Knee replacement surgery (knee arthroplasty)
Degenerative conditions (wear and tear) of the knee is common. Osteoarthritis is the most common cause of knee arthritis and usually affects older individuals. Other forms of arthritis includes post traumatic arthritis and inflammatory arthritis (e.g. rheumatoid arthritis and gout). Knee replacement surgery (knee arthroplasty) is an a highly successful treatment for debilitating arthritis where other treatments such as anti-inflammatory and pain medication, lifestyle modification, physiotherapy have failed to achieve relief from pain and maintenance of your activities of daily living.
Importance of alignment and ligament balancing in knee arthroplasty
Up to 15 percent of patients will encounter dissatisfaction with their knee replacement. This can often be attributed to mal-alignment of the knee and failure of the surgeon to adequately balance the knee so that the gap (joint space where the plastic liner is inserted) between the femur and tibia is equal when the knee is extended and flexed.
A gap that is smaller (tighter) in extension will lead to the inability fully straighten the knee. On the other hand, if the gap is smaller when the knee is flexed, this leads to an inability to fully flex (bend) the knee. Both of these situations is likened to the knee joint being a cam rather than a hinge and will lead to a reduced range of motion. If the knee can't flex to 90 degrees or more, or, the knee can't get within 15 degrees of being straight, this will impact on the function of the knee. This includes difficulty with walking, climbing and descending stairs and the difficulty with riding a bicycle.
They key to achieving a well functioning knee replacement is to ensure that the gap between the femoral and tibial component remains uniform throughout the range of motion of the knee. Accurate bone resections allow the implant of the correct size to be placed in the correct alignment. Releasing of tight soft tissue structures around the knee is also very important in achieving a well balanced knee. Gap balancing is an important aspect of performing a total knee replacement. Dr. Pak is an advocate of this technique and utilises this for all of his total knee replacement procedures.
Bleeding and blood loss
Bleeding and blood loss in joint replacement surgery can have a significant impact on the outcome of this type of surgery. Failure to control excessive bleeding during surgery can lead to persistant bleeding after surgery. A haematoma (blood collected within the soft tissues) or a haemarthrosis (blood within the knee joint) can occur. This will lead to a delay in recovery due to stiffness and can lead to a catastrophic complication such as a deep prosthetic joint infection.
Loss of a significant amount of blood may require treatment with a blood transfusion. A blood transfusion is usually from a donor that is another individual (allogenic blood). This has the risk of disease transmission and weaken will the immune system and reduce its ability to stave off infection in such a crucial period. This again increases the risk of infection.
Minising blood loss requires a meticulous approach to stop bleeding during the procedure (haemostasis). Additional measures that are effective include the use of special agents that reduce bleeding. These agents include Tranexamic acid and the use of Adrenaline in the irrigation fluid during the procedure. These measures are very effective at reducing haematoma, haemarthrosis and persistant wound drainage after surgery. It also is effective at reducing the requirement of allogenic blood transfusion.