Stryker hip replacements are built from a combination of titanium alloys, cobalt-chrome alloys, advanced polyethylene plastic, and sometimes ceramic. Each component of the implant uses a different material suited to its specific job, whether that’s anchoring into bone, bearing weight, or providing a smooth surface for the joint to glide on. The exact combination depends on which Stryker system your surgeon selects and your individual needs.
The Main Components of a Hip Replacement
A total hip replacement has four basic parts: a femoral stem that fits down into your thighbone, a femoral head (the “ball”) that sits on top of the stem, an acetabular shell (the “cup”) that lines your hip socket, and a liner that sits inside the cup for the ball to move against. Each of these parts is made from a different material, and Stryker offers several options across its product lines.
Femoral Stem: Titanium Alloy
The stem is the long piece that anchors the implant inside the hollow center of your thighbone. Stryker primarily uses titanium alloy for this component. In cementless designs, the stem has a roughened or porous surface so that your natural bone grows directly into it over time, locking it in place without the need for bone cement.
Stryker’s Tritanium technology takes this further with 3D-printed titanium. Instead of machining a solid piece of metal, additive manufacturing builds up layers of titanium alloy with precisely controlled pore sizes and strut widths. This creates a structure that mimics the texture of natural bone. In animal studies, 3D-printed porous titanium showed superior bone ingrowth compared to traditional implant surfaces, with 20% to 24% of the available pore space filling with new bone. That biological bonding between the implant and your skeleton is what gives the replacement its long-term stability.
Some Stryker stems also receive a coating of hydroxyapatite, a compound made primarily of calcium and phosphate. These are the same minerals found in your own bone, and the coating encourages your body to bond with the implant surface more quickly in the early weeks after surgery.
Femoral Head: Metal or Ceramic
The ball that replaces the top of your thighbone is typically made from either cobalt-chrome alloy or ceramic. Cobalt-chrome is extremely hard, polishes to a very smooth finish, and resists scratching during the constant motion of walking and bending.
Stryker also offers ceramic femoral heads made from a fourth-generation material called BIOLOX delta. This is a composite of alumina (aluminum oxide) and zirconia (zirconium oxide), along with small amounts of strontium oxide and chromium oxide. The combination produces a head that is harder and more scratch-resistant than metal, generates fewer wear particles, and is highly biocompatible. Ceramic heads are a common choice for younger, more active patients because of their exceptional durability.
Acetabular Shell: Titanium
The cup that your surgeon presses into your hip socket is also made from titanium alloy. Like the stem, it often features a porous or 3D-printed outer surface designed for bone ingrowth. The shell may be held in place with screws initially, but the goal is for your pelvic bone to grow into and around the implant so it becomes a permanent part of your skeleton.
Acetabular Liner: Polyethylene or Ceramic
Inside the metal cup sits a liner that the femoral head articulates against. The most common option is a highly cross-linked polyethylene, essentially an ultra-durable medical-grade plastic. Stryker’s version, called X3, goes through three rounds of radiation and heat treatment to strengthen the molecular bonds in the material. Each cycle involves gamma radiation followed by eight hours of heating at 130°C, for a total radiation dose of 9 Mrad. The result is a plastic that wears down extraordinarily slowly.
In clinical measurements using precision imaging, X3 liners showed a wear rate of just 0.015 millimeters per year in the first two years after surgery. To put that in perspective, that’s roughly the thickness of a single human hair annually. This low wear rate matters because tiny plastic particles shed from the liner can trigger an immune response over time, potentially loosening the implant. Less wear means fewer particles and a longer-lasting replacement.
For patients who receive a ceramic femoral head, a ceramic liner can also be paired with it, creating a ceramic-on-ceramic bearing. This combination produces the least wear of any current option, though the polyethylene liners have become so durable that both choices perform well over decades.
Options for Metal Sensitivity
Some people have allergies or sensitivities to metals like nickel or cobalt, both of which are present in cobalt-chrome alloys. Stryker addresses this with products like the Triathlon Gold knee system, which uses a titanium alloy component coated with titanium nitride. This gold-colored ceramic coating creates a barrier between the cobalt-chrome and your body. While this specific product is designed for knees, the principle applies across Stryker’s approach: ceramic femoral heads and highly cross-linked polyethylene liners can eliminate direct contact between cobalt-chrome and your tissues in hip replacements as well. If you have a known metal allergy, your surgeon can select a combination of components that avoids the problematic materials.
A Note on Recalled Designs
Not every material combination Stryker has used worked as intended. In 2012, the company recalled its Rejuvenate and ABG II hip stems. These modular designs used a cobalt-chrome neck piece attached to a stem body made from TMZF alloy, a titanium-based metal developed specifically for orthopedic use. The junction between these two different metals caused corrosion and released metal debris into surrounding tissue. The recall affected tens of thousands of patients and led to significant legal settlements.
Current Stryker hip systems have moved away from this modular neck design. The stems used today are single-piece constructions that eliminate the metal-on-metal junction that caused problems. If you received a hip implant before 2012 and are unsure whether it was part of the recall, your surgeon’s office can identify your specific implant from your medical records.
How Robotic Surgery Affects Materials
Stryker’s Mako robotic system, now in its fourth generation, doesn’t change the materials in the implant itself. What it changes is how precisely those components are positioned. The robot uses a 3D model of your anatomy to help the surgeon place the cup at the exact angle and the stem at the exact depth planned before surgery. Better positioning means the bearing surfaces wear more evenly, which can extend the life of whatever materials are used. As of 2025, Stryker has expanded the Mako platform to include revision hip surgery, allowing robotic assistance when a worn-out implant needs to be replaced with a new one.