Basal Joint Arthritis: Understanding Symptoms, Causes, Diagnosis, and Treatments

What is Basal Joint Arthritis?

Basal joint arthritis, also known as thumb CMC joint arthritis or first carpometacarpal joint arthritis, is a common degenerative condition affecting the joint at the base of the thumb, leading to pain, stiffness, and functional impairment, particularly with activities requiring pinch and grip.

Understanding the Basal Joint (CMC Joint)

The basal joint, or first carpometacarpal (CMC) joint, is a critical articulation located at the base of the thumb. It connects the trapezium bone of the wrist to the first metacarpal bone of the thumb. Structurally, it's classified as a saddle joint, which allows for a remarkable range of motion, enabling the thumb to move across the palm and articulate with the other fingers. This unique design is fundamental to the human hand's ability to perform complex tasks, including:

• Opposition: Touching the thumb to the tips of other fingers.
• Flexion and Extension: Moving the thumb forward and backward.
• Abduction and Adduction: Moving the thumb away from and towards the palm.
• Circumduction: A circular motion combining the above.

This extensive mobility, while highly functional, also contributes to the joint's susceptibility to wear and tear over time, making it a common site for osteoarthritis.

What is Arthritis? (A Brief Review)

Arthritis is a general term referring to inflammation of one or more joints. While there are over 100 different types of arthritis, basal joint arthritis primarily refers to osteoarthritis. Osteoarthritis, often called "wear-and-tear" arthritis, is a degenerative joint disease characterized by the breakdown of cartilage—the smooth, slippery tissue that covers the ends of bones in a joint. Cartilage allows bones to glide over each other with minimal friction. When it deteriorates, the bones begin to rub directly against each other, leading to pain, swelling, stiffness, and loss of motion. In the context of the basal joint, this progressive cartilage loss directly impairs the thumb's crucial functions.

Causes and Risk Factors

Basal joint arthritis develops gradually, and while the exact cause isn't always clear, several factors increase an individual's risk:

• Age: It is the most significant risk factor. The condition becomes more common with advancing age, typically affecting individuals over 40.
• Gender: Women are significantly more prone to developing basal joint arthritis than men, often beginning around menopause. Hormonal factors are thought to play a role.
• Genetics: A family history of basal joint arthritis suggests a genetic predisposition.
• Prior Injury: A history of trauma to the thumb joint, such as fractures, dislocations, or sprains, can accelerate cartilage degeneration.
• Repetitive Stress: Occupations or activities that involve repetitive, forceful pinching, gripping, or twisting motions of the thumb can contribute to the development or worsening of the condition. Examples include certain manual labor jobs, knitting, or even excessive smartphone use.
• Ligamentous Laxity: Some individuals have naturally looser ligaments around the basal joint, which can lead to increased joint mobility and instability, potentially contributing to premature wear of the cartilage.

Signs and Symptoms

The symptoms of basal joint arthritis typically develop gradually and worsen over time. They can significantly impact daily activities and quality of life:

• Pain at the Base of the Thumb: This is the most common symptom. It's often described as a deep, aching pain that is exacerbated by activities requiring pinch, grasp, or twisting movements (e.g., opening jars, turning keys, writing, buttoning clothes).
• Stiffness: The thumb joint may feel stiff, especially in the morning or after periods of inactivity.
• Swelling: Localized swelling, tenderness, and warmth around the base of the thumb are common.
• Grinding Sensation (Crepitus): A grinding, popping, or clicking sensation may be felt or heard when moving the thumb.
• Decreased Range of Motion: Difficulty performing the full range of thumb movements, particularly opposition and abduction.
• Weakness: Reduced pinch and grip strength, making it challenging to hold or manipulate objects.
• Deformity: In advanced stages, the base of the thumb may appear enlarged or "squared off," and the thumb may adopt a "zigzag" deformity as other joints compensate.

Diagnosis

Diagnosing basal joint arthritis typically involves a combination of a thorough medical history, physical examination, and imaging studies:

• Clinical Examination:
  • The healthcare provider will inquire about the onset, duration, and aggravating/alleviating factors of your symptoms.
  • A physical assessment will evaluate tenderness, swelling, range of motion, and strength of the thumb.
  • A key diagnostic test is the "grind test," where the physician gently presses and rotates the thumb metacarpal into the trapezium. Pain and crepitus during this maneuver are strong indicators of basal joint arthritis.
• Imaging Studies:
  • X-rays are the primary diagnostic tool. They can confirm the presence of arthritis, show the extent of cartilage loss (evidenced by narrowing of the joint space), bone spurs (osteophytes), and bone cysts. X-rays also help rule out other conditions that might cause similar symptoms.
  • MRI or CT scans are generally not necessary for diagnosis but may be used in complex cases or to evaluate other soft tissue structures if other conditions are suspected.

Treatment and Management

Treatment for basal joint arthritis aims to reduce pain, improve function, and slow the progression of the disease. It typically begins with conservative (non-surgical) approaches.

Conservative (Non-Surgical) Approaches

• Rest and Activity Modification: Identifying and avoiding activities that aggravate the joint is crucial. Modifying how tasks are performed can significantly reduce stress.
• Splinting/Bracing: Wearing a custom or over-the-counter thumb splint (often a spica splint) can support the joint, limit painful movements, and provide rest, especially during activities or at night.
• Medications:
  • Over-the-counter pain relievers: Acetaminophen (Tylenol) can help manage pain.
  • Nonsteroidal Anti-inflammatory Drugs (NSAIDs): Oral NSAIDs (e.g., ibuprofen, naproxen) or topical NSAID creams can reduce both pain and inflammation.
• Physical and Occupational Therapy: A hand therapist can provide invaluable guidance:
  • Joint protection strategies: Teaching techniques to perform daily tasks with less stress on the joint.
  • Ergonomic adjustments: Recommending modifications to tools, workspaces, and daily habits.
  • Strengthening exercises: Focusing on muscles that support the thumb and hand, improving overall stability without directly stressing the arthritic joint.
  • Range of motion exercises: Gentle exercises to maintain flexibility without causing pain.
  • Modalities: Applying ice or heat to manage pain and inflammation.
  • Assistive devices: Suggesting tools that make tasks easier (e.g., jar openers, large-grip utensils).
• Corticosteroid Injections: An injection of a corticosteroid medication directly into the joint can provide significant, though temporary, pain relief and reduce inflammation. These are typically used sparingly due to potential side effects.

Surgical Options

When conservative treatments fail to provide adequate relief, or if the arthritis significantly impairs daily function, surgical intervention may be considered. Several surgical procedures are available:

• Trapeziectomy: This is the most common surgical procedure. It involves removing the trapezium bone, which eliminates the bone-on-bone rubbing that causes pain.
• Ligament Reconstruction and Tendon Interposition (LRTI): Often performed in conjunction with a trapeziectomy, this procedure uses a portion of a nearby tendon (like the flexor carpi radialis) to create a new ligament and/or fill the space left by the removed trapezium, providing stability and cushioning.
• Fusion (Arthrodesis): Involves permanently fusing the first metacarpal to the trapezium bone. This eliminates pain by preventing movement but sacrifices the mobility of the joint, making it less common for the CMC joint.
• Arthroplasty (Joint Replacement): Involves replacing the damaged joint surfaces with an artificial implant (prosthesis). This is less common for the basal joint compared to other joints like the hip or knee but is an option in select cases.

Recovery after surgery typically involves a period of immobilization in a cast or splint, followed by extensive hand therapy to regain strength and range of motion.

Prevention and Self-Care

While basal joint arthritis cannot always be prevented, especially given genetic and age-related factors, certain strategies can help manage symptoms and potentially slow progression:

• Ergonomic Adjustments: Be mindful of how you use your hands and thumb. Use ergonomically designed tools, modify gripping techniques, and take frequent breaks during repetitive tasks.
• Regular Exercise: Maintain overall hand and forearm strength and flexibility. Consult with a hand therapist for appropriate exercises that support joint health without causing undue stress.
• Listen to Your Body: Avoid activities that consistently cause pain in the basal joint. Modify or delegate tasks if necessary.
• Maintain a Healthy Weight: While less directly impactful on hand joints than weight-bearing joints, overall health and reduced systemic inflammation can be beneficial.

Prognosis

The prognosis for basal joint arthritis is generally good. Many individuals find significant relief and improved function with conservative management, often for many years. When conservative treatments are no longer effective, surgical options have a high success rate in reducing pain and restoring function. Early diagnosis and intervention can help manage symptoms and potentially slow the progression of the disease, allowing individuals to maintain an active and functional lifestyle.