Distal Junctional Kyphosis Research Articles

Clinical and Radiographic Results in Thoracic Hyperkyphosis Surgical Treatment Considering the Optimal Distal Fusion Area

Introduction: The aim of this retrospective study was to evaluate the clinical and radiographic outcomes of patients who underwent posterior correction and fusion for thoracic hyperkyphosis, with a focus on determining the optimal distal fusion level. Methods: From 2006 to 2012, 26 patients with a median age of 16.8 years (range 14–25), diagnosed with either idiopathic hyperkyphosis or Scheuermann’s kyphosis, underwent posterior fusion and Ponte osteotomies at two medical centers. Radiographic evaluations were performed preoperatively, immediately postoperatively, and at the final follow-up and included assessments of fusion extension, Cobb angle, sagittal balance, and the presence of junctional kyphosis or discopathy. Results: The median follow-up period was 12.3 years (range 11–17). Good clinical outcomes were observed in 24 patients, with no cases of hardware failure. The distal fusion area included the first lordotic vertebra in 17 patients, the sagittal stable vertebra in four patients, and both in five patients. Cobb angle correction was maintained at 50% at the final follow-up (p > 0.05). Significant sagittal balance correction was achieved in 87% of patients immediately postoperatively and was maintained at the final follow-up (p > 0.05). Junctional kyphosis occurred in two patients whose fusion area included only the first lordotic vertebra. Conclusions: Including at least the first lordotic vertebra in the fusion area is crucial for preventing junctional kyphosis. Extending the fusion to the stable vertebra can reduce the incidence of distal junctional kyphosis, especially in symptomatic young adult patients, potentially avoiding the need for revision surgery.

Long-term outcomes of spinal fusion in adolescent idiopathic scoliosis: a literature review

Adolescent idiopathic scoliosis (AIS) is the most common form of spinal deformity in the younger population. The surgical management for these patients improved constantly over the last year and might not be comparable to modern treatment strategies. However, under this aspect the present investigation updates and discusses current evidence regarding the long-term outcome of the surgical management of AIS. All the clinical studies which evaluated the long-term outcomes of spinal fusion were considered. Level of evidence, clinical and radiological data, results of health-related questionnaires and surgery-associated complications during long-term follow-up, e.g., proximal and distal junctional kyphosis (PJK/DJK), and adjacent segment degeneration (ASD), are presented. Data concerning the following patient-reported outcomes measures were collected: Oswestry Disability Index (ODI), Scoliosis Research Society (SRS) Outcome Questionnaire, visual analogue scale (VAS), and short form-12 and 36 (SF-12/SF-36). Overall, data from 1115 patients were included. Of them, 324 underwent anterior and 791 posterior spinal fusion. One study focuses on a combined anterior/posterior fusions. The mean follow-up was 22.6 years (posterior fusion: 24.6 years, anterior fusion: 18.31 years). Seven studies focus on the thoracic segments, while 12 focus on the lumbar spine. Data on imaging was reported in 13 studies and those on PROMs in 15 investigations. In conclusion, there is low quality and paucity of long-term data on AIS. However, the long-term results of the implicated studies on AIS patients in this review appear to be satisfactory, although there are limitations in the outcome compared to healthy comparison cohorts. Adjacent degenerations appear to be the most common mechanical complication after long-segment fusions, despite their influence on the outcome remains unclear. With regard to pregnancies, there are slightly increased cesarean section rates, which could be explained by deviations in the sagittal profile.

Distal Junctional Kyphosis and Failure in Adult Deformity Surgery Down to L5: Commentary on "Distal Junctional Failure After Fusion Stopping at L5 in Patients With Adult Spinal Deformity: Incidence, Risk Factors, and Radiographic Criteria".

Distal Junctional Kyphosis and Failure in Adult Deformity Surgery Down to L5: Commentary on "Distal Junctional Failure After Fusion Stopping at L5 in Patients With Adult Spinal Deformity: Incidence, Risk Factors, and Radiographic Criteria".

A Spinal Realignment Technique for Correction of Adolescent Distal Junctional Kyphosis: 2-Dimensional Operative Video.

A Spinal Realignment Technique for Correction of Adolescent Distal Junctional Kyphosis: 2-Dimensional Operative Video.

Preoperative Planning of Lumbar Lordosis for Adult Degenerative Scoliosis Surgery in the Chinese Population

Pelvic incidence minus lumbar lordosis mismatch (PI-LL) is directly related to poor quality of life in adult degenerative scoliosis (ADS) patients. The purpose of the study was to determine the most appropriate postoperative PI-LL value for patients with ADS. The medical records of patients with ADS in our department were retrospectively collected. The data included age, sex, body mass index, age-adjusted Charlson comorbidity index, osteopenia, length of hospital stay, operative duration, estimated blood loss, American Society of Anesthesiologists score, number of fusion levels, lumbar lordosis, sagittal vertical axis, pelvic incidence, PI-LL, Scoliosis Research Society-22 score, Oswestry Disability Index score, and mechanical complications. A total of 316 patients were enrolled. PI-LL, lumbar lordosis, sagittal vertical axis, Scoliosis Research Society-22 score, Oswestry Disability Index score at the time of last follow-up were 20.7 ± 8.5°, 23.4 ± 14.1°, 4.0 ± 2.1cm, 3.7 ± 0.9, and 18.1 ± 5.5, respectively. In terms of mechanical complications, 88 patients (27.8%), 34 patients (10.8%), and 19 patients (6.0%) had proximal junctional kyphosis, distal junctional kyphosis, and implant-related complications, respectively. In the fully adjusted model, compared with 0 grade PI-LL group and++ grade PI-LL group,+ grade PI-LL group had the best clinical outcomes and the fewest mechanical complications. The stability of these conclusions was verified in sensitivity analyses. Optimal PI-LL value should be 10°-20° after corrective surgery in patients with ADS, which is associated with excellent clinical outcomes and lower complication rates. Previous criteria may be at risk of overcorrection, which may lead to proximal junctional kyphosis.

Is It Possible for Patients with Early Distal Junctional Kyphosis following Adult Cervical Deformity Corrective Surgery to Achieve Similar Outcomes to Their Unaffected Counterparts? An Analysis of Recovery Kinetics.

Background: Distal junctional kyphosis (DJK) is a concerning complication for surgeons performing cervical deformity (CD) surgery. Patients sustaining such complications may demonstrate worse recovery profiles compared to their unaffected peers. Methods: DJK was defined as a >10° change in kyphosis between LIV and LIV-2, and a >10° index angle. CD patients were grouped according to the development of DJK by 3M vs. no DJK development. Means comparison tests and regression analyses used to analyze differences between groups and arelevant associations. Results: A total of 113 patients were included (17 DJK, 96 non-DJK). DJK patients were more sagittally malaligned preop, and underwent more osteotomies and combined approaches. Postop, DJK patients experienced more dysphagia (17.7% vs. 4.2%; p = 0.034). DJK patients remained more malaligned in cSVA through the 2-year follow-up. DJK patients exhibited worse patient-reported outcomes from 3M to 1Y, but these differences subsided when following patients through to 2Y; they also exhibited worse NDI (65.3 vs. 35.3) and EQ5D (0.68 vs. 0.79) scores at 1Y (both p < 0.05), but these differences had subsided by 2Y. Conclusions: Despite patients exhibiting similar preoperative health-related quality of life metrics, patients who developed early DJK exhibited worse postoperative neck disability following the development of their DJK. These differences subsided by the 2-year follow-up, highlighting the prolonged but eventually successful course of many DJK patients after CD surgery.

463 Cervical Vertebral Bone Quality (C-VBQ) Score Independently Predicts Distal Junctional Kyphosis (DJK) Following Posterior Cervical Fusion

INTRODUCTION: Posterior cervical fusion is the surgery of choice when fusing long segments of the cervical spine. However, due to the limited presence of this pathology, there is a paucity of data in the literature about the postoperative complication of distal junctional kyphosis (DJK). METHODS: A retrospective analysis of consecutive set of patients who underwent posterior cervical fusion at a single hospital between June 1, 2010 and May 31, 2020. Univariate analysis was completed between DJK and non-DJK groups, with multivariate regression completed for relevant clinical variables. Simple linear regression was completed to analyze correlation between the C-VBQ score and total degrees of kyphosis angle change. RESULTS: Ninety-three patients were identified, of whom 19 (20.4%) had DJK and 74 (79.6%) did not. The DJK group had a significantly greater number of patients with anemia than the non-DJK group (15.8% vs. 1.4%; P = .03). The DJK group had a significantly higher C-VBQ score than the non-DJK group (2.97 ± 0.40 vs. 2.26 ± 0.46; P &lt; .001). A significant, positive correlation was found between the C-VBQ score and the total degrees of kyphosis angle change (r2 = 0.26, P &lt; .001). On multivariate analysis, the C-VBQ score independently predicted DJK (OR, 1.50; 95% CI, 1.28-1.76; P &lt; .001). CONCLUSIONS: We found that the C-VBQ score was an independent predictive factor of DJK after posterior cervical fusion.

Novel Approach to Difficult Spinal Reconstruction: Bilateral Simultaneous Rib and Iliac Crest Vascularized Bone Graft Spinoplastic Surgery

Summary: Pseudoarthrosis is a severe complication of spinal fusion surgery with occurrence rates as high as 35%–40%. Current options of revision surgery to correct pseudoarthrosis frequently carry high failure rates and risk of developing junctional kyphosis. Pedicled vascularized bone grafts (VBGs) are an innovative approach to boost spinal fusion rates via improving structural integrity and increasing the delivery of blood to the donor site. This versatile technique can be performed at different spinal levels without additional skin incisions and with minimal added operative time. Here we present the first bilateral rib and iliac crest VBG spinoplastic surgery performed to augment spinal fusion in a 68-year-old woman with distal junctional kyphosis and severe positive sagittal balance with low back and neck pain and significant difficulty standing upright. The patient had history of multiple spinal operations with preoperative CT imaging demonstrating loosening and pull out of L3 and fracture of L2 screws. She underwent two-stage surgical treatment involving anterior lumbar interbody fusion L3-S1 followed by removal of hardware, T4 to pelvis fusion with L2-3 prone lateral interbody fusion, and T11-S1 posterior column osteotomies. The surgery was augmented by bilateral rib and iliac crest VBGs performed by plastic surgery. At three-month follow-up the patient demonstrated functional improvement, being able to maintain upright posture and walk; was satisfied with the result of the surgery; and demonstrated no graft-related complications. In conclusion, utilization of pedicled VBGs is a novel, promising approach to augment spinal surgery in high risk patients.

Long-term results of treatment of a patient with basilar invagination complicated by distal kyphosis and compressive ischemic cervical myelopathy: a clinical case and a brief literature review

Objective. To present a clinical case of surgical correction of a craniovertebral anomaly complicated after 8 years by distal junctional kyphosis, stenosis, antelisthesis of the C5 vertebra and compressive ischemic cervical myelopathy in the C5–C6 segment.Material and Methods. When treating a 56-year-old patient with multiple anomalies of the craniovertebral region, differentiated surgical technologies were consistently used due to the development of late complications. The sequence and rationale for surgical decision making is described.Results. Initially, the patient underwent transoral decompression and posterior occipitocervical fixation, and after 8 years - reinstallation of the system with distal extension of the instrumentation zone to the C7 vertebra with indirect posterior decompression of the spinal cord, anterior discectomy with direct decompression and cage fixation at the C5–C6 level. Regression of myelopathic syndrome, correction of orthopedic status and significant improvement in functional status were achieved.Conclusion. A rare clinical observation demonstrates a combination of basilar invagination with assimilation of the atlas, which has provided rationale for two-stage surgical treatment in one surgical session (1st stage – transoral resection of the dens and 2/3 of the C2 vertebral body with anterior decompression of the spinal cord, and 2nd stage – occipitocervical fixation). The use of extended systems in this case caused the development of a clinically significant syndrome of the distal adjacent level, which required repeated surgical treatment after 8 years.

Short-Term Risk Factors for Distal Junctional Kyphosis after Spinal Reconstruction Surgery in Patients with Osteoporotic Vertebrae.

Level 3 retrospective cohort case-control study. This study aimed to investigate the risk factors for distal junctional kyphosis (DJK) caused by osteoporotic vertebral fractures following spinal reconstruction surgery, with a focus on the sagittal stable vertebra. Despite the rarity of reports on DJK in this setting, DJK was reported to reduce when the lower instrumented vertebra (LIV) was extended to the sagittal stable vertebra in the posterior corrective fixation for Scheuermann's disease. This study included 46 patients who underwent spinal reconstruction surgery for thoracolumbar osteoporotic vertebral fractures and kyphosis and were followed up for 1 year postoperatively. DJK was defined as an advanced kyphosis angle >10° between the LIV and one lower vertebra. The patients were divided into groups with and without DJK. The risk factors of the two groups, such as patient background, surgery-related factors, radiographic parameters, and clinical outcomes, were analyzed. The DJK and non-DJK groups included 14 and 32 patients, respectively, without significant differences in patient background. Those with instability in the distal adjacent LIV disc had a significantly higher risk of DJK occurrence (28.6% vs. 3.2%, p=0.027). DJK occurrence significantly increased in those with the sagittal stable vertebra not included in the fixation range (57.1% vs. 18.8%, p=0.020). Other preoperative radiographic parameters were not significantly different. Instability in the distal adjacent LIV disc (adjusted odds ratio, 14.50; p=0.029) and the exclusion of the sagittal stable vertebra from the fixation range (adjusted odds ratio, 5.29; p=0.020) were significant risk factors for DJK occurrence. Regarding spinal reconstruction surgery in patients with osteoporotic vertebral fractures, instability in the distal adjacent LIV disc and the exclusion of the sagittal stable vertebra from the fixation range were risk factors for DJK occurrence in the short term.

Costs of revision operations for distal junctional kyphosis following thoracic posterior spinal fusion for adolescent idiopathic scoliosis

PurposeTo assess direct costs and risks associated with revision operations for distal junctional kyphosis/failure (DJK) following thoracic posterior spinal instrumented fusions (TPSF) for adolescent idiopathic scoliosis (AIS).MethodsChildren who underwent TPSF for AIS by a single surgeon (2014–2020) were reviewed. Inclusion criteria were minimum follow-up of 2 years, thoracolumbar posterior instrumented fusion with a lower instrumented vertebra (LIV) cranial to L2. Patients who developed DJK requiring revision operations were identified and compared with those who did not develop DJK.ResultsSeventy-nine children were included for analysis. Of these, 6.3% developed DJK. Average time to revision was 20.8 ± 16.2 months. Comparing index operations, children who developed DJK had significantly greater BMIs, significantly lower thoracic kyphosis postoperatively, greater post-operative lumbar Cobb angles, and significantly more LIVs cranial to the sagittal stable vertebrae (SSV), despite having statistically similar pre-operative coronal and sagittal alignment parameters and operative details compared with non-DJK patients. Revision operations for DJK, when compared with index operations, involved significantly fewer levels, longer operative times, greater blood loss, and longer hospital lengths of stay. These factors resulted in significantly greater direct costs for revision operations for DJK ($76,883 v. $46,595; p < 0.01).ConclusionsIn this single-center experience, risk factors for development of DJK were greater BMI, lower post-operative thoracic kyphosis, and LIV cranial to SSV. As revision operations for DJK were significantly more costly than index operations, all efforts should be aimed at strategies to prevent DJK in the AIS population.

Are insufficient corrections a major factor in distal junctional kyphosis? A simulated analysis of cervical deformity correction using in-construct measurements.

The present study utilized recently developed in-construct measurements in simulations of cervical deformity surgery in order to assess undercorrection and predict distal junctional kyphosis (DJK). A retrospective review of a database of operative cervical deformity patients was analyzed for severe DJK and mild DJK. C2-lower instrumented vertebra (LIV) sagittal angle (SA) was measured postoperatively, and the correction was simulated in the preoperative radiograph in order to match the C2-LIV by using the planning software. Linear regression analysis that used C2 pelvic angle (CPA) and pelvic tilt (PT) determined the simulated PT that matched the virtual CPA. Linear regression analysis was used to determine the C2-T1 SA, C2-T4 SA, and C2-T10 SA that corresponded to DJK of 20° and cervical sagittal vertical axis (cSVA) of 40 mm. Sixty-nine cervical deformity patients were included. Severe and mild DJK occurred in 11 (16%) and 22 (32%) patients, respectively; 3 (4%) required DJK revision. Simulated corrections demonstrated that severe and mild DJK patients had worse alignment compared to non-DJK patients in terms of cSVA (42.5 mm vs 33.0 mm vs 23.4 mm, p < 0.001) and C2-LIV SVA (68.9 mm vs 57.3 mm vs 36.8 mm, p < 0.001). Linear regression revealed the relationships between in-construct measures (C2-T1 SA, C2-T4 SA, and C2-T10 SA), cSVA, and change in DJK (all R > 0.57, p < 0.001). A cSVA of 40 mm corresponded to C2-T4 SA of 10.4° and C2-T10 SA of 28.0°. A DJK angle change of 10° corresponded to C2-T4 SA of 5.8° and C2-T10 SA of 20.1°. Simulated cervical deformity corrections demonstrated that severe DJK patients have insufficient corrections compared to patients without DJK. In-construct measures assess sagittal alignment within the fusion separate from DJK and subjacent compensation. They can be useful as intraoperative tools to gauge the adequacy of cervical deformity correction.

Risk factors for distal junctional kyphosis after posterior spinal surgery in adolescent idiopathic scoliosis: a meta-analysis.

Distal junctional kyphosis (DJK) is a serious complication after posterior spinal surgery in managing adolescent idiopathic scoliosis (AIS). Our study aims to investigate the predictors of DJK in AIS patients. We searched the English databases of PubMed, Embase, and the Cochrane Library for clinical research studies on AIS. To identify the risk factors for DJK, we collected demographic data, such as age, gender, and body mass index (BMI), and sagittal parameters, including preoperative pelvic tilt (PT), sagittal vertical axis (SVA), lumbar lordosis (LL), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), distal junctional angle (DJA), lowest instrumented vertebrae (LIV) relative to sagittal stable vertebrae (SSV), and postoperative DJA. Data were analyzed by RevMan (5.3 version) and STATA (12.0 version). Finally, six included articles (1,240 patients) showed 9% (98 of 1,240 patients) of patients suffering from DJK. Our findings indicated that preoperative TK [p = 0.007, OR = 0.35, 95% CI (0.10, 0.61)], TLK [p < 0.0001, OR = 5.99, 95% CI (3.33, 8.65)], and postoperative DJA [p = 0.002, OR = 0.56, 95% CI (0.21, 0.91)] in the DJK group were markedly higher than those in the non-DJK group. Moreover, patients with LIV above SSV [p < 0.0001, OR = 7.95, 95% CI (4.16, 15.22)] were more likely to develop DJK. No discernible difference was found in age, sex, BMI, preoperative PT, SVA, LL, or DJA between the two groups. Regarding the AIS patients, factors such as higher preoperative TK and TLK, higher postoperative DJA, and LIV above the SSV were related to an increased rate of DJK.

Cervical Vertebral Bone Quality Score Independently Predicts Distal Junctional Kyphosis After Posterior Cervical Fusion.

Posterior cervical fusion is the surgery of choice when fusing long segments of the cervical spine. However, because of the limited presence of this pathology, there is a paucity of data in the literature about the postoperative complications of distal junctional kyphosis (DJK). We aimed to identify and report potential associations between the preoperative cervical vertebral bone quality (C-VBQ) score and the occurrence of DJK after posterior cervical fusion. The authors retrospectively reviewed records of patients who underwent posterior cervical fusion at a single hospital between June 1, 2010, and May 31, 2020. Patient data were screened to include patients who were >18 years old, had baseline MRI, had baseline standing cervical X-ray, had immediate postoperative standing cervical X-ray, and had clinical and radiographic follow-ups of >1 year, including a standing cervical X-ray at least 1 year postoperatively. Univariate analysis was completed between DJK and non-DJK groups, with multivariate regression completed for relevant clinical variables. Simple linear regression was completed to analyze correlation between the C-VBQ score and total degrees of kyphosis angle change. Ninety-three patients were identified, of whom 19 (20.4%) had DJK and 74 (79.6%) did not. The DJK group had a significantly higher C-VBQ score than the non-DJK group (2.97 ± 0.40 vs 2.26 ± 0.46; P < .001). A significant, positive correlation was found between the C-VBQ score and the total degrees of kyphosis angle change (r 2 = 0.26; P < .001). On multivariate analysis, the C-VBQ score independently predicted DJK (odds ratio, 1.46; 95% CI, 1.27-1.67; P < .001). We found that the C-VBQ score was an independent predictive factor of DJK after posterior cervical fusion.

The Importance of Incorporating Proportional Alignment in Adult Cervical Deformity Corrections Relative to Regional and Global Alignment: Steps Toward Development of a Cervical-Specific Score.

The Global Alignment and Proportion(GAP) Score is widely used in adult spinal deformity surgery. However, it is not specific to the parameters used in adult cervical deformity(ACD). Create a cervicothoracic alignment and proportion(CAP) score in operative ACD patients. Retrospective single-center study. ACD patients with two-year(2Y) data were included. Parameters consisted of: relative McGregor's Slope[RMGS =(MGS*1.5)/0.9], relative cervical lordosis[RCL=CL - Thoracic Kyphosis(TK)], Cervical Lordosis Distribution Index(CLDI=C2-Apex*100/C2-T2), relative pelvic version(RPV=SS - PI*0.59+9), and a frailty factor(greater than 0.33). Cutoff points were chosen where the cross-tabulation of parameter subgroups reached maximal rate of meeting Optimal Outcome. Optimal outcome was defined as meeting Good Clinical Outcome(GCO) criteria without occurrence of distal junctional failure(DJF) or reoperation. CAP was scored between 0-13 and categorized accordingly: ≤3(Proportioned), 4-6(Moderately Disproportioned), >6(Severely Disproportioned). Multivariable logistic regression analysis determined the relationship between CAP categories, overall score and development of distal junctional kyphosis(DJK), DJF, reoperation, and Optimal Outcome by two years. 105 operative ACD patients were included. Assessment of three-month CAP score found a mean of 5.2/13 possible points. There were 22.7% of patients who were proportioned, 49.5% moderately disproportioned, and 27.8% severely disproportioned. DJK occurred in 34.5% and DJF in 8.7% DJF, 20.0% underwent reoperation, and 55.7% achieved Optimal Outcome. Patients severely disproportioned in CAP had higher odds of DJK (OR: 6.0,[2.1-17.7];P=0.001), DJF (OR: 9.7[1.8-51.8];P=0.008), reoperation(OR: 3.3,[1.9-10.6];P=0.011), and lower odds of meeting the optimal outcome(OR: 0.3,[0.1-0.7]; P=0.007) by two years, while Proportioned patients suffered zero occurrences of DJK or DJF. The regional alignment and proportion score is a method of analyzing the cervical spine relative to global alignment and demonstrates the importance of maintaining horizontal gaze, while also matching overall cervical and thoracolumbar alignment to limit complications and maximize clinical improvement.

Selecting the Vertebra above Sagittal Stable Vertebra as the Distal Fusion Level in Scheuermann's Kyphosis: A Prospective Study with a Minimum of 2-Year Follow-Up.

The proper selection of the lower instrumented vertebra (LIV) remains controversial in the surgical treatment of Scheuermann's disease and there is a paucity of studies investigating the clinical outcomes of fusion surgery when selecting the vertebra one level proximal to the sagittal stable vertebra (SSV-1) as LIV. The purpose of this study is to investigate whether SSV-1 could be a valid LIV for Scheuermann kyphosis (SK) patients with different curve patterns. This was a prospective study on consecutive SK patients treated with posterior surgery between January 2018 and September 2020, in which the distal fusion level ended at SSV-1. The LIV was selected at SSV-1 only in patients with Risser >2 and with LIV translation less than 40 mm. All of the patients had a minimum of 2-year follow-up. Patients were further grouped based on the sagittal curve pattern as thoracic kyphosis (TK, n = 23) and thoracolumbar kyphosis (TLK, n = 13). Radiographic parameters including global kyphosis (GK), lumbar lordosis (LL), sagittal vertical axis (SVA), LIV translation, pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) were measured preoperatively, postoperatively, and at the latest follow-up. The intraoperative and postoperative complications were recorded. The Scoliosis Research Society (SRS)-22 scores were performed to evaluate clinical outcomes. A total of 36 patients were recruited in this study, with 23 in the TK group and 13 in the TLK group. In TK group, the GK was significantly decreased from 80.8° ± 10.1° to 45.4° ± 7.7° after surgery, and was maintained at 45.3° ± 8.6° at the final follow-up. While in the TLK group, GK was significantly decreased from 70.7° ± 9.2° to 39.1° ± 5.4° after surgery (p < 0.001) and to 39.3° ± 4.5° at the final follow-up. Meanwhile, despite presenting with different sagittal alignment, significant improvement was observed in LL, SVA, and LIV translation for both TK and TLK groups (p < 0.05). Self-reported scores of pain and self-image in TK group and scores of self-image and function in TLK group showed significant improvement at the final follow-up (all p < 0.05). Distal junctional kyphosis (DJK) was observed in two patients (8.7%) in TK group, and one patient (7.7%) in TLK group. No revision surgery was performed. Selecting SSV-1 as LIV can achieve satisfactory radiographic and clinical outcomes for SK patients with different curve patterns without increasing the risk of DJK. This selection strategy could be a favorable option for SK patients with Risser sign >2 and LIV translation less than 40 mm.

204. Analysis of cost utility of distal junctional kyphosis occurrence after adult cervical deformity surgery: the benefit of prophylaxis and preoperative optimization

204. Analysis of cost utility of distal junctional kyphosis occurrence after adult cervical deformity surgery: the benefit of prophylaxis and preoperative optimization

Which Bone Mineral Density Measure Offers a More Reliable Prediction of Mechanical Complications in Adult Spinal Deformity Surgery: Hounsfield Units or DEXA Scan?

In patients undergoing adult spinal deformity (ASD) surgery, we sought to: (1) determine the relationship between dual-energy x-ray absorptiometry (DEXA)-measured bone mineral density (BMD), T-scores, and Hounsfield units (HU), and (2) compare the ability of DEXA-measured BMD, T-scores, and HU to predict mechanical complications and reoperations. A single-institution retrospective cohort study was undertaken for cases from 2013 to 2017. ≥5-level-fusion, sagittal/coronal deformity, and 2-year follow-up. Multivariable regression controlled for age, body mass index, receiving anabolic medications, and postoperative sagittal vertical axis and pelvic-incidence lumbar-lordosis mismatch. A subanalysis was performed for osteopenic patients (-1 < T-score < -2). Of 145 patients undergoing ASD surgery, 72 (49.6%) had both preoperative DEXA and computed tomography scans. Mean DEXA-measured BMD was 0.91 ± 0.52 g/cm2, mean T-score was -1.61 ± 1.03, and mean HU was 153.5 ± 52.8. While no correlation was found between DEXA-measured BMD and HU (r= 0.17, P= 0.144), T-score and HU had a weakly positive correlation (r= 0.31, P= 0.007). Mechanical complications occurred in 48 (66.7%) patients, including 27 (37.5%) proximal junctional kyphosis (PJK), 1 (1.4%) distal junctional kyphosis, 5 (6.9%) implant failure, 30 (41.7%) rod fracture/pseudarthrosis, 42 (58.3%) reoperations, and 16 (22.2%) reoperations due to PJK. No association was found between DEXA-measured BMD or T-scores with mechanical complications or reoperations. While univariate regression showed a significant association between lower HU and PJK (OR 0.98, 95%CI 0.97-0.99, P= 0.011), the significance was lost after multivariable analysis. When considering osteopenic patients (n= 37), only DEXA-measured BMD was an independent risk factor for PJK (OR 0.01, 95%CI 0.00-0.09, P= 0.017), with a threshold of 0.82 g/cm2 (AUC 0.70, 95%CI 0.53-0.84, P= 0.019). Poor correlation was found between the 3 BMD modalities. DEXA-measured BMD may be superior to T-scores and HU in predicting PJK among patients with osteopenia with a threshold of BMD <0.82 g/cm2.

Are we improving in the optimization of surgery for high-risk adult cervical spine deformity patients over time?

The aim of this study was to investigate whether surgery for high-risk patients is being optimized over time and if poor outcomes are being minimized. Patients who underwent surgery for cervical deformity (CD) and were ≥ 18 years with baseline and 2-year data were stratified by year of surgery from 2013 to 2018. The cohort was divided into two groups based on when the surgery was performed. Patients in the early cohort underwent surgery between 2013 and 2015 and those in the recent cohort underwent surgery between 2016 and 2018. High-risk patients met at least 2 of the following criteria: 1) baseline C2-7 Cobb angle > 15°, mismatch between T1 slope and cervical lordosis ≥ 35°, C2-7 sagittal vertical axis > 4 cm, or chin-brow vertical angle > 25°; 2) age ≥ 70 years; 3) severe baseline frailty (Miller index); 4) Charlson Comorbidity Index (CCI) ≥ 1 SD above the mean; 5) three-column osteotomy as treatment; and 6) fusion > 10 levels or > 7 levels for elderly patients. The mean comparison analysis assessed differences between groups. Stepwise multivariable linear regression described associations between increasing year of surgery and complications. Eighty-two CD patients met high-risk criteria (mean age 62.11 ± 10.87 years, 63.7% female, mean BMI 29.70 ± 8.16 kg/m2, and mean CCI 1.07 ± 1.45). The proportion of high-risk patients increased with time, with 41.8% of patients in the early cohort classified as high risk compared with 47.6% of patients in the recent cohort (p > 0.05). Recent high-risk patients were more likely to be female (p = 0.008), have a lower BMI (p = 0.038), and have a higher baseline CCI (p = 0.013). Surgically, high-risk patients in the recent cohort were more likely to undergo low-grade osteotomy (p = 0.003). By postoperative complications, recent high-risk patients were less likely to experience any postoperative adverse events overall (p = 0.020) or complications such as dysphagia (p = 0.045) at 2 years. Regression analysis revealed increasing year of surgery to be correlated with decreasing minor complication rates (p = 0.030), as well as lowered rates of distal junctional kyphosis by 2 years (p = 0.048). Over time, high-risk CD patients have an increase in frequency and comorbidity rates but have demonstrated improved postoperative outcomes. These findings suggest that spine surgeons have improved over time in optimizing selection and reducing potential adverse events in high-risk patients.

The importance of Hounsfield units in adult spinal deformity surgery: finding an optimal threshold to minimize the risk of mechanical complications.

Low bone mineral density (BMD) is a well-established risk factor for mechanical complications following adult spinal deformity (ASD) surgery. Hounsfield units (HU) measured on computed tomography (CT) scans are a proxy of BMD. In ASD surgery, we sought to: (I) evaluate the association of HU with mechanical complications and reoperation, and (II) identify optimal HU threshold to predict the occurrence of mechanical complications. A single-institution retrospective cohort study was undertaken for patients undergoing ASD surgery from 2013-2017. Inclusion criteria were: ≥5-level fusion, sagittal/coronal deformity, and 2-year follow-up. HU were measured on 3 axial slices of one vertebra, either at the upper instrumented vertebra (UIV) itself or UIV ±4 from CT scans. Multivariable regression controlled for age, body mass index (BMI), postoperative sagittal vertical axis (SVA), and postoperative pelvic-incidence lumbar-lordosis mismatch. Of 145 patients undergoing ASD surgery, 121 (83.4%) had a preoperative CT from which HU were measured. Mean age was 64.4±10.7 years, mean total instrumented levels was 9.8±2.6, and mean HU was 153.5±52.8. Mean preoperative SVA and T1PA were 95.5±71.1 mm and 28.8°±12.8°, respectively. Postoperative SVA and T1PA significantly improved to 61.2±61.6 mm (P<0.001) and 23.0°±11.0° (P<0.001). Mechanical complications occurred in 74 (61.2%) patients, including 42 (34.7%) proximal junctional kyphosis (PJK), 3 (2.5%) distal junctional kyphosis (DJK), 9 (7.4%) implant failure, 48 (39.7%) rod fracture/pseudarthrosis, and 61 (52.2%) reoperations within 2 years. Univariate logistic regression showed a significant association between low HU and PJK [odds ratio (OR) =0.99; 95% confidence interval (CI): 0.98-0.99; P=0.023], but not on multivariable analysis. No association was found regarding other mechanical complications, overall reoperations, and reoperations due to PJK. HU below 163 were associated with increased PJK on receiver operating characteristic (ROC) curve analysis [area under the curve (AUC) =0.63; 95% CI: 0.53-0.73; P<0.001]. Though several factors contribute to PJK, it appears that 163 HU may serve as a preliminary threshold when planning ASD surgery to mitigate the risk of PJK.