Weightbearing and nonweightbearing ankle dorsiflexion range of motion: Are we measuring the same thing?

Background: Ankle dorsiflexion range of motion has been measured in weightbearing and nonweightbearing conditions. The different measurement conditions may contribute to inconsistent conclusions regarding the role of ankle dorsiflexion in several pathologic conditions. The purpose of this study was to examine the relationship between ankle dorsiflexion range of motion as measured in weightbearing and nonweightbearing conditions. Methods: We compared ankle dorsiflexion range of motion as measured in a weightbearing versus a nonweightbearing position in 43 healthy volunteers. Measurements were taken separately by two examiners. Results: Weightbearing and nonweightbearing ankle dorsiflexion measurements produced significantly different results (P<.0001). The two measurements correlated moderately (r=0.6 and r=0.64 for examiners 1 and 2, respectively; P<.001). Conclusions: Weightbearing and nonweightbearing ankle dorsiflexion measurements produce significantly different results and only a moderate correlation, suggesting that these two measurements should not be used interchangeably as measures of ankle dorsiflexion range of motion.