As the UK swelters under a heatwave that may surpass the record summer of 1976, a leading surgeon has warned about an often overlooked danger: the impact of dehydration on joints. Professor Paul Lee, a joint preservation specialist, says cartilage is approximately 70 to 80% water and that failing to drink enough could leave it starved of nutrients.
“Most people think about dehydration in terms of feeling thirsty, tired or dizzy,” said Professor Lee. “What they often don’t realise is that cartilage relies on hydration and movement to maintain joint health.” Unlike many tissues, cartilage has no direct blood supply; it receives nutrients through fluid movement within the joint. When dehydration occurs, that process becomes less efficient – “like a sponge”, he explained.
“Surgeon warns dehydration during heatwave can damage joints, as cartilage is 70-80% water.”
To help people stay properly hydrated, Professor Lee recommends what he calls the “rule of six”: no more than six hours without drinking water during the day, no more than six hours without passing urine while awake, and urine no darker than pale straw. He also advises avoiding excessive alcohol and seeking medical advice if dizziness or confusion sets in.
The advice comes as temperatures edge towards the 1976 record of 35.9C in Cheltenham – a summer remembered for its severity but also for a Britain that was far less equipped to cope. In London, outdoor swimming pools were seen as the preserve of eccentrics, bottled water was not yet a thing, and men would never wear shorts anywhere but the beach. Pubs closed in the afternoons and at 11pm on weeknights, while the city itself was still scarred by bomb damage and bad Sixties planning.
“I often tell patients to protect their cartilage with the 6x6 rule,” said Professor Lee. “Stay hydrated enough to pass pale urine at least every six hours. It’s a simple way to monitor whether your body is getting enough fluid.” The warning is particularly important for older adults, people with arthritis, and anyone spending long periods outdoors. “We often focus on exercise, treatments and medications, but basic hydration is one of the foundations of healthy joints,” he added.