What Is a Total Hip Replacement?
Plain-English answers to the questions everyone has — but not everyone asks.
Total hip replacement — also called total hip arthroplasty, or THR — is one of the most commonly performed and most successful orthopedic surgeries in the world. Hundreds of thousands of people have it every year. And yet most people facing it feel like they're the only one who doesn't know what's actually going to happen.
This page explains the basics: what the surgery involves, what gets replaced, what the different approaches are, and what the implant is made of. No jargon. No scare tactics. Just information.
The Hip Joint: A Quick Anatomy Lesson
The hip is a ball-and-socket joint. The ball (femoral head) sits at the top of the thigh bone (femur) and fits into a cup-shaped socket (acetabulum) in the pelvis. Smooth cartilage covers both surfaces, allowing the joint to move with minimal friction. When that cartilage breaks down — from arthritis, injury, or other conditions — the result is bone rubbing on bone, which causes pain, stiffness, and loss of function.
What Gets Replaced
Femoral stem
A metal stem inserted into the hollow center of the femur (thigh bone) to anchor the implant.
Femoral head (ball)
A ball — usually ceramic or metal — that attaches to the top of the femoral stem and replaces the natural femoral head.
Acetabular cup
A cup-shaped component that replaces the natural hip socket. It is typically made of metal and lined with a smooth material.
Liner
A liner inside the acetabular cup provides the bearing surface against the femoral head. Liner material varies by implant type.
Surgical Approaches
There are several ways a surgeon can access the hip joint to perform a replacement. The approach refers to the direction from which the surgeon enters — and each has different implications for the muscles and tissues involved. No single approach is universally superior. The right approach depends on the patient's anatomy, the surgeon's training and experience, and other clinical factors.
Anterior approach
The surgeon accesses the hip from the front, working between muscles rather than cutting through them. This approach has gained popularity in recent years. Some surgeons and patients report faster early recovery, though long-term outcomes are generally comparable to other approaches. It requires specialized training and equipment.
Posterior approach
The most commonly used approach worldwide. The surgeon accesses the hip from the back. It provides excellent visibility of the joint. Historically associated with hip precautions (movement restrictions) in the early recovery period, though many surgeons have moved away from strict precautions with modern techniques.
Lateral and anterolateral approaches
The surgeon accesses the hip from the side. These approaches are less common than anterior and posterior but are used by many experienced surgeons with excellent results.
The best approach is the one your surgeon performs most skillfully and that is appropriate for your anatomy. Ask your surgeon which approach they use and why.
Implant Materials
The bearing surfaces — the parts of the implant that move against each other — come in several material combinations. Each has different properties in terms of wear, durability, and clinical history.
Ceramic-on-polyethylene
A ceramic femoral head against a highly cross-linked polyethylene liner. One of the most commonly used combinations today, with a strong long-term track record.
Ceramic-on-ceramic
Both the ball and liner are ceramic. Very low wear rates. Used in some younger, more active patients. Rare squeaking has been reported in some cases.
Metal-on-polyethylene
A metal femoral head against a polyethylene liner. A long-established combination with a good track record.
Metal-on-metal (historical note)
Metal-on-metal implants were widely used in the 2000s but fell out of favor after reports of elevated metal ion levels and adverse tissue reactions in some patients. Most surgeons no longer use metal-on-metal bearings for primary hip replacement. If you have a metal-on-metal implant, discuss follow-up monitoring with your surgeon.
Robotic-Assisted Hip Replacement
Robotic-assisted hip replacement uses computer-guided technology to help the surgeon position the implant components with precision. The robot does not perform the surgery — the surgeon does. The technology assists with planning and execution. Research suggests robotic assistance may improve implant positioning accuracy, though long-term outcome data is still accumulating. Not all surgeons use robotic technology, and excellent results are achieved with traditional techniques as well.