• Traumatology
• Foot Ankle Surgery

Background: Approximately five persons get injured with an Achilles tendon rupture every day in Denmark, and many of the patients have persisting functional deficits. A common problem after injury is elongation of the healed tendon, which is correlated with decreased muscle strength and function. Though, how to best measure tendon elongation is unclear. Furthermore, the clinical criteria for recommending operative treatment differ and are not evidence based why an individualized treatment selection protocol has been requested.

Purpose: The overall aims of this PhD was to evaluate the reliability and validity of outcome measures used to evaluate tendon elongation and to investigate the effect of an individualized treatment algorithm on the patients’ gait dynamics and tendon elongation within the first year after an Achilles tendon rupture.

Methods: In Study 1, the reliability of Copenhagen Achilles Length Measure (CALM), an ultrasound examination of tendon elongation, was investigated. In Study 2, the construct validity of two indirect measures for tendon elongation (Achilles Tendon Resting Angle, ATRA, and Achilles Tendon Length Measure, ATLM) was investigated using CALM as the gold standard. In Study 3, the effect of an individualized treatment algorithm (Copenhagen Achilles Rupture Treatment Algorithm, CARTA) on gait dynamics and tendon elongation was investigated in a three-armed randomized controlled trial.

Results: Study 1 found excellent inter-rater relative reliability of CALM (ICC ≥ 0.75). Measurement error on a group level ranged between 0.3-0.6 cm (18-29 SEM%) and on an individual level between 0.8-1.7 cm (47-81 MDC%). Study 2 found a linear relationship between ATRA, ATLM and CALM, which were statistically significant in all models (p<0.01). Study 3 found no statistically significant differences between the intervention group in comparison with the control groups. Among the intervention group, compared with the un-injured leg, the injured leg had decreased peak ankle plantarflexor moment (6%, p=0.039) and peak ankle plantarflexor power during pushoff (14%, p=<0.001) at 6 months. The moment was restored at 12 months, but the power was still reduced (with 7%, p=<0.027). Tendon elongation was also significant at 6 (17.7 mm, p=<0.001) and 12 months (19.4 mm, p=<0.001).

Conclusion: CALM had excellent reliability, but a quite large measurement error. Both ATRA and ATLM showed acceptable construct validity for assessing tendon elongation after rupture. Patients given individualized treatment using CARTA did not have better gait dynamics or less tendon elongation than patients treated as usual.

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Paper 1
Paper 2