Recurrence of proximal junctional kyphosis after revision surgery for symptomatic proximal junctional kyphosis in patients with adult spinal deformity: incidence, risk factors, and outcomes

Revision surgery for proximal junctional failure: A single-center analysis

BACKGROUND

Proximal junctional kyphosis (PJK) is a radiographic complication following adult spinal deformity (ASD) surgery due to degeneration of mobile segments adjacent to fused spine. Proximal junctional failure (PJF) represents PJK with structural failure, neurologic deficit, or mechanical instability warranting revision with extension of fusion above the uppermost instrumented vertebra (UIV). This study investigates the clinical presentation, mechanisms of failure, revision strategies, and outcomes for ASD patients who develop PJF after instrumented fusion to the pelvis.

METHODS

Fifty-four ASD patients who developed PJF after a posterior instrumented fusion to the pelvis at a single institution from 2009 to 2021 were analyzed. PJF was defined by radiographic PJK with (1) UIV or UIV+1 fracture, UIV screw pullout, or soft-tissue posterior ligamentous disruption, and (2) neurological deficit at presentation.

RESULTS

The cohort was stratified into upper thoracic (UT, 10 patients, T2-T6), lower thoracic (LT, 35 patients, T8-T11), and lumbar (L, 9 patients, L1-L3) spine UIV groups based on index surgery. Patients developed PJF at a median of 14 months (mean 18 ± 16, range: 1-78) after their index surgery. Neurological deficits at presentation included radiculopathy (61 %), myelopathy (48 %), motor deficits (33 %), and bowel or bladder incontinence (9 %). Mechanisms of PJF were vertebral fracture and screw pullout (UT: 50 %, LT: 80 %, L: 89 %, P < 0.001) or soft-tissue disruption (UT: 50 %, LT: 20 %, L: 11 %, P = 0.089) at the UIV. Revision surgery commonly involved posterior column osteotomies (63 %) rather than three-column osteotomies (9 %). Of patients in the UT group, 40 % were extended above the cervicothoracic junction. In the LT and L groups, 91 % and 89 % of patients were extended to the UT and LT spine, respectively. Median follow-up for the cohort after revision for PJF was 24 months (range: 2-89). A total of 26 patients (48 %) required a second revision surgery (median 14 months, range: 1-50), 16 of whom (28 %) were revised for recurrent PJF. Patient-specific and radiographic risk factors for recurrent PJF could not be elucidated.

CONCLUSION

In this series of ASD patients, after revision for PJF, recurrent PJF was the most common complication requiring another revision. Junctional failures tended to be vertebral body fracture and screw pullout in the LT and L spine and soft tissue disruption in the UT spine. Most revisions involved posterior column osteotomies with proximal extension across the thoracolumbar junction or apex of thoracic kyphosis (e.g., L to LT, LT to UT); notably, nearly half of UT failures were not extended to the cervical spine. Future research is warranted to elucidate risk factors for recurrent PJF and potential preventative strategies.

An evidence based conceptual framework for the multifactorial understanding of proximal junctional kyphosis

Introduction

Adult spinal deformity (ASD) is a debilitating pathology that arises from a variety of etiologies. Spinal fusion surgery is the mainstay of treatment for those who do not achieve symptom relief with conservative interventions. Fusion surgery can be complicated by a secondary deformity termed proximal junctional kyphosis (PJK).

Research question

This scoping review evaluates the modern body of literature analyzing risk factors for PJK development and organizes these factors according to a multifactorial framework based on mechanical, tissue or demographic components.

Materials and methods

An extensive search of the literature was performed in PubMed and Embase back to the year 2010. Articles were assessed for quality. All risk factors that were evaluated and those that significantly predicted the development of PJK were compiled. The frequency that a risk factor was predictive compared to the number of times it was evaluated was calculated.

Results

150 articles were reviewed. 57.3% of papers were of low quality. 76% of risk factors analyzed were focusing on the mechanical contribution to development of PJK versus only 5% were focusing on the tissue-based contribution. Risk factors that were most frequently predictive compared to how often they were analyzed were Hounsfield Units of vertebrae, UIV disc degeneration, paraspinal muscle cross sectional area and fatty infiltration, ligament augmentation, instrument characteristics, postoperative hip and lower extremity radiographic metrics, and postoperative teriparatide supplementation.

Discussion and conclusion

This review finds a multifactorial framework accounting for mechanical, patient and tissue-based risk factors will improve the understanding of PJK development.

The Benefit of Addressing Malalignment in Revision Surgery for Proximal Junctional Kyphosis Following ASD Surgery

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Understand the benefit of addressing malalignment in revision surgery for proximal junctional kyphosis (PJK).

SUMMARY OF BACKGROUND DATA

PJK is a common cause of revision surgery for adult spinal deformity patients. During a revision, surgeons may elect to perform a proximal extension of the fusion, or also correct the source of the lumbopelvic mismatch.

MATERIALS AND METHODS

Recurrent PJK following revision surgery was the primary outcome. Revision surgical strategy was the primary predictor (proximal extension of fusion alone compared with combined sagittal correction and proximal extension). Multivariable logistic regression determined rates of recurrent PJK between the two surgical groups with lumbopelvic surgical correction assessed through improving ideal alignment in one or more alignment criteria [Global Alignment and Proportionality (GAP), Roussouly-type, and Sagittal Age-Adjusted Score (SAAS)].

RESULTS

A total of 151 patients underwent revision surgery for PJK. PJK occurred at a rate of 43.0%, and PJF at 12.6%. Patients proportioned in GAP postrevision had lower rates of recurrent PJK [23% vs. 42%; odds ratio (OR): 0.3, 95% confidence interval (CI): 0.1-0.8, P =0.024]. Following adjusted analysis, patients who were ideally aligned in one of three criteria (Matching in SAAS and/or Roussouly matched and/or achieved GAP proportionality) had lower rates of recurrent PJK (36% vs. 53%; OR: 0.4, 95% CI: 0.1-0.9, P =0.035) and recurrent PJF (OR: 0.1, 95% CI: 0.02-0.7, P =0.015). Patients ideally aligned in two of three criteria avoid any development of PJF (0% vs. 16%, P <0.001).

CONCLUSIONS

Following revision surgery for PJK, patients with persistent poor sagittal alignment showed increased rates of recurrent PJK compared with patients who had abnormal lumbopelvic alignment corrected during the revision. These findings suggest addressing the root cause of surgical failure in addition to proximal extension of the fusion may be beneficial.

Proximal Junctional Failure in Adult Spinal Deformity Surgery: An In-depth Review

Adult spinal deformity (ASD) surgery aims to correct abnormal spinal curvature in adults, leading to improved functionality and reduced pain. However, this surgery is associated with various complications, one of which is proximal junctional failure (PJF). PJF can have a significant impact on a patient's quality of life, necessitating a comprehensive understanding of its causes and the development of effective management strategies. This review aims to provide an in-depth understanding of PJF in ASD surgery. PJF is a complex complication resulting from a multitude of factors including patient characteristics, surgical techniques, and postoperative management. Age, osteoporosis, overcorrection of sagittal alignment, and poor bone quality are identified as significant risk factors. The clinical implications of PJF are substantial, often requiring revision surgery and causing a considerable decrease in patients' quality of life. Prevention strategies include careful preoperative planning, appropriate patient selection, and optimization of surgical techniques. Treatment often necessitates a multifaceted approach, including surgical intervention and the management of underlying risk factors. Predictive modeling is an emerging field that may offer a promising avenue for the risk stratification of patients and individualized preventive strategies. A thorough understanding of PJF's pathogenesis, risk factors, and clinical implications is essential for surgeons involved in ASD surgery. Current preventive measures and treatment strategies aim to mitigate the risk and manage the complications of PJF, but the complication cannot be entirely prevented. Future research should focus on the development of more effective preventive and treatment strategies, and predictive models could be valuable in this pursuit.

Proximal junctional failure in primary thoracolumbar fusion/fixation to the sacrum/pelvis for adult symptomatic lumbar scoliosis: long-term follow-up of a prospective multicenter cohort of 160 patients

OBJECTIVE

Proximal junctional failure (PJF) is a severe form of proximal junctional kyphosis. Previous reports on PJF have been limited by heterogeneous cohorts and relatively short follow-ups. The authors' objectives herein were to identify risk factors for PJF and to assess its long-term incidence and revision rates in a homogeneous cohort.

METHODS

The authors reviewed data from the Adult Symptomatic Lumbar Scoliosis 1 trial (ASLS-1), a National Institutes of Health-sponsored prospective multicenter study. Inclusion criteria were an age ≥ 40 years, ASLS (Cobb angle ≥ 30° and Oswestry Disability Index [ODI] ≥ 20 or Scoliosis Research Society revised 22-item questionnaire [SRS-22r] score ≤ 4.0 in pain, function, or self-image domains), and primary thoracolumbar fusion/fixation to the sacrum/pelvis of ≥ 7 levels. PJF was defined as a postoperative proximal junctional angle (PJA) change > 20°, fracture of the uppermost instrumented vertebra (UIV) or UIV+1 with > 20% vertebral height loss, spondylolisthesis of UIV/UIV+1 > 3 mm, or UIV screw dislodgment.

RESULTS

One hundred sixty patients (141 women) were included in this analysis and had a median age of 62 years and a mean follow-up of 4.3 years (range 0.1-6.1 years). Forty-six patients (28.8%) had PJF at a median of 0.92 years (IQR 0.14, 1.23 years) following surgery. Based on Kaplan-Meier analyses, PJF rates at 1, 2, 3, and 4 years were 14.4%, 21.9%, 25.9%, and 27.4%, respectively. On univariate analysis, PJF was associated with greater age (p = 0.0316), greater body mass index (BMI; p = 0.0319), worse baseline patient-reported outcome measures (PROMs; ODI, SRS-22r, and SF-12 Physical Component Summary [PCS]; all p < 0.04), the use of posterior column osteotomies (PCOs; p = 0.0039), and greater postoperative thoracic kyphosis (TK; p = 0.0031) and PJA (p < 0.001). The use of UIV hooks was protective against PJF (p = 0.0340). On regression analysis (without postoperative measures), PJF was associated with greater BMI (HR 1.077, 95% CI 1.007-1.153, p = 0.0317), lower preoperative PJA (HR 0.607, 95% CI 0.407-0.906, p = 0.0146), and greater preoperative TK (HR 1.362, 95% CI 1.082-1.715, p = 0.0085). Patients with PJF had worse PROMs at the last follow-up (ODI, SRS-22r subscore and self-image, and SF-12 PCS; p < 0.04). Sixteen PJF patients (34.8%) underwent revision, and PJF recurred in 3 (18.8%).

CONCLUSIONS

Among 160 primary ASLS patients with a median age of 62 years and predominant coronal deformity, the PJF rate was 28.8% at a mean 4.3-year follow-up, with a revision rate of 34.8%. On univariate analysis, PJF was associated with a greater age and BMI, worse baseline PROMs, the use of PCOs, and greater postoperative TK and PJA. The use of UIV hooks was protective against PJF. On multivariate analysis (without postoperative measures), a higher risk of PJF was associated with greater BMI and preoperative TK and lower preoperative PJA.