Clinical benefits of early-stage autologous conditioned serum and injectable platelet-rich fibrin on healing superficial digital flexor tendonitis in donkeys

Abstract

Injectable platelet-rich fibrin (I-PRF) has been explored for its regenerative potential, but its application in tendon healing remains unstudied. Autologous conditioned serum (ACS), commonly used in joint therapies, inhibits interleukin 1-mediated inflammation, though its role in tendon healing is not well established. This study aimed to evaluate the clinical benefits of I-PRF alone and in combination with ACS in tendon healing. Twenty-three donkeys with forelimb superficial digital flexor (SDF) tendonitis were examined at admission (T0) and randomly assigned to PRF/ACS treated group (n = 10), PRF group (n = 7), or included as a control group (n = 6). Among clinical parameters, tendon shape and weight-bearing scores at T150 were significantly improved (P < 0.001) in the PRF/ACS group compared to the control group. Regardless of the tendon cross-sectional area (T-CSA), all other ultrasonographic parameters showed significant improvement in the PRF/ACS group compared to the control group. T-CSA increased throughout the study in PRF group but significantly decreased at T150 in control and PRF/ACS groups. The combination therapy had a significant improvement in fiber alignment score (FAS) and T-CSA compared to PRF group. Early lesion resolution in PRF/ACS at T90 and later in PRF at T150 suggests superior healing in PRF/ACS group. Persistent increase in T-CSA in the PRF group indicates ongoing healing, while its reduction in the PRF/ACS groups reflects more progressed healing stages and superior outcomes. Conversely, the presence of hyperechoic dots and misaligned tendon fibers in the control group suggests inferior healing outcomes. Intralesional I-PRF combined with ACS significantly enhanced clinical and ultrasonographic healing characteristics in donkeys with SDF tendonitis.