Tag: Proximal junctional kyphosis

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Incidence and risk factors of adjacent segment degeneration in lumbosacral or lumbo-iliac fusion with L2 as the uppermost instrumented vertebra

J Neurosurg Spine 44:693–703, 2026

This clinical retrospective study evaluates the incidence and risk factors for symptomatic adjacent segment degeneration (ASD) after instrumented fusion from L2 to the sacrum or ilium in 89 adults treated for diffuse lumbar degeneration or mild–moderate deformity. Over a mean 38.6-month follow-up, 40% developed symptomatic L1–2 ASD and 23.6% required revision, with Kaplan-Meier ASD-free rates of 79% at 1 year and 59% at 3 years.

Multivariate analysis identified L2–3 decompression, preexisting advanced L1–2 disc degeneration, greater postoperative PI–LL mismatch, and higher lordosis distribution index as independent ASD risk factors; distal failures (13.5%) were linked to male sex, younger age, and absence of iliac screws. The authors recommend careful selection of L2 as UIV, balanced lordosis restoration, and consideration of pelvic fixation to mitigate proximal and distal complications.

Aim Quantify incidence of symptomatic adjacent segment degeneration (ASD) after instrumented fusion from L2 (UIV) to sacrum or ilium and identify associated risk factors.

Design/definition Retrospective review (Jan 2016–Dec 2023) of adults undergoing first-time L2–S1/ilium fusion; symptomatic ASD defined by new/worsening pain or neurologic symptoms with L1–2 degenerative/junctional changes (e.g., disc degeneration/stenosis progression, listhesis, junctional kyphosis, fracture, or UIV fixation failure).

Cohort 89 patients (mean age 68.5 years) with mean follow-up 38.6 months.

ASD incidence 36/89 (40%) developed symptomatic ASD at L1–2; mean time to ASD 21 months; 21/89 (23.6%) required reoperation.

ASD-free survival Kaplan-Meier ASD-free rates: 79% at 1 year, 68% at 2 years, 59% at 3 years (mean ASD-free period 52.8 months).

ASD risk factors Higher ASD risk associated with simultaneous decompression at L2–3, preexisting advanced L1–2 disc degeneration, greater postoperative PI-LL mismatch, and higher lordosis distribution index (LDI).

Distal failure incidence 12/89 (13.5%) developed distal failure (including 9 L5–S1 pseudarthroses, 2 sacral fractures, 1 rod fracture); mean time 19 months.

Distal failure risk factors Male sex, younger age, and lack of iliac screws increased risk of distal failure.

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Long-Term Clinical Benefits of Age-Adjusted Sagittal Correction in Adult Spinal Deformity Surgery

Neurosurgery 98:1040–1050, 2026

This study evaluates long-term clinical outcomes of age-adjusted sagittal alignment correction in adult spinal deformity (ASD) surgery by integrating PI–LL, pelvic tilt, T1 pelvic angle, and SVA. Using hierarchical cluster analysis on 386 patients with long-segment fusion, three postoperative alignment patterns emerged—undercorrected, matched, and overcorrected—correlated with differing radiographic trajectories and complication rates.

Patients in the matched-correction cluster achieved the best balance of clinical improvement (ODI and SRS-22r) and minimized proximal junctional kyphosis/failure, while overcorrection increased mechanical complications despite stronger radiographic correction. The results support a multi-parameter, age-adjusted strategy and propose cluster-derived offset ranges as practical surgical benchmarks.

Aim Evaluate long-term benefits of age-adjusted sagittal alignment in adult spinal deformity surgery by integrating PI–LL, PT, TPA, and SVA using hierarchical cluster analysis.

Cohort Retrospective review of 386 ASD patients undergoing ≥5-level fusion including sacrum/pelvis, with minimum 2-year follow-up (mean follow-up 36.6 months).

Targeting method Postoperative offsets (target − current) for PI–LL, PT, TPA, and SVA were computed using published age-adjusted formulas from 6-week radiographs (or immediate postop if early PJK).

Clustering outcome Patients stratified into 3 clusters (A: 72, B: 211, C: 103) with cluster A undercorrected, cluster B balanced/matched, and cluster C overcorrected trends across all parameters.

Mechanical complications PJK/PJF rates differed by cluster, highest in cluster C (37.9%) vs cluster B (27.5%) and cluster A (20.9%) (P = .046).

Patient-reported outcomes At final follow-up, cluster B had significantly better ODI and SRS-22r outcomes than clusters A and C.

Parameter relationships Offsets showed strong correlations: PI–LL with PT (r = 0.77) and PI–LL with TPA (r = 0.79); weaker with SVA (r = 0.43).

Practical implication A balanced multi-parameter alignment profile (cluster B) best optimized outcomes while reducing complications, supporting integrating multiple sagittal targets rather than relying on a single parameter.

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The Effect of Transpedicular Injection of Recombinant Human Bone Morphogenetic Protein-2/Beta-Tricalcium Phosphate Carrier on the Prevention of Proximal Junctional Kyphosis in Adult Spinal Deformity Surgery: A Pilot Study

Neurosurgery 96:986–996, 2025

The study explores the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) with beta-tricalcium phosphate (β-TCP) to prevent proximal junctional kyphosis (PJK) in adult spinal deformity surgery. Results indicate reduced PJK incidence and increased bone density at the upper instrumented vertebra.

• The study explores the use of transpedicular injection of recombinant human bone morphogenetic protein-2 (rhBMP-2) with a beta-tricalcium phosphate (β-TCP) carrier to prevent proximal junctional kyphosis (PJK) in adult spinal deformity (ASD) surgery.

• 25 patients received rhBMP-2 injections, and their outcomes were compared with two control groups with 66 and 63 patients each.

• Results showed a significantly lower incidence of PJK in the rhBMP-2 group compared to control groups.

• The injection also led to a significant increase in trabecular bone density at the upper instrumented vertebra (UIV).

• Multivariate analysis indicated that rhBMP-2 injection at the UIV had a protective effect against PJK.

• The study suggests that this method can be easily integrated into surgical procedures to enhance bone density and reduce PJK risk.

• Limitations include the small sample size and lack of randomization, warranting further studies.

• The study concludes that rhBMP-2/β-TCP injection is a promising strategy for preventing PJK in ASD surgery.

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Gravity Line–Hip Axis Offset as a Guide for Global Alignment to Prevent Recurrent Proximal Junctional Kyphosis/Failure

Operative Neurosurgery 26:268–278, 2024

Proximal junctional kyphosis/failure (PJK/F) is a potentially serious complication after adult spinal deformity (ASD) corrective surgery. Recurrent PJK/F is especially troublesome, necessitating fusion extension and occasionally resulting in irreversible neurological deficits. The gravity line (GL) offers valuable insights into global sagittal balance. This study aims to examine the postoperative GL–hip axis (GL-HA) offset as a critical risk factor for recurrent PJK/F.

METHODS: We retrospectively reviewed patients with ASD who had undergone revision surgery for initial PJK/F at a single academic center. Patients were categorized into 2 groups: nonrecurrent PJK/F group and recurrent PJK/F group. Demographics, surgical characteristics, preoperative and postoperative parameters of spinopelvic and global alignment, and the Scoliosis Research Society-22 scores were assessed. We examined these measures for differences and correlations with recurrent PJK/F.

RESULTS: Our study included 32 patients without recurrent PJK/F and 28 patients with recurrent PJK/F. No significant differences were observed in baseline demographics, operative characteristics, or Scoliosis Research Society-22 scores before and after surgery. Importantly, using a cutoff of À52.6 mm from logistic regression, there were considerable differences and correlations with recurrent PJK/F in the postoperative GL-HA offset, leading to an odds ratio of 7.0 (95% CI: 1.94-25.25, P = .003).

CONCLUSION: Postoperative GL-HA offset serves as a considerable risk factor for recurrent PJK/F in patients with ASD who have undergone revision surgery. Overcorrection, with GL-HA offset less than À5 cm, is associated with recurrent PJK/F. The instrumented spine tends to align the GL near the HA, even at the cost of proximal junction.

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Thoracolumbar Junction Orientation: A Novel Guide for Sagittal Correction and Proximal Junctional Kyphosis Prediction in Adult Spinal Deformity Patients

Neurosurgery (88), Issue 1, 2021:  55–62

Novel radiographic sagittal parameters of the thoracolumbar junction orientation (TLJO, thoracolumbar slope [TLS] and thoracolumbar tilt [TLT]) have been introduced and correlated with lumbopelvic parameters and thoracic kyphosis.

OBJECTIVE: To determine a predictive model for reciprocal thoracic kyphosis and proximal junctional kyphosis (PJK) based on the TLJO.

METHODS: A total of 127 patients who had fusion from sacrum to T10-L2 from 2004 to 2014 were reviewed. TK (T5-T12), PI, SS, PT, LL, and proximal junctional angle (PJA) were measured preoperatively, 6wk postoperatively, and at final follow-up. TLJO was measured by TLS and TLT. Changes between time points were determined (preop-6 wk =ΔParameter(Pre6wk) and preop-final follow/up =ΔParameter(PreFinal)). Scoliosis Research Society (SRS) and Oswestry Disability Index (ODI) questionnaires were evaluated at final follow-up. Patients were divided into 2 groups based on the presence of PJK (PJAPreFinal >15◦). Independent t-tests and receiver operating characteristic (ROC) curves were used to investigate the significance of differences and cut-off values. Pearson correlations and linear regressions were used to analyze the entire cohort to determine the relationship between the changes in parameters.

RESULTS: Compared to patients without PJK (n = 100), those with PJK (n = 27) had significantly lower SRS scores and significantly greater TKPreFinal, LLPre6wk, and TLSPre6wk. To maintain in the nonPJK group, ROC curves demonstrated a cut-off value of −9.4◦ for TLSPre6wk. PJK was significantly correlated with TKPreFinal and TLSPre6wk. The linear correlation revealed that TLSPre6wk < −25.3◦ is the risk factor of PJK > 15◦.

CONCLUSION: As change of TLS reflects lumbopelvic realignment and influences reciprocal TK, reducing the change of TLS may be a sagittal realignment guideline to reduce the risk of PJK.

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Different Risk Factors of Proximal Junctional Kyphosis and Proximal Junctional Failure Following Long Instrumented Fusion to the Sacrum for Adult Spinal Deformity

Neurosurgery 80:279–286, 2017

The failure modes, time to development, and clinical relevance are known to differ between proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). However, there are no reports that study the risk factors of PJK and PJF separately.

OBJECTIVE: The aim of this study was to investigate the risk factors for PJK and PJF separately.

METHODS: A retrospective study of 160 consecutive patients who underwent a long instrumented fusion to the sacrum for adult spinal deformity with a minimum follow-up of years was conducted. A separate survivorship analysis of PJK and PJF was performed using the Cox proportional hazards model for the 3 categorical parameters of surgical, radiographic, and patient factors.

RESULTS: PJK developed in 27 patients (16.9%) and PJF in 29 patients (18.1%). The median survival time was 17.0 months for PJK and 3.0 months for PJF. Multivariate analyses revealed that a high body mass index was an independent risk factor for PJK (hazard ratio [HR] = 1.179), whereas the significant risk factors for PJF were older age, the presence of osteoporosis, the uppermost instrumented vertebra level at T11-L1, and a greater preoperative sagittal vertical axis (HR = 1.082, 6.465, 5.236, and 1.017, respectively). A large correction of sagittal deformity was shown to be a risk factor for PJF on univariate analyses, but not on multivariate analyses.

CONCLUSION: PJK developed at a median of 17 months and PJF at a median of 3 months. A high body mass index was an independent risk factor for PJK, whereas older age, osteoporosis, uppermost instrumented vertebra level at the thoracolumbar junction, and greater preoperative sagittal vertical axis were risk factors for PJF.

 

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