Here is the design of a clinical trial:

Official Title: Limited-efficacy Testing of Spring Distraction System (SDS) and a Bilateral One Way Rod (NEMOST) for Early Onset Neuromuscular Scoliosis (BiPOWR)

Included conditions:
- Neuromuscular Scoliosis
- Distraction System
- Growth Friendly System

Study Armgroups:
- {'label': 'Spring Distraction System (SDS)', 'type': 'EXPERIMENTAL', 'description': 'The SDS will be placed and fits around a standard rod of 5.5mm.', 'interventionNames': ['Device: SDS']}
- {'label': 'Necker Enfants Malade OSTeosynthesis (NEMOST)', 'type': 'EXPERIMENTAL', 'description': 'The NEMOST is a one-way-rod that uses a ratchet type of locking mechanism. Both NEMOST devices should be placed in parallel, on the two fixator rods that are connected with a cross connector', 'interventionNames': ['Device: NEMOST']}

Interventions:
- {'type': 'DEVICE', 'name': 'SDS', 'description': 'The patient is implanted with SDS.', 'armGroupLabels': ['Spring Distraction System (SDS)']}
- {'type': 'DEVICE', 'name': 'NEMOST', 'description': 'The patient is implanted with NEMOST.', 'armGroupLabels': ['Necker Enfants Malade OSTeosynthesis (NEMOST)']}

Primary Outcomes:
- {'measure': 'Limited-efficacy of SDS and NEMOST in terms of curve correction maintenance', 'description': 'Changes in cobb angle on radiographs post-op and at 4 weeks, 3 months, 6 months and 12 months follow-up (FU). A maximum of 5 degrees increase will be the threshold to define maintenance.', 'timeFrame': 'Until 1 year post-operatively'}
- {'measure': 'Incidence of possible Treatment-Emergent Serious Adverse Events of SDS and NEMOST', 'description': 'Reported treatment related Serious Adverse Events (SAEs) per-operatively and at 4 weeks, 3 months, 6 months and 12 months FU.', 'timeFrame': 'Until 1 year post-operatively'}

Please estimate the sample size based on the assumption: 
Power (1-β) of 0.8, α = 0.05, SD = 5.1°. Statistical significance set at p < 0.05. Repeated measures ANOVA will be used, with age and sex as covariates. If assumptions for ANOVA are not met, repeated measurement multilevel modelling will be used. Kaplan–Meier survival analysis and Log-Rank test will be used for survival curves. Multiple imputation for missing EOSQ-24 item scores.
Sample size calculation and statistical methods
        The sample size calculation is based on potential differences between groups in maintenance of the coronal curve between the post-operative situation and 1-year follow-up. A difference in Cobb angleââ¥â5Ë is considered clinically relevant and can be reliably measured [27]. In our previous MCGR cohort studies, we found a change in Cobb angle between post-operatively and 1Â year follow-up of 1Ë (SD 5.1Ë) [28]. To determine differences in curve maintenance between groupsââ¥â5Ë with a power (1-Î²) of 0.8, Î±â=â0.05, and SDâ=â5.1Ë, we calculated a sample size of nâ=â28, with a repeated measures ANOVA between factors design (comparing 2 timepoints). With an allocation ratio of 1:1, this means that 14 patients have to be included in each experimental group.
        If all assumptions for performing repeated measures ANOVA are met, both systems will be compared with respect to coronal curve maintenance; age and sex will be included as covariates. For the other continuous variables, repeated measures ANOVA will be used, with the same covariates, but including all evaluated time points. If the assumptions for performing repeated measures ANOVA are not met (e.g. due to missing data), repeated measurement multilevel modelling will instead be performed, with patient, age, sex and treatment group as level 2 variables, and follow-up time as aÂ level 1 variable.
        A KaplanâMeier survival analysis will be performed comparing both groups. The survival curves showing SAE-free survival of both groups will be statistically compared with the Log-Rank test. Analysis of EOSQ-24 scores will be performed using repeated measures ANOVA. In case there are missing EOSQ-24 item scores or questionnaires, multiple imputation with parcel summary scores will be performed using a previously published statistical method [29]. For all statistical tests, statistical significance will be set at pâ<â0.05. All statistical analyses will be performed in IBM SPSS statistics v.26.0.0.1 (Chicago, USA).