Total Knee Replacement
Repeated injuries, arthritis, wear and tear or trauma to the joints can lead to debilitating and irreparable damage. This is particularly true of the knee – the joint that handles the brunt of our daily activities. When the knee joint has been damaged to the point where regular daily activities are no longer possible or enjoyable, the idea of a knee replacement becomes more palatable to most patients.
Knee replacement surgery has been around for many decades and improvements in surgical technique and hardware have made it routine; to where the safety profile and effectiveness is higher than ever before. In the US, over 750,000 knee replacements are performed each year, both safely and with excellent postoperative results.
What Leads to Knee Replacement Surgery?
The culmination of injury, age and excess weight are often to blame for significant degradation of the knee joint. However, of these, arthritis is the single most common reason for having a knee replacement. Arthritis comes in three main forms – posttraumatic arthritis, rheumatoid arthritis and osteoarthritis.
Post traumatic arthritis occurs in the aftermath of a serious knee injury. Fractures in the bone or tears in the ligaments can cause long-term limited function and chronic pain. Some patients, even if their knee heals very well after a trauma, will have mild to moderate arthritis. Others will experience more severe cases.
Rheumatoid arthritis is a progressive, autoimmune disorder that involves inflammation of the synovial membrane in the knee. An autoimmune disorder is one where the body’s natural defense – the immune system – turns on healthy tissue (in this case the joints). If the inflammation around the joint is left untreated or under treated, damage to the cartilage can lead to significant pain, stiffness and disability.
Osteoarthritis is the most common reason for knee replacement. Osteoarthritis is essentially wear and tear of the joints. While osteoarthritis was once found predominantly in middle to older age adults, today’s patient population suffering from osteoarthritis is much younger, due, in part, to the obesity epidemic. As a point of reference, for every extra pound of body weight, the knee is saddled with an extra 4 pounds of pressure. Further, the chemical imbalance arising from adipose or fat tissue has been shown to further degrade the joints, making osteoarthritis even more prevalent.
How a Knee Replacement Works
A knee replacement is when the surface of the damaged bone is replaced with an implant. The entire bone is not completely removed. Most modern knee replacements are actually more of a “resurfacing” of the joints. The surgery is performed under general or spinal anesthesia in a hospital or ambulatory surgery setting. A small incision is made over the kneecap and the knee joint is exposed by moving the kneecap to the side. The damaged cartilage overlying the femur and tibia are removed as is small amounts of underlying bone. Typically only 9 mm of bone is removed from the femur and tibia.
Once the surface of the knee is prepared, metal implants are attached to the bone to re-create the joint’s natural anatomy. These prostheses can be attached using specialized cement or press fit devices. The kneecap may also be resurfaced, but this is not performed in every knee replacement and remains at the surgeon’s discretion.
Just as with natural cartilage, there must be a smooth surface on which the metal components can glide without touching each other. This is replicated using special plastic spacers that have the same basic function as cartilage.
When Is the Right Time to Consider Knee Replacement Surgery?
Knee replacement surgery is not an emergency procedure and because the progression of the disease can be rather slow, many patients modify their lifestyle to live with the pain and inflammation. When to have knee replacement surgery is a very personal decision that must be made with family, trusted friends and of course the medical team around you. However, the basic criteria for a patient to consider knee replacement surgery may include:
- Severe pain or stiffness in the knee that interferes with daily activities
- Knee inflammation that can no longer be well-managed with rest, ice and anti-inflammatory medication
- Deformities in the knee
- Failure of other less invasive options including Cortisone injections and physical therapy.
While age was once a consideration for knee replacement surgery, virtually anyone can have the procedure today. However, we pay special attention to those with any conditions or diseases that may affect their safety during the procedure. For example, uncontrolled diabetes and smoking may increase the risk of preoperative and postoperative complications significantly.
Results and Outcomes of Knee Replacement Surgery
Total knee replacement is a very gratifying procedure because patients experience relief from chronic pain almost immediately after surgery and simply have some surgical pain from the incision. By the time they have fully recovered from surgery, patients are often able to perform activities they may not have for years or even decades.
However, we must treat this new knee with care. The plastic spacers inside the joint will wear down much like cartilage would. Therefore strenuous, high impact activities and anything that puts undue strain on the implant can cause it to fail prematurely. However, most implants can be expected to last between 15 and 20 years – some even longer. While we do not suggest high impact activities, many activities such as swimming, walking, golfing, biking and other low impact sports are just fine for most.
Complications of Knee Replacement Surgery
As with any major surgical procedure, complications do arise after total knee replacement surgery. With improvements in technique and by employing an experienced orthopedic surgeon, these complications can be mitigated. Infection in the knee occurs in less than 1% of all patients. Though medical complications can occur with any surgery, our specialists will help you decrease those risks before surgery. This includes weight loss to help you achieve a healthy weight before surgery, smoking cessation, and improved blood sugar control.
Other complications may include blood clots, which is also rare. With the appropriate medications, therapy, and leg exercises, the risk of blood clots is less than 0.5 %. An allergic reaction to the implant material or design is quite rare. However, if you have a known metal allergy, our specialist can use a special implant with little to no Nickel to help decrease an allergic response. Continued pain, infection, and injury to surrounding nerves or blood vessels are also part of the risk of any surgery. However, these risks can be mitigated by employing an experienced orthopedic surgeon.