Computer-assisted Cryotherapy After Total Knee Arthroplasty

The aim of this study was to investigate whether computer-assisted cryotherapy is effective in reducing postoperative pain and analgesics consumption, next to improving functional outcome and patient satisfaction after total knee arthroplasty (TKA). The hypothesis is that computer-assisted cryotherapy has positive effects on postoperative pain after TKA.

For this purpose a single-centre non-blinded trial was designed where two groups of patients were observed, a cold (cryotherapy) C-group and a regular (control) R-group. Depended on the week they were operated patients received either usual care (R-group) or computed-assesed- cryotherapy (odd or even week; week-on/week-off principle). Patients in the C-group received next to usual postoperative care computer-assisted cryotherapy for several hours a day during the first seven postoperative days (10-12 degrees Celcius).

Primary outcome was pain, monitored with the numerical rating scale for pain. Secondary outcomes were the use of opioid escape medication, function and swelling, monitored by active range of motion, timed up and go test and circumference measurements; several patient-reported outcome measures (short term 2 and 6 weeks; and longer term 6 and 12 months postoperative); and patient satisfaction, monitored by the numerical rating scale for satisfaction.

The study was conducted at the Orthopaedic Surgery Department of Martini Hospital, a teaching hospital in the Netherlands. All participants gave signed informed consent before participation. Patients with end-stage OA over the age of 18 who were scheduled for a TKA were invited to participate in this study. Exclusion criteria were rheumatoid arthritis, skin or other infections, vascular disease, other comorbidities on which cooling may have a negative effect, and strong preference for one of the treatment options. Patients were randomised into one of the two groups by a week-on/week-off principle. Patients who underwent TKA surgery in an even week received additional postoperative cryotherapy (C-group), those who had the surgery in an odd week received usual postoperative care (R-group). Surgery dates were scheduled in the usual way by the planning department of the hospital. Two weeks before surgery, patients were informed by phone as to which group they were assigned to. Both groups received the usual rapid recovery (RR) care and rehabilitation program, consisting of local infiltration analgesia during surgery, compressive bandaging for 24 h after surgery, and full weight-bearing mobilisation and active range of motion exercises starting on the day of surgery. Antibiotics were given preoperatively and postoperatively. All patients received thromboembolic prophylaxis for a period of six weeks. The Smith \& Nephew (Memphis, USA) posterior stabilized (PS) GENESIS II total knee system was used for the TKA.

For the CAC in the C-group, the ZAMAR ZHC-MG665A (ZAMAR, Vrsar, Croatia) was used during hospitalisation and the smaller CAC system ZAMAR ZT Cube (ZAMAR, Vrsar, Croatia) for the home situation. The CAC system was delivered to the patient's home before the day of the surgery. Both models had a touchscreen with pre-set programs, with parameters as shown in the cooling schedule. All patients received a personal cooling brace, the ZAMAR Wrap, which transferred cold onto the skin and deep tissue around the knee. Patients in the C-group were instructed to cool the operated knee during the first seven postoperative days. The schedule they received was based on a schedule used by Thijs et al. Patients were allowed to deviate from this schedule, but were asked to document the actual cooling time and temperature in a log.

Eligibility Criteria:
Inclusion Criteria:

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

Exclusion Criteria:

* skin (or other) infections
* rheumatoid arthritis
* vascular disease
* having a strong preference for one of the two treatment options