The FDA Approval Process
The Stryker Rejuvenate Modular Hip was submitted to the FDA for approval to market on April 4, 2008 and was approved on June 3, 2008 as a Special 510(k) submission for a line extension of the Stryker Modular Hip System, approved for market on September 13, 2007.
The Stryker Rejuvenate line extended the combined head/neck length options for the Rejuvenate and was intended for use with any currently available Howmedica Osteonics acetabular components, V40 femoral heads (CoCr), C-Taper Alumina heads (ceramic) when used with the V40/C-Taper Adaptor and the Biolox Delta (ceramic) Universal Taper Heads and Sleeves. Stryker received marketing approval for a size extension of the Rejuvenate line on October 20, 2009 for additional combined head/neck length options.
The Stryker Modular Hip was the first modular design made by the company. It was approved for market based on substantial similarity to Wright Medical Technology’s Profemur Total Hip Modular Neck System.
The present invention provides a modular hip prosthesis, and instrumentation for implanting the same, which has provision for varying the angulation between the stem portion and the trochanteral module portion by provision of connection means between the neck and stem which can be positioned or attached together in a variety of rotational positions. Variation of the angulation or anteversion is made possible in accordance with the present invention by virtue of the fact that the axis of the connection portion of the stem and neck is angularly offset from the axis of the body of the stem and neck, respectively. A further aspect of this invention is the provision of instrumentation for formation of a cavity for implantation of a prosthesis of this invention which is provided with indication means for indicating to the surgeon the optimum angle for assembly of the prosthesis of invention for implantation into a particular proximal femur.
The initial material used was Titanium (Ti) and it was approved for use with a Cobalt Chromium (CoCr) head. Predictably, the Wright Pro-Femur has been plagued with problems including fretting (deterioration) corrosion resulting in fractures. There are several lawsuits against Wright related to the Pro-Femur alleging hundreds of reports of modular neck fractures due to corrosion of the Ti neck with a failure rate of 11.2 percent. Because of this problem, the Wright Pro-Femur material was changed from Titanium to CoCr in 2009. In 2010, problems remained and the Pro-Femur was then cleared to be used with ceramic heads.
System Clinical Study
As part of its 510(k) approval, Stryker initiated a prospective clinical study in November 2010, Rejuvenate Modular Outcomes Study. Subjects will be evaluated for freedom of hip revision at 5 years and clinical outcomes for up to 10 years after surgery. The outcomes of this study are not yet available.
Stryker Urgent Field Safety Notice Regarding Rejuvenate
In response to the problems noted in the MAUDE data, Stryker issued an Urgent Field Safety Notice for Corrective Action for its Rejuvenate Modular Stems and Necks in April 2012.
According to Stryker:
“This communication is intended to inform implanting and/or treating surgeons and other healthcare professionals that Stryker has updated the Instructions for Use (IFU) for the ABGII Modular and Rejuvenate Modular Hip Systems. This is based on a reported rate of less than one percent for revisions potentially associated with fretting and/or corrosion at of about the modular neck junction.”
The Safety Alert defines the potential hazards as the following:
- Excessive metal debris and/or ion generation. Deterioration and/or corrosion at or about the modular neck junction may lead to increased metal ion generation in the surrounding joint space.
- Contact between metal ions and tissues and structures during an implant’s service life may result in an Adverse Local Tissue Reaction (ALTR), the inflammation of associated tissues experiencing immunological response (metallosis, necrosis, and/or pain).
- An ALTR may result in the need for revision surgery.
- Patients with a heightened sensitivity to these ions may experience a hypersensitivity/allergic reaction which may result in the need for revision surgery.
- Excessive fretting (deterioration) debris. Fretting may lead to increased metal debris in the joint space (concentration of debris exceeds individual patient threshold) resulting in osteolysis. Osteolysis may be asymptomatic and may result in the need for revision surgery.
Through this Safety Notice, Stryker attempted to shift the blame away from their product and place the blame directly on the patient and the surgeon. The Safety Alert documents the factors which may increase the risk of the above potential hazards as follows:
- Additional femoral offset: This may result in greater relative motion between the neck and stem at the taper junction.
- Solution Chemistry: The local chemistry around an implant may vary considerably from patient to patient. Factors such as diabetes and infection may play a role in potential corrosion of an implant as these conditions may affect the pH of the tissue surrounding the implant. Local pH levels may also influence corrosion.
- Additional weight or excessive patient weight.
- Inadequate locking or assembly of the tapers may lead to increased mechanically assisted corrosion.
- Inadequate cleaning of the neck taper may lead to increased debris generation.
- Modular Junctions: Mate modular components firmly to prevent dissociation. Machined taper surfaces must be clean, dry and firmly mated to ensure proper seating and assembly. Repeated assembly/disassembly or failure to clean, dry and firmly mate the components could compromise the taper lock and potentially lead to fretting/corrosion.
According to the United States Food and Drug Administration, Stryker Orthopaedics has issued a voluntary recall of their Stryker Rejuvenate and ABG II modular-neck stems. The attorneys at Searcy Denney have begun filing Stryker lawsuits pursuing compensation on behalf of clients across the country who have suffered injuries as a result of using Stryker Rejuvenate hip systems.