Michigan-based Stryker Corp. began as the Orthopedic Frame Company in the 1940s. Over the years the company expanded and now markets 57,000 products worldwide. Its net sales reached $9.9 billion in 2015, and 13 percent of those sales came from hip replacement products, according to the company’s annual report.
The company introduced its newest hip replacement product, the ADM X3 Mobile Bearing Acetabular System, in 2010. The ADM X3 is an acetabular component that uses a dual mobility cup concept that has been proven to reduce the risk of dislocation and improve stability. It’s made from polyethylene, a type of plastic designed to increase range of motion, improve joint stability and reduce the risk of wear.
Stryker also sells numerous femoral components, including press-fit stems, cemented stems and revision components. Its press-fit stems include models from the Accolade and Secur-Fit product lines, and its revision components include products from the Restoration product line.
A 2008 study that analyzed 105 patients who received Secur-Fit hip implants concluded that the stems “performed exceedingly well” during the 5- and 10-year follow-up period. Four patients who had an elevated rim line developed osteolysis, a complication characterized by a loss of bone tissue.
- Titanium Acetabular Shell
- Trident Acetabular Shell
- Trident Alumina Ceramic Bearing
- Trident Polyethylene Bearings
In addition to hip implant components, Stryker manufactures robotic technology called Mako that helps surgeons perform total hip replacement procedures. More than 10,000 hip replacement procedures had been performed using Mako by 2015.
But some Stryker products have not been as effective. The company used a proprietary titanium alloy called TMZF and interchangeable components in many of its hip systems. The alloy is a mix of titanium, molybdenum, zirconium and iron. Stryker claimed that the patented blend resisted the effects of corrosion and fretting, which occurs when small particles of metal flake off the implant.
However, post-market data revealed evidence of corrosion and fretting, and patients claim the devices caused serious side effects, including loosening of the implant and the release of toxic metals. Stryker recalled two of its hip replacement systems that contained the alloy.
Stryker’s Rejuvenate, ABG II and Other TMZF Systems Complications
Unlike typical hip implant systems, which include a one-piece neck and stem called a monoblock design, Stryker’s Rejuvenate, ABG II and other TMZF systems included several neck and stem components.
The ABG II system had eight right stems, eight left stems and 10 modular necks, which were supposed to offer greater stability and less bone stress than other models. Stryker marketed the Rejuvenate hip, with six stems and 16 necks, to younger patients.
Stryker designed these modular, interchangeable systems to give surgeons custom-fit devices to tailor to the needs of each patient. These devices were supposed to be longer lasting and have a better range of motion. However, the Rejuvenate and ABG II systems caused complications related to their metallic components.
Unlike other metal-on-metal components that are the subject of numerous lawsuits involving hip replacements, Stryker products did not contain metal-on-metal ball-and-socket components that rubbed against one another. The necks of Stryker products were made of chromium and cobalt that rubbed against titanium coating on the stem. Thus, metal particles could rub off and enter other parts of the body. That’s what happened to thousands of patients.
In July 2012, Stryker voluntarily recalled all of its Rejuvenate and ABG II hip replacements from the market because of the potential for fretting and corrosion that could cause pain, swelling and tissue damage. The company advised doctors to examine and perform blood work on patients who received the implants.
The U.S. Food and Drug Administration classified the recalls as Class II recalls and determined the cause of the recall to be “defective design.” Thousands of people harmed by the hip implants sued Stryker because their implants failed and they had to have revision surgery. The company resolved many of the claims in a billion dollar settlement in 2014, but more than 1,000 lawsuits are still pending.
Other Stryker products also contained TMZF coating, including Stryker’s Accolade, Citation and Meridian hip components.
New Model and Material Replace Accolade TMZF
The Accolade II replaced the Accolade TMZF in the U.S. market. It has an underlying base made from a commercially pure plasma sprayed titanium alloy called Ti-6Al-4. A portion of the stem is covered in a proprietary version of a calcium compound called hydroxylapatite (HA). Stryker calls its version of the material PureFix HA. The Accolade II is a similar stem that uses a metamorphic wedge designed to fit a range of bone sizes.
The Accolade II the latest product in the Accolade Hip System that has been implanted in more than 500,000 patients. The Accolade II comes in 12 different sizes and has 132 and 127 degree offset options. It may avoid problems with the TMZF model.
The older Accolade TMZF implant could cause corrosion and fretting if used with cobalt chromium femoral heads. But the complications were less likely if it was used with Stryker’s ceramic heads.
A 2011 study analyzed 200 patients who received 214 Accolade TMZF implants. Five patients required revision surgery because of loosening, infection, instability or wear. The average follow-up time was 7.6 years. The authors concluded the implant demonstrated a “high success rate” that provided “support for its continued use.” They published their work in the Journal of Arthroplasty.
Please seek the advice of a medical professional before making health care decisions.