Here is the design of a clinical trial:

Official Title: Duloxetine Combined With Intra-articular Injection of Corticosteroid and Hyaluronic Acid Reduces Pain in the Treatment of Knee Osteoarthritis Patients

Included conditions:
- Osteoarthritis, Knee
- Chronic Pain

Study Armgroups:
- {'label': 'Duloxetine combined with intra-articular injection', 'type': 'EXPERIMENTAL', 'interventionNames': ['Drug: Duloxetine', 'Drug: intra-articular injection of corticosteroid and hyaluronic acid']}
- {'label': 'Intra-articular injection', 'type': 'ACTIVE_COMPARATOR', 'interventionNames': ['Drug: intra-articular injection of corticosteroid and hyaluronic acid']}

Interventions:
- {'type': 'DRUG', 'name': 'Duloxetine', 'description': 'Participants will start on duloxetine 30 mg per day for one week and then titrated up to duloxetine 60mg per day for 23 weeks.', 'armGroupLabels': ['Duloxetine combined with intra-articular injection']}
- {'type': 'DRUG', 'name': 'intra-articular injection of corticosteroid and hyaluronic acid', 'description': 'Participants will receive a 3.5 ml intra-articular injection of 30mg of hyaluronic acid plus 10mg of triamcinolone acetonide.', 'armGroupLabels': ['Duloxetine combined with intra-articular injection', 'Intra-articular injection']}

Primary Outcomes:
- {'measure': 'Weekly mean of the 24h average pain scores', 'description': "Weekly mean of the 24h average pain scores in participants with osteoarthritis knee pain at the end of 24 weeks as reported in participants' diaries based on the 11-point Likert scale (an ordinal scale with 0 indicating 'no pain', and 10 indicating 'worst pain imaginable')", 'timeFrame': 'Twenty-fourth weeks'}

Please estimate the sample size based on the assumption: 
80% power at a two-sided α level of 0.05, with a drop-out rate of 10%.
Sample size calculation
        Based on previous research,31 we estimate that the mean of the weekly mean of the 24âhours average pain scores after 24 weeks will be approximately â2.92Â±1.725 in the experimental group (IA (HA+CS) combined with oral duloxetine) and â2.08Â±1.745 in the control group (IA (HA+CS)). In total, 68 patients per group will be needed to achieve 80% power at a two-sided Î± level of 0.05. Considering a drop-out rate of 10%, in total, 75 patients per arm are needed; thus, in total, 150 patients will be needed for this trial.