Here is the design of a clinical trial:

Official Title: The Effect of Alendronate Sodium Vitamin D3 Tablets on Knee Joint Structure and Knee Osteoarthritis Pain: A Multi-center, Randomized, Double-blind, Controlled Study.

Included conditions:
- Knee Osteoarthritis

Study Armgroups:
- {'label': 'alendronate sodium vitamin D3 tablets', 'type': 'EXPERIMENTAL', 'description': 'participants will receive alendronate sodium vitamin D3 tablets once per week for one year.', 'interventionNames': ['Drug: alendronate sodium vitamin D3 tablets']}
- {'label': 'placebo', 'type': 'PLACEBO_COMPARATOR', 'description': 'participants will receive a placebo tablet once per week for one year.', 'interventionNames': ['Drug: Placebo']}

Interventions:
- {'type': 'DRUG', 'name': 'alendronate sodium vitamin D3 tablets', 'description': 'once per week for one year', 'armGroupLabels': ['alendronate sodium vitamin D3 tablets']}
- {'type': 'DRUG', 'name': 'Placebo', 'description': 'once per week for one year', 'armGroupLabels': ['placebo']}

Primary Outcomes:
- {'measure': 'WORMS score of knee joint MRI', 'description': 'WORM score of participants at the sixth month after enrollment', 'timeFrame': 'The sixth month'}
- {'measure': 'WORMS score of knee joint MRI', 'description': 'WORM score of participants at the 12th month after enrollment', 'timeFrame': 'The 12th month'}

Please estimate the sample size based on the assumption: 
Power level of 80%, alpha level of 0.05, and an anticipated 10% loss to follow-up each year.
Sample size calculation
        Based on a previous observation, the mean annual loss of the medial tibial cartilage volumes in knee OA patients is 4.5% [25]. The monthly intake of vitamin D (50,000Â IU) would result in a serum vitamin D3 levelâ>â60Â nmol/L [26], and this, in turn, has been reported to correlate with a 2.2% annual absolute reduction in cartilage loss [27]. This can be translated into a risk reduction of 22% for knee replacement over a period of 2Â years [28]. Our sample size calculation was conducted based on Cohenâs formula [29]. With a power level of 80% and alpha level of 0.05, 60 participants (30 in each group) were required to detect a 2.2% between-group difference in terms of medial tibial cartilage loss (WORMS scale) during the second assessment time-point (12Â months). Losses to follow-up were not considered in our initial sample size calculation (NCT04739592); however, given the fact that both interventions will be administered for a year and patients will be followed up for 2Â years after enrollment, we anticipate that around 10% will be lost to follow-up each year, so we increased our final sample size to 220 participants (110 in each group).