Does cooled radiofrequency ablation improve postoperative pain and function in patients undergoing total knee replacement surgery? A randomized controlled trial.

All patients will undergo a TKA via the surgeon’s standard technique. All patients will have a general anaesthetic, with intravenous analgesia during the operation as deemed appropriate by the anaesthetist. Antibiotic prophylaxis (cephazolin 2g) will be administered within 30 minutes of skin incision. All patients will be positioned supine on a standard operating table and the skin will be cleaned with antiseptic solution and covered with sterile drapes. For all cases, a tourniquet set at 300mgHg will be used. The operation will be performed using a midline incision and a medial parapatellar approach. Computer navigation software will be used for intra-operative guidance on alignment and prosthesis positioning (as is standard for the surgeon). The patella will be resurfaced in all cases as is routine for the surgeon involved. All patients will have local anaesthetic infiltration using 0.2% ropivacaine; all patients will receive the same dose. No suction drains will be used. The wounds will be closed in layers with an absorbable monofilament used for skin closure. The intervention will be the use of the cooled radiofrequency ablation (C-RFA) procedure of the knee in conjunction with total knee replacement (TKR) surgery. This is a procedure used for relief of pain and is a procedure commonly performed by the surgeon involved in the study. The procedure will occur in the operating theatre, once the patient is anaesthetised, prior to the commencement of the TKA operation. They will undergo four genicular nerve C-RFA. It is estimated this will add 5-10 minutes to the total operation time. This will be performed using the Avanos Coolief Radiofrequency System which will be performed with the surgeon’s standard technique, in keeping with manufacturer’s guidelines. Using fluoroscopic guidance, the surgeon will identify four anatomical bony landmarks which represent the target sites for the four genicular nerves. An insulated electrode needle will be inserted through the skin and placed within the tissues at this location and target positioning will be confirmed again with fluoroscopy. Sensory and motor testing will be performed to again confirm placement (as is recommended practice). At this stage, the radiofrequency generator will be turned on which will transmit a current of radiofrequency energy at a maximum of 0.5V through the insulated electrode. Due to the friction of charged molecules heating occurs with the generator set temperature of 60 degrees imparting a tissue temperature of 80 degrees celsius, which thermally deactivates the nerves responsible for sending pain signals to the brain. The radiofrequency energy is delivered through water-cooled electrodes, enabling more energy to be safely delivered to the target. The needle is then removed and this process will be repeated for all four locations. Patients are able to weight-bear as tolerated post-operatively. Standardised post-operative analgesia regimens will be followed and physiotherapy will be commenced on day 1 post-operatively. Patient outcomes (as described) will be recorded. During the procedure the surgeon responsible, being an investigator in the study, will identify and document any adverse events which occur. At each follow up point in the study an investigator will assess the participant and again document any adverse events which occur.