The knee is the most commonly injured joint in the body. Knee pain can arise from multiple causes.
A knee sprain may be associated with twisting or bending the knee inappropriately. Usually, no imaging is required to diagnose a mild to moderate knee sprain. In more severe cases, ultrasound or MRI may be needed to diagnoses a completely torn knee ligament such as a ruptured ACL. A less severe knee sprain will typically heal in a few weeks with conservative management including rest, ice, NSAIDs, and physical therapy. Sometimes a brace may also be used to help stabilize the knee or reduce painful swelling while it heals.
Knee arthritis is extremely common as we age. In the average person, arthritis begins in our fifties and progresses as we get older. Knee replacement is a common surgery that is typically performed in our sixties or seventies once the arthritis has progressed to being more severe. This is around the time you may hear the phrase “bone on bone” arthritis be uttered. At first, the arthritis presents as narrowing on one side of the joint. This results in uneven wearing of the joint as the cartilage begins to disappear. In order to protect the joint, the body begins laying down new bone. This new bone is termed osteophytes. After this happens and if the joint continues to wear out, then the bones within the joint may start to develop subchondral cysts and sclerosis. This basically means the bones are starting to be damaged. At this point, there will typically be no cartilage left within the joint to cushion and protect the bone so a knee replacement surgery is needed to decrease pain.
Prior to needing a knee replacement surgery, however, there are more conservative treatment options that may be utilized. Initially, NSAIDs, icing, physical therapy, and bracing should be attempted. If pain recurs or persists, then injections should be attempted. These include corticosteroid injections at first at later hyaluronic acid injections possibly. Hyaluronic acid is basically joint fluid that can be injected every so often to help lubricate and cushion the joint. Typically these are performed at 6 or 12 month intervals and can be repeated regularly as they are very safe. Steroids can also be repeated if needed, however, they can be toxic to the joint if performed too often.
New treatment options have been developed over the past decade or so that can help you decrease your knee pain and possibly even avoid needing surgery. These treatments are known as Regenerative Medicine and include Platelet-Rich Plasma (PRP) or Stem Cell Therapy. Platelets from your own blood or stem cells from your own body are taken and then prepared for injection back into the site of the injury. There is promising new research showing the benefits of PRP and stem cells for knee arthritis. These cutting-edge treatments offer patients additional options to heal and feel better if they have failed conservative treatment and cannot tolerate surgery or would prefer to avoid it.
Another type of knee pain is a meniscus injury. Each knee has two menisci, one on the inside part of the knee (medial) and one on the outside (lateral). Menisci are cartilage rings that sit on top of the tibia, which is the lower leg bone that forms the bottom of the knee joint. These cartilage rings help provide cushioning to the knee joint. It is possible for one to develop a torn meniscus by bending or twisting the knee incorrectly. Sometimes a pop or click can be heard at the onset of the injury. Swelling and pain may develop over the next few days. (A pop or click can also be heard with a ligament tear such as in an ACL injury, so it is important to be evaluated by a physician as soon as possible if this happens to you.)
A torn meniscus is usually diagnosed with MRI if surgery is going to be considered. Depending on how active the injured person is, how old they are at the time of the injury, and what part of the meniscus is damaged will help to determine if surgery is recommended or not. Often times, more conservative management including physical therapy, NSAIDs, and bracing may be enough to allow the meniscus to heal on its own over time. If surgery is indicated, a minimally invasive arthroscopic surgery can typically be performed.
Sometimes, the fluid from the knee joint spills out into the back of the knee and forms a cyst, or fluid-filled pocket. This can cause painful swelling and pressure in the back of the knee. This condition is best diagnosed with ultrasound or MRI. The fluid in a Baker's cyst can be drained out to help reduce the pressure and pain it causes.
Patellofemoral syndrome (PFS) is another common cause of knee pain. Normally, the patella (knee cap) slides straight up and down within the knee joint. If the knee cap does not slide in its normal groove, then it is possible to develop pain. This condition is termed PFS. The pain in PFS is typically located around the knee cap. It is often made worse when bending the knee which puts additional stress on the patella. The normal tracking of the patella is stabilized by the quadriceps muscles which are located on the front of the thigh. If the middle quadriceps muscle called the vastus medialis oblique (VMO) is weak, then the knee cap will often slide to the outside of the knee. This inappropriate tracking eventually results in pain.
No imaging is required to diagnose PFS. Sometimes x-ray or MRI may reveal damage to the back of the knee cap from poor tracking as detailed above. A grinding sensation may be felt behind the knee cap because of this, as well.
To correct this problem it’s crucial to strengthen the VMO, thus encouraging normal tracking of the patella. Knee braces that help the patella track correctly can also be used. Ice and NSAIDs can help reduce pain while rehabbing the injury.
Iliotibial Band Syndrome
Iliotibial band (ITB) syndrome is another common cause of knee pain. The pain in ITB syndrome usually develops on the outside and upper portion of the knee. The iliotibial band is a thick band of fibrous tissue that runs along the outside of the thigh and connects down by the knee. If the ITB is tight, it can affect the normal function of the knee and cause pain.
Diagnosing ITB syndrome does not require any imaging. Localized pain and a tight ITB on physical exam help make the diagnosis.
ITB syndrome is treated with physical therapy. Aggressive stretching of the muscles in the thigh that attach to the ITB is a major component of rehabbing this injury. Often, a foam roll will be used to help massage the ITB. Loosening up the ITB will help restore normal function of the knee joint. Ice, heat, and NSAIDs can help reduce the pain from ITB syndrome while rehabbing it. Rarely, a steroid injection to the ITB can help reduce pain associated with this condition.