By: 9 November 2015
Going weak in the knees – Simon Moyes

Going weak in the knees

Consultant orthopaedic surgeon Simon Moyes looks at the risks involved when treating knee damage and the possibilities for treatment

The knee is the largest joint in the body, and the most easily injured. Knee damage is common, but the prevalence of cartilage damage, and degeneration especially, is on the rise. The rubbery meniscus cartilage can get injured by twisting, pivoting or through direct contact. The hard articular cartilage can also get injured, either by trauma, general wear and tear or by poor blood supply to the joint.

Simon Moyes, a London-based consultant orthopaedic surgeon specialising in arthroscopic surgery for knee, shoulder, foot and ankle problems, sees many patients with damaged knee cartilage. He talks more about the risks involved and the possibilities for treatment.

Q: Why has there been an increase in patients with knee problems?

Simon: This is for a number of reasons. One problem is that we are all living longer. As the life expectancy continues to rise, the result is an ageing but active population and because of this we will be seeing more cartilage degeneration.

The obesity crisis also plays a big part. Extra weight doesn’t just have resulting consequences on an increased risk of heart disease and diabetes – it also leads to increased incidences of knee damage and replacement.

Being overweight puts an enormous strain on the knee – biomechanically nine times your body weight goes through the knee when you are just walking around doing general day-to-day activities. If you are five stone overweight then you are essentially carrying an extra 45 stone – which is being forced through your knee. The rates of obesity are rising and with it the rates of associated degenerative change in the knee with the need for further physiotherapy, arthroscopic surgery, intra-articular injections and joint replacement surgery also increases.

Another factor is exercise – while more people are exercising to keep fit, it is not as regular or consistent as it could be. Exercise without guidance or preparation can also lead to meniscus cartilage damage, so direction and support from professionals is a necessity.

Q: What types of cartilage are there?

Simon: There are two types of cartilage in the knee: hyaline cartilage and the meniscus, which acts as a shock absorber. If this becomes torn, it can be extremely debilitating and painful. The issue is that most meniscus tear surgery will remove the damaged cartilage rather than repair it.

Q: How should we try to improve this?

Simon: We should be doing far more in the way of restorative surgery. The problem with resections is that they can increase chances of arthritis down the line. The latest restorative technology is becoming more accessible, and patients should know that it exists – whether this be in the public or private sector.

Q: What treatments are available?

Simon: Repairs to torn menisci can be carried out with a combination of stitching and the use of stem cell technology. Damage to hyaline cartilage can be repaired with a technique called microfracture surgery – these use tiny drill holes to expose bone marrow stem cells, which, in turn, generate neo-cartilage to cover the bone.

Surgeons can also use a range of cell treatments or cartilage grafting. A small amount of cartilage stem cells are taken from the knee, multiplied in a laboratory and turned into a sheet of new cartilage, which, six weeks later, can be re-implanted into the knee. Healthy knee cartilage is taken from where it isn’t needed and moved to an area where it is needed.

Transplanted cartilage from a donor can also be effective. Viscosupplementation can reduce pain for people with arthritic knees, improve function and help cartilage heal.

Q: How can stem cells be used in the treatment for cartilage damage and repair?-

Simon: Stem cell technology is moving at a fast and exciting pace. There will shortly be a system where stem cells can be taken from your own fat and injected into your knee. We know that this can produce an 80 per cent reduction in arthritic symptoms in 80 per cent of patients.

Restorative techniques are more involved than routine keyhole surgery, and the patient is out of action for longer. However, ultimately, these techniques are more beneficial to the patient in the long term as the damaged joint surfaces are restored and reconstructed rather than being simply removed. To improve patient care and long-term outcomes, it’s important that more is done in this way of restorative orthopedics.


Simon Moyes consults out of The Wellington Hospital in St John’s Wood and 31 Old Broad Street in London. He does six private clinics a week and two full operating lists per week. Moyes’s main orthopaedic interests are arthroscopic and minimally invasive treatment of problems of the knee, shoulder, foot and ankle. Research interests currently are development of minimally invasive and arthroscopic techniques for the knee, shoulder, foot and ankle.