Here is the design of a clinical trial:

Official Title: Cryoneurolysis Outcome on Pain Experience (COPE) in Patients With Low-back Pain - a Single-blinded Randomized Controlled Trial

Included conditions:
- Chronic Low-back Pain
- Facet Joint Pain
- Degeneration Lumbar Spine
- Facet Joint Syndrome
- Back Pain Lower Back Chronic

Study Armgroups:
- {'label': 'Cryoneurolysis', 'type': 'ACTIVE_COMPARATOR', 'description': '40 patients are randomized to receive one treatment of cryoneurolysis on the facet joints of three lumbar level corresponding to their facet joint pain generator', 'interventionNames': ['Procedure: Cryoneurolysis']}
- {'label': 'Radiofrequency ablation', 'type': 'ACTIVE_COMPARATOR', 'description': '40 patients are randomized to receive one treatment of radiofrequency ablation on the facet joints of three lumbar level corresponding to their facet joint pain generator', 'interventionNames': ['Procedure: Radiofrequency ablation']}
- {'label': 'Placebo', 'type': 'SHAM_COMPARATOR', 'description': '40 patients are randomized to receive sham treatment. Subjected to similar procedures as cryoneurolysis and radiofrequency ablation, but without active treatment.', 'interventionNames': ['Procedure: Placebo']}

Interventions:
- {'type': 'PROCEDURE', 'name': 'Cryoneurolysis', 'description': 'This is a medical procedure that temporarily blocks nerve conduction along peripheral nerve pathways by freezing it. Small probe is inserted in order to freeze the target nerve, can facilitate complete regeneration of the structure and function of the affected nerve.', 'armGroupLabels': ['Cryoneurolysis'], 'otherNames': ['cryoanalgesia', 'cryoneuroablation']}
- {'type': 'PROCEDURE', 'name': 'Radiofrequency ablation', 'description': 'This is a medical procedure that temporarily blocks nerve conduction along peripheral nerve pathways. Small needle with an active heating tip is inserted, to destroy the functionality of the target nerve using heat from radiofrequency energy.', 'armGroupLabels': ['Radiofrequency ablation']}
- {'type': 'PROCEDURE', 'name': 'Placebo', 'description': 'No active treatment is given.', 'armGroupLabels': ['Placebo']}

Primary Outcomes:
- {'measure': 'The effect of the intervention, assessed by Patient Global Impression of Change (PGIC) at 4 weeks follow-up', 'description': 'The Patient Global Impression of Change (PGIC) is a 7-point patient self-reporting scale of overall improvement after treatment ranging from 1) very much improved, 2) much improved, 3) minimally improved, 4) no change, 5) minimally worse, 6) much worse, or 7) very much worse', 'timeFrame': '4 weeks'}

Please estimate the sample size based on the assumption: 
80% power, two-tailed test, α = 0.025, 25% margin for loss to follow-up, overall significance level of 5%.
Sample Size
        Based on our pilot study (not published), we postulate that 50â% of the participants who receive an active treatment (cryoneurolysis or radiofrequency ablation) and 5â% of the placebo group will report a significant improvement of change in pain after intervention, equivalent to Patient Global Impression of Change (PGIC)ââ¤â2, at 4 weeksâ follow-up. Sample size is calculated by Fisherâs Exact test based on the above-mentioned and with 80â% power (two-tailed) and Î±â=â0.025, 120 participants (40 per group) are needed in the study, which also includes a 25â% margin for loss to follow-up. The power of the study is the probability that there is a significant difference between each of the two intervention groups, where in each of the two tests a significant level of 2.5â% is used, so that the overall significance level becomes 5â%.