What is Muscle Sparing Total Knee Replacement?
A total knee replacement surgery involves replacing the damaged surfaces of the articulating bones with artificial implants to relieve pain and restore function in the knee that is damaged by arthritis or an injury.
Muscle sparing total knee replacement is a minimally invasive surgical approach that involves making a smaller incision of 4 to 6 inches in length as compared to a larger incision of 10 to 12 inches used in the traditional knee replacement and spares the quadriceps muscle and tendon, which control bending of the knee, from being cut to access the knee joint.
The quadriceps muscles are the muscles located in front of the thigh. The quadriceps tendon is a thick tissue located at the top of the kneecap. It works together with the quadriceps muscles to allow us to straighten our legs.
The smaller incision with minimally invasive surgery means fewer tissues are cut resulting in quicker healing and recovery. The advantages of muscle sparing total knee replacement over traditional knee replacement include:
- Minimal surgical dissection
- Shorter recovery period
- Shorter hospital stay
- Reduced post-operative pain
- Minimal blood loss
- Smaller surgical scar
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 disc 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 Muscle Sparing Total Knee Replacement
Muscle sparing total 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 muscle sparing total knee replacement if you have:
- Severe knee pain that 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 Muscle Sparing Total Knee Replacement
Preoperative preparation for muscle sparing total 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, anesthesia, 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 Muscle Sparing Total Knee Replacement
Muscle sparing total knee replacement surgery is performed under regional or general anesthesia and involves the following steps:
- You will be lying on your back on the operating table with a tourniquet applied to your upper thigh to reduce blood loss.
- Your surgeon will then make a 4-6 inch incision along the affected knee to expose the knee joint. The quadriceps muscle and tendon are moved aside to access the joint.
- The surgeon first focuses on the femur (thighbone). The damaged portions of the femur are cut at the appropriate angles using specialized tools.
- Then the femoral component is attached to the end of the femur with or without bone cement. The next step involves removal of the damaged area of the tibia (shinbone) and the cartilage. It allows for a smooth surface to which implants can be attached.
- The tibial component is then secured to the end of the bone using bone cement or screws. Your surgeon will place a plastic piece called an articular surface between these implants to ensure a smooth gliding movement.
- This plastic insert acts in a similar way as the original articular cartilage and helps in supporting your body weight as well as allows the femur bone to move over the tibia. The femur and the tibia bone with their new components are put together to form the new knee joint.
- To ensure that the patella (kneecap) glides smoothly over the new artificial knee, its rear surface is prepared to receive a plastic component. With all its new components in place, the knee joint is examined through its range of motion.
- All excess cement will be removed, and the entire joint will be irrigated or cleaned out with a sterile saline solution.
- The incision is then closed and drains are usually inserted. A surgical dressing or bandage is then placed over the incision.
Postoperative Care and Instructions
In general, postoperative care instructions and recovery after muscle sparing total knee replacement surgery will involve the following:
- You will be transferred to the recovery area where your nurse will closely observe you for any allergic or anesthetic 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 individualized physical therapy protocol will be designed to help strengthen knee muscles and optimize knee function.
- Most patients are able to 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
Muscle sparing total 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
- Anesthetic/allergic reactions
- Injury to nerves and blood vessels
- Implant wear and loosening
- Failure to relieve knee pain or stiffness
- The need for revision surgery