Here is the design of a clinical trial:

Official Title: Effectiveness and Safety of Early Intramuscular Botulinum Toxin Injections to Prevent Shoulder Deformity in Babies With Obstetrical Brachial Plexus Palsy

Included conditions:
- Obstetrical Brachial Plexus Palsy

Study Armgroups:
- {'label': 'Toxin group', 'type': 'EXPERIMENTAL', 'description': 'The babies receive a botulinum toxin type A injection at the age of 12 months', 'interventionNames': ['Drug: Botulinum toxin type A injection']}
- {'label': 'Sham group', 'type': 'SHAM_COMPARATOR', 'description': 'The babies receive a simulated injection procedure at the age of 12 months', 'interventionNames': ['Other: Sham']}

Interventions:
- {'type': 'DRUG', 'name': 'Botulinum toxin type A injection', 'description': 'A total of 8UI/kg will be injected in the internal shoulder rotator muscles: 2UI/kg in the sub scapular muscle, 3UI/kg in the pectoralis major muscle and 3UI/kg in the teres major/latissimus dorsi muscle.', 'armGroupLabels': ['Toxin group']}
- {'type': 'OTHER', 'name': 'Sham', 'description': 'The injection is mimed, the procedure is the same as the botulinum toxin injection.', 'armGroupLabels': ['Sham group']}

Primary Outcomes:
- {'measure': 'Change in the percentage posterior migration of the humeral head measured on axial MRI slices between 11 (before the BTI carried out at 12 months) and 18 months of age (6 months post BTI).', 'timeFrame': 'At 18 month age'}

Please estimate the sample size based on the assumption: 
In order to guarantee a power of 90%, a sample of 22 babies per group is required. To account for babies lost to follow-up (10%) and babies who will not be treated because of a lack of true subluxation on MRI, 62 babies will be recruited. P<0.05 will be considered as statistically significant.
Sample size and statistical analysis
        No longitudinal data regarding the progression of bony deformities in children with BPBI are available in the literature. Only transversal studies have been carried out, indicating that posterior subluxation is significantly greater on the affected side compared with the healthy side at the age of 4.8 months (affected side 32.1%â: SD=19.7%âvs healthy side 49.8%: SD=7.3%).6 The calculation of the number of subjects necessary for this study was based on a difference of the standard deviation at 12 months, for a SD of 5%.
        In order to guarantee a power of 90%, a sample of 22 babies per group is required, thus a total of 44. In order to account for babies lost to follow-up (10%) and babies who will not be treated because of a lack of true subluxation on MRI, 62 babies will be recruited.
        The characteristics of the babies in both groups will be described using means, SD, medians, quartiles or frequencies. Mean changes in 2D percentage humeral subluxation, 3D humeral subluxation, 2D and 3D glenoid version, the AMS score and passive shoulder ROM will be compared using analysis of covariance (ANCOVA) adjusted on the initial values. If the hypotheses underlying the ANCOVA model are not respected, a non-parametric Wilcoxon test will be used. Shoulder muscle volumes and the mini-AHA scores will be compared between the groups using a Studentâs t-test or a non-parametric Mann-Whitney test, depending on the distribution of the variable of interest. Lastly, the number of serious and non-serious adverse events, and the degree of fibrosis and fatty infiltration will be compared between the two groups using a Ï2 test or Fisherâs exact test, so as the number of secondary surgeries. P<0.05âwill be considered as statistically significant.
        Data analysis will be carried out on an intention to treat basis by a biostatistician after blind review and database freezing at the end of the study. No intermediate analysis is planned during this trial.