For several years, Nick London has been a vocal advocate of the Persona Partial Knee, the surgical implant he helped develop with Zimmer Biomet. So why has he made the decision to exclusively use the Enovis Physica ZUK in all his partial knee replacements? In this article, he explains his reasoning.

One of the most important aspects of your partial knee replacement (aka partial knee resurfacing) procedure is the implant your knee surgeon uses. For several years now, I’ve used two. For replacement of the lateral (outer) compartment of the knee I’ve used the Physica ZUK, an implant manufactured by Lima Corporate, although recently they have been acquired by US organisation Enovis.

For replacements of the medial (inner) compartment of the knee, and since its launch some six years ago, I’ve favoured the Persona Partial Knee (PPK), an implant I helped to develop with manufacturer Zimmer Biomet.

Exceptional implants

Both implants, I believe, remain the two best performing partial knee replacements in the world. That’s borne out by their National Joint Registry data and ODEP ratings. ODEP is the rating panel that provides an objective view of the strength of evidence supporting an implant.

Two variants of the Physica ZUK have 10A* and 13A* ratings. The PPK’s rating is 5A* (you can find more on ODEP ratings here). These ratings are as good as it gets, with the only difference (obviously) being the number at the start, which represents the number of years for which evidence has been available. Inevitably, it’s impossible to show ten or thirteen years of evidence when your implant hasn’t existed for that long.

You might reasonably ask whether an implant that has so many years of evidence behind it (and which has actually been on the market for 20 years) can possibly be as modern and innovative as a newer model, but the Physica ZUK has never stood still, with instrumentation, patient selection and education refined and developed over the years. It’s still very much an up-to-date implant with class-leading instrumentation and class-leading worldwide joint registry results.

Compare the two implants side by side using five year results (the only results against which it’s possible to evaluate the PPK at present) and they are virtually identical.

So why am I switching to only using the Physica ZUK, when I spent years working with Zimmer Biomet to develop the PPK?

The answer, in a single word, is this: education.

Why education matters

Education is the primary reason for my shift. Since purchasing the ZUK (confusingly, Lima bought it from Zimmer – I shan’t bore you with the details) Lima Corporate has been consistent in its provision of surgeon education. Since its acquisition, Enovis has also remained strongly committed to surgeon education.

This, I believe, is vitally important. The evidence shows partial knee replacements are suitable for as many as 50% or more of knee replacement patients. Compared with total replacements, partials lower surgical risk. Outcomes are better. Patients recover faster. With partial knee surgery, considerably more bone is preserved (hence – they should be termed partial knee resurfacing rather than ‘replacement’).

Crucially, they offer more reassurance if surgery is necessary at a younger age, because a partial knee replacement can be followed by a total replacement if the partial eventually loosens or wears out. A total knee replacement, however, can only be followed by a ‘revision knee replacement’ – an operation with higher risks, poorer outcomes and the need to remove substantially more bone. In our experience, the chances of a partial knee failing and requiring further surgery is not significantly greater than the chances of a total knee replacement failing.

Yet only 10%-15% of patients globally receive partial knee replacements and the main reason for that is the lack of surgeon training and, therefore, experience.

A tale of two ideologies

Enovis is now building on Lima’s track record in education with a very strong, bold plan for delivering surgeon education in the UK and Europe and further afield over the coming years.

Contrast that with the position at Zimmer Biomet. I’ve spent the last four to five years through Covid and beyond trying to encourage Zimmer Biomet to provide more surgeon education specifically for fixed-bearing partial knee implants. Unfortunately, I (and others) have been largely unsuccessful. Zimmer Biomet is an excellent company with a long history of providing education to surgeons in addition to outstanding implants. Sadly, their focus in recent years has been on developing and promoting robotic-assisted surgery and supporting a mobile-bearing partial knee implant despite inferior registry results.

Frustratingly, then, I’m of the view that the company’s commitment is more to fighting ‘robot-wars’ and less to surgeon education. And as we’ve covered on these pages previously, the YKC view is that robots currently offer increased costs and potentially increased risks without any significant advantages particularly with partial knee surgery.

Of course, Enovis is also exploring technological solutions and assistive technology, but the focus is clearly different. Their commitment to fixed-bearing partial knee resurfacing (the gold standard in my opinion) is unparalleled.

A note for patients

I really should stress that for patients, I’m choosing one exceptional implant over another exceptional implant. If you’ve already had a partial knee replacement using a PPK, you can feel extremely confident in the implant you’ve received.

But in making this change, I’m hoping that many more patients will be able to benefit from such exceptional implants.

To explore options for your partial knee replacement, please contact us or phone us on 03453 052 579.

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