gms | German Medical Science

Objectives: The rupture of the Achilles tendon (AT) is a common injury and the healing of tendon tissue results in scar tissue formation. Only a few studies have investigated the biomechanical properties of healed, formerly ruptured AT. The purpose of this study was to investigate the elastic properties of healed AT ruptures in the long-term. Secondary objectives were finding differences in various areas of the tendons, differences of operatively vs. non-operatively treated tendons and the correlation of elastic properties with the clinical outcomes.

Methods: Patients that suffered from AT rupture more than 2 years prior to the study were recruited for an elastographic examination. Exclusion criteria were bi-lateral injury in their history, arthrodesis of one of the upper ankle joints, neuropathic or malignant diseases, age < 18 years. Acoustic-radiation-force-impulse- elastography (ARFI) was performed in the mid-part and distally on the calcaneal insertion. Results were compared to patients' contralateral non-injured AT and an additional healthy population. For statistical evaluation, corresponding t-tests, reliability analysis, and correlation analysis with clinical scores were performed.

Results and Conclusion: 49 patients were included with a mean follow-up-time of 76±32 months after rupture. Highly significant differences were identified in the mid-part of the tendon with a mean shear wave velocity of 1.8±3.5 m/s of the formerly ruptured tendons and 2.7±1.6 and 2.8±1.6 m/s of the contralateral tendon and the healthy population, respectively (see figure). Operatively and non-operatively treated groups showed no differences. There was no correlation of the elastographic measurements and the clinical outcome (Kendall's s t-b 0.190/-0.160 for VISA-A score and -0.129/-0.079 for FAOS score (dist/mid, respectively) (Figure 1 [Fig. 1]).

Evaluating our patients, we found that previously ruptured AT show significant deficiencies in elastic properties as evaluated by ARFI-sonography even after a long period of tendon healing. This aspect resembles the characteristics of scar tissue formation during tendon healing. Differences mainly originate from the mid-portion of the AT, in which most of the AT ruptures occur. Choice of treatment has no impact on the elastographic outcome. Elastographic results do not necessary correspond with the subjective appearance. More prospective studies are needed in order to evaluate the clinical value of shear wave elastography for monitoring purposes.