What Are the Risk Factors for Knee Osteoarthritis?

Risk factors for knee osteoarthritis include increasing age, previous knee injury or surgery, repeated heavy loading, higher body weight, altered leg alignment, muscle weakness, and family history. Having one or more of these factors does not mean that osteoarthritis will develop, and people can develop knee pain without having the condition.

The knee is a load-bearing joint in which cartilage, bone, muscles, tendons and ligaments work together. With age, the joint may become less able to tolerate repeated stress. An earlier injury, such as an ACL tear or meniscus tear, can change stability or how force moves through the knee even after the initial injury has healed. Surgery may also alter joint mechanics.

Activities involving frequent kneeling, squatting, lifting, running, jumping or climbing can add repeated loading, especially when recovery is limited. Higher body weight increases the force the knee manages during movement. Bow-legged or knock-kneed alignment can concentrate pressure on part of the joint. Weakness around the thigh, hip or trunk may reduce control during walking and stairs. Genes, joint shape and family history can also influence susceptibility.

Some factors cannot be changed, but knee function can often be supported. Build activity gradually, alternate demanding tasks with recovery, and use strength exercises for the quadriceps, hamstrings, hips and core when suitable. Low-impact options such as cycling, swimming or walking on level ground may be easier to tolerate than repeated jumping. A physiotherapist can adapt exercises if pain, an old injury or alignment makes a movement difficult. If body weight is affecting symptoms, a clinician can help set a realistic, joint-friendly plan without focusing on a quick change.

Arrange an assessment if knee pain, stiffness or swelling keeps returning, limits stairs or walking, disturbs sleep, or follows an injury. Seek prompt care after a significant injury if you cannot bear weight, the knee looks deformed, or it repeatedly gives way or locks. A hot, red, markedly swollen knee with fever also needs urgent medical assessment because infection or another acute problem can resemble arthritis.

Ask which factors are most relevant in your history, whether an old ligament or meniscus injury has changed knee mechanics, and which activities should be modified temporarily. You can also ask how strength, flexibility and leg alignment will be assessed, whether imaging would change management, and how to progress exercise without provoking a flare.