Chondrocalcinosis - Causes, Clinical Features, and Treatment

Introduction

People all over the world suffer from pain and inflammation in their joints due to a variety of reasons. This can cause severe discomfort and jeopardize the normal living of the affected individuals. One such common condition is chondrocalcinosis, which is a deposition disease.

What Is Chondrocalcinosis?

Chondrocalcinosis is a chronic medical or rheumatologic condition that is characterized by deposition of calcium pyrophosphate crystals. This crystal deposition process occurs mainly in the joint cartilage. Both hyaline and fibrocartilage are affected in this process. The joint cartilages mainly affected by this crystal deposition are knees, hips, and wrists. Since there is an accumulation of calcium pyrophosphate crystals, this disease is otherwise called calcium pyrophosphate deposition disease. A very sparse amount of hydroxyapatite, octacalcium phosphate, or dicalcium phosphate dihydrate is also deposited.

What Are the Causes of Chondrocalcinosis?

• As a part of aging, the deposition of calcium pyrophosphate crystals becomes very common. Thus, geriatric individuals are generally affected by chondrocalcinosis.

• Chondrocalcinosis frequently occurs due to an imbalance in the calcium metabolism in the body. When there is an excessive amount of calcium, there can be a predisposition to form calcium pyrophosphate crystals. Common disorders causing disturbances in calcium homeostasis are hyperparathyroidism and hypothyroidism.

• Along with calcium imbalance, the joint structures and chemistry also undergo a significant amount of change. In the synovial fluid surrounding joints, there is a balance and equilibrium of various minerals and substances. Changes in this composition, such as increased levels of inorganic pyrophosphate (a natural inhibitor of crystal formation) or alterations in pH levels, can promote the formation of calcium pyrophosphate crystals by the process of nucleation.

• Similarly, damaged joints (especially in conditions like osteoarthritis) can release substances that trigger the precipitation of calcium pyrophosphate crystals surrounding the joints. Damage to the joints can also be due to injury or microtrauma.

• Iron overload in the body (hemochromatosis) can also increase the incidence of calcium pyrophosphate crystal accumulation within the joint cartilages.

• Hypomagnesemia and kidney dysfunction can also cause impaired mechanisms and result in chondrocalcinosis.

• In some cases, genetic mutations involving the ANKH or COL2A1 gene are considered responsible for causing familial chondrocalcinosis.

What Are the Clinical Features of Chondrocalcinosis?

Local Features Seen in Chondrocalcinosis:

• Joint pain is the first feature noted in chondrocalcinosis. There is a dull, achy pain that occurs for a chronic period of time. Sometimes, there is an acute flareup of the inflammatory process. In such cases, the patients may complain of severe pain surrounding the joints.

• Edematous joints are also noted to be tender on palpation.

• Patients may complain of difficulty with movements, especially due to stiffness or restriction around the joints.

• The affected joints may appear red (erythematous). There is associated warmth around the area.

• Performing daily routine tasks becomes very difficult for such people due to the continued presence of inflammation and associated pain.

• In advanced cases of chondrocalcinosis, joint deformities may develop due to chronic inflammation surrounding affected cartilage, cartilage erosion, and joint damage. Bony overgrowth or malalignment of joints is noted.

Systemic Features Noted Are:

• Fever.

• Malaise.

• Fatigue.

• Weight loss.

• Involvement of multiple joints at the same time.

How to Diagnose Chondrocalcinosis?

• A physical examination after taking history is the first step to diagnose chondrocalcinosis. Physical examination of the affected joints can clearly elicit pain and swelling surrounding the region. Patients should also be asked for underlying comorbidities that affect calcium homeostasis and trigger the precipitation of calcium pyrophosphate crystals (like hyperparathyroidism, hyperthyroidism, or Wilson disease).

• Radiographic investigations are done following a physical examination. X-rays depict the calcium pyrophosphate crystal deposition as homogeneous linear or punctate radiopacities surrounding the joint. Joint degeneration and inflammation are also depicted through X-rays.

• In some patients, ultrasonographic imaging may be employed to look for calcium pyrophosphate crystal deposits within the joint. Along with the depiction of crystal deposition, ultrasonography also helps identify the presence of inflammation and soft tissue involvement surrounding the affected joint.

• The most reliable diagnostic method for chondrocalcinosis is the analysis of synovial fluid (arthrocentesis). Synovial fluid is aspirated for examination. The fluid appears cloudy or milky white in chondrocalcinosis. Microscopic examination of the synovial fluid reveals the characteristic presence of rhomboid or rod-shaped calcium pyrophosphate crystals. These crystals appear positively birefringent under polarized light microscopy. The calcium pyrophosphate crystals may be present in clusters or dispersed randomly within the synovial fluid.

• The synovial fluid also shows presence of white blood cells (due to inflammatory process). Also, the synovial fluid obtained during joint aspiration may appear turbid or slightly viscous.

• When the synovial fluid is stained with H&E (Hematoxylin and Eosin), blue coloured crystals are noticed.

Accessory Tests Done:

• Since imbalance in calcium metabolism is the key factor in the causation of chondrocalcinosis, laboratory tests are done to evaluate the underlying reason for disrupted metabolism.

• Parathormone levels, thyroxine levels, and levels of iron, copper, and calcium are evaluated through laboratory tests to identify the reason.

How to Treat Chondrocalcinosis?

• Pain caused due to chondrocalcinosis is treated with non-steroidal anti-inflammatory agents. Pain and inflammation due to acute flareup of the inflammatory response are managed by prescribing Colchicine.

• If arthritis causes calcium crystal precipitation, it is treated using disease-modifying antirheumatic drugs (DMARDs). This can suppress the inflammatory action surrounding the cartilage.

• To reduce the stress surrounding the affected joints, the patients are asked to manage their weight and reduce any kind of exertional activities.

• The diagnostic procedure arthrocentesis done will also act as a treatment modality as it removes excess synovial fluid that is causing inflammation in the region.

• In severe cases of chondrocalcinosis with significant joint damage or deformity, surgical interventions such as joint debridement or joint replacement surgery may be suggested to improve joint function.

• Apart from treating the chondrocalcinosis, the comorbidities associated with the incidence of this condition should be treated. For example, hypothyroidism is treated with Levothyroxine administration.

• Adjuvant drugs like Hydroxychloroquine and interleukin-1 receptor antagonists (Anakinra) are prescribed to reduce the process of inflammation.

• Inflamed synovium is also removed through radiosynovectomy.

Conclusion:

Chondrocalcinosis is a painful and potentially debilitating condition where there is precipitation and aggregation of calcium pyrophosphate dihydrate crystals within the joint cartilage. While there is no cure for chondrocalcinosis, there are several ways to manage the causative agents and symptoms. As a part of the research, new anti-crystal agents like Probenecid or Phosphocitrate are used to lower phosphate levels and inhibit the formation and accumulation of calcium pyrophosphate crystals.