Thoracic Fusion

The thoracic spine may need stabilising for several reasons: deformity such as kyphosis or scoliosis; instability from degeneration, tumour or infection; or the need to secure the spine after a decompression or disc operation that has removed stabilising bone. Fusing the affected segments holds them in good alignment, relieves the mechanical problem, and provides a stable foundation. Because the thoracic spine is braced by the rib cage, some degenerative problems here are less common than in the more mobile regions, but where fusion is needed it is an effective solution.

Thoracic fusion is most often carried out from the back. Pedicle screws are placed into the thoracic vertebrae and connected by rods that hold the spine in the desired alignment; where deformity is being corrected, the rods are used to realign the spine. Where the cord has been decompressed, that is done at the same time. Bone graft is applied so the instrumented segments fuse over the following months, with the metalwork providing stability while this occurs. In some cases an anterior or combined approach is used, depending on the underlying problem and the correction required.

Thoracic fusion can be considered for thoracic deformity requiring correction, for instability from degeneration, tumour or infection, and to stabilise the spine after decompression or disc surgery that has affected its stability. The extent of the fusion is planned according to the pathology, the alignment, and where the construct should begin and end to avoid stressing the junctions with the neck or lower back. The decision, and the number of levels, are individualised, balancing stability and correction against preserving movement.

The evidence informs how thoracic fusion is planned, particularly around deformity and junctional problems. Studies of thoracic instrumentation for deformity, and meta-analyses of proximal junctional kyphosis after long fusions, examine the outcomes of thoracic fixation and how to reduce problems where a construct ends. Work on the role of fusion in stabilising the thoracic and thoracolumbar spine informs its use after decompression and in instability. The balanced view is that thoracic fusion is an effective, well-established way to stabilise and realign the mid-back, with careful planning of its extent central to a lasting result.

The operation is performed under general anaesthetic, usually with a hospital stay of several days. The metalwork provides immediate stability, while the fusion consolidates over the following months. Because the thoracic spine is naturally stiff, the loss of movement from fusing these levels is often well tolerated. Rehabilitation supports recovery. As with any operation there are risks, which are discussed fully beforehand. The best approach and extent of fusion for a given person are decided together.

• —Kim HJ, et al. Proximal junctional kyphosis as a distinct form of adjacent segment pathology after spinal deformity surgery: a systematic review. Spine 2012. (PMID 22885829)
• —Liu S, et al. Incidence and risk factors for proximal junctional kyphosis: a meta-analysis. Eur Spine J 2016. (PMID 26994925)
• —Kim YJ, et al. Proximal junctional kyphosis in adult spinal deformity following long instrumented posterior spinal fusion. Spine 2005. (PMID 16025035)
• —Hong JY, et al. Analysis of thoracic pedicle screw to hook instrumentation for the treatment of adult spinal deformity. Spine 2007. (PMID 17334290)