Management of Pseudo-Tumors in Stryker Rejuvenate Hip Implant Recipients—Part Two

Artificial hip implantation has become increasingly common, particularly for younger, active patients who have suffered significant osteoarthritis in their hips. While the five-year survival rate following hip replacement is above 95 percent, recent device failures, implant recalls and instances of chromium and cobalt toxicity as well as other, serious hip implant problems have plagued the artificial hip industry. The number of pseudotumors occurring in those with artificial hips is increasing, particularly in all-metal implants or designs which implement metal neck junctures and metal trunnions such as the StrykerRejuvenate.

Although pseudotumors are not cancerous and do not indicate infection, they can nonetheless be quite serious, causing local tissue destruction. In many cases revision surgery will be necessary during the removal of the pseudotumor. Both the Rejuvenate and the ABG II were part of the Stryker hip replacement recall in July of 2012 due to fretting, corrosion, implant failure and metal poisoning. When the implant is subject to corrosion, microscopic shards of metals are released into the hip tissues as well as the bloodstream. In addition to contributing to the formation of pseudotumors, this metal debris can cause inflammation, chronic pain, tissue necrosis, bone loss and symptoms of metal toxicity such as:

·         Gastrointestinal disorders

·         Neurological problems

·         Cardiovascular, renal and thyroid issues

·         Loss of vision and hearing

·         Balance problems and memory loss

·         Depression, anxiety and irritability

·         Disruption of DNA

One study sought to establish the relationship between levels of metal ions and presence of pseudotumors in patients with metal hip implants. An overall prevalence of asymptomatic pseudotumors of 4-5 percent among those with metal or partial metal hip implant was noted—higher than previously believed. Pseudotumors were found to be more common in women, and patients with pseudotumors were found to have significantly higher levels of cobalt and chromium in their blood and joint fluid. It appears that pseudotumors could well be a reaction to metal debris generated by such hip implants as the Stryker Rejuvenate as well as other metal hip implant devices. Patients with unusual hypersensitivity to metals were also found to have a higher risk of developing pseudotumors.

One doctor investigated the source of wear in the removed implants among patients with pseudotumors as compared to implants removed for other reasons. Implants which were replaced due to the presence of pseudotumors showed much greater wear on the femoral and acetabular cup components. When femoral components come into contact with the edge of the acetabular component, edge loading occurred and in this study the wear on the acetabular cup was always on the edge.  The patients with pseudotumors often experienced edge-loading during walking or other activities while less than one in four patients without pseudotumors experienced edge-loading. 

Surgeons are cautioned to be alert for the presence of pseudotumors in hip implant recipients even when x-rays appear normal. Special care should be taken when positioning hip implant devices in smaller women in order to avoid the occurrence of pseudotumors, and patients should have regular reassessments. Patients with metal sensitivities should reconsider implantation with an all-metal or partial metal device in favor of a ceramic or polyethylene implant. Any unusual pain or swelling requires an appointment with a physician and possible revision surgery depending on the size and location of the pseudotumor as well as whether tissue damage has occurred.