Australia’s Therapeutic Goods Admin. issued the new guidelines for patient follow-up, advising regular blood testing and soft tissue cross-sectional imaging for all ABG II patients, even in the absence of pain or swelling.
Orthopedic giant Stryker in July 2012 recalled its Rejuvenate Modular femoral stems and ABG II Modular necks, halting global production over concerns that the devices may be prone to "fretting and/or corrosion at or about the modular-neck junction," which may lead to pain, swelling and adverse reactions in surrounding tissue.
The original warnings recommended that physicians continue their usual routine for monitoring patients implanted with the hip implants in question, resorting to blood work and MRI or ultrasound scanning only if a patient reported pain or swelling that might be indicative of wear in the implant.
The new guidelines suggest regular blood testing and imaging for asymptomatic patients, repeat follow-up and evaluation and potential revision of the device if clinical analysis turns up evidence of metal debris in the blood.
Since the July advisory, Australian regulators have received reports that asymptomatic patients were identified with soft tissue injury and that at least 1 patient who developed symptoms shortly after initial evaluation turned out to have both heightened levels of metal ions in the blood as well as soft tissue damage, according to the warning.
Modular neck stems allow physicians to more accurately reproduce a patient’s natural hip geometry and "can facilitate femoral component insertion in more technically challenging surgical approaches," according to a Stryker report dated 2012.
However, the neck stems have also been associated with sensitivity arising from metal corrosion.
"Stryker Orthopaedics’ decision to voluntarily remove Rejuvenate and ABG II modular-neck stems and terminate global distribution of these products comes after continued post-market surveillance," according to a press release issued alongside the July 2012 recall. "The post-market surveillance data may be predictive of a trend."
The company later released a report considering the ongoing controversy over metal-on-metal hip implants, which sparked regulatory probes and public outcry after Johnson & Johnson (NYSE:JNJ) recalled hip systems made by its DePuy Orthopedics subsidiary over concerns that a higher-than-normal number of patients required surgeries to correct or remove defective implants.
The ABG II kerfuffle isn’t Stryker’s 1st metal-on-metal hip implant warning. In April the company contra-indicated its Accolade femoral stems against use with Mitch TRH acetabular cups and Mitch TRH modular heads manufactured by DePuy’s Finsbury Orthopaedics unit.