Thermal Microcautery, a Form of Peripheral Nerve Field Stimulation for Treatment of Painful Knee Osteoarthritis: Non-Randomized Controlled Trial

Background: Thermal Microcautery (TMC) is a form of peripheral nerve field stimulation and is a technique used in Traditional Indian Medicine (Agnikarma) to manage chronic pain. The aim was to asses TMC in painful knee osteoarthritis (PKO). Methods: A non-randomized controlled trial was employed. All PKO patients on a waiting list for knee replacement were offered PNFS-TMC. Patients in the intervention group received 4 sessions (2 weeks apart) of PNFS-TMC by a pin-point tip of a metal rod. The rod was heated over a flame for 5 minutes before being used to induce a single 1 mm second-degree burn over points of tenderness. The control group was selected from the same waiting list. The primary outcome was assessed by Visual Analogue Scale (VAS) scores. The secondary outcomes were changes in levels of physical day to day activity, sleep and analgesics. Results: 16 PNFS-TMC intervention group patients and 15 control group patients were subject to analysis. Baseline VAS score was higher in PNFS-TMC group [9 ± 1.23 (95% CI 8.38 - 9.61) versus 5.93 ± 2.11 (95% CI 4.81 - 7.06) in the control, P < 0.0001]. VAS scores after 8 weeks (i.e. 4 sessions) were lower in the PNFS-TMC group [4.64 ± 2.08 (95% CI 3.57 - 5.72) versus 6.73 ± 2.01 (95% CI 5.61 - 7.85) respectively with P = 0.0058]. In the PNFS-TMC group, VAS score decreased from 9 ± 1.23 (95% CI 8.38 - 9.61) at baseline to 4.64 ± 2.08 (95% CI 3.57 - 5.72) after 4 sessions (P < 0.0001). In control group, VAS score showed a non-significant increase in VAS score from 5.93 ± 2.11 (95% CI 4.81 - 7.06) to 6.73 ± 2.01 (95% CI 5.61 - 7.85) (P = 0.2844). Results indicate reduction of pain VAS scores in the PNFS-TMC group (P < 0.0001). Eleven patients (68.7%) experienced increased capacity to perform daily physical activities P < 0.0001 and 5 (31.2%) showed no change in activity P < 0.0418. 5 (33.3%) of the patients in the control group became worse and 10 (66.7%) experienced no change. Conclusions: PNFS-TMC could offer a simple, safe, cheap and effective method of pain management in chronic PKO patients.