The main difference between a fixed-bearing, or traditional knee replacement, and a mobile-bearing knee is that the articulating surface is free to rotate slightly along with the patient’s natural movement.

“The design of this knee allows for better range of motion and improved flexibility for daily activities, whether around the home, at work or during sports and exercise,” says Dr. Sheinkop (www.neuro-ortho.org/find-doctor/sheinkop-bio.htm), an orthopedic surgeon and Director of Joint Replacement at the NOHC (www.neuro-ortho.org/orthopedic/joint-replacement.htm). “The knee is designed for patients who want high flexion and have demanding lifestyles/habits. If you want to do deep knee bends, this is the knee you should choose.”

Just ask athlete and lawyer Charles Zarzecki, who has a “work hard, play hard” mentality. Zarzecki, age 50, participated in the clinical trial for the NexGen ® LPS-Flex mobile bearing knee and now plays in a Chicago-based USA Hockey team that placed 2nd in the 2007 National Pond Hockey Championships.

‘In 2004, I was playing competitive basketball and there was little cartilage left in my knee,” says Zarzecki. “After four arthroscopic surgeries, my leg still bowed out, and I knew it was time to do something if I wanted to continue my active lifestyle. Dr. Sheinkop encouraged me to try the mobile-bearing knee because I love playing competitive sports. Without this new knee, I would not be playing hockey today." Besides hockey, Zarzecki’s knee allows him to participate in golfing, biking, spinning and snow skiing.

In 2001, Dr. Sheinkop was first exposed to the mobile-bearing knee through an invitation from the Ministry of Health for the United Arab Emirates. At that time he recognized the impact a high-performance prosthesis could have on his athletic patients back at home.

The knee is the largest joint in the body, and one of the most easily injured. It is made up of the lower end of the thighbone (femur), which rotates on the upper end of the shinbone (tibia), and the knee cap (patella), which slides in a groove on the end of the femur. The knee also contains large ligaments, which help control motion by connecting bones and by bracing the joint against abnormal types of motion. Another important structure, the meniscus, is a wedge of soft cartilage between the femur and tibia that serves to cushion the knee and helps it absorb shock during motion. The long thigh muscles give the knee strength.

The joint surfaces where these three bones touch are covered with articular cartilage, a smooth substance that cushions the bones and enables them to move easily. All remaining surfaces of the knee are covered by a thin, smooth tissue liner called the synovial membrane. This membrane releases a special fluid that lubricates the knee, reducing friction to nearly zero in a healthy knee. Normally, all of these components work in harmony. But disease or injury can disrupt this harmony, resulting in pain, muscle weakness, and reduced function.

Many different types of designs and materials are currently used in total knee replacement surgery, nearly all of which consist of three components: the femoral component, the tibial component, and the patellar component. Today’s standard knee replacement only offers between 115-120 degrees of motion and as a result, patients complain of permanent stiffness post-surgery. Through the mobile-bearing knee, patients can achieve up to 135 degrees of flexion motion, allowing for a more level gait, the ability to squat, stoop, climb stairs, etc. This enhanced motion allows for the active patient to continue playing sports at a pre-surgical high-performance level.