Static measurement of tibia vara. Reliability and effect of lower extremity position.

The purpose of this study was to examine the reliability of tibia vara measurements and to determine the effects of lower extremity position on such measurements. A manual goniometer was used to measure tibia vara in both lower extremities of 20 healthy subjects while they assumed three different positions: double-limb stance (DLS) with subtalar joint position uncontrolled (Condition 1), DLS with subtalar joint positioned in neutral (Condition 2), and single-limb stance with subtalar joint position uncontrolled (Condition 3). Intraclass correlation coefficients (p less than .05) revealed that tibia vara measurements were reliable both within and between raters with mean absolute differences between repeated measures of 2 to 3 degrees. An analysis of variance and a Newman-Keuls post-hoc test (p less than .05) showed that Condition 3 produced the greatest value of tibia vara followed by Conditions 1 and 2, respectively. The results of this study suggest that lower extremity position is an important consideration when measuring tibia vara and determining whether treatment intervention is indicated.