11/22/2024

Alternatives for hip resurfacing

The era of the Biomet Recap/Magnum has come to an end. Zimmer has stopped manufacturing this implant. After nearly 20 years of using this implant for hip resurfacing and posting the best long-term durability outcomes for any type of hip surgery, I will have to change. To continue performing hip resurfacing for all patients is becoming more challenging because of Zimmer's unfortunate decision.

I will offer the BHR (Birmingham hip resurfacing) to men with good bone. Shorter men have a higher chance of needing a smaller implant (not available) and will sometimes get a backup total hip replacement (THR). Women and shorter men can choose to enroll in the Polymotion Hip Resurfacing study and receive this implant.

Certain patients with poor bone quality will no longer be candidates for hip resurfacing because both of the currently available implants feature cemented femoral components which have an excellent track record with good bone, but a higher failure rate in patients with osteoporosis or bone defects.

Other implants are in the development pipeline, but only limited options are currently available.

The BHR has been available for many years and has an excellent track record. It is an excellent choice for men who require a bearing size greater than 48mm. This is a hybrid metal-on-metal (MoM) implant. This means the femoral component is cemented and the socket is uncemented. Women cannot be done because the manufacturer (Smith Nephew) advises against it. I disagree with their opinion, but ignoring their instructions would pose too great a legal risk in our overly litigious society and its broken legal system. Also, the smaller sizes below 48mm that are usually required in women are just not made anymore. Women are just out of luck because of the decisions made by the men who run Zimmer and Smith Nephew and our broken legal system. Implant size is most related to patient height, therefore shorter men are also unable to get resurfacing. But in men with osteoarthritis (OA), the 10-15 year published outcomes by a select group of expert surgeons who have a similar skill level as I do have similar outcomes with the BHR implant that I have with the Recap/Magnum. I do not hesitate to offer this as an excellent alternative.

The Polymotion hip resurfacing by JointMedica and Exactech will be available as part of an FDA IDE trial beginning in February 2025. It is a hybrid implant with a cobalt chrome cemented femoral component and an uncemented vitamin E crosslinked polyethylene (VE XLPE) socket with a titanium porous coating. All sizes will be available. There will be some study restrictions. No patients over 64, no AVN, no severe dysplasia, no osteoporosis, no large femoral or socket bone defects. Also, this study will be conducted exclusively at our surgery center. Therefore, patients who require a hospital environment do not qualify. These are all patient groups that I previously did with the Recap/Magnum but can no longer offer resurfacing to. This represents less than 5% of cases. Only a small number of implants will be available for this study starting in February and ending a few months later when we have used up our implant allotment.

Zimmer has never been a friend of metal-on-metal resurfacing after their poor experience with the Durom implant. When Zimmer acquired Biomet 8 years ago, I suspected that they would kill Recap/Magnum. Fortunately, we got another 8 years of using this implant and I am now publishing the best long-term outcomes of any type of hip surgery with uncemented Recap Magnum. It is hard to believe that Zimmer would discontinue manufacturing the implant that has the best success rate of any implant ever made by Zimmer (or any other company). But there are similar long-term outcomes published with the BHR resurfacing implant in men.

The problem is that the company (Smith Nephew) discontinued the smaller sizes and placed a restriction on using it for women because of the problem of metallosis that used to be more common in these situations. As you can read elsewhere on my website, I solved this problem of metallosis over 10 years ago by discovering a safe zone for placing these implants. This safe zone has been validated in thousands of patients. I still have not had any failures due to metallosis since 2009 in over 4000 consecutive cases. The BHR is safe in smaller sizes and women as long as you place the cup in the safe zone. For various reasons, the company is unwilling to reinstitute smaller sizes, remove the restriction on women, or develop an uncemented femoral component.

In summary, I will be using the BHR in men. At this point, there is still an unlimited supply of this implant system. Based on your height I can give you the odds that your hip will be too small for a BHR. However, the final decision will be made based on the actual measurement of your head size during the operation. If your head size is much smaller than 48mm I will not have the necessary implant in the BHR system and I will use an uncemented dual mobility THR as a backup. This has similar stability as hip resurfacing, but the THR stem will likely limit vigorous impact activity and heavy work and it will not last as long.

In women, the only US option is to have a Polymotion resurfacing. For full details see my position paper on this topic. This is a new implant that will be available as part of an FDA IDE study. All implant sizes are available. The costs for the procedure will remain the same as before. There will be an added requirement that you follow up in person here in Columbia at 4 intervals from surgery: 6 weeks, 6 months, 1 year, and 2 years. You will be contractually obligated to do this in writing. If you fail to show up, you endanger the study and subsequent implant approval. This will harm thousands of future patients who will not be able to have a resurfacing and will be condemned to a second-rate THR. Because of the cost of running an FDA study only a limited number of these will be available. Full approval which allows unlimited supply will likely occur in 2029.

Other implants are available in Europe. Dr Koen DeSmet in Ghent Belgium is conducting a trial of the hybrid ceramic on ceramic Resurf implant made by MatOrtho. Excellent early 2-year data has been published. Also, Prof Justin Cobb in London has just received European approval for his ceramic-on-ceramic uncemented H1 Embody implant. There is as of yet no publication of his data. Neither of these implants is available yet in the US. Both companies will most likely also need to undertake lengthy and costly FDA IDE trials to get approval to sell in the US. I will likely be involved in at least one of these.

With the very unfortunate withdrawal of the Recap/Magnum from the market by Zimmer, we have lost the implant with the best long-term implant survivorship data and the most versatility to address the most complete range of patient cases. No THR can come close to the functional and durability outcomes of hip resurfacing. The next best implant, which also has the most extensive data to back it up is the BHR, but this can only be used in limited patient types. Finally, Polymotion is a very promising new implant but has only short-term data to back it up. This is the only option for women and smaller men in the US.

You might ask, "If Dr Gross can no longer use the Recap/Magnum with which he has published the best outcomes for hip resurfacing in the world, and my next best option is the BHR, why not go to someone more experienced with the BHR?" My answer to this is that the most important factor in the outcome of any operation is by far and away surgeon skill. The implant used is maybe the next most important factor.

Three surgeons have published excellent long-term results with the BHR. Derek McMinn is retired, Ronan Treacy is still going strong in Birmingham, England, and Peter Brooks is semi-retired at the Cleveland Clinic in Florida. You can’t go wrong with either of these fine surgeons. No other surgeon in the US has published long-term outcomes using the BHR. So, you can take a leap of faith and choose someone who has done a lot of BHRs but has published no data. All other published long-term outcomes (10-15 years) in the world are inferior.

But doing a BHR vs. doing a Recap/Magnum is not much different for a surgeon skilled in this operation. The only real difference is cementing vs. press-fitting the femoral component. I have cemented the first 1000 hip resurfacings that I performed prior to switching to uncemented in 2007. I probably know how to cement a femoral component. In analyzing comparison data between cemented an uncemented femoral components it appears that the long-term failure rate is approximately 1% higher when cement is used. I now publish 98% 19-year implant survivorship with the Recap Magnum system; therefore, I estimate 97% 19-year survivorship if I use the hybrid BHR, perhaps better if I exclude high-risk cases with osteoporosis and osteonecrosis.

If you are a man: BHR with an increasing chance of a backup of UC dual mobility THR if you are shorter. Unlimited supply.

If you are a woman: Polymotion if you meet the study criteria above and are willing to commit to the required follow-up. Limited supply.

Patients with extensive bone loss due to wear or underlying deformity (severe dysplasia, Legg-Perthes), osteonecrosis, or osteoporosis can no longer be done. You will need to have a THR.

Predict your chance of being fit with a BHR implant

We have analyzed our database of over 7000 hip resurfacings and found that the factor that best predicts implant size is patient height. This is important for men who are contemplating a BHR implant. The shorter a man is the smaller his femoral head is. If the head is smaller than 48mm, no BHR implant is available that will fit. The table below lists the odds that you will be able to get a BHR: