This review addressed a clear question in terms of participants, interventions and study design. It did not address comparison groups or predefine outcomes; this may have led to subjective decisions regarding inclusion. Relevant databases were searched and search terms were reported. It appeared that no attempts were made to identify unpublished studies. It was unclear whether language limitations were applied. Publication bias was not considered in the report. Suitable methods to minimise risk of reviewer error and bias were reported for data extraction and validity assessment, but not for study selection. The decision to present included studies narratively and not to pool studies in a meta-analysis was appropriate given the heterogeneity between studies.
It was unclear which trials were used to draw conclusions; the authors reported that four trials were included, but the discussion reported narrative results for six trials and included two that were considered poor quality and not included in the data extraction process. The authors stated that trials were required to report an objective measurement of alignment; only two of the four included studies reported any outcomes.
The authors recognised some of the limitations of the review (particularly in terms of validity assessment) and the poor reporting and average quality of included studies. Despite the methodological deficiencies the conclusions appear to reflect the evidence presented.