LFIT CoCr V40TM Femoral Heads
One of the most recent and controversial hip device recalls was first announced by Stryker on August 29, 2016, regarding its LFIT V40 Cobalt-Chromium Femoral Head, an artificial hip component that’s been frequently employed in hip replacement / revision surgeries worldwide since its release in the early 2000’s.
According to Stryker’s “Urgent Medical Device Recall” notice, over 4,000 lots of the product, all manufactured before 2011, needed to be recalled because of “higher-than-expected” failure rates, based on a high volume of complaints from patients. These complaints revealed that the affected lots pose a number of “potential hazards” that have caused patients to suffer severe complications such as:
- Loss of mobility
- Device breakage
- Uneven leg lengths
- Pain from device loosening
- Joint instability or dislocation
- Adverse local tissue reactions
- Inflammatory immune system reactions
- Need for revision surgery due to intense pain or risk of accident
As later reported by the FDA, Stryker distributed this notice via e-mail to all of its relevant branches / agencies, instructing them to “quarantine” any affected units.
Federal Agencies Issue Stryker Alerts
Shortly after Stryker announced its “voluntary recall” of the affected LFIT V40 Femoral Head lots, the FDA as well as governmental agencies from other countries issued urgent nationwide alerts to doctors and patients
- Canada. Health Canada actually published its medical device recall alert for Stryker LFIT V40 Femoral Heads on August 24, 2016—several days before Stryker sent out its official internal company notice on August 29. The Health Canada alert was distributed to healthcare professionals as well as the general public.
- USA. On November 9, 2016, the FDA released information about the recalled Stryker devices on the official FDA website.
Stryker has been heavily criticized for the lack of information included in its recall notice, especially regarding how no reasons were given for the unexpected failures mentioned in the recall—the possible causes are merely described as still “under investigation.”
Yet a wave of hip failure lawsuits say Stryker did have extensive information about the source of the problem at the time it sent out the 2016 notice. This recall, plaintiffs assert, was instigated not only by the consumer complaints mentioned in the notice, but also by research published in prominent orthopedic journals that Stryker should have been aware of.
Stryker Hips Causing “Catastrophic Failure”
One recent journal article, published by medical researchers at the Thomas Jefferson University Hospital in Pennsylvania, specifically looks at patients suffering from complications of Stryker hip replacements. The authors describe 5 case studies of patients from their hospital, all of whom who received Stryker hip components and experienced “catastrophic implant failure” —complications severe enough to necessitate immediate revision surgery.
The researchers explained that the specific problem encountered by all of these patients was a complication termed “taper lock failure,” which is when the femoral head and hip stem in a replacement hip no longer securely lock together—whether it’s due to loosening, wear, or breakage—and suddenly come apart, often causing intense pain and rendering the patient unable to move.
Though this type of failure is thought to be much rarer than complications such as inflammation and other “adverse local tissue reactions” more commonly associated with modern hip implants, the authors felt their findings indicated that surgeons should be acutely aware of how to diagnose taper lock failure and recognize revision surgery is the necessary treatment for it.
What Causes “Dangerous” Hip Device Side Effects?
To help better understand what conditions lead to taper lock failure and other severe complications, let’s take a look at the design principles behind modern hip replacement implants.
The Aims Of Hip Replacement
The hip joint is a ball-and-socket joint that allows the legs a wide 3D range of motion. It’s comprised of the rounded top end of the femur (the “ball”), which fits the acetabulum (the “socket”) of the pelvic bone.
In a healthy, well-functioning hip, the acetabulum is lined with cartilage that serves to cushion the femoral head as the joint is articulating. The surface of the cartilage in the hip is also covered with a special lubricant that helps absorb shocks and allows the joint to move smoothly. But over time, the cartilage gets worn down from use, and bone-on-bone friction between the femoral head and the acetabulum causes movement to be increasingly difficult and painful.
In addition to normal wear and tear occurring over a person’s lifetime, loss of cartilage can be accelerated and exacerbated by physical injuries or joint or bone-related conditions such as arthritis and osteoporosis. Patients seeking hip surgery to alleviate discomfort and pain from everyday movement have two main options:
In hip resurfacing, surgeons shave off the worn-out / damaged surface of the femoral head and fit it with a plastic, ceramic, or metal cap, along with new synthetic lining for the acetabulum to replace the depleted cartilage.
One advantage of opting for hip resurfacing is that it allows patients to get at least several more years of use from portions of their original hip joint while still affording them the possibility of having a total hip replacement in the future.
However, many patients in need of hip replacement cannot have hip resurfacing—this surgery doesn’t replace as much bone as total hip replacement, so the best candidates for this type of hip replacement are patients who are younger and / or still have a considerable amount of healthy bone left.
Hip Replacement Surgery
This option, commonly termed total hip replacement (THR) or total hip arthroplasty (THA), involves completely removing the femoral head, acetabulum, lining, and part of the femur and replacing them with devices made from ceramic or various types of metal or plastic.
The majority of Americans undergoing hip replacement surgery are senior citizens, but the number of younger patients opting for the surgery grows each year, as reported by various news outlets such as the Washington Post. Researchers believe this is partially due to a trend towards a more active lifestyle, as increased physical activity, while beneficial for overall health, also not surprisingly puts more strain on one’s joints. Also, doctors are advising younger, active patients to undergo hip replacement for preventative measure to ensure their well-being remains optimal.
Successful hip replacement will increase stability and eliminate or minimize pain / discomfort from hip movement. Early hip prosthetics were “monobloc” in nature — that is, the artificial femoral head and the femoral stem were already connected to one another in more or less one piece that would be attached to the femoral stem and designed to fit into the replacement acetabular shell.
This rigid design lacked flexibility and often made it challenging for surgeons to achieve proper fit and leg length / hip balance for a wide range of patients.
Modern Hip Devices
This is why, starting in the 80’s, orthopedic manufacturers began developing “modular” hip systems, in which the femoral head and the hip stem are separate parts that come in various sizes and shapes.
In addition to facilitating a far more individualized fit, modular hip devices were designed to make it easier to do revision surgery by allowing the surgeon to potentially replace only the necessary part of the hip system rather than having to remove and replace the whole thing regardless of wear.
Questionable Modular Design Choices?
Orthopedic researchers and medical professionals were initially excited about the development of modular hip devices and hoped they would resolve troublesome issues of individual fit and long-term wear experienced by many hip arthoplasty patients. Many manufacturers aimed not only to facilitate fit and ease of replacement, but also to reduce overall wear.
But some of the ways manufacturers tried to achieve these aims ended up backfiring, instead potentially predisposing the devices to early failure , according to recent lawsuits and medical research articles.
Increased Corrosion Releases Toxic Metal Ions
Metal debris from modern hip replacement systems builds up and can cause hip implants to corrode, which can lead to pain, instability, and even breakage necessitating revision surgery.
Some corrosion is unavoidable, as the human body is a harsh chemical environment for a metal device, especially one designed to remain in the body for years. But experts believe there are 2 main design features that may particularly facilitate the corrosion process in modern metal-on-metal and metal-on-polyethylene hip replacement devices:
Choices of Metals May Cause Galvanic Corrosion
Metals can vary greatly in how resistant they are to corrosion and oxidation–for example, some metals readily form protective surface films in a liquid environment. Indeed, Stryker likely opted to use cobalt, chromium, and titanium alloys for various useful characteristics such as tensile strength, malleability, and corrosion-resistance. However, the potential problem lies in how Stryker selected cobalt / chromium for the femoral head and titanium for the hip stem rather than using the same metal or alloy for both parts.
When two types of metal are in contact with one another in an electrically conductive liquid environment, if one metal is significantly less corrosion-resistant than the other, then it will corrode faster than it would on its own. Thus a metal hip device composed of dissimilar metals would be expected, based on fundamental principles, to experience increased corrosion in comparison to a single-metal or single-alloy device.
Fretting Corrosion in the Femoral Head – Hip Stem Junction
The other main potential design issue in Stryker hip devices lies in the particular type of interface Stryker chose for connecting the femoral head and the hip stem. The LFIT V40 Femoral Head fits into its hip stem via a trunnion sleeve that rotates. This rotating sleeve was meant to reduce friction between the femoral head and the acetabular cup, which it does–but at the expense of allowing for another, more problematic source of friction: Fretting corrosion in the trunnion sleeve.
Fretting corrosion occurs when two surfaces that are meant to fit snugly against one another without movement end up rubbing against each other due to some unavoidable external force. In the case of hip replacement devices, the femoral head is supposed to lock securely into the femoral neck, but vibration from movement of the hip joint inevitably leads to some friction at the head-neck interface, resulting in fretting corrosion.
The degree of fretting corrosion can vary depending on the taper lock design; the geometry of the head taper seems to be especially important according to published research.
Hip Implant Side Effects
A worn-down, broken, or otherwise malfunctioning artificial hip device can cause a number of deleterious side effects, including chronic pain, cardiovascular problems, Common symptoms include:
- Pain around the implant(s)
- Loosening of the implant
- Difficulty walking
- Psychological changes
However, it’s common for failing hip implants to only exert noticeable symptoms after it’s too late — when the damage is already so extensive that the patient urgently needs revision surgery to alleviate intense pain.
Risk Factors for Hip Replacement Failure
Certain patients may be at a higher risk for hip replacement complications. These risk factors are mostly related to the amount of wear the hip joint is expected to experience:
- Small / petite frame (puts more pressure / tension on the vulnerable parts of the artificial hip joint)
- Overweight / High BMI (more pressure / tension on joints in general)
- Active lifestyle (increased physical activity leads to increased / more frequent wear)
- Men are at higher risk than women (men tend to be more physically active than women)
- Allergies / sensitivities to the types of metal and plastic used in hip prosthetics
None of the Stryker hip recall notices issued so far mention any of these crucial risk factors.
Patients Take Legal Action Against Stryker
After being forced to undergo early hip revision surgery due to taper lock failure or other possibly design or manufacture-related hip replacement complications, dozens of patients have already filed Stryker hip lawsuits over the recalled LFIT V40 Cobalt-Chromium Femoral Head, and many more are believed to be in the process of filing.
The plaintiffs behind some of these cases, which all request over $75,000 in relief from Stryker to compensate for pain, suffering, and loss allegedly caused by the company’s negligence, believe the growing numbers of similar hip lawsuits will soon be staggering, leading them to request consolidation by Multi-District Litigation. This request will be reviewed on March 30, 2017, by the Judicial Panel on Multi-District Litigation.
If MDL status is granted to these cases, it won’t be first time that Stryker faces a large number of cases in an MDL. After the company recalled its Rejuventate and ABG II hip systems in 2012, thousands of lawsuits, some of them grouped together in MDLs or MCLs (Multi-County Litigations), were filed and eventually resolved in 2014 with a large global Stryker hip settlement.
More Information On Stryker Hip Implants