Separation Surgery, Fixation With Carbon-Fiber Implants, and Stereotactic Body Radiotherapy for Oligometastatic Spinal Disease

Abstract

The management of spinal metastases focuses on reducing symptoms and protecting the spinal cord, historically involving extracorporeal radiotherapy alone. The use of separation surgery techniques alongside high-dose radiotherapy to treat spinal metastases is a novel concept and has changed the treatment paradigm. Additionally, titanium implants have been increasingly used in cases of metastatic spinal tumours requiring adjuvant stereotactic radiotherapy (SBRT). We present the case of a 48-year-old female patient who was diagnosed with a metastatic deposit of breast cancer within L1 with an Epidural Spinal Cord Compression score greater than 1a. At the time of the diagnosis, her prognosis was estimated to be more than two years. She underwent a posterior instrumented fusion of T11-L3 vertebrae with a carbon-fibre fixation system and separation surgery (debulking of the tumour around the spinal cord). The patient was discharged on the second postoperative day achieving complete resolution of the mechanical back pain. SBRT was performed 12 weeks after the surgery. The patient regained ECOG status of 1 shortly after but sadly passed away due to multiple brain metastases 36 months following posterior fixation. Her spinal disease remained well-controlled throughout the follow-up. Carbon-fibre implants appear to be safe and relatively easy to apply. Their use, due to limited artefacts in both computed tomography and magnetic resonance imaging, makes SBRT much more straightforward and follow-up imaging easier to be interpreted. Our experience demonstrates that, in conjunction with separation surgery, the translucent, low perturbing properties of these implants can improve SBRT intervention and detection of recurrence on follow-up imaging.

Keywords: breast cancer; carbon fibre implants; separation surgery; spinal metastasis; stereotactic radiosurgery.

Figure 1. Preoperative computed tomography scan of the lumbosacral spine and pelvis.

A: axial views showing a significant amount of lysis to the vertebral body and both pedicles of L1 with some volume of the epidural disease. B: sagittal cuts demonstrating the extent of the involvement of the anterior column and early signs of pathological fracture to both superior and inferior endplates. C: small lytic lesion reported as likely to represent a metastasis with the right iliac crest. This was felt to be accessible for stereotactic radiotherapy and treated subsequently.

Figure 2. Positron emission tomography-computed tomography findings.

Scan showing metabolically avid lesion within the vertebral body L1 concordant with the report of the plain computed tomography. There were no other soft-tissue or bony metastases revealed apart from the aforementioned small iliac crest deposit. A: coronal section; B: axial cut at the level of L1.

Figure 3. Intraoperative fluoroscopy.

Radiolucent pedicle screw made of carbon fibre and coated with a 0.1 mm layer of titanium to ensure intraoperative visualisation marked with the asterisks. Complete bilateral pediculectomy can be visualised with the arrows. A: lateral view; B: anteroposterior view.

Figure 4. Postoperative magnetic resonance imaging scan obtained prior to stereotactic radiotherapy.

T1-weighted images with intravenous gadolinium contrast. A: axial cut at the level of T12. Note carbon-fibre screws with minimal artefacts and good visibility of the content of the spinal canal. B: axial cut at the level of L1 with enhancing postoperative changes within the resection cavity and no compression of the theca, facilitating safe delivery of stereotactic radiotherapy.

Figure 5. Postoperative computed tomography scan obtained 10 months following the stereotactic radiotherapy.

A: sagittal reconstruction showing the calcified ventral aspect of the vertebral body L1 and no active metastatic disease. B: axial cut at the level of L1 showing calcification with the irradiated tumour and carbon-fibre implants. Note the complete lack of artefacts.