Novel Application of Cooled Radiofrequency Ablation for Pain Management after Total Knee Arthroplasty.

TKR surgery will be carried out according to the investigating surgeon's standard protocol, described below. After the patient is anesthetised, the skin is cleaned with antiseptic solution and covered with sterile drapes. An incision is made down the middle of the knee of about 20cm in length. The knee joint is then visible and is cut and the patella is pushed to one side. The ends of the femur and tibia are cut using a bone saw. In some cases, the underside of the knee cap is removed. Using measuring devices, the new artificial knee joints (made of tantalum) are fitted into position and once the surgeon is satisfied with the positioning and movements of the knee, the tissue and skin are closed in layers with dissolvable sutures. These sutures do not need to be removed but the wound remains covered until healing is complete (around 10-14 days). Prior to wound closure, the intervention will be administered which involves additional treatment with the Avanos Coolief Cooled Radiofrequency System. This involves the use of a radiofrequency generator that transmits a small current of radiofrequency energy through an insulated electrode that is placed within the tissues. Due to the friction of charged molecules, heating occurs and thermally deactivates the nerves responsible for sending pain signals to the brain. Radiofrequency energy is delivered through water-cooled electrodes, enabling more energy to be safely delivered to the target areas. The frequency of the system is 460khz which delivers an attenuated charge. The amplitude is a factor of impedance and ramp time to get to the 60degree set point. This lower intensity technique makes the risk of permanent or irreversible damage to the tissues very unlikely. The application of the Coolief Cooled Radiofrequency System will add 5-10 minutes to the surgery time. Wounds will be closed in the standard fashion described above and standard post-operative care will be given. Patients are monitored closely in hospital for 3-5 days by nursing and medical staff before returning home. Patients are able to weight-bear, mobilise and commence rehabilitation immediately after surgery. In addition to standard hospital care, standard post-operative care is given by the investigating surgeon and his direct staff. This involves monitoring of pain levels and opioid intake daily for the first 3-5 days and then weekly until the 6 week mark. These are recorded in the patient’s hospital notes and confidential file which ensures close monitoring of the patients safety at all times. The additional treatment will be delivered by the investigating surgeon; a highly skilled orthopaedic surgeon with over 30 years’ experience. All procedures will be conducted at the Mater Hospital Sydney in conjunction with North Sydney Orthopaedic and Sports Medicine Centre.