Knee Anatomy The knee is one of the most complex joints in the human body; in addition to bending and straightening, it allows for other complex movements such as rotation. The knee joint consists of three bones the femur (thigh bone), tibia (lower leg bone) and patella (kneecap). The lower end of the femur, the upper end of the tibia and the inner surface of the patella are covered by articular cartilage, which is a tough, very smooth substance. It ensures that the knee joint moves painlessly and smoothly. Between the ends of the femur and tibia are two other pieces of cartilage called menisci. It acts as a liner. The knee joint is encased in a joint capsule lined with a synovial membrane, which produces synovial fluid (a sticky substance which provides frictionless gliding). The synovial fluid and meniscus work together to absorb oscillations. Together, they absorb the forces acting on the joint as it moves. Tough ligaments connect the femur, tibia and patella and cover the joint to stabilize it. Movement of the knee is triggered and controlled by the strong muscles of the thigh and calf. A healthy knee joint allows the lower limb to move freely within its range of motion and absorbs shock from walking and running activities. Conditions Requiring Knee Replacement There are many conditions that make knee replacement surgery necessary. Probably the most common condition is osteoarthritis, which usually refers to arthritis that manifests itself in wear and tear and breakdown. Osteoarthritis can develop from wear and tear of the knee joint without the patient having a prior knee injury. The main problem with osteoarthritis is that the cartilage in the joint wears away, which causes the bones to rub against each other during movement, resulting in stiffness swelling and pain. Knee trauma, fractures, torn menisci and ligaments lead to abnormal knee function. It can trigger degeneration many years later. Mechanical abnormalities trigger excessive wear and tear, like a poorly aligned tire that wears out quickly. Rheumatoid arthritis and congenital disorders can also trigger bone or joint breakdown, and gradually these changes lead to the destruction of articular cartilage. These changes cause excessive wear and tear on bone and bone, producing pain. Treatment Options There are many ways to get relief from your knee pain, which include lifestyle changes or taking pain medication, another option is to have your knee surgically replaced. Knee replacement is usually recommended when the pain becomes persistent, interferes with your daily life, and you and your specialist agree that it is the best treatment option. About Knee Replacement Surgery The purpose of knee replacement surgery is to: Relieve pain Correct any deformities such as O-legs, K-legs Restore the lost function of the knee Improve your quality of life Knee replacement surgery involves the replacement of the surfaces of the femur, the end of the tibia, and the inside of the patella with artificial materials called prostheses. Knee prostheses are designed to mimic human anatomy to the greatest extent possible. Based on the damage to your knee, Prof. Choi may decide to give you a total knee surface replacement or a partial knee replacement. There are many different knee prosthesis designs, and the specialist will choose the one that is most suitable for you. Knee Replacement Prosthesis Each knee prosthesis consists of several parts: 1. Femoral Prosthesis: Surface replacement of the end of the femur. The femoral prosthesis consists of a metal alloy. 2, Patellar prosthesis: replaces the inner surface of the patella that rubs against the femur. The patellar prosthesis consists of plastic with a metal alloy back plate. 3, Tibial prosthesis: can be a single or two piece design. The single design consists of plastic and the two-piece design consists of a metal buttress attached to the bone and a plastic spacer. The plastic spacer provides a smooth surface over which the femur moves. The plastic spacer is usually attached to the tibial tray. Knee replacement surgery is a very well established procedure that is safe and effective. As with all surgeries, your surgeon will ask you to make certain preparations to ensure the success of your surgery. If you have any questions or concerns please ask Prof. Chua. The next step is for you to understand what you will be asked to do before and during your hospitalization and when you go home to recover. Before you go to the hospital before your surgery it will make your recovery easier and safer if you are prepared for the following. Take responsibility for the success of your surgery. As a team, you, your orthopedic specialist, your physical therapist and your family must adopt a positive attitude toward your surgery. Working together will give you a clear understanding of what will be accomplished and the outcome of your surgery. Try to stay proactive. Staying active while waiting for your surgery is an important key to the success of your surgery. Studies have shown that the stronger and more flexible you are before surgery, the faster you will recover and the more flexible you will be after surgery. Light exercise, such as walking, proper range of motion, and swimming, can help you stay strong and flexible. Ask your doctor for advice before you start any exercise. Stop smoking. If you haven’t already done so, stopping smoking at least four weeks before your surgery will help reduce your risk of complications during and after surgery. Stop taking certain medications that interfere with your surgery. If you have been taking medications such as aspirin or Sulpiride for a long time for other medical conditions, you should stop taking them for the time being, as the former may increase the tendency to bleed at the site of the surgery during or after the surgery, and the latter may cause hypokalemia, among other things, which may increase the risk of intraoperative and postoperative complications. Ensure that all infections are cleared before surgery. This includes inflammatory conditions such as gum abscesses, bladder infections, lower extremity ulcers or tinea pedis, colds and flu. This is because infections can spread through your body during surgery and infect your newly replaced joint. It is therefore important for you to inform Prof. Choi immediately that you have been suspected or diagnosed with some kind of infection, which will require rescheduling your surgery. You can imagine how you will cope with the surgery, for example, you may need someone to help you to go home, to do your shopping and so on. Be sure to discuss this with your specialist. During your stay in the hospital you should check in well before your surgery to settle yourself down. The surgeon and anesthesiologist will come and check you over; as well as undergoing a heart, chest, etc. This is a good opportunity for you to ask questions before the surgery. On the day of surgery you will usually be asked not to drink or eat anything. The area around your knee may be trimmed of body hair to minimize the risk of infection. About an hour before your surgery you will be given tablets or intramuscular injections to relax you, which are pre-operative medications. You will then be taken to the operating room for anesthesia and surgery. Surgery usually takes one to two hours to complete. After surgery, you will be moved to a recovery room for monitoring. There will be one or two IV drips in your arm to feed fluids into your body. Upon awakening from the procedure, your lower extremities may be swollen with superficial scars and your muscles may be stiff and sore. Your new joints will not cause any discomfort, but you may experience pain from the surgery itself. Pain medication will be given regularly during your recovery. You will be taken to the ward when you are fully awake and your breathing, blood pressure and pulse are stable. Please follow the instructions of the anesthesiologist and the surgeon who operated on you as to when you can eat or drink. The wound on the side of your knee will gradually disappear, changing to a thin white-colored scar after six months. The fluids will gradually be stopped in the following days. A specialist will check in on you the day after surgery to help you begin rehabilitation so that you can start walking again. Three days after the operation the drains from the surgical site will be removed and you will be able to get down to the floor and practice walking with the aid of a walker. Initially you may feel unsteady and some pain. You will need a walker at first, then crutches. This process takes four to six weeks, and recovery time will of course ultimately depend on your doctor’s instructions. Once your doctor is satisfied with your condition and mobility, you can be discharged. A typical knee replacement hospital stay is 10-14 days. Home Recovery Once you return home, you will need to continue your regular medications, continue to exercise as directed by your Physical Therapist and doctor, and continue to stay active as the fastest way to a full recovery. Recovering in anticipation of gaining full function of your lower limbs takes time. Within a few months after surgery, and in consultation with Prof. Chua, you can resume your normal activities, which may include driving, tending to your garden, light exercise, and continued improvement in your quality of life for the first twelve months. When you are fully recovered, it will not be obvious to many people that you have had an artificial knee joint fitted. SPECIAL NOTES Great effort is devoted to minimizing any dangers and complications, but as with all other surgeries, dangers and complications are possible. Below is a list of common signs and symptoms that may indicate the presence of a complication with your new joint.