Assessment of elasticity by ARFI sonography of ruptured achilles tendons – long-term results

Purpose: Rupture of the Achilles tendon is a common injury. Only a few studies have investigated the biomechanical properties of injured tendons compared to healthy tendons in the long-term results. Our objective was to compare the elasticity of injured tendons vs. non-traumatized tendons by ultrasound elastography in the long-term outcome. Our secondary objective was to investigate differences of operatively vs. non-operatively treated tendons.

Methods: Acoustic-radiation-force-impulse-elastography (ARFI) was performed on Achilles tendons of patients who had ruptured their Achilles tendon and received operative (O) or non-operative (N) treatment. We included patients who were injured 2 – 10 two to ten years prior to the examination (exclusion criteria: bi-lateral injury in their history). Both Achilles tendons (injured and healthy) of each patient were scanned in the distal, middle and proximal portion using ARFI sonography (Siemens Acuson 2000, 6 – 9 MHz probe). Statistical analysis was performed by using one-way ANOVA with Bonferroni's post-hoc testing and subgroup analysis by using paired t-test. Furthermore, healthy tendons of the patients were compared to tendons of healthy individuals (n = 36) without any Achilles tendon rupture in their history (control).

Results: 56 patients were included in the study [23 (N), 33 (O)]. Mean follow-up-time after injury was 67 ± 26 months [Mean ± SD]. No statistical significant differences (p < 0.05) were found between non-operatively and operatively treated ruptures (Fig. 1). Compared to the control group all injured tendons had significantly lower elasticity in ARFI measurements. No significant differences were found between the healthy tendon of the patients and the control group.

Fig. 1: ARFI results of all subgroups (A) and pooled injured subgroups (B) compared using One-way ANOVA with Bonferroni's multiple comparison test (black). Subgroups separately compared using paired t-test (grey). P-values: *≤0.05; **≤0.005; ***≤0.0001

Conclusion: Evaluating our patients, we found that previously ruptured tendons still showed deficiencies in elasticity as evaluated by ARFI-sonography after a long period of healing. No significant differences were found between non-operatively and operatively treated tendons.

Further investigations need to be performed in order to correlate ultrasound findings with clinical scores, biomechanical, and histological parameters.