Plasma-mediated radiofrequency-based ablation (coblation) is an
electrosurgical technique currently used for tissue removal in a
wide range of surgical applications, including lumbar
microdiscectomy. In vitro and in vivo studies have shown
the technique to alter the expression of inflammatory cytokines in
the disc, increasing the levels of interleukin-8 (IL-8), which may
promote maturation and remodeling of the disc matrix.
To better understand the effect of coblation treatment, this study
characterizes the temporal and spatial pattern of healing after stab
injury to the rabbit intervertebral disc, with and without
plasma-mediated radiofrequency treatment.
A total of 23 New Zealand white rabbits.
Annular and nuclear stab injuries.
Sandwich enzyme-linked immunosorbent assay evaluated the
concentrations of cytokines tumor necrosis factor-α,
IL-1β, and IL-8. Histopathologic evaluations were performed on
whole discs and end plates. Tissue sections were stained with
Safranin-O to evaluate nucleus pulposus and annulus fibrosus
proteoglycan content and with Alcian blue for extracellular
proteoglycan content. Intradiscal leakage pressure was evaluated by
injecting methylene blue dye into the nucleus.
Animals underwent annular and nuclear stab injuries on three
consecutive lumbar discs (L2-L3 to L4-L5). The three levels were
randomly assigned into one of the three groups for treatment with a
plasma-mediated radiofrequency ablation device (TOPAZ; ArthroCare
Corp., Austin, TX, USA): active treatment of the nucleus only (SN);
active treatment of both nucleus and annulus (SNA); sham treatment.
Unstabbed/untreated discs from L5-L6 (n=5) served as normal
controls. Animals were euthanized at 4, 8, and 28 days
Tumor necrosis factor-α was detected in sham discs at 4 and 8
days, but not in coblation groups (SN or SNA); IL-1β was below
detection in all three treatment groups. Interleukin-8 levels
increased in all treatment groups at 4 and 8 days compared with
normal control, peaking at 4th day for sham and SN groups and 8th
day (p>.3) for the SNA group (a 2.5-fold increase). Pressure
measurements revealed higher leakage in the SN group, but no
statistically significant differences. Histopathology showed higher
proteoglycan production by 28 days in the SNA and SN groups compared
with sham. All three treatment groups showed ruptured annular fibers
from the stab injury, but maintained the overall architecture.
Remnants of notochordal tissue within the nucleus were evident in
all treatment groups at 4 and 8 days, but were only found in sham
group by 28 days. At this time, unlike the normal or sham controls,
the nucleus of SN and SNA discs had fibrocartilaginous tissue with
chondrocyte-like cells. Significant differences in the disc
architecture grade were only noted when comparing normal controls
with other groups by 28 days (p<.001).
Plasma-mediated radiofrequency ablation appears to have an anabolic
effect on disc cells, stimulating proteoglycan and IL-8 production
and maintaining annulus architecture. Coblation treatment appears to
reduce cellular response to proinflammatory stimuli and restore
overall disc architecture that may prove beneficial in a number of
degenerative disc paradigms. Further studies are encouraged to
investigate the therapeutic effect of the technique.