The goal of this clinical trial is to test the use of a cold and compression brace during the first 6 weeks after surgery in patients who had a total or partial knee replacement.

The main question[s] it aims to answer are:

• What is the effect of the use of cryo- and compression therapy during the first 6 postoperative weeks after knee replacement surgery on pain in rest?
• What is the effect of the use of cryo- and compression therapy during the first 6 postoperative weeks after knee replacement surgery on pain while loading, opioid use, functioning, patient satisfaction and general health, and do participants comply with the therapy?

Participants will be asked to use the cold and compression brace during the six weeks after surgery five times a day, for a maximum of 20 minutes. Researchers will compare with usual care to see the effect on pain, opioid use, functioning, satisfaction and general health.

Total and unicompartmental knee arthroplasty (TKA/UKA) is a widely accepted and effective treatment option for end-stage osteoarthritis (OA) of the knee. Significant long-term improvement in pain, function and quality of life after TKA are reported in literature, yet rehabilitation in the first three months remains challenging. Pain and swelling due to inflammatory reaction after tissue damage may obstruct effective rehabilitation in the early postoperative period. This could result in stiffness of the knee and patient dissatisfaction, also in the long-term. Despite encouraging results after implementing rapid recovery protocols with perioperative local infiltration analgesia and early mobilisation, treatment could still be optimised. Negative side effects (e.g., nausea, vomiting, dizziness) and the increasing abuse of opioid analgesics in modern society drives the search for alternative analgesic techniques. Cryotherapy could play a role in optimising rehabilitation after surgery. Cryotherapy involves the application of cold to the skin surrounding injured soft tissue. Application of cold reduces local blood flow due to vasoconstriction and ensuing the local inflammatory reaction, swelling and heat experience.

The effectiveness of cryotherapy on the recovery after surgery was studied in numerous studies and in the majority - but not in all - of these studies a beneficial effect of the cold therapy was found. Adie et al (2010) show in a systematic review and meta-analysis based on 11 RCT's that using cryotherapy the blood loss is significant lower and the range of motion is higher at discharge. In addition, a small effect on pain is found, cryotherapy leads to lower levels of pain at day 2. This effect was not found at day 1 and 3. No differences were found in complications, analgesics use, length of stay and swelling. Functioning was only measured in one study, so no conclusions could be drawn about that variable. These authors concluded that using cryotherapy postoperatively after a TKA might have benefits, but that the clinical relevance was uncertain. A more recent review performed by Ni et al (2015) confirmed, based on 12 studies, the beneficial results concerning blood loss and pain reduction on day 2. Also, no complications were documented related to the cryotherapy.

Sadoghi et al. (2018) focused on the effects of cryotherapy starting in the first postoperative week and found significant beneficial effects on pain on day 2 and knee flexion on day 6. They did not evidence significant effects in use of analgesics. By contrast, Thijs et al. (2019) found that patients in the cryotherapy group used 2.6 times less opioids as an escape medication during the first four postoperative days compared to the control group. Despite a significant reduction in NRS pain scores before and after cooling in the cryotherapy group, no clear differences on pain between the two groups in the first postoperative week were found. In the long-term too - 2, 6 and 12 weeks postoperatively - no differences could be evidenced. Our recently published RCT has shown that computer-assisted cryotherapy during the first postoperative week following TKA has beneficial in terms of pain reduction and diminished opioid consumption during this first week. At 6 weeks no differences in pain were found. Also the physical examination tests - aROM, knee circumference and Timed Up and Go - showed no difference between groups after 6 weeks. A period of only one week cooling postoperatively can be a reason for short term beneficial effect of the cryotherapy. To our knowledge, no study has been conducted on the effects of 6 weeks cryo and compression therapy after a TKA and UKA.

There are several ways to apply cryotherapy, using ice or cold packs, or mechanical devices which create a standardized cooling treatment of the injured tissue, with and without compression. A review of the currently available literature in TKA and UKA patients stated that standardized continuous cold flow with compression was associated with better outcomes. However, since the financial aspect is also a major element in patient care, cost-effectiveness must be considered as well. Cost benefit analyses demonstrated that simpler devices as ice bag compression bandages or cold packs are far less costly, with no disadvantage in outcomes in several studies. This makes that in the current study an easy-to-use brace with an inserted cold pack, that can be applied with a close fit to the knee, with optional application of manual compression will be used. The combination of cold and compression was suggested to result in longer and improved anaesthetic effect after application.

Primary objective:

Investigating the effect of the use of cryo- and compression therapy during the first 6 postoperative weeks after surgery (TKA en UKA) on pain in rest.

Secondary objective:

Investigating the effect of the use of cryo- and compression therapy during the first 6 postoperative weeks after TKA/UKA surgery on pain while loading, opioid use, functioning, self-perceived change in pain, patient satisfaction and general health. Also the compliance with the cold- and compression therapy will be investigated.

Inclusion Criteria:

• Patients scheduled for a primary TKA or UKA in the Martini Hospital.
• Age ≥ 18 years

Exclusion Criteria:

• per-operative switch from UKA to TKA (only applicable for the UKA patients),
• revision TKA implant (only applicable for the TKA patients),
• rheumatoid arthritis,
• other co-morbidities on which cooling may have a negative effect on (based on judgement of the orthopaedic surgeon),
• inability to read and understand the Dutch language.

Because the cool pack needs to be cooled in a freezer, it is required that a patient or the nursing home has a freezer that can be used.

Only deidentified data will be available upon reasonable written request in conjunction with appropriate data use agreement.

During the baseline visit the preoperative questionnaires will be obtained from the patient and the physical examination tests will be performed. Only after this is finished, at the end of this visit, the randomisation will be performed by opening a sealed envelope.

All patients will be invited for a study control visit after 6 weeks. During the appointment a blinded assessor (not one of the researchers involved in the baseline measurements) will first perform the physical examination tests, after which a check of the completeness of the questionnaires will be done. Finally, the log will be checked. Patients are instructed not to talk about the intervention they received until the log was checked. In this way the preceding measurements can be performed blinded.