Value of ultrasound and magnetic resonance imaging in the assessment of Achilles tendon healing following percutaneous repair with the Dresden instrument

Background: Percutaneous Achilles tendon (AT) repair with the Dresden instrument is a safe and effective treatment for AT rupture within 15 days after injury. Follow-up includes clinical examination and imaging to assess the healing process and detect possible complications. The findings of each control visit determine the progression of the rehabilitation of each patient. Methods: We assessed the postoperative findings of all patients who underwent AT with the Dresden technique from May 2022 to September 2023, during a follow-up period of 6 months. The study population included 40 male patients between 18 and 59 years of age. Ultrasound (US) and magnetic resonance imaging (MRI) were performed in all patients at day 15 postoperatively and then monthly for 6 months. Results: All patients completed 6 months follow-up and 2 (5%) presented with postoperative wound dehiscence. No sural nerve lesions, reruptures, reoperations or other complications were seen. Both imaging methods showed excellent correlation of findings at all time points. Both methods were effective to assess the hematoma and structural changes of the healing process during the first 3 months. The use of US with Doppler was a useful tool to evaluate blood flow to the tendon stumps. After 3 months no significant morphological changes were observed but the US enabled a dynamic functional assessment of the tendon. After 4 months tissues showed homogenization and decrease of volume without further major changes. Conclusion: Both US and MRI proved to be excellent methods to assess the healing process after percutaneous AT repair. The US performed by an experienced investigator showed advantages over MRI in evaluating the gap between the tendon stumps, the possibility of evaluating the vascularity with Doppler US and assessing the functionality of the healing tendon with dynamic examination, besides being a cheap and easily accessible imaging method.