Smith & Nephew announced the voluntary recall in an “Urgent Field Safety Notice” to surgeons on November 15, 2016.
The recalled modular-neck component is used with the Modular SMF and Modular REDAPT hip stems, which are also being removed from the market. The implants were sold from October 2008 through July 2016.
Smith & Nephew said patients with modular-neck implants “may be at a greater risk of revision surgery” compared to patients with monolithic implants made out of a single piece of metal.
Complaints about metal-related side effects were reported in 0.5% of patients with the Modular SMF, and 0.25% of patients with the Modular REDAPT. Overall, most complaints were due to metal-related side effects, and the frequency was trending upward on a yearly basis.
Modular-neck hip implants have an interchangeable part between the femoral stem and the femoral head. This allows a surgeon to custom-fit the implant to each patient, but it also creates a “metal-on-metal” component. When the metal parts grind together, tiny particles of metal can break off and accumulate around the hip or leach into the bloodstream.
Smith & Nephew is not the first company to recall modular-neck hip implants. Stryker Orthopedics recalled the ABG II and Rejuvenate implants due to metal corrosion in 2012. Two years later, Stryker paid $1.4 billion to settle over 4,000 lawsuits for around $300,000 per case.
Cobalt/chromium metal-ion levels in the bloodstream exceeding 7 parts per billion (ppb) may indicate a soft-tissue reaction. This can be evaluated with an ultrasound or cross-sectional imaging scan.
Metal poisoning can cause pain, swelling, limited mobility, tissue death (necrosis), bone loss, and often requires revision surgery. Smith & Nephew does not recommend revision surgery for patients without symptoms. If patients do have blood metal-ion levels above 7 ppb, monitoring every 3 months might be considered.