 Methods and design Randomized double blind controlled trial, a total of 80 patients will be randomly allocated into one of two groups: PRP or control. Interventions: PRP group, ultrasound USguided needling associated to delivery of multiple PRP depots each alternate week for a total of two interventions. Control Group: US-guided needling with lidocaine each alternate week for a total of two interventions. Main outcome measure: Changes in pain and activity levels, as assessed by Disabilities of the Arm, Shoulder and Hand DASHoutcome measure score, before and six months after intervention.The primary end-point is 25 reduction in DASH. The investigators will compare the percentage of patients, in each group, that achieve a successful treatment defined as a reduction of at least 25 in the DASH score. 