4/4/2023

A recent serious supply chain problem has forced me to rethink my exclusive use of Zimmer-Biomet Recap/Magnum hip resurfacing implants. There are currently only three implants available in the US. Ceramic-ceramic trials are underway in Europe and Metal/polyethylene designs are on the drawing boards of several companies. These will likely take years to come to market.

Available implants:

1. Zimmer-Biomet ReCap/Magnum (RM) metal-on-metal (MoM). FDA-approved implants used in an off-label fashion by me and others for hip resurfacing. Both components are porous for bone in growth. All sizes are available. No restrictions for women. Most data available is my personal data. A few other surgeons in the US use these occasionally. It is not available outside the US. I designed these but no longer receive royalties. I have been using this since 2007 and my data is published on my website as well as in peer-reviewed scientific journals.
2. Smith-Nephew Birmingham Hip Resurfacing (BHR) MoM. FDA approved for the indication of hip resurfacing. Available worldwide. The femoral component is cemented, and the acetabular is porous for bone ingrowth. Most used resurfacing implant by far with extensive data from many centers supporting its use. Smaller sizes below 48mm have been withdrawn from the market. The label has been amended to exclude women.
3. Synovo Preserve ceramicized metal/polyethylene boutique implant is only available to Jim Pritchett. Both components are porous for bone ingrowth. FDA status is not known to me. All sizes are available. No restrictions in women. All data is by Jim Pritchett

Both the RM and the BHR are MoM-bearing devices; the differences lie in the fixation on the femoral and acetabular components and the style of instrumentation to implant them. The RM is a fully uncemented bone ingrowth implant system. The BHR employs cement fixation on the femur and uncemented on the socket. My bias has been for uncemented fixation on the femur, but after 10 years, the cemented BHR femoral implant has held up much better than I had predicted. I cemented about 1000 resurfacings before I switched to uncemented in 2007. We now know that cement does as well as uncemented on the femoral component in men with osteoarthritis, but there are 2 subgroups of patients in which cement performs poorly when the diagnosis is osteonecrosis or in older women with osteoporosis. In both of these situations too much cement tends to infiltrate the head and the exothermic cement process damages the remaining head too much. If you are a man with osteoarthritis and good bone, a BHR and Recap/Magnum have similar outcomes at 10 years with less than 1% failures if done by expert surgeons (>1000 cases). Both far surpass THR durability.

Although both systems employ porous bone in growth sockets, they are made differently. The BHR has a cast-in cobalt porous surface covered with hydroxylapatite (HA). Magnum has a porous titanium layer plasma sprayed onto the cobalt-chrome cast implant. This surface could debond from the substrate implant resulting in loosening. This has happened once so far in >6500 Magnum cases with follow-ups up to 18 years. Therefore, at the 10-year mark, there is no measurable difference between the two methods. But what about extremely long-term outcomes? We have no data beyond 20 years. So, we can only speculate. Theoretically, I believe that the Recap uncemented femur will last longer than the BHR cemented femur. On the other hand, I believe the BHR acetabular component with a cast-in porous coating will likely outlast the Magnum porous titanium coating that is bonded to the cobalt chrome implant. So which implant will win in the long term? Hard to know.

In my opinion, men with osteoarthritis and reasonably good bone and implant bearing sizes > 48mm (90% of men) can flip a coin. BHR and Recap/Magnum are equivalent at 10 years and longer-term outcomes are not known. If off-label use is a problem for you, you can choose a BHR.

Women have only one choice, Recap/Magnum. The BHR is not sold in the sizes that most women require and even in the few women with larger bearing sizes, the BHR labeling makes it legally too risky for me to offer these to women in our overly litigious society. If off-label use is a concern for you, then the Zimmer/Biomet Recap/Magnum is not the implant for you. You can investigate the FDA status of the fully porous ceramicized metal/polyethylene option available with Jim Pritchett in Seattle. But I do not know the FDA status of his implant. The only other option is a standard stemmed total hip which has considerably inferior outcomes in my opinion.

I am the primary design surgeon for the Recap/Magnum and am therefore biased. However, I have not received any royalty payment for this implant for many years. Most of my published data is with the Recap/Magnum and it is my preference for three reasons. I have shown the world’s best durability outcomes for any hip surgery with a 99% 16-year implant survivorship in all patients regardless of age, sex, or diagnosis. The instruments are designed by me for my personal style of surgery. I normally have all sizes and can use them for any patient that I choose. Patients have to decide if FDA approval for my use is important for them.

Although the Recap/Magnum implants are FDA-approved, they do not have an “indication” to be used together for hip resurfacing. This means that Zimmer Biomet may sell the implants to any surgeon but cannot promote them for hip resurfacing use. The FDA has no jurisdiction over surgeons. I can use any FDA-approved implants for any use that I see fit. I do not have to stick to the approved indications. It is perfectly legal and a part of regular medical practice. There is not even any requirement to inform patients about off-label use. I do inform patients because MoM hip resurfacing is so controversial. However, my data strongly supports this use, and I provide this data on my website. You can make an informed decision.

Zimmer/Biomet, the largest orthopedic implant company in the world has been struggling with supply chain problems over the last year. In the last month, it has gotten so bad that we ran out of all of the larger Recap implant sizes typically used for men (>48mm). The smaller women's sizes are currently still available. I have had to convert some men to the BHR and cancel some others. The problem persists and we are not sure when it will be resolved. Multiple delivery dates have been missed. ZB top brass has assured me that they are committed to solving this problem and will eventually resume a full supply to me and other surgeons requesting the uncemented Recap. Smith Nephew who makes the BHR metal-on-metal (MoM) implant also has a supply problem and has limited sales to other countries where the sales price is lower. They offer resurfacing in bearing sizes 48-56.

Men requiring sizes 48-56 can opt to switch to a BHR or choose to wait until the ZB supply chain is sorted out. Women requiring larger sizes (10%) have no choice but to wait. This may take a few months. Also, I am fully booked until August. Therefore, rescheduling large numbers of patients will be a logistics nightmare. However, I am committed to working extra days, even Saturdays, if possible, to get everyone rescheduled who wants to wait for ZB implants. Let me emphasize that I have no control over the ZB supply chain. I think ZB is committed to solving the problem. However, there are many FDA regulations that make any changes at an implant company very difficult. Their hands are really tied by over-regulation. I don’t know how long this will go on.

My question to you is:

Do you want to keep your surgical date and switch to a BHR, or do you want to be delayed 1-2 months hoping for the supply chain problem at ZB to be resolved?

You can let Crystal Spires know your decision or request that I call you if you have further questions.

Thomas Gross

CONTACTS:

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