Hip Replacement
Hip replacement surgery removes the arthritic ball of the upper femur (thighbone) as well as the damaged cartilage from the hip socket. The ball is replaced by a metal or ceramic ball that is solidly fixed to a stem inserted into the femur. The socket is replaced with a metal cup, which is fixed to the acetabulum, or socket. The implants are designed to create a new, smoothly functioning joint that prevents painful bone-on-bone contact.
Cemented vs. Cement-Free Components
In total hip joint replacement, the femoral component can be secured to your body in one of two ways: using bone cement as a grout to affix the components to your bone, or using a "cementless" component that is specially designed to allow your own bone to grow into the surface of the implant. Which component your surgeon chooses for you will depend on a variety of factors, including the condition of your bone tissue. In the United States, the majority of patients receive cement-free implants.
Porous Coating
Porous Coating Allows Bone to Grow into the Stem
For the cementless femoral component to be stabilized, bone must grow into the stem. OMNIlife science applies a coating of titanium alloy to its cementless stems, Using a porous plasma spray known as CP-Ti. While many implant manufacturers use a porous coating process of some sort, OMNIlife science uses plasma sprayed titanium alloy exclusively on all its cementless stem implants. OMNIlife science chose this coating process because it provides several advantages, including:
- Implant Strength
- Surface Roughness that Promotes a Tight Fit
Femoral and Acetabular Components
The Shape and Sizing of the Femoral Implant Promotes Excellent Matching of Your Anatomy
OMNIlife science pioneered the use of tapered stems in total hip replacement in the United States. The goal of the stem’s design and shape is for it to wedge tightly near the top of the femur, reducing the potential for motion between the stem and the bone, which can cause pain. The inside of the femur in many patients is funnel-shaped, and the stem design reflects that shape, with the goal of creating a tight fit between the bone and the stem. The tapered design and line-to-line fit allow the stresses of walking and other activities to be transferred to the bone. It is important that the bone be stressed as you walk. Bone that is not stressed may atrophy and weaken. Additionally, OMNIlife science’s hip stems are offered in a wide range of size increments. By providing precise sizing options, OMNIlife science stems provide your surgeon with the best chance of achieving optimal fit. The femoral stem will be paired with an acetabular component, or socket, completing the "ball-and-socket" function of your hip. The vast majority of acetabular components implanted in the United States are implanted without cement and are designed to help promote bone in-growth fixation. Occasionally, a surgeon will use bone cement to affix a socket, depending on various factors, including the patient’s condition.
Polyethylene, Ceramic, or Metal
Your surgeon has several choices available in articulating surfaces. An articulating surface is where the motion of the joint actually occurs. In the case of the hip, it is where the head of the femoral component meets the acetabular socket. In order to provide smooth motion, the articulating surface must be able to withstand certain activities. Currently, polyethylene, metal-on-metal, and ceramic-on-ceramic are the most common articulating configurations offered. Each has its advantages and its place in the surgeon’s repertoire.
Polyethylene
Polyethylene (plastic) is an excellent material for hip articulation. It has been used in orthopaedic implants for decades. Polyethylene, however, can wear over time, generating debris in the joint. This debris can result in an immunological reaction known as osteolysis, which can result in the destruction of bone tissue and implant loosening. Not all patients will display osteolysis, even if polyethylene wear occurs. Newer methods of manufacturing polyethylene components, invented and patented by OMNIlife science, have resulted in significant intermediate-term improvements in durability.
Ceramic-on-Ceramic
Ceramic-on-ceramic implants are another option for total hip replacement. These implants are typically made from aluminum oxide, the second hardest known substance, and have shown excellent wear properties, making them suitable for long-term wear resistance.
Metal-on-Metal
Although hip implants are subject to wear over time, metal-on-metal hip implants are designed to withstand the higher demands of active lifestyles. These implants feature a metal ball that glides in a metal cup, which provides additional wear resistance. Metal-on-metal implants can also accommodate a larger femoral head than metal-on-polyethylene or ceramic-on-ceramic implants. This may reduce the risk of dislocation, increase range of motion and provide greater reduction in wear when compared to smaller implant heads.