Feasibility and Efficacy of Bone Marrow PRP Injection in Refractory Fissure Tendinopathies of the Lateral Epicondylar Tendons

Lateral epicondylitis with tendon tear resistant to conservative treatment remains a common clinical condition with limited therapeutic options before surgery is considered. Platelet-rich plasma (PRP) injections are used in tendinopathies because of their potential regenerative properties. More recently, platelet-rich plasma derived from bone marrow aspirate (bone marrow-derived PRP) has emerged as an alternative source of platelets and bioactive factors. However, the clinical implications of its different biological composition compared with peripheral blood-derived PRP remain poorly understood. This monocentric randomized pilot trial aims to assess the feasibility of the intervention and to estimate the effect of bone marrow-derived PRP compared with peripheral blood-derived PRP in patients with resistant partial-thickness lateral epicondylar tendinopathy. Participants will be randomly assigned in a 1:1 ratio to receive either bone marrow-derived PRP or peripheral blood-derived PRP injection. Clinical outcomes, pain, functional scores, imaging findings, safety, and feasibility parameters will be assessed over a 12-month follow-up period. The study is not powered to demonstrate superiority between treatments but is intended to generate preliminary effect estimates and feasibility data for the design of a future confirmatory trial.

Inclusion Criteria: * Diagnosis of chronic lateral epicondylitis with partial-thickness tendon tear of the common extensor tendon confirmed by ultrasound. * Symptoms persisting despite appropriate conservative treatment for at least 3 months. * Indication for platelet-rich plasma (PRP) injection established by the treating physician. * Ability to understand the study procedures and comply with follow-up requirements. * Written informed consent obtained prior to participation. * Affiliation to a health insurance system (as required by French regulations). Exclusion Criteria: * Full-thickness tear of the common extensor tendon. * Previous surgery of the affected elbow. * PRP injection in the affected elbow within the previous 6 months. * Corticosteroid injection in the affected elbow within the previous 3 months. * Current treatment with medications incompatible with PRP preparation according to study procedures. * Active infection at the injection site or systemic infection. * Known hematologic disorder affecting platelet function or coagulation. * Current anticoagulant therapy that cannot be interrupted according to study requirements. * Pregnancy or breastfeeding. * Participation in another interventional clinical trial that could interfere with study outcomes. * Any medical, psychiatric, or social condition that, in the investigator's opinion, could compromise participant safety or compliance with study procedures.