Background: Platelet-rich plasma (PRP) injections are used to treat (Achilles) tendinopathies. Platelet-rich plasma has been injected at different locations, but the feasibility of PRP injections and the distribution after injection have not been studied.
Purpose: To evaluate (1) the feasibility of ultrasound-guided PRP injections into the Achilles tendon (AT) and in the area between the paratenon and the AT and (2) the distribution of PRP after injection into the AT and in the area between the paratenon and AT.
Study design: Descriptive laboratory study.
Methods: Fifteen cadaveric lower limbs were injected under ultrasound guidance with Indian blue-dyed PRP. Five injections were placed into the AT at the midportion level; 5 injections were located anterior between the paratenon and AT and 5 posterior between the paratenon and AT. The limbs were anatomically dissected and evaluated for the presence and distribution of PRP.
Results: All injections into the AT showed PRP infiltration in the AT as well as in the area between the paratenon and AT (median craniocaudal spread, 100 mm; range, 75-110 mm); 1 of 5 limbs showed PRP leakage into the Kager fat pad after AT injection. Allanterior and posterior injections showed PRP infiltration in the area between the paratenon and AT (median, 100 mm; range, 75-150 mm). The AT was infiltrated with PRP after 3 of 10 paratenon injections.
Conclusion: The "AT" and "paratenon" injections under ultrasound guidance proved to be accurate. Injections into the AT showed distribution of PRP into the AT as well as in the area between the paratenon and AT. All injections between the paratenon and AT showed PRP distribution in that area, as well as in the Kager fat pad.
Clinical relevance: Different PRP injection techniques were evaluated. This aids in the optimization of PRP injections in the treatment of midportion Achilles tendinopathy.