TLDR: A press-fit hip replacement anchors a new hip using precise mechanical contact with living bone instead of cement. During surgery, the surgeon shapes the thigh bone so a slightly oversized titanium stem wedges in tightly, gripping right away so patients can usually bear weight soon after. Over about six weeks, bone grows into or onto the implant surface for a lasting bond. More than 90 percent of hip replacements in the United States are now cementless. It suits active patients with healthy bone, while cement remains the better choice for some weaker bone.
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A press-fit hip replacement holds your new hip in place using a tight mechanical fit against your own bone, not glue or cement. In my practice at the Bone and Joint Institute of Tennessee in Franklin, this is the approach I use for most patients who need a new hip. After more than twenty years of doing this and performing hundreds of joint replacements each year, I have seen how reliably a well-seated cementless stem performs. Here is exactly how it works, what happens in the operating room, and how I help patients decide if it is right for them.
What is a press-fit hip replacement?
A press-fit hip replacement is a hip implant that anchors to bone through a snug, friction-based fit rather than bone cement. The word “press-fit” describes the technique: I prepare the upper thigh bone (the femur) to a precise shape, then seat a metal stem that is slightly larger than the space I made. That intentional size mismatch creates pressure, called hoop stress, that grips the stem the moment it goes in.
Doctors also call this a cementless hip replacement. Both terms mean the same thing. The implant is usually made of titanium alloy, a metal whose flexibility is close to natural bone, so it shares load with the femur in a healthy way.
How is press-fit different from a cemented hip?
The difference is what holds the implant still. A cemented hip uses a fast-setting grout (a bone cement called polymethylmethacrylate) to lock the stem in place during surgery. A press-fit hip skips the cement and relies on a tight fit plus, later, your own bone growing into the surface. In my experience, the cementless approach gives younger, active patients a durable bond that can last for decades.
How is a press-fit hip stem placed in the operating room?
I place a press-fit hip stem by carefully shaping the femoral canal and then seating a slightly oversized stem so it wedges tight. The goal at this stage is simple: rigid contact and almost no movement between metal and bone.
First, I prepare the inside of the thigh bone. For most primary hip replacements, I use a tool called a broach to compact and shape the soft inner bone of the upper femur (the metaphysis). This preserves bone and creates a precise socket for the stem.
Next, I seat the implant. The stem is a bit larger than the prepared canal. As I drive it in, that hoop stress clamps it tight. For this grip to work, the gap between bone and metal must stay under 50 microns, thinner than a hair, with almost no movement. Too much motion lets scar-like tissue form instead of solid bone. That can be painful and loose.
What does “broaching” versus “reaming” mean?
Broaching and reaming are two ways I prepare the bone, chosen by where the stem needs to grip. Broaching shapes the wider, softer top of the femur and is standard for routine hip replacement. Reaming prepares the narrow shaft lower down (the diaphysis) and is more common in revision surgery, when the upper bone is weak or already used. Some stems grip the top of the bone, some grip the shaft, and the design I pick decides which technique I use.
How does the bone hold onto a cementless implant?
Your bone holds onto a cementless implant by growing directly into or onto its textured surface over the first several weeks. This biologic bond is the long-term anchor. The tight press-fit gives short-term stability; living bone gives lasting stability.
Bone ingrowth versus bone on-growth
There are two ways bone attaches to the metal. Ingrowth happens when bone grows down into a porous, sponge-like coating with tiny pores. On-growth happens when bone grows onto a roughened, grit-blasted surface that has texture but no deep pores. Ingrowth tends to make a stronger bond per area. On-growth surfaces make up for it with more coverage. Many modern stems also carry a thin hydroxyapatite coating, a natural bone mineral that helps bone attach faster.
Why titanium and not a stiffer metal?
I favor titanium because it flexes more like real bone. When an implant is far stiffer than bone, it carries too much load. The bone around it can then thin out over time. We call this stress shielding. Titanium shares the load more evenly, which helps protect bone and can reduce thigh discomfort.
Who is a good candidate for a press-fit hip replacement?
The best candidates for a press-fit hip replacement are patients with healthy, strong bone that can grip the implant and grow into it. This often includes active adults and many patients under retirement age with good bone stock. The technique has a long, proven track record in this group.
Bone quality matters more than age alone. Some patients have very thin or soft bone (advanced osteoporosis). Others have a wide, funnel-shaped canal, sometimes called a stovepipe femur, or weak bone from past surgery. These patients may not grip a press-fit stem well. For those patients, I often recommend a cemented stem, which can give excellent fixation when bone is fragile.
If hip pain is limiting your daily life, the right way to find out which option fits you is a focused evaluation with X-rays. That is something I do every week for patients across Franklin, Brentwood, Nashville, Nolensville, Murfreesboro, Columbia, and the rest of Middle Tennessee.
What are the benefits and risks of a cementless hip stem?
A cementless hip stem offers a durable, bone-integrated bond with strong long-term results, but like any surgery it carries real risks worth understanding.
Benefits
- Lasting fixation: once bone grows in, the bond is biologic and built to last for decades in suitable patients.
- Early weight bearing: the tight initial grip usually lets patients put weight on the leg soon after surgery.
- Bone-friendly load sharing: titanium flexes near bone, helping limit stress shielding.
- No cement to wear or break down: there is no cement mantle that can crack over many years.
Risks
- Thigh pain: a portion of patients feel aching in the thigh, especially early on; for most it eases over the first year or two.
- Stress shielding: bone around a stiff or large stem can thin over time, though this rarely causes problems.
- Fracture during seating: because the stem is wedged in tightly, the bone can crack during surgery; a collar on the stem can help reduce this risk.
- Loosening: if bone does not grow in well, the implant can loosen and may need revision.
I keep these risks low with careful patient selection, precise planning called templating, and matching the right stem to your bone shape.
Press-fit or cemented: how do I decide?
I decide between press-fit and cemented mainly by your bone quality on X-ray, plus your age, activity level, and health. Strong bone that can grip and grow favors press-fit. Soft or thin bone often favors cement. There is no single best answer for everyone, and that is the point: the choice is personalized to you.
Robotic-assisted planning can also help me position any hip implant precisely. You can read more about robotic hip replacement and about the conditions that lead to surgery, such as hip arthritis and hip impingement.
If you are weighing hip replacement and want a clear, honest answer about your options, I would be glad to see you. You can request a consultation with Dr. Calendine or call our office at (615) 791-2630. We are located at Bone and Joint Institute of Tennessee, 3000 Edward Curd Lane, Franklin, TN 37067.
This information is for educational purposes only and should not replace professional medical advice, diagnosis, or treatment. Surgical procedures carry risks and benefits that vary for each individual. Always discuss your specific situation, risks, and expected outcomes with a qualified orthopaedic surgeon.
