Metal-on-metal total hip arthroplasty (THA) surgeries have recently been associated with the formation of cysts and severe limb swelling, new adverse reactions to the already controversial devices.
As we’ve long written, research has linked metal-on-metal hip implant devices to a growing array of adverse events that include tissue necrosis, pain at the implant site that sometimes spreads to the groin and back, inflammation, swelling, metal poisoning, high failure rates, osteolysis (bone loss), and fluid collection/solid masses around the hip joint.
An emerging study, published in the Orthopedics Journal, involved a case of a 54-year-old female patient who developed an iliopsoas bursal cyst, which led to venous obstruction and significant swelling in her lower limbs. She also suffered from a high level of chromium and cobalt ions and the study’s authors indicated that the woman’s condition was, in fact, the result of metallosis. The metallosis occurred due to the so-called “edge loading,” related to the device’s cup liner, which is a component of the metal-on-metal device. In this case, the patient was implanted with a DePuy Pinnacle hip implant constructed with an Ultamet Liner.
Five years after the woman was implanted with the DePuy Pinnacle hip implant, she began to experience limb swelling that worsened with ambulation, which was caused by vein obstruction. According to the study’s authors, the woman underwent revision surgery to remove the metal-on-metal implant and be re-implanted with a ceramic-on-ceramic bearing interface. The patient also underwent drainage of the bursal cyst, and removal of inflamed joint tissue (synovectomy).
These cysts can present as either pain or a groin mass, according to the researchers. Also, vein compression and limb swelling have been seen in metal-on-polyethylene THA devices related to these types of bursal lesions, as well as a result of pseudotumors with metal-on-metal resurfacing devices. Cyst treatment typically requires removal of the metal debris source, in this case, the metal-on-metal hip device, the study authors explained. Generally, this is accomplished by revision surgery to a nonmetal-on-metal bearing interface as well as drainage of the cyst and removal of damaged tissue and foreign objects (debridement).
The findings likely have significant implications for the risks to which metal-on-metal hip implant patients are exposed. DePuy Orthopaedics, a unit of Johnson & Johnson, recalled its ASR hip device and is also the maker of the Pinnacle. Biomet, is the maker of the M2a Magnum™; Smith & Nephew, makes the Oxinium™ and the Birmingham BHR; Zimmer is the maker of Durom; and Wright Medical Technology makes CONSERVE® Hip systems and the PROFEMUR®.
Metal-on-metal hip devices made headlines in August 2010 when DePuy recalled 93,000 of its devices worldwide over high failure rates. Studies have since revealed that the failure rates seen with the DePuy device were neither brand nor manufacturer specific and were, rather, unique to the entire class of device. Researchers now believe that metal-on-metal implants shed ions when the implants’ surfaces articulate, or rub against each other, which may lead to a number of adverse reactions.
