What is Bilateral Knee Replacement?
Bilateral knee replacement, also called bilateral knee arthroplasty, is a surgical procedure in which the worn out or damaged surfaces of both knees are removed and replaced with artificial prostheses. Artificial knee joints are usually made of metal, ceramic, or plastic and consist of the femoral and the tibial components.
There are 2 types of bilateral knee replacement: simultaneous bilateral total knee replacement and staged bilateral total knee replacement.
Simultaneous bilateral total knee replacement involves replacing both knees with a prosthesis under one operation, one anaesthesia, and on the same day. This means one hospital stay and one rehabilitation phase. Usually, young and active individuals who are non-obese and healthy are treated with a simultaneous bilateral knee replacement.
Staged bilateral total knee replacement refers to performing both knee replacements under 2 separate surgical interventions that are spread several months apart. This means 2 hospitalizations, 2 occasions of anaesthesia, and 2 recovery phases. Usually, obese and/or elderly people and those with significant medical conditions are treated with a staged bilateral knee replacement.
Anatomy of the Knee Joint
The lower end of the thighbone, or femur, meets the upper end of the shinbone, or tibia, at the knee joint. A small disk of bone called the patella, commonly known as the kneecap, rests on a groove on the front side of the femoral end. The bones are held together by protective tissues, ligaments, tendons, and muscles. Synovial fluid within the joint aids in the smooth movement of the bones over one another. The meniscus, a soft crescent-shaped area of cartilage between the femur and tibia, serves as a cushion and helps absorb shock during motion.
Indications for Bilateral Knee Replacement
Bilateral knee replacement surgery is commonly indicated for severe osteoarthritis of the knee. Osteoarthritis is the most common form of knee arthritis in which the joint cartilage gradually wears away. It often affects older people.
In a normal joint, articular cartilage allows for smooth movement within the joint, whereas in an arthritic knee the cartilage itself becomes thinner or completely absent. In addition, the bones become thicker around the edges of the joint and may form bony “spurs.” All of these factors can cause pain and restricted range of motion in the joint.
Your doctor may advise bilateral knee replacement if you have:
- Severe knee pain which limits your daily activities (such as walking, getting up from a chair, or climbing stairs).
- Chronic knee inflammation and swelling
- Knee deformity with loss of cartilage and pain
- Injury or fracture of the knee
- Instability of the knee
- Moderate to severe pain that occurs during rest or awakens you at night
- Failure of the non-surgical treatment options such as medications, injections, and physical therapy to relieve symptoms
Preparation for Bilateral Knee Replacement
Preoperative preparation for bilateral knee replacement will involve the following steps:
- A thorough examination by your doctor is performed to check for any medical issues that need to be addressed prior to surgery.
- Depending on your medical history, social history, and age, you may need to undergo tests such as bloodwork and imaging to screen for any abnormalities that could threaten the safety of the procedure.
- You will be asked if you have allergies to medications, anaesthesia, or latex.
- You should inform your doctor of any medications, vitamins, or supplements that you are taking.
- You should refrain from medications or supplements such as blood thinners, aspirin, or anti-inflammatory medicines for 1 to 2 weeks prior to surgery.
- You should refrain from alcohol or tobacco at least a week before and 2 weeks after surgery.
- You should not consume solids or liquids at least 8 hours prior to surgery.
- Arrange for someone to drive you home after surgery.
- A written consent will be obtained from you after the surgical procedure has been explained in detail.
Procedure for Bilateral Knee Replacement
Based on your age and health factors, your surgeon will decide on the best treatment approach for you.
The surgery is performed under regional or general anaesthesia. Your surgeon will make an incision in the skin over the affected knee to expose the knee joint. Then, the damaged portions of the femur bone are cut at appropriate angles using specialised jigs. The femoral component is attached to the end of the femur with or without bone cement.
Your surgeon then cuts or shaves the damaged area of the tibia and the cartilage. This removes the deformed part of the bone and any bony growths, as well as creates a smooth surface on which the implants can be attached. Next, the tibial component is secured to the end of the bone with bone cement or screws.
Your surgeon will place a plastic piece called an articular surface between the implants to provide a smooth gliding surface for movement. This plastic insert will support the body’s weight and allow the femur to move over the tibia like the original meniscus cartilage.
The femur and the tibia with the new components are then put together to form the new knee joint.
To make sure the patella glides smoothly over the new artificial knee, its rear surface is also prepared to receive a plastic component.
With all the new components in place, the knee joint is tested through its range of motion. Finally, the incisions are closed with sutures and sterile dressings are applied.
Postoperative Care and Instructions
In general, postoperative care instructions and recovery after bilateral knee replacement will involve the following:
- You will be transferred to the recovery area where your nurse will closely observe you for any allergic or anaesthetic reactions and monitor your vital signs as you recover.
- You may notice pain, swelling, and discomfort in the knee area. Pain and anti-inflammatory medications are provided as needed.
- You are advised to keep your leg elevated while resting to prevent swelling and pain.
- You will be given assistive devices such as crutches with instructions on restricted weight-bearing for a specified period of time. You are encouraged to walk with assistance as frequently as possible to prevent blood clots.
- Keep the surgical site clean and dry. Instructions on surgical site care and bathing will be provided.
- Refrain from smoking as it can negatively affect the healing process.
- Eating a healthy diet rich in vitamin D is strongly advised to promote healing and a faster recovery.
- Refrain from strenuous activities for the first few months and lifting heavy weights for at least 6 months. Gradual increase in activities over a period of time is recommended.
- An individualised physical therapy protocol will be designed to help strengthen knee muscles and optimise knee function.
- Most patients can resume their normal activities in a month or two after surgery; however, return to sports may take at least 6 months or longer.
- Refrain from driving until you are fully fit and receive your doctor’s consent.
- A periodic follow-up appointment will be scheduled to monitor your progress.
Risks and Complications
Bilateral knee replacement surgery is a relatively safe procedure; however, as with any surgery, some risks and complications may occur, such as the following:
- Blood clots
- Anaesthetic/allergic reactions
- Injury to nerves and blood vessels
- Implant wear and loosening
- Failure to relieve knee pain or stiffness
- The need for revision surgery