Lupus is a chronic autoimmune disease where the immune system mistakenly attacks healthy tissues and organs throughout the body, including the skin, kidneys, heart, lungs, and joints. This article explores how lupus impacts the skeletal system, detailing the mechanisms of damage, specific conditions, and management strategies.
How Lupus Targets Bones and Joints
The autoimmune nature of lupus drives inflammation and damage within the skeletal system. The immune system produces autoantibodies that target healthy joint and bone tissues, leading to pain, swelling, and stiffness. Chronic inflammation disrupts bone remodeling, causing increased bone breakdown and reduced formation, contributing to bone loss. Corticosteroids, a common lupus treatment, also affect bone-building and bone-breaking cells, reducing new bone production and increasing resorption. They also impair calcium absorption, essential for bone strength.
Specific Skeletal Conditions Caused by Lupus
Joint pain (arthralgia) and inflammation (arthritis) are frequent symptoms, affecting about 95% of lupus patients. Lupus arthritis often affects small joints of the hands, wrists, and feet symmetrically. While causing tenderness, swelling, and morning stiffness, it typically leads to less bone erosion and is less severe than rheumatoid arthritis. Joint symptoms can also be migratory, or in some cases, Jaccoud’s arthropathy can develop, causing manually correctable finger deformities.
Osteoporosis, characterized by reduced bone density and increased fracture risk, is common. Lupus’s chronic inflammation contributes to bone loss by disrupting the bone remodeling process. Corticosteroid medications, widely used to manage lupus, are a significant factor in the development of osteoporosis. These drugs can decrease calcium absorption and interfere with bone formation, increasing the risk of fractures, even at relatively low doses over extended periods. Other contributing factors include kidney disease, which can affect calcium and vitamin D levels, and reduced physical activity due to lupus symptoms like fatigue and pain.
Avascular necrosis (AVN), also known as osteonecrosis, is a serious condition where bone tissue dies due to an interruption in its blood supply. This can lead to tiny cracks in the bone and eventual bone collapse, particularly in weight-bearing joints. AVN commonly affects the hips, knees, and shoulders. The primary risk factor for AVN in lupus patients is the use of high-dose corticosteroids, especially over long durations. Symptoms often include pain in the affected joints, which may worsen with weight-bearing activities and can progress to pain even at rest. Early detection of AVN can be challenging, as initial symptoms may be subtle or absent.
Managing Skeletal Complications of Lupus
Managing the skeletal complications of lupus involves a comprehensive approach aimed at reducing pain, preserving joint function, and preventing further bone damage. Medications form a core part of this strategy. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen are often the first line of treatment for joint and muscle pain. Disease-modifying antirheumatic drugs (DMARDs), like hydroxychloroquine, methotrexate, or azathioprine, are frequently prescribed to address underlying inflammation and slow disease progression, which can help protect joints from damage. Corticosteroids may be used for short periods or in higher doses to manage severe inflammation, but their long-term use is minimized due to skeletal side effects.
Physical therapy plays a significant role in maintaining joint flexibility and strength, helping to manage pain and improve mobility. Therapists can provide guidance on exercises that are suitable for individuals with lupus, including weight-bearing activities that support bone health. Lifestyle adjustments also contribute to skeletal well-being. A diet rich in calcium and vitamin D is important for bone strength, with supplements often recommended to ensure adequate intake, especially for those on corticosteroids or avoiding sun exposure.
Regular, appropriate exercise, such as walking, dancing, or weight training, can help strengthen bones and muscles, even with lupus-related fatigue or pain. Avoiding smoking and limiting alcohol intake also supports overall bone health. For osteoporosis, bone mineral density screenings are recommended, particularly within six months of starting corticosteroid therapy, with follow-up screenings every one to two years. A multidisciplinary team, including rheumatologists, physical therapists, and dietitians, often collaborates to provide tailored care, addressing the diverse skeletal challenges faced by individuals with lupus.