Summary

The study examined 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). Both ATLM and ATRA showed excellent inter-rater reliability with low measurement error.

Abstract

Background

A prolonged Achilles Tendon (AT) following AT rupture is associated with strength deficits and reduced function. The first three months after injury have been identified as the time when the main changes of the AT length occur. Therefore a valid, reliable, and easily applicable clinical measure of the length of the AT that can be used during this time period after rupture is needed.

Purpose/aim of study
To examine 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).

Materials And Methods

The development of ATLM originates from the well-known Matles test. The ATLM use identical positioning of the patient and feet, but aim to provide an objective assessment by measuring the exact distance between the feet and the examination couch with a ruler. As well as ATRA, the resting position of the feet is measured during ATLM as an indirect measure of the length of the AT. ATLM and ATRA measurements were performed by two independent physiotherapists eight weeks after AT rupture on 28 patients treated non-operatively. The data assessors were inter- and intra-rater blinded to outcome data.

Findings/results
The mean (SD) injured ATLM was 56.5 (2.3) cm, ICC2.1 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°), ICC2.1 0.84 (CI [0.68-0-92]), SEM 1.5° (SEM% 2.4), MDC 4.3° (MDC% 6.6).

Conclusions

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.