Knee replacement surgery — also known as knee arthroplasty (ARTH-row-plas-tee) — can help relieve pain and restore function in severely diseased knee joints. The procedure involves cutting away damaged bone and cartilage from your thighbone, shinbone and kneecap and replacing it with an artificial joint (prosthesis) made of metal alloys, high-grade plastics and polymers.
In determining whether a knee replacement is right for you, an orthopedic surgeon assesses your knee's range of motion, stability and strength. X-rays help determine the extent of damage.
There are four basic steps to a knee replacement procedure.
- Prepare the bone. The damaged cartilage surfaces at the ends of the femur and tibia are removed along with a small amount of underlying bone.
- Position the metal implants. The removed cartilage and bone is replaced with metal components that recreate the surface of the joint. These metal parts may be cemented or "press-fit" into the bone.
- Resurface the patella. The undersurface of the patella (kneecap) is cut and resurfaced with a plastic button. Some surgeons do not resurface the patella, depending upon the case.
- Insert a spacer. A medical-grade plastic spacer is inserted between the metal components to create a smooth gliding surface.
- Knee replacement surgery, like any surgery, carries risks. They include:
- Blood clots in the leg vein or lungs
- Heart attack
- Nerve damage
Reasons for Knee Replacement
Knee replacement is one option to relieve pain and to restore function to an arthritic knee. The most common reason for knee replacement is that other treatments (weight loss, exercise/physical therapy, medicines, and injections) have failed to relieve arthritis-associated knee pain.
The goal of knee replacement is to relieve pain, improve quality of life, and maintain or improve knee function. The procedure is performed on people of all ages, with the exception of children, whose bones are still growing. It is important to have significant pain and/or disability prior to considering this procedure. Because the replacement parts can break down over time, and healthcare providers generally recommend delaying knee replacement until it is absolutely necessary.
Approximately 700,000 knee replacement procedures are performed annually in the US. This number is projected to increase to 3.48 million procedures per year by 2030.
Alternatives to Knee Replacement
While total knee replacement can be helpful under the right circumstances, you should discuss the risks, benefits, and alternatives with a doctor. Alternatives to total knee replacement include:
Nonsurgical treatment — Nonsurgical treatment methods are initially recommended for patients with osteoarthritis or inflammatory arthritis.
- Weight loss. The knee sees about four pounds of pressure for each pound of body weight, so even a small amount of weight loss (eg, 10 to 15 lbs) can lead to reduced pain.
- Exercise/physical therapy. Strengthening the muscles around the knee help take pressure off the knee. A motion of the joint helps to keep it from getting stiff.
- Medications, including over-the-counter and prescription. These include pain relievers such as acetaminophen and antiinflammatory drugs such as ibuprofen or naproxen. Patients should discuss use of these medications with their primary care provider and pharmacist to be sure the risk of side effects is acceptably low.
- Knee bracing or shoe inserts, both of which may help align the knee and balance the weight on the joint. Injections, either with a cortisone-like drug or a hyaluronic acid derivative.
- Arthroscopy is a minimally invasive surgical procedure in which a doctor examines the inside of a joint with a device called an arthroscope. The doctor can repair any damage through small surgical incisions in the skin.
- Arthroscopy is only helpful for a certain type of knee problems. Arthroscopic surgery has not demonstrated a significant benefit for patients with osteoarthritis.
- Osteotomy is a surgical procedure that involves cutting the leg bone, realigning it, and allowing it to heal. It is used to shift weight from a damaged part of the knee to a normal or less damaged one.
- Osteotomy is not recommended for patients older than 60 years of age or for those with inflammatory arthritis (such as rheumatoid arthritis).
Partial knee replacement
- A “partial” or unicompartmental knee replacement involves replacing only one part of the knee joint.
- There is are debate about the benefit of partial knee replacement compared with total knee replacement, but some studies have shown favorable results .
Procedures of Knee Replacement
Knee replacement is performed in an operating room after you are given anaesthesia. The surgery takes two to three hours. After surgery, you will be monitored in a recovery area for several hours, until the effects of the anaesthesia wear off.
Most people stay in the hospital for one to four nights after surgery, although shorter stays are becoming more common. During this time, you will be given pain medicines.
Blood clots in the legs (called deep vein thromboses) are a common concern after knee replacement surgery.
To reduce the risk of blood clots:
- Mobilize early. Work with your physical therapist to try and get up the day of surgery or the day after. Learn exercises to do while in bed.
- You will take a medicine, either as a pill or a shot. Most patients continue to take this medicine for a few weeks after surgery.
- You will need to wear compression boots (devices that go around the legs and inflate periodically) while you are lying down.
- Once you are able to get up and walk, you will wear antiembolism stockings.
- These stockings fit snugly around the foot, ankle, lower leg, and knee to help prevent blood clots.
- Infection is another major concern, and you will be given antibiotics within an hour of the procedure and for up to 24 hours after.
- Eating a healthy diet, avoiding obesity, and smoking cessation all are helpful for minimizing infection risk.
- You will be encouraged to start moving your feet and ankles immediately after surgery. Some surgeons use a continuous passive motion device, which raises and slowly moves your leg while you are in bed. It is common to begin physical therapy the day of or one day after surgery, while you are still in the hospital.
- Physical therapy is an important part of the recovery process. After leaving the hospital, some people have physical therapy in their home or at a clinic, while others stay in a rehabilitation facility or nursing home for a few days.
- The rehabilitation program generally includes exercises to improve range of motion (how far you can bend and straighten your knee) and to strengthen your leg muscles. Your surgeon and physical therapist will help to set goals as you progress through rehabilitation.
- The goal of the rehabilitation period is to regain strength and movement in the knee; it is important to avoid overworking or straining the knee during this recovery period. You can usually resume your normal activities within three to six weeks after surgery.
- After several months of rehabilitation, you will be able to have a more active lifestyle. High-impact sports such as running and sports that involve heavy contact (football) are not recommended, but you should be able to participate in activities like walking, bicycling, and swimming.
Serious complications are not common after knee replacement. However, it is important to be aware of the major potential complications. Studies have shown that a successful joint replacement partially depends upon the experience of the surgeon and the hospital. In one study, outcomes were better in people who had:
A surgeon who performed more than six knee replacements each year Surgery performed in a hospital where more than 25 joint replacements were performed per year.
Better outcomes included better knee function and lower rates of complications after surgery.
Blood clot: Having total knee replacement increases the risk of a blood clot forming in a vein (called a thrombosis). The most common place for a thrombosis to develop after knee surgery is in the deep veins of the leg (called a deep vein thrombosis [DVT]). Symptoms of a DVT include leg pain and swelling. Call your doctor's office if you are worried that you could have a DVT.
Infection: Infection following knee replacement is a relatively uncommon but serious complication. Signs of infection include fever, chills, pain in the knee that gets worse suddenly, increasing redness, or swelling. Call your doctor's office if you are worried that you could have an infection. Wound infections are treated with antibiotics and occasionally by draining excess fluid from the joint. If an infection becomes deep or extensive, the prosthetic joint may need to be removed and reimplanted later, after the infection has cleared.
Stiffness: Occasionally, despite physical therapy, a patient’s knee may get stiff and may not bend or straighten properly. If this occurs, then the patient may return to the operating room in order to bend and/or straighten the knee under anaesthesia.
Early failure: Although most studies demonstrate that 80 to 90 per cent of total knees will last between 15 to 20 years, early failures may occur due to a variety of reasons. These include loosening of the implants, infection, fractures of the bone around the implants, and instability. When early failures occur, revision surgery may be necessary.
Symptoms of condition treated by Knee Replacement
1. Pain related issues
- Pain with activity.
- Knee Pain manifests in many ways. Pain that comes on with activity and limits what you can do is a clear signal to seek help.
- Delayed pain.
- Pain doesn’t have to stop you in your tracks to be serious. Pain that comes on after activity, also known as ‘payback pain’, can be a warning that your knee isn’t performing as it should.
- Pain that interrupts sleep.
- If you find knee pain prevents you from falling asleep or you wake up because of pain caused by your movements during sleep – talk to someone about it.
2. Visual changes to the knees
- The way your knee looks can be just as important as the way it feels. Changes in the appearance of your knee can be a sign of inflammation. If your leg swells, or looks markedly different from the other then it may be time to speak with a specialist.
3. Limited movement around the joints
- Difficulty sitting down in a low seat such as in a car or cinema because your knee refuses to bend is a common sign of osteoarthritis. Seizing or catching of the joint during movement can also indicate advanced deterioration or that a loose bone fragment has become lodged in the joint.
4. Lifestyle limitations
- It doesn’t matter if you want to climb a mountain or simply prune the garden - any symptom that prevents or limits your ability to do the things you love is cause for concern. With a little help, a bad knee doesn’t have to impact your quality of life.