Top Reasons To Have Sudden Knee Pain Without Injury

sudden knee pain, white male holding knee

If you’re experiencing sudden knee pain without any known injury, it can be quite distressing. You may wonder what could be causing the pain and how to find relief.

While there are numerous potential causes, exploring the most common ones is important to understand your condition better. Then you can take the necessary steps to manage your knee pain effectively.

Common Causes of Sudden Knee Pain

When knee pain occurs without a specific injury, several factors can be responsible. Understanding these causes can help identify and treat the underlying issue.

Arthritis: Arthritis is a common cause of knee pain, especially in older adults. Osteoarthritis, the most common form of arthritis, occurs when the protective cartilage in the knee joint wears down over time. This can lead to pain, stiffness, and swelling in the knee.

Knee Fracture: A knee fracture refers to a break or crack in one or more of the bones that make up the knee joint. This can occur due to a fall, direct impact, or a high-force trauma. Knee fractures can cause severe pain, swelling, and difficulty in moving the knee.

Knee Tendinitis: Tendinitis is the inflammation of a tendon, which is the tissue that connects muscles to bones. Knee tendinitis commonly affects the patellar tendon, which connects the kneecap to the shinbone. This condition can cause pain, tenderness, and swelling in the front of the knee.

Runner’s Knee: Runner’s knee, also known as patellofemoral pain syndrome, is a common condition among athletes, especially runners. It occurs when the cartilage on the underside of the kneecap becomes irritated or worn down. This can result in pain around or behind the kneecap, especially during activities that involve bending the knee.

Torn Ligament: A torn ligament in the knee, such as the anterior cruciate ligament (ACL) or the medial collateral ligament (MCL), can cause sudden and severe knee pain. Ligament tears often occur during sports activities involving sudden stops, direction changes, or direct blows to the knee.

Bursitis: Bursitis is the inflammation of the bursae, small fluid-filled sacs that cushion the bones, tendons, and muscles near the joints. When the bursae in the knee become inflamed, it can cause pain, swelling, and tenderness in the affected area.

Injured Meniscus: The meniscus is a C-shaped piece of cartilage that acts as a shock absorber between the thighbone and shinbone. An injured meniscus can occur due to a sudden twist or rotation of the knee, causing pain, swelling, and difficulty in fully extending or bending the knee.

Gout: Gout is a form of arthritis that occurs when uric acid crystals build up in joints, including the knee joint. This can result in sudden and intense pain, swelling, redness, and warmth in the affected area.

Infectious Arthritis: Infectious arthritis, also known as septic arthritis, is a bacterial or fungal infection in the joint. When the knee joint becomes infected, it can cause severe pain, swelling, redness, and warmth. Prompt medical attention is necessary to treat the infection and prevent further complications.

These are just a few of the common causes of sudden knee pain. It is important to consult with a healthcare professional for an accurate diagnosis and appropriate treatment based on the specific symptoms and underlying cause of the knee pain.

Knee Pain Caused by Arthritis

Arthritis is one of the leading causes of knee pain, especially among older individuals. The two most common types are osteoarthritis and rheumatoid arthritis.

Osteoarthritis is a degenerative condition that affects the cartilage in the knee joint, causing pain and stiffness. Rheumatoid arthritis, on the other hand, is an autoimmune disease that leads to chronic inflammation of the joints, resulting in swelling and discomfort.

While arthritis may be a chronic condition, many non-surgical methods exist to relieve knee pain. Exercise and physical therapy can strengthen the muscles surrounding the knee joint, reducing pressure on the affected area.

Additionally, weight management is crucial to alleviate extra strain on the knees. Wearing supportive shoes and using assistive devices, such as knee braces or canes, can also provide relief.

Knee Fracture

Although less common, a knee fracture can cause sudden knee pain without a known injury. Fractures can occur due to accidents, falls, or stress on the knee joint. If you suspect a fracture, it’s important to seek medical attention immediately.

Treatment usually involves immobilization through a cast or splint, and sometimes surgical intervention may be necessary.

Knee Tendinitis

Knee tendinitis, also known as patellar tendinitis or jumper’s knee, is a common overuse injury that affects the tendons surrounding the knee. Repetitive strain, such as jumping or running, can lead to inflammation and pain in the tendon.

Rest, ice, and physical therapy are often recommended to ease symptoms. Avoiding activities that exacerbate the pain and gradually returning to exercise can help prevent future episodes.

Runner’s Knee

Runner’s knee, or patellofemoral pain syndrome, is a condition characterized by pain in the front of the knee. It often occurs due to improper alignment of the kneecap or overuse of the knee joint. Engaging in activities that involve repetitive knee bending, such as running or cycling, can contribute to this condition.

Rest, ice, and physical therapy are effective treatment options. Strengthening the muscles around the knee and using supportive braces can also provide relief.

Torn Ligament

A torn ligament, such as an ACL (anterior cruciate ligament) tear, can cause sudden knee pain and instability. This injury commonly occurs during sports or activities that involve sudden changes in direction or pivoting.

Treatment options for ligament tears vary depending on the severity of the injury. Physical therapy, bracing, and sometimes surgical repair may be necessary.


Bursitis refers to inflammation of the bursae, which are small fluid-filled sacs that provide cushioning between bones, tendons, and muscles. Knee bursitis often results from repetitive pressure or trauma.

Rest and the application of ice or heat can help reduce pain and inflammation. If the condition persists, a healthcare professional may recommend other treatments, such as physical therapy or corticosteroid injections.

Injured Meniscus

An injured meniscus, which is a piece of cartilage in the knee joint, can cause sudden knee pain. It often occurs due to twisting or over-flexing of the knee joint.

Symptoms may include pain, swelling, and difficulty bending the knee. Physical therapy and strengthening exercises can help manage symptoms, while severe cases may require surgical intervention.


Gout is a form of arthritis that typically affects the big toe joint. However, it can also cause sudden knee pain. Gout is characterized by an accumulation of uric acid crystals in the joint, leading to inflammation and severe discomfort.

Medications, lifestyle changes, and dietary modifications can help manage gout and prevent recurrent flares.

Infectious Arthritis

Infectious arthritis, also known as septic arthritis, occurs when bacteria or other infectious organisms enter the joint space. It can cause sudden knee pain, along with redness, swelling, and warmth around the joint.

Immediate medical attention is crucial to prevent further joint damage. Treatment may involve antibiotics and drainage of the infected fluid from the affected joint.

If you’re experiencing sudden knee pain without a known injury, it’s important to consult a healthcare professional for an accurate diagnosis. They can evaluate your symptoms, conduct any necessary tests, and recommend appropriate treatment options. Remember, early intervention and non-surgical methods are often effective in managing knee pain and improving your quality of life.

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Our expert physicians utilize advanced digital imaging to accurately deliver FDA-approved viscosupplementation gel injections, helping you get back to the activities you love with minimal downtime. Don’t let knee pain control your life. Schedule Your No-Charge Screening today and take the first step towards a more active and comfortable future.

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