Background: After total knee arthroplasty (TKA), patients can be discharged from hospital as early as two days after surgery. However, patients often do not achieve functional knee flexion range of motion (ROM) in the first postoperative days. Early application of hyperbaric gaseous cryotherapy (HGC) at the operated knee within an hour after surgery and the next postoperative days might increase ROM by reducing inflammation, edema and pain. However, it is unclear whether such early application of HGC is feasible. Moreover, there is no data to allow calculation of the sample size required to conduct a randomized controlled trial to compare the effects of HGC to those of conventional cryotherapy on the increase of knee flexion in the first two days after TKA.~Objectives: To investigate the feasibility of applying HGC within an hour after TKA and twice a day the next postoperative days. To collect data on changes in knee flexion ROM in the first two postoperative days to calculate the sample size required for a large randomized controlled trial. To compare the effects of HGC to those of conventional cryotherapy on changes in knee flexion ROM in the first two postoperative days.~Design: A prospective, single-blinded, randomized, controlled pilot trial.~Setting: Orthopedic postoperative unit in an acute care hospital.~Interventions: Patients were randomly allocated to either hyperbaric gaseous cryotherapy (intervention group) or the ice bag cryotherapy (control group). In each group, participants received the specific cryotherapy intervention at the operated knee within an hour after the surgery (day 0) and twice the next two postoperative days (day 1 and day 2).~Outcome measures: Feasibility measures included the rate of eligible patients who were willing to participate, attrition, adherence to interventions and presence of adverse effects. Active and passive knee flexion range of motion (ROM) and knee pain intensity at rest were evaluated on postoperative days 1 and 2. Change in active and passive knee flexion ROM and in knee pain intensity at rest from postoperative day 1 to day 2 were assessed. Length of hospital stay was collected.
A pilot study was performed to investigate the feasibility of a large randomized controlled trial (RCT) to assess the effects of hyperbaric gaseous cryotherapy (HGC) on the change in knee flexion range of motion in the first two days after total knee arthroplasty.