Knee Replacement surgery is the process of replacing the damaged kneecap, thighbone and shinbone with artificial plastic material and metal alloys.
The surgery is conducted by an experienced orthopedic surgeon and involves intricate bone recreation processes. The captella or kneecap is mainly restructured in the surgery using a knee prosthesis which is made up of a combination of metal and plastics. In most cases, artificial knee joint is able to replicate the abilities of natural knee joint.
Knee Replacement surgery is also called TKR (Total Knee Replacement) or Knee Arthroplasty.
There are two main physical reasons that lead to a knee arthroplasty.
- The first reason is acute osteoarthritis which leads to drying up of the cartilage and partial damage to its structure as a knee cap. This degenerative disease slowly eats away at the original complete structure of the knee joint and therefore, requires knee replacement surgery to fight the condition. Acute cases of osteoarthritis may require resurfacing of thigh or leg bones damaged by the disease. In such cases, the surgeon restructures the joint area by conjoining artificial and original parts to create complete bones and knee cap. In addition to osteoarthritis knee, rheumatoid arthritis and post traumatic arthritis.
- The second reason that leads to knee arthroplasty surgery is accidental damage to the knee area which may be caused by falls or crashes. Old people are specially susceptible to falls down the stairs or on slippery floors and suffer broken knee joints or knee caps. Acute knee injuries also occur in automobile crashes where many injured parts of the knee joint are removed and replaced with artificial prosthesis.
The following tests are most important before a knee replacement surgery is scheduled.
- Complete physical examination of the bone structure of the affected area and its surroundings. Specific pain related tests that include pricking and rubber hammering at specific points determine exact cause of pain and nerve condition. Ability to move the limb is tested to check seriousness of disability. Medications prescribed to correct the condition are checked to see if working.
- The injured knee will be evaluated using X ray studies from all axes to help the surgeon determine the extent of damage to the joint. Multiple X ray reports also help the orthopedic determine any abnormalities in joint shape and structure by comparing with X rays of the other knee joint.
- Blood tests will be done to determine tolerance in your body and detect any chances of infection causing organisms occurring in your blood. If any infection is detected, then treatment to remove the infection is completed before the surgery is scheduled.
- Other Diagnostic Tests: These include check-ups of blood pressure, urine and stool tests, ad any specific test to allergies that may be required in specific cases.
You should report any condition of hyper allergy or uncontrollable blood loss to the doctor before surgery.
Knee replacement surgery lasts about 2 to 3 hours. Following are the steps of the procedure:
- You will be asked to change into an operating gown and lie down on the operating table. An IV line is administered on your arm. The skin over the injured knee is thoroughly cleaned with sterilized cotton to remove all chances of infection.
- The procedure is performed under general or spinal anesthesia, as per your preference. Heart rate, blood oxygen level, blood pressure and breathing will be regularly monitored.
- The surgeon makes a strategic incision of 15 to 25 cms above the joint area to part the upper layers of the skin and expose the knee joint. Damaged areas of the joint including parts of the knee cap and bones are removed.
- Using a prosthesis that resembles the damaged knee cap and tibia and femural elements in shape, the knee cap is slowly recreated around the restructured tibia and the femur ends, thus completing the knee joint.
- The patellar portion, which is the lower end of the knee cap that rubs against the femur, is also restructured using prosthesis and this completes the entire knee joint. Parts of the bone that may have broken or chipped off due to accidental injuries are also recreated using similar prosthesis.
- In most cases, cemented prosthesis, that attaches to the bone with a surgical cement, is used as it is more reliable than uncemented prosthesis, that attaches to the bone surface using a porous surface. In rare cases, both versions of attachment in prosthesis are used.
- The incision is closed using surgical staples or stitches.
You will be required to stay in the hospital for 2 to 3 days, after the procedure. During your stay you will be made to do certain leg exercises that will help improve flow of blood in the leg.
Once you are back to your home, the following care is highly important:
- Under the supervision of a trained physiotherapist, you will be required to exercise and move the knee joint area. This process starts when you are admitted in the hospital after the procedure and continues even after you have been discharged and are at home. The physiotherapist monitors the improvement in muscle and nerve control at the new joint and reports in cases of any swelling or soreness.
- The operated area needs to be kept dry and clean and at no cost should there be any external damage to the stitches. The doctor provides with specific bath instructions and maintains the instructions till the staples or stitches are removed. Presence of moisture around the incision can lead to fluid accumulation and pus formation at the stitches which can increase chances of infection.
- In case of swelling at the knee joint, you will be asked to raise his leg and apply ice packs.
- In case of soreness, a light dose of physiotherapy is advised and use of medication to obtain pain relief is allowed only to the extent that the medicines do not cause further bleeding. Therefore, aspirin and similar pain relievers are not prescribed in this condition.
- Fever, redness, or pain at or near the incision point must be reported to the doctor immediately. It is also important to take steps to reduce chances of pneumonia.
- Other post operative care includes use of cane or walker to assist in walking till balance and muscle control is achieved completely.
- You will be asked to use handrails while climbing stairs and walking long distances and use shower benches and long handle sponges or showers to reduce bending at the knee area while bathing.
You will be able to resume your normal routine 4 to 6 weeks and experience better mobility after the knee replacement surgery. However, activities like jogging, jumping, skipping or sports activities should be minimized.
Although knee replacement surgery is carried out in highly sterile and monitored conditions by experienced orthopedic surgeons, there are chances of complications that may arise during or after the procedure. These include:
- excessive bleeding of internal tissues or at incision point,
- infection at the incision,
- occurrence of blood clots in lungs or legs,
- prosthesis loosening or wearing out,
- fracture at the knee joint due to wrong placement or movement,
- chronic pain and stiffness at the operated area.
In addition to these serious problems, the replacement knee joint might get dislodged or loosened after few days.
In cases of faulty placements, the knee joint may fail to function in the way it is expected to and may need to go through another surgery.
During the operation, nerves and blood vessels around the area might be damaged and this could lead to numbness and weakness at the knee area. Knee pain and weakness in the operated area, that cannot be corrected through surgery, may require long term medication and physiotherapy.