Total Knee Replacement

Total knee replacement, also called total knee arthroplasty, is a surgical procedure in which the worn out or damaged surfaces of the knee joint are removed and replaced with artificial parts. The knee is made up of the femur (thigh bone), the tibia (shin bone), and patella (kneecap). The meniscus, the soft cartilage between the femur and tibia, serves as a cushion and helps absorb shock during motion. Arthritis (inflammation of the joints), injury, or other diseases of the joint can damage this protective layer of cartilage, causing extreme pain and difficulty in performing daily activities. Your doctor may recommend surgery if non-surgical treatment options have failed to relieve the symptoms.

Indications

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”. These factors can cause pain and restricted range of motion in the joint.

Your doctor may advise total knee replacement if you have:

• Severe knee pain which limits your daily activities (such as walking, getting up from a chair or climbing stairs).
• Moderate to severe pain that occurs during rest or awakens you at night.
• Chronic knee inflammation and swelling that is not relieved with rest or medications
• Failure to obtain pain relief from medications, injections, physical therapy, or other conservative treatments.
• A bow- legged knee deformity

Causes

The exact cause of osteoarthritis is not known, however there are several factors that are commonly associated with the onset of arthritis and may include:

• Injury or trauma to the joint
• Fractures at the knee joint
• Increased body weight
• Repetitive overuse
• Joint infection
• Inflammation of the joint
• Connective tissue disorders

Diagnosis

Your doctor will diagnose osteoarthritis based on the medical history, physical examination, and X-rays.

X-rays typically show a narrowing of the joint space in the arthritic knee.

Procedure

The goal of total knee replacement surgery is to relieve pain and restore the alignment and function of your knee.

The surgery is performed under spinal or general anesthesia. 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 specialized jigs. The femoral component is attached to the end of the femur with or without bone cement. The surgeon then cuts or shaves the damaged area of the tibia (shinbone) 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 (knee cap) 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. The entire joint is then irrigated and cleaned with a sterile solution. The incision is carefully closed; drains are inserted and a sterile dressing is placed over the incision.

Post-operative care

Rehabilitation begins immediately following the surgery. A physical therapist will teach you specific exercises to strengthen your leg and restore knee movement. Knee immobilizers are used to stabilize the knee. You will be able to walk with crutches or a walker. A continuous passive motion (CPM) machine can be used to move the knee joint. Continuous passive motion is a device attached to the treated leg which constantly moves the joint through a controlled range of motion, while the patient relaxes. Your physical therapist will also provide you with a home exercise program to strengthen thigh and calf muscles.

Risks and complications

As with any major surgery, possible risks and complications associated with total knee replacement surgery include:

• Knee stiffness
• Infection
• Blood clots (deep vein thrombosis)
• Nerve and blood vessel damage
• Ligament injuries
• Patella (kneecap) dislocation
• Plastic liner wears out
• Loosening of the implant

If you find difficulty in performing simple activities such as walking or climbing stairs because of your severe arthritic knee pain, then total knee replacement may be an option for you. It is a safe and effective procedure to relieve pain, correct leg deformity, and help you resume your normal activities of daily living.

VERASENSE^TM

VERASENSE^TM Sensor-Assisted Total Knee Replacement

VERASENSE ™, a wireless orthopaedic sensor device used during primary and revision total knee replacement (TKR), enables surgeons to make evidence-based decisions on soft tissue balance and implant position - two factors that can improve patient outcomes. ^1,2

Benefits of Sensor-Assisted TKR

Patients whose knees were balanced using VERASENSE Sensor-Assisted TKR have shown statistically significant improvements over patients whose knees were left unbalanced. Patients whose surgeon uses VERASENSE sensor-assisted technology during primary or revision TKR may experience:

• Less Pain
• Quicker return to normal activity
• Improved knee function
• Improved patient satisfaction1,2

How Does VERASENSE Work?

The disposable sensor device leverages technology similar to those used in smartphones and gaming applications. TKR is a common procedure, but before VERASENSE, surgeons generally relied on their “best judgment” in determining what “felt” like a balanced knee.

During your TKR procedure, your surgeon uses VERASENSE to replace the standard tibial trial spacer. As the knee is taken through a full range of motion, the sensor sends data wirelessly to a monitor in the operating room, which provides information on compartmental loads within your knee. With the use of the the real-time data from the sensor, VERASENSE aids in your surgeon’s decision-making about soft tissue adjustments and implant position. Improper soft tissue balance and implant position may result in premature implant failure and the need for revision surgery in the future. ^3-6

VERASENSE does not change surgical workflow or a surgeon’s decision on which implant design would be best for you. The procedure is the same, but with the use of the intraoperative data from this sensor device, surgeons aim to improve the balance and stability of your knee, allowing for improved patient outcomes when compared to a traditional TKR and the potential for a longer lifespan of your knee implant. ^1-6

VERASENSE Animation:

OrthoSensor VERASENSE Overview: Benefits of Sensor-Assisted Knee Replacement Surgery from OrthoSensor, Inc. on Vimeo.

For more information about the use of VERASENSE in total knee replacement, call HOUSTON OFFICE 346.571.7500

VERASENSE is manufactured by OrthoSensor, Inc.

References:

1. Gustke KA, et al. Primary TKA patients with Quantifiably Balanced Soft-Tissue Achieve Significant Clinical Gains Sooner than Unbalanced Patients. Adv Orthop. 2014:628695.

2. Gustke K, et al. Increased Patient Satisfaction After Total Knee replacement using sensor-guided technology. Bone Joint J. 2014 Oct;96-B(10):1333- 8.

3. Parratte S, Pagnano MW. Instability after total knee arthroplasty. J Bone Joint Surg Am 2008; 90: 184–94.

4. Lombardi AV Jr1, Berend KR1, Adams JB1. Why knee replacements fail in 2013: patient, surgeon, or implant? Bone Joint J. 2014 Nov;96-B(11 Supple A):101-4.

5. Bozic KJ, Kurtz SM, Lau E, Ong K, Chiu V, Vail TP, Rubash HE, Berry DJ. The epidemiology of revision total knee arthroplasty in the United States. Clin Orthop Relat Res.2010; 468(1):45–51.

6. Rodriguez-Merchan, EC. Instability Following Total Knee Arthroplasty. HSS J. Oct 2011; 7(3): 273–278.