Here is the design of a clinical trial:

Official Title: Novel Transcatheter Arterial Embolization for Treatment of Knee Osteoarthritis: a Randomized Sham-controlled Clinical Trial

Included conditions:
- Osteoarthritis, Knee

Study Armgroups:
- {'label': 'Embolization group', 'type': 'EXPERIMENTAL', 'description': 'Group undergoes transcatheter arterial embolization of neovessels around the knee.', 'interventionNames': ['Procedure: Embolization']}
- {'label': 'Sham Embolization Group', 'type': 'SHAM_COMPARATOR', 'description': 'Group undergoes sham embolization', 'interventionNames': ['Procedure: Sham embolization']}

Interventions:
- {'type': 'PROCEDURE', 'name': 'Embolization', 'description': 'transcatheter arterial embolization of neovessels around the knee', 'armGroupLabels': ['Embolization group']}
- {'type': 'PROCEDURE', 'name': 'Sham embolization', 'description': 'Sham transcatheter arterial embolization of neovessels in the knee', 'armGroupLabels': ['Sham Embolization Group']}

Primary Outcomes:
- {'measure': 'KOOS pain sub score', 'description': 'KOOS pain sub score after 4 months', 'timeFrame': '4 months'}

Please estimate the sample size based on the assumption: 
Standard deviation of 16 for the KOOS pain score, significance level (alpha) of 0.05, power (beta) of 0.80, and an estimated 20% dropout rate.
Sample size calculation
        Calculations are partly based on the previous observational studies by Okuno et al. [6, 7]. Despite a possible placebo effect, which account for effect sizes up to 0.5 [21], they found effect sizes of >â5. For our study, we assumed we would require to demonstrate a large effect size of >â0.8 (strong effect) compared to sham embolization since GAE still is (minimally) invasive. Assuming this projected effect size of 0.8, and a standard deviation of 16 for the KOOS (100-0) pain score (estimated from multiple OA studies at Erasmus MC), beta of 0.80, and alpha of 0.05, 48 patients (n = 24 per study arm) are required to detect an increase (higher scores indicate less pain) in primary outcome measure of 8 points in the control group (placebo effect) compared to 21 points in the intervention group. The targeted sample size will be 58 to account for approximately 20% of patients lost to follow-up. We also expect a more homogeneous study population since all included subjects have an NRS pain score â¥ 4 and â¤ 8. With this sample size, and in case of lower variation in pain scores than SD of 16, we expect we could also detect smaller effect sizes between 0.5 (moderate effect) and 0.8.