The primary objective of this study is to compare OSTENIL® TENDON (2% hyaluronan) and Extracorporeal Shock Wave (ESWT) therapy in the treatment of painful Achilles tendinopathy.

Inclusion Criteria:

• Male and female patients between 18 and 75 years of age.
• Good general health condition.
• Signed written informed consent.
• Painful Achilles midportion tendinopathy since more or equal than 6 weeks.
• Pain according to VAS (Huskisson, 100 mm) more or equal than 40 mm.
• Ensured compliance of subjects over the whole study period.

Exclusion Criteria:

• Concomitant or previous participation in a clinical investigation within the last 3 months prior to study inclusion.
• Infection or relevant skin disease at study relevant site.
• Blood coagulation disorder or intake of blood thinner (e.g. Marcumar).
• Known hypersensitivity to hyaluronic acid (HA) preparations or to the constituents mannitol, sodium chloride, disodium phosphate and sodium dihydrogenphosphate.
• Contra-indications for ESWT application in study relevant area (e.g. recent surgery, malignant tumour, local osteomyelitis or open epiphysis).
• Severe intercurrent illness (e.g. uncontrolled diabetes mellitus, peripheral neuropathy), which in the opinion of the investigator, may put the patient at risk when participating in the study, or affect the patient's ability to take part in the study.
• Concomitant disease at study relevant site (e.g. insertion tendinopathy at Achilles tendon) influencing study evaluation.
• Diseases or characteristics judged by the investigator to be incompatible with the assessments and/or procedures for the study evaluation.
• Intake of concomitant medications not allowed which might interfere with the functional assessment of the study (e.g. immunosuppressive drugs within the last 3 months).
• Previous therapies (except non-steroidal anti-inflammatory drugs (NSAID)) at study relevant site within the last 4 weeks prior to study inclusion.
• Use of NSAIDs within the last week prior to study treatment.
• Recent history of drug and/or alcohol abuse (within the last 6 months).
• Pregnant or lactating females.
• Participants of childbearing age (pre-menopausal) who do not accept the use of methods of birth control with pearl index of at least 1 (i.e. oral contraceptives, vaginal ring, hormone-releasing Intrauterine Device (IUD), implants, depot syringes, hormone patch, double barrier method, tubal ligation, vasectomised partner,…) during the treatment period and the first 4 weeks of follow-up period.
• Subjects not capable of contracting and of understanding the nature, risks, significance and implications of the clinical investigation and unable to form a rational intention in the light of these facts.
• Subjects unable to understand informed consent or having a high probability of non compliance to the study procedures and / or non completion of the study according to investigator's judgement (e.g. illiteracy, insufficient knowledge of local language).