Junctional spinal disorders in operated adult spinal deformities: present understanding and future perspectives

Offset sublaminar hook is an efficient tool for the prevention of distal junctional failure after kyphotic deformity correction

PURPOSE

To assess the radiological outcomes and complications focusing on distal junctional failure (DJF) of adult spinal deformity patients who underwent thoracolumbar fixation with the use of offset sublaminar hooks (OSH) distally.

METHODS

Retrospective review of a prospective, multicenter adult spinal deformity database (2 sites). Inclusion criteria were age of at least 18 years, presence of a spinal deformity with thoraco-lumbar instrumentation ending distally with OSH (pelvis excluded), with minimum 2 years of follow-up. Demographic data, spinopelvic parameters, functional outcomes and complications were collected. Data was analyzed using descriptive statistics. Statistical significance was set to p < 0.05.

RESULTS

32 patients met the inclusion criteria, with the main etiologies being Scheuermann kyphosis and post-traumatic kyphosis. There was a significant correction of thoracic or thoraco-lumbar kyphosis (from 83° to 45° in case of posterior column osteotomy, p < 0.001, and from 49° to 11° in case of a three-column osteotomy, p < 0.001). DJF occurred in 9.3% of the patients including 1 patient who presented distal hook dislodgement and 2 patients who presented a compression fracture below the lowest instrumented vertebra. Oswestry Disability Index score improved in the majority of the patients (from 34.3 to 18.1, p < 0.05).

CONCLUSIONS

This is the first paper to propose offset sublaminar hook as a safe and efficient tool for protection of the distal end of the construct in kyphotic ASD surgery when not going down to the pelvis. It showed satisfactory radiological and clinical outcome with an acceptable rate of complications and no distal junctional failure that required revision surgery.

Effects of spinal deformities on lower limb kinematics during walking: a systematic review and meta-analysis

Spinal deformities characterized by malalignment of the spinal column, including scoliosis, hyper kyphosis, and lordosis, can significantly impact lower limb kinematics, potentially leading to altered gait patterns. We aimed to synthesize existing literature investigating the effect of spinal deformities on lower limb kinematics during walking. We searched Four databases including PubMed, Web of Science, Scopus and Embase from their inception through 29th December 2024. The Newcastle-Ottawa Scale was applied to assess quality of included studies and the Grading of Recommendations Assessment, Development and Evaluation (GRADE system) was employed to assess the overall quality of the evidence in the meta-analysis. Mean differences and 95% confidence intervals (CI) were calculated with random effects model in RevMan version 5.4. The review included 35 studies with 1941 participants. Regarding scoliosis, strong evidence suggested a significant increase in right leg stance% and non-significant changes in left leg cadence, right and left leg speed and ankle transverse ROM in individuals with scoliosis compared to controls. Sensitivity analysis showed strong evidence of decrease in right leg stride length and ankle sagittal ROM, decrease in left leg single support and non-significant change in left leg step length. Individuals with sagittal malalignment showed strong evidence of significant reduction in velocity; moderate evidence suggested a significant increase in double support and a decrease in stride length, knee and hip sagittal ROM. Sensitivity analysis revealed strong evidence of a significant decrease in cadence during walking in individuals with sagittal trunk malalignment compared to controls. Participants with adult spinal deformity exhibited strong evidence of increased double support and decreased cadence during walking compared to controls. Spinal deformities significantly alter lower limb kinematics during gait. Our findings highlight the essential need for clinicians to take gait alterations into account when developing targeted interventions for individuals with spinal deformity.

Correlation Between Sagittal Balance and Mechanical Distal Junctional Failure in Degenerative Pathology of the Spine: A Retrospective Analysis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

This study aimed to investigate the failure of the caudal end of lumbar posterior fixation in terms of pre-operative and post-operative spinopelvic parameters, correction performed, demographic and clinical data.

METHODS

The lumbar, thoraco-lumbar and lumbo-sacral posterior fixations performed with pedicle screws and rods in 2017-2019 were retrospectively analyzed. As 81% failures occurred within 4 years, an observational period of 4 years was chosen. The revision surgeries due to the failure in the caudal end were collected in the junctional group. Fixations which have not failed were gathered in the control group. The main spinopelvic parameters were measured for each patient on standing lateral radiographs with the software Surgimap. Demographic and clinical data were extracted for both groups.

RESULTS

Among the 457 patients who met the inclusion criteria, the junctional group included 101 patients, who required a revision surgery. The control group collected 356 primary fixations. The two most common causes of revision surgeries were screws pullout (57 cases) and rod breakage (53 cases). SVA, PT, LL, PI-LL and TPA differed significantly between the two groups (P = .021 for LL, P < .0001 for all the others). The interaction between the two groups and the pre-operative and post-operative conditions was significant for PT, SS, LL, TK, PI-LL and TPA (P < .005). Sex and BMI did not affect the failure onset.

CONCLUSIONS

Mechanical failure is more likely to occur in patients older than 40 years with a thoraco-lumbar fixation where PT, PI-LL and TPA were not properly restored.

Application of Transverse Process Hooks at Distal Thoracic Vertebrae in Uppermost Vertebral Instrumentation for Adult Spinal Deformity Surgery: Special Focus on Delayed-Onset Neurologic Deficits

OBJECTIVE

We aimed to investigate the incidence of delayed-onset neurological deficits (DONDs), DOND-related reoperation rates following adult spinal deformity (ASD) surgery, and efficacy of transverse process hooks (TPHs) at the uppermost instrumented vertebra (UIV) compared to pedicle screws (PSs).

METHODS

We included 90 consecutive patients who underwent instrumented fusion from the sacrum to the distal thoracic spine for ASD, with a minimum follow-up of 24 months. Clinical and radiological outcomes were compared between 33 patients in the TPH group and 57 patients in the PS group, using the Scoliosis Research Society-22 Outcomes questionnaire (SRS-22), Medical Outcomes Study Questionnaire Short-Form 36 (SF-36), and various spinal sagittal parameters.

RESULTS

While absent in the TPH group, myelopathy occurred in 15.8% of the PS group, wherein 15 patients underwent reoperation. The change in the proximal junctional angle, from the pre- to postoperative assessment, was lower in the TPH group than in the PS group (0.2 vs. 6.6, p=0.002). Postoperative facet degeneration in the PS group progressed more significantly than in the TPH group (0.5 vs. 0.1, p=0.002). Surgical outcomes were comparable for both groups, except for the back visual analogue scale (3.5 vs. 4.1, p=0.010) and SRS-22 domains, including pain and satisfaction (3.3 vs. 2.9, p=0.033; 3.7 vs. 3.3, p=0.041). No intergroup difference was observed in SF-36.

CONCLUSION

Using TPHs at the UIV level can prevent DOND, and thereby prevent postoperative myelopathy that necessitates reoperation; thus, TPHs is preferable over PSs in ASD surgery.

Osteoporosis Treatment and Outcomes in Patients Undergoing Adult Spinal Deformity Surgery

BACKGROUND

This study aims to evaluate the prevalence and treatment of osteoporosis in patients undergoing long spinal fusion for adult spinal deformity (ASD) and compare the impact of osteoporosis treatment on surgical and radiographic outcomes.

METHODS

We conducted a retrospective study of adult patients aged ≥40 years who underwent thoracolumbar ASD surgery at a single academic center between 2015 and 2021. We recorded demographic information, procedural details, and pharmacologic treatments. Primary outcomes included preoperative and postoperative sagittal vertical axis, pelvic incidence-lumbar lordosis mismatch, and postoperative complications such as surgical site infection, pseudarthrosis, proximal junctional kyphosis (PJK), and proximal junctional failure. Patients with osteoporosis were compared to those without.

RESULTS

Among 168 patients, the prevalence of osteoporosis was 28.6%. Osteoporotic patients were older and predominantly female. At the time of surgery, 70.8% of osteoporotic patients were receiving pharmacologic treatment. Preoperative pelvic incidence-lumbar lordosis mismatch and sagittal vertical axis did not differ significantly between osteoporotic and nonosteoporotic cohorts. Both cohorts showed similar postoperative improvements. The osteoporotic cohort had a higher rate of PJK (35.4% vs. 17.5%, p=0.01), but no significant difference in proximal junctional failure rates. No significant differences were found between monotherapy and combination therapy outcomes for osteoporotic patients.

CONCLUSIONS

Osteoporotic patients undergoing ASD surgery exhibited similar surgical outcomes and alignment improvements compared to nonosteoporotic patients, despite a higher rate of PJK. Pharmacological treatment appears beneficial in managing osteoporosis-related surgical risks. These findings highlight the importance of identifying and treating osteoporosis in ASD patients to minimize complications.

Hardware failure following multilevel posterior percutaneous fixation using the minimally invasive antepsoas (MIS-ATP) approach in adult spine deformity

Background

Adult spinal deformities (ASDs) requiring long fusions to the lumbosacral junction are notorious for L5-S1 pseudarthrosis and hardware-related complications. The minimally invasive surgery antepsoas (MIS-ATP) technique allows for substantial anterior column reconstruction thereby reducing the risk of posterior hardware-related complications. This study investigates the incidence of posterior hardware-related complications following long-segment fusion (seven or more vertebrae) using MIS-ATP and posterior percutaneous fixation (PPF).

Methods

This is a retrospective review of patients who underwent long spinal fusion (MIS-ATP + PPF) to the sacrum and pelvis for the management of ASD between 2008 and 2019. Postoperative clinical complications and radiographic parameters were collected and analyzed. The following postoperative variables were collected: surgical site infections, neuro-vascular injuries, implant fracture, implant displacement, hardware prominence and related pain, pseudarthrosis, junctional disease (proximal and distal), and need for surgical revision.

Results

A total of 143 patients were included in this study. The most common indications for fusion included: degenerative scoliosis (76.9%) and degenerative spondylolisthesis (17.5%). The average number of fused vertebrae per individual was 8.7. The most common levels fused were: T12-S1 anterior/T10-S1 posterior (53.1%). Forty-four patients (30.8%) experienced a total of 48 complications: pseudarthrosis (2.1%), deep infections (4.2%), painful iliac hardware (5.6%), pedicle screw complications (6.3%), and proximal junctional disease (PJD) (9.8%). Of these, 30 patients (21%) required revision surgery, mostly due to PJD (8 patients; 5.6%).

Conclusions

Long spinal fusions to the sacrum and pelvis are technically challenging and notorious for hardware failure (HF) and revision surgeries. The use of MIS-ATP fusion coupled with PPF could provide a safe and effective strategy against posterior HF. Furthermore, additional benefits of the MIS-ATP technique are inherent to its relatively safe approach-related profile.

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.

Predictive role of FRAX© for postoperative proximal junctional kyphosis with vertebral fracture after adult spinal deformity surgery

PURPOSE

To identify risk factors, including FRAX (a tool for assessing osteoporosis) scores, for development of proximal junctional kyphosis (PJK), defined as Type 2 in the Yagi-Boachie classification (bone failure), with vertebral fracture (VF) after surgery for symptomatic adult spinal deformity.

METHODS

This was a retrospective, single institution study of 127 adults who had undergone corrective long spinal fusion of six or more spinal segments for spinal deformity and been followed up for at least 2 years. The main outcome was postoperative development of PJK with VF. Possible predictors of this outcome studied included age at surgery, BMI, selected radiographic measurements, bone mineral density, and 10-year probability of major osteoporotic fracture (MOF) as determined by FRAX. We also analyzed use of medications for osteoporosis. Associations between the selected variables and PJK with VF were assessed by the Mann-Whitney, Fishers exact, and Wilcoxon signed-rank tests, and Kaplan-Meier analysis, as indicated.

RESULTS

Forty patients (31.5%) developed PJK with VF postoperatively,73% of them within 6 months of surgery. Statistical analysis of the selected variables found that only a preoperative estimate by FRAX of a > 15% risk of MOF within 10 years, pelvic tilt > 30° at first standing postoperatively and lower instrumented level (fusion terminating at the pelvis) were significantly associated with development of PJK with VF.

CONCLUSION

Preoperative assessment of severity of osteoporosis using FRAX provides an accurate estimate of risk of postoperative PJK with VF after surgery for adult spinal deformity.

Distal Junctional Failures in Degenerative Thoracolumbar Hyperkyphosis

OBJECTIVE

Degenerative thoracolumbar hyperkyphosis (DTH) is a disease that negatively affects individual health and requires surgical intervention, yet the ideal surgical approach and complications, especially distal junctional failures (DJF), remain poorly understood. This study aims to investigate DJF in DTH and to identify the risk factors for DJF so that we can improve surgical decision-making, and advance our knowledge in the field of spinal surgery to enhance patient outcomes.

METHODS

This study retrospectively reviewed 78 cases (late osteoporotic vertebral compression fracture [OVCF], 51; Scheuermann's kyphosis [SK], 17; and degenerative disc diseases [DDD], 10) who underwent corrective surgery in our institute from 2008 to 2019. Clinical outcomes were assessed using health-related quality of life (HRQOL) measures, including the visual analogue scale (VAS) scores for back and leg pain, the Oswestry disability index (ODI), and the Japanese Orthopaedic Association (JOA) scoring system. Multiple radiographic parameters, such as global kyphosis (GK) and thoracolumbar kyphosis (TLK), were assessed to determine radiographic outcomes. Multivariate logistic regression analysis was employed to identify the risk factors associated with DJF.

RESULTS

HRQOL improved, and GK, TLK decreased at the final follow-up, with a correction rate of 67.7% and 68.5%, respectively. DJF was found in 13 of 78 cases (16.7%), two cases had wedging in the disc (L3-4) below the instrumentation, one case had a fracture of the lowest instrumented vertebrae (LIV), one case had osteoporotic fracture below the fixation, nine cases had pull-out or loosening of the screws at the LIV and three cases (23.1%) required revision surgery. The DJF group had older age, lower computed tomography Hounsfield unit (CT HU), longer follow-up, more blood loss, greater preoperative sagittal vertical axis (SVA), and poorer postoperative JOA and VAS scores (back). The change in TLK level was larger in the non-DJF group. Post-sagittal stable vertebrae (SSV) moved cranially compared with pre-SSV.

CONCLUSION

Age, CT HU, length of follow-up, estimated blood loss, and preoperative SVA were independent risk factors for DJF. We recommend fixation of the two vertebrae below the apex vertebrae for DTH to minimize surgical trauma.

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

BACKGROUND AND OBJECTIVE

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.

METHODS

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.

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 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).

CONCLUSION

We found that the C-VBQ score was an independent predictive factor of DJK after posterior cervical fusion.

Distal Junctional Failure due to Spondylodiscitis in a Patient with Long Posterior Fixation for Ossified Longitudinal Ligament and Ossified Ligamentum Flavum

Introduction

Distal junctional failure (DJF) is underreported when compared to proximal junctional failure. DJF arising due to spondylodiscitis has never been reported in the literature.

Case Report

A 45-year-old lady with a body mass index of 33 presented with a long-standing inability to walk due to myelopathy secondary to continuous ossified posterior longitudinal ligament and ossified ligamentum flavum. Posterior fusion and laminectomy were done from D2 to L2. She had an initial wound breakdown with a surgical site infection, but after 6 weeks, she developed spondylodiscitis at the distal instrumented vertebra, leading to DJF. She was started on appropriate antibiotics and an extension of fusion.

Conclusion

This report demonstrates and discusses the management of a rare case of DJF arising due to spondylodiscitis of the last instrumented vertebra.

Facet joint disorders: from diagnosis to treatment

One of the most common sources of spinal pain syndromes is the facet joints. Cervical, thoracic, and lumbar facet joint pain syndromes comprise 55%, 42%, and 31% of chronic spinal pain syndromes, respectively. Common facet joint disorders are degenerative disorders, such as osteoarthritis, hypertrophied superior articular process, and facet joint cysts; septic arthritis; systemic and metabolic disorders, such as ankylosing spondylitis or gout; and traumatic dislocations. The facet pain syndrome from osteoarthritis is suspected from a patient's history (referred pain pattern) and physical examination (tenderness). Other facet joint disorders may cause radicular pain if mass effect from a facet joint cyst, hypertrophied superior articular process, or tumors compress the dorsal root ganglion. However, a high degree of morphological change does not always provoke pain. The superiority of innervating nerve block or direct joint injection for diagnosis and treatment is still a controversy. Treatment includes facet joint injection in facet joint osteoarthritis or whiplash injury provoking referred pain or decompression in mass effect in cases of hypertrophied superior articular process or facet joint cyst eliciting radicular pain. In addition, septic arthritis is treated using a proper antibiotic, based on infected tissue or blood culture. This review describes the diagnosis and treatment of common facet joint disorders.

Thoracolumbar/Lumbar Degenerative Kyphosis-The Importance of Thoracolumbar Junction in Sagittal Alignment and Balance

PURPOSE

To conduct a more comprehensive study of sagittal alignment in patients with thoracolumbar/lumbar (TL/L) degenerative kyphosis.

METHODS

A total of 133 consecutive patients from September 2016 to March 2019 with degenerative spinal kyphosis were enrolled. These patients were divided into different types according to sagittal alignment, including thoracolumbar junctional kyphosis (TLJK). Then, we divided the patients with TLJK into two groups: the Sagittal Balance group (C7-SVA < 50 mm) and the Sagittal Imbalance group (C7-SVA ≥ 50 mm). The sagittal parameters of each type or group were compared and correlation analysis was conducted.

RESULTS

Thoracolumbar/lumbar degenerative kyphosis consists of four types: Type I, lumbar kyphosis; Type II, degenerative flat back; Type III, thoracolumbar junctional kyphosis; and Type IV, global kyphosis. According to different sagittal alignments, Type III can further be divided into three subtypes: IIIA, with smooth kyphosis of thoracic and upper lumbar; IIIB, like a clasp knife, with a flat thoracic and lumbar angle; and IIIC, with bigger thoracic kyphosis and lumbar lordosis. The thoracolumbar kyphosis angle (°) of the three subtypes were -23.61 ± 5.37, -25.40 ± 7.71, and -40.01 ± 8.40, respectively. Lumbar lordosis was correlated with thoracic kyphosis (IIIA, r = -0.600, p = 0.005; IIIB, r = -0.312, p = 0.046; IIIC, r = -0.657, p = 0.015), and correlated with sacral slope (IIIA, r = 0.537, p = 0.015; IIIB, r = 0.654, p = 0.000; IIIC, r = 0.578, p = 0.039). All spinopelvic parameters were compared between the Sagittal Balance group and the Sagittal Imbalance group, and only the thoracolumbar kyphosis angle showed statistical difference (t = -2.247, p = 0.028).

CONCLUSIONS

The common characteristics of thoracolumbar junctional kyphosis were found to be a bigger thoracolumbar junctional angle and vertex of kyphosis located in the thoracolumbar junction (T10-L2). Despite TLJK, a change in the thoracic angle was still important to maintain sagittal balance. The thoracolumbar junction plays an important role in sagittal alignment and balance.

Risk Factors for Distal Junctional Problems Following Long Instrumented Fusion for Degenerative Lumbar Scoliosis: Are they Related to the Paraspinal Muscles

PURPOSE

Although the incidence of distal junctional problems (DJPs) following long construct-based treatment for degenerative lumbar scoliosis (DLS) is lower, affected patients are more likely to require revision surgery when they occur. So the aim of this study is to identify risk factors associated with DJPs to avoid its occurrence by at least 1-year follow-up.

METHODS

A total of 182 DLS patients undergoing long instrumented fusion surgery (≥4 levels) between February 2011 and March 2022 were retrospectively analyzed. Patients were placed into the DJP group if a DJP occurred at the final follow-up; patients without mechanical complications were matched 1:2 according to age, sex and BMI as the control group. Patient characteristics, surgical variables, radiographic parameters, lumbar muscularity and fatty degeneration were analyzed statistically. The statistical differences in the results between the two groups (p values <0.05) and other variables selected by experts were entered into a multivariate logistic regression model, and the forwards likelihood ratio method was used to analyze the independent risk factors for DJPs.

RESULTS

Twenty-four (13.2%) patients suffered a DJP in the postoperative period and the reoperation rate was 8.8%. On univariate analysis, the lowest instrumented vertebra (LIV) CT value (p = 0.042); instrumented levels (p = 0.030); preoperative coronal vertical axis (CVA) (p = 0.046), thoracolumbar kyphosis (TLK) (p = 0.006), L4-S1 lordosis (p = 0.013), sacral slop (SS) (p = 0.030), pelvic tilt (PT) classification (p = 0.004), and sagittal vertical axis (SVA) (p = 0.021); TLK correction (p = 0.049); post-operative CVA (p = 0.029); Overall, There was no significant difference in the paraspinal muscle parameters between the two groups. On multivariate analysis, instrumented levels (OR = 1.595; p = 0.035), preoperative SVA (OR = 1.016; p = 0.022) and preoperative PT (OR = 0.873; p = 0.001) were identified as significant independent risk factors for DJP.

CONCLUSION

Longer instrumented levels, a greater preoperative SVA and a smaller PT were found to be strongly associated with the presence of DJPs in patients treated for DLS. The degeneration of the paraspinal muscles may not be related to the occurrence of DJPs. For DLS patients, the occurrence of DJP can be reduced by selecting reasonable fusion segments and evaluating the patient's sagittal balance and spino-pelvic parameters before operation.

The three-dimensional coupling mechanism in scoliosis and its consequences for correction

INTRODUCTION

In idiopathic scoliosis, the anterior spinal column has rotated away from the midline and has become longer through unloading and expansion of the intervertebral discs. Theoretically, extension of the spine in the sagittal plane should provide room for this longer anterior spinal column, allowing it to swing back towards the midline in the coronal and axial plane, thus reducing both the Cobb angle and the apical vertebral rotation.

METHODS

In this prospective experimental study, ten patients with primary thoracic adolescent idiopathic scoliosis (AIS) underwent MRI (BoneMRI and cVISTA sequences) in supine as well as in an extended position by placing a broad bolster, supporting both hemi-thoraces, under the scoliotic apex. Differences in T4-T12 kyphosis angle, coronal Cobb angle, vertebral rotation, as well as shape of the intervertebral disc and shape and position of the nucleus pulposus, were analysed and compared between the two positions.

RESULTS

Extension reduced T4-T12 thoracic kyphosis by 10° (p < 0.001), the coronal Cobb angle decreased by 9° (p < 0.001) and vertebral rotation by 4° (p = 0.036). The coronal wedge shape of the disc significantly normalized and the wedged and lateralized nucleus pulposus partially reduced to a more symmetrical position.

CONCLUSION

Simple extension of the scoliotic spine leads to a reduction of the deformity in the coronal and axial plane. The shape of the disc normalizes and the eccentric nucleus pulposus partially moves back to the midline.

Pathophysiology of cervical myelopathy (Review)

Cervical myelopathy is a well-described medulla spinalis syndrome characterized by sensory disorders, such as pain, numbness, or paresthesia in the limbs, and motor disorders, such as muscle weakness, gait difficulties, spasticity, or hyperreflexia. If left untreated, cervical myelopathy can significantly affect the quality of life of patients, while in severe cases, it can cause disability or even quadriplegia. Cervical myelopathy is the final stage of spinal cord insult and can result from transgene dysplasias of the spinal cord, and acute or chronic injuries. Spondylosis is a common, multifactor cause of cervical myelopathy and affects various elements of the spine. The development of spondylotic changes in the spine is gradual during the patient's life and the symptoms are presented at a late stage, when significant damage has already been inflicted on the spinal cord. Spondylosis is widely considered a condition affecting the middle aged and elderly. Given the fact that the population is gradually becoming older, in the near future, clinicians may have to face an increased number of patients with spondylotic myelopathy.

Prevention of Proximal Junctional Kyphosis Using Proximal Fixation Techniques

BACKGROUND

Adult spinal deformity (ASD) is a disorder characterized by abnormal curvature of the spine resulting from progressive degeneration of spinal elements. Although operative intervention for ASD is commonplace, it is associated with several complications, including proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). The objective of this review is to outline the role of proximal fixation in preventing PJK and PJF.

METHODS

We conducted a literature search using the Embase, Scopus, Web of Science, CINHAL, Cochrane Library, and PubMed MEDLINE databases. We considered only studies focusing on adult patients and selected clinical studies investigating proximal fixation techniques.

RESULTS

There was mixed evidence of the efficacy of hooks and other instrumentation methods in preventing PJK, although most studies supported the use of hooks. Selection of lower thoracic vertebrae was associated with higher rates of PJK and PJF in several studies, although the relationship was inconsistent, and many studies reported no significant difference in rates of PJK or PJF between different upper instrumented vertebra (UIV) levels. Other techniques that are not related to specific instrumentation or vertebral selection, such as adjusting UIV screw trajectory, were also referenced. However, the evidence supporting these techniques was limited.

DISCUSSION

Despite the presence of numerous studies in the literature discussing proximal fixation strategies to reduce the incidence of PJK/PJF, the lack of prospective studies and high variability in study methods make direct comparison challenging. We could not draw strong conclusions regarding the superiority of any one technique, despite promising clinical results with a strong biomechanical basis in several studies.

CLINICAL RELEVANCE

This systematic literature review showed that a variety of proximal fixation techniques have been used to prevent PJK/PJF without clear evidence in favor of any particular technique.

LEVEL OF EVIDENCE: 3

Hemivertebra resection after age three produces the similar results but with less complications compared to earlier surgery: a minimum of 5-year follow-up

BACKGROUND

The optimal timing for hemivertebra resection remains controversial. Early intervention before 3 years of age seems being able to get better correction with less fusion segments. However, it was also reported that early surgery may be associated with more complications. The purpose of this study is to investigate correction outcomes and complications of delayed hemivertebra resection (between 3 and 5 years of age), in comparison with earlier surgery (before 3 years of age).

METHODS

Patients who had undergone thoracolumbar hemivertebra resection at a single level before 5 years of age and had more than 5 years of follow-up were reviewed. Twenty-four patients had hemivertebra resection surgery below 3 years of age (early surgery, Group E), and 33 patients received surgery between 3 and 5 years of age (delayed surgery, Group D). Radiographs from preoperative, immediately postoperative, and the latest follow-up visits were reviewed to investigate the correction outcomes. Complications were recorded and compared between these two groups.

RESULTS

The patients of Group E had shorter operation time and less blood loss than those of Group D (P = 0.003 and P = 0.006). Notably, the fusion segments were 2.3 ± 0.7 and 3.1 ± 1.2 in group E and group D (P = 0.005), respectively, indicating group E averagely saved 0.8 motion segments. At the time of surgery, group E had smaller main curve magnitude either in the coronal or in the sagittal plane than group D and experienced similar correction rates of scoliosis (83.3 ± 21.6% vs. 81.2 ± 20.1%, P = 0.707) and kyphosis (65.1 ± 23.8% vs. 71.7 ± 24.9%, P = 0.319). However, group E had relatively higher complication rates than group D and relatively greater correction loss in either coronal or sagittal plane during follow-up.

CONCLUSIONS

Hemivertebra resection resulted in similar correction results in both age groups. However, the rate of complications was lower for Group D than Group E. Thus, for non-kyphotic hemivertebra, surgery may be delayed till 3 to 5 years of age.

Percutaneous Vertebroplasty and Upper Instrumented Vertebra Cement Augmentation Reducing Early Proximal Junctional Kyphosis and Failure Rate in Adult Spinal Deformity: Case Series and Literature Review

BACKGROUND AND OBJECTIVES

One of the risks involved after long-segment fusions includes proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). There are reported modalities to help prevent this, including 2-level prophylactic vertebroplasty. In this study, our goal was to report the largest series of prophylactic cement augmentation with upper instrumented vertebra (UIV) + 1 vertebroplasty and a literature review.

METHODS

We retrospectively reviewed our long-segment fusions for adult spinal deformity from 2018 to 2022. The primary outcome measures included the incidence of PJK and PJF. Secondary outcomes included preoperative and postoperative Oswestry Disability Index, visual analog scale back and leg scores, surgical site infection, and plastic surgery closure assistance. In addition, we performed a literature review searching PubMed with a combination of the following words: "cement augmentation," "UIV + 1 vertebroplasty," "adjacent segment disease," and "prophylactic vertebroplasty." We found a total of 8 articles including 4 retrospective reviews, 2 prospective reviews, and 2 systematic reviews. The largest cohort of these articles included 39 patients with a PJK/PJF incidence of 28%/5%.

RESULTS

Overall, we found 72 long-segment thoracolumbar fusion cases with prophylactic UIV cement augmentation with UIV + 1 vertebroplasty. The mean follow-up time was 17.25 months. Of these cases, 8 (11.1%) developed radiographic PJK and 3 (4.2%) required reoperation for PJF. Of the remaining 5 patients with radiographic PJK, 3 were clinically asymptomatic and treated conservatively and 2 had distal fractured rods that required only rod replacement.

CONCLUSION

In this study, we report the largest series of patients with prophylactic percutaneous vertebroplasty and UIV cement augmentation with a low PJK and PJF incidence of 11.1% and 4.2%, respectively, compared with previously reported literature. Surgeons who regularly perform long-segment fusions for adult spinal deformity can consider this in their armamentarium when using methods to prevent adjacent segment disease because it is an effective modality in reducing early PJK and PJF that can often result in revision surgery.

Junctional Kyphosis after Correction with Long Instrumentation for Late Posttraumatic Thoracolumbar Kyphosis: Characteristics and Risk Factors

OBJECTIVE

Junctional kyphosis is a common complication after corrective long spinal fusion for adult spinal deformity. Whereas there is still a paucity of data on junctional kyphosis, specifically among late posttraumatic thoracolumbar kyphosis (LPTK) patients. Thus, the aim of this study was to investigate the characteristics and risk factors of junctional kyphosis in LPTK patients receiving long segmental instrumented fusion.

METHODS

We retrospectively reviewed a cohort of LPTK patients who had received long segmental instrumented fusion (>4 segments) in our center between January 2012 and January 2019. Radiographic assessments included the sagittal alignment, pelvic parameters, bone quality on CT images, and measurements of the cross-sectional area (CSA, cross-sectional area of muscle-vertebral body ratio × 100) and fat saturation fraction (FSF, cross-sectional area of fat-muscle body ratio × 100) of paraspinal muscles. Patients in this study were divided into those with junctional kyphosis or failure (Group J) and those without (Group NJ) during follow-up. Group J included patients with junctional kyphosis (Group JK) and patients with junctional failure (Group JF).

RESULTS

A total of 65 patients (16 males and 49 females, average age 56.5 ± 23.4 years) were enrolled in this study. After (32.7 ± 8.5) months follow-up, 15 patients (23.1%) experienced junctional kyphosis, and four of them deteriorated into junctional failure. Eighty percent (12/15) of junctional kyphosis was identified within 6 months after surgery. In comparison with Group NJ, Group J were older (P = 0.026), longer fusion levels (P < 0.001), greater thoracic kyphosis (P = 0.01), greater global kyphosis (P = 0.023), lower bone quality (P < 0.001), less CSA (P = 0.005) and higher FSF (P <0.001) of paraspinal muscles. Preoperative global kyphosis more than 48.5° (P = 0.001, odds ratio 1.793) and FSF more than 48.4 (P = 0.010, odds ratio 2.916) were identified as independent risk factors of junctional kyphosis. Based on the statistical differences among Group NJ, Group JK and Group JF (P < 0.001), Group JF had lower bone quality than Group NJ (P < 0.001) and Group JK (P = 0.015). In terms of patient-reported outcomes, patients in Group JF had worse outcomes in ODI and VAS scores, and PCS and MCS of SF-36 than Group NJ and group JK CONCLUSION: The prevalence of junctional kyphosis was 23.1% in LPTK patients after long segmental instrumented fusion. Preoperative hyperkyphosis and advanced fatty degeneration of paraspinal muscles were independent risk factors of junctional kyphosis. Patients with lower bone quality were more likely to develop junctional failure.

Selecting proper distal fusion level in severe thoracolumbar kyphosis secondary to late osteoporotic vertebral compression fracture to limit distal complications

BACKGROUND

Surgical treatment of severe thoracolumbar kyphosis (TLK) secondary to late osteoporotic vertebral compression fracture (OVCF) presents several challenges to spine surgeons. Proper selection of distal fusion level is an important issue in surgical planning to decrease the likelihood of distal mechanical complications. This study was designed to compare the clinical and radiographic outcomes in elderly patients suffering from severe TLK related with late OVCF between different distal fusion strategies and to recommend a superior distal fusion level for these patients.

METHODS

A total of 57 consecutive subjects with a minimum follow-up of two years were retrospectively reviewed. TLK was defined as the hyperkyphosis with an apex below T10. Severe TLK was defined as the Cobb angle of kyphosis ≥60°. Patients fused to sagittal stable vertebra (SSV) were assigned to Group SSV, while those fused to the vertebra above and below SSV were assigned to Groups SSV- and SSV+, respectively. Bone cement was used to enhance pedicle screw fixation. Clinical and radiographic results were collected and compared between different groups.

RESULTS

Deformity corrections and living quality improvements at the latest follow-up were superior in Group SSV than Group SSV- with shorter fusion levels, while to the equal extent with Group SSV+ with longer fusion levels. 7 cases of distal complications were observed in Group SSV-. Negatively balanced lowest instrumented vertebra was revealed to be the independent factor predicting distal complications. Patients' satisfaction of their surgical management was greater in Group SSV than Group SSV- (83.2 ± 4.4% vs. 70.5 ± 10.9%, P = 0.024), while comparable with Groups SSV + SSV+ (84.8 ± 5.7%).

CONCLUSIONS

Fusion to SSV with cement-augmented pedicle screws could limit the development of distal junctional mechanical complications after surgical treatment for severe TLK secondary to late OVCF in elderly patients, while achieves satisfactory deformity correction with the preservation of necessary lumbar motility.

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

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

Instrumentation Techniques to Prevent Proximal Junctional Kyphosis and Proximal Junctional Failure in Adult Spinal Deformity Correction: A Systematic Review of Clinical Studies

STUDY DESIGN

Systematic review.

OBJECTIVES

To summarize the results of clinical studies investigating spinal instrumentation techniques aiming to reduce the postoperative incidence of proximal junctional kyphosis (PJK) and/or failure (PJF) in adult spinal deformity (ASD) patients.

METHODS

EMBASE and Medline® were searched for articles dating from January 2000 onward. Data was extracted by 2 independent authors and methodological quality was assessed using ROBINS-I.

RESULTS

18 retrospective- and prospective cohort studies with a severe or critical risk of bias were included. Different techniques were applied at the upper instrumented vertebra (UIV): tethers in various configurations, 2-level prophylactic vertebroplasty (2-PVP), transverse process hooks (TPH), flexible rods (FR), sublaminar tapes (ST) and multilevel stabilization screws (MLSS). Compared to a pedicle screw (PS) group, significant differences in PJK incidence were found using tethers in various configurations (18% versus 45%, P = 0.001, 15% versus 38%, P = 0.045), 2-PVP (24% vs 36%, P = 0.020), TPH (0% vs. 30%, P = 0.023) and FR (15% versus 38%, P = 0.045). Differences in revision rates for PJK were found in studies concerning tethers (4% versus 18%, P = 0.002), 2-PVP (0% vs 13%, P = 0.031) and TPH (0% vs 7%, P = n.a.).

CONCLUSION

Although the studies are of low quality, the most frequently studied techniques, namely 2-PVP as anterior reinforcement and (tensioned) tethers or TPH as posterior semi-rigid fixation, show promising results. To provide a reliable comparison, more controlled studies need to be performed, including the use of clinical outcome measures and a uniform definition of PJF.

Risk factors for L5 pedicle fractures after single-level posterior spinal fusion

BACKGROUND CONTEXT

Pedicle fractures are a rare but potentially devastating complication of posterior instrumented spinal fusion (PSF). Preoperative awareness of the possible risk factors may help prevent these fractures by modifying the surgical plan. However, the risk factors have not yet been identified.

PURPOSE

To determine the preoperative parameters associated with postoperative L5 pedicle fracture after L4/5 PSF.

STUDY DESIGN

Case control study.

PATIENT SAMPLE

Patients undergoing L4/5 PSF at a single academic institution between 2014 and 2020.

OUTCOME MEASURES

Occurrence of postoperative L5 pedicle fracture.

METHODS

Of 253 patients (female:male, 145:108) undergoing L4/5 PSF from 2014 to 2020, patients with postoperative L5 pedicle fractures were identified retrospectively as "cases" (n = 8, all female, age: 70 ± 10.7 years). As a control group all remaining patients with a follow-up of more than 12 months were allocated (n = 184, 104 females, age: 64.27 ± 13.00 years). In all but 16 cases, anterior support with transforaminal or posterior interbody fusion was performed. Demographic and clinical data (body mass index (BMI)), surgical factors, and comorbidities) were compared. Radiological assessment of spinopelvic parameters was performed using pre- and postoperative standing lateral radiographs.

RESULTS

The overall incidence of L5 pedicle fractures after L4/5 spinal fusion was 3.16%, with a median time from index surgery to diagnosis of 25 days (range, 6-199 days) (75% within the first 32 days postoperatively). Patients with L5 pedicle fractures had higher pelvic incidence (PI) (71° ± 9° vs. 56° ± 11°; p=.001), sacral slope (SS) (45° ± 7° vs. 35° ± 8°; p=.002), L5 slope (30° ± 11° vs. 15° ± 10°, p=.001), L5 incidence (42° ± 14° vs. 26° ± 11°; p= .003), L1-S1 lumbar lordosis (LL) postop (57° ± 10° vs. 45° ± 11°; p=.006), and L4 -S1 LL postop (33° ± 7° vs. 28° ± 7°; p=.049) compared with the control group. Pelvic tilt and PI- LL mismatch were not significantly different. Female gender was a significant risk factor for L5 pedicle fractures (p=.015). BMI (kg/m²) was statistically equal in patients with or without pedicle fractures (28.37 ± 5.96 vs. 28.53 ± 16.32; p=.857). There was no significant difference between the groups for approximative bone mineral density assessment (Hounsfield units; 113 ± 60 vs. 120 ± 43; p=.396) using the L3 trabecular region of interest (ROI) measurement. The correlation analysis demonstrated that most of the identified risk factors except for the postoperative L4-S1 lordosis show significant positive associations among each other. All eight patients in the fracture group underwent revision surgery, and the instrumented fusion was extended to the sacrum, with the addition of sacral-alar-iliac or iliac screws, in six cases.

CONCLUSIONS

L5 pedicle fractures occurred in 3% of the patients after single level L4/5 PSF. Risk factors are female gender, higher PI, SS, L5 slope, L5 incidence, and LL postop but not high BMI. These findings can be used for surgical planning and decision of fusion levels.

Minimally invasive surgery using posterior-only Pedicle screw fixation in treatment of Adolescent Idiopathic Scoliosis: A Systematic Review and Meta-Analysis

Minimally invasive surgery (MIS) techniques for posterior spine pedicle-screw fusion (PSF) may reduce the AIS surgery invasiveness, although they require a certain degree of patient selection based on the severity of the curve. The aim of this article is to systematically review the Literature to determine efficacy and safety of MIS-PSF in AIS correction, and to compare its outcomes with open-PSF. A systematic search of electronic databases from eligible articles was conducted. Only studies adopting MIS-PSF for AIS were included. Clinical and radiographic outcomes were extracted and summarized. Meta-analyses were performed. P-value < 0.05 was considered significant. Thirteen studies for a total of 635 patients ungergoing MIS-PSF were included in this review. Pre-operative Cobb's angle ranged from 48.3°±4.2° to 59.8°±6.6°, coronal correction from 58.1% to 79.1%, average operative time ranged from 252 to 526.8 min, average estimated blood loss from 138.8 ± 50 to 1250 mL. Sixty-seven complications were recorded (9.9%), with 19 revisions (3.8%), resulting similar to those described in Literature using open-PSF. At meta-analysis, MIS-PSF (321 patients) compared to open-PSF (429 patients) showed lower coronal correction (although no statistically significant difference was found), estimated blood loss and length of hospital stay, but higher operative time. No differences in SRS-22, complications and revision rate were found. In conclusion, open-PSF shows a trend towards higher correction in the coronal plane and requires a shorter operative time when compared to MIS-PSF. It remains the gold standard for AIS correction, although MIS-PSF seems to be a viable and promising technique for selected patients. - KEYWORDS: minimally invasive surgery, minimally invasive techniques, adolescent idiopathic scoliosis, posterior spinal fusion, pedicle-screws-only instrumentation.

Risk factors for postoperative coronal decompensation in adult lumbar scoliosis after posterior correction with osteotomy

INTRODUCTION

To determine potential risk factors for postoperative coronal imbalance following posterior osteotomy for adult scoliosis.

MATERIALS AND METHODS

A total of 74 patients underwent osteotomy for rigid adult lumbar scoliosis. A group of 20 patients with postoperative coronal imbalance was identified. Clinical data and surgical strategies were compared to determine the risk factors, including age, gender, etiology, Cobb angle, preoperative coronal balance distance, direction of preoperative imbalance, T1 tilt, tilt of upper instrumented vertebra (UIV), UIV translation, location of UIV (T6 above or below), fusion to L5 or S1, lower instrumented vertebra (LIV) tilt, LIV rotation, screw density, osteotomy procedure (PSO or SPOs) and use of iliac screws.

RESULTS

Comparison between patients with and without postoperative coronal imbalance showed that postoperative coronal imbalance occurred in older patients and those with degenerative scoliosis as the etiology, UIV above T6, preoperative LIV rotation, preoperative LIV tilt and preoperative coronal imbalance towards the convex side and who underwent Smith-Petersen osteotomy. All seven parameters were included in the logistic regression analysis. UIV above T6 (P = 0.010), LIV rotation (P = 0.012) and preoperative coronal imbalance towards the convex side (P = 0.005) were identified as risk factors for postoperative coronal imbalance after osteotomy.

CONCLUSIONS

Patients with preoperative coronal imbalance towards the convex side (UIV above T6) and LIV rotation were more likely to develop coronal imbalance than those without risk factors. Older patients and those with degenerative scoliosis were also at a relatively higher risk of postoperative coronal imbalance.

Validity of the Roussouly classification system for assessing distal junctional problems after long instrumented spinal fusion in degenerative scoliosis

PURPOSE

To evaluate the validity of the Roussouly classification system for assessing distal junctional problems (DJP) after long instrumented spinal fusion in degenerative scoliosis.

METHODS

Sixty-four patients with degenerative scoliosis and long-segment fixation receiving treatment at our hospital between December 2012 and December 2018 were retrospectively analyzed. Patients were classified preoperatively and postoperatively (Roussouly classification) and divided into DJP and control groups. We observed whether patients restored to their preoperative Roussouly classification (based on pelvic incidence [PI]) postoperatively.

RESULTS

The incidences of DJP were 11.11% and 50% in patients who did and did not match their sagittal Roussouly classification immediately postoperatively, respectively. The adjusted Chi-square test that showed whether the sagittal profile matched the Roussouly classification immediately after surgery was statistically significant (P = 0.012). PIs were 55.83 ± 4.94 and 47.21 ± 10.81 in the DJP and non-DJP groups, respectively (t' = 4.367, P < 0.001). Distal junctional kyphosis angles were 6.33 ± 4.19° and 11.56 ± 5.02° in the DJP and non-DJP groups, respectively (t = - 2.595, P = 0.015). Preoperative PI-lumbar lordosis values were 29.14 ± 13.82 and 16.67 ± 11.39 in the DJP and non-DJP groups, respectively (t = - 2.626, P = 0.013). The logistic regression model showed that patients whose Roussouly classification did not match the postoperative PI value were more likely to have DJP (odds ratio [OR] = 4.01, 95% confidence interval [CI]: 0.51-31.61) and preoperative distal junctional kyphotic changes.

CONCLUSION

If the postoperative sagittal profile can be restored to match the patient's own PI value, use of the Roussouly classification can greatly reduce the possibility of postoperative DJP.

Understanding "Kyphosis" and "Lordosis" for Sagittal Balancing in Two Common Standing Postures

STUDY DESIGN

Cross-sectional radiographic comparison study.

OBJECTIVE

The aim of this study was to understand whole-body balancing in directed and natural standing postures, through comparison of kypholordotic ratios on whole-body radiographs of young, healthy subjects.

SUMMARY OF BACKGROUND DATA

Recent studies highlighted the importance of understanding whole-body balancing, proposing the use of the more physiological natural standing posture, together with the conventional directed standing posture, for imaging.

METHODS

Sixty healthy, 21-year-old subjects (36 males, 24 females) were recruited. EOS whole-body radiographs of subjects in directed and natural standing postures were obtained. Radiographic parameters compared include C2-sagittal vertical axis (C2-SVA), C7-SVA, C2-7-SVA, global cervical angles (C0-T1 and C2-C7), regional cervical angles (C0-C2, C2-C4, C4-C7), T1-slope, global thoracic angles (T1-T12 and T1-inflection vertebra [Inf]), thoracolumbar angle (T11-L2), global lumbar angles (T12-S1 and Inf-S1), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), spinocoxa angle (SCA), and femoral alignment angle (FAA). Kypholordotic ratios of T1-12/T12-S1, T1-Inf/Inf-S1, Tl-Inf/SCA, and (T1-Inf + FAA)/(T1-slope + SCA) were calculated and compared.

RESULTS

Compared to directed standing, natural standing has greater C2-SVA and C7-SVA, more lordotic global and regional cervical angles (except C0-2 angle), higher T1-slope, larger T1- T12 and T1-Inf kyphotic angles, smaller T12-S1 and Inf-S1 lordotic angles, larger PT, more lordotic SCA, and smaller SS and FAA angles. T1-12/T12-S1 and T1-Inf/Inf-S1 ratios in natural standing, and (Tl-Inf + FAA)/(T1-slope + SCA) ratio in both postures approximate 1. There were significant differences between postures for Tl-l2/Tl2-Sl, Tl-Inf/Inf-Sl and Tl-Inf/SCA ratios.

CONCLUSION

Whole-body balancing requires understanding of the balance between kyphosis and lordosis, which varies with the posture of patients. Analysis of kypholordotic ratios obtained in this study allude to the importance of performing whole-body imaging in the directed standing posture, and whole-spine or whole-body imaging in the natural standing posture, so as to fully understand spinal and whole body balancing for spinal realignment surgeries.Level of Evidence: Level 3.

Reduced proximal junctional failure with ligament augmentation in adult spinal deformity: a series of 242 cases with a minimum 1-year follow-up

OBJECTIVE

Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are well-recognized complications of long-segment spinal fusion. Previous studies have suggested that ligament augmentation can decrease rates of PJF by reducing junctional stress and strengthening upper instrumented vertebrae (UIVs) and adjacent segments. However, there is a paucity of long-term data on the efficacy of ligament augmentation in preventing PJF. In this study, the authors sought to determine the effect of ligament augmentation on rates of PJF in a cohort of adult spinal deformity patients with at least 1 year of follow-up.

METHODS

They conducted a retrospective analysis of ligament augmentation in a consecutive series of surgical patients with adult spinal deformity. Data on patient demographics, surgical characteristics, and surgery for PJF were collected. The minimum follow-up was 12 months. Univariate and multivariate analyses were performed to identify factors associated with reoperation for PJF.

RESULTS

The authors identified a total of 242 patients (166 women [68.6%]) with ligament augmentation whose mean age was 66 years. The mean number of fused levels was 10, with a UIV distribution as follows: 90 upper thoracic UIVs (37.2%) and 152 lower thoracic UIVs (62.8%). Compared to a historical cohort of 77 patients treated before implementation of ligament augmentation, reoperation for PJF was significantly lower with ligament augmentation (15.6% vs 3.3%, p < 0.001). In a multivariate model, only ligament augmentation (OR 0.184, 95% CI 0.071-0.478, p = 0.001) and number of fused levels (OR 0.762, 95% CI 0.620-0.937, p = 0.010) were associated with reductions in reoperation for PJF.

CONCLUSIONS

Ligament augmentation was associated with significant reductions in the rate of reoperation for PJF at 12 months in a cohort of adult spinal deformity patients. The most dramatic reduction was seen among patients with lower thoracic UIV. These data suggest that in appropriately selected patients, ligament augmentation may be a valuable adjunct for PJF reduction; however, long-term follow-up is needed.

The impact of the lower instrumented level on outcomes in cervical deformity surgery

Background:

The lower instrumented vertebrae (LIVs) in cervical deformity (CD) constructs may have varying effects on patient outcomes that are still poorly understood.

Objective:

The objective of the study is to compare outcomes in CD patients undergoing instrumented correction according to the relation of LIV with primary driver (PD).

Methods:

Patients who met radiographic criteria for CD were included in the study. Patients were stratified by PD of deformity: cervical (C) through AMES classification (TS-CL >20 or cervical sagittal vertical axis >40) and thoracic (T) through hyper/hypokyphosis (TK) from T4-T12 (60 < TK < 40). Patients were further stratified by LIV in relation to curve apex (above/below). Univariate and multivariate analyses identified group differences in postoperative health-related quality-of-life and distal junctional kyphosis (DJK) (>10° LIV and LIV + 2) rate up to 1 year.

Results:

Sixty-two patients were analyzed. Twenty-one patients had a C-PD and 41 had a T-PD by definition. 100% of C-PDs had LIVs below CL apex, while 9.2% of T-PDs had LIVs below (caudal) to TK apex and 90.8% had LIVs above TK apex. By 1 year, C patients trended lower Neck Disability Index (NDI) (21.9 vs. 29.0, P = 0.245), lower numeric rating scales neck pain (4.2 vs. 5.1, P = 0.358), and significantly higher EuroQol five-dimensional questionnaire Visual Analog Scale (69.2 vs. 52.4, P = 0.040). When T patients with LIVs below TK apex were excluded, remaining T patients with LIV above apex had significantly higher 1-year NDI than C patients (37.5 vs. 21.9, P = .05). T patients also trended higher rates of postoperative DJK than C (19.5% vs. 4.8%, P = 0.119).

Conclusions:

Stopping before apex was more common in patients with a primary thoracic driver (T) and associated with deleterious effects. Primary cervical driver (C) tended to have LIVs inclusive of CL apex with lower rates of DJK.

Failure patterns and related risk factors of sagittal reconstruction following pedicle subtraction osteotomy in patients with ankylosing spondylitis and thoracolumbar kyphosis

OBJECTIVE

The aim of this study was to analyze the specific patterns and risk factors of sagittal reconstruction failure in ankylosing spondylitis (AS)-related thoracolumbar kyphosis after pedicle subtraction osteotomy (PSO).

METHODS

A retrospective study was performed in patients with AS and thoracolumbar kyphosis after lumbar PSO with a minimum follow-up of 2 years. Patients were classified as having successful realignment (group A), inadequate correction immediately postoperatively (group B), and sagittal decompensation during follow-up (group C) according to the immediately postoperative and latest follow-up sagittal vertical axis (SVA). Radiographic parameters and clinical outcomes were collected. Pelvic tilt (PT) was used to assess the magnitude of pelvic backward rotation. Hip structural damage and ossification of the anterior longitudinal ligament (ALL) at the proximal junction, PSO level, and distal junction were also evaluated on radiographs.

RESULTS

Overall, 109 patients with a mean age of 35.3 years were included. Patients in both group B (n = 16) and group C (n = 13) were older than those in group A (n = 80) (mean ages 43.6 vs 32.9 years, p < 0.011; and 39.2 vs 32.9 years, p = 0.018; respectively). Age (OR 1.102, p = 0.011), and preoperative PT (OR 1.171, p = 0.041) and SVA (OR 1.041, p = 0.016) were identified as independent risk factors of inadequate correction. Additionally, a higher distribution of patients with adequate ALL ossification at the PSO level was found in group B than in group A (37.5% vs 22.5%, p = 0.003). Age (OR 1.101, p = 0.011) and preoperative SVA (OR 1.013, p = 0.020) were identified as independent risk factors of sagittal decompensation. Furthermore, compared with group A, group C showed a higher distribution of patients with severe hip structural damage (15.4% vs 0, p = 0.018) and higher incidences of rod fracture (RF) (38.5% vs 8.8%, p = 0.011) and pseudarthrosis (15.4% vs 0, p = 0.018). Additionally, the incidence of RF (19.6% vs 6.9%, p = 0.045) and changes in the proximal junctional angle (0.5° vs 2.2°, p = 0.027) and the distal junctional angle (0.3° vs 2.2°, p = 0.019) were lower during follow-up in patients with adequate ALL ossification than in those without adequate ossification.

CONCLUSIONS

Sagittal reconstruction failure in patients with AS could be attributed to inadequate correction immediately after surgery (14.7%) and sagittal decompensation during follow-up (11.9%). Adequate ALL ossification was a risk factor of inadequate correction. However, adequate ALL ossification could decrease the development of RF and relieve the junctional kyphotic change during follow-up. Older age and greater baseline SVA were independent risk factors for both inadequate correction and sagittal decompensation.

Surgical outcomes for late neurological deficits after long segment instrumentation for degenerative adult spinal deformity

OBJECTIVE

The most catastrophic symptom of proximal junctional failure (PJF) following long instrumented fusion surgery for adult spinal deformity (ASD) is neurological deficits. Although previous reports have shown that PJF usually developed during the early postoperative period, some patients showed late neurological deficits. The aim of this study was to report the incidence, characteristics, and surgical outcomes of PJF with late neurological deficits.

METHODS

Patients surgically treated for ASD at a single institution were retrospectively reviewed. Among them, the patients requiring revision surgery for newly developed neurological deficits at least 6 months after the initial surgery were included. Patient demographic, radiographic, surgical, and clinical data were investigated. Neurological status was assessed using the Frankel grading system.

RESULTS

PJF with late neurological deficits developed in 18 of 385 patients (4.7%). The mean age at the onset of neurological deficits was 72.0 ± 6.0 years, and the median time from the initial surgery was 4.5 years. The most common pathology of PJF was adjacent disc degeneration and subsequent canal stenosis (11 patients). Five patients showed disc degeneration with aseptic bone destruction. Fractures at the upper instrumented vertebra (UIV), UIV + 1, and UIV + 2 occurred in 2, 3, and 2 patients, respectively. Ossification of the yellow ligament, which had not been found at the first surgery, was identified in 6 patients. Eight patients showed improvement of their neurological deficits and 10 patients showed no improvement by the final follow-up. Perioperative major complications occurred in 8 of 18 patients.

CONCLUSIONS

The incidence of PJF with late neurological deficits following ASD surgery was 4.7% in this cohort. The patients showed several morphological features. After revision surgery, perioperative complications were common and the prognosis for improved neurological status was not favorable.

A Systematic Review of Treatment Strategies for the Prevention of Junctional Complications After Long-Segment Fusions in the Osteoporotic Spine

STUDY DESIGN

Systematic review.

OBJECTIVES

Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are well-known complications after long-segment fusions in the thoracolumbar spine of osteoporotic patients. Recent advances in anti-resorptive and anabolic medications, instrumentation, surgical technique, and cement augmentation have all aided in the avoidance of junctional kyphosis. In this article, current literature on the prevention of PJK and PJF in the osteoporotic spine is reviewed.

METHODS

A systematic literature review was conducted using the PubMed/MEDLINE and Embase databases in order to search for the current preventive treatment methods for PJK and PJF published in the literature (1985 to present). Inclusion criteria included (1) published in English, (2) at least 1-year mean and median follow-up, (3) preoperative diagnosis of osteoporosis, (4) at least 3 levels instrumented, and (5) studies of medical treatment or surgical techniques for prevention of junctional kyphosis.

RESULTS

The review of the literature yielded 7 studies with low levels of evidence ranging from level II to IV. Treatment strategies reviewed addressed prophylaxis against ligamentous failure, adjacent vertebral compression fracture, and/or bone-implant interface failure. This includes studies on the effect of osteoporosis medication, cement augmentation, multi-rod constructs, and posterior-tension band supplementation. The role of perioperative teriparatide therapy maintains the highest level of evidence.

CONCLUSIONS

Perioperative teriparatide therapy represents the strongest evidence for preventive treatment, and further clinical trials are warranted. Use of cement augmentation, sublaminar tethers, and multi-rod constructs have low or insufficient evidence for recommendations. Future guidelines for adult spinal deformity correction may consider bone mineral density-adjusted alignment goals.

Biomechanical Evaluation of a Dynamic Stabilization System for the Prevention of Proximal Junctional Failure in Adult Deformity Surgery

STUDY DESIGN

Biomechanical spine model. Comparison of stress in the implant and the adjacent cranial segment was done with conventional rigid versus dynamic stabilization system (DS) fixation.

OBJECTIVE

The aim of this study was to study stress at the proximal end of spinal fixation with a novel DS.

SUMMARY OF BACKGROUND DATA

High stress at the implant bone junction may cause proximal junctional failure (PJF) in adult deformity surgery.

METHODS

Five life-size spine models were instrumented with pedicle screws and a 5.5-mm Titanium rod from T8-S1. The same models were subsequently instrumented with a similar rod and DS between T8-9 pedicle screws. The spine model was loaded with 25 Nm static load cranial to the proximal fixation in six directions. Strains were measured from the proximal screws. Disc pressure was measured from the proximal instrumented segment (T8-9) and cranial adjacent segment (T7-8).

RESULTS

Rigid fixation produced highest strain at T8, followed by T10 then T9. In contrast, DS fixation produced highest strain at T10, followed by T9 then T8. Strain at T8 was significantly less with DS fixation than rigid fixation (P = 0.019). The T10 screw strain was not significantly higher with DS stabilization compared to rigid fixation (P = 0.091). Rigid fixation allowed no load-sharing or pressure rise at T8-9 but an abrupt rise at T7-8. DS system permitted load-sharing and pressure rise in T8-9; the difference compared to rigid fixation was significant in flexion loading (P = 0.04) and similar trend but not significant in extension (P = 0.09). DS system produced a rise in the adjacent segment disc pressure (T7-8), which was smaller than rigid fixation but not significant.

CONCLUSION

Long spinal fixation using rigid rods produces maximum stress at the proximal end screw and increases adjacent disc pressure, possibly leading to PJF. Dynamic stabilization at the cranial end segment may prevent PJF by reducing these factors.Level of Evidence: N/A.

Effect of age-adjusted alignment goals and distal inclination angle on the fate of distal junctional kyphosis in cervical deformity surgery

Background:

Age-adjusted alignment targets in the context of distal junctional kyphosis (DJK) development have yet to be investigated. Our aim was to assess age-adjusted alignment targets, reciprocal changes, and role of lowest instrumented level orientation in DJK development in cervical deformity (CD) patients.

Methods:

CD patients were evaluated based on lowest fused level: cervical (C7 or above), upper thoracic (UT: T1–T6), and lower thoracic (LT: T7–T12). Age-adjusted alignment targets were calculated using published formulas for sagittal vertical axis (SVA), pelvic incidence-lumbar lordosis (PI-LL), pelvic tilt (PT), T1 pelvic angle (TPA), and LL-thoracic kyphosis (TK). Outcome measures were cervical and global alignment parameters: Cervical SVA (cSVA), cervical lordosis, C2 slope, C2–T3 angle, C2–T3 SVA, TS-CL, PI-LL, PT, and SVA. Subanalysis matched baseline PI to assess age-adjusted alignment between DJK and non-DJK.

Results:

Seventy-six CD patients included. By 1Y, 20 patients developed DJK. Non-DJK patients had 27% cervical lowest instrumented vertebra (LIV), 68% UT, and 5% LT. DJK patients had 25% cervical, 50% UT, and 25% LT. There were no baseline or 1Y differences for PI, PI-LL, SVA, TPA, or PT for actual and age-adjusted targets. DJK patients had worse baseline cSVA and more severe 1Y cSVA, C2–T3 SVA, and C2 slope (P < 0.05). The distribution of over/under corrected patients and the offset between actual and ideal alignment for SVA, PT, TPA, PI-LL, and LL-TK were similar between DJK and non-DJK patients. DJK patients requiring reoperation had worse postoperative changes in all cervical parameters and trended toward larger offsets for global parameters.

Conclusion:

CD patients with severe baseline malalignment went on to develop postoperative DJK. Age-adjusted alignment targets did not capture differences in these populations, suggesting the need for cervical-specific goals.

Soft Landing technique as a possible prevention strategy for proximal junctional failure following adult spinal deformity surgery

Background

This cross sectional study describes a "Soft Landing" strategy utilizing hooks for minimizing proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). The technique creates a gradual transition from a rigid segmental construct to unilateral hooks at the upper instrumented level and preservation of the soft tissue attachments on the contralateral side of the hooks. Authors devise a novel classification system for better grading of PJK severity.

Methods

Thirty-nine consecutive adult spinal deformity (ASD) patients at a single institution received the "Soft Landing" technique. The proximal junctional angle was measured preoperatively and at last follow-up using standing 36-inch spinal radiographs. Changes in proximal junctional angle and rates of PJK and PJF were measured and used to create a novel classification system for evaluating and categorizing ASD patients postoperatively.

Results

The mean age of the cohort was 61.4 years, and 90% of patients were women. Average follow up was 2.2 years. The mean change in proximal junctional angle was 8° (SD 7.4°) with the majority of patients (53%) experiencing less than 10° and only 1 patients with proximal junctional angle over 20°. Four patients (10%) needed additional surgery for proximal extension of the uppermost instrumented vertebra (UIV) secondary to PJF.

Conclusions

Soft Landing technique is a possibly effective treatment strategy to prevent PJK and PJF following ASD that requires further evaluation. The described classification system provides management framework for better grading of PJK. The "Soft Landing" technique warrants further comparison to other techniques currently used to prevent both PJK and failure.

COMPARATIVE STUDY OF THE TYPES OF FIXATION IN ADOLESCENT IDIOPATHIC SCOLIOSIS

ABSTRACT Objective: To conduct a comparative study of the results obtained in the treatment of adolescent idiopathic scoliosis (AIS) with different types of fixations (traditional, selective and multiple), and to evaluate the correction of angular deformity in the frontal plane by the Cobb and sacral clavicular angle (SCA) methods. Methods: A study of a group of 278 patients with AIS who underwent selective, traditional, and multiple fixation surgeries. Results: Significant corrections of both the Cobb angle and the SCA were observed. Conclusions: In the multiple fixation surgeries there was a 100% correction between the preoperative and postoperative SCA values and a 50% correction in the traditional and selective fixations, a difference considered significant. Regarding the Cobb angle, the three fixations presented corrections between preop and postop with significant differences. Level of evidence III; Retrospective Study.

Semitendinosus Tendon Augmentation for Prevention of Proximal Junctional Failure

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim of this study was to compare the incidence of proximal junctional kyphosis (PJK), proximal junctional failure (PJF), and clinical outcomes of patients who did and did not receive posterior ligament complex (PLC) augmentation using a semitendinosus allograft when undergoing long-segment posterior spinal fusion for adult spinal deformity.

SUMMARY OF BACKGROUND DATA

Clinical research on the augmentation of the PLC to prevent PJK and PJF has been limited to small case series without a comparable control group.

METHODS

From 2014 to 2019, a consecutive series of patients with adult spinal deformity who underwent posterior long-segment spinal fusion with semitendinosus allograft to augment the PLC (allograft) or without PLC augmentation (control) were identified. Preoperative and postoperative spinopelvic parameters were measured. PJK, PJF, and Oswestry Disability Index (ODI) scores were recorded and compared between the two groups. Univariate and multivariate analysis was performed. P ≤ 0.05 was considered significant.

RESULTS

Forty-nine patients in the allograft group and 34 patients in the control group were identified. There were no significant differences in demographic variables or operative characteristics between the allograft and control group. Preoperative and postoperative spinopelvic parameters were also similar between the two groups. PJK was present in 33% of patients in the allograft group and 32% of patients in the control group (P = 0.31). PJF did not occur in the allograft group, whereas six patients (18%) in the control group developed PJF (P = 0.01). Postoperative absolute ODI was significantly better in the allograft group (P = 0.007).

CONCLUSION

The utilization of semitendinosus allograft tendon to augment the PLC at the upper instrumented vertebrae in patients undergoing long-segment posterior spinal fusion for adult deformity resulted in a significant decrease in PJF incidence and improved functional outcomes when compared to a cohort with similar risk of developing PJK and PJFLevel of Evidence: 3.

The prevalence of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) in patients undergoing circumferential minimally invasive surgical (cMIS) correction for adult spinal deformity: long-term 2- to 13-year follow-up

OBJECTIVES

This aim of this study is to evaluate the prevalence of PJK and PJF in patients who underwent circumferential minimally invasive surgery (cMIS) for ASD.

METHODS

A prospective database of patients who underwent cMIS correction of ASD from November 2006 to July 2018 was queried. PJK was defined as angle > 10° and at least 10° greater than the baseline when measuring UIV to UIV + 2. PJF was defined as any type of symptomatic PJK which required surgery. Pre-op, latest and delta SVA and PI-LL mismatch were compared between patients with PJK and without. Only patients instrumented at 4 or more levels with full length 36″ films and a minimum 2-year follow-up were included.

RESULTS

A total of 184 patients met inclusion criteria for this study. Mean follow-up time was 85.2 months (24-158.9 months, SD 39.1). Mean age was 66 years (22-85 years). The mean number of operated levels was 6.9 levels (4-16 levels, SD 2.8). A total of 21 patients (10.8%) met PJK criteria. Only 10 (4.9%) were symptomatic (PJF) and underwent revision surgery. The other 11 patients remained asymptomatic. Comparing PJK to non-PJK patients, there was no statistically significant difference in the post-op SVA, delta SVA, post-op PI/LL and delta PI/LL between the two groups.

CONCLUSION

Our study would suggest that in the appropriately selected and well-optimized patient, CMIS deformity correction is associated with a low prevalence of PJK and PJF.

Risk Factors Associated With Failure to Reach Minimal Clinically Important Difference After Correction Surgery in Patients With Degenerative Lumbar Scoliosis

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to evaluate the factors affecting health-related quality of life (HRQOL) after surgery in patients with degenerative lumbar scoliosis (DLS) by minimum clinically important difference (MCID).

SUMMARY OF BACKGROUND DATA

MCID has been introduced in the adult spinal deformity to quantify the absolute minimum change that can be considered a success. There are limited data available to identify factors affecting reaching MCID after DLS surgery.

METHODS

This study reviewed a cohort of 123 DLS patients after correction surgery and with a minimum 2-year follow-up (FU). Inclusion criteria included age ≥40 and minimum five vertebrae fused and the availability of Scoliosis Research Society (SRS)-22 scores and radiographic data at baseline (BL) and FU. Using a multivariate analysis, two groups were compared to identify possible risk factors: those who reached MCID in the all four SRS domains (N = 65) at the last FU and those who missed MCID (N = 58).

RESULTS

At baseline, patients differed significantly from matched normative data in all SRS-22 domains. The baseline HRQOL was comparable in reached MCID and missed MCID group patients (P > 0.05). The HRQOL scores at FU were significantly higher than those at baseline. Of 123 included patients, 77.2% (N = 95), 72.4% (N = 89), 76.4% (N = 94), and 89.4% (N = 110) reached MCID in SRS pain, activity, appearance, and mental domain, respectively. Pelvic incidence (PI) >55°, lumbar lordosis (LL) loss >4.65°, coronal imbalance at FU, sagittal vertical axis (SVA) at FU >80 mm, and presence of proximal junctional kyphosis (PJK) and distal junctional problem (DJP) had negative effects on the recovery process.

CONCLUSION

Factors affecting reaching MCID after surgery for DLS were higher PI, LL loss, coronal imbalance, severe sagittal imbalance, and the occurrence of PJK and DJP.

LEVEL OF EVIDENCE

4.

Under-contouring of rods: a potential risk factor for proximal junctional kyphosis after posterior correction of Scheuermann kyphosis

OBJECTIVE

Scheuermann kyphosis (SK) could require surgical treatment in certain situations. A posterior reduction is the most widespread treatment so far, although the development of proximal junctional kyphosis (PJK) is one of the possible complications of this procedure. The contour of the proximal part of the rod could influence the occurrence of PJK in SK patients. The objective of this study was to analyze the impact of the proximal rod contour on the occurrence of a PJK complication in SK patients.

METHODS

This retrospective monocentric study was performed in the Nanjing Spine Surgery Department. All eligible patients had undergone posterior correction surgery with pedicle screws only between 2002 and 2017 and had at least 24 months of follow-up. The presence of PJK was quantified on radiographs using the proximal junctional angle (PJA > 10° at the last follow-up). The authors propose a new radiological parameter to measure the angulation of the proximal part of the instrumentation: the proximal contouring rod angle (PCRA) is the angle between the upper endplate of the upper instrumented vertebra (UIV) and the lower endplate of the second vertebra caudal to the UIV. The patients were analyzed according to the presence or absence of PJK. A t-test, receiver operating characteristic (ROC) curve analysis, and logistic regression analysis were performed for statistical analysis.

RESULTS

Sixty-two patients treated for SK were included in this study. The mean age was 18.6 ± 8.5 years, and the mean follow-up was 42.5 ± 16.4 months. The mean correction rate of global kyphosis was 46.4% ± 13.7%. At the last follow-up, 17 patients (27.4%) presented with PJK. No significant difference was found between the PJK and non-PJK groups in terms of age and other preoperative variables. A significant difference in the postoperative PCRA was found between the PJK and non-PJK groups (8.2° ± 4.9° vs 15.7° ± 6.6°, respectively; p = 0.001). A postoperative PCRA less than 10.1° predicted a significantly higher risk for PJK (p = 0.002, OR 2.431, 95% CI 1.781-4.133).

CONCLUSIONS

Under-contouring of the proximal part of the rods (lower than 10°) is a risk factor for PJK after posterior correction of SK.

Comparison of Proximal Junctional Failure and Functional Outcomes Across Varying Definitions of Proximal Junctional Kyphosis

BACKGROUND

Proximal junctional kyphosis (PJK) is a well-recognized complication following surgery for adult spinal deformity (ASD); however, definitions for PJK and its clinical implications can significantly vary by study. This study compares multiple definitions of PJK and describes incidence and clinical significance by definition.

METHODS

From 2014 to 2019, patients with ASD who underwent spinal fusion were identified. Nine definitions of PJK were created based on previously established definitions using the following upper instrumented vertebra +2 (UIV+2) sagittal Cobb measurements: A= ≥10 postoperative AND preoperative, B = ≥10 postoperative, C = ≥10 preoperative, D = ≥15 postoperative AND preoperative, E = ≥15 postoperative, F = ≥15 preoperative, G = ≥20 postoperative AND preoperative, H = ≥20 postoperative, I = >20 preoperative. Incidence of PJK was calculated by definition. Area under the curve (AUC) was calculated based on a receiver operating characteristic to assess ability to predict proximal junctional failure (PJF). Univariate analysis was performed to assess association with postoperative Oswestry Disability Index (ODI) scores.

RESULTS

Across 82 patients, the incidence of PJK and AUC by definition was as follows: A = 47%, 0.47; B = 72%, 0.65; C = 49%, 0.45; D = 27%, 0.46; E = 57%, 0.62; F = 27%, 0.46; G = 10%, 0.55; H = 40%, 0.71; I = 10%, 0.55. No definition was associated with postoperative ODI scores (P < 0.05).

CONCLUSIONS

The incidence of PJK significantly decreased with stricter definitions. Definitions utilizing only postoperative UIV+2 values had higher incidences but were more likely to capture patients who developed PJF. No definition was associated with postoperative ODI scores. UIV+2 ≥20 was best in distinguishing patients who developed PJF.

The patient demographics, radiographic index and surgical invasiveness for mechanical failure (PRISM) model established for adult spinal deformity surgery

Mechanical failure (MF) following adult spinal deformity (ASD) surgery is a severe complication and often requires revision surgery. Predicting a patient’s risk of MF is difficult, despite several potential risk factors that have been reported. The purpose of this study was to establish risk stratification model for predicting the MF based on demographic, and radiographic data. This is a multicenter retrospective review of the risk stratification for MF and included 321 surgically treated ASD patients (55 ± 19 yr, female: 91%). The analyzed variables were recorded for at least 2 yr and included age, gender, BMI, BMD, smoking status, frailty, fusion level, revision surgery, PSO, LIF, previous surgery, spinal alignment, GAP score, Schwab-SRS type, and rod materials. Multivariate logistic regression analyses were performed to identify the independent risk factors for MF. Each risk factor was assigned a value based on its regression coefficient, and the values of all risk factors were summed to obtain the PRISM score (range 0–12). We used an 8:2 ratio to split the data into a training and a testing cohort to establish and validate the model. MF developed in 41% (n = 104) of the training subjects. Multivariate analysis revealed that BMI, BMD, PT, and frailty were independent risk factors for MF (BMI: OR 1.7 [1.0–2.9], BMD: OR 3.8 [1.9–7.7], PT: OR 2.6 [1.8–3.9], frailty: OR 1.9 [1.1–3.2]). The MF rate increased with and correlated well with the risk grade as shown by ROC curve (AUC of 0.81 [95% CI 0.76–0.86]). The discriminative ability of the score in the testing cohort was also good (AUC of 0.86 ([95% CI 0.77–0.95]). We successfully developed an MF-predicting model from individual baseline parameters. This model can predict a patient’s risk of MF and will help surgeons adjust treatment strategies to mitigate the risk of MF.

Development of Proximal Junctional Kyphosis After Minimally Invasive Lateral Anterior Column Realignment for Adult Spinal Deformity

BACKGROUND

Development of proximal junctional kyphosis (PJK) after correction of adult spinal deformity (ASD) undermines sagittal alignment. Minimally invasive anterior column realignment (ACR) is a powerful tool for correction of ASD; however, long-term PJK rates are unknown.

OBJECTIVE

To characterize PJK after utilization of ACR in ASD correction.

METHODS

A retrospective multi-institution cohort analysis per STROBE criteria was conducted of all patients who underwent lateral lumbar interbody fusion (LLIF) or ACR for ASD from 2010 to 2015. All patients obtained preoperative and follow-up upright radiographs, assessing spinal alignment and development of PJK. Patients without proper imaging or minimum 1-yr follow-up were excluded.

RESULTS

A total of 73 of 112 patients who underwent either LLIF or ACR for ASD met inclusion criteria. Mean follow-up was 22.8 mo. There was significant improvement of all spinopelvic parameters. Overall, PJK and proximal junctional failure (PJF) rates were 20.5% and 11%, respectively. The incidence of PJK increased with greater corrective surgery (0% LLIF, 30% ACR, 42.9% ACR + posterior column osteotomy (PCO); P < .001). PJF rates increased (0% LLIF, 11% ACR, 40% ACR + PCO; P = .005). Risk factors included location of the upper-instrumented vertebra at T10-L1 vs L2-L4 (P = .007), age (P = .029), severity of ASD, and overcorrection of sagittal imbalance.

CONCLUSION

The incidence of PJK after minimally invasive ACR is slightly lower than reported after open surgery but greater than in LLIF only and increases with PCO utilization. The PJK rate increases when crossing the TL junction, sagittal imbalance severity, and overcorrection. Elderly patients are at an increased risk, suggesting need for age appropriate correction goals.

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

BACKGROUND

Proximal junctional kyphosis (PJK) following adult spinal deformity (ASD) surgery is a well-documented complication, but associations between radiographic PJK and cervical malalignment onset remain unexplored.

OBJECTIVE

To study cervical malalignment in ASD surgical patients that develop PJK.

METHODS

Retrospective review of prospective multicenter database. Inclusion: primary ASD patients (≥5 levels fused, upper instrumented vertebra [UIV] at T2 or above, and 1-yr minimum follow-up) without baseline cervical deformity (CD), defined as ≥2 of the following criteria: T1 slope minus cervical lordosis < 20°, cervical sagittal vertical axis < 4 cm, C2-C7 cervical lordosis < 10°. PJK presence (<10° change in UIV and UIV + 2 kyphosis) and angle were identified 1 yr postoperative. Propensity score matching between PJK and nonPJK groups controlled for baseline alignment. Preoperative and 1-yr postoperative cervical alignment were compared between PJK and nonPJK patients.

RESULTS

One hundred sixty-three patients without baseline CD (54.9 yr, 83.9% female) were included. PJK developed in 60 (36.8%) patients, with 27 (45%) having UIV above T7. PJK patients had significantly greater baseline T1 slope in unmatched and propensity score matching comparisons (P < .05). At 1 yr postoperative, PJK patients had significantly higher T1 slope (P < .001), C2-T3 Cobb (P = .04), and C2-T3 sagittal vertical axis (P = .02). New-onset CD rate in PJK patients was 15%, and 16.5% in nonPJK patients (P > .05). Increased PJK magnitude was associated with increasing T1 slope and C2-T3 SVA (P < .05).

CONCLUSION

Patients who develop PJK following surgical correction of ASD have a 15% incidence of development of new-onset CD. Patients developing PJK following surgical correction of ASD tend to have an increased preoperative T1 slope. Increased progression of C2-T3 Cobb angle and C2-T3 SVA are associated with development of PJK following surgical correction of thoracolumbar deformity.

Effectiveness of posterior structures in the development of proximal junctional kyphosis following posterior instrumentation: A biomechanical study in a sheep spine model

Introduction

Proximal junctional kyphosis – PJK has been defined by a 10 or greater increase in kyphosis at the proximal junction as measured by the Cobb angle from the caudal endplate of the uppermost instrumented vertebrae (UIV) to the cephalad endplate of the vertebrae 1 segments cranial to the UIV. In this biomechanical study, it is aimed to evaluate effects of interspinosus ligament complex distruption and facet joint degeneration on PJK development.

Materials and methods

Posterior instrumentation applied between T2 – T7 vertebrae using pedicle screws to randomly selected 21 sheeps, divided into 3 groups. First group selected as control group (CG), of which posterior soft tissue and facet joints are protected. In second group (spinosus group, SG) interspinosus ligament complex which 1 segment cranial to UIV has been transected, and third group (faset group-FG) was applied facet joint excision. 25 N, 50 N, 100 N, 150 N and 200 N forces applied at frequency of 5 Hertz as 100 cycles axial to the samples. Then, 250 N, 275 N and 300 N forces applied static axially. Interspinosus distance, kyphosis angle and discus heights was measured in radiological evaluation. Abnormal PJK was defined by a proximal junctional angle greater than 10⁰ and at least 10⁰ greater than the corresponding preoperative measurement.

Results

In CG group, average interspinosus distance was 6,6 ± 1.54 mm and kyphosis angle was 2,2 ± 0.46° before biomechanical testing, and they were measured as 9,4 ± 1.21 mm and 3,3 ±0.44° respectively after forces applied to samples. In SG group, average interspinosus distance was 6,2 ± 1.72 mm and kyphosis angle was 2,7 ± 1.01° before experiment, and they were measured as 20,8 ± 5.66 mm and 15,1 ± 2.34° respectively after forces applied to samples. In FG group, average interspinosus distance was 4,8 ± 1.15 mm and kyphosis angle was −1 ± 4.14° before experiment, and they were measured as 11,1 ±1.96mm and 11 ± 2.87° respectively after forces applied to samples. In comparison to group CG, statistically significant junctional kyphosis was seen on both FG and SG group after statistical analysis. (p < 0.05). PJK was seen statistically significant more on SG group than FG group. (p < 0.05). Not any statistically significant difference was seen on measurement of disk distances among three groups. (p > 0.05)

Conclusions

Protecting interspinosus ligament complex and facet joint unity during posterior surgical treatment for spine deformation is vital to prevent PJK development. Based on our literature review, this is the first biomechanical study that reveals interspinosus ligament complex are more effective on preventing PJK development than facet joints.

Management of Catastrophic Proximal Junctional Failure Following Spinal Deformity Correction in an Adult with Osteogenesis Imperfecta: Case Report and Technical Note

BACKGROUND

Proximal junctional failure (PJF) is a major and sometimes devastating problem following adult spinal deformity (ASD) correction surgery. Common consensus still lags on guidelines for preventing and managing these complications. Surgical treatment of scoliosis in the presence of osteogenesis imperfecta (OI) in the pediatric population is well described. The complication rates are unusually higher in this special subset of patients owing to poor quality of bone. There is a paucity of literature focusing on surgical techniques, strategies, and problems involved in the management of ASD associated with OI.

CASE DESCRIPTION

We report a 59-year-old female with type 1 OI and adult scoliosis who underwent T10-to-pelvis fusion for ASD according to the principles of adult deformity correction. At a 1-year follow-up, she presented with asymptomatic proximal junctional kyphosis of 45° and 2 weeks later had PJF along with spinal cord injury after a fall. On computed tomography scan, kyphosis was increased to 60° at T9-T10. She underwent decompression and revision deformity correction using quadruple rods, with extension of instrumentation to T2 with soft landing using rib bands. At a 4-year follow-up, she had a good functional outcome after revision surgery.

CONCLUSIONS

This is the first report of successful management of PJF following ASD correction in the presence of OI using this technique. Suboptimal hold of implants due to poor bone quality must be at the focus of any surgical planning for these patients. All possible strategies to prevent PJF must be considered when planning the deformity correction in adults with OI.

Recovery kinetics following spinal deformity correction: a comparison of isolated cervical, thoracolumbar, and combined deformity morphometries

BACKGROUND CONTEXT

The postoperative recovery patterns of cervical deformity patients, thoracolumbar deformity patients, and patients with combined cervical and thoracolumbar deformities, all relative to one another, is not well understood. Clear objective benchmarks are needed to quantitatively define a "good" versus a "bad" postoperative recovery across multiple follow-up visits, varying deformity types, and guide expectations.

PURPOSE

To objectively define and compare the complete 2-year postoperative recovery process among operative cervical only, thoracolumbar only, and combined deformity patients using area-under-the-curve (AUC) methodology.

STUDY DESIGN/SETTING

Retrospective review of 2 prospective, multicenter adult cervical and spinal deformity databases.

PATIENT SAMPLE

One hundred seventy spinal deformity patients.

OUTCOME MEASURES

Common health-related quality of life (HRQOL) assessments across both databases included the EuroQol 5-Dimension Questionnaire and Numeric Rating Scale (NRS) back pain assessment. In order to compare disability improvements, the Neck Disability Index (NDI) and the Oswestry Disability Index (ODI) were merged into one outcome variable, the ODI-NDI. Both assessments are gauged on the same scale, with minimal question deviation. Sagittal Radiographic Alignment was also assessed at pre- and all postoperative time points.

METHODS

Operative deformity patients >18 years old with baseline (BL) to 2-year HRQOLs were included. Patients were stratified by cervical only (C), thoracolumbar only (T), and combined deformities (CT). HRQOL and radiographic outcomes were compared within and between deformity groups. AUC normalization generated normalized HRQOL scores at BL and all follow-up intervals (6 weeks, 3 months, 1 year, and 2 year). Normalized scores were plotted against follow-up time interval. AUC was calculated for each follow-up interval, and total area was divided by cumulative follow-up length, determining overall, time-adjusted HRQOL recovery (Integrated Health State, IHS). Multiple linear regression models determined significant predictors of HRQOL discrepancies among deformity groups.

RESULTS

One hundred seventy patients were included (27 C, 27 T, and 116 CT). Age, BMI, sex, smoking status, osteoporosis, depression, and BL HRQOL scores were similar among groups (p >. 05). T and CT patients had higher comorbidity severities (CCI: C 0.696, T 1.815, CT 1.699, p = .020). Posterior surgical approaches were most common (62.9%) followed by combined (28.8%) and anterior (6.5%). Standard HRQOL analysis found no significant differences among groups until 1-year follow-up, where C patients exhibited comparatively greater NRS back pain (4.88 vs. 3.65 vs. 3.28, p = .028). NRS Back pain differences between groups subsided by 2-years (p>.05). Despite C patients exhibiting significantly faster ODI-NDI minimal clinically important difference (MCID) achievement (33.3% vs. 0% vs. 23.0%, p < .001), all deformity groups exhibited similar ODI-NDI MCID achievement by 2-years (51.9% vs. 59.3% vs. 62.9%, p = 0.563). After HRQOL normalization, similar results were observed relative to the standard analysis (1-year NRS Back: C 1.17 vs. T 0.50 vs. CT 0.51, p < .001; 2-year NRS Back: 1.20 vs. 0.51 vs. 0.69, p = .060). C patients exhibited a worse NRS back normalized IHS (C 1.18 vs. T 0.58 vs. CT 0.63, p = .004), indicating C patients were in a greater state of postoperative back pain for a longer amount of time. Linear regression models determined postoperative distal junctional kyphosis (adjusted beta: 0.207, p = .039) and osteoporosis (adjusted beta: 0.269, p = .007) as the strongest predictors of a poor NRS back IHS (model summary: R² = 0.177, p = .039).

CONCLUSIONS

Despite C patients exhibiting a quicker rate of MCID disability (ODI-NDI) improvement, they exhibited a poorer overall recovery of back pain with worse NRS back scores compared with BL status and other deformity groups. Postoperative distal junctional kyphosis and osteoporosis were identified as primary drivers of a poor postoperative NRS back IHS. Utilization of the IHS, a single number adjusting for all postoperative HRQOL visits, in conjunction with predictive modelling may pose as an improved method of gauging the effect of surgical details and complications on a patient's entire recovery process.

Anatomic Trajectory Screw Fixation at Upper Instrumented Vertebra Is a Substantial Risk Factor for Proximal Junctional Kyphosis

BACKGROUND

This study aimed to investigate the risk of proximal junction kyphosis (PJK) and proximal junction failure (PJF) associated with screw trajectory (straightforward vs. mixed vs. anatomic) at upper instrumented vertebra (UIV).

METHODS

A single-center, single-surgeon consecutive series of adult patients who underwent lumbar fusion for ≥4 levels (the UIV of the thoracolumbar spine, T9-L2, and the lower instrumented vertebra at the sacrum or pelvis) was retrospectively reviewed. Patients were divided into 3 groups according to UIV screw trajectory: group S, 2 straightforward screws; group M, 1 straightforward screw and 1 anatomic trajectory screw; and group A, 2 anatomic trajectory screws.

RESULTS

A total of 83 patients were included in this study, including 51 in group S, 16 in group M, and 16 in group A. The incidence of PJK in group S (12 patients, 23.5%), group M (7 patients, 43.8%), and group A (9 patients, 56.3%) significantly increased in sequence by group (P = 0.044). Anatomic trajectory screw fixation increased the risk for PJF requiring revision surgery compared with straightforward screw fixation (3 patients [18.8%] vs. 1 patient [2.0%]; P = 0.040). Multivariable analysis identified that anatomic trajectory screw fixation was a significant risk factor for PJK (P = 0.008; adjusted odds ratio = 7.591; 95% confidence interval, 1.69-34.093).

CONCLUSION

Anatomic trajectory screw fixation at the UIV is a substantial risk factor for PJK and PJF. To reduce PJK and PJF, straightforward screw fixation at the UIV is recommended in adult spinal deformity correction surgery.