Why does my knee hurt when I cycle uphill? Ask the GP DR MARTIN SCURR

Question: I used to cycle 100 miles a week, but last year I began to have a knee problem. I could ride all day, but the moment I raised myself up to cycle uphill my left knee gave way. 

I’ve given up cycling for running and easily do three 5k runs a week, but can’t walk up a flight of stairs. If my leg goes past a certain ‘degree’ of bend, it gives way. 

Stuart A, by email. 

Answer: Your letter reminds me of a patient whose knee stuck at specific times, much like yours. He could play squash, but found it would suddenly cause him to collapse in pain on court. He could climb a ladder, but his knee would lock when walking up the stairs. 

I sent him to an orthopaedic specialist who ordered an MRI scan, which revealed a loose fragment of cartilage that became jammed in the hinge of the knee joint. 

I wonder if you, too, might have some sort of loose fragments in your knee and suggest asking your GP for a referral for an MRI. Any such fragments may be removed via keyhole surgery. You should then be able to return to all the activities you enjoy.

Question: I have suffered from bloating, gut distension and chronic constipation for years. A recent lactulose breath test showed I had very low hydrogen levels but an elevated methane level. I have been sent to a dietitian. Is there anything I can do to tackle this level of methane in my gut? I’m 66 years old. 

Colin Miller, Chester 

Answer: Hydrogen and methane breath testing is a non-­invasive way to diagnose common gastrointestinal problems such as bacterial overgrowth or food intolerance. As you will know, the test involves fasting for 12 hours before swallowing lactulose, a type of sugar, and then studying the levels of two gases (hydrogen and methane) produced by gut microbes into the air you breathe out. 

Gases are produced by the microbes as they break down the food we eat. Elevated hydrogen levels usually indicate intolerance to some sugars, such as milk sugar (lactose) and fructose (fruit sugar). As a result, more of these remain in the large intestine for bacteria to work on. 

Raised hydrogen levels can also be a sign of small intestinal bacterial overgrowth (SIBO) – meaning there are more bacteria than there should be in your small intestine (they are largely found in the large intestine). 

The more of these bacteria, the more gas they produce. However, we can discount both of these causes in your case given your low hydrogen readings. 

But your excessive methane level is evidence of an increase in certain types of organisms in the large intestine (including methanobrevibactersmithii) that feed off ‘fermentable’ carbohydrates, such as lactose or fructose. It is these that are causing your bloating, pain and constipation. 

This – together with your other symptoms – suggests you have a variant of irritable bowel syndrome associated with constipation: research has confirmed a significant link between the severity of constipation and raised methane levels. (The opposite is true in patients with irritable bowel syndrome with diarrhoea.) 

The usual treatment is a combination of antibiotics; prebiotics (which nourish beneficial bacteria); and probiotics (to boost levels of good bacteria in your gut). However, antibiotic treatment is not the best approach as the methane-producing organisms are often resistant to most antibiotics. 

I have suffered from bloating, gut distension and chronic constipation for years (stock photo)

Although the antibiotic medications rifaximin and neomycin are prescribed for some patients, these may upset other valuable parts of the microbiome. Dietary changes are the best way to obtain prebiotics and probiotics – that means increasing consumption of vegetables and fruit – and this is why you’ve been referred to a dietitian, who will be best placed to offer advice. 

It is a treatment that can take months. But it should gradually improve your microbiome, resulting in a resolution of many of your symptoms, so do give it time.

Write to Dr Scurr at Good Health, Daily Mail, 9 Derry Street, London, W8 5HY or email: drmartin@dailymail.co.uk. Dr Scurr cannot enter into personal correspondence. Replies should be taken in a general context. Consult your own GP with any health worries.