What is the normal anatomy of the knee joint?
The knee is one of the largest joints in the body, formed by the lower end of the femur, upper end of the tibia and the patella or knee cap. Several ligaments and muscles attach to the bones of the knee joint to maintain normal motion of the joint. Special cartilaginous tissues known as menisci are placed between the two articular ends of the joint. These act as a cushion between the articular surfaces and absorb the shock during movement.
To learn more about Knee Anatomy, click here.
How does knee pain occur?
Knee pain is a common condition affecting individuals from different age groups. It not only affects movement but also impacts the quality of life of the individual. An injury or disease of the knee joint or any structure surrounding the knee can result in knee pain. A precise diagnosis of the underlying cause is important to develop an appropriate treatment plan.
What are the causes of knee pain?
Some of the common causes for knee pain include:
- Arthritis: a condition associated with wear and inflammation of the joint
- Knee ligament or tendon injuries (4 ligaments & 2 tendons). Anterior Cruciate Ligament most common injury
- Torn meniscus
- Subluxing or Dislocating kneecap (acute or chronic)
- Patellar tendonitis: inflammation of the patellar tendon which connects the kneecap to the shin bone (Quadriceps tendon can also have this problem).
- Chondromalacia Patellae (CMP): softening or wear of the articular cartilage on the under surface of the kneecap causing knee pain
- Baker's cyst: a fluid-filled swelling in the back of the knee which usually results from another problem such as a meniscus tear or arthritis
- Knee bursitis: inflammation of the bursae, small fluid-filled sacs located around the joints, usually between a tendon and the bone.
- Plica syndrome: results from inflammation of the synovial tissue of the knee causing knee pain and swelling. (there are 3 different plicas in the knee)
- Osgood-Schlatter disease: caused by irritation of the growth plate where the patella tendon attaches onto the tibia at the front of the knee joint and is more common in adolescents
- Osteochondritis Dissecans (OCD): characterized by detachment of an articular cartilage fragment and an underlying attached thin layer of the bone from the end of a bone due to inadequate blood supply; these fragments may either stay in place or slide around the joint causing pain and joint instability
- Gout: characterized by sudden, severe attacks of joint pain, with swelling and redness around the joint, caused by accumulation of uric acid crystals in the joints
- Referred pain from hip or back: Sometimes spinal or hip problems present with knee pain. It is unlikely that foot and ankle problems present with knee pain
- Other causes: there are several additional causes of knee pain that are extremely rare
What diagnostic procedures may be required to evaluate knee pain?
- History and examination: All knee conditions should be evaluated by a detailed medical history and physical examination of the knee which is crucial for the diagnosis.
- Diagnostic imaging studies such as X-rays, MRI scans, CT scans, ultrasound and bone scans are sometimes needed. Sometimes MRI scans can be misleading as they can show abnormalities which are NOT producing symptoms. Hence 1 above is important.
- Blood tests may be performed to identify any infection, gout or pseudo gout.
- Sometimes arthrocentesis may also be performed, wherein the fluid from the knee joint is removed and sent for laboratory analysis.
What are the treatment options for knee pain?
Treatment options depend upon the underlying cause responsible for knee pain. Some of the common treatment options for knee pain include rest, ice and heat application, non-steroidal anti-inflammatory medications, stretching, physical therapy and cortisone injections.
Sometimes a knee arthroscopy may be performed. Knee arthroscopy is a surgical procedure in which the internal structures of the joint are examined to diagnose as well as treat the underlying problem.
Acute sports injuries to the knee are usually easy to work out with History, Examination and MRI to allow an optimum treatment and recovery plan, with a speedy safe return to sport.
A knee that is clearly suffering advanced arthritis is at certain ages best managed by proceeding straight to a knee replacement, BUT this is a serious "large" operation to be approached only with a full understanding of the path ahead and a very healthy dose of determination to do the difficult and painful rebab.
If you have trouble or inability to walk, deformity around the joint, inability to bend the knee, knee pain persisting beyond a few days and more at night, or pain associated with swelling, warmth, or redness, you should consult your doctor for immediate medical intervention.