If you are the recipient of a DePuy hip implant device it is very important that you know which brand you were implanted with so you can be aware of the individual characteristics. Of course the primary difference between the ASR and its successor, the Pinnacle, is that the ASR was recalled in August, 2010, while the Pinnacle has not been recalled. The ASR and the Pinnacle are both metal-on-metal systems, designed to last from 10-15 years. Despite the fact that the Pinnacle is still being marketed and implanted, DePuy is facing scrutiny for the Pinnacle’s premature failures.
In fact, doctors who have tracked large numbers of patients with a DePuy Pinnacle hip implant believe that at least another ten percent will fail within the next 1-2 years in addition of the significant number which have already suffered failure. Although the final failure rate for the ASR has not yet been established a study released in March, 2012 by the British Orthopaedic Association indicated a failure rate of up to 49% after six years which is almost four times the rate DePuy admitted to at the time of the recall. A study of 1000 patients in the UK showed the Pinnacle had a failure rate of 8% at five years and 16% at 6 ½ years; it is believed the lower failure rate of the Pinnacle is due largely to the smaller head size.
A spokesperson for DePuy stated the company is closely monitoring the performance of the Pinnacle but remains confident in their product and will vigorously defend the Pinnacle against lawsuits. Despite this assertion, patients with a Pinnacle implant have experienced the same problems as those who were implanted with a recalled ASR including pain, swelling, limited mobility, dislocation and metal toxicity. Metallosis can cause a variety of issues including cardiovascular, neurological, renal, thyroid and gastrointestinal issues, loss of vision and hearing, memory loss, vertigo, DNA disruption, anxiety, depression and irritability and the formation of pseudo-tumors.
Perhaps the most significant design difference between the ASR and the Pinnacle is that the ASR incorporates a monoblock design and the Pinnacle’s design is considered a hybrid monobock, allowing the surgeon to fit the recipient with the properly sized acetabular cup and ball. The Pinnacle cup has an outer shell, while the ASR cup is made of a solid section of cobalt and chromium in a semi-hemispherical shape. The ASR cup is also thinner than normal, leading to misshapen cups and more wear and it is theorized that the cup is too shallow for the head, causing edge-loading when the ball hits the edge of the cup.
The design of the Pinnacle allows surgeons to choose from a polyethylene, ceramic or metal liner which fits inside the outer cup. When a metal trunnion liner is used, the Pinnacle, like the ASR, is likely to shed metal ion debris into the body leading to the potential of the patient developing metal toxicity. The Pinnacle hip implant fastens to the bone with screws, however the ASR simply allows the femur to grow into the device which could be responsible for the number of ASR cups which have loosened and failed. It is estimated there are over 11,000 ASR lawsuits currently pending with an additional 3,000 claims against the Pinnacle.