J Korean Neurosurg Soc.  2021 May;64(3):437-446. 10.3340/jkns.2020.0236.

The Fate of Proximal Junctional Vertebral Fractures after Long-Segment Spinal Fixation : Are There Predictable Radiologic Characteristics for Revision surgery?

• Jang HJ
• Park JY
• Kuh SU
• Chin DK
• Kim KS
• Cho YE
• Hahn BS
• Kim KH

• KMID: 2515500
• DOI: http://doi.org/10.3340/jkns.2020.0236

Abstract

Objective
: To investigate the radiographic characteristics of the uppermost instrumented vertebrae (UIV) and UIV+1 compression fractures that are predictive of revision surgery following long-segment spinal fixation.
Methods
: A total 27 patients who presented newly developed compression fracture at UIV, UIV+1 after long segment spinal fixation (minimum 5 vertebral bodies, lowest instrumented vertebra of L5 or distal) were reviewed retrospectively. Patients were divided into two groups according to following management : revisional surgery (group A, n=13) and conservative care (group B, n=14). Pre- and postoperative images, and images taken shortly before and after the occurrence of fracture were evaluated for radiologic characteristics
Results
: Despite similar degrees of surgical correction of deformity, the fate of the two groups with proximal junctional compression fractures differed. Immediately after the fracture, the decrement of adjacent disc height in group A (32.3±7.6 mm to 23.7±8.4 mm, Δ=8.5±6.9 mm) was greater than group B (31.0±13.9 mm to 30.1±15.5 mm, Δ=0.9±2.9 mm, p=0.003). Pre-operative magnetic resonance imaging indicated that group A patients have a higher grade of disc degeneration adjacent to fractured vertebrae compared to group B (modified Pfirrmann grade, group A : 6.10±0.99, group B : 4.08±0.90, p=0.004). Binary logistic regression analysis indicated that decrement of disc height was the only associated risk factor for future revision surgery (odds ratio, 1.891; 95% confidence interval, 1.121–3.190; p=0.017).
Conclusion
: Proximal junctional vertebral compression fractures with greater early-stage decrement of adjacent disc height were associated with increased risk of future neurological deterioration and necessity of revision. The condition of adjacent disc degeneration should be considered regarding severity and revision rate of proximal junctional kyphosis/proximal junction failures.

Keyword

Kyphosis; Reoperation; Spinal fusion/adverse effect; Postoperative complications; Fractures, Compression

Figure

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  Fig. 1. A : Wedging rate (%)=(b–a)/b×100. B : Local kyphotic cobb angle. C : Disc height around fractured vertebrae=a+b+c+d+e+f. Arrow indicated fractured vertebrae. a : anterior vertebral wall, b : posterior vertebral wall.

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  Fig. 2. Pre-operative diagnoses for long-segment spinal fixation. There was no significant difference in the distribution of pre-operative diagnoses between the two groups. Group A : revision surgery, group B : conservative care. ASD : adjacent segment disease, DLS : degenerative lumbar scoliosis, IFB : iatrogenic flat back, PTK : post-traumatic kyphosis, DLK : degenerative lumbar kyphosis.

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  Fig. 3. The amount of surgical correction in both groups analyzed by sagittal parameters measured before (pre-) and after (post-) the long-segment spinal fixation. SVA : sagittal vertical axis, PI : pelvic incidence, LL : lumbar lordosis, PT : pelvic tilt, TK : thoracic kyphosis.

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  Fig. 4. Pre-revision MRI images of three different patients in group A. Spinal cords were compressed anteriorly by herniated discs and posteriorly by buckling of hypertrophied ligament flavum. MRI : magnetic resonance imaging.

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  Fig. 5. A : A 64-year-old women with degenerative lumbar scoliosis in group A was initially managed with spinal fixation from T11 to S2 ala-iliac. Two months after the long-segment fixation, a T10 (UIV+1) compression fracture occurred and progressed gradually. After 2 years, revision surgery was performed when the patient complained of weaknesses in both legs. Note that disc space narrowed at the early stage (2 months) in spite of relatively mild compression of vertebrae. B : A 72-year-old women with degenerative lumbar scoliosis in group B was initially managed with spinal fixation from T9 to S2 ala-iliac. Three months after the long-segment fixation, a T8 (UIV+1) compression fracture occurred, but remained stable during the 2 years of follow-up. Conservative care was enough for this patient. Note that vertebral wedging and kyphotic angle immediately increased at the time of fracture (3 months), but disc height was preserved relative to disc height in Fig. 4A. UIV : uppermost instrumented vertebrae.

Reference

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