The goal of this observational study is to compare the outcomes of two different surgical techniques (Endoscopic Flexor Hallucis Longus transfer - Group 1 vs Minimally Invasive primary repair - Group 2) for patients with acute Achilles tendon rupture. The main questions to be answered are:

1. Which group's patients are more satisfied?
2. Which group's patients appear to have a greater complication rate?
3. Which group's patients have greater calf and ankle circumference compared to the unaffected limb?
4. Which group's patients have greater passive and active range of ankle motion compared to the unaffected limb?
5. Are group 1 patients characterized by strength deficit in hallux flexion power?

Two separate foot and ankle surgeons in Northern Greece prefer to use a different surgical technique in their respective patients with Acute Achilles tendon rupture.

The first one (A.E.) prefers to perform only Endoscopic Flexor Hallucis Longus transfer, while the second one (P.S.) prefers to perform only Minimally invasive primary repair assisted by the Achillon device (Percutaneous Achilles Repair System - PARS). They both agreed to enroll their recently operated patients (last 5 years) in this retrospective study, which will be conducted by the researcher (M.K.). The patient's study may be retrospective, nevertheless, the patients were randomly chosen and enrolled by a prospectively designed study protocol. Each surgeon applied the respective surgical treatment modality regardless of each patient's characteristics, biometrics, or comorbidities. Inclusion and Elimination criteria will be applied. The patient's satisfaction will be evaluated with the Achilles Tendon Total Rupture Score (ATRS). Complications will be documented. Calf and ankle circumference will be measured and compared to the contralateral healthy limb. Ankle passive and active range of motion will be measured and compared to the contralateral healthy limb. Possible correlations will be investigated regarding patient age, BMI, history of smoking, level of activity, and comorbidities.

Inclusion Criteria:

• Signed Consent Form
• Age between 18-75 years
• Acute Achilles Tendon Rupture (<3 weeks)
• Surgical Management with Endoscopic Flexor Hallucis Longus transfer or Minimally Invasive primary tendon repair
• More than 12 months postoperative follow-up
• Patients operated after 2015

Exclusion Criteria:

• Inability or Unwillingness to cooperate
• Medically unfit for examination (e.g. due to terminal illness)
• Age less than 18 or more than 75 years
• Non-operative Management as definitive treatment
• Surgical Management other than the ones described in the inclusion criteria
• Neglected Achilles Tendon Rupture (>3 weeks)
• Bilateral Achilles Tendon Rupture
• Patients operated before 2015
• Comorbidities interfering with the secondary outcomes (e.g. Venous insufficiency resulting in lower limb excessive edema interferes with ankle and calf circumference, rheumatoid arthritis and/or previous foot and ankle surgery interferes with active and passive range of motion of the ankle, etc)

Patients with Achilles tendon rupture operated exclusively with these two surgical techniques, by these two particular surgeons (A.E. and P.S.) in their respective hospitals (General Hospital of Naoussa, St Luke's Hospital).

The records of each patient to be enrolled belong to the respective surgeon (A.E. and P.S.). Thus, the records of each patient will be entrusted to the main researcher (M.K.) with the obligation to maintain doctor-patient confidentiality. The final study results will not reveal any sensitive patient data (de-identification). Photos and videos of each patient's examination may be taken after ensuring their written and oral informed consent.