Summary Flexor Pronator Strains are acute or chronic muscle strains of the flexor pronator mass, distal to its origin on the medial epicondyle. Diagnosis is made clinically with medial elbow swelling and ecchymosis in acute strains withtenderness distal to the medial epicondyle. MRI studies can be used to help identify complete tears or UCL injuries. Treatment is generally nonoperative with rest, activity modifications and physical therapy. Epidemiology Demographics golfers cricket players throwing athletes Etiology Pathophysiology acute muscle tear single event of a large, eccentric force during resisted wrist flexion, forearm pronation, and valgus at the elbow chronic overuse can lead to acute flexor pronator rupture sudden onset of pain and flexor weakness chronic tendonitis repetitive elbow valgus, wrist flexion, and forearm pronation Associated conditions ulnar collateral ligament insufficiency should be ruled out in throwing athletes Anatomy Flexor pronator mass provides dynamic support to the medial elbow against valgus stress Flexor pronator mass includes (proximal to distal) Pronator Teres (median n.) Flexor Carpi Radialis (median n.) Palmaris Longus (median n.) FDS (median n.) Flexor Carpi Ulnaris (ulnar n.) Presentation History acute event of hitting the ground during golf, bat, or racquet swing history of throwing or racquet sports repetitive gripping and/or elbow valgus stress activities Symptoms pain medial elbow pain distal to the medial epicondyle chronic pain during late cocking/early acceleration Physical exam medial elbow swelling and ecchymosis in acute strain tenderness distal to medial epicondyle provocative tests pain with elbow extension and resisted wrist flexion or pronation examine for associated conditions negative moving valgus stress test normal neurovascular exam Imaging Radiographs usually normal MRI indications unclear source of medial elbow pain grade severity of muscle strain rule out other causes of medial elbow pain such as UCL rupture findings edema in flexor pronator mass partial tearing or complete rupture of flexor pronator mass Differential Medial epicondylitis UCL injury Valgus extension overload with posteromedial olecranon impingement Treatment Nonoperative NSAIDS, rest, physical therapy, steroid injections indications first line of treatment technique ROM and flexor pronator strengthening x 4-6 weeks corticosteroid injection for chronic flexor pronator tendonitis rarely needed avoid UCL due to risk of rupture outcomes typical resolution and return to sport in 4-6 weeks Operative primary surgical repair indications significant (>2.5 cm) retraction Complications Continued medial elbow pain and valgus instability unrecognized UCL insufficiency Prognosis Typically resolves with 4-6 weeks of activity restriction