Different Types of Knee Replacement Prosthesis – Which One is Right for You?

Knee replacement prostheses can be classified in different ways. We will discuss over here one way in an easily understandable manner. However, if you still doubt the choice of prosthesis please talk to your doctor before surgery.

A knee replacement prosthesis is commonly made up of four main parts: the femoral component, the tibial component, the patella component, and the insert or spacer (a component that stays in between the femur and tibia component).

Knee replacement prostheses can be divided into cemented and uncemented prostheses, which means bone cement is used during surgery. The majority of the prosthesis used worldwide is cemented prosthesis.

Disclaimer – The author did not receive financial support from any company that manufactures implants for joint replacement surgery.

1) Total knee replacement

Total Knee Replacement implant

A total knee replacement involves removing all parts of your knee joint except for a small portion at either end.

The damaged cartilage and bone are then replaced with an artificial joint. Artificial knee implants have evolved greatly in recent years and many patients who have undergone a total knee replacement report significant improvement in their mobility, as well as relief from pain and discomfort.

2) Partial knee replacement or Unicompartmental knee arthroplasty (UKA)

Unicondylar knee replacement prosthesis

Partial knee replacement (also called unicompartmental knee replacement) replaces part of your knee joint without removing all of your natural joint surfaces.

Only part of your thighbone (femur) and leg bone (tibia) is replaced during partial knee replacement. Some patients with early arthritis in their knees may benefit from partial knee replacement if only one out of three compartments are involved.

For most people, you can expect to go home from surgery within 24 hours and be back to work in about 4 weeks.

Unicompartmental knees are primarily recommended for younger people who want to maintain their active lifestyles as well as older people who are in poor health overall and cannot withstand a longer recovery period.

3) Patellofemoral replacement

Patellofemoral replacement implant

This type is replacement is least commonly used. If you have only patellofemoral compartment arthritis, you might get benefit from patellofemoral replacement. A common problem encountered by patients with patellofemoral arthritis is pain over the knee cap during knee bending.

The surface of the patella facing the femur and the adjacent part of the patella are replaced with prostheses.

Replacement prosthesis companies

The way to choose a replacement prosthesis is to look at the records of various collaborative registries around the world. Commonly used knee replacement companies are DePuy Synthes (Johnson & Johnson), Zimmer Biomet, Smith & Nephew, and Stryker. Replacement prostheses manufactured by these companies have shown good clinical performance. The products of these companies are imported into India. One of the Indian manufacturers worth mentioning is Max Healthcare. This list is not exhaustive and does not suggest which one to use.

Physician understanding, familiarity, and comfort with the use of certain company implants are important for achieving better results than the patient's choice.

Other ways to classify knee replacement prosthesis

CR (Cruciate retaining) or PS (Posterior stabilized)

Cruciate retaining (left) and posterior stabilized (right) implant

When PCL (Posterior cruciate ligament) of the knee is retained during replacement surgery, your doctor will place a CR implant. Otherwise, if PCL needs to be removed, the doctor will fix a PS implant. Survivorship of both the implants is the same.

Fixed bearing or Rotating platform

Fixed bearing knee implant

As we know from our earlier discussion a component of knee replacement called an insert, which is made up of medical grade plastic, is placed in between the femur and tibia component. Fixed bearing insert is fixed with tibia component, whereas Rotating platform insert, as the name suggests, can rotate free and not fixed with tibia or femur.

Rotating platform or Mobile bearing knee

Which one is right for me?

Choosing the right prosthesis depends on many factors. Preoperative knee condition, patient functional requirements, bone quality, etc. are the most important factors in implant selection. Affordability is another factor that can limit your options. Implants are often selected during surgery after opening a joint.

There are many other ways to classify total knee arthroplasty, but that is a complex debate and beyond the scope of this article.

Finally, the author wants to reiterate that it is best to leave the choice of the prosthesis to the surgeon.

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