The knee is the largest joint in the body, making it vulnerable to many problems. Being aware of these problems and how to prevent them can help keep your knees healthy throughout your life, says Frederick Song, MD, an orthopedist on staff at University Medical Center at Princeton (UMCP).

Overuse injuries: In young athletes, overuse injuries are increasingly common, including patellofemoral syndrome, a dull pain caused by irritation under the knee cap. These injuries are often caused by playing the same sport year-round, weakening muscles that protect the knee. Playing different sports during different times of the year can help prevent injuries by working different muscle groups. “The number one way to treat overuse injuries is to temporarily stop playing that sport and work on a supervised strengthening program.” Dr. Song says. “It’s hard for parents and athletes to commit to stopping, but it can prevent more serious problems.”

Traumatic injuries: Sudden injuries from acute deceleration or cutting with or without contact are common in youth athletes and young- and middle-aged adults. These injuries include ligament tears and tears of the meniscus, the fibrocartilage that acts as a shock absorber between knee bones. Adults who participate in sports should also vary their activities and perform exercises to strengthen the hamstrings and quadriceps — muscles that support the knee. Keeping your core muscles strong is also essential for injury prevention. For tears, treatment usually involves surgery to remove or repair the damaged meniscus or reconstruct the ligament.

Degenerative injuries: In adults over 50, the most common knee problem is osteoarthritis, the gradual breakdown, and loss of cartilage. It’s challenging to prevent arthritis, but keeping your weight down, strengthening the muscles surrounding the knee, and focusing on low-impact exercises such as swimming and biking can help. Osteoarthritis is first treated conservatively with physical therapy and anti-inflammatory medication. Second-line treatments include injections to reduce pain or improve lubrication in the knee. “If a patient exhausts all of those treatments and continues to have pain that affects their daily activity,” Dr. Song says, “then we discuss knee replacement.”

When to see a doctor

Sudden pain and swelling due to injury should be evaluated as soon as possible. Swelling that comes on gradually, and doesn’t improve in a matter of days with rest and ice, should also be brought to your doctor’s attention.