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Long, standing radiographs of a patient with kyphoscoliosis who underwent posterior spinal instrumentation using a hookescrew construct at UIV. (A) Postoperative anteroposterior view. (B) Postoperative lateral view.
Source publication
Study Design
Retrospective review.
Objectives
To compare the incidence of proximal junctional kyphosis (PJK) and the clinical, radiographic, and functional outcomes in adults undergoing long posterior spinal fusion with transverse process hooks versus pedicle screws at the uppermost instrumented vertebrae.
Summary of Background Data
Proximal junc...
Context in source publication
Context 1
... the study received approval from The Johns Hopkins University Institutional Review Board, 52 consecutive adult patients were identified from a prospectively accrued cohort who underwent long fusions with TP hooks from 2004 through 2009 ( Figs. 1 and 2) or pedicle screws at the UIV (Fig. 3) and pedicle screws at the remaining levels. All surgeries were performed by the senior author. ...
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Surgical management of severe rigid dystrophic neurofibromatosis (NF) scoliosis is technically demanding and produces varying results. In the current study, we reviewed 9 patients who were treated with combined anterior and posterior fusion using different types of instrumentation (i.e., pedicle screw, hybrid, and all-hook constructs) at our instit...
Citations
... In a retrospective review, it was shown that TPH were associated with a lower incidence of PJK and higher functional scores than pedicle screws [21]. Less rigid construct and decreased amount of damage to the ligaments complex and the capsule of the supra-adjacent facet were proposed Content courtesy of Springer Nature, terms of use apply. ...
Purpose
To assess, in a large population of Adult Spinal Deformity (ASD) patients, the true interest of varying the upper anchors as a protective measure against Proximal Junctional Kyphosis (PJK), by analyzing and comparing 2 groups of patients defined according to their proximal construct. Another objective of the study is to look for any other factors, radiological or clinical, that would affect the occurrence of the proximal failure.
Methods
Retrospective review of a prospective ASD database collected from 5 centers. Inclusion criteria were age of at least 18 years, presence of a spinal deformity with instrumentation from T12 or above to the pelvis, with minimum 2 years of follow-up. Demographic data, spinopelvic parameters, functional outcomes and complications were collected. Multiple logistic regression analysis was performed to identify the risk factors that would affect the occurrence of PJK.
Results
254 patients were included. 166 in the group “screws proximally” (SP) and 88 in the group “hooks proximally” (HP). There was no difference between both groups for PJK (p = 0.967). The occurrence of PJK was rather associated with greater age and BMI, higher preoperative kyphosis, worst preoperative SRS22 and SF36 scores, greater postoperative Sagittal Vertical Axis (SVA), coronal malalignment and kyphosis.
Conclusion
The use of proximal hooks was not effective to prevent PJK after ASD surgery, when compared to proximal screws. Worse preoperative functional outcomes and worse postoperative sagittal and also coronal malalignment were the main drivers for the occurrence of PJK regardless the type of proximal implant.
... Previous biomechanical analyses indicate the importance of less rigid proximal fixation to allow for a more gradual transition to normal biomechanics, thereby reducing the incidence of PJK/PJF [10,70,75,76]. The PJK/PJF prevention strategies based on this notion include (1) the use of the transverse process hooks at the UIV instead of all-pedicle-screw instrumentation to accomplish a less rigid connection to the vertebra [60,69,75,77]; (2) the application of a transition rod that has a short taper to a smaller diameter at the rostral end to dampen the proximal transition forces from the UIV to the non-instrumented vertebrae above [70,75]; and (3) the addition of sublaminar tethers anchored at the UIV and above to reduce adjacent-segment loads [10]. ...
Background and Objectives: Proximal junctional kyphosis (PJK) and failure (PJF), the most prevalent complications following long-segment thoracolumbar fusions for adult spinal deformity (ASD), remain lacking in defined preventive measures. We studied whether one of the previously reported strategies with successful results—a prophylactic augmentation of the uppermost instrumented vertebra (UIV) and supra-adjacent vertebra to the UIV (UIV + 1) with polymethylmethacrylate (PMMA)—could also serve as a preventive measure of PJK/PJF in minimally invasive surgery (MIS). Materials and Methods: The study included 29 ASD patients who underwent a combination of minimally invasive lateral lumbar interbody fusion (MIS-LLIF) at L1-2 through L4-5, all-pedicle-screw instrumentation from the lower thoracic spine to the sacrum, S2-alar-iliac fixation, and two-level balloon-assisted PMMA vertebroplasty at the UIV and UIV + 1. Results: With a minimum 3-year follow-up, non-PJK/PJF group accounted for fifteen patients (52%), PJK for eight patients (28%), and PJF requiring surgical revision for six patients (21%). We had a total of seven patients with proximal junctional fracture, even though no patients showed implant/bone interface failure with screw pullout, probably through the effect of PMMA. In contrast to the PJK cohort, six PJF patients all had varying degrees of neurologic deficits from modified Frankel grade C to D3, which recovered to grades D3 and to grade D2 in three patients each, after a revision operation of proximal extension of instrumented fusion with or without neural decompression. None of the possible demographic and radiologic risk factors showed statistical differences between the non-PJK/PJF, PJK, and PJF groups. Conclusions: Compared with the traditional open surgical approach used in the previous studies with a positive result for the prophylactic two-level cement augmentation, the MIS procedures with substantial benefits to patients in terms of less access-related morbidity and less blood loss also provide a greater segmental stability, which, however, may have a negative effect on the development of PJK/PJF.
... Patient-related, surgical, and biomechanical risk factors for PJK and PJF have been studied extensively, as have a number of strategies for prevention. 17,23,25,[29][30][31][32][33][34][35][36][37][38][39] Nevertheless, the optimal revision strategy for patients who have already experienced PJF, in order to prevent recurrent failure, remains unknown. Patients who have already experienced proximal junctional failure are at an inherently higher risk of experiencing the same phenomenon again following revision surgery, with recurrence rates estimated at 44%. 20 This at-risk population requires special consideration in order to prevent a cascading pattern of multiple surgeries resulting in more and more proximal fusion levels and associated increases in morbidity and mortality. ...
Study design
Retrospective review of a prospectively-collected multicenter database.
Objectives
The objective of this study was to determine optimal strategies in terms of focal angular correction and length of proximal extension during revision for PJF.
Methods
134 patients requiring proximal extension for PJF were analyzed in this study. The correlation between amount of proximal junctional angle (PJA) reduction and recurrence of proximal junctional kyphosis (PJK) and/or PJF was investigated. Following stratification by the degree of PJK correction and the numbers of levels extended proximally, rates of radiographic PJK (PJA >28° & ΔPJA >22°), and recurrent surgery for PJF were reported.
Results
Before revision, mean PJA was 27.6° ± 14.6°. Mean number of levels extended was 6.0 ± 3.3. Average PJA reduction was 18.8° ± 18.9°. A correlation between the degree of PJA reduction and rate of recurrent PJK was observed (r = −.222). Recurrent radiographic PJK (0%) and clinical PJF (4.5%) were rare in patients undergoing extension ≥8 levels, regardless of angular correction. Patients with small reductions (<5°) and small extensions (<4 levels) experienced moderate rates of recurrent PJK (19.1%) and PJF (9.5%). Patients with large reductions (>30°) and extensions <8 levels had the highest rate of recurrent PJK (31.8%) and PJF (16.0%).
Conclusion
While the degree of focal PJK correction must be determined by the treating surgeon based upon clinical goals, recurrent PJK may be minimized by limiting reduction to <30°. If larger PJA correction is required, more extensive proximal fusion constructs may mitigate recurrent PJK/PJF rates.
... Increasing the fixation force at the LIV can also reduce implant-related failures [21]. In some cases, such as in case 3, the screw was not cut out because a hook was used at the LIV. ...
Study Design: Level 3 retrospective cohort case-control study.Purpose: 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.Overview of Literature: 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.Methods: 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.Results: 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.Conclusions: 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.
... It has been shown in previous studies that pedicle screws are mechanically superior to hooks in three-dimensional correction of spinal deformity (17,39). In terms of PJK, although there are studies reporting that there is no significant difference in terms of PJK between patients with pedicle screws and hooks instrumentation (21), there are many studies which show that the incidence of PJK is lower in patients with proximal hooks (12,13). ...
Aim:
To evaluate the occurrence of proximal junctional kyphosis (PJK) as well as both the clinical and radiologic outcomes of patients who underwent surgery for Scheuermann?s Kyphosis (SK) using either exclusively pedicle screws or a combination of proximal hooks and pedicle screws constructs.
Material and methods:
Surgically treated 37 patients with the diagnosis of SK were evaluated retrospectively. The patients were divided into two groups based on the type of instrumentation employed. The first group contained 22 patients with only pedicle screws (PP) while the second group consisted of 15 patients with mixed constructs that were proximal hooks and pedicle screws (HP) at the rest of the levels. The clinical and radiological data were compared in patients who were followed up for a minimum of 2 years.
Results:
The average duration of follow-up for the PP group was approximately 94.7 ± 53.1 months, whereas the HP group had an average follow-up period of around 103 ± 64.4 months. After conducting the analyses, no statistically significant findings were identified in the measurements taken for the SRS-22 scores in preoperative, postoperative, and the most recent follow-up radiographs (p > 0.05). It is worth noting that among patients who exclusively utilized pedicle screws, both the proximal (p=0.045) and distal (p=0.030) junctional kyphosis angles experienced more pronounced increases compared to hybrid structures.
Conclusion:
While no notable distinction was observed between the two groups, patients with pedicle screws fixation had a higher PJK angle. Conversely, the use of hooks at the upper end seems to be a preventive measure against the development of PJK.
... The use of spinal hooks versus pedicle screws at upper instrumented sites has been explored, as more rigid anchor types have been associated with the development of PJK. Hooks were shown to significantly reduce the incidence of PJK compared to pedicle screws and were thought to better accommodate the dynamic post-operative forces placed on an instrumented spine [146][147][148][149]. Utilizing age-adjusted spinopelvic alignment goals further prevented overcorrection and stress placed on junctional sites [150]. ...
Background:
Surgical intervention is a critical tool to address adult spinal deformity (ASD). Given the evolution of spinal surgical techniques, we sought to characterize developments in ASD correction and barriers impacting clinical outcomes.
Methods:
We conducted a literature review utilizing PubMed, Embase, Web of Science, and Google Scholar to examine advances in ASD surgical correction and ongoing challenges from patient and clinician perspectives. ASD procedures were examined across pre-, intra-, and post-operative phases.
Results:
Several factors influence the effectiveness of ASD correction. Standardized radiographic parameters and three-dimensional modeling have been used to guide operative planning. Complex minimally invasive procedures, targeted corrections, and staged procedures can tailor surgical approaches while minimizing operative time. Further, improvements in osteotomy technique, intraoperative navigation, and enhanced hardware have increased patient safety. However, challenges remain. Variability in patient selection and deformity undercorrection have resulted in heterogenous clinical responses. Surgical complications, including blood loss, infection, hardware failure, proximal junction kyphosis/failure, and pseudarthroses, pose barriers. Although minimally invasive approaches are being utilized more often, clinical validation is needed.
Conclusions:
The growing prevalence of ASD requires surgical solutions that can lead to sustained symptom resolution. Leveraging computational and imaging advances will be necessary as we seek to provide comprehensive treatment plans for patients.
... Attention is increasingly being drawn to prophylactic measures, such as vertebroplasty, cement augmentation, and the implementation of hooks, transitional rods, or sublaminar tethering (Table 1). 19,23,50,[58][59][60][61][62][63][64][65][66][67] ...
... This could involve using larger or longer pedicle screws, adding additional screws or hooks, posterior laminar tethering, or using cement augmentation to decrease the integrity of the posterior ligamentum complex. 19,23,50,[58][59][60][61][62][63] ...
Adult spinal deformity (ASD) surgery aims to correct abnormal spinal curvature in adults, leading to improved functionality and reduced pain. However, this surgery is associated with various complications, one of which is proximal junctional failure (PJF). PJF can have a significant impact on a patient’s quality of life, necessitating a comprehensive understanding of its causes and the development of effective management strategies. This review aims to provide an in-depth understanding of PJF in ASD surgery. PJF is a complex complication resulting from a multitude of factors including patient characteristics, surgical techniques, and postoperative management. Age, osteoporosis, overcorrection of sagittal alignment, and poor bone quality are identified as significant risk factors. The clinical implications of PJF are substantial, often requiring revision surgery and causing a considerable decrease in patients’ quality of life. Prevention strategies include careful preoperative planning, appropriate patient selection, and optimization of surgical techniques. Treatment often necessitates a multifaceted approach, including surgical intervention and the management of underlying risk factors. Predictive modeling is an emerging field that may offer a promising avenue for the risk stratification of patients and individualized preventive strategies. A thorough understanding of PJF’s pathogenesis, risk factors, and clinical implications is essential for surgeons involved in ASD surgery. Current preventive measures and treatment strategies aim to mitigate the risk and manage the complications of PJF, but the complication cannot be entirely prevented. Future research should focus on the development of more effective preventive and treatment strategies, and predictive models could be valuable in this pursuit.
... Protective factors to prevent PJK are discussed a lot, including soft tissue protection, cement augmentation, ligamentous augmentation, hybrid instrumentation, such as hook, and adequate selection of UIV [2,3,30]. In most studies, a significant reduction of PJK by gradual transitional zone at the top of the construct is observed and overall data showed that the use of hooks, tension bands, and tethers can make a softer loading zone, create less rigidity, and in comparison, hooks are the best technique to distribute forces at the proximal end of the instrument and reduce the risk of PJK eventually [30][31][32][33][34][35][36][37]. It can improve ROM and flexibility within the UIV and make a smooth transitional zone. ...
... 2. Gradual-transitional zone on the proximal end of instrumented construct: Many studies have been conducted to gradually reduce the forces on the top of the instrumentation using hooks and diminish the stiffness between rigid-instrumented-spine and mobile-non-instrumented-spine on the top [36,37]. ...
Background and Aim: This study aims to provide information about the common complications of adult spinal deformity (ASD) surgery that requires revision surgery and proximal junctional kyphosis (PJK) as the most common complication. We emphasized crucial protective factors that reduce the risk of post-operative PJK, especially the careful selection of the upper instrumented vertebra (UIV) and gradual transitional zone on the proximal end of the construct. Methods and Materials/Patients: This study is a retrospective review of the adult population with spinal deformity who underwent posterior instrumentation surgery and requires revision surgery due to post-operative complications, such as disc herniation, screw loosening, rod breakage, distal junctional failure, and symptomatic PJK. Fifteen ASD patients requiring revision surgery were included. We evaluated the ratio of age, gender, the prevalence of postoperative complications, and the most common complication of PJK based on Cobb angle and patient symptoms. Results: This study included 15 patients with ASD who underwent posterior spinal instrumentation surgery and experienced post-operative complications requiring revision surgery. As a result, 6 patients out of 15 (40%) had PJK, four patients (26.6%) had disc herniation and canal stenosis, two patients (13.3%) had screw loosening, one patient (6.6%) had rod breakage and two patients (13.3%) had distal junctional failure required revision surgery. Conclusion: In our study, PJK is at the top of the complications and two risk factors have a great impact on predisposing ASD surgery to the post-operative PJK, that is, the UIV level, and gradual transitional zone at the proximal end of the construct, therefore the risk of this unfortunate outcome can be significantly minimized by carefully selecting UIV and hooks using a smooth gradual transitional zone along with other protective factors.
... [1][2][3] Based on current research, the incidence of PJK is as high as 40%. 1,2,[4][5][6][7][8][9] As the pathogenesis and clinical course of PJK were more heavily investigated, recent studies reveal that rather than a single entity, PJK represents a spectrum of radiographic and clinical diseases that can adversely affect patient outcomes and quality of life. 8,10 Most of the time, PJK can be successfully diagnosed within the first few months postoperatively, making this a complication that should be detected and followed early before it causes symptoms. ...
Study design:
Retrospective review.
Objective:
This bibliometric review summarizes the publication trends and critical information about the most cited Proximal Junction Kyphosis (PJK) articles.
Background:
Data: Proximal junctional kyphosis is frequently diagnosed after spinal fusion surgery. However, there continues to be heavy debate regarding the definition, incidence, risk factors, and treatment of this disorder.
Methods:
Nine hundred eleven articles were found when searching The Web of Science database with the keywords "Proximal junctional kyphosis" and "proximal junctional failure." The 200 top-cited articles were reviewed and screened to ensure PJK was discussed. The articles were filtered based on the highest to lowest number of citations, and the top 50 articles were chosen. Inclusion criteria included articles that contained a discussion of PJK and outcomes after surgery. Exclusion criteria included articles without mentioning PJK, or that studied non-human subjects. The 50 most cited articles were sorted by level of evidence and their classification for analysis.
Results:
The 50 most cited articles in this study were published a total of 6056 times. These articles were cited 71-413 times in the literature, with publications from 1994 to 2018. Most of the top 50 articles (64%) were published in the USA. Specifically, HSS and Washington University are the institutions with the most contributions to the publication of the most cited articles on PJK (n = 16). Lenke was the author that contributed to most publications in the top 50 articles on PJK.
Conclusion:
This study provides a framework for the most cited articles published on PJK. Most articles on this topic were in the category of clinical outcomes (36%) and were of a level of evidence III (46%). Most of the top-cited articles came from the journal Spine (68%) and were published in the USA (64%). These top-cited papers are essential to understanding this critical trending topic in spine surgery.
Level of evidence:
III.
... Thus, PJK has a higher incidence in the osteoporotic population [1,13]. However, studies have shown that the use of cement augmentation in adjacent vertebral bodies during long-segment fusion surgery is effective in preventing the occurrence of PJK [14][15][16]. Hart et al. [17] reported that patients with cement augmentation of vertebral bodies had a lower probability of PJK. Similarly, Martin et al. [14] found that cement augmentation at the upper instrumented vertebra (UIV) and proximal instrumented vertebra (UIV + 1) reduced the incidence of PJK. ...
PurposeThe purpose of this study was to compare the biomechanical effects of cement-reinforced vertebrae at different levels and with different volumes of cement in preventing proximal junction kyphosis (PJK) after long-segment fusion.
Methods
Models were established of T11-S1 performing posterior thoracolumbar fusion, different segmental bone cement enhancements and different volume bone cement enhancement to analyze the biomechanical effects of bone cement enhancement on the vertebrae.ResultsIn the single-level cement reinforcement groups, the maximum Mises stress of cancellous bone decreased observably only in the cement-reinforced segment, and the trend of reduction was the same as that of the two-levels group. In the two-level (T10 and T11) cement reinforcement group, the maximum Mises stress of T10 cancellous bone decreased by 17.8%, 17.6%, 7.8%, 6.2%, 21.1% and 7.3%, respectively, and that of T11 cancellous bone decreased by 4.3%, 18.8%, 13.7%, 20.9%, 32.5% and 28.8% under the postures of flexion, extension, lateral bending and axial rotation. Secondly, there was no observable difference in the maximum Mises stress in the vertebral cancellous bone between the 2 ml, 3 ml and 4 ml bone cement models. Furthermore, there was no observable effect of bone cement enhancement of the vertebrae on the intradiscal pressure in adjacent segments.Conclusion
The preventive effect of two-level bone cement-reinforced vertebrae on PJK was better. Secondly, injecting a little cement could reduce vertebral stress and the incidence of leakage.
