MP Arthritis: Understanding Causes, Symptoms, Diagnosis, and Treatment

What is MP Arthritis?

MP arthritis, or metacarpophalangeal joint arthritis, refers to inflammation and degeneration of the joints connecting the hand bones (metacarpals) to the finger bones (phalanges), most commonly affecting the knuckles at the base of the fingers.

Understanding the Metacarpophalangeal (MP) Joint

The metacarpophalangeal (MP) joints are the main knuckles of the hand, where the long bones of the palm (metacarpals) meet the first bones of the fingers (proximal phalanges). These joints are crucial for the intricate movements of the hand, allowing for flexion (bending), extension (straightening), abduction (spreading), and adduction (bringing fingers together). They are synovial joints, meaning they are enclosed by a joint capsule containing synovial fluid, which lubricates the joint and nourishes the cartilage. Articular cartilage covers the ends of the bones, providing a smooth, low-friction surface for movement and absorbing shock.

What is MP Arthritis?

MP arthritis is a condition characterized by the inflammation, pain, stiffness, and progressive degeneration of the metacarpophalangeal joints. This degeneration typically involves the breakdown of the articular cartilage, leading to bone-on-bone friction, formation of bone spurs (osteophytes), and subsequent inflammation of the joint lining (synovium). While any MP joint can be affected, the thumb MP joint and the MP joints of the index and middle fingers are frequently involved due to the stresses placed upon them during daily activities.

Types and Causes of MP Arthritis

MP arthritis is not a single condition but rather a general term encompassing various forms of arthritis that can affect these specific joints. The underlying cause often dictates the specific type of arthritis present:

• Osteoarthritis (OA): This is the most common form of arthritis, often referred to as "wear-and-tear" arthritis. It occurs when the protective cartilage on the ends of your bones wears down over time. In MP joints, OA can be a result of chronic mechanical stress, repetitive movements, or previous joint injury.
• Rheumatoid Arthritis (RA): An autoimmune disease where the body's immune system mistakenly attacks its own tissues, primarily the synovium (the lining of the joints). RA often affects the small joints of the hands and feet symmetrically, making the MP joints a common target. It leads to chronic inflammation, pain, swelling, and can cause significant joint deformity and loss of function.
• Psoriatic Arthritis (PsA): A form of arthritis that affects some people who have psoriasis, a skin condition characterized by red patches of skin topped with silvery scales. PsA can affect peripheral joints, including the MP joints, and may cause symptoms similar to RA.
• Gout and Pseudogout: These are forms of inflammatory arthritis caused by the accumulation of crystals in the joints. Gout results from uric acid crystals, while pseudogout involves calcium pyrophosphate crystals. While more common in the big toe, these conditions can affect any joint, including the MP joints, causing sudden, severe pain, swelling, and redness.
• Post-Traumatic Arthritis: This type of arthritis develops after an injury to the joint, such as a fracture, dislocation, or severe sprain. The injury can damage the articular cartilage or alter the joint mechanics, leading to premature wear and tear and the development of arthritis years later.

Common Signs and Symptoms

The symptoms of MP arthritis can vary in severity and may progress over time. Common indicators include:

• Pain: Often described as a deep ache, which worsens with movement, gripping, or pinching activities. It may be more pronounced after periods of rest or in the morning.
• Stiffness: Especially noticeable in the morning or after periods of inactivity. This stiffness can make it difficult to fully bend or straighten the fingers.
• Swelling: The affected MP joint may appear visibly swollen due to inflammation and fluid accumulation.
• Tenderness: The joint may be painful to the touch.
• Reduced Range of Motion: As the cartilage wears down and inflammation persists, the ability to move the finger at the MP joint may become limited.
• Grinding or Clicking Sensations (Crepitus): May be felt or heard during joint movement as rough surfaces rub against each other.
• Deformity: In advanced stages, particularly with inflammatory types like RA, the joint may become misshapen or deviate, affecting hand function.
• Warmth: The affected joint may feel warm to the touch due to inflammation.

Diagnosis of MP Arthritis

Diagnosing MP arthritis typically involves a comprehensive approach:

• Medical History and Physical Examination: Your healthcare provider will inquire about your symptoms, medical history, and perform a thorough physical examination of your hand, assessing joint swelling, tenderness, range of motion, and stability.
• Imaging Studies:
  • X-rays: Can reveal joint space narrowing, bone spurs (osteophytes), subchondral sclerosis (increased bone density beneath the cartilage), and erosions (bone damage) which are characteristic of different types of arthritis.
  • MRI (Magnetic Resonance Imaging): Provides detailed images of soft tissues, including cartilage, ligaments, and tendons, and can detect early inflammatory changes not visible on X-rays.
  • Ultrasound: Can visualize inflammation of the joint lining (synovitis), fluid accumulation, and early erosions.
• Blood Tests: May be ordered to rule out or confirm systemic inflammatory conditions like rheumatoid arthritis (e.g., rheumatoid factor, anti-CCP antibodies, ESR, CRP) or to check for elevated uric acid levels in suspected gout.
• Joint Fluid Analysis (Arthrocentesis): In some cases, fluid may be drawn from the joint and analyzed for crystals (gout, pseudogout) or signs of infection.

Management and Treatment Strategies

Treatment for MP arthritis aims to reduce pain, improve function, and slow disease progression. The approach depends on the type and severity of arthritis:

Conservative Approaches:

• Rest and Activity Modification: Avoiding activities that exacerbate pain and modifying daily tasks to reduce stress on the affected joint.
• Splinting/Bracing: Custom or off-the-shelf splints can provide support, reduce pain, and improve alignment, especially during activities or at night.
• Medications:
  • Over-the-Counter Pain Relievers: NSAIDs (nonsteroidal anti-inflammatory drugs) like ibuprofen or naproxroxen can help reduce pain and inflammation.
  • Prescription Medications: Stronger NSAIDs, disease-modifying antirheumatic drugs (DMARDs), biologics, or corticosteroids may be prescribed for inflammatory types of arthritis.
• Physical Therapy (PT) / Occupational Therapy (OT): A crucial component of treatment. Therapists can:
  • Teach joint protection techniques to minimize stress during daily activities.
  • Guide through therapeutic exercises to maintain or improve range of motion, flexibility, and strength of surrounding muscles.
  • Apply modalities like heat, cold, or ultrasound to reduce pain and inflammation.
  • Recommend assistive devices or adaptive equipment.
• Injections:
  • Corticosteroid Injections: Can provide temporary relief from pain and inflammation by injecting a powerful anti-inflammatory medication directly into the joint.
  • Hyaluronic Acid Injections: (Less common for MP joints but used in larger joints) can supplement the natural lubricating fluid.

Surgical Interventions:

Surgery is considered when conservative treatments fail to provide adequate relief or when joint damage significantly impairs function.

• Synovectomy: Removal of the inflamed joint lining (synovium), often performed in early rheumatoid arthritis to reduce pain and prevent further joint damage.
• Arthroplasty (Joint Replacement): For severe cases, particularly in the thumb MP joint or when multiple finger MP joints are involved, the damaged joint surfaces can be removed and replaced with an artificial implant (e.g., silicone elastomer implant).
• Arthrodesis (Joint Fusion): Involves fusing the bones of the joint together to create a solid, immobile joint. This eliminates pain but sacrifices motion. It is typically reserved for joints that are severely damaged and when stability and pain relief are prioritized over mobility.

Role of Exercise and Movement

For individuals with MP arthritis, appropriate exercise is vital for maintaining joint health and function.

• Gentle Range of Motion (ROM) Exercises: Regular, gentle movements help preserve joint flexibility and prevent stiffness. These can include carefully bending and straightening the fingers, and spreading them apart.
• Strengthening Exercises: Focus on strengthening the muscles that support the hand and wrist. Isometric exercises (contracting muscles without moving the joint) can be beneficial when joints are inflamed. Grip strengthening exercises (e.g., squeezing a soft ball) should be performed cautiously and only if pain-free.
• Low-Impact Activities: Engage in activities that do not put excessive stress on the MP joints.
• Consult a Professional: Always consult with a physical or occupational therapist. They can design a personalized exercise program that is safe and effective, considering your specific type and stage of arthritis, and teach you proper joint protection techniques.

Living with MP Arthritis: Practical Tips

Managing MP arthritis involves integrating various strategies into daily life:

• Joint Protection Techniques: Learn to use larger, stronger joints for tasks whenever possible. Avoid prolonged gripping, twisting, or pinching. Use both hands for heavy items.
• Pacing Activities: Break down tasks into smaller segments, taking frequent rests to avoid overstressing the joints.
• Assistive Devices: Utilize tools that reduce strain, such as jar openers, ergonomic utensils, large-grip pens, or button hooks.
• Heat and Cold Therapy: Apply heat (e.g., warm compresses, paraffin wax baths) to ease stiffness and pain, and cold packs to reduce swelling and acute inflammation.
• Healthy Lifestyle: Maintain a healthy weight to reduce overall stress on joints. A balanced diet rich in anti-inflammatory foods (e.g., omega-3 fatty acids, fruits, vegetables) may also be beneficial.

When to Seek Medical Attention

It's important to consult a healthcare professional if you experience persistent pain, swelling, or stiffness in your MP joints, especially if these symptoms interfere with your daily activities. Early diagnosis and intervention can significantly impact the long-term prognosis, helping to manage symptoms, prevent further joint damage, and preserve hand function. If you notice any sudden increase in pain, redness, warmth, or signs of infection, seek immediate medical attention.