The purpose of this study is to analyze the effect of the ERAS(early recovery after surgery) protocol on total knee and hip arthroplasty compared to conventional standard protocol. Patients will be divided into two groups: ERAS protocol group and standard protocol group. On the day before the surgery, the patient group was randomly assigned by the researcher (research nurse) who did not participate in the surgical procedure. By comparing the clinical outcomes and quality of postoperative recovery of both groups, we could confirm the effect of ERAS protocol.

The patients who underwent radiologic examination at Severance Hospital of Severance Hospital and who will received total knee arthroplasty or total hip arthroplasty due to primary degenerative osteoarthritis or osteonecrosis of femoral head. Patients will be divided into two groups: ERAS (early recovery after surgery) protocol group and standard protocol group. On the day before the surgery, the patient group was randomly assigned by the researcher (research nurse) who did not participate in the surgical procedure.

The patients in the ERAS group were given a pre-treatment drug [300 mg (gabapentin) and 10 mg oxycontin (oxycontin) and 2 mg prednisolone (prednisolone 10 mg)] on the evening before surgery. And pre-operative fasting should not exceed 6 hours, and clear liquid fasting should not exceed 2 hours. In addition, 400 ml of oral carbohydrate should be taken 2 to 4 hours before surgery to ensure adequate blood sugar and encourage regular diet (light meal) as soon as possible within a tolerable range after surgery. The initial pain after surgery is actively controlled by oral drugs such as celebrex and IR codon, and injections such as tramadol and demerol. On the first postoperative day, the urinary catheter is removed and CPM (continuous passive motion) rehabilitation is started.

On the other hand, in standard group, there is no medication as a pre-treatment drug. Patients should be fasted for 8 hours in both solid and liquid preoperatively. After the surgery, allow a small amount of clear liquid to remain at the 4-hour fasting period after the operation, and allow the fluid to start within a tolerable range after 4 hours. The urinary catheter is removed on the first postoperative day and CPM rehabilitation is started from the afternoon. Post-operative ambulation should begin as early as possible on the second postoperative day.

All patients will undergo anesthesia for general anesthesia or spinal anesthesia with a nerve block (adductor canal block or femoral nerve block). The quality of recovery index was assessed on the day before surgery and on the POD 1 quality of recovery score (QoR) 40 questionnaire. And the length of hospital stay, first eating time, first assisted walking time, and start of rehabilitation after surgery of all patients will be recorded. The number of times that need antiemetics due to nausea / vomiting during the hospitalization period will be recorded. After discharge from the hospital, the patient will visit outpatient clinic at 4 ± 2 weeks postoperatively and will be checked a physical examination such as the ROM of the knee. At 3 ± 1 months and 6 ± 1 months after surgery, VAS, WOMAC, AKS, knee ROM, and PF score of all patients would be checked in outpatients clinic. In addition, morbidity, complications, mortality, and re-admission before and up to 6 months after surgery would be recorded.

Inclusion Criteria:

• 1. elective total knee arthroplasty for degenerative osteoarthritis
• 2. elective total hip arthroplasty for osteoarthritis of osteonecrosis of femoral head

Exclusion Criteria:

• 1. ASA class >3
• 2. severe medical comorbidities
• 3. inflammatory arthritis including rheumatoid arthritis
• 4. severe instability of knee or hip
• 5. revision surgery