Total Knee Replacement, also known as Total Joint Arthroplasty (“Arthro” meaning joint, “Plasty” meaning refashioning) has become one of the most common elective surgeries along with Total Hip Replacement. Anyone reading this article will likely know of a relative or friend who has had this surgery. As more of us live longer and the tissues “go grey” or wear out this trend is only going to continue.
How do you know if your joint needs to be replaced?
The most typical reason to consider this type of surgery is when the cartilage of the joint has worn away (Osteoarthritis) and is producing significant pain and disability with respect to walking, stair climbing, sleeping.
What is involved in the surgery
The goal of surgery is to reduce pain and improve function by removing what is left of the joint’s surfaces and resurfacing the ends of the bones, in this case the femur and tibia with artificial components made of metal and plastic. These new components, called a “prosthesis” are precisely attached to the ends of the bones to replace the lost cartilage and replicate the original anatomy. This is major surgery by any stretch and for those interested you can see how a surgeon performs the procedure on YouTube.
One thing to remember is that you are not getting new muscles or ligaments from this surgery and therefore an important part of the process is to work diligently preoperatively and postoperatively to maintain flexibility and strength of the thigh and hip muscles. Obviously, pain can often be an issue pre-op which is the reason most patients pursue the surgery and this may limit your ability to exercise however during the post op phase, with appropriate pain medication, patients are guided through a program of progressive flexibility and strengthening exercises for the knee and hip to maximize function.
Job one typically focuses on pain/swelling control and restoration of knee bending from the fully straight position to around 110 degrees and retraining balance and coordination for safe ambulation. Once adequate range of motion has been achieved exercise therapy focuses on specifically training the hip and thigh muscles in more functional positions to enhance balance and weight bearing tolerance. These exercises do not harm the prosthesis. The rate of progress is variable for different patients but usually the overall recovery takes about six-eight months in my experience.
Improving your surgical outcome
In addition to diligently following a quality rehab program there are also some lifestyle issues that you can address which can positively influence the outcome.
- Weight control means less physical loading of the joint over time meaning a better chance of the components lasting longer. Like any other mechanical system of moving parts loading applies compressive/frictional forces which will produce wearing of the surfaces. This is normal and the prosthesis is engineered to withstand these forces and perform during normal functional activities.
- The other important lifestyle issue to address is reducing/ avoiding tobacco consumption, for the reason that this negatively impacts the quality of blood flow to the tissues in this case bone.
How long will your new knee last
The prosthesis is attached to bone therefore the stability of the bond between the metal/plastic and the underlying bone is important. Trying to find a consistent figure for the longevity of a new joint is hard to pin down and is probably influenced by many factors but generally what I’m hearing from patients who ask this question of their surgeons is usually between 10-15 years.