Lateral epicondylosis, also called tennis elbow or lateral epicondylitis, is a prevalent, painful syndrome of the elbow. It is refractory to conservative treatment measures, including rest, excentric and concentric exercises in approximately 20% of patients after 6 months. Corticosteroid injections can provide relief in the short term. Mini-open surgery may be proposed when the conservative treatment fails and studies have shown an efficacy of 70%. Ultrasound-guided tendon fenestration is a minimally-invasive technique which stimulates the physiological healing mechanisms of the tendon and appears promising for the treatment of chronic tendinopathies. To our knowledge, no studies have compared the US-guided fenestration technique to mini-open surgery for the treatment of chronic lateral epicondylosis.