Studies suggest knee ligament damage may lead to osteoarthritis

ASK THE DOCTORS By Eve Glazier, M.D., and Elizabeth Ko, M.D.

Dear Doctor: I tore my knee ligament playing soccer a month ago and my cousin, who had the same injury but from snowboarding, says that means I’ll get arthritis in the next few years. Is he right, even though I’m only 23?

Dear Reader: We’re sorry to learn of your injury and wish we were about to give you better news. While things aren’t quite as inevitable as your cousin has outlined, the truth is that he’s in the ballpark. Research suggests that about half of all individuals who suffer an injury to the ligaments of the knee, no matter their age, go on to develop osteoarthritis within the next 10 years. It’s one of the reasons why, when parents focus on concussion in discussions about their kids playing sports, we always make sure to broach the subject of knee injuries as well.

The knee is the largest joint in the body. It’s basically a hinge at the point where the thigh bone, or femur, meets the tibia, which is the larger bone in your shin. The kneecap, or patella, protects the front of the joint. Keeping all of these moving parts connected, yet stable and flexible, is a joint capsule interlaced with a series of ligaments. The ligaments provide stability, limit rotation and sideways motion of the knee, and allow it to flex and extend within a set range of motion. Injuries occur when falls, jumps, shifts of weight or pressure from an outside source, like a tackle, stress the joint beyond what the ligaments can bear.

The anterior cruciate ligament, or ACL, is the workhorse of knee stability. As a result, ACL injuries are common in sports like soccer, football, basketball, snowboarding or skiing, where participants are constantly leaping, whirling or shifting their weight, often at high speed. Physical therapy and surgery can restore stability and get individuals with knee ligament injuries back on their feet.

However, studies that followed these patients over the course of a decade found that about half went on to develop arthritis. The reasons for this aren’t fully understood. Some research has identified the ongoing presence within the knee of tiny proteins associated with inflammation, which persist long after the joint has been repaired. This suggests that the subsequent osteoarthritis has a biochemical component. Another school of thought is that, despite repair and rehabilitation, the knee joint just isn’t the same and new stresses lead to deterioration over time.

If at any point you begin to experience the following symptoms, it’s important that you check in with your doctor. These include:

— Stiffness in the joint, particularly in the morning, or after a period of inactivity

— A decrease in knee mobility that interferes with daily activity

— Knee pain associated with activity that abates when you rest

— Swelling or a feeling of warmth in the joint

— Sounds when the knee moves, like creaking or crackling

We hope you sought medical care for your injury. Whether you consider surgery, physical therapy or a combination of the two, please be vigilant about following your medical team’s instructions.

Eve Glazier, M.D., MBA, is an internist and assistant professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and primary care physician at UCLA Health.