Here is the design of a clinical trial:

Official Title: Functional Outcome of Total Knee Replacement. Randomized Clinical Controlled Trial of Novel and Conventional Implants

Included conditions:
- Osteoarthritis, Knee
- Arthroplasty
- Total Knee Replacement

Study Armgroups:
- {'label': 'PFC Total Knee Replacement', 'type': 'ACTIVE_COMPARATOR', 'description': 'PFC, Conventional design Perioperative treatment will be carried out according to routine protocol of the hospital.', 'interventionNames': ['Device: NexGen', 'Device: Persona']}
- {'label': 'NexGen Total Knee Replacement', 'type': 'ACTIVE_COMPARATOR', 'description': 'NexGen, Conventional design Perioperative treatment will be carried out according to routine protocol of the hospital.', 'interventionNames': ['Device: Persona', 'Device: PFC']}
- {'label': 'Persona Total Knee Replacement', 'type': 'ACTIVE_COMPARATOR', 'description': 'Persona, Novel design Perioperative treatment will be carried out according to routine protocol of the hospital.', 'interventionNames': ['Device: NexGen', 'Device: PFC']}

Interventions:
- {'type': 'DEVICE', 'name': 'NexGen', 'description': 'Comparing two conventional designs and one novel design', 'armGroupLabels': ['PFC Total Knee Replacement', 'Persona Total Knee Replacement']}
- {'type': 'DEVICE', 'name': 'Persona', 'description': 'Comparing two conventional designs and one novel design', 'armGroupLabels': ['NexGen Total Knee Replacement', 'PFC Total Knee Replacement']}
- {'type': 'DEVICE', 'name': 'PFC', 'description': 'Comparing two conventional designs and one novel design', 'armGroupLabels': ['NexGen Total Knee Replacement', 'Persona Total Knee Replacement']}

Primary Outcomes:
- {'measure': 'Changes in patient reported outcome measures scores (PROMs), Functional improvement', 'description': 'Oxford Knee Score (OKS)', 'timeFrame': 'preoperative, postoperative at 2-3 months, at 1 year and at 2 years'}

Please estimate the sample size based on the assumption: 
Alpha = 0.05, power = 0.8, 10% drop-out rate, and 10% addition due to skewness in the variable distribution.
Sample size
        The power analyses will be calculated using both the OKS (primary outcome) and the FJS (secondary outcome). Of these, the FJS is more sensitive in differentiating patients at the upper end of the outcome scores and requires larger patient groups. With the OKS, the estimated sample size is 48 patients per arm. With the FJS in the range of 60 to 80 and a standard deviation of 25 points, the estimated sample size is 64 patients per arm (deltaâ=â13, sdâ=â25, alphaâ=â0.05, powerâ=â0.8). Allowing for a 10% drop-out rate and a 10% addition due to skewness in the variable distribution, the required arm size is 80. Therefore, with three comparison arms, the total number of patients recruited into the study will be 240.