To study and evaluate the effect of using the Primary Relief PENS treatment as adjuvant analgesia for reducing pain in total knee replacement (TKR) patients.

It is a common knowledge that total knee replacement (TKR) surgeries produce great deal of pain in the postoperative period. Superior pain relief is justifiably needed and usually provided. In addition to the conventional methods of pain relief such as continuous epidural block, intrathecal adjuvants, femoral nerve block ± sciatic nerve block, transcutaneous electrical nerve stimulation (TENS) and percutaneous electrical neurostimulation (PENS) have been reported effective by various authors. Recently neurostimulation of auricular nerves via the external auricular surface has shown to alleviate pain after caesarian section. Primary Relief® is percutaneous electrical neuro stimulator designed to administer auricular neurostimulation treatment over 240 hours. Stimulation is performed by sending electrical pulses emitted through needles strategically positioned in the ear. The ear provides numerous points for stimulation within a small area Based on the area of pain relief, chosen points are stimulated. Primary Relief is a miniaturized device designed to administer PENS treatment. Use of this device is recommended for pre-operative, intra-operative and post-operative pain therapy as well as for the treatment of chronic pain.

An advantage over drug therapy is that it avoids the possible side-effects of analgesics and helps in early mobilization following orthopedic surgeries including total knee replacement (TKR), total hip replacement (THR) and shoulder surgeries. Therefore, this study is being undertaken to assess the effect of Primary Relief ® in augmenting pain relief after TKR surgery.

Inclusion Criteria:

Patients undergoing TKR under regional or general anesthesia and femoral nerve block who consent to participate in the study.

Exclusion Criteria:

• ASA 3 or 4
• Those receiving psychiatric medication
• Those with infection at the site of application.

The following data will be collected

• Intraoperative use of local anesthetics, opioids and other analgesics
• Postoperative details as to the time of application of the device. NPRS in both the groups at multiple intervals, on demand analgesic requirement, overall analgesic consumption during the study period, quality of life questionnaire at the end of the study period and relevant postoperative complications will be noted.
• Rescue analgesics will be considered for breakthrough pain or NPRS > 4. Intravenous Tramadol 50mg will be the first rescue analgesic and if pain is not relieved with Tramadol, opiods will be considered. Non steroidal anti inflammatory drugs will be considered to supplement the above medications if there is no contraindication and if need arises.
• NPRS score will be noted at multiple intervals for 10 days.
• Any nausea, vomiting, giddiness, intolerance to the device will also be noted.
• During the follow up, quality of life questionnaire would be administered and the result noted.

The device will be removed after 10 days of its application. Any redness at the site of application or pain at the site are noted. The study will end with the removal of the device.