Total Knee Prosthesis

Reviewed by Greg Jaroszynski MD, FRCSC | Last updated May 2026

A total knee prosthesis replaces the worn surfaces of the knee with metal and highly durable plastic components designed to create a smoother, lower-friction joint.

Key Points

A total knee replacement resurfaces the arthritic parts of the knee rather than replacing the entire bone.
The femoral component is metal.
The tibial side usually includes a metal tray and a highly durable polyethylene plastic insert.
The kneecap may be resurfaced with a plastic button when appropriate.
The components may be fixed to bone with cement or with modern uncemented fixation.

Components

The goal of total knee replacement is to remove the worn surfaces of the arthritic joint and replace them with new artificial surfaces.

The femoral component covers the end of the thigh bone and is made of a metal alloy. The tibial component replaces the top surface of the shin bone with a metal tray that supports a highly durable polyethylene plastic insert. Together, these surfaces allow the knee to bend and straighten with less pain and friction.

The Kneecap

The patella, or kneecap, is often resurfaced with a plastic button. Some surgeons choose not to replace the patellar surface in selected cases. The decision depends on the condition of the kneecap cartilage, the shape of the joint, the implant system, and the surgeon's practice.

In my practice, I usually resurface the kneecap.

Cemented Fixation

Cemented fixation has been the traditional standard for many years and has excellent long-term registry results. In a cemented knee replacement, the implant is held to the bone by a thin layer of bone cement that hardens during the operation.

Cemented fixation remains a very good option, especially when bone quality, anatomy, deformity, or surgical circumstances make it the most reliable choice.

Uncemented Fixation

Modern uncemented knee implants use a tight press-fit and a porous surface designed for bone to grow onto or into the implant. The goal is biological fixation.

Earlier generations of uncemented knees had mixed results, but modern porous designs and manufacturing techniques have improved. Recent randomized-trial meta-analyses generally show similar revision rates, aseptic loosening rates, infection rates, and function between cemented and uncemented total knee replacement in appropriately selected patients. Registry data still need ongoing long-term follow-up for newer designs.

Choosing the Implant

The choice between cemented and uncemented fixation is individualized. Bone quality, age, activity level, body size, deformity, implant design, and intraoperative stability all matter.

I am increasingly using modern uncemented total knee designs in appropriate patients, while still using cemented fixation when it is the better choice for the patient's bone, anatomy, or surgical situation.