Effect of Electrothermal Treatment on Nerve Tissue Within the Triangular Fibrocartilage Complex, Scapholunate, and Lunotriquetral Interosseous Ligaments

Abstract

To evaluate the effect of thermal treatment on neural tissue in the triangular fibrocartilage complex (TFCC), scapholunate interosseous ligament (SLIL), and lunotriquetral interosseous ligament (LTIL). The intact TFCC, SLIL, and LTIL were harvested from cadaveric specimens and treated with a radiofrequency probe as would be performed intraoperatively. Slides were stained using a triple-stain technique for neurotrophin receptor p75, pan-neuronal marker protein gene product 9.5 (PGP 9.5), and 4',6-diamidino-2-phenylindole for neural identification. Five TFCC, 5 SLIL, and 4 LTIL specimens were imaged with fluorescence microscopy. Imaging software was used to measure fluorescence signals and compare thermally treated areas with adjacent untreated areas. A paired t test was used to compare treated versus untreated areas. P < .05 was considered significant. For the TFCC, a mean of 94.9% ± 2.7% of PGP 9.5-positive neural tissue was ablated within a mean area of 11.7 ± 2.5mm(2)(P= .02). For the SLIL treated from the radiocarpal surface, 97.4% ± 1.0% was ablated to a mean depth of 2.4 ± 0.3mm from the surface and a mean horizontal spread of 3.4 ± 0.5mm(P= .01). For the LTIL, 96.0% ± 1.5% was ablated to a mean depth of 1.7 ± 0.7mm and a mean horizontal spread of 2.6 ± 1.0mm(P= .02). Differences in the presence of neural tissue between treated areas and adjacent untreated areas were statistically significant for all specimens. Our study confirms elimination of neuronal markers after thermal treatment of the TFCC, SLIL, and LTIL in cadaveric specimens. This effect penetrates below the surface to innervated collagen tissue that is left structurally intact after treatment. Electrothermal treatment as commonly performed to treat symptomatic SLIL, LTIL, and TFCC tears eliminates neuronal tissue in treated areas and may function to relieve pain through a denervation effect.