What structures are damaged if you need a total knee replacement?

If symptoms of pain, immobility, stiffness and swelling have you considering a total knee replacement you’re not alone. The Agency for Healthcare Research and Quality reported more than 600,000 knee replacements per year in the Unites States. The procedure allows patients to have less pain and better knee function. Trauma and osteoarthritis cause damage to the joint, but what structures are actually damaged that cause these symptoms?

Typically patients who are candidates for a total knee replacement have diseased articular cartilage and damaged meniscus. The cartilage and meniscus both function to provide a smooth surface for which the knee to move and act as a shock absorber with impact. Because the cartilage and most of the meniscus do not have a blood supply, they can not heal on their own causing symptoms to increase in severity over time. 

Articular Cartilage

The articular cartilage of the knee is a rubbery tissue that cushions the end of the thigh bone (femur), the top of the shin bone (tibia), and behind the patella (knee cap). It provides a smooth surface in which the knee can glide.  Damaged cartilage is caused from traumatic injuries in sport or work, or gradually worn through osteoarthritis. Damage to the cartilage also causes the growth of bone spurs where the parts of the knee joint meet, causing increased friction and pain. 

Meniscus

The meniscus is made of c-shaped discs of cartilage that sit between the thigh bone and the shin bone. They prevent the ends of each joint from rubbing together as well as providing some shock absorption with impact movements (jumping and hard landings). Meniscus tears happen with excessive twisting of the knee or hyperextension. Depending on where the meniscus tear is, it can be repaired through arthroscopic surgery, but if there is progressive degeneration and weakening of the meniscus it will no longer be able to function properly as intended. 

Resurfacing the Joint

In the total knee replacement procedure the damaged articular cartilage and the meniscus are removed. The shin bone and thigh bone are resurfaced with the implants that make up the knee replacement providing a new smooth and better cushioned surface. Depending on the amount of damage to the knee cap, it may also be resurfaced with new material. 

The anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) are commonly removed. In most cases, the ligaments are weak or completely torn prior to surgery. The components of the total knee replacement are designed to provide the same amount of stability in the knee joint. 

If you are suffering from knee pain, you should seek help from an experienced knee surgeon. Contact the Heekin Clinic today to schedule an appointment.

 

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