What is Suprapatellar Joint Effusion?
Suprapatellar joint effusion is painful and usually affects knee joint movement. Knee effusion is also commonly termed as water on the knee. Suprapatellar joint effusion is the accumulation of fluid in the suprapatellar or the upper region of the knee joint.1 Suprapatellar joint effusion is one of the commonest causes of knee joint pain and must be treated to prevent further complications.
Suprapatellar joint effusion, in which the knee swells up due to fluid accumulation in the suprapatellar region. While some fluid is present in the knee joint for normal lubrication, excess accumulation of fluid can be a problem. Hence, it is important to know the causes of suprapatellar joint effusion and treat accordingly. Knowing the symptoms of suprapatellar joint effusion can help in seeking timely medical advice.
Causes of Suprapatellar Joint Effusion
Suprapatellar joint effusion can be a result of various conditions ranging from injuries, infections to joint problems and other medical conditions.
Some of the commonest causes of suprapatellar joint effusion include the following.
Injuries – Injuries are one of the most important causes of suprapatellar joint effusion or knee swelling. Meniscus injury or cartilage tear, ligament injury of the knee joint are some of the commonest knee injuries. Fractures, overuse injuries or repetitive stress injuries are one of the other causes of suprapatellar joint effusion.
Joint Conditions – Conditions like arthritis, which cause wear and tear of the joint, result in loss of cartilage. For example, osteoarthritis, which is a degenerative condition, is one of the other common causes of suprapatellar joint effusion. In this, the knee symptoms may be present to some extent in both the knees, however, suprapatellar effusion may be prominently noted in any one knee. Inflammatory conditions like rheumatoid arthritis, too are one of the major causes of suprapatellar joint effusion. In rheumatoid arthritis, knee swelling is often seen on both sides and small joints of hands are more affected. Other autoimmune disorders like lupus too can severely affect the knee joint. Joint conditions like gout and pseudo gout, prepatellar bursitis, can also cause suprapatellar joint effusion.
Infections – Infections are other major causes of suprapatellar joint effusion. Sudden, large suprapatellar joint effusion, on one side with fever usually arises the suspicion of infectious causes; infective or septic arthritis being the commonest. Other infections that affect the bones and joint must also be evaluated. Tuberculosis, primarily an infection of the lung or other bacterial infections too can cause suprapatellar joint effusion.
Other Conditions – Inflammatory conditions too can affect the knee joint and cause suprapatellar joint effusion. Cysts, tumors or cancers of the bone or cancer spread from other areas are also some of the causes of suprapatellar joint effusion. Lyme disease or some rare diseases can also cause suprapatellar joint effusion.
While water on knee can be seen in anyone, certain risk factors of suprapatellar joint effusion include
Aging – Aging causes degenerative changes, weakening of muscles and increases the risk of joint problems.
Being Overweight – As knee is a weight bearing joint, people who are overweight or obese can experience pain and swelling in knee. If there are any existing causes of suprapatellar joint effusion, like osteoarthritis, rheumatoid arthritis or any other joint conditions, increase in weight can add to the problems.
Injuries – People who have experienced knee injuries in the past may have weak joint and muscles, which increase the risk of suprapatellar joint effusion. Meniscus and ligament injuries can cause rapid degenerative changes and cause suprapatellar joint effusion. Improperly healed fractures, repeated or overuse injuries can cause more problems.
Work – Certain occupations require overuse of knees with bending, kneeling and bearing more weight on the knees. This can increase the risk of bursitis, weakening of knee joint and suprapatellar joint effusion in some people.
Symptoms of Suprapatellar Joint Effusion
Suprapatellar joint effusion is a symptom of an underlying condition. However, some of the complaints associated with it can be considered as symptoms of suprapatellar joint effusion. It is important to know these to be able to seek timely medical advice.
Some of the symptoms of suprapatellar joint effusion include:
Stiffness – Stiffness is more prominently noted during knee movement. Suprapatellar joint effusion makes it difficult to bend or straighten the knee joint completely. It brings a feeling as if the knee is stiff and unable to move.
Swelling – Normal fluid in the knee joint is not visible, but when there is water on the knee, it just swells up. Visible puffiness or swelling of the knee joint is one of the most characteristic symptoms of suprapatellar joint effusion.
Pain – Pain is usually severe when suprapatellar joint effusion is sudden or due to injuries. It may be mild or dull aching in chronic conditions, but some acute exacerbations can cause severe pain too. The degree of pain may depend on the cause and severity of the condition.
Restricted Movement – In suprapatellar joint effusion, it is difficult to move the knee joint and standing or walking may not be possible in severe cases. When tried to bear weight, the knee may give out, as if there is no strength.
In case of some acute injuries, there can be extreme stiffness and slightest movement can bring on pain. Injuries may also be present with a history of trauma and bruising around the injured area. In degenerative changes, clicking or ticking sound may be heard on knee movement with some pain. When suprapatellar joint effusion is caused due to inflammation or infection, fever, warmth of knee joint and redness may be noted. However, mild rise of temperature can be seen in mild inflammation, but high fever with suprapatellar joint effusion may be due to infectious causes.
Diagnosis of Suprapatellar Joint Effusion
A careful history and clinical examination often gives an idea of suprapatellar joint effusion. However, certain investigations may be ordered for diagnosis of suprapatellar joint effusion. It helps to find the exact nature of injury and to rule out complications in cases of injuries. While in other cases, investigations help to detect presence of inflammation, infection and the severity and extent of suprapatellar joint effusion.
Diagnosis of suprapatellar joint effusion is based on the following tests.
- Blood tests to detect inflammation, infections, autoimmune conditions and risk of gout, or other joint conditions.
- X-rays to detect bony deformities, to assess fractures, joint degenerative changes
- MRI and CT scans may be ordered to determine injuries, joint problems or other medical conditions causing suprapatellar joint effusion.
Joint fluid aspiration may be done in severe cases to confirm the diagnosis of suprapatellar joint effusion and detect the underlying cause. In this, a small amount of fluid in the knee is aspirated with a long needle by locally numbing the area. The aspirated fluid is sent for laboratory analysis, to detect the presence of inflammatory cells, bacteria, pus cells, blood cells, crystals, glucose or protein. Based on the results, the exact cause of knee swelling can be confirmed and treatment can be planned accordingly.
Treatment of Suprapatellar Joint Effusion
Treatment of suprapatellar joint effusion should begin when first noted and evaluated by the physician. R.I.C.E (Rest, Ice, Compression and Elevation) formula is generally applied as first response, with medical advice.
Medical Management – Some of the medications used to treat suprapatellar joint effusion include anti-inflammatory medicines for pain and anti-biotics if infection is suspected. Steroids medications may be given orally in some cases. Knee braces may be advised for some period to support the knee joint and prevent further damage. Calcium and vitamin D supplements may be considered for long term management, if necessary.
Joint Aspiration – Joint aspiration provides some relief, as it removes some accumulated fluid, hence it relieves pain and stiffness of the joint. Steroid injections may be given after fluid aspiration, in some, to offer immediate relief. The tests results are awaited, based on which further treatment is given. Depending on the results, appropriate medicines are given and further treatment plan is decided.
Surgical Treatment – Some cases of suprapatellar joint effusion or correction of injuries may need arthroscopy as a part of treatment. In this, a scope with a camera is inserted into the joint to view the area and repair the damage. In advanced cases, conditions that do not improve, severe degenerative changes and in repeated knee swelling, knee replacement surgery may be advised as a treatment of suprapatellar joint effusion.
Physical therapy is an important part of treatment of suprapatellar joint effusion, however, it must be done, as advised by the treating physician. Physical therapy includes the use of treatment modalities to provide relief from knee pain, swelling and aims at improving joint function and mobility. It also includes strength building and flexibility exercises, to improve knee joint. When performed regularly, as advised, these can help build the knee muscles and prevent recurrent swelling and pain.
As the knee recovers with appropriate treatment and exercises, self-care measures to manage the condition are equally important.
Have a healthy diet with essential nutrients and drink plenty of water to stay hydrated. A diet rich in protein, calcium and whole grains can help. Maintain a healthy weight, as weight increases the trouble. Even slightest weight reduction can have great effects on knee pain and swelling.
Therapeutic exercises of the knee help keep the knee strong and prevent injuries. These are best done as advised by the physical therapist or treating doctor. Regular exercises can help keep the body fit and supple. Low impact exercises like walking, swimming or aqua aerobics can help build strong knees without putting pressure on them. Wear sport shoes that protect the feet and knees from high impact.
Those involved in sports must do a proper warm up before play and cool down or stretch after sports activities to avoid injuries. It is important to maintain a balance of activities and take rest, when needed, without overusing the knee joint. Apply ice to the knee joint after strenuous activities or sports, it can keep suprapatellar joint effusion in control. Elevate your legs and knees, if there is pain or mild swelling. Seek medical advice in case of injury or if you note symptoms of suprapatellar joint effusion, for timely treatment.