Development and reliability of the Achilles Tendon Length Measure and comparison with the Achilles Tendon Resting Angle on patients with an Achilles tendon rupture

Abstract

Background: There is a need for a valid, reliable, and easily applicable clinical measure of the length of the Achilles tendon (AT) after rupture. This study examines the reliability of a new ruler based measurement, the Achilles Tendon Length Measure (ATLM) in comparison with the goniometer-based Achilles Tendon Resting Angle (ATRA).

Methods: Measurements were performed by two independent physiotherapists eight weeks after AT rupture on 28 patients treated non-operatively.

Results: The mean (SD) injured ATLM was 56.5 (2.3)cm, ICC_2.1 0.91(CI [0.72-0.97]), SEM 0.7cm (SEM% 1.2), MDC 1.9cm (MDC% 3.4). Corresponding data for the injured ATRA was mean 64.4° (3.9°), ICC_2.1 0.84 (CI [0.68-0-92]), SEM 1.5° (SEM% 2.4), MDC 4.3° (MDC% 6.6).

Conclusion: Both ATLM and ATRA showed excellent inter-rater reliability with low measurement error. Both measurements seem easy to use in clinical practice and potentially providing an indirect measure of the length of the AT after rupture.

Keywords: Achilles Tendon Length Measure; Achilles Tendon Resting Angle; Achilles tendon rupture; Elongation; Reliability.