Orthopedics
Popliteal cyst
The structure of the knee joint: anatomy and function
The knee joint is the largest and one of the most complex joints in the human body. It connects the femur, tibia, and kneecap and enables a wide range of movements essential for everyday life and sporting activities. At the same time, the knee is subject to high levels of stress and is therefore prone to injury and wear and tear. Here's an overview of the anatomy and function of this fascinating joint.
Anatomical structures of the knee joint
1. Bone
The knee joint is formed by three main bones:
- Femur (thigh bone): The lower part of the femur forms the two bony joint rollers (femoral condyles), which pass into the tibia.
- Tibia (shinbone): The upper end of the tibia forms the articular surface on which the femoral condyles rest.
- Patella (kneecap): The patella protects the knee joint and serves as a lever for the extensor muscles.
2. Articular cartilage
The bony articular surfaces of the femur and tibia, as well as the back of the patella, are covered with smooth cartilage. This cartilage ensures frictionless movement and dampens the forces acting on the knee.
3. Menisci
Between the femur and the tibia lie two crescent-shaped cartilage structures, the menisci:
- Medial meniscus: Located on the inside of the knee.
- Lateral meniscus: Located on the outside of the knee.
The menisci act as shock absorbers and stabilize the joint by distributing the force evenly.
4. Bands
The knee is stabilized by several strong ligaments:
- Anterior cruciate ligament (ACL): Prevents the shinbone from sliding forward.
- Posterior cruciate ligament (PCL): Prevents the shinbone from slipping backward.
- Medial collateral ligament: Stabilizes the knee on the inside.
- Lateral collateral ligament: Stabilizes the knee on the outside.
5. Tendons
Tendons connect muscles to bones and play a key role in movement:
- Quadriceps tendon: Connected to the patella and controls extension of the knee.
- Patellar tendon: Connects the patella to the tibia and is an essential part of the extensor apparatus.
6. Joint capsule and bursa
The joint capsule surrounds the knee joint and contains synovial fluid, which acts as a lubricant. Bursae also protect the joint from friction.
Function of the knee joint
The knee joint enables movements such as:
- Flexion:When sitting or squatting.
- Extension: When standing or walking.
- Rotation: Slight twisting movements that occur especially when the knee is bent.
These movements are coordinated and controlled by the muscles, tendons and ligaments.
Special features of the knee joint
1. Stability and mobility
The knee must be stable enough to support the body weight, yet flexible enough to allow various activities such as running, jumping, and turning.
2. Resilience
The knee is one of the most stressed parts of the body. Running or jumping can expose it to forces many times your body weight.
3. Susceptibility to injuries
Due to its complex structure and high load, the knee joint is prone to:
- Cruciate ligament injuries
- Meniscus damage
- Osteoarthritis (cartilage wear)
Summary
The knee joint is a highly complex system of bones, cartilage, ligaments, tendons, and muscles that combines stability and mobility. It plays a central role in locomotion and is essential for numerous movements in everyday life and sports. Understanding its anatomy and function is crucial for preventing injuries and finding the right treatment for complaints.
If you have any questions or complaints about your knee joint, we are happy to assist you in our practice with modern diagnostics and individually tailored therapies.