Can Cycling Lower Your Risk Of Knee Arthritis?

Picture by Dennis Thong

I have written previously on what causes osteoarthritis (OA). Definitely not because of overuse nor a mechanical wear and tear process. Especially for those without any previous history of knee truma/ injury, there is very good evidence that OA is actually due to metabolic factors. Well, now a new study (Lo et al, 2024) suggests that cyclists are less likely to develop OA in their knees.

Lo et al (2024) studied 2600 older adults with and without knee OA using knee X-rays, subjective knee pain, and a questionnaire regarding their lifetime history of various physical activities during 4 periods of their lifes: 12 to 18 years old, 19 to 34, 35 to 49 and over 50. 

The study used 3 different outcomes. Persistent knee pain, OA based on X-rays (radiographic OA) and symptomatic OA (having both knee pain and radiographic OA. Note that what is seen on X-ray (OA knees) does not always correspond to pain. This means that some subjects had knee radiographic OA but NO pain.

Almost half the subjects reported some history of cycling and these subjects were less likely to have OA in their knees. How much less? Those with any history of cycling were 17 percent less likely to have knee pain, 9 percent less likely to have radiographic OA and 21 percent less likely to have both. 

Half of those who cycled reported only cycling regularly during one of the 4 age periods, usually the youngest age period from 12 to 18 years old.

Those who cycled during 1,2,3 or 4 of the periods studied reduced their risk of symptomatic OA (i.e. painful knees) by 17, 19, 28 and 43 percent. Meaning lifelong cyclists reduced their risk of symptomatic OA by nearly 50 percent.

The researchers also found that subjects with a history of swimming, strength training and running had lower rates of OA. This is consistent with previous evidence that running DOES NOT ruin your knees despite what every non runner and ex runner you know will insist running does.

You may love watching the beautiful game, but a history of playing the beautiful game (football) even just as a teenager bumped up knee OA risk by a factor of 2. This elevated risk remained even after adjusting for BMI, suggesting that the problem is likely related to acute knee injuries suffered while playing football. 

Picture by Dennis Thong

The researchers concluded that more cycling is associated with less knee pain and favorable to knee health and should be encouraged. 

If you have never cycled previously and would like to start, do note that almost half or the current or former cyclists in the study had radiographic evidence of OA. A quarter of them had symptomatic OA (painful knees). Is cycling better for OA once you do develop OA compared to say running? Is cycling capable of slowing its progression? Currently, we still do not know.

Those of you who have been always been cycling, you definitely have another reason to do so. 

Reference

Lo GH, Richard MJ, Kriska AM et al (2024). Bicyling Over A Lifetime Is Associated With Less Symptomatic Knee Osteoarthritis : Data From The Osteoarthritis Initiative. Med Sci Sp Ex. DOI: 10.1249/ MSS 0.0000000000003449

All pictures by Dennis Thong. Many thanks to Dennis and Eugene Phua for the pictures.

Steroid Injections Accelerate Damage To Joint Surfaces

Picture from Ortho Arizona

Many patients with knee osteoarthritis (OA) who come to see us in our clinics often tell us that they were given intra articular (inside the joint) corticosteroid injections (IACS). ICAS is a common treatment choice that is considered minimally invasive to delay knee replacements for patients with severe OA. 

Other than providing brief pain relief, the pain often comes back. I wrote earlier this year that steroid/ cortisone injections significantly increases the risk of tendon tears.

Perhaps it's time to think more than twice before you allow anyone to inject into you knee joint. Make it any other joint for that matter as latest published research shows that individuals who got IACS were twice as likely to have harmful effects on knee articular cartilage structure than those who received no or placebo treatment.

Different stages of articular cartilage damage

A group of researchers investigated the effect of IACS on articular cartilage structure in patients with knee OA using joint space width on x-ray and articular cartilage thickness with MRI.

They found 6 studies consisting of a total pf 1437 participants. The estimated effect of IACS on articular cartilage structure showed significant odds of it worsening as measured by joint space narrowing and articular cartilage thickness. The authors concluded that their meta- analysis showed that IACS increases the likelihood of knee joint deterioration.

Other than increasing the risk of tendon tears, steroid/ cortisone  injections into knee joints may be doing more harm than good by accelerating joint surfaces degeneration. The short lasting pain relief is definitely not worth the long term consequences of your articular cartilage degenerating. 

Reference

Ibad HA, Kasaeian A, Ghotbi G et al (2023). Longitudinal MRI-defined Cartilage Loss And Radiographic Joint Space Narrowing Following Intra-articular Corticosteroid Injection For Knee Osteoarthritis: A Systematic Review And Meta-analysis. Osteo Imaging. DOI: 10.1016/j.ostima.2023.100157

Does Your Kneecap Position Matter?

Recently we saw quite a few patients after they had knee replacement surgery in our clinics. Having treated many patients' knees over the years, I have seen lots of variations of how the kneecap (or patella) is positioned.  Some patients have kneecaps that are 'aligned' nicely, yet they regularly complain of knee pain. Others have kneecaps that seem to sit terribly yet they have no knee pain nor need a knee replacement. 

There is definitely still a lack of knowledge regarding the variability of patellofemoral (kneecap) alignment in both healthy and osteoarthritic knees. Yet, while training to be physiotherapists, we were taught about the importance of kneecap alignment. They said it should sit nicely in the middle of the knee, and the sulcus and patella tilt should be a certain "normal" angle.

When patients come into our clinics complaining of knee cap (patella) pain, it is not always due to knee cap alignment. Hochreiter and colleagues (2020, 2021) published 2 systematic reviews demonstrating that both healthy and osteoarthritic knees have highly variable patellofemoral (knee cap) alignment.

15 studies met the inclusion criteria for healthy knees while 8 studies were used for osteoarthritic knees.

The authors concluded that both healthy and osteoarthritic knees have extremely variable patellofemoral alignment. This may be due to variables when doing x-rays/ MRI scans, measuring techniques and the people studied. 

R Kneecap position

In order to treat patients with healthy knees with knee pain, a more precise knowledge of the complex relationship between the trochlea and patella (pictured above) is needed since the exact role of knee joint alignment in development of knee pain/ symptoms remains unclear. I have written previously that the hip, especially in females, and not so much knee alignment causes knee pain.

The authors also suggest that surgeons operating on osteoarthritic knees need to consider individual pre-operative patellofemoral alignment if they want to reduce anterior knee pain for patients after total knee replacement surgery. Note that running will not wear out your knees (or your joints). So what does? There is now evidence that osteoarthritis is not due to a mechanical aging process. Even if you already have osteoarthritis, exercise will not wear out your joints quicker.

So healthcare professionals should not be telling patients that their knee joint alignment is abnormal, especially since we do not even know what normal alignment is.

References

Hochreiter B, Hess S, Moser LB et al (2020). Healthy Knees Have A Highly Variable Patellofemoral Alignment: A Systematic Review. Knee Surg Sports Trau Arthrro. 28: 398-406. DOI: 10.1007/s00167-019-05587-z.

Hochreiter B, Moser LB, Hess S et al (2021). Osteoarthritic Knees Have A Highly Variable Patellofemoral Alignment: A Systematic Review. Knee Surg Sports Trau Arthrro. 29: 483-490. DOI: 10.1007/s00167-020-05928-3.

Viscosupplementation (Gel Shots) For Your Knees?

Picture from whichmedicaldevice.com

Many of our patients have been asked to do a hyaluronic acid injection when told that their knees were "worn out" due to osteoarthritis.

Hyaluronic acid injections (also commonly known as gel shots) are thought to help with restoring the joint fluid (synovial fluid) composition to help with lubricating and providing shock absorption to the joint. They are often suggested for patients with mild to moderate osteoarthritis to alleviate pain, reduce friction and hopefully delay surgery (total knee replacement).

The following paper is a *systematic review and meta-analysis of the largest collection of randomised trials of whether hyaluronic injections are helpful for knee osteoarthritis.

169 trials involving 21,163 patients were first identified through searches from Medline, Embase and Cochrane Register of Controlled trials. Only randomised trials with more than 100 participants per group comparing viscosupplementation with placebo or no intervention were accepted. Patients were usually given a single course of 2 to 6 injections.

Of these, 24 large, placebo controlled trials (8997 randomised patients) were included in the main analysis found that viscosupplementation (or using hyaluronic acid injections) offered a small but strong conclusive reduction in pain intensity compared with a placebo injection. 

This translated to a margin of 5 mm on a 100 mm visual analogue pain scale (or half a point on a scale of 0-10). That's a really tiny pain reduction in my opinion.

However, based on 15 large, placebo controlled trials (6463 patients), viscosupplementation was associated with a statistically significant higher risk of serious adverse events compared to a placebo.

Serious adverse events were defined as resulting in hospital admission, prolonged hospital stay, persistent or major disability, congenital abnormality of offspring, life threatening events or death.

Hence, the authors of this systematic review concluded that the findings do not support the use of viscosupplementation for the treatment of knee osteoarthritis.

Still keen on getting a hyaluronic acid injection? Mark Philippoussis (nicknamed "The Scud" after the scud missile), was a former professional tennis player known for his awesome serve. He famously used hyaluronic acid injections every 6 months for his knees to enable him to keep playing after 3 knee operations. 

But he was a former professional who was a finalist in the 1998 US Tennis Open and 2003 Wimbledon Tennis tournament.

Reference

Pereira TV, Juni P, Saadat P et al (2022). Viscusupplementation For Knee osteoarthritis: Systematic Review And Meta-analysis. BMJ. 378: e069722. DOI: 10.1136/bmj-2022-06972

*A systematic review meta analysis is a search aided by computer looking for all randomized and clinically controlled studies while a meta-analysis means using statistics to combine the data derived from a systematic review. 

What Really Wears Out Your Joints

Picture by Dr Howard Luks

I remember treating many cases of older patients who had total hip or knee replacements due to osteoarthritis (OA) when I was a much younger physiotherapist. 

Upon asking these patients, they always wondered why they had worn out their joints despite not exercising. Some were very sedentary, while others had no time to exercise since they were more concerned with making enough to feed their families.

I've written previously that running will not wear out your knees (or your joints). So what does? There is now evidence that OA is not due to a mechanical wear and tear process. Even if you already have OA, exercise will not wear out your joints quicker. 

Of course there are mechanical causes of OA. People who are severely bow legged or have severely knocked knees can be more prone to developing OA since one side of the knee joint is over loaded. Certain fractures near a joint can lead to post traumatic OA (due to mal- alignment). 

Patients whose meniscus is torn and subsequently removed have an increased risk of developing OA. Which is why surgeons now rarely remove the whole meniscus, just the torn bit.

So, what causes arthritis in our joints? For those without any previous injuries to the joint, we have hundreds of proteins, cytokines, chemicals and other compounds that forms the articular cartilage, which lines our joints. When the joints are in good health, these chemicals support articular cartilage health and nutrition.

We do not know exactly why, whether it is due to injury, our diet, metabolism or weight that, OA develops. It may be all of the above when a 'switch' flips. Changes in the joint(s) similar to changes associated with other chronic diseases happens. That switch causes an increase the production of chemicals that harms our articular cartilage (Wang et al, 2015).

Over time, these chemicals cause injury to the articular cartilage cells. This weakens the articular cartilage and its ability to withstand load and stress.

The articular cartilage can become thinner when not functioning well. This can lead to inflammation, swelling, warmth and pain. This chronic low grade inflammation is what appears to cause OA. This is the same chronic inflammation thought to cause other chronic diseases like heart disease, fatty liver and Type II diabetes.

Researchers are still trying to understand how all these proteins and substances affect articular cartilage health and the incidences of OA. 

Exercise has actually been proven to decrease the concentration of these proteins and substances that harm our articular cartilage.

Helmark et al (2010) showed that IL-10, a chemical that protects articular cartilage in the knee was produced in response to exercise. Similarly, COMP (a protein that is a marker of cartilage degeneration) was decreased in the knee with exercise.

Another research paper by Hyldahl et al (2016) demonstrated that running was associated with a decrease in cytokines (chemicals) in the knee related to articular cartilage wear and tear. 

Studies are suggesting that metabolic health definitely plays a bigger role in causing OA. Yes, other than Type II diabetes, dementia, high blood pressure and heart disease, metabolic issues are also thought to be involved in the development of OA. All tissues in our body, including our articular cartilage are sensitive to our dietary intake. The earlier we realize this, the better off we will be.

Too many health care professionals ask their patients to stop running (or exercise) to 'save' their joints. In actual fact, running and other knee exercises have been shown to relieve mild knee arthritis and does not harm articular cartilage.

Exercise has been unequivocally proven to be the most effective treatment for early and moderate OA in our joints. You do not have to stop exercising. 

Let your symptoms be your guide. If there is no swelling and no pain, you can still run or exercise. Be careful with the distance, intensity and frequency of exercise. You may also want to cycle or swim occasionally. Or try a different shoe, or different running surface and/ or include a weight training session to get yourself stronger. 

References

Helmark IC, Mikkelsen UR, Borglum J et al (2010). Exercise Increases Interleukin-10 Levels Both Intraarticularly And Peri-synovially In patients With Knee Osteoarthritis: A Randomized Controlled Trial. Arthritis Res Ther. 12, R126. DOI: 10.1186/ar3064

Hyldahl RD, Evans A, Kwon S et al (2016). Running Decreases Knee Intra-articular Cytokine And Cartilage Oligomeric Matrix Concentrations: A Pilot Study. Eur J Appl Physiol. 116 2305-2314. DOI: 10.1007/s00421-016-3474-z

Wang X, Hunter J and Xu CD (2015). Metabolic Triggered Inflammation In Osteoarthritis. OA and Cartilage. 23(1): 22-30. DOI: 10.1016/j.joca.2014.10.002