Haglund's deformity, also known as "pump bump", is characterized by a triad of retrocalcaneal bursitis, tendoachilles bursitis, and a partial tear of the Achilles tendon. MRI is useful for evaluating the condition and can demonstrate fluid and inflammation in the retrocalcaneal and tendoachilles bursae as well as thickening and tearing of the Achilles tendon. The deformity is caused by a bony prominence on the back of the heel bone that irritates the Achilles tendon and associated bursae, commonly from overuse, ill-fitting shoes, or inflammatory conditions.