What Type of Joint Is the Femur?

Deep hollows and smooth bone in the hips and knees connect the femur with ligaments, tendons and muscles. Gliding across protective cushioning, these joints allow easy movement of muscles attached to physical limbs. Without joints, motion would be stilted and unbalanced. Bending, twisting, turning, leaping and even standing require joint movements. The largest joints in the body are in the hips. Two joints that hold the femur are the hip and knee.

The Femur

• The femur is the longest and strongest bone in the human body.

  A strong bone that assists movements of the hip and knee, the femur increases the body's resilience to dance, walk, run, bend and twist the lower half of the body. The femur head closest to the pelvis in a ball-and-socket joint and the head at the knee is a hinge joint. The femur is not a joint but a bone that supports the movements of ball-and-socket and hinge joint. The femur connects the hip with a synovial or open joint and at the knee with a cartilaginous joint.

Hip Joint

• The knee joint combines the femur and tibia.

  Inside each bone in the hip is a blood and nerve supply that nourishes the structures. Each bone is strong and flexible and supports hundreds of pounds of body weight and stress from the impact of rapid, jarring movements. The bowl shape of the hip joins several bones, the top and bottoms half of the pelvis as well as spinal attachments at the back. The synovial, or free movement joint joins the pelvis and the spine to the femur. This joint can move backward, forward, glide side-to-side, roll and twist within the ball-and-socket structure. The incredible flexibility in the hip joint permits agility, durability and support all at the same time. The head of the femur rotates in a little hollow in the hip, cushioned by cartilage, surrounded by ligaments, tendons, muscle tissue and skin.

Knee Joint

• The acetabulum in the hip allows fluid movement of the femur.

  The femur, tibia and patella that make up the knee joint stabilize the hips, ankles and feet. The hip and knee hinge-joint works together to create secure yet restricted movement. The knee does not have the same flexibility as the hip because it is a cartilaginous joint, with limited movement from the bones and cartilage attachments. The knee can bend and extend. This joint allows a person to bend and balance in this flexed position and to stand erect, balancing while in the standing position. Without the knee joint, the hips and smaller ankle joint would need to carry the weight, pressure and torque of the whole body as well as the pressure of gravity each time a person jumps, crouches, runs, walks or combines any of these movements.

Considerations

• The femur and tibia joint allow the knee to extend and flex.

  Although these joints and bony structures are strong, flexible and provided with a constant supply of new cells, blood and nerve tissue, it is susceptable to impact damage. Weak muscle tissue, excess body weight, misalignment of the joints and poor nutrition can cause the tissues that support the joints to weaken. Joints that stiffen, slip or loosen from their support system can damage balance, flexibility and overall joint health, notes the University of Delaware. To avoid damage to the joints, stretch, exercise, weight train, eat well and hydrate.