Patient Education

Videos - American Academy of Orthopaedic Surgeons

Osteoarthritis of the Hip

Total Hip Replacement

Osteoarthritis of the Knee

Total Knee Replacement

Journey™ II - Total Knee Replacement

Implant Components

In the knee replacement procedure, each prosthesis is made up of four parts.

The tibial component has two elements – a metal base and a plastic insert – and replaces and the top of the tibia (shin bone). This prosthesis is made up of a metal tray attached directly to the bone and a high-density plastic spacer that provides the bearing surface.

The femoral component replaces the bottom of the thigh bone or femur. This component also replaces the groove where the patella or kneecap rides.

The patellar component replaces the surface of the knee cap, which rubs against the femur. The patella protects the joint, and the resurfaced patellar button will slide smoothly on the front of the joint. In some cases, surgeons do not resurface the patella.

Bearing Surfaces

One of the keys to a successful implant is its ability to withstand the rigors of daily activity, and central to that is the quality of the artificial surfaces that slide against each other, or articulate, in the new joint.

In knee implants, bearing surface options have been somewhat limited over the last few decades. The standard substance used for the femoral component is cobalt chrome, a metal alloy typified by its toughness and biocompatibility. However,even this high-quality industry standard has its shortcomings. Over time, this metal surface can become roughened by bone and bone cement particles trapped between the femoral component and the plastic tibial insert.

This roughened surface, when rubbing against the plastic component up to two million times per year, can more quickly wear out your implant. When that happens, you will have to undergo surgery to replace the plastic piece, the femoral component, and possibly even the tibial component. For this reason, implants have been shown to last between ten and fifteen years in the human body.

An exciting material to enter orthopaedics in recent years is OXINIUM◊ Oxidized Zirconium. This remarkable material combines the strengths of ceramic and metal, such as wear-reduction and strength, but does not have the weaknesses, such as limited implant options and the possibility of fracture.

Zirconium is a biocompatible metal, similar to titanium. When the zirconium alloy undergoes a unique heating process, the surface of the metal transforms into a ceramic. Even though the new ceramic surface is 4,900 times more abrasion resistant than cobalt chrome, it retains the toughness and flexibility of the underlying metal.

Because it can achieve this remarkable reduction in implant wear without sacrificing strength as actual ceramic components do, oxidized zirconium implants have the potential to last significantly longer.

The JOURNEY II BCS Knee

Recent advances in biomedical engineering software have opened a new chapter on high performance knee implants.

One remarkable breakthrough has been the creation of the JOURNEY II BCS knee, a second-generation knee replacement that combines the stability and natural motion of the human knee with new low-friction materials that may extend the life of the implant.

While the lifespan of a knee implant is heavily influenced by the materials used to make it, the natural feeling of the implant during physical activity is dependent upon the way the patient’s muscles, ligaments and tendons are addressed during surgery and by the implant’s shape within the body after surgery.

As discussed previously in this booklet, the knee is a hinge joint, but it does not swing like a simple door hinge. It has a complex rotational motion that you don’t notice is there – but many patients know when it’s not there after total knee replacement. Traditional implants attempt to recreate this subtle swing-and-rotate action with either a rotating platform (a simple pivot point) within the implant or by requiring an angled alignment of the implant during surgery.

With these traditional knee replacement designs, the muscles and ligaments around your new joint have to work harder because the implant’s slightly unnatural shapes and resulting motion make these soft tissues move in unfamiliar, stressful ways. This leads to joint pain, muscle fatigue and the unnatural feeling patients experience while walking or bending in the months after their procedure.

The JOURNEY II BCS knee, on the other hand, is designed to reproduce the original internal shapes and angled forces of the human knee through its full range of motion – accommodating the swing-and-rotate of the joint with the same engineering principles your real knee currently uses. Because of this, your soft tissues don’t have to readjust to new shapes and forces after surgery and your stride can return to its natural rhythm.

The JOURNEY II BCS knee also reproduces the stability provided by your anterior cruciate ligament (ACL) and your posterior cruciate ligament (PCL). Your ACL and PCL are key to the stability of your real joint and contribute to natural motion when your knee is fully extended and fully bent. No other knee implant reproduces both functions.

The Proceedure

Knee replacement surgery typically takes between one and two hours to complete. This section will provide you with a brief, easy-to-understand description of the surgical procedure. (Please consult with your physician for details regarding your specific procedure.)

  1. An incision is made extending from the thigh, past the inside edge of the kneecap, and down to the shinbone.

  2. The end of the femur is shaped in preparation for sizing the femoral trial component.

  3. The top of the tibia is shaped for proper sizing of the tibial trial component.

  4. The trial units are put in place and the appropriate implant size is selected.

  5. The knee is assessed for alignment, stability, and range of motion.

  6. The underside of the kneecap is prepared and patella trial is selected.

  7. The trial units are removed and the final femoral, tibial, and patella components are implanted.

  8. The incision is closed, a drain is put in, and the post-operative bandaging is applied.

Knee Bone Cuts
Knee Bone Cuts
Knee Implant components
Knee Implant components
Knee Implanted
Knee Implanted
Journey™ II - AKS Physiological Matching

Physiological Matching

The rationale behind the concept of Physiological Matching is simple: any change you make to the knee joint will ultimately impact the entire leg. Of course, as is so often the case, simple rarely means easy.

The primary hurdle to overcome in a knee replacement is the knee itself. Described as a hinge joint, the knee actually does much more than bend back and forth. In fact, every time your knee bends, forces in and around the knee cause it to move with a complex rotational motion that most of us never realize. However, when that motion is removed after knee replacement, the result can be disappointing.

Traditionally, most knee implants have attempted to replace the natural swing-and-rotate of the knee by building a simple pivot point into the implant (known as a rotating platform) or by using a slightly angled alignment of the implant during surgery. Unfortunately, both of these options can force the muscles and ligaments around the new joint to work harder and move in unfamiliar, stressful ways; resulting in pain, muscle fatigue and an unnatural feeling while walking or bending the knee.

The JOURNEY II implant was designed using Smith & Nephew’s proprietary LifeMOD human simulation software. This advanced software system allows engineers to examine in a virtual 3-D environment the exact internal shapes and angled forces that act on the knee throughout each phase of motion. As a result, the JOURNEY II implant has been designed to physiologically match how the hard structures of a normal knee joint move and rotate in an effort to maintain normal muscle activity and return the patient’s stride to it’s a natural rhythm.

Important Safety Notes:

Knee replacement surgery is intended to relieve knee pain and improve knee functions. However, implants may not produce the same feel or function as your original knee. There are potential risks with knee replacement surgery such as loosening, fracture, dislocation, wear and infection that may result in the need for additional surgery. Longevity of implants depends on many factors, such as types of activities and weight.

Do not perform high impact activities such as running and jumping unless your surgeon tells you the bone has healed and these activities are acceptable. Early device failure, breakage or loosening may occur if you do not follow your surgeon’s limitations on activity level. Early failure can happen if you do not guard your knee joint from overloading due to activity level, failure to control body weight or accidents such as falls. Talk to your doctor to determine what treatment may be best for you.

Journey II - AKS Implant Feel

The right “feel” often starts with the right design

To most of us, total knee implants all look very similar. With the exception of color (the OXINIUM  alloy used in JOURNEY II implants is black while the cobalt chrome used in other implants is silver), it can take an experienced eye to see the subtle differences in size and shape between two implants. However, as subtle as the differences may seem, they can often have a profound impact on how an implant feels to the patients after surgery.

Fortunately, JOURNEY II implants were designed using a concept called Physiological Matching◊. This unique process begins with proprietary human simulation software that virtually recreates the exact internal shapes and angled forces that act on the knee through each phase of motion. This detailed information helped Smith & Nephew engineers create an implant that replicates as closely as possible the complex, natural rotation of the knee.

Important Safety Notes:

Knee replacement surgery is intended to relieve knee pain and improve knee functions. However, implants may not produce the same feel or function as your original knee. There are potential risks with knee replacement surgery such as loosening, fracture, dislocation, wear and infection that may result in the need for additional surgery. Longevity of implants depends on many factors, such as types of activities and weight.

Do not perform high impact activities such as running and jumping unless your surgeon tells you the bone has healed and these activities are acceptable. Early device failure, breakage or loosening may occur if you do not follow your surgeon’s limitations on activity level. Early failure can happen if you do not guard your knee joint from overloading due to activity level, failure to control body weight or accidents such as falls. Talk to your doctor to determine what treatment may be best for you.

Journey™ II - AKS Implant Wear

Implant Materials Can Impact Durability

Virtually all total knee replacement systems use a combination of metal and plastic components to replace the surfaces of a damaged knee. Metal is typically used to replace the surfaces of the bone, while plastic is most commonly used to replace the joint’s cartilage.

Unfortunately, the metal and plastic surfaces of an implant can wear down over time. The primary cause of this “implant wear” is the friction created when the upper, metal, part of an implant – called the femoral component – rubs against the plastic insert. Even with pristine implants, over time, this friction can cause tiny particles of the insert to wear away. If the metal component becomes scratched for any reason, this destructive process can be increased dramatically. In fact, this type of implant wear is a leading cause of premature knee replacement failure.

Fortunately, implant wear can be offset by using advanced, wear-reducing materials during the creation of the implant.

VERILAST™  Technology

Unlike other implants that only available with cobalt chrome for their metal femoral components, the JOURNEY II Active Knee implant can also be made with a proprietary metal alloy called OXINIUM™  Oxidized Zirconium. While cobalt chrome has been used successfully for years, laboratory tests have shown that the “ceramicized” OXINIUM metal alloy is twice as hard as cobalt chrome and can be twice as resistant to the type of scratching that can cause implant wear. 1 First introduced in 1997, OXINIUM implants have been used in more than 1 million surgeries around the world.

And since each implant is a combination of metal and plastic, JOURNEY II implants also use a harder, highly cross-linked polyethylene known as XLPE for the plastic insert.

Working together, these materials form a bearing surface combination known as VERILAST Technology, which is unique to global medical device maker, Smith & Nephew.

Important Testing Note

VERILAST Technology has been designed to address “wear and tear,” which is only one reason why a knee implant may need to be replaced. Listen carefully when your orthopedic surgeon reviews other risks that can shorten the life of your new knee – such as infection, excessive weight gain or high impact sports.

The results of laboratory wear simulation testing have not been proven to predict actual joint durability and performance in people. A reduction in wear alone may not result in improved joint durability and performance because other factors can affect joint durability and performance and cause medical conditions that may result in the need for additional surgery. These other factors were not studied as part of the testing.

Important Safety Notes:

Knee replacement surgery is intended to relieve knee pain and improve knee functions. However, implants may not produce the same feel or function as your original knee. There are potential risks with knee replacement surgery such as loosening, fracture, dislocation, wear and infection that may result in the need for additional surgery. Longevity of implants depends on many factors, such as types of activities and weight.

Do not perform high impact activities such as running and jumping unless your surgeon tells you the bone has healed and these activities are acceptable. Early device failure, breakage or loosening may occur if you do not follow your surgeon’s limitations on activity level. Early failure can happen if you do not guard your knee joint from overloading due to activity level, failure to control body weight or accidents such as falls. Talk to your doctor to determine what treatment may be best for you.

1. G. Hunter and M. Long, “Abrasive wear of oxidized Zr-2.5Nb, CoCrMo, and Ti-6Al-4V against bone cement,” 6th World Biomaterials Cong. Trans., Society for Biomaterials,Minneapolis, MN, 2000, p. 835.

Oxinium™ - Oxidized Zirconium (knee)

What is OXINIUM™ Oxidized Zirconium?

If it is determined that an implant made with VERILAST™ technology is right for you, the femoral – or thighbone portion – of your implant will be made from OXINIUM Oxidized Zirconium – a patented and award winning ceramicised metal alloy that Smith & Nephew spent more than a decade developing.

During manufacture, OXINIUM implants undergo a process that transforms the implant’s surface into a hard, ceramicised metal – while still retaining all of the durability of the underlying metal. In addition to being more durable than a true ceramic, this metal implant’s ceramicised surface is more than twice as hard and therefore twice as resistant to the kind of scratching that can cause a cobalt chrome implant to wear out before its time.1

Important Safety Notes:

Knee replacement surgery is intended to relieve knee pain and improve knee functions. However, implants may not produce the same feel or function as your original knee. There are potential risks with knee replacement surgery such as loosening, fracture, dislocation, wear and infection that may result in the need for additional surgery. Longevity of implants depends on many factors, such as types of activities and weight.

Do not perform high impact activities such as running and jumping unless your surgeon tells you the bone has healed and these activities are acceptable. Early device failure, breakage or loosening may occur if you do not follow your surgeon’s limitations on activity level. Early failure can happen if you do not guard your knee joint from overloading due to activity level, failure to control body weight or accidents such as falls. Talk to your doctor to determine what treatment may be best for you.

1. Zardiackas, Lyle D., Kraay, Matthew J., Freese, Howard L, editors. Titanium, Niobium, Zirconium, and Tantalum for Medical and Surgical Applications ASTM special technical publication; 1471. Ann Arbor, MI: ASTM, Dec. 2005

What is XLPE?

What is XLPE or Highly Cross-Linked Plastic?

As remarkable as OXINIUM™ Oxidized Zirconium is, it is the combination of the OXINIUM material on XLPE that makes VERILAST™ Technology. XLPE is created by altering chemical bonds in the polyethylene we use to create our plastic inserts. By doing so, we are able to create a tighter weave at the molecular level, thus reducing the amount of wear experienced when the metal component rubs against it. Perhaps the easiest way to think of it is like a fabric with a higher thread count.

Important Safety Notes:

Knee replacement surgery is intended to relieve knee pain and improve knee functions. However, implants may not produce the same feel or function as your original knee. There are potential risks with knee replacement surgery such as loosening, fracture, dislocation, wear and infection that may result in the need for additional surgery. Longevity of implants depends on many factors, such as types of activities and weight.

Do not perform high impact activities such as running and jumping unless your surgeon tells you the bone has healed and these activities are acceptable. Early device failure, breakage or loosening may occur if you do not follow your surgeon’s limitations on activity level. Early failure can happen if you do not guard your knee joint from overloading due to activity level, failure to control body weight or accidents such as falls. Talk to your doctor to determine what treatment may be best for you.

Verilast Knee Technology

OXINIUM™ + XLPE VERILAST™ Technology

If knee replacement is in your future, you’ve come to the right place to learn about one of the truly significant advancements in joint replacement materials in the past 20 years, VERILAST Knee Technology.

It’s important to remember that not every knee implant is the same. VERILAST Knee Technology directly addresses one of the most commonly cited concerns associated with knee replacement implants, implant wear.

Whether or not to undergo knee replacement surgery is a very important decision. No matter how statistically safe and successful knee replacement surgery has proven to be, every surgery has risks. Before making any surgical decision, conversations should take place with your family, your primary care doctor and your orthopaedic surgeon to make sure that knee replacement with VERILAST Technology is the right course of action for your particular situation.

Important Testing Note:

VERILAST knee wear testing and results apply only to the VERILAST LEGION CR Primary Knee System only. Extended lab-testing for other VERILAST knee systems have not been performed. The results of laboratory wear simulation testing have not been proven to predict actual joint durability and performance in people. A reduction in wear alone may not result in improved joint durability and performance because other factors, such as bone structure, can affect joint durability and performance and cause medical conditions that may result in the need for additional surgery. These other factors were not studied as part of the testing.

Important Safety Notes:

Knee replacement surgery is intended to relieve knee pain and improve knee functions. However, implants may not produce the same feel or function as your original knee. There are potential risks with knee replacement surgery such as loosening, fracture, dislocation, wear and infection that may result in the need for additional surgery. Longevity of implants depends on many factors, such as types of activities and weight.

Do not perform high impact activities such as running and jumping unless your surgeon tells you the bone has healed and these activities are acceptable. Early device failure, breakage or loosening may occur if you do not follow your surgeon’s limitations on activity level. Early failure can happen if you do not guard your knee joint from overloading due to activity level, failure to control body weight or accidents such as falls. Talk to your doctor to determine what treatment may be best for you.

1. Goldsmith AA et al., “Comparative study of the activity of the total hip arthroplasty patients and normal subjects”. J Arthrop, (16)5:613-619, 2001.

2. Morbidity and mortality weekly report, 55(40):1089-1092, October 13, 2006.(Accessed on October 30, 2009).

3. Gioe TJ et al., “Knee Arthroplasty in the young patient – Survival in a community registry”. Clin Orthop Relat Res, 464:83-87, 2007.

4. Wallbridge N and Dowson D. “The walking activity of patients with artificial hip joints”. Eng Med 11:95, 1982

5. Wimmer M A et al., “Joint motion and daily activity profile of total knee patients in comparison with the ISO knee wear simulator”. Paper 0159, 48th ORS, 2002.

6. Huddleston J I et al., “How often do patients with high-flex total knee arthroplasty use high flexion?”,Clin Orthop Relat Res, 467:1898-1906, 2009.

7. Naal F D et al., “How active are patients undergoing total joint arthroplasty? A systematic review”, Clin Orthop Relat Res, DOI 10.1007/s11999-009-1135-9, published online: 28 October 2009.

All information provided on this website is for information purposes only. Every patient’s case is unique and each patient should follow his or her doctor’s specific instructions. Please discuss nutrition, medication and treatment options with your doctor to make sure you are getting the proper care for your particular situation. If you are seeking this information in an emergency situation, please call 911 and seek emergency help.

All materials copyright © 2016 Smith & Nephew, All Rights Reserved.