The reliability and measurement error of protractor-based goniometry of the fingers: A systematic review

STUDY DESIGN: Systematic review PURPOSE OF THE STUDY: The purpose was to review the available literature for evidence on the reliability and measurement error of protractor-based goniometry assessment of the finger joints. METHODS: Databases were searched for articles with key words "hand," "goniometry," "reliability," and derivatives of these terms. Assessment of the methodological quality was carried out using the Consensus-Based Standards for the Selection of Health Measurement Instruments checklist. Two independent reviewers performed a best evidence synthesis based on criteria proposed by Terwee et al (2007). RESULTS: Fifteen articles were included. One article was of fair methodological quality, and 14 articles were of poor methodological quality. An acceptable level for reliability (intraclass correlation coefficient > 0.70 or Pearson's correlation > 0.80) was reported in 1 study of fair methodological quality and in 8 articles of low methodological quality. Because the minimal important change was not calculated in the articles, there was an unknown level of evidence for the measurement error. DISCUSSION: Further research with adequate sample sizes should focus on reference outcomes for different patient groups. For valid therapy evaluation, it is important to know if the change in range of motion reflects a real change of the patient or if this is due to the measurement error of the goniometer. Until now, there is insufficient evidence to establish this cut-off point (the smallest detectable change). CONCLUSION: Following the Consensus-Based Standards for the Selection of Health Measurement Instruments criteria, there was limited level of evidence for an acceptable reliability in the dorsal measurement method and unknown level of evidence for the measurement error. LEVEL OF EVIDENCE: 2a