Major Alert for Stryker Hip Implant Recipients with Large Femoral Heads
Important Information for all individuals with Stryker Hip Implants
If you or a loved one was implanted with a Stryker Hip Implant that has a Large Femoral Head Component, please take note: Recent worldwide developments
have resulted in the possible voluntary recall of specific hip implant femoral heads by Stryker Corporation in the United States. Specifically, the safety of certain catalog numbers of Stryker’s LFIT™ Anatomic CoCr V40™ Femoral
Heads has been called into question. Many Stryker Hip Implant Recipients are asking the following questions:
What recent international events may have prompted Stryker Corporation to reassess the safety of some of its LFIT™ Anatomic CoCr V40™ Femoral Heads?
Two international events have raised questions about the safety of
some of Stryker’s large femoral heads: 1) A mandatory recall of certain catalog numbers of Stryker’s LFIT™ Anatomic CoCr V40™ Femoral Heads was initiated in Canada; and 2) A Hazard Alert was issued by the Australian government
regarding specific catalog numbers of Stryker’s LFIT™ Anatomic CoCr V40™ Femoral Heads.
On August 24, 2016, the Canadian Government initiated a mandatory recall of the aforementioned Stryker LFIT™ Anatomic CoCr V40™ Femoral Heads. Similarly, the Australian Registry issued a Hazard Alert regarding these Stryker Femoral Heads on September
27, 2016. Both the Canadian Government and Australian Therapeutic Goods Administration (TGA) indicated that these large femoral heads made by Stryker were linked to a higher-than expected incidence of failure of the Stryker hip
implant taper locks at the Stryker Femoral Head-Neck Junction. It is important to note that these specific metal hip components have NOT yet been a part of any mandatory recall by the Food and Drug Administration (FDA) in the United
What are the potential issues, problems, and dangers associated with the use of large femoral heads in hip implants?
According to a journal article by the National Center for Biotechnology Information (NCBI), total hip
arthroplasty is considered to be “one of the most successful orthopedic interventions of its generation.” Despite this “success”, the industry as a whole has taken a beating over the past few years due to the recalls of some hip
implants, and problems with other hip implants.
Starting around 2006, there was a trend in the orthopedic community towards the use of larger femoral heads as a means of improving stability and free range of motion. There are, however, disadvantages to these larger femoral heads, including: more wear
in metal on polyethylene bearings; elevated levels of metal ions; adverse local tissue reactions, and ALVAL (aseptic lymphocytic vasculitis-associated lesions).
These issues are more likely to occur in hip implants with larger femoral heads, and additional large femoral head problems continue to surface. Recently, a BioMed Research International article discussed head-neck taper corrosion in hip arthroplasty.
While modularity at the head-neck junction became popular in the 1980’s, instances of taper corrosion were not reported until the early 90’s. In more recent years, the contributions of fretting and corrosion at the taper junction
of hip implants are increasingly being recognized, and are becoming a cause for concern.
In studies that have examined the efficacy of femoral head size and stem pairings, there have been some notable observations pertaining to large femoral heads. One study in particular looked at CoCr alloy head and stem pairings that featured 12/14 mm
tapers with metal-on-polyethylene articulations. The study found that a significant increase in taper fretting and taper corrosion was seen in the 36mm femoral heads as compared to the 28mm femoral heads. The type of corrosion
identified was referred to as Mechanically Assisted Crevice Corrosion (MACC).
This mechanically-assisted crevice corrosion was also seen in a separate retrieval study which looked at 90 modular implants. In that study, taper fretting and taper corrosion damages varied, related to the type of articulation and the femoral head size.
Articulation-related corrosion appears to be more likely in large femoral heads which are 36mm and greater and that are paired with a cross-link polyethylene liner, or no liner at all. Taper offset in smaller tapers, and head angles
which are less than the neck angle may also contribute to taper fretting and taper corrosion.
When there are large amounts of corrosion in a hip implant device, the taper may separate from the bone (disassociation), or the femoral head and neck interface may wear down or degrade (trunnionosis). Other potential dangers include the deposition of
metallic debris into surrounding tissue (metallosis), the development of growths around the implant (pseudotumors), and the death of nearby tissue (tissue necrosis). Broken bones, dislocation, and even total hip failure can also
occur, and sometimes require femoral head hip implant revision surgery.
What specific issues, problems, and dangers have been linked to Stryker’s LFIT™ Anatomic CoCr V40™ Femoral Heads?
Both the Canadian Government Recall and the Australian TGA Hazard Alert regarding certain Stryker LFIT™
Anatomic CoCr V40™ Femoral Heads were based on higher than expected incidences of failure of the Stryker taper locks at the Stryker femoral head-neck junction. There may however be some more specific reasons as to why this particular
Stryker Femoral Head is having problems:
What is Mechanically Assisted Crevice Corrosion?
Mechanically Assisted Crevice Corrosion or Fretting-initiated Crevice Corrosion is a type of “run-away” corrosion where fretting is no longer required for the corrosion
to continue. To explain this more easily, “fretting” is simply the wear that occurs between two opposing surfaces, and “corrosion” is the gradual deterioration of a metal by a chemical and/or electrochemical reaction with its environment.
So, whenever a hip implant component incurs wear or fretting, it exposes more of its surface area to the potentially corrosive environment of the surrounding body fluids. Play or toggle at the bore-taper junction (small taper with
offset design and head angles less than neck angles) can contribute to movement based wear, and subsequently corrosion. If this movement results in enough wear/fretting/crevice formation, then corrosion may reach a level where
further wear is no longer required for it to continue – and this is known as mechanically assisted crevice corrosion.
What is Galvanic Corrosion?
Galvanic Corrosion is an electrochemical process by which one metal immersed in the presence of a dissimilar metal deteriorates at an accelerated rate when the two metals are placed in electrical
contact. One metal (the cathode, or positively charged metal) is actually protected while the other metal (the anode, or negatively charged metal) is corroded, as electrons basically flow from the “anode” metal to the “cathode”
metal. When galvanic corrosion occurs in hip implant components, it is usually because the femoral stem and femoral head of the hip implant are made of two different metals. With the two metals immersed in body fluids, they are
essentially placed in electrical contact, and galvanic corrosion can ensue. Galvanic Corrosion is more likely to occur when mismatched metals are implemented, and the changes in local chemistry within the crevices disrupt the protective
oxide layer on the taper. More specifically, titanium stems (Ti-6AI-4V) paired with cobalt and chromium (CoCr) femoral heads can trigger galvanic corrosion, with a higher level of material loss from the bore of the head than from
Is the Stryker LFIT™ Anatomic CoCr V40™ Femoral Head prone to Mechanically Assisted Crevice Corrosion and/or Galvanic Corrosion?
The catalog of Stryker LFIT™ Anatomic CoCr V40™ Femoral Heads that has recently come under
fire is most closely associated with four Stryker femoral stems – The Stryker Accolade TMZF, The Stryker Accolade 2, The Stryker Meridian, and The Stryker Citation. It is possible that the high incidence of Stryker taper lock failures
associated with Stryker’s LFIT™ Anatomic CoCr V40™ Femoral Heads may be attributable to Mechanically Assisted Crevice Corrosion due to the femoral head offsets as well as the size of the tapers. It is also possible that the Stryker
Accolade TMZF stem may be particularly prone to causing Galvanic Corrosion due to the metallic dissimilarity between the Chromium-Cobalt V40 femoral head and the Titanium-Molybdenum-Zirconium-Ferrous coating on the stem.
What are the potential dangers associated with the Stryker LFIT™ Anatomic CoCr V40™ Femoral Head?
Stryker is believed to have issued a notice to Orthopedic Surgeons about the potential dangers of these Stryker LFIT™
Anatomic CoCr V40™ Femoral Heads, including: 1) Disassociation of the Femoral Head from the Hip Stem; 2) Fractured Hip Stem Trunnion; Excessive Metallic Debris; 3) Insufficient Range of Motion (ROM); 4) Insufficient Soft Tissue
Tension; Noise; 5) Loss of Implant: Bone Fixation Strength; 6) Excessive Wear Debris (Polymeric); and/or 7) Implant Construct with a Shortened Neck Length; These aforementioned potential dangers of the Stryker LFIT™ Anatomic CoCr
V40™ Femoral Heads discussed above could potentially result in: 1) User Annoyance; 2) Loss of Mobility; 3) Pain Requiring Revision; 4) Inflammatory Response; 5) Adverse Local Tissue Reaction; 6) Dislocation; 7) Joint Instability;
8) Revision to Alleviate Hazardous Situation; 9) Pain Associated with Implant Loosening; 10) Periprosthetic Fracture; and/or 11) Leg Length Discrepancy;
Has there been a Stryker LFIT Anatomic CoCr V40 Femoral Head voluntary recall?
Many Orthopedists believe Stryker may be very close to announcing a voluntary recall of the LFIT Anatomic CoCr V40 Femoral Heads, which would
come on the heels of higher than expected complaints related to the taper lock feature on certain catalog numbers of these Stryker Femoral Heads. So far, there has been no mandatory recall of the aforementioned large femoral heads
by the United States Food and Drug Administration (FDA) to Stryker. Patients implanted with these Stryker femoral heads may have suffered Stryker femoral head hip implant failure, Stryker femoral head hip implant disassociation,
Stryker femoral head trunnionosis and Stryker femoral head pseudotumors. Should Stryker Corporation officially declare a recall of these potentially dangerous femoral heads, and you have one of these femoral heads implanted in
your body, you may want to consider contacting a Stryker femoral head recall lawyer to determine if you may be entitled to compensation for any Stryker femoral head recall injuries.
What Stryker hip implant models are most commonly associated with the Stryker’s LFIT™ Anatomic CoCr V40™ Femoral Heads in question?
The Stryker LFIT™ Anatomic CoCr V40™ Femoral Head has been most closely associated with
use in conjunction with the Stryker Accolade TMZF (Titanium-Molybdenum-Zirconium-Ferrous), Stryker Accolade 2, Stryker Citation, and Stryker Meridian Hip Implant Stems. It is important to note that NONE of these Hip Implant Stems
have been recalled. Only specific catalog numbers of Stryker’s LFIT™ Anatomic CoCr V40™ Femoral Head have been part of a mandatory recall in Canada, and MAY BE part of a possible voluntary recall in the United States by Stryker
What are the specific catalog numbers of Stryker’s LFIT™ Anatomic CoCr V40™ Femoral Heads that may have been recalled?
HEAD DIAMETER (MM)
Do other hip implant models / femoral heads pose the same risk as the Stryker’s LFIT™ Anatomic CoCr V40™ Femoral Heads?
Between the years of 2006 and 2012, it is estimated that as many as 225,000 hip implants with
large femoral heads were implanted into patients. It is speculated that up to twenty different hip implant models from six different manufacturers (DePuy, Wright Medical, Smith & Nephew, Stryker, Zimmer and Biomet) may also
employ the use of large femoral heads