J Korean Neurosurg Soc.  2021 Nov;64(6):922-932. 10.3340/jkns.2020.0311.

Posterior Thoracic Cage Interbody Fusion Offers Solid Bone Fusion with Sagittal Alignment Preservation for Decompression and Fusion Surgery in Lower Thoracic and Thoracolumbar Spine

• Shin HK
• Kim M
• Oh SK
• Choi I
• Seo DK
• Park JH
• Roh SW
• Jeon SR

• KMID: 2521982
• DOI: http://doi.org/10.3340/jkns.2020.0311

Abstract

Objective
: It is challenging to make solid fusion by posterior screw fixation and laminectomy with posterolateral fusion (PLF) in thoracic and thoracolumbar (TL) diseases. In this study, we report our experience and follow-up results with a new surgical technique entitled posterior thoracic cage interbody fusion (PTCIF) for thoracic and TL spine in comparison with conventional PLF.
Methods
: After institutional review board approval, a total of 57 patients who underwent PTCIF (n=30) and conventional PLF (n=27) for decompression and fusion in thoracic and TL spine between 2004 and 2019 were analyzed. Clinical outcomes and radiological parameters, including bone fusion, regional Cobb angle, and proximal junctional Cobb angle, were evaluated.
Results
: In PTCIF and conventional PLF, the mean age was 61.2 and 58.2 years (p=0.46), and the numbers of levels fused were 2.8 and 3.1 (p=0.46), respectively. Every patient showed functional improvement except one case of PTCIF. Postoperative hematoma as a perioperative complication occurred in one and three cases, respectively. The mean difference in the regional Cobb angle immediately after surgery compared with that of the last follow-up was 1.4° in PTCIF and 7.6° in conventional PLF (p=0.003), respectively. The mean durations of postoperative follow-up were 35.6 months in PTCIF and 37.3 months in conventional PLF (p=0.86).
Conclusion
: PTCIF is an effective fusion method in decompression and fixation surgery with good clinical outcomes for various spinal diseases in the thoracic and TL spine. It provides more stable bone fusion than conventional PLF by anterior column support.

Keyword

Decompression; Lumbar vertebrae; Posterior thoracic cage interbody fusion; Spinal fusion; Thoracic vertebrae

Figure

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  Fig. 1. A flowchart of the study. TL : thoracolumbar, PTCIF : posterior thoracic cage interbody fusion, PLF : posterolateral fusion.

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  Fig. 2. Intraoperative C-arm images in posterior thoracic cage interbody fusion procedures. A : Discectomy was performed after the incision of the annulus using knife and sharp osteotome. B : A shaver was inserted and rotated to scrub the endplate. C : The disc material was removed using a pituitary forcep. D : The remnant disc material of the endplate was curetted with an angled curette. E : Autologous bone chips were inserted into the disc space and packed by a sharp impactor to enhance bone fusion before cage insertion. F : Thereafter, cages packed with autologous bone chips were inserted.

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  Fig. 3. Images of conventional posterolateral fusion after posterior screw fixation and laminectomy images at surgical field are shown. Bone chips were applied onto the fusion bed obtained through extensive lateral muscle dissection. A : The yellow arrows indicate the local autologous bone chips. B : Allograft or hydroxyapatite bone chips can be used along with autologous bone chips. The blue arrows indicate the hydroxyapatite bone chips.

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  Fig. 4. Radiological measurement of the sagittal X-ray. The regional Cobb angle is the angle between the red tangential line to the cephalad endplate line of the upper instrumented vertebrae (UIV) (B) and the red tangential line to the caudal endplate line of the lower instrumented vertebrae (D). The proximal junctional Cobb angle is the angle between the blue tangential line to the cephalad endplate line of the two supraadjacent vertebrae above the UIV (A) and the blue tangential line to the caudal endplate line of the UIV (C).

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  Fig. 5. The changes of radiological parameters of the two groups during follow-up. A : The mean difference in the regional Cobb angle immediately after surgery compared with that of the last follow-up was 1.4° in posterior thoracic cage interbody fusion (PTCIF) and 7.6° in conventional posterolateral fusion (PLF), which showed significant difference between the two groups (p=0.003). B : The mean difference in the proximal junctional Cobb angle immediately after surgery compared with that of the last follow-up was 2.0° in PTCIF and 2.1° in conventional PLF, which showed no significant difference (p=0.97).

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  Fig. 6. Bony continuity within and circumjacent the cages between the upper and lower endplates are well identified in coronal (A) and sagittal (B) CT images 3 months after PTCIF at T12–L1, whereas it is complex to verify the bony continuity in simple spine X-ray (C) and sagittal CT image (D) 3 months after conventional PLF. PTCIF : posterior thoracic cage interbody fusion, PLF : posterolateral fusion, CT : computed tomography.

Reference

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