Cryoneurolysis is a regional anaesthetic technique that works by freezing peripheral sensory nerves. This technique can potentially provide analgesia after total knee arthroplasty (TKA). However, the technique is expensive and comprehensive. Pain 24 hours after surgery is associated with high amounts of late acute pain. Therefore, the aim of the current study was to compare the effect of postoperative cryoanalgesia with a sham treatment on acute postoperative pain in TKA patients with moderate to severe pain on the first postoperative day. The cryoanalgesia treatment will be performed 24 hours after surgery. Afterward, the patients will be followed for 24 weeks to determine the level of pain among other outcomes.
Age ≥ 18
Primary unilateral total knee arthroplasty
Ability to participate in the study (understand written and spoken Danish language, self-reported pain and satisfaction)
Signed written informed consent form
Ongoing treatment of systemic glucocorticoids or other immunosuppressant treatment apart from inhaled steroids
Insulin-dependent diabetes
Pregnancy or breastfeeding
Mental disability that could impair a patient's decision-making capability of giving informed consent and not enabling valid data collection.
Parallel
Cryoneurolysis
Procedure/SurgeryLocal anesthesia is injected in the skin. The superficial genicular nerves, more specifically the ISN and the AFCN, are visualized. A nerve stimulator is used to verify the visualized nerves., 2-3 ml of ropivacaine 5 mg/ml is injected around the nerves. After 5-15 minutes the effect is evaluated by assessing pain in the surgical area and asking the patient whether there is a pain relief. Following this evaluation, cryoneurolysis (Cryo-S, Metrum Cryoflex, Blizne Laszczynskiego, Poland) is performed unilaterally along a treatment line, the location of which was guided by visualization and palpation of anatomic landmarks. The ISN treatment line is located along the line that connects a point located 5 cm medial to the lower pole of the patella and a point located 5 cm medial to the tibial tubercle. The AFCN treatment line is located at one-third the length of the distance from the center of the patella to the top of the femur, with a width equal to the width of the patella.
Sham
Procedure/SurgeryThe exact same procedure as in the cryo-group is performed, except that the nerves are not frozen with the cryoneurolysis apparatus. Sound effects from the machine are replicated to give the patient the same experience as in the active intervention group.
Cumulated pain during walking days 2-7
Cumulated pain (VAS 0-100 mm) upon ambulation in a 5-meter walk test on days 2-7 postoperatively after surgery.
Pain at follow-ups
Pain (VAS 0-100) during rest and during 5-meter walk test at the 2 weeks, 4 weeks, 12 weeks, and 24 weeks follow-up
Pain relief after block
Pain relief immediately following blockade evaluated as ΔVAS 0-100 during a 5-meter walk test before and after the blockade
Cumulated pain during rest and night days 2-7
Cumulated pain at rest and during night from days 2-7
Quality of sleep
Quality of sleep assessed by the patient on a scale of 0-10 from postoperative days 2-7
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Copenhagen University Hospital, Hvidovre
Lead sponsor
Rigshospitalet, Denmark
Collaborator
