Ian McDermott presents at The 2019 London Knee OA Meeting: How and why to avoid (or at least delay) knee replacement surgery.

The following blog is a summary of Mr Ian McDermott’s presentation at The 2019 London Knee OA Meeting at London Bridge Hospital on 20th June 2019. This meeting was held in conjunction with London Sports Orthopaedics, Össur and Technique Physio, and a copy of the webinar of the full meeting is available (see link at end of article).

What is osteoarthritis?

‘Wear and tear’, ‘degeneration’ and ‘osteoarthritis’ all kind of mean the same thing. We tend to say ‘there’s a bit of wear and tear’ when the joint damage in only fairly minor; but if the damage is severe, if the cartilage has completely worn away and if there’s bare bone rubbing on bare bone; then that’s fully-blown arthritis.

If someone says to me “I’ve got some arthritis in my knee”, then I really don’t know what, exactly, they’ve actually got, and I’m a full-time knee surgeon who does nothing but knees, day in day out! Have they got just a bit of chondral thinning? Do they have a degenerate meniscal tear? Have they got a small focal patch of full-thickness chondral loss or do they have widespread bare bone exposed? Is their arthritis affecting the whole joint or is it only in 1 or maybe 2 compartments? Is their ACL intact? Is the knee stable? Is there any malalignment? Are there any loose bodies?

So, when, for example, published studies talk about the treatment of ‘arthritic knees’, this really just isn’t even nearly enough detail when it comes to the actual diagnosis, let alone deciding on potential treatment options. The Kellgren and Lawrence grading system is often used by many people, but this is just a very basic simplistic grading system based purely on X-rays alone, and again, it does not give a full picture.

So, when deciding on potential treatments for an individual patient, the only way to manage a patient properly is the good old-fashioned way, relying on proper face-to-face medicine, with:

  • a full and detailed history
  • a proper hands-on clinical examination
  • a review of whatever imaging might be required (and imaging is always required), and then
  • a proper face-to-face two-way discussion with the patient, to explain to them exactly what their knee problem is, what their potential treatment options might be, and the pros and cons of each of those options.

I then send my patients away, and the patient will then get a copy of their clinic letter. I also e-mail my patients website links, advice sheets and articles, and I encourage them to get back to me with whatever potential further questions they might have. If there are just a few questions, then my patients usually e-mail me. If they end up with a long list of questions, then I encourage them to come back to clinic for a further face-to-face discussion. Only once the patient is fully informed about their diagnosis and their options can we then move on planning any actual surgery, if needed.

Simple statements are for simple people; because life’s just not that simple. Broad sweeping statements like ‘you treat knee arthritis with a knee replacement’ may roughly fit with a range of individuals within the roughly normally distributed population; but this approach is just simply wrong when it comes to the individual – the person who’s sitting opposite you in clinic. Therefore, real medicine involves tailoring the options according to what’s best for the individual patient.

Primary osteoarthritis or secondary?

One useful way of categorising arthritic knees is to consider whether the patient’s arthritis might be ‘primary’ or ‘secondary’.

‘Primary arthritis’ has a significant genetic component, and it often manifests as generalised damage throughout an entire knee joint, associated with damage to other joints around the body, often with a family history.

‘Secondary arthritis’ however, is where the damage in a knee joint can be attributed to a specific cause, such as:

  • previous trauma, e.g. meniscal tears/loss, ACL rupture, impaction injuries
  • previous infection: septic arthritis leads to widespread articular cartilage damage in a joint
  • malalignment: a varus deformity overloads the medial compartment; a valgus deformity overloads the lateral compartment; lateral patellar maltracking overloads the lateral side of the patellofemoral compartment
  • morphological abnormalities, such as patellar dysplastic (an L-shaped or flat patella instead of the normal V-shape)
  • focal osteochondral pathologies, such as Osteochondritis Dissecans.

One of the reasons that it’s so important to understand the potential underlying causes of whatever knee pathology you’re looking at is that often, focal localised problems can be treated with focal solutions, whereas if the patient is simply on their way towards developing widespread joint damage from primary osteoarthritis, then focal treatments will be likely to fail, and a more ‘global’ approach (such as total knee arthroplasty) might be indicated.

Is knee arthritis common?

Yes! The radiographic evidence of knee OA is:

  • 5% > 25yrs
  • 15% > 45yrs
  • 40% > 60yrs

What issues does it cause?

  • Pain
  • Reduced function
  • Loss of earnings
  • Reduction in quality of life
  • Increased weight
  • Decreased life expectancy
  • Huge burden to the individual
  • Huge burden to society

So, surely just get on and do a knee replacement??…

The negatives of knee replacement surgery:

  • Big op
  • Painful op
  • Time off work
  • Prolonged difficult rehab
  • Risks (infection, neurovascular damage, blood clots: DVT/PE)
  • Satisfaction not guaranteed
  • Wear and failure and revision
  • Revision twice as difficult

What are the ‘success rates’ of knee replacement?

Well this depends very much on one’s definition of ‘success’….

In terms of prosthetic survivorship figures:

  • 95% of knee replacement prosthesis will still be in place after 10 years, with only 5% having needed revision
  • 80% of knee replacements will still be in place after 20 years, with only 20% having needed revision

So, this concept of ‘they only last 10 years’ is rubbish!

However… the survivorship figures do vary depending on the patient’s age, which is a significant issue.

If you do a knee replacement in someone who’s older, then they generally tend to be less active. If the patient is less active then they’ll use the new knee less, which means that the rate of wear and tear on the artificial joint will be less. This means that the new joint will probably last longer. Added to this: older patients don’t tend to live as long as younger patients. So –

  • If you do a knee replacement in someone in their 70’s, then there only a roughly 10% chance of it failing within the patient’s lifetime and needing a revision, and a 90% chance that the prosthesis will outlast them! 

Conversely, if you put a knee replacement into a patient who is younger, then the younger someone is, the more active they’re likely to be, and hence the faster the rate of wear and tear on the knee prosthesis, and hence the more likely it is to wear out somewhat sooner rather than later; combined with the fact that younger people tend to live longer, and hence the knee is in place for more years, so –

  • If you do a knee replacement in someone in their 50’s, then there a roughly 50% chance of the patient ending up needing a revision within their liftetime!

Revision (re-do) knee replacement surgery is twice as big and technically complex and primary (first time) knee replacement, with double the potential complication rates, with slower and more difficult recovery / rehab, with poorer outcomes (in terms of patient outcomes), and with higher potential failure rates. Therefore, if a revision can be avoided, then it should – and one of the best ways to reduce the probability of future revision surgery is to avoid, if possible, putting knee replacements into younger, more active patients.

So, when is the right time to go ahead with knee replacement surgery?

Simple – read this link! …


So, what else can we do to delay total knee replacement surgery?

There’s a lot that can be done before we potentially end up having to resort to total knee replacement surgery:

And finally, if you do end up having to have a total knee replacement, then my personal advice is to go for the best! – and the best prosthesis out there currently is the custom-made knee from Conformis:

However… if you’ve got a varus or valgus deformity in your knee, and if you’re still active and if you want to try and delay joint replacement surgery… then you should at least try an offloading knee brace:

  • a medial offloading knee brace for patients with a varus knee (bow-legged), or
  • a lateral offloading knee brace for patients with a valgus knee (knock-kneed),

and the brace that I recommend for my patients is the Unloader One brace from Össur or the Össur Rebound Cartilage brace –

This is a picture of a medial offloader brace: as the brace mechanism is tightened, a progressive valgus force is applied to the joint, which offloads the medial compartment.

To hear the full presentations about the role of braces in the treatment of knee OA, click on this link, which is a recording of the webinar from The 2019 London Knee OA Meeting at London Bridge Hospital on 20thJune 2019:



Ian McDermott




Mr Ian McDermott


18 July 2019


Ian McDermott