Crystalline Arthritis

Original Editor - Yasmin Maraya S Verzosa
Top Contributors - Yasmin Maraya S Verzosa and Kim Jackson

Overview

Crystalline Arthritis, collective term used for crystal depositions in the joints and often in soft tissues. In primary care, it is one of the most common musculoskeletal conditions. Arthritis, in different stages can be acute, chronic or asymptomatic; In Crystal Arthropathies, this type of arthritis is due to several types of crystals that accumulated in joints and other soft tissues.

The three main types of crystal arthritis:

• Gout - Monosodium urate (MSU)
• Calcium pyrophosphate (dihydrate) deposition disease (CPPD)
  • Pseudogout or Chondrocalcinosis
• Hydroxyapatite deposition disease (HADD)
  • Calcium hydroxyapatite (CHA)
  • Basic calcium phosphate crystal deposition disease

Clinically Relevant Anatomy

Joints
First Metatarsophalangeal Joint	The big toe is most commonly affected (gout or podagra).
Knees	Commonly affected in CPPD and also seen in gout.
Ankles	Frequently involved in gout attacks.
Shoulders	Seen in Milwaukee shoulder syndrome, a type of chronic destructive arthropathy, It usually affects older women that develops in the shoulders.
Wrists	Commonly affected in CPPD and sometimes in gout.
Elbows	Olecranon bursa can be involved in gout.
Digits	Particularly the small joints (interphalangeal joints) and wrist, often affected in CPPD and sometimes in gout.

Soft Tissues and Cartilages
Synovium	The joint lining is inflammed due to crystal deposition.
Tendons and Tendon Sheaths	Can be involved in chronic gout leading to tophi formation.
Bursae	The olecranon and prepatellar bursae can be involved, particularly in gout.

Specific Structures
Tophi	MSU deposits commonly found in chronic gout, usally in the ears, fingers, elbows, and Achilles tendon.
Chondrocalcinosis	Calcification seen in cartilages, indicative of CPPD, particularly in the knees and wrists.
Periarticular Tissues	Inflammation and pain can extend to the tissues surrounding the affected joints.

Aetiology

The aetiology of Crystalline Arthritis is usually multifactorial, this includes— genetic predisposition, medical comorbidities, and nutrition/dietary habits of a patient. In rare instances, a single genetic defect may be the cause of these type of conditions, often linked with other medical complications. Regardless of the underlying cause, the laboratory results indicate elevated serum uric acid, which can manifest as clinical gout in some individuals..

Pseudogout, characterized by calcium pyrophosphate (CPP) deposition disease, is thought to result from an imbalance between pyrophosphate production and pyrophosphatase levels in affected soft tissues like cartilages. When pyrophosphate accumulates in the synovium and surrounding tissues, it combines with calcium to form CPP crystals..

These ultramicroscopic crystals, which appear in snowball-like clumps, are found in various rheumatic conditions such as calcific tendinitis, calcific periarthritis, and some cases of progressive systemic sclerosis and dermatomyositis. Additionally, they are present in the synovium and cartilages of patients with advanced degenerative arthropathies that cause joint space narrowing visible on x-ray.

HADD encompasses a range of conditions, including calcific tendinitis, other periarticular hydroxyapatite deposits, and hydroxyapatite-induced arthritis. Other terns used for HADD are calcific tendinosis, peritendinitis calcarea, calcific peritendinitis and bursitis, and hydroxyapatite rheumatism. CHA is the most common type of calcium found in the human bone and is the most frequently encountered type of pathological calcification in the body..

Pathology

CPPD crystals seen under polarizing light microscopy. These crystals appear as weakly positive birefringent rhomboidal crystals.

Acute articular inflammation is the hallmark of crystal-induced arthritis, albeit joint damage or long-term impairment are uncommon outcomes. It was determined that crystals can induce arthritis when MSU crystals were found in patients with joint effusions of gouty arthritis. Additional crystals that have been linked to arthritis include CHA crystals (calcific periarthritis, acute arthritis), CPPD crystals (chondrocalcinosis, pseudo-gout), and deposition of corticosteroid crystals (which can occasionally cause arthritis when injected intra-articularly).

Crystal-induced arthritis can be diagnosed by either extracellular or seen as white blood cell-engulfed crystals. The risk of concurrent infections or other inflammatory forms of arthritis does not disappear in the presence of crystals. BCP crystals have the potential to severely inflame the periarticular space or joints..

Clinical Presentation

Gouty tophi on the elbow of a middle-aged male nurse.

The clinical manifestations of crystal arthritis types are frequently distinctive enough to set them apart from other inflammatory arthropathies and from one another. Nevertheless, diagnostic errors may occur, resulting in improper or delayed treatment. MSU crystal precipitation is the primary cause of gout which is the most prevalent crystal arthropathy. Inflammatory symptoms resulting from crystal deposition in and around joints are also linked to two other important forms of crystals, (1) basic calcium phosphate crystal (hydroxyapatite), also called HADD and (2) CPPD, which causes pseudogout.

Gout Intense pain on affected area Tenderness, even with a light touch Swelling Stiffness Discolouration or redness Warmth, giving a sensation as if the joint is “on fire”

CPPD Sudden, intense joint pain Skin discolouration or redness Swelling Stiffness A feeling of heat or warmth in or around a joint

HADD Acute onset of significant joint pain Swelling Tenderness Inflammation Decreased mobility in the affected joint

Diagnostic Procedures

Radiographic chondrocalcinosis. Dense deposits of CPPD are seen in this knee radiograph in the fibrocartilage of the meniscus.

Synovial Fluid Analysis

• For the diagnosis of gout, MSU crystal identification is still considered the gold standard. A gout flare-up is identified by the observation of MSU crystals in the synovium that have been damaged, utilizing compensated polarized light microscopy.

Laboratory Study

• The results often presents with WBC elevation, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) during acute gouty arthritis. These results are nonspecific and do not confirm nor differentiate the diagnosis of gout from septic arthritis.

Radiographic chondrocalcinosis. Dense deposits of CPPD are seen outlining the contours of the articular cartilage in this knee radiograph.

Imaging

• Plain radiographs and ultrasonography scans show if there are any crystals in the affected joints and soft tissues, as well as excess synovial fluid in the joint, or there is an existing joint damage already. Sometimes, advanced imaging such as computed tomography (CT) and magnetic resonance imaging (MRI) may also be used to detect the presence of crystal deposition.

Outcome Measures

• Arthritis Impact Measure
• Arthritis Hand Function Test (AHFT)
• Pain Catastrophizing Scale
• Chronic Pain Grade Scale
• Numeric Pain Rating Scale
• Visual Analogue Scale

Management / Interventions

CPPD Treatment

It is not possible to fully resolve or arrest the development of calcium pyrophosphate (CPP) dihydrate crystals. Nonetheless, treatment usually result in the resolution of joint discomfort and edema. The type of crystal deposition determines the appropriate intervention, which may include but are not limited to the following:

• Immobilisation: Patients experiencing a flare may be advised to avoid weight-bearing activities, such as walking or running if the lower extremities are involved. Excessive movement and strenuous activities should also be limited to minimize pain and swelling. In some cases, a temporary splint may be recommended to restrict joint movement.
• Aspiration and/or Injection: If one or two joints are affected during the acute phase, joint aspiration and/or injection would likely be the preferred treatment option. To further reduce pain and release pressure in the affected joint, fluid and crystals from the damaged joint are aspirated by a medical doctor. To lessen inflammation, the attending physician may use glucocorticoid (steroidal) injections.
• Pharmacologic treatment:
  • Oral anti-inflammatory medications is an option to prevent attacks of acute phase and manage chronic phase, physicians prescribe nonsteroidal anti-inflammatory drugs (NSAIDs), oral glucocorticoids, or colchicine may be preferred over joint injections. Usually, these medications are continued until the flare resolves.
  • Immunosuppressive drugs are also prescribed to further lessen inflammation by suppressing the immune system, patients with acute or chronic phases may occasionally need to take immunosuppressive medications. For example, patients experiencing significant flare-ups in acute phase may be administered with disease-modifying antirheumatic drugs (DMARDs) such as canakinumab (Ilaris) or anakinra (Kineret), particularly if they are not responding to other interventions or cannot tolerate other medications.

Icing on the ankle joint.

Patient education is essential in order to manage symptoms and avoid flare-ups. Patients should be made aware of the importance of maintaining enough hydration, as this can potentially lessen the frequency of flares by lowering the body's uric acid or calcium pyrophosphate. Furthermore, educating patients about lifestyle and dietary changes—such as cutting back on food high in purines if they have gout or keeping a balanced diet to control calcium levels—can make a big difference in the patient's overall wellbeing.

Heat and cold modalities such as hot compress and icing, may alleviate pain; Physical Therapy is also an intervention to aid in strengthening and increasing the flexibility in the muscles and soft tissues around the joints, which could also be beneficial for the patient.

According to PU Farin, et al, "Recalcitrant CHA deposits can be removed surgically or with image-guided aspiration."

Summary

• Crystalline arthritis is caused by the deposition of crystals in the joints.
• The two main types are gout (MSU crystals) and pseudogout (CPPD).
  • Another type is basic calcium phosphate crystal deposition disease (HADD).
• Symptoms of these type of arthritis include sudden, severe pain, swelling, and discolouration/redness in the affected joint.
  • One or more joints may be affected in an acute (flare-up) or chronic phase.
• Diagnosis is confirmed through synovial fluid analysis, imaging, and laboratory tests.
• Treatment typically involves pain relief, oral anti-inflammatory medications, aspiration/injection, and lifestyle changes.
• Preventive measures include patient education, dietary modifications, and adequate hydration.
• Crystalline arthritis can lead to joint damage if left untreated.
• Early detection and intervention is necessary for managing symptoms effectively.