Calcific shoulder tendonitis happens when a naturally occurring mineral present in the human body (hydroxyapatite) deposits within the tendons of the group of muscles around the shoulder (the rotator cuff). This condition is more frequent in women than men and is more common aged between 30 and 60 years. Often patients experience of long-lasting, slow-onset and/or intermittent shoulder pain caused by the inflammatory response of the body to resorption of the calcification. This happens as part of the natural cycle of the calcific deposit, which consists of three phases: formative, resting and resorptive, with the latter being the most painful. Sometimes a minor trauma or repetitive movement might irritate the tendon and the shoulder becomes very painful without any real resorption of calcific crystals.