Arthroscopic surgery is a recently developed minimally invasive surgery in China. In addition to treating knee joint problem, arthroscopy can also be used for the diagnosis and treatment of shoulder disease, which has the advantages of small incision, precision procedure, intuition, etc. However, local pain and swelling are still common postoperative problems. Periarticular ice therapy after surgery can promote microvascular contraction, slow down nerve conduction velocity and paralyze local peripheral nerve, which plays the roles in hemostasis, pain relief and detumescence. It can also reduce patient's dependence on analgesics and promote wound healing. Conventional cold therapy with ice pack has certain curative effects on postoperative swelling and pain relief, but it has limitations such as high hardness, poor fit with skin, inconvenient fixation, less contact with body surface, etc. Recently, our department has applied a new type of cold therapy device to perform analgesia on the patient with shoulder joint surgery and has achieved good postoperative analgesia effect.

1．Research objects: This study included the patients with shoulder disease who received shoulder arthroplasty at Peking University People's Hospital from January 2016 to April 2017. The same screening criteria was used for the inclusion and exclusion of the cases to avoid the influence of different factors on statistical results to the most extent. Inclusive criteria: (1) Patients who received shoulder arthroscopy for various shoulder diseases including rotator cuff tear, shoulder impingement syndrome, frozen shoulder and calcific tendinitis of supraspinatus without gender preference; (2) Patients who cooperated to complete pain assessment with clear consciousness and no communication barrier; (3) Patients who received postoperative analgesia with pressure cold therapy device or disposable ice pack. Exclusive criteria: (1) Combination of severe cardiovascular disease, anemia, hypoproteinemia, diabetes and other factors that affect healing; (2) Combination of vascular spasmodic diseases such as thrombotic arteritis; (3) Patients with hypothermia sensitivity, poor local circulation or hypaesthesia; (4) Patients who could not comply with treatment; (5) Patients with the infection of other parts. 60 patients (15 males and 45 females) satisfied the inclusive criteria, and the age ranged from 41 to 80 years with an average age of (61.85±9.54) years. Both the intervention group (using pressure cold therapy) and the control group (using disposable ice pack) comprised 30 cases each. There were 9 males and 21 females in the intervention group, and the average age was (61.83±8.78) years. There were 6 males and 24 females in the control group, and the average age was (61.86±10.39) years. There was no statistical difference of age and gender between the two groups (P=0.546 and P=0.08) . 2. Treatment methods: (1) Patients in the intervention group received postoperative orthopedic care, 50 mg of flurbiprofen axetil and q12 h of intravenous infusion. Meanwhile, the pressure cold therapy device was used for cold therapy during concentrated compression. The therapy was conducted 3 sessions per day at 8:00, 12:00 and 16:00 respectively. The cold therapy was carried out for 3 consecutive days, and each session continued for 20 mins. The pressure cold device was equipped with ice bucket and ice sac. The ice sac was placed on the surface of the affected part and was connected with cooler conduit, and the cooler was raised for 38 cm. The exhaust valve was opened to pressurize ice-water mixture into the ice sac. As the pressure was appropriate, the conduit was disconnected with the ice sac to start treatment. (2) Patients in the control group received postoperative orthopedic care, 50 mg of flurbiprofen axetil and q12h of intravenous infusion. Meanwhile, the patient was given disposable self-cooling ice pack for cold therapy. The ice pack was consisted of water crystal sodium carbonate and ammonia nitrate, and the ingredients were separated by clip. As the transverse clip was pulled out, the two ingredients were mixed together. The ice pack wrapped in small towel was applied on the affected shoulder. 2 packs were placed above shoulder, and 1 pack was placed below shoulder. This therapy was conducted 3 sessions per day at 8:00, 12:00 and 16:00 respectively. The therapy was carried out for 3 consecutive days, and each session continued for 20 mins. To prevent the wound dressing from the moisture of ice pack, the disposable ice pack was wrapped with single-layer towel. To keep the cold therapy under correct temperature, the towel should not be too thick. 3. Evaluative methods: The pain levels of postoperative 24, 48 and 72 hours were observed and recorded using visual analogue scale (VAS) : a line of 10 cm was drawn on the paper with one end of 0 indicating no pain and the other end of 10 indicating the worst pain; the middle part indicated different degrees of pain. The commonly used criteria for clinical evaluation are 0 for painlessness, 1 to 3 for mild pain, 4 to 6 for moderate pain, 7 to 9 for severe pain and 10 for severe or breakthrough pain. The scaled side of the ruler was turned back to the patient, and the patient was asked to mark the scale depending on this pain. The corresponding scale (resting pain/active pain) was recorded by nurse. 4. Statistical analysis: SPSS 17.0 software was used for statistical analysis. The measurement data were presented as mean±standard deviation. Two samples were compared using independent sample t test. A P value < 0.05 was regarded as statistically significant.

The shoulder pain of all patients was evaluated by VAS before operation. The mean VAS score of resting pain for the intervention group was (0.93±0.70) points, and the mean VAS score of active pain was (2.13±0.78) points. The mean VAS score of resting pain for the control group was (0.93±0.69) points, and the mean VAS score of active pain was (2.13±0.77) points. There was no significant statistical difference in the preoperative shoulder rest pain and active pain scores between the two groups (P=1.000) . The mean operation time of 60 patients was (65.5±18.47) mins. The mean operation times of the intervention group and control group were (62.17±15.96) mins and (68.83±20.41) mins respectively. There was no significant difference between the two groups (P=0.189) . There were significant differences in resting pain index between the intervention group and control group 24, 48 and 72 hours after operation (P_24h=0.005, P_48h=0.002, P_72h=0.000) . There was no statistical difference in active pain index between the two groups 24 hours after operation (P_24h=0.057) . There were statistical differences in active pain index between the two groups 48 and 72 hours after operation. (P_48h=0.015, P_72h=0.000) .

The application of pressure cold therapy after shoulder arthroscopy can effectively alleviate the pain around shoulder, which is beneficial to the early recovery of functional exercise and the promotion of shoulder function recovery. The utility model has the advantages of convenient fixation and easy nursing with great clinical application value.