Arthritis is one of the most common causes of chronic knee pain, stiffness, and reduced mobility. It can affect people of all ages, though it is most prevalent as we get older or after injuries that damage the knee joint. Two primary types of arthritis impact the knee: Osteoarthritis and Rheumatoid Arthritis. While both lead to similar symptoms, their underlying causes and progression are quite different.

Osteoarthritis of the Knee

Osteoarthritis, often called “wear-and-tear” arthritis, occurs when the cartilage that cushions the ends of the bones within the knee joint gradually breaks down. This cartilage acts as a smooth, protective layer, allowing the bones to glide easily during movement. When it begins to wear away, bones start to rub against one another, causing pain, swelling, stiffness, and sometimes a grinding or popping sensation.

Over time, osteoarthritis can lead to bone spurs, loss of joint space, and reduced range of motion. It usually develops slowly, but the symptoms can progress to the point where simple activities such as walking, climbing stairs, or standing for long periods become difficult.

Rheumatoid Arthritis of the Knee

Rheumatoid arthritis is an autoimmune disease that causes the immune system to mistakenly attack the lining of the joints, known as the synovium. This results in inflammation that can thicken the joint lining, damage cartilage, and erode the underlying bone. Unlike osteoarthritis, which usually affects one joint more than the other, rheumatoid arthritis tends to affect both knees and other joints throughout the body.

People with rheumatoid arthritis often experience stiffness in the morning that lasts longer than in osteoarthritis, along with joint swelling, warmth, and tenderness. Because it is a systemic condition, rheumatoid arthritis can also cause fatigue, low-grade fever, and other whole-body symptoms.

How Arthritis Affects the Knee

Regardless of type, knee arthritis can cause pain, stiffness, weakness, and instability. As the cartilage wears away or inflammation persists, movement becomes more restricted, and the surrounding muscles may weaken. Over time, everyday actions like walking, bending, or squatting may trigger pain or swelling.

Many patients describe their pain as aching or grinding deep within the joint, and it may worsen after activity or prolonged rest. In severe cases, deformity can occur as the joint loses its natural alignment.

Treatment Options for Knee Arthritis

Treatment for knee arthritis typically begins with conservative, non-surgical approaches designed to reduce pain, maintain mobility, and slow disease progression.

Conservative (Non-Surgical) Treatments

  • Physical therapy and exercise: Strengthening the muscles that support the knee helps improve stability and relieve joint pressure.

  • Weight management: Reducing excess body weight decreases the load on the knees and can lessen pain significantly.

  • Medications and injections: Anti-inflammatory drugs, corticosteroid injections, or hyaluronic acid can temporarily ease symptoms.

  • Bracing and activity modification: Using a knee brace or adjusting certain movements can help protect the joint and minimize irritation.

While these measures can provide meaningful relief, they may become less effective as arthritis progresses.

Knee Replacement Surgery

When knee arthritis becomes severe and pain or stiffness limits daily activity, total knee replacement surgery may be considered. In this procedure, the damaged bone and cartilage are removed and replaced with artificial components that mimic the natural joint.

Knee replacement surgery is highly successful in reducing pain and improving mobility, but it requires a significant recovery period and rehabilitation. For patients who wish to avoid or delay surgery—or for those who are not ideal surgical candidates—newer, less invasive options are now available.

ONSTIM: A Minimally Invasive Option for Knee Pain Relief

ONSTIM is an innovative treatment designed to relieve chronic knee pain without removing or replacing the joint. It uses a small implantable system that targets the nerves responsible for sending pain signals from the knee to the brain. By gently stimulating these nerves, ONSTIM helps block pain messages before they reach the central nervous system.

The procedure is minimally invasive and typically performed as an outpatient treatment. Unlike knee replacement surgery, it does not involve removing bone or cartilage. The system is designed to provide meaningful pain relief and improve function, allowing patients to walk, exercise, and participate more fully in daily life.

Many patients who have tried physical therapy, medications, or injections without success find ONSTIM to be a helpful bridge between conservative care and surgical intervention. It offers the potential to delay or even avoid knee replacement while still addressing chronic knee pain at its source.

A New Path Forward

Knee arthritis can be life-changing, making simple movements painful and limiting independence. Fortunately, treatment options are evolving. While traditional approaches such as exercise, injections, and surgery remain important, ONSTIM offers a new, non-destructive way to manage knee pain.

For individuals seeking long-term relief without the downtime or risks associated with major surgery, ONSTIM may represent an exciting and effective option. Patients should discuss their symptoms and treatment history with a qualified orthopedic or pain management specialist to determine whether this innovative therapy could be the right solution for their chronic knee pain.