If you have painful knees, you may think it’s arthritis.

While arthritis is a common cause of knee pain, there may be another reason for your aches, said Dr. Maya Battikha, a physical medicine and rehabilitation physician.

These four conditions are often associated with knee pain. If you suspect you have one of these problems, talk to your doctor about diagnosis and treatment.

Osteoarthritis

Osteoarthritis is the most common type of arthritis and the most common knee issue in older adults. It’s caused by wear and tear to any of the three compartments in your knees.

Symptoms:

• Pain
• Stiffness
• Intermittent swelling
• Crunching or grinding sounds, called crepitus, in your knees

You may have symptoms on the insides or outsides of your knees or under your kneecaps, depending which compartments are affected.

Treatment:

Ice or heat and anti-inflammatory medications are the most common treatments.

Range of motion exercises, biking, swimming and the elliptical are good low impact options to strengthen quadriceps, hips and core muscles that support your knees.

“Any time you have a sore area, the body tries to protect it by telling the muscles in that area not to work well,” Battikha said. “The solution is to re-train those muscles to work more efficiently to control the knee joint.”

If your knees still ache, talk to your doctor about other treatments.

Patellofemoral pain syndrome

Patellofemoral pain syndrome is the most common cause of knee pain in younger people. It occurs when the kneecaps don’t track properly in their grooves due to muscle imbalances.

Symptoms:

• Subtle swelling
• Stiffness when sitting or immediately after getting up from a seated position
• Pain around the kneecaps and in front of the knees, especially when walking down stairs

Treatment:

Ice, anti-inflammatory medications and a brace with a ridge that keeps the kneecap in place can help.

Try biking and balance exercises to strengthen your core, quadriceps, hips and knees.

When bending or squatting, don’t let your knees extend past your toes or cave in to a knock-kneed position.

Meniscal tears

Falls, twisting accidents and degeneration can tear the c-shaped cushions, called meniscuses, around your knees.

Symptoms:

• Pain when you twist or pivot at the knees
• Swelling and stiffness if the tear was caused by a fall or accident
• Pain similar to osteoarthritis if the tear is degenerative

Treatment:

Meniscal tears can be surgically repaired for patients in their teens and 20s, but repair is unlikely to help people older than 30, Battikha said. Meniscal tears in older people are most often treated conservatively with range of motion exercises, strengthening regimens and ice.

If conservative care doesn’t help, trimming the tear’s frayed edges may prevent locking or catching of the knee joint.

Baker’s cyst

A Baker’s cyst forms when fluid from the knee joint builds up in a pouch behind your knee. It’s a common consequence of knee injuries.

Symptoms:

The cyst typically doesn’t cause any pain. Pain that accompanies a Baker’s cyst usually is caused by other knee problems.

“Rarely, the cyst ruptures and causes the sensation of warm water running down your calf,” Battikha said. “There’s no reason to worry if that happens.”

Treatment:

Removing or draining the cyst normally doesn’t help knee pain. Treating the underlying knee problem will relieve pain.