Here is the design of a clinical trial:

Official Title: Randomised Controlled Study Comparing Fast Track and Standard Care Protocol on Functional Outcomes and Hospital Stay Of Total Hip Arthroplasty

Included conditions:
- Hip Osteoarthritis
- Arthropathy of Hip

Study Armgroups:
- {'label': 'Fast Track Protocol', 'type': 'ACTIVE_COMPARATOR', 'description': 'Patients treated using Fast Track Care Protocol', 'interventionNames': ['Procedure: Fast Track Protocol']}
- {'label': 'Standard Protocol', 'type': 'ACTIVE_COMPARATOR', 'description': 'Patients treated using Standard Care Protocol', 'interventionNames': ['Procedure: Standard Care Protocol']}

Interventions:
- {'type': 'PROCEDURE', 'name': 'Fast Track Protocol', 'description': 'Fast Track Care consists in educational preoperative preparation for patients, particular strategies for controlling pain and intensive early rehabilitation protocol', 'armGroupLabels': ['Fast Track Protocol']}
- {'type': 'PROCEDURE', 'name': 'Standard Care Protocol', 'description': 'Standard Care Protocol consists in the same surgical intervention without educational preoperative preparation for patients and intensive early rehabilitation protocol', 'armGroupLabels': ['Standard Protocol']}

Primary Outcomes:
- {'measure': 'Early functional outcomes', 'description': 'Early functional outcomes are collecting using Lowa Level of Assistance(ILOA) during the third post-operative day.\n\nThis scale is able to provide data on the autonomy reached by the patient in the first postoperative period going to investigate five main motor activities (get up from supine to seated, from sitting to standing position, walk around, take three steps, the speed of walking). The total score can vary from 0 to 56, where 56 indicates worst functional results.', 'timeFrame': 'Third post operative day'}

Please estimate the sample size based on the assumption: 
A power of 90%, a significance level of 0.05, and a 10% drop-out rate are assumed.
Sample size calculation, randomization, and statistical analysis
        The sample size was calculated based on the primary outcomeâi.e., score changes in the ILOA scale collected at the third postoperative day. Specifically, considering a standard deviation of the ILOA scale of Â± 6.9, a difference of seven points deemed clinically significant [20, 29], and a power of 90% with a significance level of 0.05, the minimum number of patients to be enrolled is estimated at 40 per arm (1:1 ratio) [43]. Presuming a 10% drop-out rate, following potential rare severe complications during surgery, it is necessary to enroll 90 patients, 45 per arm.
        The subjects are randomized to either the SC group or the FT group by the ER software [44] using the permuted blocks method [45] to randomly allocate the participants to each group in order to avoid imbalance in the number of participant assignment. Randomization, 1:1 ratio for each treatment arm, is performed centrally at the IRCCS Istituto Ortopedico Rizzoli by a colleague who is not involved in subject enrolment and is blinded to the participants, investigators/health care providers, or persons assessing outcomes. The randomization list is inserted in envelopes sequentially numbered and sealed; the investigator opens the envelopes in sequence on the day of enrolment.
        A modified intention-to-treat (mITT) analysis is used to handle data of patients. Specifically, every subject who is randomized to each treatment group, excepted for patients with severe intraoperative complications, ignoring withdrawal, and anything that happens after surgery, is accounted for in the interpretation of results.
        Patients are monitored at third postoperative day, at discharge, and during follow-up fixed at 6 weeks and 3, 6, and 12 months (according to standard clinical practice).
        ILOA, NRS, WOMAC and HHS scores, LOS, the number of postoperative blood transfusions, the need for rescue doses during analgesic therapy and AEs are assessed to compare the two treatment arms. Outcome assessors and analysts are blinded.
        Analyses are performed using GraphPad Prism ver. 6. For the values for which the mean and standard deviation is determined, a 95% confidence coefficient (CI 95%) is also determined, indicating a range of values with a 95% confidence level of a similar group mean. The ILOA difference between groups is calculated using the chi-square criterion method or Fisherâs direct test. A significant difference between groups is considered for P < 0.05. In addition, for the evaluation of secondary outcomes (i.e., scores for the NRS, WOMAC, HHS, LOS, the number of blood transfusion and rescue doses, AEs), a comparison between groups will be performed using the Student t-test if the data will be normally distributed. If not, the Mann-Whitney U test will be used to compare groups at each measurement time. Differences between groups are considered significant for P < 0.05. In case of data collected by primary and secondary outcome measurements will be affected by covariates (e.g., age, gender, BMI, ASA, short/standard stem, or the number of blood transfusions), a post hoc regression analysis will be performed to reduce any bias in the estimation of treatment effect which may occur by a potential random imbalance between groups [46].