What Are the Parts of a Total Hip Implant?

A total hip implant usually has four main parts: an acetabular cup or shell, a liner, a femoral stem, and a femoral head. These hip implant components replace damaged joint surfaces and work together to support movement.

Each part has a separate job , which helps explain why your surgeon discusses several pieces rather than one device. Designs, materials, and attachment methods vary according to your anatomy and bone health.

Start with where each piece sits and what it does.

The Four Main Hip Implant Components

Acetabular Cup or Shell: The Socket Foundation

The acetabulum is your natural hip socket, located in the pelvis. During total hip replacement, the surgeon prepares this socket and places an artificial cup into it.

In many designs, the cup includes an outer shell that holds a separate liner. The shell provides support on the pelvic side of the replacement. Its position affects how the ball moves within the socket, so secure placement and alignment matter for stability.

Liner: The Inner Moving Surface

The liner fits inside the socket shell. Its smooth inner surface receives the artificial ball and allows it to move as you walk, sit, or bend.

Together, the liner and ball form the bearing surface , where the two moving parts meet. This pairing affects friction and wear over time. The liner also contributes to stability, so its design must work with the head and the rest of the implant system.

Femoral Stem: Support Inside the Thighbone

The femur is your thighbone. The femoral stem extends into the hollow central space of its upper portion after the surgeon removes the damaged natural ball.

The stem supports the new ball and transfers forces into the thighbone when you stand or walk. Its fit depends on the shape and strength of your bone. Depending on the surgical plan, the surgeon secures it with bone cement or a cementless fixation method.

Femoral Head: The Replacement Ball

The femoral head is the rounded ball attached to the upper end of the stem. It replaces the natural ball at the top of your thighbone.

This head moves within the liner to recreate the hip's ball-and-socket motion. It may be ceramic or metal, often cobalt-chromium alloy. Its dimensions and connection to the stem help your surgeon adjust the reconstructed hip's mechanics, including leg length and the tension of surrounding soft tissues.

How Implant Materials and Designs Vary

A description such as "ceramic hip" usually refers to one component or the bearing combination. It doesn't mean every part uses the same material. Our explanation of hip replacement implant materials covers these differences.

Designs also vary. For example, a dual mobility implant adds movement between a mobile liner and the socket, which may help selected patients with increased dislocation risk.

However, a specialized design isn't automatically better for everyone. Your surgeon considers stability, bone support, and how the components work together. Material choice alone cannot compensate for poor positioning or inadequate fixation.

Cemented vs Cementless Fixation

Fixation means how an implant attaches to your bone. The cup and stem need secure support, but they don't always use the same attachment method.

Cemented Fixation

With cemented fixation, the surgeon places bone cement between the implant and surrounding bone. The cement hardens during surgery and provides immediate fixation.

Surgeons may consider a cemented stem when the thighbone is thin or fragile. However, age alone doesn't determine the choice. Bone quality, bone shape, and the overall reconstruction also matter.

Cementless Fixation

A cementless implant initially relies on a snug press-fit within prepared bone. Its surface then allows bone to grow onto or into it, creating longer-term attachment.

That initial grip matters while bone growth develops. Cementless fixation can work well when the bone provides adequate support.

A hybrid replacement may combine a cemented stem with a cementless cup. Neither method suits everyone; cemented versus cementless fixation depends on your individual bone and surgical needs.

How Surgeons Match the Components to Your Hip

Component selection involves more than choosing a ball or stem in isolation. Your surgeon plans socket position, stem fit, leg length, and joint stability together.

Imaging helps establish an initial plan. During surgery, temporary trial components allow the surgeon to assess movement and adjust the reconstruction before placing the final parts.

Our guide to hip implant component sizing describes this process. When you meet with us, ask how your bone quality and anatomy affect the proposed combination.

Key Takeaways

• The cup and liner form the replacement socket, while the stem supports the replacement ball.
• The head and liner move against each other, so their pairing affects wear and motion.
• Fixation, component position, and fit matter alongside material choice.

Frequently Asked Questions

Is SuperPATH a Type of Hip Implant?

SuperPATH is a surgical approach, meaning a way to access the joint. It isn't a specific implant material or component system. The implant still needs a suitable design, accurate positioning, and stable attachment to bone.

Does Revision Surgery Replace Every Component?

Not always. In some cases, the surgeon can replace a head or liner while retaining securely fixed components. Other problems require replacement of the cup, stem, or both, depending on the cause and extent of damage.

Understanding Your Hip Replacement Plan

The four main parts perform different tasks, but they function as one connected system. A suitable replacement balances smooth movement with stable support in your bone.

Understanding each component makes the surgical discussion easier to follow. The recommendation should reflect your anatomy, bone health, and movement needs rather than a single material or design label.