The clinical trial is a prospective, randomized, controlled, two-arm, single-blind study, involving 118 patients affected by symptomatic OA of the knee joint. Eligible subjects will be randomly allocated to one of the two treatment groups, with a 1:1 randomization ratio. Respectively, 59 patients treated with a single intra-articular injection of aMAT, and 59 patients treated with a single intra-articular injection of PRP.