Doctors in Singapore have not seen any instances of people having blood supply to their legs reduced because of super-tight "skinny" jeans.

A 35-year-old woman in Australia who squatted in skinny jeans ended up with legs so swollen her jeans had to be cut off. Her case - reported in British specialist publication Journal Of Neurology, Neurosurgery And Psychiatry two weeks ago - raised concerns about the health risks posed by wearing such jeans.

The woman may have developed compartment syndrome, in which pressure within muscles increases to an extent that it reduces blood flow and oxygen to them, said Dr Roger Tian, medical director of the Singapore Sports Medicine Centre.

The term "compartment" refers to an area of the body - usually the arms and legs - which is surrounded by thick, unyielding layers of tissue called fascia, which does not allow its contents to expand much, said Dr Tan Chyn Hong, an orthopaedic surgeon at Mount Elizabeth Novena Specialist Centre.

But compartment syndrome is so rare that Dr Tian and Dr Tan see fewer than 10 cases each a year.

There are two types of the syndrome - acute and chronic. An acute case occurs when there is injury to a limb, such as fractures. Up to 9 per cent of leg fractures lead to compartment syndrome, according to an overseas study.

Dr Tan said bleeding and swelling from a fracture, dislocation or muscle injury causes pressure in the limb to rise. Muscles and nerves will start to die unless the pressure is released by slicing open the tightened fascia within six hours. If not treated early enough, the dead tissues would release toxins into the bloodstream, and amputation may be required, Dr Tan said.

Running is the most common cause of chronic compartment syndrome. Dr Tan said: "Exercise increases the amount of blood flow in the legs to meet their increased metabolic demands. However, the tight compartment doesn't allow much expansion and pressure starts to rise." The good news is, chronic compartment syndrome is usually not dangerous, said Dr Tan.