Most surgical plates and screws are made of titanium or titanium alloys, with stainless steel as the next most common option. These two metals dominate orthopedic hardware because they are strong enough to stabilize broken bones while remaining reasonably compatible with living tissue. But the material landscape is broader than those two workhorses suggest, and it is shifting. Newer options include cobalt-chromium alloys, biodegradable magnesium, carbon fiber-reinforced polymers, and even shape-memory metals, each chosen for specific surgical situations where the traditional picks fall short.
Titanium and Its Alloys
Titanium earned its place as the default material for orthopedic plates and screws because it checks several boxes at once. It is strong relative to its weight, resists corrosion in the body’s salty environment, and forms a thin oxide layer on its surface that helps bone cells latch on and grow directly against the implant. That process, called osseointegration, is what keeps a plate from loosening over time. Research on human bone cells exposed to surface-treated titanium has shown that osteoblasts ramp up their mineralization rate and switch on key genes involved in bone formation when in contact with the metal.1PubMed Central. Proteomic evaluation of human osteoblast responses to titanium implants over time
The most widely used titanium alloy in orthopedics is Ti-6Al-4V, which contains small amounts of aluminum and vanadium to increase strength. Commercially pure titanium also sees use, particularly where maximum corrosion resistance matters more than peak mechanical strength. In an animal comparison of several implant metals, pure titanium screws required significantly more force to remove than cobalt-chromium screws, reflecting tighter bone integration.2PubMed Central. Osseointegration and biocompatibility of different metal implants–a comparative experimental investigation in sheep
Titanium is not perfect, though. Its protective oxide layer can break down during inflammation, when immune cells release aggressive molecules like hydrogen peroxide and free radicals. This degradation can release metal particles into surrounding tissue, potentially triggering further inflammation in a frustrating feedback loop.3PubMed. Corrosion of titanium under simulated inflammation conditions: clinical context and in vitro investigations Still, compared to stainless steel, titanium releases far fewer metal ions into the body over its lifetime, which is a major reason it overtook steel as the go-to material.
Stainless Steel Still Has a Role
Surgical-grade stainless steel, typically the 316L variety, was the original metal of modern fracture fixation and remains in use today, especially in settings where cost matters. It is cheaper to manufacture than titanium and easier to machine into complex shapes. For temporary implants that will be removed after a bone heals, stainless steel’s lower cost and adequate strength can make it the practical choice.
The tradeoff is biocompatibility. Stainless steel contains nickel, chromium, and molybdenum, and its corrosion resistance relies on a chromium oxide layer that is less stable than titanium’s oxide film inside the body. Bone does not bond as tightly to steel surfaces, and the metal is more prone to releasing ions over time. In the same sheep study that compared multiple implant metals, stainless steel screws showed weaker bone contact than titanium, though they outperformed cobalt-chromium.2PubMed Central. Osseointegration and biocompatibility of different metal implants–a comparative experimental investigation in sheep
Stainless steel plates can also fail mechanically. One documented case involved a 316L compression plate mounted with twelve screws on a patient’s femur. Six months after surgery, the plate fractured through its center. The failure was traced to cyclic loading from walking too soon after the operation, which caused alternating episodes of fatigue cracking. The fracture surfaces showed classic fatigue striations under electron microscopy, with no sign that corrosion played a role. It was a mechanical failure driven by premature weight-bearing.4Engineering Failure Analysis. Premature fracture of a stainless steel 316L orthopaedic plate implant by alternative episodes of fatigue and cleavage decoherence Titanium plates can fail too under similar circumstances, but this case illustrates why proper post-surgical protocols matter as much as the material itself.
Cobalt-Chromium and Shape-Memory Alloys
Cobalt-chromium alloys show up mainly in joint replacement components rather than fracture plates, but they are part of the orthopedic metals family. These alloys are extremely hard and wear-resistant, which makes them well suited for bearing surfaces in hip and knee replacements. For screws and plates, though, cobalt-chromium has a significant drawback: bone does not integrate with it as readily. In the comparative sheep study, cobalt-chromium screws had the lowest removal torque and the weakest bone-to-implant contact of any material tested.2PubMed Central. Osseointegration and biocompatibility of different metal implants–a comparative experimental investigation in sheep
A more novel metal is Nitinol, an alloy of nickel and titanium that has two unusual properties: shape memory and superelasticity. Shape memory means the metal can be deformed and then return to a pre-set shape when warmed. Superelasticity means it can flex far more than conventional metals without permanent deformation, making its mechanical behavior closer to that of bone. A range of Nitinol-based orthopedic devices, including screws, plates, rods, staples, and dynamic fixation systems, have been developed and studied clinically.5PubMed. Nitinol in Orthopedic Applications: Clinical Insights, Performance Challenges, and Future Directions Nitinol staples, for instance, can compress a fracture site as they warm to body temperature, providing constant gentle force across the healing bone. The main concern is its high nickel content, which limits its use in patients with known nickel sensitivity.
Polymer and Composite Plates
Not every surgical situation calls for metal. In craniofacial surgery on children, for example, metal plates would need to be removed as the skull grows, adding a second operation. Bioabsorbable polymer screws and plates avoid that problem. These devices are typically made from polylactic acid (PLLA), polyglycolic acid (PGA), or a copolymer of the two. They hold bone fragments in place during healing and then gradually break down into carbon dioxide and water over months to years. Testing of 1.5-millimeter screws made from an 82/18 blend of PLLA and PGA showed no change in dimensions or physical appearance after 33 days in body-like conditions, confirming they maintain structural integrity through the critical early healing window.6PubMed. Stability of craniofacial PLLA/PGA copolymer bioabsorbable screws
For load-bearing applications where polymers alone would be too weak, carbon fiber-reinforced polyether ether ketone (CFR-PEEK) offers an interesting middle ground. PEEK is a high-performance engineering plastic, and embedding carbon fibers in it creates a composite that is stiff enough to fix bone yet has an elastic modulus much closer to bone than titanium does. That matters because a plate that is far stiffer than the bone it supports can shield that bone from normal mechanical stress, weakening it over time. CFR-PEEK plates have been introduced as an alternative to titanium for procedures like high tibial osteotomy, with the added benefit of being radiolucent, meaning they do not create artifacts on X-rays and MRIs.7PubMed. Biomechanical evaluation of carbon fiber-reinforced polyether ether ketone versus titanium plates for fixation of high tibial osteotomy For surgeons monitoring healing, being able to see clearly through the plate on imaging is a genuine practical advantage.
The Stress Shielding Problem
One of the underappreciated consequences of implant material choice is stress shielding. Bone is a living tissue that remodels in response to mechanical load. When a stiff metal plate absorbs most of the force that would normally travel through the bone, the bone beneath it can actually lose density and weaken. Titanium and stainless steel plates are substantially stiffer than human bone, which creates this mismatch. Composite materials with a lower elastic modulus, closer to bone’s own stiffness, have been proposed as a way to reduce stress shielding while still providing adequate fixation.8Journal of Composites Science. Stress Analysis of Tibial Bone Using Three Different Materials for Bone Fixation Plates This is one of the driving forces behind the development of CFR-PEEK and similar composite plates. The goal is a fixation device stiff enough to hold a fracture steady but not so stiff that it starves the healing bone of the mechanical signals it needs.
Biodegradable Metals
The idea behind biodegradable metal implants is appealing: a plate or screw that holds bone together during healing and then gradually corrodes away, eliminating the need for removal surgery. Magnesium is the leading candidate. It is lightweight, its stiffness is closer to bone than titanium’s, and the body can handle its corrosion products, since magnesium is already present in bone naturally. In a study comparing magnesium and titanium plates for skull fracture repair in miniature pigs, the magnesium hardware demonstrated biocompatibility, adequate mechanical strength, and visibility on X-rays, making it suitable for internal fixation.9PubMed. Osteosynthesis of a cranio-osteoplasty with a biodegradable magnesium plate system in miniature pigs
Magnesium-based screws have already entered clinical use in some regions, but significant hurdles remain. The metal corrodes faster than ideal in the body’s environment, sometimes degrading before the bone has fully healed. That rapid corrosion also releases hydrogen gas, which can form small pockets around the implant. Researchers are working on alloys and coatings that slow the corrosion rate to a more controlled timeline. Iron and zinc alloys have also been explored as biodegradable options, particularly for load-bearing applications where they could offer greater strength than magnesium during the critical healing period.10Metals. Advances and Challenges of Biodegradable Implant Materials with a Focus on Magnesium-Alloys and Bacterial Infections
Surface Coatings and How They Change Performance
The material an implant is made of is only part of the story. Surface treatments and coatings can dramatically change how the surrounding tissue responds to a plate or screw, turning a mediocre surface into one that bone bonds to eagerly.
Hydroxyapatite is one of the most studied coatings. It is a calcium phosphate mineral that is a natural component of bone, so applying it to a metal surface essentially tricks bone cells into treating the implant like bone. In a sheep study, stainless steel screws coated with highly crystalline hydroxyapatite required significantly more force to extract than both uncoated steel screws and titanium-coated screws, indicating tighter bone integration. The uncoated steel screws had visible gaps between the bone and screw surface, while the coated ones showed close contact.11Journal of Orthopaedic Trauma. Improvement of the Bone–Screw Interface Strength with Hydroxyapatite-Coated and Titanium-Coated AO/ASIF Cortical Screws This finding is clinically meaningful because it suggests that coating technology can partially compensate for the inherent biocompatibility disadvantage of cheaper metals like stainless steel.
Anodization is another widely used surface treatment, particularly for titanium. The process uses an electric current to thicken and restructure the natural oxide layer on titanium’s surface, creating a more porous and bioactive film that promotes faster bone attachment.12PubMed Central. Evolution of anodised titanium for implant applications More recent work has combined anodization with calcium and phosphorus treatments to further enhance bone formation on the surface. Pre-osteoblast cell cultures showed increased mineralization on these dual-treated titanium specimens compared to anodized-only controls.13Thin Solid Films. Anodized titanium with calcium and phosphorus surface enhancements for dental and orthopedic implant applications
Antimicrobial coatings represent a different frontier. Infection is one of the most feared complications of orthopedic hardware, and coating implant surfaces with materials that resist bacterial colonization could reduce that risk. In a rabbit study, titanium screws coated with a polyvinylpyrrolidone-polyurethane polymer showed dramatically less tissue inflammation and necrosis than uncoated screws. All rabbits in the coated group had live, cellular bone marrow around the implant, while half the uncoated group had marrow replaced by connective tissue.14PubMed Central. Cytotoxicity of a new antimicrobial coating for surgical screws: an in vivo study These coatings are still largely in the research phase for orthopedic screws, but the early results suggest they could become standard in the future.
Nickel Allergies and Choosing the Right Implant
Roughly 10 to 15 percent of the general population has some degree of nickel sensitivity, and this creates a real clinical problem because stainless steel, cobalt-chromium, and Nitinol all contain nickel. The most common reaction is a delayed-type hypersensitivity that can cause persistent pain, swelling, delayed wound healing, and skin changes around the surgical site. In patients with known nickel allergy, guidelines recommend using titanium or carbon fiber implants instead, since these materials avoid the offending metal.15PubMed Central. Nickel allergy to orthopaedic implants: A review and case series
The tricky part is that many people discover their nickel sensitivity only after surgery, when symptoms appear and other explanations have been ruled out. Skin patch testing before elective orthopedic procedures is not routine, though some surgeons recommend it for patients with a history of jewelry-related skin reactions. If you know that cheap earrings or belt buckles make your skin itch or break out, it is worth mentioning to your surgeon before any procedure involving metal implants.
3D-Printed and Patient-Specific Hardware
Traditional plates and screws are manufactured in standard sizes and shapes. Surgeons bend and adjust them in the operating room to fit the patient’s anatomy, which works well for straightforward fractures but can be suboptimal for complex bone geometry or unusual tumor resections. Three-dimensional printing has opened the door to patient-specific implants designed from CT scans before surgery even begins.
Titanium is the most commonly 3D-printed metal for orthopedic use. The printing process, which fuses metal powder layer by layer with a laser or electron beam, can create internal porous structures that mimic the architecture of natural bone. These pores encourage bone to grow into the implant rather than just onto its surface, improving long-term stability.16PubMed Central. An overview of 3D printed metal implants in orthopedic applications: Present and future perspectives In one series, custom 3D-printed titanium plates were used in twelve patients after tumor removal around the knee. The plates matched the bone surface precisely, and gait analysis showed good knee function during daily activities.16PubMed Central. An overview of 3D printed metal implants in orthopedic applications: Present and future perspectives
The ability to print porous structures also addresses the stress shielding problem. By controlling the density and pattern of pores within a titanium plate, engineers can tune its effective stiffness to be closer to bone, reducing the mechanical mismatch that weakens bone over time.17BME Horizon. Personalized 3D-printed bone plates in fracture management: recent advances and future perspectives Custom-printed implants remain more expensive and time-consuming to produce than off-the-shelf hardware, so they are currently used mainly for complex reconstructive cases. As printing speeds increase and costs drop, broader adoption seems likely.
When Hardware Comes Out
A question many patients ask after their fracture heals is whether the plates and screws should be removed. The answer depends on the material, the location, and how the patient feels. Titanium plates that have integrated tightly with bone are often left in place permanently, since removal surgery carries its own risks and the hardware is generally well tolerated. Stainless steel hardware, which integrates less tightly and is more likely to cause irritation, is removed more frequently.
In a large patient survey on implant removal, the most common reasons for taking hardware out were pain and impaired function. Among those patients, the results were overwhelmingly positive: about 96 percent reported decreased pain after removal, and roughly 72 percent reported improved function. Even among patients who experienced complications from the removal procedure itself, two-thirds said they would choose removal again.18PubMed Central. Metal implant removal: benefits and drawbacks – a patient survey
The indications for removal vary globally. In a study from an Indonesian hospital, the most common reason for hardware removal was conversion to a different fixation method, followed by infection and then patient request. The only complication observed was disturbed wound healing, which occurred in about 16 percent of cases, while 84 percent healed without problems.19International Journal of Integrated Health Sciences. Indications and Complications of Orthopedic Hardware Removal in an Indonesian Tertiary Hospital: A Descriptive Study The lack of universal guidelines means the decision often comes down to a conversation between patient and surgeon, weighed against the specific hardware material and the patient’s symptoms. Biodegradable implants, when they mature enough for routine use, would sidestep this decision entirely.