It can be argued that few joints in the human body contribute as much to day to day life as the knee does. The knee is needed to walk, run, stand up, and even relax by putting one’s feet up at the end of the day. As a consequence, the knee takes a lot of abuse and can wear out prematurely as a result of the constant loads that one puts it under day in and day out.
The knee is made up of a collection of bones, ligaments, and cartilage that work together to act as shock absorbers to transfer load throughout the leg. The femur comes down along the thigh and enters the patella (also known as the knee cap), which connects to the tibia below the knee. Ligaments such as the ACL (anterior cruciate ligament) and PCL (posterior cruciate ligament) …show more content…
The knee can withstand up to 1,500 N of force at a time, so the material used in the replacement must be sturdy, but still be able to yield under force in the same way that the menisci do. The average Young’s modulus for the menisci can be approximated at around 80 kPa. To make a successful knee replacement, it must contain three parts. First, the femoral component must be anatomically correct. This is the part that anchors into the femur. Due to the differences between the two legs, the correct side must be used. Second, the trochlear groove must be correctly matched to the particular patient. The trochlear groove is the area where the patella rests on top of the femur. The depth, length, and angle of funneling must be approximately correct for each patient to allow for comfort. Last, the replacement needs to account for the patient’s PCL situation. If the entire PCL had to be removed, the prosthesis must include a PCL substitute. Otherwise, the replacement can either be implanted around or help support any existing PCL. More advanced replacements include the ability to allow minimal rotation as opposed to forward-back movement. When turning or leaning, the knee joint tends to shear as opposed to fold over itself. A prosthesis that includes this feature can help bridge the gap between the life with a biological knee and that with a
The knee is made up of a collection of bones, ligaments, and cartilage that work together to act as shock absorbers to transfer load throughout the leg. The femur comes down along the thigh and enters the patella (also known as the knee cap), which connects to the tibia below the knee. Ligaments such as the ACL (anterior cruciate ligament) and PCL (posterior cruciate ligament) …show more content…
The knee can withstand up to 1,500 N of force at a time, so the material used in the replacement must be sturdy, but still be able to yield under force in the same way that the menisci do. The average Young’s modulus for the menisci can be approximated at around 80 kPa. To make a successful knee replacement, it must contain three parts. First, the femoral component must be anatomically correct. This is the part that anchors into the femur. Due to the differences between the two legs, the correct side must be used. Second, the trochlear groove must be correctly matched to the particular patient. The trochlear groove is the area where the patella rests on top of the femur. The depth, length, and angle of funneling must be approximately correct for each patient to allow for comfort. Last, the replacement needs to account for the patient’s PCL situation. If the entire PCL had to be removed, the prosthesis must include a PCL substitute. Otherwise, the replacement can either be implanted around or help support any existing PCL. More advanced replacements include the ability to allow minimal rotation as opposed to forward-back movement. When turning or leaning, the knee joint tends to shear as opposed to fold over itself. A prosthesis that includes this feature can help bridge the gap between the life with a biological knee and that with a