Here is the design of a clinical trial:

Official Title: Effects of Infrapatellar Fat Pad Preservation Versus Resection on Clinical Outcomes After Total Knee Arthroplasty in Patients With Knee Osteoarthritis - A Multicenter Randomized Controlled Clinical Trial

Included conditions:
- Knee Osteoarthritis
- Arthropathy of Knee

Study Armgroups:
- {'label': 'Infrapatellar Fat Pad Preservation', 'type': 'EXPERIMENTAL', 'description': 'The IPFP retention of more than 80% in actual operation shall be regarded as IPFP retention.', 'interventionNames': ['Procedure: Infrapatellar Fat Pad preservation']}
- {'label': 'Infrapatellar Fat Pad Resection', 'type': 'ACTIVE_COMPARATOR', 'description': 'In the clinical practice, more than 80% of IPFP volume is commonly resected by surgeons during total knee arthroplasty. The investigators hereby define resection of more than 80% IPFP volume as IPFP excision.', 'interventionNames': ['Procedure: Infrapatellar Fat Pad resection']}

Interventions:
- {'type': 'PROCEDURE', 'name': 'Infrapatellar Fat Pad preservation', 'description': 'In the IPFP preservation group, IPFP (more than 80%) will be preserved by retracting out of the operative field.', 'armGroupLabels': ['Infrapatellar Fat Pad Preservation'], 'otherNames': ['Infrapatellar fat pad retention']}
- {'type': 'PROCEDURE', 'name': 'Infrapatellar Fat Pad resection', 'description': 'In the IPFP resection group, more than 80% IPFP will be resected during the total knee arthroplasty.', 'armGroupLabels': ['Infrapatellar Fat Pad Resection']}

Primary Outcomes:
- {'measure': 'The total score of Knee Injury and Osteoarthritis Outcome Score(KOOS)', 'description': 'The KOOS is a knee-specific patient-reported questionnaire with 42-items in five separately analysed subscales of pain, other symptoms, function in daily living, function in sport and recreation, and knee-related quality of life. Scores are transformed to a 0-100 scale, with 0 representing extreme knee problems and 100 representing no problems.', 'timeFrame': 'From pre-operation to 12 months after operation'}
- {'measure': 'The functional subscale score of Knee Injury and Osteoarthritis Outcome Score(KOOS)', 'description': 'KOOS functional subscale score including function in daily living and function in sport and recreation. Scores range from 0 (worst) to 100 (best).', 'timeFrame': 'From pre-operation to 12 months after operation'}

Please estimate the sample size based on the assumption: 
Significance level (α) of 0.05, power (β) of 0.80, and a 10% dropout rate.
Sample size calculation
        Sample size and power calculation was based on the primary endpoints of KOOS daily activity function score and total score in the mean change from baseline to 12 months. All sample size calculations assume Î±=0.05 and Î²=0.20âand are performed using formulae provided by Cohen.36
        Based on the data collected in previous study,37 38 a between-subject SD of 14 on KOOS daily activity function score will be used and at least 15% improvement would be detected.39 40 To obtain a power of 80% at a significant level of Î±=0.05, a total of 48 participants per group are needed. Assuming a 10% drop out rate, we will need to enrol approximately 54 participants per group to complete the study.
        Sample size calculation is also performed based on another primary outcome total KOOS score with a between-subject SD of 17,41 and eight points difference between groups would be detected according to the literature.42 A total of 82 participants per group are needed to obtain 80% power to detect a significant group effect using an Î± level of 0.05. Assuming a 10% drop out rate, 90 participants are needed in each group.
        Take into consideration of these two calculations, 90 participants in each arm will be sufficient to detect the differences of primary outcomes between groups. Because stratified analyses will be performed to compare clinical outcomes after IPFP preservation versus resection in patients with normal as well as abnormal IPFP qualities, in total 360 participants are needed.