Hip replacement carries a degree of risk even in the best of situations. However, thousands of patient have had the risk of injury compounded by the use of dangerous “metal on metal” artificial hips.
I. The Problem of the Metal on Metal Design
In a metal on metal artifical hip, both the “ball and socket” of the hip joint are metal. In other words, the hip replacement femoral head (the ball) and acetabulum (the socket) are both metal. In comparison, other hip designs mate polyethylene-line acetabular cups to ceramic or metal femoral heads.
The following drawing shows a hip replacement. In the metal on metal hip, both the acetabular and the femoral head are metal.
Metal on metal implants present the following dangers:
- Loosening. The hardware becomes loose, and a revision surgery is necessary to remove the hardware and implant a new hip. This can be due to the design of the cup, which is shallower, so that there is an “edge loading”. In other words, the hip was not properly engineered to bear the weight and movement of a normal person. The metal on metal hip does not last longer than the prior hip designs, and it may have a short life. This is ironic since the manufacturers claimed increased longevity and the need for fewer, future revision surgeries.
- Illnesses from Metal Shards Released into the Body. The wear and tear of the metal grinding against metal releases metal shards and metal ions (cobalt and chromium) into the body. The may cause osteolysis (bone loss), metallosis (an accumulation of thick, gray fluid at the hip joint which can cause tissue death and bone degradation), and neurological problems (e.g., neadaches, persistent metallic taste in moth, memory loss, and cardiac issues).
II. Signs of Trouble
Generally, the first sign of trouble is extreme pain at the hip. A visit to the surgeon will be necessary.
However, some patients may not experience pain as an early symptom. Those patients should be monitored by both their orthopedist and internist. Patients should have thier cobalt and chromium levels in their blood tested regularly.
Of course, pain is a sign that the hip may be loosening or that the surrounding hip tissue is being attacked by metallosis.
III. Metal on Metal Hips
Here are some of the metal on metal hips causing injury:
- Zimmer Durom Acetabular Cup. This hip was recalled in 2008 voluntarily by Zimmer when it found its instructions inadequate for use and surgical implantation.
- DePuy ASR. The primary issues in the DePuy ASR hip device are loosening and metallosis. DePuy Orthopedics has a program to reimburse patients for expenses related to replacing the DePuy ASR, such as medical and lost income. Essentially, patients accepting the offer will release their claims for pain and suffering and future medical and lost income losses. Furthermore, DePuy will take-back the defective hardware after its removal, and this will prevent the patient’s attorney from getting the hardware inspected and evaluated by an expert. We strongly urge that patients do not accept this offer before reviewing it with an attorney.
- DePuy Pinnacle. Although the Pinnacle system mostly has ceramic on metal mating, Pinnacle did make metal on metal hardware. Cup loosening and metallosis are a problem.
- Wright Conserve. Wright Medical Technologies had a line of metal on metal implants.
If you or a family member has had a metal on metal hip implant, we recommend that you consult an attorney immediately. We seriously urge that you talk to an attorney if you have had a DePuy hip and if DePuy has made the offer of paying for a new hip implant. You should consult with an attorney before deciding on accepting DePuy’s offer. Please feel free to contact me for a free consultation at 800-581-1434 or write to firstname.lastname@example.org.
Mark E. Seitelman, 2/7/12, www.seitelman.com.