Metasul®
The strength of metal-on-metal
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Developed and refined in Europe for over 40 years, Metasul has helped over 140,000 patients worldwide. In 1988, after rigorous testing at 15 independent clinical sites in the United States, Metasul was cleared for use in the United States. In the Metasul implant, the conventional plastic polyethylene insert has a cobalt chrome metal inlay. This helps minimize wear over time, potentially increasing the longevity of the implant. |
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Patient Questions and Answers
Lawrence D. Dorr, M.D.
Medical Director
Bone & Joint Institute at Good Samaritan Hospital
Los Angeles, CA
The information herein is based upon information provided by Lawrence D. Dorr, MD, and is provided for informational purposes only. It is not intended to replace consultation with your personal physician. It is very important that you discuss with your doctor any questions or concerns that you may have regarding the procedure you are considering.
1. How is Metasul different from regular hip surgery?
The operation with the use of Metasul is performed exactly the same as any total hip replacement. The risks and benefits for the patients are the same, except for any specific risks from the metal-on-metal articulation surface which are subsequently discussed. Total Hip Replacement (THR) is a substitution for lost cartilage. Traditionally, the bearing surface has been a metal ball rubbing against a plastic cup (the acetabulum, or "socket."). With the use of modular hip replacements these are exchangeable surfaces. Therefore, the only difference from regular hip surgery is that the plastic cup also has a metal inlay. This is implanted in the regular fashion. These metal-on-metal surfaces are also exchangeable in the future if necessary.
2. Is Metasul good for any age? For what type of patient is it best suited?
Metasul is suitable for a patient of any age. It is best suited for a patient who is active regardless of age. Active patients have the highest incidence and amount of wear. The Metasul surface is being used to reduce wear, which may subsequently will reduce osteolysis and potentially prolong the life of the hip replacement. Because the traditional metal on plastic hip replacement has had a life expectancy of 10+ years, any patient with life expectancy greater than that is a candidate for Metasul surfaces.
3. Can I have a Metasul hip if I am allergic to metal? Are there any other conditions that would disqualify a patient from Metasul?
A patient should not have a Metasul hip if he/she is allergic to cobalt, chrome, molybdenum or nickel. Skin testing by an allergist should be performed if there is any suspicion of an allergy to these metals.
If a patient has metal allergies just to copper or steel (iron), then Metasul could be used. Metal is used with almost every hip replacement. If a patient is allergic to metal, the choice for hip replacement must be altered accordingly, including the femoral stem and the use of a metal acetabular cup. Therefore, metal allergy is not a problem specific for Metasul use.
4. How long will a Metasul hip last?
Metasul offers the possibility for much greater longevity because the amount of wear particles produced with Metasul is up to 40 times less than with the traditional hip replacement. The longevity of a Metasul hip will depend on the quality of the surgery performed, and the patient’s weight and particularly the activity level.
5. Will the Metasul hip be detected in a metal detector?
Maybe. Not all total hip replacements or knee replacements are detected in metal detectors, depending on the sensitivity of the metal detector. Just the addition of a Metasul bearing surface to the metal of the normal total hip replacement should not change this.
6. How long after surgery before I feel good?
The use of a Metasul bearing surface does not change the healing process. As discussed above, this is simply a different bearing surface. The healing process is determined by the bone preparation that is done at the time of surgery. This bone preparation does require injury of bone, and bone takes months to heal. This is the primary determinant of the postoperative course. In general, all patients have three phases of rehabilitation after surgery.
The first six weeks are the time when the energy of the patient is lowest, the muscles are weakest and the pain is greatest.
Between 6 weeks and 4 months, the patient is gradually improving in leg strength and the discomfort is decreasing because the bone and muscles are progressing in their healing. The patient may limp as long as there is muscle and bone healing. The amount of limp will also be related to the preoperative condition of the patient and to the activity of the patient during this 3-4 month period. Too much activity will result in higher level of pain and limp.
The third phase of rehabilitation occurs between four months and one year when the patient gains maximum strength and assumes the pain relief to be gained from the surgery. It must be recognized by all patients that 35% of the normal population over the age of 50 complain of some discomfort with their hip and knee even without a total hip replacement. It is therefore not unexpected that one-third of patients with total hip replacement will have some aches and pains following total hip replacement, whether or not Metasul is used.
7. What activities can I do and cannot do after getting a Metasul hip?
The limitation in activities after a hip replacement using Metasul are not different than any other hip replacement. The limitations are avoidance of high impact activities. These would include sporting activities that require running such as jogging, basketball, racquetball and jumping activities such as volleyball or gymnastics, etc. Sporting activities that can be done include golf, doubles-tennis, skiing, walking, gym exercises, including leg machines with light resistance and more repetitions, swimming, and bicycling.
8. In recovering from surgery, are there special exercises I need to do with a Metasul hip that are different from exercises after other hip replacements?
The exercises after Metasul hip replacements are not different. The best exercise in the first three months is walking so that the leg muscles can regain their normal use (walking is the reason that we have legs!). Most importantly, it is in the first three months that the activity level is significantly reduced to allow healing of the bone and muscles, as discussed above. There are not rigid guidelines for activity levels because patients differ. The patient and his/her physician must determine the activity level that provides comfort and not exceed that. In my estimation, formal physical therapy is not necessary after a hip replacement if patients are willing to walk and do a few simple exercises at home.
9. There are questions raised about the risk of cancer with a metal-on-metal hip implants. Does Metasul increase my risk for cancer because of the ions produced?
There is no identified increased risk of cancer with a metal-on-metal articulation that was used in the past, nor has there been any identified with Metasul. Metal-on-metal articulations were commonly used in the 1960s and early 1970s. Some of these patients have maintained their hip replacements for 20-30 years and there have been no reports in the literature of any definitive relationship to cancer. There have been epidemiological studies performed that do not find any increased risk for cancer. This is a theoretical concern that is most commonly used as a commercial argument against Metasul by companies that do not have the product.
10. There are reports that metal-on-metal hips "click" or squeak." Does Metasul click or squeak?
I have had no experience with any patient having a hip that squeaks. I have one patient who had a click for one year that eventually resolved. However, I have had patients who have a click feeling with metal-on-plastic hips also. There are no reports in the literature in the theories published of patients having a complication listed as clicking or squeaking. There have been anecdotal reports of squeaking hips, but I have no personal experience, nor is there any documentation.
Voted one of the Best Doctors in America in 1992 by Neifeh and Smith, Dr. Dorr has played a significant role in developing state-of-the-art orthopedic procedures and implants. He is currently participating in the clinical investigation of Metasul, a metal-on-metal hip replacement.
Dr. Dorr previously served as Professor and Director at USC Center for Arthritis & Joint Implant Surgery at the University of Southern California, Los Angeles. He is published in various national and international medical journals including Journal of Bone & Joint Surgery, Clinical Orthopedics , Journal of Arthroplasty and Contemporary Orthopedics. He has presented to numerous conferences and seminars internationally including his "State of the Art in Hip and Knee Replacement" program.
Dr. Dorr is a graduate of University of Iowa Medical School (1967), completed his residency in orthopedics at the USC Medical Center (1976) with military service in the United States Navy as a Lieutenant Commander, Medical Corps, Jacksonville, FL (1968-1971).
