The knee joint is a hinged joint, with the primary movements of bending backward, known as flexion, as well as bending forward, which is known as extension. Also, there is a small amount of rotation of the joint as it moves through the full range of flexion and extension. Learn more below.
Knee Pain Anatomy
Understand your knee pain anatomy and get treatment options and relief for your knee condition
Knee Pain Anatomy
Primary bones involved in knee joint pain
The femur or thighbone is the largest bone in your body and plays a critical role in the knee joint. The femur bone forms the top of the joint and is commonly involved in knee pain related to osteoarthritis.
The tibia or shinbone is the second most important bone of the knee joint and makes up the lower part of the joint.
Finally, the patella or kneecap helps protect the knee joint from injury and may also be involved in some forms of knee arthritis.
Knee Pain Meniscus Anatomy
The "cushion" of the knee
The knee menisci are a pair of protective connective tissue structures within the knee joint. Referred to individually as a meniscus, they act as shock absorbers or cushions between the femur and the tibia bones described above. This part of the knee is a very common area of traumatic injury and degeneration that leads to arthritis. Despite medical studies showing that many patients with meniscus damage do not have pain, patients are routinely referred for meniscus surgery only to receive no benefit. The meniscus is only one of many structures that may be involved in your knee pain, and an MRI should not be the only factor in determining your treatment options.
Knee Capsule Pain Anatomy
The structural balloon around your knee
The joint itself is encased in a thin layer of connective tissue that wraps around the joint, which is the joint capsule. This capsule, whether in the knee or other joints, contains synovial fluid. In the healthy knee, this joint fluid lubricates the joint and contains nutrients that help maintain the joint. Normal synovial fluid appears clear or straw-colored with the consistency of egg whites. When the knee joint becomes inflamed, such as with arthritis, the amount of fluid may increase, forcing the joint capsule to expand. This expansion of the joint fluid and capsule is referred to as swelling or joint effusion.
Knee Pain Ligament Anatomy
The link between knee bones
Ligaments are a tough connecting tissue that links bones to other bones and serve a vital role in joint structure. Multiple ligaments exist within the knee, and four major ligament structures contribute to overall knee stability.
- Anterior cruciate ligament (ACL) – pictured
- prevents excessive forward movement of the shin bone (tibia)
- Posterior cruciate ligament (PCL)
- prevents excessive backward movement of the shin bone (tibia)
- Medial collateral ligament (MCL) – pictured
- helps stabilize the inside of the knee joint
- Lateral collateral ligament (LCL) – pictured
- helps support the outside of the knee joint
- Iliotibial Band (IT Band) – pictured below
- runs down the outside of the thigh and attaches to the shinbone
Knee Pain Tendon Anatomy
Connecting muscle to bone
Tendons also contribute to the stability and structure of the knee. Tendons are the tissue connectors of muscles to bones. There are several critical tendons that the knee depends on to function properly, which include:
- Quadriceps tendon (pictured)
- Patellar tendon (pictured)
- Hamstring tendons
- Pes Anserine (pictured)