Proximal Junctional Failure Research Articles

The Association of Bone Mineral Density with Distal Junctional Kyphosis and Distal Junctional Failure After Multilevel Spine Fusions: A Systematic Review and Meta-Analysis.

Distal junctional kyphosis (DJK) and distal junctional failure (DJF) are known complications of adult multilevel spinal fusion surgery. Previous literature has extensively investigated proximal junctional kyphosis and proximal junctional failure, but DJK and DJF are relatively understudied. This study investigates the association between bone mineral density (BMD) and DJK/DJF via a systematic review and meta-analysis. A literature search was conducted across PubMed, Cochrane, Web of Science, Embase, and Scopus to find studies reporting DJK, DJF, and BMD. A 12-month minimum follow-up and radiographic biomarker for BMD (Hounsfield units [HU] or a T-score) individually reported for each patient type were required for inclusion. Studies that did not report individualized biomarkers but provided averaged estimates of the effect of BMD on DJK/DJF development were used for systematic review. Our search yielded 12 unique studies with 1094 patients, of which 5 studies with a total of 519 patients were suitable for comparison by meta-analysis. Patients who developed DJK/DJF had significantly lower HUs (113.17±33.86) than patients who did not develop DJK/DJF (142.51±41.39). No significant difference was found with regard to dual-energy X-ray absorptiometry measurements, age, or body mass index between patients who did and did not develop DJK/DJF. Patients who developed DJK/DJF had significantly lower computed tomography-measured HU as compared to those without DJK/DJF. Our findings highlight the potential importance of BMD evaluation with computed tomography prior to multilevel spine fusion surgery, though further research would be helpful to evaluate the significance of dual-energy X-ray absorptiometry-based BMD measurements on DJK/DJF development.

Proximal Junctional Failure Development Despite Achieving Ideal Sagittal Correction According to Age-Adjusted Alignment Target in Patients With Adult Spinal Deformity: Risk Factor Analysis of 196 Cases Undergoing Low Thoracic to Pelvic Fusion

Objective: To identify the risk factors for proximal junctional failure (PJF) after adult spinal deformity (ASD) surgery despite ideal sagittal correction according to age-adjusted alignment target.Methods: The study included patients who underwent low thoracic to pelvic fusion for ASD and obtained ideal correction according to age-adjusted pelvic incidence minus lumbar lordosis. PJF was defined either radiographically as a proximal junctional angle (PJA) of >28° plus a difference in PJA of >22° or clinically as revision surgery for proximal junctional complications. Clinical and radiographic variables were assessed to identify the risk factors for PJF.Results: The final study cohort consisted of 196 patients, of whom 170 were women (86.7%), with an average age of 68.3 years. During mean follow-up duration of 45.9 months, PJF occurred in 43 patients (21.9%). Multivariate logistic regression analysis revealed that old age (odds ratio [OR], 1.063; 95% confidence interval [CI], 1.001–1.129; p=0.046), large preoperative sagittal vertical axis (OR, 1.007; 95% CI, 1.001–1.013; p=0.024), nonuse of a transverse process (TP) hook (OR, 5.556; 95% CI, 1.205–19.621; p=0.028), and high lumbar distribution index (LDI) (OR, 1.136; 95% CI, 1.109–1.164; p<0.001) were significant risk factors for PJF development.Conclusion: A sizeable proportion of patients (21.9%) developed PJF despite achieving ideal sagittal correction. Using TP hooks with avoiding excessive LDI can be helpful to further mitigate the risk of PJF development in this patient group.

Risk Factors, Biomechanics, and Prevention Strategies for Proximal Junctional Failure in Adult Spinal Deformity Surgery – A Commentary on “Proximal Junctional Failure Development Despite Achieving Ideal Sagittal Correction According to Age-Adjusted Alignment Target in Patients With Adult Spinal Deformity: Risk Factor Analysis of 196 Cases Undergoing Low Thoracic to Pelvic Fusion”

Risk Factors, Biomechanics, and Prevention Strategies for Proximal Junctional Failure in Adult Spinal Deformity Surgery – A Commentary on “Proximal Junctional Failure Development Despite Achieving Ideal Sagittal Correction According to Age-Adjusted Alignment Target in Patients With Adult Spinal Deformity: Risk Factor Analysis of 196 Cases Undergoing Low Thoracic to Pelvic Fusion”

New Insights Into Risk Factors for Proximal Junctional Failure in Adult Spinal Deformity Surgery – A Commentary on “Proximal Junctional Failure Development Despite Achieving Ideal Sagittal Correction According to Age-Adjusted Alignment Target in Patients With Adult Spinal Deformity: Risk Factor Analysis of 196 Cases Undergoing Low Thoracic to Pelvic Fusion”

New Insights Into Risk Factors for Proximal Junctional Failure in Adult Spinal Deformity Surgery – A Commentary on “Proximal Junctional Failure Development Despite Achieving Ideal Sagittal Correction According to Age-Adjusted Alignment Target in Patients With Adult Spinal Deformity: Risk Factor Analysis of 196 Cases Undergoing Low Thoracic to Pelvic Fusion”

Surgical Management of Vertebral Body Fractures in Proximal Junctional Kyphosis: A Case Series Utilizing Intravertebral Reduction Devices and Hardware Extension

Vertebral body fracture is the most common manifestation of proximal junctional failure (PJF), a frequent complication following adult spinal deformity surgery and a leading cause of reoperation(1). In the absence of established consensus regarding optimal revision techniques for PJF, this case report presents two patients with non-traumatic vertebral fractures secondary to PJF, successfully managed with intravertebral reduction device (SpineJack®) and bone cement augmentation, combined with the extension of previous instrumentation. While the etiology of PJF in these two cases remains undetermined, this report aims to contribute to the evolving literature on surgical revision strategies for PJF, particularly in the context of vertebral fractures. The first case involves a 62-year-old female with degenerative scoliosis, flat back deformity, adult idiopathic scoliosis, coronal malalignment, and degenerative disc disease with lateral listhesis underwent lateral lumbar interbody fusion (LLIF) at L2-3, L3-4, and L4-5 with titanium interbody devices and posterior L1 to pelvis instrumentation and fusion. Following L1 compression fracture at the proximal end of the instrumentation, the patient underwent surgical revision at 6 weeks postoperative. The pedicle screws at L1 were explanted, and the pedicle tracks were utilized for open placement of SpineJack® implants under fluoroscopic guidance to reduce and elevate the compressed L1 vertebra, restoring anterior vertebral height. The postoperative course was unremarkable, and the patient exhibited significant clinical improvement. The second case involves a 60-year-old female patient with a history of painful thoracolumbar scoliosis who underwent a T8-Pelvis posterior spinal fusion (PSF) with multiple Smith-Petersen osteotomies (SPOs) and L4-S1 transforaminal lumbar interbody fusion (TLIF) with right-sided instrumentation. Following discovery of a T8 vertebral compression fracture at 8 weeks postoperative, existing hardware at the fracture level was removed, and SpineJack® implants were inserted bilaterally into T8, under fluoroscopic direction. The patient’s postoperative course was unremarkable with significant clinical improvement in pain and neurological function. This report aims to contribute to the literature on surgical strategies for managing vertebral fractures associated with PJF. The use of SpineJack® with cement augmentation appears effective in restoring vertebral body height and spinal alignment while offering a less invasive alternative to more extensive procedures like vertebral column resection (VCR). This technique may offer promising results for spine surgeons addressing vertebral fractures in the context of PJF. While the limitations inherent to case reports preclude establishment of intravertebral reduction devices with cement augmentation as a standard clinical practice guideline for vertebral fractures in the setting of proximal junctional kyphosis and/or failure (PJK/PJF), the successful treatment of two patients with this combined approach aims to contribute to the existing literature by presenting the safety and efficacy of such a technique. It suggests its potential utility for spine surgeons encountering this PJF vertebral fractures moving forward.

Comparative Analysis of Outcomes in Adult Spinal Deformity Patients with Proximal Junctional Kyphosis or Failure Initially Fused to Upper Versus Lower Thoracic Spine.

Background: Patients with proximal junctional kyphosis (PJK) or failure (PJF) may demonstrate disparate outcomes and recovery when fused to the upper (UT) versus lower (LT) thoracic spine. Few studies have distinguished the reoperation and recovery abilities of patients with PJK or PJF when fused to the upper (UT) versus lower (LT) thoracic spine. Methods: Adult spine deformity patients ≥ 18 yrs with preoperative and 5-year (5Y) data fused to the sacrum/pelvis were included. The rates of PJK, PJK revision, and radiographic PJF were compared between patients with upper instrumented vertebra (UIV) in the upper thoracic spine (UT; T1-T7) and lower thoracic spine (LT; T8-L1). Mean differences were assessed via analyses of covariance, factoring in any differences between cohorts at baseline and any use of PJF prophylaxis. Backstep logistic regressions assessed predictors of achieving Smith et al.'s Best Clinical Outcomes (BCOs) and complications, controlling for similar covariates. Results: A total of 232 ASD patients were included (64.2 ± 10.2 years, 78% female); 36.3% were UT and 63.7% were LT. Postoperatively, the rates of PJK for UT were lower than LT at 1Y (34.6 vs. 50.4%, p = 0.024), 2Y (29.5 vs. 49.6% (p = 0.003), and 5Y (48.7 vs. 62.8%, p = 0.048), with comparable rates of PJF. In total, 4.0% of UT patients underwent subsequent reoperation, compared to 13.0% of LT patients (p = 0.025). A total of 6.0% of patients had recurrent PJK, and 3.9% had recurrent PJF (both p > 0.05). After reoperation, UT patients reported higher rates of improvement in the minimum clinically important difference for ODI by 2Y (p = 0.007) and last follow-up (p < 0.001). While adjusted regression revealed that, for UT patients, the minimization of construct extension was predictive of achieving BCOs by last follow-up (model p < 0.001), no such relationship was identified in LT patients. Conclusions: Patients initially fused to the lower thoracic spine demonstrate an increased incidence of PJK and lower rates of disability improvement, but are at a lessened risk of neurologic complications if reoperation is required.

Male patients with adult spinal deformity: sex differences in demographics, radiography, and complications.

This study aimed to investigate sex-related differences in demographics, radiography, and perioperative complications in adult spinal deformity (ASD) surgeries. This retrospective cohort, single-center study enrolled patients who underwent long-instrumented fusion from the thoracic spine to the ilium for ASD, with a minimum follow-up of 2years. The incidence of preoperative comorbidities, perioperative complications, and postoperative mechanical complications was analyzed. Of the 323 patients, ASD was more common in females (85.8%). The T-score in female patients was lower than that in male patients (-1.6 ± 1.1 vs.- 0.8 ± 1.0, p = 0.02). Male patients demonstrated lower rates of degenerative kyphoscoliosis (83.4% vs. 65.2%, p = 0.004) but higher rates of neuromuscular disease (7.6% vs. 21.7%, p = 0.003) than female patients. Male patients exhibited higher prevalence of cardiovascular disease (4.0% vs. 13.5%, p = 0.034) and hemodialysis (2.5% vs. 10.8%, p = 0.035). Additionally, male patients had a higher Charlson Comorbidity Index than female patients (0.8 ± 1.1 vs. 1.4 ± 1.1, p = 0.001). Moreover, male patients showed higher perioperative complications in surgical site infection (5.1% vs. 15.2%, p = 0.018). However, the incidence of proximal junctional failure (43.3% vs. 39.1%, p = 0.595) and rod fracture (27.8% vs. 26.1%, p = 0.81) was not different. Male patients with ASD demonstrated frequent pathology of neuromuscular disease, preoperative comorbidities, and surgical site infection, necessitating careful preoperative checkups and intraoperative care.

Incidence and Risk Factors of Recurrent Proximal Junctional Failure in Adult Spinal Deformity Surgery.

Retrospective cohort study. This study aimed to examine the incidence and risk factors for recurrent proximal junctional failure (R-PJF) in adult spinal deformity (ASD) surgery. Among 482 patients receiving ≥ five-level fusion to the pelvis for ASD, 60 patients who underwent fusion extension surgery for PJF were included in the study cohort. R-PJF was defined as the performance of re-revision surgery after revision surgery for PJF. Various clinical and radiographic variables were compared between no R-PJF and R-PJF groups. Stepwise multivariate logistic analysis was performed to identify the risk factors for R-PJF. Of the 60 patients, there were 51 women (85.0%) and 9 men (15.0%) with a mean age of 72.4 ± 6.7 years. The mean fusion length at the index surgery was 7.3 ± 1.6 levels and an average of 4.1 ± 1.3 levels was extended during the revision surgery. Among them, R-PJF developed in 17 patients (28.3%). Multivariate analysis revealed that overcorrection relative to age-adjusted pelvic incidence (PI) - lumbar lordosis (LL) at the index surgery and high total sum of proximal junctional kyphosis severity scale (PJKSS) at the revision surgery were significant risk factors for R-PJF development. The cutoff value for the PJKSS sum was calculated as 8.5 points. R-PJF was developed in 17 patients (28.3%). PI-LL overcorrection should be avoided during the index surgery to mitigate the R-PJF. In addition, timely surgical intervention is required in patients with PJF, considering that the PJF severity tends to increase over time.

Pedicle Subtraction Osteotomies for Surgical Correction of Fixed Sagittal Imbalance: A Meta-Analysis and Systematic Review.

Disruption of the spine's sagittal balance is associated with significant negative impacts on quality of life. Compared with other spinal osteotomies, pedicle subtraction osteotomy (PSO), which can potentially offer greater correction, is considered technically challenging and performed at lower rates. The aim of this study was to review the use of PSO to correct fixed sagittal imbalance and assess its efficacy and associated perioperative complications. In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, the PubMed, EBSCO host, MEDLINE, and Google Scholar databases were queried for full-text English manuscripts published from 1961 to 2022, exploring PSO for the management of fixed sagittal imbalance. Studies were included if they reported preoperative and postoperative radiographic measurements. The mean Methodological Index for Nonrandomized Studies (MINORS) for included articles was 9.6 ± 1.1. The outcomes of interest included etiology, operative time, blood loss, complications, radiographic outcomes, and patient-reported outcomes. Statistical analysis was performed using a random-effects, inverse variance-weighted meta-analysis of observational data. Pre and postoperative radiographic and clinical outcomes were compared using a Student t -test. Fourteen studies with 595 patients were included. Meta-analysis showed that the mean operative time was 7.2 ± 2.0 hours, and the average blood loss was 2033 ± 629 mL. After PSO, there was a significant improvement in sagittal vertebral axis (12.41-3.92 cm, P = .0003), LL (13.35°-42.60°, P = .000002), PSO angle (5.11° to -26.91°, P = .0001), and Oswestry Disability Index (55.36-27.35, P = .02). Common complications include pseudarthrosis (8.1%), neurological deficits (7.8%), and proximal junctional failure (6.0%). PSO offers significant correction of sagittal vertebral axis, lumbar lordosis, PSO angle, and Oswestry Disability Index scores despite its reduced utilization in recent years. Blood loss and high complication rates must be considered when evaluating the efficacy of this procedure; however, surgeon experience and operative techniques can be used to reduce morbidity.

Spontaneous multilevel lumbar pediculolysis associated with spondylolysis: a rare case and review of the literature

BackgroundPediculolysis is bone hypertrophy and pseudoarthrosis caused by pedicle fracture and has often been combined with contralateral spondylolysis in previous reports. Multilevel pediculolysis with spondylolysis is extremely rare, and we report a case who underwent surgery. Cases of multisegment pediculolysis were reviewed to inspire the diagnosis and treatment of similar pathological phenomena.Case presentationA 55-year-old man suffering from low back pain and sciatica was admitted to hospital after failing conservative treatment. The imaging studies revealed bilateral pediculolysis at L3 and L4 and right spondylolysis at L5. When L2-5 internal fixation and fusion surgery were performed, the symptoms improved immediately after surgery. At the 2-year postoperative follow-up, proximal junctional failure appeared and progressively worsened.ConclusionsMultilevel pediculolysis often requires surgical intervention, and segment instability is an important consideration in the development of surgical fusion strategies. The etiology of pediculolysis is still complex and unknown, and the spondylolysis protocol can be used as a reference for treatment. Surgeons should be cautious in surgical planning to minimize the likelihood of postoperative instrumentation failure.

Have We Made Advancements in Optimizing Surgical Outcomes and Enhancing Recovery for Patients With High-Risk Adult Spinal Deformity Over Time?

The spectrum of patients requiring adult spinal deformity (ASD) surgery is highly variable in baseline (BL) risk such as age, frailty, and deformity severity. Although improvements have been realized in ASD surgery over the past decade, it is unknown whether these carry over to high-risk patients. We aim to determine temporal differences in outcomes at 2 years after ASD surgery in patients stratified by BL risk. Patients ≥18 years with complete pre- (BL) and 2-year (2Y) postoperative data from 2009 to 2018 were categorized as having undergone surgery from 2009 to 2013 [early] or from 2014 to 2018 [late]. High-risk [HR] patients met ≥2 of the criteria: (1) ++ BL pelvic incidence and lumbar lordosis or SVA by Scoliosis Research Society (SRS)-Schwab criteria, (2) elderly [≥70 years], (3) severe BL frailty, (4) high Charlson comorbidity index, (5) undergoing 3-column osteotomy, and (6) fusion of >12 levels, or >7 levels for elderly patients. Demographics, clinical outcomes, radiographic alignment targets, and complication rates were assessed by time period for high-risk patients. Of the 725 patients included, 52% (n = 377) were identified as HR. 47% (n = 338) had surgery pre-2014 [early], and 53% (n = 387) underwent surgery in 2014 or later [late]. There was a higher proportion of HR patients in Late group (56% vs 48%). Analysis by early/late status showed no significant differences in achieving improved radiographic alignment by SRS-Schwab, age-adjusted alignment goals, or global alignment and proportion proportionality by 2Y (all P > .05). Late/HR patients had significantly less poor clinical outcomes per SRS and Oswestry Disability Index (both P < .01). Late/HR patients had fewer complications (63% vs 74%, P = .025), reoperations (17% vs 30%, P = .002), and surgical infections (0.9% vs 4.3%, P = .031). Late/HR patients had lower rates of early proximal junctional kyphosis (10% vs 17%, P = .041) and proximal junctional failure (11% vs 22%, P = .003). Despite operating on more high-risk patients between 2014 and 2018, surgeons effectively reduced rates of complications, mechanical failures, and reoperations, while simultaneously improving health-related quality of life.

Frail patients require instrumentation of a more proximal vertebra for a successful outcome after surgery for adult spine deformity.

The aim of this study was to investigate the impact of the level of upper instrumented vertebra (UIV) in frail patients undergoing surgery for adult spine deformity (ASD). Patients with adult spinal deformity who had undergone T9-to-pelvis fusion were stratified using the ASD-Modified Frailty Index into not frail, frail, and severely frail categories. ASD was defined as at least one of: scoliosis ≥ 20°, sagittal vertical axis (SVA) ≥ 5 cm, or pelvic tilt ≥ 25°. Means comparisons tests were used to assess differences between both groups. Logistic regression analyses were used to analyze associations between frailty categories, UIV, and outcomes. A total of 477 patients were included (mean age 60.3 years (SD 14.9), mean BMI 27.5 kg/m2 (SD 5.8), mean Charlson Comorbidity Index (CCI) 1.67 (SD 1.66)). Overall, 74% of patients were female (n = 353), and 49.6% of patients were not frail (237), 35.4% frail (n = 169), and 15% severely frail (n = 71). At baseline, differences in age, BMI, CCI, and deformity were significant (all p = 0.001). Overall, 15.5% of patients (n = 74) had experienced mechanical complications by two years (8.1% not frail (n = 36), 15.1% frail (n = 26), and 16.3% severely frail (n = 12); p = 0.013). Reoperations also differed between groups (20.2% (n = 48) vs 23.3% (n = 39) vs 32.6% (n = 23); p = 0.011). Controlling for osteoporosis, baseline deformity, and degree of correction (by sagittal age-adjusted score (SAAS) matching), frail and severely frail patients were more likely to experience mechanical complications if they had heart failure (odds ratio (OR) 6.6 (95% CI 1.6 to 26.7); p = 0.008), depression (OR 5.1 (95% CI 1.1 to 25.7); p = 0.048), or cancer (OR 1.5 (95% CI 1.1 to 1.4); p = 0.004). Frail and severely frail patients experienced higher rates of mechanical complication than 'not frail' patients at two years (19% (n = 45) vs 11.9% (n = 29); p = 0.003). When controlling for baseline deformity and degree of correction in severely frail and frail patients, severely frail patients were less likely to experience clinically relevant proximal junctional kyphosis or failure or mechanical complications by two years, if they had a more proximal UIV. Frail patients are at risk of a poor outcome after surgery for adult spinal deformity due to their comorbidities. Although a definitively prescriptive upper instrumented vertebra remains elusive, these patients appear to be at greater risk for a poor outcome if the upper instrumented vertebra is sited more distally.

Comparative advantages of activities with lumbosacral preservation for adult spinal deformity surgery: a retrospective Japanese cohort study.

Retrospective cohort study. This study aimed to demonstrate the advantages of preservation of the lumbosacral segment (LSS) in adult spinal deformity (ASD) surgery. Sacroiliac foundation enables sufficient restoration in ASD surgery; however, it could result in poor mobility. Thus, whether LSS provides better activities is still unknown. Among 399 patients who underwent ASD surgery, 62 (≥5 levels fused, >2-year follow-up) underwent fusion from T9-10 to L5 (group L, n=21) or to S2-alar-iliac (group S, n=41). Spinal alignments, Scoliosis Research Society (SRS)-22 scores, performance of activities (clipping toenail, wiping buttock, and wearing socks), proximal and distal junctional failure (PJF+DJF), rod fractures (RFs), and overall revision rates (RRs) were compared between the groups. Group L included younger patients and had longer follow-ups when compared with group S. Although the preoperative pelvic incidence and SRS sagittal modifiers were better in group L, postoperative spinal restorations were nonpathological in both groups. Both groups showed similar deformity progression at the 2-year follow-up; however, group L had lower SRS-22 pain scores. Although "wiping buttocks" did not differ between the groups, the performance of "clipping toenails" and "wearing socks" was poorer in group S at 2 years (possible, group S; 40% vs. group L; 85%-90%). The RRs did not differ between the groups; however, the PJF+DJF rate was higher in group L. DJF was not observed in group S, but occurrence of RFs was noted. Although poorer SRS-22 pain scores might be related to lumbosacral mobility, sufficient restoration, equivalent deformity progression, and similar RRs with better activity imply that lumbosacral preservation should be considered in younger patients with moderate deformities.

The Association Between Hounsfield Units and Mechanical Failure in ASD Patients.

Retrospective Cohort Study. Low bone mineral density (BMD) is a known risk factor for revision surgery in patients with adult spinal deformity (ASD). Hounsfield units (HUs) on CT scans have been suggested as a proxy for assessing BMD. This study aimed to determine HUs in the lumbar region and their association with mechanical failure in patients undergoing ASD surgery. We included ASD patients undergoing surgery from 2010-2020 with minimum 2-year follow-up. We excluded patients without preoperative CT scans, or a CT scan more than 1year before surgery. Mechanical failure was defined as proximal junctional failure, pseudarthrosis, or implant failure requiring revision surgery. On preoperative CT scans, HUs were measured on 3 axial slices on each vertebra from L1-L5 and, if available, at UIV and UIV + 1. We included 170 patients, mean age 63 (±12) years, with 108 (64%) females, and 13 [IQR 10-16] instrumented levels. Mechanical failure occurred in 27% (n = 46) of patients at 2-year follow-up. Mean lumbar HUs were 146 (±51) in the mechanical failure group and 135 (±52) in those without revision (P = .232). Area under the curve was 0.58 (95% CI: 0.48-0.68), corresponding to no to low discriminatory power in predicting mechanical failure using lumbar HUs. Univariate logistic regression revealed no significant difference between mechanical failure and lumbar HUs (OR = 1.00, 95% CI: 1.00-1.01, P = .239). We found no association between mechanical failure and HUs on preoperative CT scans in ASD patients. Thus, we cannot recommend using HUs to predict mechanical failure in these patients.

Incidence and Risk Factors of Proximal Junctional Complications and Rod Fractures After Long-Segment Fusion Surgery With Anterior Column Realignment for Adult Spinal Deformity: A Minimum 2-Year Follow-Up.

To investigate the incidence and risk factors of proximal junctional kyphosis (PJK), proximal junctional failure (PJF), and rod fractures in patients undergoing long-segment (≥4 levels) fusion surgery with anterior column realignment (ACR) for adult spinal deformity. Patients aged ≥60 years with at least a 2-year follow-up were grouped based on PJK, PJF, and rod fracture occurrence. Patient, surgical, and radiographic factors were compared to identify risk factors for these complications. Independent risk factors were identified using univariate and multivariate logistic regression. Among 106 patients, the incidence rates of PJK, PJF, and rod fractures were 15.1%, 28.3%, and 17.9%, respectively. PJK was significantly associated with fewer fusion levels (odds ratio [95% CI], 0.30 [0.13-0.69]), a cranially directed uppermost instrumented vertebra (UIV) screw angle (1.40 [1.13-1.72]), postoperative overcorrection of age-adjusted pelvic incidence-lumbar lordosis (LL) (7.22 [1.13-45.93]), and a large increase in thoracic kyphosis (1.09 [1.01-1.17]). PJF risks were associated with a cranial UIV screw orientation (1.23 [1.09-1.39]), overcorrection of age-adjusted pelvic incidence-LL (10.80 [2.55-45.73]), and a smaller change in sacral slope (0.87 [0.80-0.94]). For rod fractures, prominent factors included a greater number of fusion levels (1.70 [1.17-2.46]), a larger postoperative LL (1.07 [1.01-1.15]), a smaller postoperative thoracic kyphosis (0.92 [0.86-0.98]), and smaller changes in sacral slope (0.73 [0.58-0.92]) and pelvic tilt (0.72 [0.56-0.91]). The incidence and risk factors of PJK, PJF, and rod fractures were similar to those observed in previous studies on long-segment fusion surgery without ACR. The number of ACR levels was not a significant risk factor for PJK, PJF, or rod fractures. When performing deformity correction using ACR, surgeons should carefully consider the direction of the UIV screw and ensure that overcorrection is avoided.

What if You Could Treat the Same Patient Again, Would You do the Exact Same Spine Surgery? A Multi-Surgeon Survey of Their Own Revisions.

Case-based survey. This study aims to investigate what a group of surgeons learned from their own revisions, and what they would do differently today. A multi-center database of ASD surgical patients was queried to identify those with at least 2 surgical procedures performed by the same surgeon between 2009 and 2019. A clinical vignette was created for each case including demographics, a timeline of events, radiographs/measurements, patient-reported outcomes, complications, and surgical strategies used for the index and revision surgeries. The operative surgeon was then asked to fill out a five-question survey aimed at determining factors that contribute to operative decision-making and planning. 86 patients were operated on by 6 participating surgeons for both index and revision ASD surgery. The revised patients had similar follow-up compared to the non-revised group (P = 0.73), with the most common complications indicating a need for revision surgery being proximal junctional failure (42%) and pseudoarthrosis (28%). Surgeons reported that they would not change their surgical strategy in 52.3% of the cases. The leading cause for revision was hardware/instrumentation issues (24.4%). Learning points included rod-related choice (23.3%), level selection (19.8), PJF prophylactic strategy (15.1%), and sagittal alignment objective (11.6%). Surgeons saw opportunity in nearly half of the cases to improve outcomes by changing something in the original surgery. While 40% of the failures remained unexplained from the surgeons' perspective, this study highlights the capacity for adopting changes in adult spinal deformity surgery and illuminates the reasoning behind certain surgical decisions.

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

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

Different characteristics between acute and delayed proximal junctional failure in elderly patients undergoing corrective surgery for adult spinal deformity: comparative analysis of risk factor, failure mode, and clinical consequences

Background contextWhile numerous studies have been conducted on proximal junctional failure (PJF), the clinical significance of acute and delayed PJF remains poorly understood. PurposeThe primary object of this study is to investigate the risk factors separately for acute and delayed PJF. Secondly, we aim to assess the incidence of each failure mode and their clinical consequences in relation to acute and delayed PJF. Study design/settingRetrospective comparative study. Patient samplePatients aged ≥60 years who underwent deformity correction with ≥5-level fusion to sacrum. Outcome measuresRisk factor, failure modes, and patient-reported outcome measure (PROM) MethodsAcute PJF is defined as PJF occurring within 6 months, while delayed PJF occurring after 6 months. Risk factors were analyzed by comparing various clinical and radiographic parameters among three groups: no, acute, and delayed PJF groups. The failure modes, including soft tissue failure, vertebral fracture, fixation failure, and myelopathy, were compared among these groups. The clinical subsequences after PJF development were evaluated by assessing the change in proximal junctional angle (PJA), revision rate, and patient-reported outcome measure (PROM). ResultsA study cohort of 363 patients was included in the analysis. Among them, 156 patients experienced PJF, with 87 patients (55.8%) in the acute PJF group and 69 patients (44.2%) in the delayed PJF group. Multivariate analyses showed that older age (Odds ratio [OR] = 1.057, 95% confidence interval [CI] = 1.002 – 1.118), osteoporosis (OR=2.149, 95% CI = 1.074 – 4.300), high American Society of Anesthesiology ASA score (OR=2.150, 95% CI = 1.089 – 4.245), and overcorrection relative to the age-adjusted pelvic incidence - lumbar lordosis target (OR=4.031, 95% CI = 1.962 – 8.280) were identified as risk factors for the development of acute PJF. On the other hand, a high body mass index (OR=1.150, 95% CI = 1.049 – 1.251) and an uppermost instrumented vertebra located at ≤ T10 (OR=2.267, 95% CI = 1.205 – 4.268) were found to be associated with delayed occurrence of PJF. No radiographic parameters were found to be related to the development of delayed PJF. In terms of failure modes, vertebral fracture and fixation failure were more commonly observed in acute PJF, while soft tissue failure and myelopathy were more predominant in delayed PJF. The clinical course was more aggressive in the acute PJF group compared to the delayed PJF group, as evidenced by a greater increase in PJA, a higher revision rate, and worse PROM. ConclusionsThis study demonstrated different risk factors between the acute and delayed PJF. It was found that overcorrection relative to the age-adjusted PI-LL target increased the risk of acute PJF, but had no impact on the development of delayed PJF. Therefore, a different surgical strategy needs to be established to mitigate both acute and delayed PJF.

Prediction of proximal junctional kyphosis and failure after corrective surgery for adult spinal deformity: an MRI-based model combining bone and paraspinal muscle quality metrics

BACKGROUNDProximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are common complications observed after adult spinal deformity (ASD) surgery and major cause for unplanned reoperations. In addition to spinal alignment, osteoporosis and paraspinal muscle (PSM) degeneration are reportedly indispensable factors that account for PJK/PJF. PURPOSETo investigate the utility of the preoperative risk assessment model using MRI-based skeletomuscular metrics in predicting PJK and/or PJF(PJK/PJF) after ASD correction. STUDY DESIGNRetrospective case-control study. PATIENT SAMPLEConsecutive series of 149 patients at a single academic institution. OUTCOME MEASURESMRI-based measurements of vertebral bone quality at upper instrumented vertebra (VBQ-U) score and fat infiltration rate (FI%) of paraspinal muscle (PSM). METHODSWe performed a retrospective analysis of patients with ASD who underwent ≥5-segment fusion. The vertebral bone quality (VBQ) scoring system was used to assess the bone quality. The PSM quality including FI% and cross-sectional area (CSA) was evaluated. Multivariate logistic regression was performed to determine potential risk factors of PJK/PJF. RESULTSOf 149 patients who underwent ASD surgery, PJK/PJF was found in 45(30.2%). Mean VBQ-U scores were 3.45±0.64 and 3.00±0.56 for patients with and without PJK/PJF (p<.001). Mean FI% of PSM(L3/L4) was 27.9±12.8 and 20.7±13.3 for patients with and without PJK/PJF (p<.001). On multivariate analysis, the VBQ-U score and FI% of PSM were significant independent predictors of PJK/PJF. The AUC for the novel risk assessment model is 0.806, with a predictive accuracy of 86.7%. CONCLUSIONIn patients undergoing ASD correction, paraspinal muscle and vertebral bone quality significantly outweigh radiographic alignment parameters in predicting PJK/PJF. The MRI-based risk assessment model offers a valuable tool for early assessing individualized risk for PJK/PJF.

Effects of pelvic fixation strategies and multi-rod constructs on biomechanics of the proximal junction in long thoracolumbar posterior instrumented fusions: a finite-element analysis.

To assess the effect of various pelvic fixation techniques and number of rods on biomechanics of the proximal junction of long thoracolumbar posterior instrumented fusions. A validated spinopelvic finite-element (FE) model was instrumented with L5-S1 ALIF and one of the following 9 posterior instrumentation configurations: (A) one traditional iliac screw bilaterally ("2 Iliac/2 Rods"); (B) T10 to S1 ("Sacral Only"); (C) unilateral traditional iliac screw ("1 Iliac/2 Rods"); (D) one traditional iliac screw bilaterally with one midline accessory rod ("2 Iliac/3 rods"); (E) S2AI screws connected directly to the midline rods ("2 S2AI/2 Rods"); and two traditional iliac screws bilaterally with two lateral accessory rods connected to the main rods at varying locations (F1: T10-11, F2: T11-12, F3: T12-L1, F4: L1-2) ("4 Iliac/4 Rods"). Range of motions (ROM) at T10-S1 and T9-T10 were recorded and compared between models. The T9-T10 intradiscal pressures and stresses of the T9-10 disc's annulus in addition to the von Mises stresses of the T9 and T10 vertebral bodies were recorded and compared. For T10-S1 ROM, 4 iliac/4 rods had lowest ROM in flexion and extension, while 2 S2AI/2 rods showed lowest ROM in rotation. Constructs with 3 or 4 rods had lower stresses on the primary rods compared to 2-rod constructs. At the proximal adjacent disc (T9-10), 4 iliac/4 rods showed lowest ROM, lowest intradiscal pressures, and lowest annular stress in all directions (most pronounced in flexion-extension). Under flexion and extension, 4 iliac/4 rods also showed the lowest von Mises stresses on the T10 vertebral body but the highest stresses on the T9 vertebral body. Dual iliac screws with 4 rods across the lumbosacral junction and extending to the thoracolumbar junction demonstrated the lowest T10-S1 ROM, the lowest adjacent segment disc (T9-T10) ROM, intradiscal pressures, and annular stresses, and the lowest UIV stresses, albeit with the highest UIV + 1 stresses. Additional studies are needed to confirm whether these biomechanical findings dictate clinical outcomes and effect rates of proximal junctional kyphosis and failure.