Osteoarthritis of the knee (knee OA) is the inflammation and degeneration of the bones that form the knee joint (osteo=bone, arthro=joint, itis=inflammation). The diagnosis of knee OA is based on 2 primary findings: radiographic evidence of changes in bone health (through medical images such as x-ray and MRI) and an individual’s symptoms (how you feel). Approximately 14% of adults aged 25+ and 34% of adults aged 65+ are diagnosed with radiographic osteoarthritis. Specifically, about 16% of adults aged 45+ have knee OA.
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What is Osteoarthritis of Knee?
Osteoarthritis of the knee (knee OA) is a progressive disease causing inflammation and degeneration of the knee joint that worsens over time. It affects the entire joint, including bone, cartilage, ligament, and muscle. Its progression is influenced by age, body mass index (BMI), bone structure, genetics, strength, and activity level. Knee OA also may develop as a secondary condition following a traumatic knee injury. Depending on the stage of the disease and whether there are associated injuries or conditions, knee OA can be managed with physical therapy. More severe or advanced cases may require surgery.
How Does it Feel?
Individuals who develop knee OA experience a wide range of symptoms based on the progression of the disease. Pain occurs when the cartilage covering the bones of the knee joint wears down. This narrows the space between the bones and causes friction. Because the knee is a weight-bearing joint, your activity level, and the type and duration of your activities usually have a direct impact on your symptoms.
Symptoms of knee OA may include:
- Worsening pain during or following activity, particularly with walking, climbing, or descending stairs, or moving from a sitting to standing position
- Pain or stiffness after sitting with the knee bent or straight for a prolonged period of time
- A feeling of popping, cracking, or grinding when moving the knee
- Swelling following activity
- Tenderness to touch along the knee joint
Typically these symptoms do not occur suddenly or all at once, but instead they develop gradually over time. Sometimes individuals do not recognize they have osteoarthritis because they cannot remember a specific time or injury that caused their symptoms. If you have had worsening knee pain for several months that is not responding to rest, it is best to seek the advice of a medical provider.
How Is It Diagnosed?
Knee OA is diagnosed by 2 primary methods. The first is based on your symptoms and a clinical examination. Your physical therapist will ask you questions about your medical history and activity routine. He or she will perform a physical exam to measure your knee’s movement (range of motion), strength, mobility, and flexibility. You might also be asked to perform various movements to provoke the pain you are experiencing.
The second tool used to diagnose knee OA is diagnostic imaging. Your physical therapist may refer you to a physician, who will order x-rays of the knee in a variety of positions to assess the effect of weight-bearing (walking, standing, etc) on your knee joint. If more severe joint damage is suspected, an MRI may be ordered to look more closely at the overall status of the joint and surrounding tissues.
How Can a Physical Therapist Help?
Your physical therapist will design an individualized treatment program specific to the exact nature of your condition and your goals.
Range of Motion
Often, abnormal motion of the knee joint can lead to a progression of OA when there is more contact between, and wear on, the bones. Your therapist will assess your motion compared with expected normal motion and the motion of the knee on your uninvolved leg.
Strengthening the muscles around your knee will be an essential part of your rehabilitation program. Individuals with OA who adhere to strengthening programs have been shown to have less pain and an improved overall quality of life. There are several factors that influence the health of a joint: the quality of the cartilage that lines the bones, the tissue within and around the joints, and the associated muscles. Due to the wear and tear on cartilage associated with knee OA, maintaining strength in the muscles near the joint is crucial to preserve joint health. For example, as the muscles along the front and back of your thigh (quadriceps and hamstrings), cross the knee joint, they help control the motion and forces that are applied to the bones.
Strengthening the hip and core muscles also can help balance the amount of force on the knee joint, particularly during walking or running. The “core” refers to the muscles of the abdomen, low back, and pelvis. A strong core will increase stability through your body as you move your arms and legs. Your physical therapist will assess these different muscle groups, compare the strength in each limb, and prescribe specific exercises to target your areas of weakness.
Physical therapists are trained in manual (hands-on) therapy. Your physical therapist will gently move and mobilize your muscles and joints to improve their motion, flexibility, and strength. These techniques can target areas that are difficult to treat on your own. In patients with knee OA, the addition of manual therapy techniques to exercise has been shown to decrease pain and increase function.
Your physical therapist may recommend therapeutic modalities, such as ice and heat, to aid in pain management.
Compressive sleeves placed around the knee may help reduce pain and swelling. Devices such as realignment braces are used to modify the forces placed on the knee. These braces can help “unload” certain areas of your knee and move contact to less painful areas of the joint during weight-bearing activities.
Physical therapists are trained to understand how to prescribe exercises to individuals with injuries or pain. Since OA is a progressive disease, it is important to develop a specific plan to perform enough activity to address the problem while avoiding increases in stress on the knee joint. Activity must be prescribed and monitored based on type, frequency, duration, and intensity, with adequate time allotted for rest and recovery. Your physical therapist will consider the stage and extent of your arthritis and prescribe an individualized exercise program to address your needs and maximize the function of your knee.
What if I Need Surgery?
In some cases of knee OA, the meniscus (shock absorber of the knee) may be involved. In the past, surgery to repair or remove parts or all of this cartilage was common. Current research, however, has shown in a group of patients who were deemed surgical candidates, 60-70% of those who participated in a physical therapy program, instead of surgery, did not go on to have surgery. Further, after 1 year those outcomes were unchanged. This study suggests that physical therapy may be an effective alternative for those patients who would like to avoid surgery.
Sometimes conservative management strategies are not successful. When these strategies fail surgical intervention such as arthroscopy or a total knee replacement, may be recommended. There are many factors to consider when determining the appropriate surgical treatment, including the nature of your condition, and your age, activity level, and overall health. Your physical therapist will refer you to an orthopedic surgeon to discuss your surgical options.