, with an AUC of 0.726 (95% CI: 0.592-0.86). The optimal HU cut-off value determined by the Youden index is 104.5HU (sensitivity, 0.875; specificity, 0.533). CONCLUSIONS PJK is a multifactorial issue, and lower HU values at the UIV, UIV+1 and UIV+2 in patients undergoing LT to the sacrum fusions for ASD may contribute to PJK. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

169. To prevent PJK in Scheuermann's Kyphosis restore kyphosis to patient's PI value and choose proximal UIV

BACKGROUND CONTEXT Surgical correction of Scheuermann's kyphosis is challenging with high rates of proximal junctional kyphosis (PJK). Historically an anterior release and posterior fusion was thought to optimize correction. However, pedicle screws treatment through an all-posterior approach is the norm. No comparison study exists on PJK risks between anterior/posterior fusion and posterior fusion utilizing pedicle screws or posterior hybrid fixation in the treatment of SK. PURPOSE To determine if choosing a more proximal UIV and matching the kyphosis to pelvic incidence will lower the presence of PJK in SK patients. STUDY DESIGN/SETTING Retrospective, multi institution. PATIENT SAMPLE A total of 84 operative Scheurmann's kyphosis patients. OUTCOME MEASURES Kyphosis, PJK, kyphosis correction, pelvic incidence, kyphosis minus pelvic incidence METHODS SK patients operated with pedicle screw (PS), hybrid fixation (HF), and anterior/posterior fusions with hybrid fixation (AP). Sagittal parameters, % correction, UIV, kyphosis minus PI, Lordosis minus PI, PI-LL at early postop and minimum 2-year FU were measured. T1/T2 UIV were grouped together and compared to T3 and distal. RESULTS Median preop kyphosis was significantly higher in AP (p<0.001). Median postop kyphosis was significantly higher in PS (p=0.048). Percent correction was highest in AP (p<0.001). A total of 22.6% patients had PJK at early postop, which increased to 52.3% at final follow-up. PS were significantly more likely to have PJK at early postop (p=0.05), however at final follow up, all groups were similar (p=0.27). UIV at T1/T2 and postop kyphosis within 10° of pelvic incidence (Kyphosis - PI> -10° at postop). When correcting kyphosis-PI to > -10° and UIV was chosen to be T1/T2, PJK developed in 30% of patients. When fusing to T1/T2 and kyphosis-PI < -10°, 63% of patients developed PJK. When kyphosis-PI > -10° but UIV chosen at T3 or below, 66% of patients developed PJK. When fusing to T3 or below and failing to correct kyphosis-PI > -10°, 90% of patients developed PJK. CONCLUSIONS Incidence of PJK is higher in SK compared to that reported in AIS and similar irrespective of instrumentation or approach. Use of hooks provides benefits in the early postop but not at later follow up. Fusing short and overcorrection of kyphosis contributes towards PJK. Target kyphosis should be PI >-10° and UIV at T1/2. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. Surgical correction of Scheuermann's kyphosis is challenging with high rates of proximal junctional kyphosis (PJK). Historically an anterior release and posterior fusion was thought to optimize correction. However, pedicle screws treatment through an all-posterior approach is the norm. No comparison study exists on PJK risks between anterior/posterior fusion and posterior fusion utilizing pedicle screws or posterior hybrid fixation in the treatment of SK. To determine if choosing a more proximal UIV and matching the kyphosis to pelvic incidence will lower the presence of PJK in SK patients. Retrospective, multi institution. A total of 84 operative Scheurmann's kyphosis patients. Kyphosis, PJK, kyphosis correction, pelvic incidence, kyphosis minus pelvic incidence SK patients operated with pedicle screw (PS), hybrid fixation (HF), and anterior/posterior fusions with hybrid fixation (AP). Sagittal parameters, % correction, UIV, kyphosis minus PI, Lordosis minus PI, PI-LL at early postop and minimum 2-year FU were measured. T1/T2 UIV were grouped together and compared to T3 and distal. Median preop kyphosis was significantly higher in AP (p<0.001). Median postop kyphosis was significantly higher in PS (p=0.048). Percent correction was highest in AP (p<0.001). A total of 22.6% patients had PJK at early postop, which increased to 52.3% at final follow-up. PS were significantly more likely to have PJK at early postop (p=0.05), however at final follow up, all groups were similar (p=0.27). UIV at T1/T2 and postop kyphosis within 10° of pelvic incidence (Kyphosis - PI> -10° at postop). When correcting kyphosis-PI to > -10° and UIV was chosen to be T1/T2, PJK developed in 30% of patients. When fusing to T1/T2 and kyphosis-PI < -10°, 63% of patients developed PJK. When kyphosis-PI > -10° but UIV chosen at T3 or below, 66% of patients developed PJK. When fusing to T3 or below and failing to correct kyphosis-PI > -10°, 90% of patients developed PJK. Incidence of PJK is higher in SK compared to that reported in AIS and similar irrespective of instrumentation or approach. Use of hooks provides benefits in the early postop but not at later follow up. Fusing short and overcorrection of kyphosis contributes towards PJK. Target kyphosis should be PI >-10° and UIV at T1/2.

Incidence of Proximal Junctional Kyphosis With Pedicle Screws at Upper Instrumented Vertebrae in Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis.

Study Design:Longitudinal cohort.Objectives:Posterior spinal fusion (PSF) using all-pedicle screw constructs has become the standard procedure in the treatment of adolescent idiopathic scoliosis (AIS). However, there have been several reports that all-pedicle screw constructs or the use of pedicle screws at the upper instrumented vertebrae (UIV) increases the incidence of proximal junctional kyphosis (PJK). We aimed to evaluate the impact of instrumentation type on the incidence of PJK following PSF for AIS.Methods:We performed a stratified random sampling from 3654 patients enrolled in a multicenter database of surgically treated AIS to obtain a representative sample from all Lenke types. Patients were then allocated into 3 groups based on the instrumentation type: all-pedicle screw (PS), hook at UIV with pedicle screws distally (HT), and hybrid constructs (HB). We measured proximal junctional angle (PJA) and defined PJK as PJA ≥ 10° and PJA progression of >10° at the final follow-up.Results:Fifteen (4.3%) of 345 cases had PJK. PJK was significantly more common in PS (11%) compared with HB (1%) and HT (0%) (P < .001). PJK patients were similar to non-PJK patients regarding age, sex, curve type, UIV, and preoperative coronal Cobb angle. Thoracic kyphosis was significantly higher in the PJK group before surgery. Patients who developed PJK had a statistically significantly larger negative sagittal balance compared with the non-PJK group.Conclusion:The incidence of PJK was 4.3% and was more common in all-pedicle screw constructs. Using hooks at UIV might be a treatment strategy to limit PJK.

Cervical, Thoracic, and Spinopelvic Compensation After Proximal Junctional Kyphosis (PJK): Does Location of PJK Matter?

Study Design:Retrospective case series.Objective:Compensatory changes above a proximal junctional kyphosis (PJK) have not been defined. Understanding these mechanisms may help determine optimal level selection when performing revision for PJK. This study investigates how varying PJK location changes proximal spinal alignment.Methods:Patients were grouped by upper instrumented vertebrae (UIV): lower thoracic (LT; T8-L1) or upper thoracic (UT; T1-7). Alignment parameters were compared. Correlation analysis was performed between PJK magnitude and global/cervical alignment.Results:A total of 369 patients were included; mean age of 63 years, body mass index 28, and 81% female, LT (n = 193) versus UT (n = 176). The rate of radiographic PJK was 49%, higher in the LT group (55% vs 42%, P = .01). The UT group displayed significant differences in all cervical radiographic parameters (P < .05) between PJK versus non-PJK patients, while the LT group displayed significant differences in T1S and C2-T3 sagittal vertical axis (SVA) (CTS). In comparing UT versus LT patients, UT had more posterior global alignment (smaller TPA [T1 pelvic angle], SVA, and larger PT [pelvic tilt]) and larger anterior cervical alignment (greater cSVA [cervical SVA], T1S-CL [T1 slope–cervical lordosis] mismatch, CTS) compared to LT. Correlation analysis of PJK magnitude and location demonstrated a correlation with increases in CL, T1S, and CTS in the UT group. In the LT group, PT increased with PJK angle (r = 0.17) and no significant correlations were noted to SVA, cSVA, or T1S-CL.Conclusions:PJK location influences compensation mechanisms of the cervical and thoracic spine. LT PJK results in increased PT and CL with decreased CTS. UT PJK increases CL to counter increases in T1S with continued T1S-CL mismatch and elevated cSVA.

225. Global alignment and proportion score does not predict proximal junctional kyphosis

BACKGROUND CONTEXT Proximal junctional kyphosis (PJK) is a devastating complication of adult spinal deformity (ASD) surgery. Optimal alignment specifications to maximize quality of life while limiting PJK have yet to be defined. Previous studies have primarily examined sagittal vertical axis (SVA) to determine likelihood of PJK. More recently, other alignment parameters such as thoracic-pelvic angles (TPAs) and age-adjusted alignment have been examined. PURPOSE The goal of this study is to examine the relationship between GAP, TPAs, and bracing with likelihood of developing PJK. STUDY DESIGN/SETTING A retrospective chart review was conducted to identity ASD patients with at least 1 year of radiographic follow up. PATIENT SAMPLE Patients who underwent fusions to the pelvis and >4 levels fused from 2013 to 2018 and have 1-year postoperative alignment x-rays were included. OUTCOME MEASURES The rate of radiographic PJK (change of 10-20°) and severe PJK (change>20°) was determined for each group. Reoperation rates were also collected. METHODS Surgical records were reviewed to determine patient sample. Chart and X-ray review were conducted to determine spinopelvic alignment parameters, GAP scores, bracing, and reoperation. X-rays were reviewed up to one year postoperatively in order to determine PJK. RESULTS A total of 81 patients were included (mean 64y 63%F); baseline and 1-year postoperative alignment did not differ between PJK and no PJK patients. There was no PJK in 53.1%, 30.9% had PJK from 10-20°, and 16% had sPJK. Of these, 7 patients had revision surgery: 1 for PJK and 1 for rod fracture. Postop bracing was used in 54% of patients. There was no difference in sPJK according to brace use. At baseline, 79% of patients had severely disproportioned GAP, 16% moderate, 5% proportioned. Of severely disproportioned, 63% had no change in GAP at 1 year. Improved GAP was not associated with sPJK (improved: 22% vs no change: 18%, p=.72). Greater correction of the UIV-PA was associated with a larger PJK angle change (R=.26) as was the 1 year T1-UIV angle (R=.30), both p .05. CONCLUSIONS There was no correlation between PJK and GAP alone or change in GAP; it is notable that these patients tended to be disproportioned pre and postop. Greater correction of UIV-PA and larger postop T1-UIV was associated with greater PJKA change; suggesting that the greater alignment correction led to greater likelihood of it failing. Our data suggest bracing was not effective in preventing PJK. These parameters may help surgeons understand alignment targets in ASD. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Location of correction within the lumbar spine impacts acute adjacent-segment kyphosis.

OBJECTIVEThe surgical correction of adult spinal deformity (ASD) often involves modifying lumbar lordosis (LL) to restore ideal sagittal alignment. However, corrections that include large changes in LL increase the risk for development of proximal junctional kyphosis (PJK). Little is known about the impact of cranial versus caudal correction in the lumbar spine on the occurrence of PJK. The goal of this study was to investigate the impact of the location of the correction on acute PJK development.METHODSThis study was a retrospective review of a prospective multicenter database. Surgically treated ASD patients with early follow-up evaluations (6 weeks) and fusions of the full lumbosacral spine were included. Radiographic parameters analyzed included the classic spinopelvic parameters (pelvic incidence [PI], pelvic tilt [PT], PI-LL, and sagittal vertical axis [SVA]) and segmental correction. Using Glattes' criteria, patients were stratified into PJK and noPJK groups and propensity matched by age and regional lumbar correction (ΔPI-LL). Radiographic parameters and segmental correction were compared between PJK and noPJK patients using independent t-tests.RESULTSAfter propensity matching, 312 of 483 patients were included in the analysis (mean age 64 years, 76% women, 40% with PJK). There were no significant differences between PJK and noPJK patients at baseline or postoperatively, or between changes in alignment, with the exception of thoracic kyphosis (TK) and ΔTK. PJK patients had a decrease in segmental lordosis at L4-L5-S1 (-0.6° vs 1.6°, p = 0.025), and larger increases in segmental correction at cranial levels L1-L2-L3 (9.9° vs 7.1°), T12-L1-L2 (7.3° vs 5.4°), and T11-T12-L1 (2.9° vs 0.7°) (all p < 0.05).CONCLUSIONSAlthough achievement of an optimal sagittal alignment is the goal of realignment surgery, dramatic lumbar corrections appear to increase the risk of PJK. This study was the first to demonstrate that patients who developed PJK underwent kyphotic changes in the L4-S1 segments while restoring LL at more cranial levels (T12-L3). These findings suggest that restoring lordosis at lower lumbar levels may result in a decreased risk of developing PJK.

Jack-knife Posture After Correction Surgery for Degenerative Sagittal Imbalance—Does Spinopelvic Parameter Always Matter in Preventing Stooping Posture?

Study DesignA retrospective comparative cohort study. ObjectiveTo investigate the causes of jack-knife posture (JKP) without proximal junctional kyphosis (PJK) and to compare the causes of PJK and JKP without PJK. Summary of Background DataPJK causing stooping posture could be inevitable after long instrumented lumbar fusion for degenerative sagittal imbalance. However, few studies have addressed JKP without PJK, which is a different type of sagittal malalignment. MethodsNinety-four adult patients who underwent long instrumented lumbar fusion for degenerative sagittal imbalance were divided into three groups depending on the presence of a postoperative sagittal deformity: JKP, PJK, or none. JKP was defined as a sagittal vertical axis of at least 8 cm anterior to the posterosuperior corner of S1 upper endplate without PJK. PJK was defined as a proximal kyphotic angle ≥10° and at least 10° greater than the preoperative measurement. ResultsSeventeen patients (18.1%) showed JKP, and 39 patients (41.5%) showed PJK. The mean age at the surgery of JKP and PJK patients was 70.0 and 65.5 years, respectively (p = .05). JKP developed more frequently if the preoperative pelvic tilt was <25° or the sagittal vertical axis was >8 cm (p = .048, 0.004, respectively). PJK developed more frequently if the preoperative pelvic tilt was >25°, surgically corrected lumbar lordosis was >30°, or the lumbar lordosis to thoracic kyphosis angle was <0° (p = .002, .010, .031, respectively). JKP was more likely to develop in patients without sacropelvic fixation (p = .042), although they had a more degenerative L5–S1 segment (p = .010). ConclusionsPostoperative sagittal deformity can be classified into two types: JKP and PJK. JKP is caused mainly by hip and back extensor muscle weakness even though the cause of postoperative sagittal decompensation could be multifactorial. However, PJK developed mainly due to spinopelvic malalignment. Therefore, hip and back extensor weakness, which is age-dependent, may explain why older patients experienced more postoperative sagittal deformity. Level of EvidenceLevel IV.

Cervical Alignment Changes in Patients Developing Proximal Junctional Kyphosis Following Surgical Correction of Adult Spinal Deformity.

Proximal junctional kyphosis (PJK) following adult spinal deformity (ASD) surgery is a well-documented complication, but associations between radiographic PJK and cervical malalignment onset remain unexplored. To study cervical malalignment in ASD surgical patients that develop PJK. Retrospective review of prospective multicenter database. Inclusion: primary ASD patients (≥5 levels fused, upper instrumented vertebra [UIV] at T2 or above, and 1-yr minimum follow-up) without baseline cervical deformity (CD), defined as ≥2 of the following criteria: T1 slope minus cervical lordosis < 20°, cervical sagittal vertical axis < 4 cm, C2-C7 cervical lordosis < 10°. PJK presence (<10° change in UIV and UIV + 2 kyphosis) and angle were identified 1 yr postoperative. Propensity score matching between PJK and nonPJK groups controlled for baseline alignment. Preoperative and 1-yr postoperative cervical alignment were compared between PJK and nonPJK patients. One hundred sixty-three patients without baseline CD (54.9 yr, 83.9% female) were included. PJK developed in 60 (36.8%) patients, with 27 (45%) having UIV above T7. PJK patients had significantly greater baseline T1 slope in unmatched and propensity score matching comparisons (P < .05). At 1 yr postoperative, PJK patients had significantly higher T1 slope (P < .001), C2-T3 Cobb (P = .04), and C2-T3 sagittal vertical axis (P = .02). New-onset CD rate in PJK patients was 15%, and 16.5% in nonPJK patients (P > .05). Increased PJK magnitude was associated with increasing T1 slope and C2-T3 SVA (P < .05). Patients who develop PJK following surgical correction of ASD have a 15% incidence of development of new-onset CD. Patients developing PJK following surgical correction of ASD tend to have an increased preoperative T1 slope. Increased progression of C2-T3 Cobb angle and C2-T3 SVA are associated with development of PJK following surgical correction of thoracolumbar deformity.

Friday, September 28, 2018 4:05 PM–5:05 PM abstracts: tumor and deformity: 249. Cervical, thoracic and spinopelvic compensation after proximal junctional kyphosis: Does location of PJK matter?

BACKGROUND CONTEXT Proximal Junctional Kyphosis (PJK) can occur at any segment along the spine and yet, compensation mechanisms at levels proximal to an area of PJK have not clearly been characterized. Understanding compensation mechanisms may help in determining optimal level selection when performing revision surgery for PJK. PURPOSE Evaluate the difference in compensatory mechanisms between thoraco-lumbar and thoracic PJK. STUDY DESIGN/SETTING Retrospective review of prospective database. PATIENT SAMPLE A total of 369 patients out of 496 eligible (73.2%) for 2 years follow-up. OUTCOME MEASURES Radiographic alignment of the cervical and thoracic spine as well as pelvic orientation. METHODS PJK location was based on UIV location: LT (T8–L1) or UT (T1–7). Inclusion criteria were fusion >5 levels with the LIV being S1/Ilium. PJK was defined by Glattes criteria. Alignment parameters were compared between PJK patients separated by UIV Group. Correlation Analysis was made between PJK magnitude and global or cervical alignment within UIV group. Percentage of patient reach criteria for cervical deformity according to cSVA (>4cm) were calculated overall and within each subgroup. RESULTS There were 369 patients included in the analysis; mean age of 63, BMI 28 and 81% female, LT (n=193) versus UT (n=176). The rate of radiographic PJK was 49% and higher in the LT group (55% vs. 42%, p=.01). No significant differences were found in global alignment between PJK patients, with the exception of TK being larger for PJK patients (UT:−49.4 vs. −59.0, LT: −46.5 vs. −56.4; all p CONCLUSIONS PJK location results in different compensation mechanisms of the cervical and thoracic spine. The LT group compensates with an increase in PT and CL to maintain an acceptable cSVA. The UT group increases their CL to counter the increase in T1S but continues to have TS-CL mismatch with an elevated cSVA due to maximum compensation at the cervical level. As a result, increase in cSVA led to 40.3% of patients meeting criteria for CD with focal deformity located in the cervical spine. Future studies should investigate the surgical strategy to treat PJK depending on the location of the focal deformity.

Characteristics and risk factors for proximal junctional kyphosis in adult spinal deformity after correction surgery: a systematic review and meta-analysis.

There are still controversies on characteristics and risk factors for proximal junctional kyphosis (PJK) in adult spinal deformity (ASD) patients. The objective of this study is to explore the characteristics and risk factors for PJK in ASD. A systematic online search in databases including PubMed, EMBASE, Web of Science, and the Cochrane Library was performed to identify eligible studies. OR and weight mean difference with 95% CI were used to evaluate characteristics and risk factors. A total of 31 studies were finally included. ASD patients with PJK had larger proximal junctional angle (PJA), thoracic kyphosis (TK), pelvic incidence minus lumbar lordosis (PI-LL), and sagittal alignment. Age, female gender, and low BMD/osteoporosis were demographic risk factors for PJK. Using hooks at upper instrumented vertebra (UIV) and the selection of UIV above T8 could reduce the occurrence of PJK, while pelvic fixation was significantly associated with increased occurrence of PJK. Preoperative LL, preoperative pelvic tilt (PT), preoperative LL-TK, preoperative PI-LL, preoperative sagittal vertical axis (SVA), preoperative global spine alignment (GSA), postoperative PJA, change in PJA, postoperative TK, change in LL, change in SVA, and postoperative GSA were identified as risk factors for PJK. In conclusion, PJK patients had larger PJA, larger TK, smaller PI-LL, and larger sagittal alignment. Older female ASD patients with low BMD/osteoporosis are more likely to suffer from PJK. We recommend the following: (1) using hooks at UIV; (2) UIV should be chosen above T8, and pelvic fixation should be avoided if possible; (3) ideal correction of sagittal alignment should be performed to prevent the occurrence of PJK.

Clinical and radiographic presentation and treatment of patients with cervical deformity secondary to thoracolumbar proximal junctional kyphosis are distinct despite achieving similar outcomes: Analysis of 123 prospective CD cases

CD development secondary to PJK was recently documented in adult spinal deformity patients after surgical correction for thoracolumbar ASD. This study analyzes surgical management of patients with CD secondary to proximal junctional kyphosis (PJK) versus patients with primary CD. Retrospective review of multicenter cervical deformity (CD) database. CD defined as at least one of the following: C2–C7 coronal Cobb > 10°, cervical lordosis (CL) > 10°, cervical sagittal vertical axis (cSVA) > 4cm, CBVA > 25°. Patients were grouped into those with PJK (UIV +2 < −10°) prior to cervical surgery versus who don’t (Non-PJK). Independent t-tests and chi-squared tests compared radiographic, clinical, and surgical metrics between PJK and non-PJK groups. Of 123 eligible CD patients, 26(21.1%) had radiographic PJK prior to cervical surgery. PJK patients had significantly greater T2–T12 thoracic kyphosis (−58.8° vs −45.0°, p = 0.002), cSVA (49.1 mm vs 38.9 mm, p = 0.020), T1 Slope (42.6° vs 28.4°, p < 0.001), TS-CL (44.1° vs 35.6°, p = 0.048), C2-T3 SVA (98.8 mm vs 75.8 mm, p = 0.015), C2 Slope (45.4° vs 36.0°, p = 0.043), and CTPA (6.4° vs 4.6°, p = 0.005). Comparing their surgeries, the PJK group had significantly more levels fused (10.7 vs 7.4, p = 0.01). There was significantly greater blood loss in PJK patients (1158 ± 1063vs 738 ± 793 cc, p = 0.028); operative time, surgical approach, and BMP-2 use were similar (all p > 0.05). PJK patients experienced higher rates of complications 30 and 90 days post-operatively (23.1% vs. 5.2%, p = 0.004; 30.8% vs. 19.6%, p = 0.026), and more instrumentation failure 30 days postoperatively (7.8% vs. 1.0%, p = 0.004). Patients with cervical deformity secondary to PJK had worse baseline CD, despite no differences in HRQL or demographics. Surgical correction of CD associated with PJK required more invasive surgery and had higher complication rates than non-PJK patients, despite achieving similar clinical outcomes.

Proximal junctional kyphosis in thoracic adolescent idiopathic scoliosis: risk factors and compensatory mechanisms in a multicenter national cohort.

Proximal junctional kyphosis (PJK) is a frequent complication, up to 46%, in adolescent idiopathic scoliosis surgical treatment (AIS). Several risk factors have been evoked but remain controversial. The purpose of this study was to analyze the incidence of PJK in a multicenter cohort of AIS patient and to determine risk factor for PJK. Lenke I and II AIS patients operated between 2011 and 2015 (minimum of 2-years follow-up) were included. On fullspine X-rays, coronal and sagittal radiographic parameters were measured preoperatively, postoperatively and at final follow-up. Occurrence of radiological PJK corresponding to a 10° increase in the sagittal Cobb angle, measured between the upper instrumented vertebra (UIV) and UIV + 2, between postoperative and 2-years follow-up X-rays, was reported. Among the 365 patients included, 15.6% (n = 57) developed a PJK and only 10 patients required a revision surgery. Preoperatively, PJK patients had significantly larger pelvic incidence (57° ± 13° vs. 51° ± 12°), larger lumbar lordosis (LL) (63° ± 12° vs. 57° ± 11°) and bigger C7 slope. Postoperatively (3months), in the non-PJK group, thoracic kyphosis (TK) was increased and LL was not significantly different. However, postoperatively, in the PJK group, no significant change was observed in TK, whereas C7 slope decreased and LL significantly increased. There was also a postoperative change in inflection point which was located at a more proximal level in the PJK group. Between postoperative time and final follow-up, TK and LL significantly increased in the PJK group. PJK is a frequent complication in thoracic AIS, occurring 16%, but remains often asymptomatic (less than 3% of revisions in the entire cohort). An interesting finding is that patients with high pelvic incidence and consequently large LL and TK were more at risk of PJK. As demonstrated in ASD, one of the causes of PJK might be postoperative posterior imbalance that can be due to increased LL, insufficient TK or inflection point shift during surgery. These slides can be retrieved under Electronic Supplementary Material.

Virtual Modeling of Postoperative Alignment After Adult Spinal Deformity Surgery Helps Predict Associations Between Compensatory Spinopelvic Alignment Changes, Overcorrection, and Proximal Junctional Kyphosis.

Retrospective review of a prospective multicenter database. To develop a method to analyze sagittal alignment, free of the influence of proximal junctional kyphosis (PJK), and then compare PJK to non-PJK patients using this method. PJK after adult spinal deformity (ASD) surgery remains problematic as it alters sagittal alignment. The present study proposes a novel virtual modeling technique that attempts to eliminate the confounding effects of PJK on postoperative spinal alignment. A virtual spinal modeling technique was developed on a retrospective ASD cohort of patients with multilevel spinal fusions to the pelvis with at least 2-year postoperative follow-up. The virtual postoperative alignment (VIRTUAL) was created from the postoperative alignment of the instrumented segments and the preoperative alignment of the unfused segments. VIRTUAL was validated by comparisons to actual 2-year postoperative alignment (REAL) in non-PJK patients. Patients were then divided into two groups: PJK and non-PJK based on the presence/absence of PJK at 2 years postoperatively. PJK and non-PJK patients were compared using VIRTUAL and REAL. A total of 458 patients (78F, mean 57.9 yr) were analyzed. The validation of VIRTUAL versus REAL demonstrated correlation coefficients greater than 0.7 for all measures except sagittal vertical axis (SVA; r = 0.604). At 2 years, REAL alignment in PJK patients demonstrated a smaller pelvic incidence minus lumbar lordosis and a larger thoracic kyphosis than non-PJK patients, but similar SVA, T1 pelvic angle, and pelvic tilt. An analysis of VIRTUAL demonstrated that patients with PJK had a smaller pelvic incidence minus lumbar lordosis, pelvic tilt, SVA, and T1 pelvic angle than non-PJK patients (P < 0.05). This technique demonstrated strong correlations with actual postoperative alignment. Comparisons between REAL and VIRTUAL alignments revealed that postoperative PJK may develop partially as a compensatory mechanism to the overcorrection of sagittal deformities. Future research will evaluate the appropriate thresholds for deformity correction according to age and ASD severity. 3.

Age-Adjusted Alignment Goals Have the Potential to Reduce PJK.

Retrospective cohort. To explore proximal junctional kyphosis (PJK) as a function of age-adjusted surgical correction goals. Recent adult spinal deformity (ASD) studies show that alignment targets are age-specific. Despite recognizing age and malalignment as PJK risk factors, no study has assessed the age-specific effects of alignment on PJK. ASD patients with fusions to the pelvis were included and stratified into three groups: young adults (YA <40 years old), middle aged (MA: 40-65 years old), and the elderly (ED >65 years old). Analysis of variance compared the groups with respect to 1-year postoperative alignments and 1-year offsets from age-specific alignment targets. A total of 679 patients were enrolled (mean age = 61 years old, 77% female, body mass index = 28.1). At 1 year postoperatively, there was a significant decrease in pelvic tilt (PT; 29-23°), spinopelvic mismatch (pelvic incidence [PI]-lumbar lordosis [LL]) (28-5°), and sagittal vertical axis (SVA; 110-37 mm); overall incidence of PJK was 45.1%. Stratification by age (YA, n = 28; MA, n = 389; ED, n = 262) revealed an increase in PJK incidence with age: YA = 17.9%, MA = 43.8%, and ED = 50.2% (P < 0.001). PJK patients had smaller postoperative PI-LL mismatches (ED 0.8° vs. 9.8°, MA 3.1° vs. 7.3°) than non-PJK patients, without any significant differences in PT or SVA. Analysis of the postoperative offsets from age-specific norms revealed that PJK patients in the two older subgroups and in the study cohort as a whole were overcorrected as compared to non-PJK patients (PI-LL offset-all: -5.2° vs. 2.8°, MA: -1° vs. +4°, ED: -11° vs. -2°; SVA offset-all: -10 mm vs. 7 mm, MA: -3 mm vs. 10 mm, ED: -18 mm vs. -6 mm). The correlation coefficients between PJK angles and the offsets from age-adjusted objective were small (0.320 for PI-LL, 0.114 for PT, and 0.136 for SVA). Overall, this study suggests that PJK patients were overcorrected when compared to age-adjusted alignment goals. Certainly, elderly patients are subject to independent risk factors for PJK, making the prevention of PJK complex. However, individualized optimization of surgical alignment can improve outcomes. This emphasizes the need for surgeons to incorporate age-specific alignment targets into the standard preoperative planning process. 3.