Osteoarthritis, often termed "Degenerative Joint Disease," stands as the most prevalent joint disorder. It stems from the degradation of cartilage at the bone ends within a joint. This deterioration leads to joint stiffness and pain.
Various factors like obesity, joint injuries, muscular weakness around the joint, neuropathic joint (sensory nerve damage), inflammation in adjacent tissues, and rare genetic factors contribute to this cartilage decay.
What Happens in Osteoarthritis?
Commonly, osteoarthritis affects multiple joints, especially those bearing weight or under heavy use. This includes knees, hips, spine (back and neck), finger joints, and big toes. Conversely, wrists, elbows, and ankles are less frequently impacted unless there's a history of trauma, infection, or overuse.
Demographics and Symptomatology
Predominantly seen in the older population, osteoarthritis manifests in both genders. However, it's more typical in men below 45 and in women post-50. Despite its widespread occurrence, only a minority exhibit symptoms.
The Pathophysiology of Osteoarthritis
In osteoarthritis, the cartilage, serving as a joint cushion, undergoes water content reduction, degeneration, and erosion. This results in joint pain and swelling. Cartilage erosion follows a pattern:
- Age-related structural changes reduce elasticity, impairing its role in reducing joint friction.
- Cartilage degeneration leads to inflammation in nearby tissues and further cartilage erosion.
- Additional cartilage erosion increases bone friction and weight-bearing stress, causing bone thickening and osteophyte formation.
- As the condition progresses, joint inflammation intensifies, possibly leading to cyst formation and the presence of loose cartilage or bone fragments.
Impact of Synovial Fluid
The synovial fluid, vital for smooth joint movement, gets affected. Changes in its key component, hyaluronan, disrupt its lubricating efficiency.
Symptoms of Osteoarthritis
Typical symptoms include joint stiffness and pain after prolonged use or inactivity. Affected joints may also exhibit muscle weakness and reduced weight-bearing capacity.
Osteoarthritis in Different Joints
- Hips: Groin, inner thigh, or buttock pain; possible knee pain and limping.
- Knees: Pain during movement, particularly when climbing stairs, accompanied by audible joint sounds.
- Fingers: Aches, swelling, and the formation of Heberden’s or Bouchard’s nodes, generally not affecting joint function.
- Toes: Pain, particularly in big toes; exacerbated by certain footwear.
- Spine: Neck and back stiffness and pain, potentially radiating to shoulders, arms, hips, and legs. Advanced stages can lead to nerve compression, causing numbness or weakness.
Differences Between Osteoarthritis and Rheumatoid Arthritis
Many patients often confuse osteoarthritis with rheumatoid arthritis. It is important to understand that these two diseases are distinct from each other, and the variations between them are highlighted in the table provided below. Additionally, it is possible for an individual to experience both diseases simultaneously.
Another condition that can cause confusion is osteoporosis, a condition characterized by weakened bones due to decreased bone mass. This can result in fragile bones that are prone to fractures. In particular, spinal fractures may lead to a hunched back or a decrease in height.
| Osteoarthritis | Rheumatoid Arthritis |
|---|---|
| Typically begins around the age of 40. | Generally starts between the ages of 20 and 50. |
| Occurs in about two-thirds of individuals over the age of 65 and 10% of those with advanced symptoms. | Affects approximately 1% of the population in the United States. |
| Usually develops gradually over the years. | Can have an acute onset and progress rapidly over weeks or months. |
| Primarily affects a few joints, particularly weight-bearing joints or those subjected to strenuous use, and may occur on both sides of the body. | Typically affects the small joints of the fingers (excluding the joints closest to the fingertips) or toes, and must occur on both sides of the body. |
| Often characterized by minimal pain, swelling, redness, and warmth in the joints, with possible morning stiffness lasting less than 20 minutes. | Frequently accompanied by significant pain, swelling, redness, and warmth in the joints, with morning stiffness that usually lasts longer than 20 minutes, possibly for hours. |
| Affects weight-bearing joints or joints subjected to strenuous use, such as knees, hips, spine, and fingers, with wrists, ankles, and elbows being less commonly affected. | Primarily affects the small joints of the fingers and toes on both sides of the body, and can also involve the wrists, ankles, and elbows. |
| Usually not associated with fatigue or weight loss. | Can cause fatigue and weight loss. |
Causes of Osteoarthritis
Heredity
Certain patients and families develop osteoarthritis due to the genetic defect of collagen protein which is a component of cartilage. These families will have osteoarthritis at an early age but can also have it when getting older. These patients, particularly women, usually develop Heberden’s nodes and Bouchard’s nodes on the fingers. Some patients with genetic defect that causes abnormal shape of the joint such as abnormal bending of hip joints or knee joints, or with excess joint movement, may have a greater chance of developing osteoarthritis than normal people.
Obesity
Studies show that obesity is a risk factor for Osteoarthritis of the knees and also a factor that causes Osteoarthritis to get worse. Therefore, weight-gain prevention and weight reduction will help prevent the development of Osteoarthritis and improve disease condition.
Muscle weakness
Studies have shown that people with weak quadriceps muscles at the thighs may have a greater chance of developing osteoarthritis of the knees than normal people. In addition, the weak quadriceps muscles may also cause faster degeneration of the osteoarthritis-affected knees.
Trauma or overuse
Joint trauma increases the chance of osteoarthritis development. For example, football players with knee trauma will be at increased risk for osteoarthritis of the knees. Excess use of joints, such as frequent knee bending or frequent squats, will increase the risk of osteoarthritis of the knees more than in normal people. Therefore decrease of trauma or frequent knee bending will help reduce the chance for the development of osteoarthritis of the knees.
Osteoarthritis Prevention
As mentioned above, weight control and joint trauma prevention will help prevent the development of osteoarthritis.
Diagnosis of Osteoarthritis
To diagnose osteoarthritis, the physician will inquire about the patient's medical history and conduct a physical examination. X-ray or magnetic resonance imaging (MRI) of the joint may be necessary to determine the stage of the disease and rule out other causes. Joint fluid aspiration may be performed to diagnose other conditions or exclude causes such as gout, pseudogout, or joint infection.
Treatment of Osteoarthritis
Effective treatment of osteoarthritis aims to alleviate pain, improve mobility, and enhance daily activities. The treatment plan may include medication, weight control, physical therapy, and patient education about the disease. If conservative measures fail, joint replacement surgery can provide symptom relief and improve movement. The choice of treatment depends on the affected joint(s), disease severity, and the presence of other chronic conditions. Consideration is also given to the patient's occupation and its impact on daily activities.
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