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Hips and Hip Replacements: What you need to know

by Thomas W. Miller Ph.D. ABPP, Staff Writer

A Closer look at Hip Surgery

We as humans are tough on our hips. Throughout our lives we are twisting and turning, running and walking, and in the world of athletics our hips and knees and ankles are called upon in baseball, football, basketball and ice hockey to support and balance us over time. And it is over time that we gradually wear and tear on such body parts through arthritics and other forms of inflammation. The hip is one of the body’s largest weight-bearing joints. It consists of two main parts: a ball (femoral head) at the top of the thighbone (femur) that fits into a rounded socket (acetabulum) in the pelvis. Bands of tissue called ligaments (hip capsule) connect the ball to the socket and provide stability to the joint.

The U.S. Food and Drug Administration (FDA) recently posted a public health communication about metal-on-metal hip components used in total hip arthroplasty (THA). The American Academy of Orthopedic Surgeons (AAOS) appreciates this thorough and wellconsidered look at the concerns surrounding the use of these implants. The FDA’s communication also keeps each of the key stakeholders in mind: patients, potential patients, orthopedic surgeons and other medical practitioners. With the patient’s safety, health, and quality of life always in mind, the members of the AAOS will continue to work with device makers and agencies such as the FDA to share knowledge and communicate any potential concerns.

What is the role of the Food and Drug Administration?

The FDA is a partner in patient safety and education. The FDA notes that a significant majority of metalon- metal hip replacement implants have successfully relieved pain and improved function without any problems for the patients whom have received them but there have been some concerning exceptions. They are working together to investigate and report these concerns and will continue to communicate with our 36,000 members, the medical community and the public.

What is involved in hip replacement?

Once you and your orthopedic surgeon have discussed and determined you are a candidate for hip replacement surgery, he or she will select a hip replacement device for you based on your body structure, medical history, and lifestyle. By replacing your diseased hip joint with an artificial joint, hip replacement surgery can relieve your pain, increase motion, and help you get back to enjoying many normal, everyday activities.

What materials are involved in hip replacement systems?

Replacement joints are made of many different materials — metal, plastic, and ceramic are the three classes of materials used. Sometimes, the socket is made of a different material than the ball, or is lined with a different material, and sometimes the ball and socket are made of the same material. The orthopedic surgeon will recommend the best combination to the patient. In February 2011, the FDA issued a public health communication about hip replacement components that have both a metal ball and a metal socket (metal-on-metal hip devices). You may read in detail their notification at: Federal Drug Administration Communication http://www. fda.gov/MedicalDevices/ ProductsandMedicalProcedures/ ImplantsandProsthetics/ MetalonMetalHipImplants/default. htm

What do we need to know about metal on metal devices?

Metal-on-metal (MoM) hip devices consist of a ball, stem and shell, all made of metal parts. A surveillance study monitors adverse events after a device has been approved or cleared by the FDA.

Manufacturers of MoM hip implants have orders from the FDA to further study the safety of metal-on-metal devicessafety of metal-on-metal devices (http:// www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ ImplantsandProsthetics/ MetalonMetalHipImplants/ ucm241769.htm).

As a result, if you have a MoM hip replacement device, your surgeon may be contacting you to find out how you and your device are functioning.

If after a joint replacement surgery you experience pain or have other, new medical concerns or issues, please talk to your doctor or orthopedic surgeon.

Although the vast majority of patients have not had any problems with MoM implants, orthopedic surgeons and the FDA are concerned because a few cases reported in the peer-reviewed literature and through a British database have involved patients who had local hip symptoms (pain and swelling) as well as other medical concerns seemingly unrelated to the hip.

If, after a joint replacement surgery, the patient experiences pain or have other, new medical concerns or issues, they are encouraged to contact their primary care physician and orthopedic surgeon about these concerns.

How do I know if I have a metal-on-metal hip system?

Patients are usually told about the type of implant they are receiving prior to the surgery. If you are uncertain about which type you have, you should contact the orthopedic surgeon who performed your procedure.

How often should I follow-up with my orthopedic surgeon?

Based on your individual circumstances, your orthopedic surgeon will determine how frequently you need to follow-up. There are some cases where your orthopedic surgeon may recommend more frequent followup based on the type of hip implant, the outcome of the surgery and your recovery, and the results of blood tests or imaging procedures. If you develop new or significantly worsening symptoms or problems with your hip, including pain, swelling, numbness and/or a change in ability to walk, contact your orthopedic surgeon right away.

What should I discuss with my orthopedic surgeon at each follow-up appointment?

It is critical that you talk to your surgeon about any new or worsening symptoms related to your hip, groin, or legs since your last visit. This may include pain, swelling, numbness, and change in ability to walk. It is also important that you discuss any changes in your general health. Whether you are being seen or treated by another physician for a new condition since receiving your metal-on-metal hip implant.

What symptoms might a metalon- metal hip implant cause?

Symptoms may include hip/groin pain, local swelling, numbness or changes in your ability to walk. There are many reasons a patient with a metal-on-metal hip implant may experience such symptoms and it is important that you contact your surgeon to help determine why you are having them.

Are there other medical effects that can occur with my metal-on-metal hip implant system?

Metal-on-metal hip implants, like other types of hip implants, are known to have adverse events, including infection and joint dislocation. There is some case reports of the metal particles causing a reaction around the joint, leading to deterioration of the tissue around the joint, loosening of the implant, and failure of the device, as well as some of the symptoms described above.

In addition, some metal ions from the implant may enter into the blood stream. There have been a few recent case reports of patients with metalon- metal hip implants developing a reaction to these ions and experiencing medical problems that might have been related to their implants, including effects on the nervous system, heart, and thyroid gland. As with any and all changes, it is important to contact your primary care physician and contact your surgeon to help determine why you are having these symptoms and concerns.

Sources through Websites for the following links:

The American Academy of Orthopedic Surgeons: Questions and Answers about Metal-on-Metal Hip Implants

The American Academy of Orthopedic Surgeons: Hip Implants

American Association of Hip and Knee Surgeons: Information about hip and knee replacement for patients American Association of Hip and Knee Surgeons: Pre Op Surgery Center Patient Education: Hip Replacement Surgery

Federal Drug Administration Communication (http://www.fda. gov/MedicalDevices/ ProductsandMedicalProcedures/ ImplantsandProsthetics/ MetalonMetalHipImplants/default. htm)

NIH Consensus Statement on Hip Replacement

About the Author

Thomas W. Miller Ph.D. ABPP, Staff Writer, Sampler Publications
See other stories by Thomas W. Miller Ph.D. ABPP, Staff Writer

Thomas W. Miller, Ph.D. ABPP is a Professor Emeritus and Senior Research Scientist, Center for Health, Intervention and Prevention, University of Connecticut and retired service chief from the VA Medical Center and tenured Professor in the Department of Psychiatry, College of Medicine, University of Kentucky.

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