What is Calcific Tendonitis?
Shoulder calcific tendonitis (also spelled calcific tendinitis) is a condition characterized by the deposition of calcium phosphate crystals in the rotator cuff tendons, predominantly the supraspinatus tendon. This condition often occurs in individuals aged 30 to 50 and is twice as common in women as in men. The disease is most frequently seen in the right shoulder joint and can affect both shoulders in approximately 10% of patients. The causes of calcific tendonitis are not fully understood, but theories include degenerative changes due to aging and a reactive process involving cellular metaplasia and inflammation.
Calcific tendonitis progresses through three stages:
- Precalcific stage: This stage involves early changes within the tendon that set the stage for the calcium deposition. This stage is when metaplasia occurs, where tenocytes (tendon cells) transform into chondrocytes (cartilage cells). This transformation leads to the formation of fibrocartilaginous tissue within the tendon.
- Calcific stage: This stage is characterized by the actual deposition of calcium crystals within the tendon. It can be further divided into three phases:
- Formative phase: Calcium crystals start to form and gradually increase in size within the tendon.
- Resting phase: The calcium deposit growth halts, and the deposits remain stable within the tendon.
- Resorptive phase: The body begins to break down and absorb the calcium deposits. This process involves cell-mediated phagocytosis, where macrophages and giant cells engulf and digest the deposits. Acute pain is often present due to the inflammatory response triggered by the resorption process.
- Postcalcific stage: This final stage involves the healing and remodeling of the tendon following the resorption of calcium deposits. The spaces left by the absorbed calcium deposits are filled with granular tissue, which eventually remodels into normal tendon tissue. This stage typically results in the resolution of symptoms as the tendon heals.
Symptoms of calcific tendonitis can vary depending on the stage of the disease. During the formative and resting phases, patients may experience mild or no symptoms. In the resorptive phase, however, acute and severe sudden shoulder pain often occurs, especially at night. Other symptoms include restricted shoulder movement, localized tenderness, and sometimes visible swelling. If left untreated, calcific tendonitis can lead to a frozen shoulder, a rotator cuff tear, or other complications.










