What Type Of Metal Is Used In Knee Replacements

Understanding The Materials Used In A Knee Replacement

We live in a wonderful time of impressive technological and medical advancements. We can treat many disorders, but unfortunately, we cannot treat aging. In other words, despite living longer, we fall prey to old age and its numerous ills. One of the most common issues that come with aging is getting a bad knee. Fortunately, there is a fix: knee replacement surgery. To learn about which of the materials used in a knee replacement surgery is best suited for you, check out this article!

Different Types Of Knee Replacement Implants

Oct 3, 2016 | Patient

*This post was co-authored by Grace McClure and Dr. Trevor North

This checklist of factors to finding the best implant may seem overwhelming, but luckily, this decision is usually left in the hands of your orthopedic surgeon. After all, surgeons have preferred implant manufacturers and only a couple different styles they work with. Very rarely do surgeons operate with multiple brands and more than a few styles. Your surgeon should be an expert in the exact type of implant you will receive.

With that said, lets get you acquainted with all things knee replacement implants, shall we? This way, you can assist your care team in matching you with an implant that best matches your lifestyle, activity level and other requirements.

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What Type Of Surgery Does Dr Chien

What methods will you receive with Dr Chien-Wen Liew

Dr Chien-Wen Liew has a dedicated practice in only total hip and total knee replacements. He no longer accepts new referrals for sports injury, trauma or other conditions of the hip and knee. This allows a dedicated focus to optimising all efforts towards a successful total hip replacemnt or total knee replacement.

total hip replacement

For over 8 years, all total hip replacements have been performed using the Direct Anterior Approach. This is an approach where no muscles or tendons are cut or detached during surgery. A cementless stem and socket combined with a ceramic on ceramic articulation will be used in most cases.

total knee replacement

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Younger Patients Needing Joint Replacement

As younger and more active patients are seeking and receiving joint replacements, the importance of developing new materials to combat wear also increases. At HSS, the age at which patients undergo knee replacement surgery is rapidly decreasing . This change in the demographics of patients seeking knee replacement is the primary motivation for improving implant materials.

Figure. 1. Patients undergoing total knee replacement surgery at HSS

How Can Metal Allergies Or Sensitivities Affect Joint Replacement

If a patient has a metal sensitivity or allergy, there is concern that using a metal joint replacement implant may cause a negative reaction that could lead to the need for a revision joint replacement or a compromised result.

Joint replacements are designed for low friction movement but they still shed tiny particles of metal with use. Tissue reactions to this implant wear debris can be a reason for joint revision surgery. However, patients with metal allergies or sensitivities may react more strongly to these metal particles. For these patients, the new joint becomes inflamed and painful, even though issues like infection, implant wear and loosening have been ruled out.

If a patient has a known metal allergy, Dr. Pritchett recommends metal-free implant options. If a patient is concerned about metal allergy or sensitivity, metal allergy tests can be done but most patients are best served by looking at alternative implant options.

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These Are The Features That Should Be Present In An Ideal Knee Implant

Allow for normal activity and motion

Last the expected 15-20 years or more.

Have a good track record of use in joint replacement recipients

Meet your conditions, needs, and any other requirements Your surgeon will ask for information regarding lifestyle, allergies, etc.

Be familiar with the brand and style of the selected surgeon.

High Flexion Total Knee System

Can I Avoid Or Postpone A Knee Replacement

The choice on whether to have surgery to address arthritis of the knee joint depends on multiple factors, including:

• the condition of the knee joint
• the patientâs age and activity level

In cases where the damage from arthritis is minimal, and/or if the patient does not have a very active lifestyle, nonsurgical treatments by be tried, including:

• physical therapy
• , such as ibuprofen
• weight loss to reduce pressure on the knee

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Types Of Knee Implants Used In A Knee Replacement Surgery:

A whole knee joint implant is primarily made up of 3 components. A femoral component that is attached to the resurfaced thigh bone, a tibial component that is affixed to the prepared shin bone, a plastic spacer that is placed between them and a patellofemoral component that replaces the natural knee cap.

The Materials: What Is A Knee Joint Made Of

Wait, what kind of metal is used in knee replacements?!

Artificial replacement parts can be made of strong plastic, metal, or ceramic. All knee replacements, partial or total, will have parts made of a few different materials . In most cases, each component is built from titanium, cobalt-chromium alloys, or a titanium and cobalt mixed metal. The chosen materials must be durable, allow for some flexibility with movement and be biocompatible .

Cobalt-Chromium Alloys Chromium alloys are one of the most commonly used materials in implant components. This metal is biocompatible, tough, durable and will not be broken down inside the body. This material is commonly used for the femoral implant since it is very sturdy and the femoral implant has a lot of traction against the plastic spacer during movement. For those with nickel allergies, some particles from this metal can get into the bloodstream and cause a reaction. Please let your surgeon know if you have an allergy as there are alternatives.

Polyethylene This is a type of strong plastic found in the the tibial patellar component and the plastic spacer. The plastic components allow the metal pieces to glide smoothly throughout movement. This material is metal-free.

For Those with Nickel Allergies

Implant manufacturers, BioMet and Smith & Nephew, both make nickle-free versions of the femoral part.

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How Are Joint Implants Tested

Determining whether new types of implant bearing surfaces effectively reduce wear versus the conventional metal-on-polyethylene bearings is not as easy as it may seem. We are limited in our ability to study wear in the laboratory by our inability to simulate the lubrication conditions, the loads and the motions that occur over a broad range of daily activities by our patients.

Joint simulators are currently the best tools for studying wear because they provide an effective means of screening whether or not one combination of bearing surfaces is better than another. No acceptable animal models exist, and computer analyses of implant wear have only been proven to be effective for simpler constructs, such as ball-in-socket implants for the hip.

Complicating the problem further is that wear mechanisms differ depending on the joint. For this reason, data collected on a hip simulator may have little relevance for wear in a knee, elbow or shoulder replacement. Furthermore, the question is not just one of reducing the amount of wear, but also of the ways in which the size, shape and surface chemistry of released wear particles differ among various bearing surface combinations. These factors may ultimately influence the biological reaction and subsequent tendency for osteolysis.

What Can I Expect At Hss

Hospital for Special Surgery has been at the forefront of modern knee replacement since the operation was first introduced in the late 1960s. We have led the field ever since in a number of ways:

• : HSS has been ranked the No. 1 hospital for orthopedics by U.S. News & World Report for 11 years straight.
• Along with high rankings in patient satisfaction, HSS performs the most knee replacements with the lowest reported infection rates in the United States.
• Research and advancement: Smaller incisions, new implant materials and design, and sophisticated instrumentation have been â and continue to be â the areas of expertise of the hip and knee replacement surgeons of the HSS .
• HSS routinely uses the latest surgical techniques and technology, such as robotic-assisted and computer-assisted surgery.
• : Isolating the anesthesia to a particular body area helps avoid the potential problems that may accompany a general anesthetic. These techniques have been developed and refined by the HSS . Learn more about

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Joint Replacement For Metal Sensitive Patients

Patients who have metal allergies or sensitivities may have concerns about the implants used for joint replacement, which are typically made of titanium or cobalt chromium metal alloys. Fortunately, Dr. Pritchett has options for these patients that can help with metal sensitivity issues and may also provide superior wear characteristics over traditional metal implants.

Dr. Pritchett has practiced in the Seattle area for over 30 years. He is heavily involved in research to continue to improve upon joint replacement implants and techniques. His ultimate goal is to help patients suffering from joint pain and arthritis return to their normal activities, and to contribute to advances in technology, techniques, and implants that can improve upon long-term results for patients.

Failed Joint Replacement Components Cause Cancer

November 3, 2016: Seven substances added to 14th Report on Carcinogens

• Cobalt and cobalt compounds that release cobalt ions* in the body are being listed as reasonably anticipated to be a human carcinogen.
• Cobalt is a naturally occurring element used to make metal alloys and other metal compounds, such as military and industrial equipment, and rechargeable batteries. The highest exposure occurs in the workplace and from failed surgical implants.

*It does not include vitamin B-12, because cobalt in this essential nutrient is bound to protein and does not release cobalt ions.

Contact our team to discuss your case.

1 Laitinen M, Nieminen J, Reito A, et al. High blood metal ion levels in 19 of 22 patients with metal-on-metal hinge knee replacements. Acta Orthop. 2017 Jan 26:1-6. doi: 10.1080/17453674.2017.1283846.

2 Guenther D, Thomas P, Kendoff D, Omar M, Gehrke T, Haasper C. Allergic reactions in arthroplasty: myth or serious problem? Int Orthop. 2016 Feb 40:239-44. doi: 10.1007/s00264-015-3001-6. Epub 2015 Nov 2.

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How Long Is It Before I Can Walk After A Knee Replacement

Most patients progress to a straight cane, walker or crutches within two or three days after surgery. As the days progress, the distance and frequency of walking will increase.

Patients are usually able to drive a car within three to six weeks after surgery and resume all other normal activities by or before six weeks. Complete recuperation and return to full strength and mobility may take up to four months. However, in many cases, patients are significantly more mobile one month after surgery than they were before they had their knee replacement

Ial Knee Replacement Overview

A is also known as unicompartmental knee arthroplasty or unicondylar knee arthroplasty. In this surgery, damaged cartilage and bone are removed and replaced only in one diseased compartment of the knee. This differs from a total knee replacement, in which bone and cartilage from the entire joint are replaced.

Partial knee replacement is suitable for people who experience arthritis only in one compartment of the knee joint, rather than throughout the joint. It can also provide relief from pain and stiffness in some people who have medical conditions that make them poor candidates for total knee replacement surgery.

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What About A Custom Knee Replacement Made Just For My Leg

One of the most exciting innovations when I was practicing is the concept of custom-manufacture of knee implants that are made specifically to each patients size and unique anatomy. CT or MRI imaging is used to determine the precise anatomy of the patients ankle, hip, and knee. These data are sent to a company called CONFORMIS , where the metal and plastic pieces are custom-made for the patient in about 5-6 weeks, much like a tailor-made suit. The instruments used to implant the knee prosthesis are designed for a one-time use, specific to the patient, and are made of a biodegradable material. One neat package contains everything needed for the operation, and is unique for each knee joint, fitting only that one.

We used this in my practice beginning in 2013 and found it truly innovative, a meaningful step forward in knee replacement surgery. Our results showed earlier and easier recovery for the patient, and x-rays that are beautifully precise in terms of rotation, alignment, and sizing. This technology incorporates all of our knowledge and design understanding in knee replacement, worldwide. It increases patient safety, promotes quality and consistency, ensures precision and a perfect fit every time, and therefore has our full support.

Joint Replacement Options For Metal

Dr. Pritchett has been heavily involved in the research of joint replacement implants and techniques over his 30-year career in orthopedic surgery. Dr. Pritchett has used ceramic-coated hip, knee, and shoulder replacement implants in his practice for over 25 years, and has seen great results. While ceramic-coated implants are a great option for patients with metal allergies, they can offer benefits to all patients with their superior wear characteristics.

If you would like to schedule a consultation with Dr. Pritchett, please call our office at or use our Appointment Request form.

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Differences Between Total And Partial Knee Replacement

Knee replacement surgery is recommended when conservative treatments like physical therapy, braces, steroid injections and anti-inflammatory medication fail to alleviate pain.

If a patient requires surgery on both knees, its called a bilateral knee replacement. The two procedures can be done simultaneously or doctors may choose to use a staged bilateral approach that schedules the second surgery several days, weeks or months later.

The decision to have a total versus a partial knee replacement is based on a doctors recommendation after a full patient evaluation is performed.

What Are The Best Materials For Joint Replacement

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Are you considering a joint replacement surgery? What are the best materials for the surfaces that contact one another? These are called the bearing surfaces. Lets look at the benefits of different materials to understand the proposed procedure. Knowing your options can make you feel less anxious about the surgery and what to expect for the life of your implant. The materials used in the implant typically depend upon various factors, including:

• Patient age
• Surgeon preference
• Particular deformities/abnormalities of the hip or knee

Not all implants are options for every patient. Here is a brief description of some of the most commonly used implants:

Ceramic on Plastic – This type of implant uses metal parts that fit within the bone, but the bearing surface for the ball or head is made of ceramic material. The socket bearing or the cup is made of a special plastic called polyethylene. Ceramic head implants are designed to be the most resistant to wear. Early designs had the risk of breaking. The newer designs are much stronger and it is almost unheard of to have the newer ceramic femoral heads break. Ceramic heads are very hard and very smooth. As a result, they cause less wearing of the polyethylene. People who are sensitive to the nickel used in metal implants might be a good fit for the ceramic type. We use ceramic on polyethylene in the majority of total hip replacements.

Amir Jamali, MD

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What Joint Replacement Options Are Available For Patients With Metal Allergies

Dr. Pritchett offers ceramic-coated implants for hip replacement and resurfacing, knee replacement, and shoulder resurfacing. The implants are made of titanium metal for strength, and the ceramic coating covers the portions of the implant that are exposed to the soft tissues in the body and the bearing surfaces where movement occurs. The ceramic coating is expertly applied to a carefully prepared and polished surface. Fully ceramic implants can fracture but ceramic coated implants will not, so they are the safest and best material to use. The implants themselves are identical to normal hip, knee and shoulder implants, except that they have a ceramic coating. The polyethylene spacer is still used between the joint components–Dr. Pritchett does not recommend ceramic-on-ceramic joint replacements. Dr. Pritchett has used ceramic-coated implants in his practice for over 25 years with great success. These ceramic-coated implants have also been used in numerous studies that Dr. Pritchett has conducted over the years.

If a patient has a metal allergy or is concerned about potential issues with metal implants, Dr. Pritchett recommends ceramic-coated implants. For shoulder resurfacing procedures in particular, the ceramic-coated implants perform quite well because they articulate directly with the shoulder socket. For this reason, Dr. Pritchett frequently uses ceramic-coated implants for shoulder resurfacing even if metal allergies are not a concern.

What Companies Make Artificial Knees

Zimmer persona knee by Zimmer Biomed

Zimmer world headquarters are in Warsaw, Indiana & was founded in 1927.

Listed Advantages:

• Comprehensive sizing with tighter increments

• Side-specific kinematics

• 5 successful years in clinical use

Evolutis was created in 1999 by a group of experienced orthopedic professionals.

Listed Advantages

• Femoral Condyles and tibial baseplates are made of Cobalt-Chromium

• Reversible femoral Condyles right and left are available in 6 sizes for cemented use only

• A/P and M/L dimensions, and femoral resections identical to those of the Anatomic version

• Accentuated and highly congruent trochlear groove identical to Anatomic version

• Reversible tibial baseplate right and left available in 6 sizes, including the 3 smaller sizes with short keel

• Center of rotation of tibial insert in the middle of the M/L dimension

• The available tibial inserts, available in 5 thicknesses are made of polyethylene PEXEL moderately crosslinked and vacuum-packed.

• The instrumentation set limited to 3 trays

Vanquish Ligamentoplasty by Evolutis

VANQUISH system is meant to facilitate both ACL and PCL plastics through Kenneth-Jones or semitendinous-gracilis autograft techniques. The system is based on a unique and complete instrument set which includes a graft tensioning table, ACL and PCL guides, and strippers among others.

The VANQUISH implants can be combined with one another so as to adapt to the dedicated technique of the surgeon: interference screws, endo-button, and staples.

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