Partial knee replacement

Anatomy

The knee is a hinge joint, meaning it can only bend in one direction, and is where the tibia, the femur, and the patella meet. Like most joints in the body, the knee has a dense, fibrous, connective tissue, known as articular cartilage, that seals the joint space between the femur and tibia, and prevents the bones from rubbing against each other. The articular cartilage acts as a shock absorber and allows for smooth and stable movement. It is divided into three major compartments:

• The inside part of the knee (Medial compartment)
• The outside part of the knee (Lateral compartment)
• The front of the knee between the kneecap and thighbone (Patellofemoral compartment)

About

Over time, the articular cartilage within the knee joint can wear down, resulting in a condition known as osteoarthritis. When the cartilage thins, the joint can inflame causing pain, stiffness, and a limited range of motion. Advanced osteoarthritis limited to a single compartment of the knee may be treated with partial knee replacement. The procedure allows for the damaged compartment to be replaced with artificial parts while the healthy compartments of the knee are preserved. Partial knee replacements can offer the following potential benefits over full knee replacements:

• Quicker recovery
• Less pain after surgery
• Less blood loss
• A more natural feeling knee

The only downside to the procedure is if other compartments of the knee deteriorate in the future, more procedures may be necessary.

Symptoms

Knee osteoarthritis can result in severe and chronic pain. Symptoms depend on the severity of the injury.

General symptoms include:

• Pain that increases with activity, but only gets slightly better with rest
• Swelling
• Feeling of warmth in the joint
• Stiffness in the knee, especially in the morning or after sitting for long periods of time
• Decrease in mobility of the knee, making it difficult to get in and out of chairs or cars, use the stairs, or walk
• Creaking, crackly sound that is heard when the knee moves

Diagnosis

Your Florida Orthopaedic Institute physician will evaluate your symptoms and determine the cause of your pain. X-rays may be taken, which can show cartilage and bone damage, as well as the presence of bone spurs. MRI scans may be ordered if the X-rays do not give a definite reason for joint pain, or when the X-ray depicts that other types of joint tissue could be damaged. Blood tests may also be used to rule out other conditions that could potentially be causing the pain.

Treatment

Depending on the severity of the articular cartilage, your physician may recommend a partial knee replacement. The Florida Orthopaedic Institute takes advantage of two surgical robots, NAVIO and MAKO, ensuring a more precise surgical process.

The NAVIO Surgical System is a robotics-assisted navigation technology used to achieve precise positioning of the knee implant for consistently accurate results. During the procedure, the surgeon collects anatomical data using an X-ray to build a 3-D model of the patient’s knee, allowing the surgeon to place the implant and balance the knee’s ligaments for optimal alignment and a well-balanced knee. NAVIO allows for surgeons to take the patient’s own unique anatomy and tailor the procedure to better suit the patient’s needs. Using NAVIO offers many benefits to the patient such as a smaller incision, less pain, quicker rehabilitation and recovery, more natural knee motion, and a lower risk of complications.

MAKO robotic-arm assisted surgery system is a robotic arm controlled by the surgeon that enables accurate alignment and placement of implants. The technology provides the surgeon with a patient-specific 3-D model to pre-plan your partial knee replacement. A CT scan of your joint is taken, which is used to create the 3-D virtual model of your unique anatomy. The virtual model is then loaded into the MAKO system software and is used to create your personalized pre-operative plan. 

These technologies are used to complete the three basic steps to the procedure. These steps include:

• Preparing the bone – Your surgeon will use special saws to remove the cartilage from the damaged compartment of your knee
• Positioning the metal implants
• Inserting a spacer –  A plastic insert is placed between the two metal components to create a smooth gliding surface

Recovery

Partial knee replacements take approximately six weeks of recovery. Recovery from this procedure requires rehabilitation exercises. Immediately after surgery, you will be putting weight on your knee, usually with the help of a walker, cane, or crutches. A physical therapist will give you exercises to help maintain your range of motion and restore your strength. Fortunately, because a partial knee replacement is done through a smaller incision, patients usually have a shorter recovery period as compared to full knee replacement surgery. Follow your doctor’s care instructions for a smooth recovery.

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