Measuring standing hindfoot alignment: reliability of goniometric and visual measurements.

Objective: To examine the reliability of a functional weight-bearing measure of hindfoot alignment, the standing tibiocalcaneal angle (STCA), and to compare the relative reliabilities of goniometrically and visually estimated STCAs.

Design: Prospective blinded comparison.

Setting: Sports medicine center.

Participants: Eighteen asymptomatic volunteer subjects (10 men, 8 women; age range, 22-41y).

Interventions: Not applicable.

Main Outcome Measures: Two experienced examiners completed 2 blinded goniometric STCA and 2 blinded visual STCA measurements on each subject's right and left ankles in random order.

Results: Quantitative visual and goniometric STCAs were similar (visual mean range, 5.61 degrees -6.50 degrees valgus vs goniometric mean range, 5.50 degrees -6.94 degrees valgus), and both measurements exhibited good to excellent intrarater reliabilities (intraclass correlation coefficient [ICC] range, .80-.94; 95% prediction limits, 1.51 degrees -2.06 degrees ). Interrater ICCs were only fair for both measurement methods (.50-.75; 95% prediction limits, 2.2 degrees -4.1 degrees ). In terms of relative reliability, the visual STCA and goniometric STCA exhibited good to excellent agreement (ICC range, .64-.95).

Conclusions: The STCA as described herein exhibited acceptable intrarater reliability for clinical use but may not be acceptably reliable between experienced examiners. The visual and goniometric STCA measurements were quantitatively similar and exhibited similar reliability. Using either method, changes of up to 2 degrees over time may be attributable to measurement error. Clinicians may consider using either STCA measurement in evaluating patients with lower-limb injuries or during screening of high-risk populations.