Level of Evidence
Four studies were rated with evidence levels of low;8,21-23 seven studies with moderate,24-30 and three studies with high (Tables 1,2).31-33 In terms of lack of methodologyrigor, institutional review board approval was not reported in three of the studies.21,26,29 Power calculations for sample size were not reported in 10 of the studies.8,21-26,28-30 Randomization procedures were not used in 12 studies.8,21-30,32 Six studies had sample sizes of less than 50 participants.8,22,23,27-30 Two studies were limited by selection bias (convenience sampling),21,31 and two studies used outcome measures without discussion of validity.26,29 Consistency was evident in seven studies where reproducibility of measures and interventions was reported.8,22,25,27,31-33 Directness prompts for an evaluation of similarities between comparison groups and was discussed in comparison studies of different types of kyphosis21,22,24,25 and in one study in which there was an unequal population comparison due to a predominance of females.28 Effect size was most certain in the three studies that rated as high level of evidence due to power analysis, adequate sample size, narrow confidence intervals, or large effect size.31-33 Importantly, all 3 studies with a high level of evidence were identified in the Biologic Perspective search (Table 1).