Knee pain is very common and is usually caused by minor injuries or overuse. Most cases of knee pain are not serious and can be treated at home with rest, ice, compression, and elevation. However, some types of knee pain can indicate more serious injuries or conditions that require medical attention.
How can you tell if knee pain is serious?
Some signs that knee pain may be serious and require prompt medical care include:
- Inability to bear weight or walk
- Locking or buckling of the knee
- Swelling that does not improve with rest and ice
- Pain accompanied by numbness or weakness
- Intense pain that worsens at night or while resting
- Knee pain after a forceful trauma like a fall or car accident
- Signs of infection like warmth, redness, fever
If your knee pain is severe, comes on suddenly, or is accompanied by any of these warning signs, it’s important to see a doctor for proper diagnosis and treatment. Leaving serious knee injuries or conditions untreated can lead to complications or permanent damage.
What causes serious knee pain?
Some potential causes of serious knee pain that require medical care include:
Knee injuries
- Torn ligaments – such as the anterior cruciate ligament (ACL) or medial collateral ligament (MCL). A popping sensation and instability of the knee joint are common with ligament tears.
- Torn meniscus – injury to the cartilage pads that act as shock absorbers in the knee. Locking, catching, or popping sensations with knee movement can occur.
- Patellar dislocation – dislocation of the kneecap. Immediate knee swelling and inability to straighten the knee are typical.
- Fractures – breaks in any of the bones surrounding the knee like the patella, femur, tibia, or fibula. Cause severe pain and inability to bear weight.
Knee conditions
- Osteoarthritis – degenerative joint disease causing progressive knee cartilage damage. Leads to pain, swelling, and stiffness, especially with activity.
- Rheumatoid arthritis – inflammatory arthritis that commonly affects the knees. Causes painful swelling and tenderness.
- Septic arthritis – joint infection causing intense knee pain, swelling, warmth and redness. Fever is usually present.
- Gout – uric acid crystals depositing in the joints, often the knees. Very painful swelling occurs in episodic attacks.
- Pseudogout – similar to gout but with calcium pyrophosphate crystals depositing in joints.
Other causes
- Baker’s cyst – fluid-filled cyst behind the knee that can rupture and cause pain and swelling.
- Bone tumor – benign or malignant tumors of the knee bones. Cause progressive knee pain.
- Referred pain – pain from nerve compression in the back, hip or foot radiating to the knee area.
When to see a doctor for knee pain
You should seek prompt medical attention if you have:
- Sudden, severe knee pain or swelling after an injury
- Knee pain accompanied by numbness, weakness, instability or inability to bear weight
- Intense or worsening knee pain, especially at night
- Signs of infection like warmth, redness, fever
- Locking, clicking or popping in the knee joint
- Swelling and pain after a minor knee injury that does not improve with R.I.C.E. treatment
It’s also a good idea to see a doctor for mild but persistent knee pain lasting more than a week that limits your activity and does not respond to home treatment. Chronic knee pain can signal arthritis or other problems that need medical care to prevent further damage.
Diagnosing the cause of knee pain
To determine the underlying cause of knee pain, the doctor will begin with a medical history and physical exam of the knee. They may check range of motion, stability, alignment, swelling and look for areas of tenderness.
Some tests that can help diagnose knee problems include:
- X-ray – helps detect fractures, arthritis, and bone tumors.
- MRI – gives detailed images of ligaments, tendons, cartilage and other soft tissues around the knee.
- CT scan – provides cross-sectional views of bones and tissues.
- Arthrocentesis – inserts a needle into the knee joint to remove fluid for analysis.
- Arthroscopy – inserts a fiberoptic camera into the knee for direct visualization of damage.
Based on your symptoms, medical history and exam findings, your doctor will determine what imaging tests or procedures will be needed to make an accurate diagnosis.
Serious knee conditions that require treatment
Some examples of serious knee disorders that require prompt medical treatment include:
Torn ACL
The anterior cruciate ligament runs diagonally through the knee joint providing stability. An ACL tear causes pain, instability and often a “popping” sound. It will not heal without surgery. Treatment involves either reconstructive surgery or physical therapy to regain strength and function.
Meniscal tear
The menisci are c-shaped discs of cartilage that cushion the knee. Twisting injuries can tear the meniscus causing pain, catching, swelling and limited motion. Small tears may heal with rest and physical therapy. Larger tears require arthroscopic surgery to repair or remove the damaged cartilage.
Fractures
Breaks in the bones around the knee like the distal femur, proximal tibia, patella or fibula require prompt medical attention. Treatment depends on the location and severity of the fracture. It may involve casting, surgery with pins/plates, or external fixation.
Septic arthritis
This serious knee infection requires hospitalization for intravenous antibiotics. The joint is drained of infected fluid and the antibiotics kill the bacteria. Prompt treatment is needed to prevent permanent joint damage.
Rheumatoid arthritis
There is no cure for rheumatoid arthritis, an autoimmune disorder causing knee inflammation and destruction. Early, aggressive treatment with DMARDs, biologics, and other medications can relieve pain and swelling and help preserve joint function.
Nonsurgical treatments for knee pain
For mild to moderate knee pain, your doctor may recommend trying:
- Rest and avoiding activities that aggravate the knee
- Ice packs to reduce swelling
- Compression bandage to limit swelling
- Elevation of the leg above heart level
- Pain relievers like NSAIDs (ibuprofen, naproxen)
- Physical therapy exercises to strengthen muscles around the knee
- Bracing or taping the knee for stability
- Shoe orthotics
- Corticosteroid injections for arthritis pain
- Viscosupplementation injections to improve arthritis knee lubrication
If these conservative measures do not adequately relieve pain and improve function, surgery may be needed.
Knee surgery procedures
Common knee surgery procedures to treat serious knee injuries, arthritis, or overuse damage include:
- Arthroscopy – repairs torn meniscus cartilage, removes loose fragments, or smoothes arthritic cartilage damage.
- ACL reconstruction – grafts a replacement ACL ligament using a tendon from the hamstring or patella.
- Osteotomy – realigns angled joints affected by arthritis to help distribute weight properly.
- Joint replacement – removes damaged sections of bone and cartilage and implants artificial components.
- Cartilage grafting – transplants healthy cartilage to repair defects and injury sites.
Proper rehabilitation after surgery with physical therapy is key to regaining strength and knee function.
Preventing knee pain and injury
You can help protect your knees and prevent pain and injury through actions like:
- Maintaining a healthy weight to avoid overloading the joints
- Wearing supportive and well-cushioned shoes
- Using proper technique and gear when exercising or playing sports
- Strengthening the leg, hip and core muscles through exercise
- Avoiding high-impact activities on hard surfaces
- Warming up and stretching before physical activity
- Replacing worn out athletic shoes regularly
Bracing vulnerable knees during sports can also prevent injury in some cases. Listen to your body and if knee pain persists, gets worse, or causes concern, seek medical care promptly. Catching and addressing problems early maximizes the chances of a good recovery.
Conclusion
Most minor knee pain can be managed with R.I.C.E. therapy and over-the-counter medications. However, severe, worsening, or persistent knee pain should not be ignored as it may indicate a serious injury or condition requiring medical care. Warning signs to watch for include inability to bear weight, locking/buckling, swelling, numbness and trauma. See a doctor right away if you have these types of knee symptoms for proper diagnosis and timely treatment.