**3.3 Blind injection technique**

The same physician who carried out US-guided injections provided the blind injections. The blind injection was performed in a similar technique to the method described previously [16]. The subjects were placed in the supine position, with the slightly flexed knee as like for the US-guided methods; palpated the point of maximal tenderness and marked it; prepped the skin using a usual product; inserted the 25-gauge 38-mm needle to the skin perpendicularly into the maximal tender point until touching the bone gently. After that, the needle of 2–3 mm is withdrawn to avoid injecting into the conjoined tendon directly; the materials are injected into the syringe, which should easily flow.
