For those that enjoy an active lifestyle, keeping knees healthy is extremely important. As the knees provide support for the rest of the human body, mobility can be greatly reduced if they’re damaged. In the event of injury and knee pain, some people choose to undergo knee replacement to solve the problem. With that in mind, join us as we examine the subject of artificial knees and ask: what is the best knee replacement material?
What is an artificial knee joint?
Sometimes referred to as a total knee replacement, an artificial joint is a structure designed to replace an original knee joint. It is usually made of different types of metal and plastic that aim to recreate the same level of mobility experienced with an undamaged knee.
The makeup of the joint is generally quite straightforward. Metal caps replace both the thigh bone and shin bone, while high-density plastic is used to replace damaged cartilage. Both the tibial component and the femoral component are made of metal. Bone cement (Polymethyl methacrylate) is traditionally used to help the implant remain in place.
Are all knee replacements the same?
In a word: no. Over time, advances in the technology, materials and the design of knee implants have seen changes in the types of materials used. Nowadays, the majority of artificial knee joints feature the same materials but have subtle differences in their design. These differences are tailored to the specific needs and activity levels of the patient. Some surgeons now use different materials depending on the needs of the patient. Your doctor or consultant will be able to identify which materials are best suited to meet your specific needs.
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Types of knee replacement materials
Before you consider the different types of materials used, it’s important to recognise the signs you need a knee replacement. Once you’ve been given a diagnosis, the important work can begin around research. The main type of material used in knee replacement implants are:
- Metal-on-plastic – The most common type of implant features a metal femoral component that rides on a polyethylene plastic spacer attached to the tibial component. The metal components are most commonly made from cobalt-chromium or titanium. Some are coated in zirconium in the event the patient has a pre-existing metal allergy. This combination boasts a long life span. Whereas advances in technology have reduced the risk, one of the disadvantages of this combination involves the potential for an immune reaction. This is caused by particles wearing away from the plastic spacer.
Metal implants
The vast majority of metal implants are made of titanium or cobalt-chromium. While the materials used in the implant are important, the emphasis is actually on its design. This allows for the artificial structure to be tailored to the specific needs of the patient.
Plastic implants
Of all the available plastic parts involved in total knee replacement, Polyethylene plastic is the most important. While Polyethylene was one of the most common causes of knee revision surgery, technological advances over the past three decades have meant the risks associated with the plastic wearing out have greatly reduced. Please note that implants made entirely from plastic are not available at Practice Plus Group.
Ceramic implants
Ceramic implants can be used to make up the entire artificial joint, or as the surface of the femoral component. One major advantage of ceramic implants is that they’re scratch-resistant. This means they’re much less likely to wear down over time and have a long life expectancy. The downside of ceramic implants is their cost and susceptibility to shattering. Please note that implants made entirely from ceramic are not available at Practice Plus Group.
Cobalt chrome v titanium knee replacement
It should be noted that any metal work that’s implanted into the body has to be biocompatible. However, it’s not entirely unheard of that patients with pre-existing allergies to metal can suffer reactions. Cobalt chrome is a hard-wearing material whilst titanium is softer and a little more flexible, with properties similar to that of bone. These two metals are often used in combination to great success to make knee implants.
Types of implants available at Practice Plus Group
At Practice Plus Group, all knee implants are generally made with a metal femur and tibia. The spacer that sits in between these components is made from plastic. Zirconium-coated implants can be provided if the patient suffers from pre-existing allergies to metal.
What is the most common knee replacement used?
The metal-on-plastic combination is the most commonly used material for knee implants. A closer look reveals that cobalt-chromium is the most frequently used metal. This is because it’s biocompatible and is very durable. In terms of plastics used, Polyethylene is preferred over other options. While the materials used in the implant are important, the emphasis is actually on its design. This allows for the artificial structure to be tailored to the specific needs of the patient.
Factors to consider when choosing the best joint replacement for you
Before settling on a specific type of implant for your knee replacement, you’ll have a lot to consider. Your age and day-to-day activity levels will need to be taken into account, as well as undertaking some research about the do’s and don’ts after knee replacement surgery. You’ll also need to factor in any known metal allergies as the implants are likely to contain metal.
Other factors to consider are the private operation costs you’re willing to pay, the best time of year to have knee replacement, and the longevity of the implant, i.e. how long you want the implant to last. Any abnormalities should be highlighted to your doctor before proceeding with surgery.
At Practice Plus Group, we use the Orthopaedic Data Evaluation Panel (ODEP) to ensure our implants are of the highest quality. Data from knee and hip replacements is collected, analysed and given a star rating. The number of stars denotes the years worth of data, which is why we don’t use any materials with less than a 10 star rating. This is to ensure the materials we use have a history of successful outcomes for our patients.
What is the longest-lasting knee replacement?
Longevity is one of the most important factors to consider if you need a knee replacement. The implant itself can be made from a range of different materials, which in turn can be combined to great effect. Each material has pros and cons, and some are more likely to last longer than others. The majority of knee replacements last between 10-15 years, with occasional cases lasting for much longer.
How long does a titanium knee replacement last?
Implants are a combination of metal and plastic with variations on the structure’s design that are tailored to the needs of the patient. Each implant is expected to last between 10-15 years with some lasting beyond 20.
How long does a ceramic knee replacement last?
Ceramic knee implants aren’t available at Practice Plus Group. Instead, implants are a combination of metal and plastic. They vary from patient-to-patient, and the structure’s design is tailored to their needs. Each implant is expected to last between 10-15 years with some lasting beyond that timescale.
How long does a plastic knee replacement last?
Implants made entirely of plastic aren’t widely available and aren’t available at Practice Plus Group. Instead, implants are a combination of metal and plastic. They vary from patient-to-patient, and the structure’s design is tailored to their needs. Each implant is expected to last between 10-15 years with some lasting beyond that timescale.
Knee replacement material costs
While it’s difficult to pinpoint the exact costs of the different knee replacement materials, it is possible to compare them.
Titanium knee replacement cost
From the metal options available, titanium is more expensive than cobalt-chromium. However, the two are often used in combination to great success.
Ceramic knee replacement cost
Ceramic implants are not widely available and aren’t available at Practice Plus Group. However, Zirconium-coated implants are more expensive to make and tend to be used for patients who have an allergy to metal. However, they have the benefit of being both the longest-lasting and completely scratch resistant.
Plastic knee replacement cost
While you cannot choose to have an artificial implant made solely of plastic, the plastic parts can be combined with ceramic or metal. Metal-on-plastic implants are the most common combination of the available options.
Which implants are best for knee replacement?
We explored the different options, so it’s time to answer the question: what’s the best material for knee replacement implants? It may sound like we’re dodging the question, but the answer entirely depends on you. If you need total knee replacement surgery, you need to think about your age, how much you’re willing to pay, and how long you want your implant to last. You’ll also need to listen to the recommendations of your consultant. They will be able to advise as to the best course of action.
Acknowledgements
This article was completed with the help of Mr Nurul Ahad, Medical Director and Orthopaedic Surgeon at Practice Plus Group. Mr Ahad graduated from Barts and the London School of Medicine before being appointed Trauma Consultant at Barking Havering and Redbridge University Hospitals in 2010. His expertise has led to several publications and international presentations.
With over 15 years of experience in orthopaedic surgery, he has a proven track record of delivering an excellent quality of service.
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