Total Knee Replacement Surgery

Preparing for Surgery: How Do Artificial Knee Implants Work?

By getting answers to your questions and learning what to expect before, during, and after your surgery, you can help ensure a smooth and successful recovery. Replacing your natural knee with an artificial one requires trust and an understanding of how the implant will help you achieve the activity level you want. Watch this video to see how knee implants are made and mimic the behavior of the human knee.  View Transcript

How do Artificial Knee Implants Work?

Stephen White, General Manager and Vice President – Knee Division, Zimmer Holdings, Inc:

“Knee replacement designs have evolved a lot in the last twenty to thirty years.  We've seen an improvement in materials.  We've seen an improvement in the quality of product that we're manufacturing, but we're not done yet.  I think what we'll see, going forward in the next ten years, is really a focus on personalizing those implant designs and personalizing the way we deliver the implant into each patient.” 

Voice of:  Stephen White

Early knee replacements used a hinge, which enabled basic movement but did not closely simulate the way an actual knee moves.  Remarkably improved over several decades, today's sophisticated prostheses provide joint mobility that allows recipients to enjoy activities such as walking and swimming.  We test our product over millions of cycles to ensure the implant isn't going to wear out.  From an engineering perspective, we like to consider that a million cycles of testing will equal one year's worth of use. 

Stephen White:

“Other test that we will do will be biocompatibility tests.  We'll make sure that the particles and the prosthesis aren't going to have an adverse reaction in the body and then we will also do extensive testing on individual components and make sure those components are robust and biocompatible. 

Primary total knee replacement can be broken out into, really two categories, a fixed bearing design, in which the tibial insert is fixed to the tibial baseplate or a mobile bearing design, in which that tibial surface is free to float and rotate on that tibial baseplate." 

Voice of:  Stephen White

A surgeon attaches a tibial component with polyethylene to the metal beneath it.  A femoral component rolls along the cushioned surface.  Mobile bearing devices also use the three primary components, but they allow the polyethylene insert to rotate slightly within the metal tibial tray.

Stephen White:

“When we talk about the differences between different implant designs, one of the considerations is also the mechanism that we use to fix the implant to the bone surface.  Here we have an example of a cemented implant.  The surgeon will cement this surface to the bone using what we call bone cement.  Bone cement is an acrylic cement that is designed specifically to be used in the body and it's very biocompatible.  The surgeon will apply the cement to the undersurface of the base and along the stem component.  If your surgeon chooses to use a cementless or a cement-free device, what you should expect is a design that will sit flush to the bone surface.  Over time bone will incorporate into these pores and that will provide the long-term fixation of this implant in your knee replacement.” 

Voice of:  Stephen White

Once implanted in the body, either of these types of systems, will provide greater flexion and range on how far you can bend or flex your knee.  Today's artificial knees closely mimic the natural motion of a knee and are allowing many people to lead healthy, active lives without pain.  Eighty percent of knee replacements last twenty years, letting recipients swim, walk, bicycle and play tennis as they age. 

Stephen White:

“You will find that there are a lot of choices out there for total knee replacements and I think the thing that you have to convince yourself is:  first, that you're confident with your surgeon and their experience with the prosthesis that they choose and secondly, you want to make sure that you've communicated to the surgeon what types of activities you want to get back to doing.  Going through that process and being open and communicating with your surgeon will only provide you with a better outcome after the procedure.”

Understanding Costs

All surgeries are costly, and knee replacement—from inpatient charges to the cost of missing work—is no exception.

Risks and Complications

Knee replacement surgery has an extremely high success rate. However, as with any surgery, there are potential complications.

Choosing a Surgeon

You should have complete confidence in the surgeon who will perform your knee replacement.

Preparing for a Knee Replacement

Before Surgery: Everything You Need to Know

Planning for the surgery can feel overwhelming. Take it one step at a time and use this guide to help prepare for a knee replacement.

Types of Implants

There are different implant manufacturers, types, and features for you and your surgeon to discuss and consider.

Implants for Women

Recently, manufacturers have begun to market knee implants designed specifically for a woman's body.

TKR Surgery Step-by-Step

This step-by-step guide will give you a sense of exactly what will happen to your body during a knee replacement procedure.

Questions to Ask During Preoperative Planning

The preoperative evaluation is an important step in the total knee replacement process. You should have all your concerns addressed before the operation.

Muscle Strengthening Before Surgery

You can improve your chances for a speedy recovery by strengthening your knee and improving flexibility prior to surgery.


You will be prescribed various preventative and pain management medications before and after the surgery.

After Surgery

It's essential to make your post-surgery plans as early as possible—recovery and rehab will greatly impact the final outcome of your procedure.

Prepare Your Home for Your Recovery

After surgery, you will be spending most of your time at home rehabbing. It's important to prepare your living environment to facilitate a more comfortable experience.


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