Calcific tendonitis is a common condition that occurs when deposits of calcium accumulate within a tendon, most frequently affecting the rotator cuff in the shoulder. While many people may have these deposits without knowing it, a significant portion experience sudden and severe pain. This intense discomfort is the hallmark feature of the condition, often leading individuals to seek emergency medical attention due to the sudden onset and sharpness of the agony. Understanding why this mineral deposit causes such suffering requires a closer look at the physical composition of the calcium and the body’s attempt to resolve the issue.
Anatomy of Calcium Deposits
The deposits responsible for calcific tendonitis are composed of highly organized calcium hydroxyapatite crystals. This is the same mineral compound that gives bone its rigidity, but here it is lodged within the soft, flexible tissue of a tendon. While the condition can occur in various tendons throughout the body, the supraspinatus tendon of the rotator cuff is the most commonly affected site, accounting for a vast majority of cases.
The process begins with a formative phase, where the crystals are laid down in the tendon tissue, often without any associated pain. During this stage, the deposit is a dense, solid mass that may be visible on an X-ray as a uniform, well-defined spot. Scientific analysis reveals these deposits are made of rod-like nanocrystals aggregated into larger structures. This initial phase is essentially a silent physical change within the tendon structure.
The Mechanism of Extreme Pain
The debilitating pain begins when the body attempts to naturally clear the foreign material in what is known as the resorptive phase. The immune system initiates a biological response to break down and absorb the calcium, which is the direct cause of the intense, acute pain. During this transformation, the solid calcium deposit changes consistency, becoming a pressurized, liquid-like substance often described as having a “creamy” texture.
The most significant factor in the severity of the pain is the drastic increase in pressure within the confined space of the tendon. The liquefied calcium paste swells but has nowhere to escape, creating high internal tension that presses intensely on the surrounding pain receptors, or nociceptors, embedded in the tendon tissue. This localized internal pressure results in a deep, throbbing ache that often worsens at night.
A second potent factor is the chemical irritation caused by the released calcium material. As the aggregates of hydroxyapatite crystals fragment, they release needle-like nanocrystals that are highly inflammatory. These microscopic crystals trigger a strong inflammatory cascade, attracting immune cells and activating signaling pathways, which release powerful inflammatory mediators. This chemical environment sensitizes the nerve endings, making the area tender and painful to movement.
Furthermore, the body’s cleanup effort involves increased blood flow, or neovascularization, around the deposit. This influx of blood brings more inflammatory cells and also contributes to the swelling and pressure within the already compressed space. The combination of extreme pressure, aggressive chemical inflammation from the fragmented crystals, and heightened sensitivity creates the characteristic, excruciating pain of calcific tendonitis.
Strategies for Pain Relief
For individuals experiencing the acute, intense pain of the resorptive phase, initial treatment focuses on rapidly reducing the inflammation and pressure. Non-steroidal anti-inflammatory drugs (NSAIDs) are a first-line defense, working to mitigate the chemical irritation and reduce the overall inflammatory response. However, given the severity of the pain, these oral medications are often insufficient on their own.
A common and effective intervention is an ultrasound-guided corticosteroid injection. The corticosteroid is delivered directly into the subacromial bursa, the small fluid-filled sac near the tendon, to quickly calm the surrounding tissue and provide immediate relief from the inflammatory pain.
For a more direct attack on the physical deposit, a procedure known as barbotage, or percutaneous irrigation, may be performed. Barbotage involves using a fine needle, guided by ultrasound, to puncture the deposit and aspirate the pressurized, creamy calcium material, directly relieving the tension and removing the source of chemical irritation. Another non-surgical option is Extracorporeal Shockwave Therapy (ESWT), which uses high-energy sound waves directed at the deposit to mechanically fragment the calcium. The goal of both barbotage and shockwave therapy is to break up the mass, accelerating the body’s ability to resorb the fragments and quickly resolve the acute pain phase.