TUMOR ABLATION USING LASER INDUCED THERMO-THERAPY PRE-VERTEBROPLASTY AFFECTS BIOMECHANICAL STABILITY AND CEMENT FILL FOR VERTEBRAE WITH SIMULATED LYTIC METASTASES

Abstract

Vertebroplasty (VP) is currently used to improve spinal stability in patients with vertebral metastases. This study assessed the effects of Laser Induced Thermo Therapy (LITT), a minimally invasive technique used to ablate tumor tissue prior to vertebroplasty. Load-induced canal narrowing (LICN) was measured pre and post-vertebroplasty in twelve paired spinal motion segments with simulated lytic metastases. LICN improved post-vertebroplasty for all specimens treated with LITT. In all specimens, cement location was an important factor in post-vertebroplasty stability. Reduction of the tumor volume pre-vertebroplasty resulted in more reliable defect filling.

To investigate the effect of tumor ablation using Laser Induced Thermo Therapy (LITT) prior to vertebroplasty (VP) on cement distribution and vertebral stability.

Tumor volume reduction using LITT prior to cement injection improves defect filling and consistently reduces Load Induced Canal Narrowing (LICN).

A simple, minimally invasive procedure providing accurate tissue destruction pre-vertebroplasty may result in more reliable cement fill, reduce cement extravasation and improve post-vertebroplasty stability.

Following verebroplasty, LICN improved in all specimens treated with LITT and in those VP alone specimens with cement located posterior to the tumor tissue (33%). LITT treated vertebrae exhibited a trend toward reduced posterior wall motion post-vertebroplasty (LICN=29.7±27.1%) versus specimens treated with VP alone (LICN=248.7±253%). In the LITT+VP group, cement was fully contained within the vertebral body while cement extravasation into the canal was noted in 33% of the specimens treated without LITT.

Twelve paired cadaveric thoracolumbar spinal motion segments with simulated lytic metastases were randomized for treatment with VP alone or LITT+VP. In the LITT+VP group, a laser fibre inserted through a transpedicular approach was used to ablate the tumor tissue prior to cement injection. The specimens were axially loaded to 800N pre and post-treatment. LICN was used as a measure of vertebral stability. Cement location was assessed post-testing through axial sectioning. Location of cement is an important factor in determining post-VP stability. Vertebroplasty is effective in decreasing LICN if the tumor is ablated or surrounded posteriorly with cement.

Funding: USAMRMC DAMD 17–00–1–0693