Simple '10 step' test could detect knee osteoarthritis

Osteoarthritis affects 45% of over 65s and costs the UK economy approximately 1% of its annual gross national product. The disease is a growing problem due to obesity and an ageing population.

Dr Rajshree Mootanah is the lead author of a study that analysed the walking pattern, or gait, of 1,678 adults with an average of age of 61. The findings were due to be presented last week at the American Academy of Orthopaedic Surgeons (AAOS) annual meeting in Chicago.

The research has demonstrated for the first time that gait asymmetry may be an indicator of knee osteoarthritis in older adults who were otherwise healthy.

The asymmetry indices (ASI) for single support (the period of time when only one foot is in contact with the ground) and stance times (the time from heel strike to toe off) were highest for individuals with osteoarthritis in one knee, or unilateral knee osteoarthritis. The test also detected a trend for single support time in bilateral knee osteoarthritis (in both knees) patients, as it is unusual for it to be of the same severity on both sides.

Dr Mootanah, Director of the Medical Engineering Research Group at Anglia Ruskin University, believes that GPs should be trained to spot signs of osteoarthritis.

"Subjects with unilateral knee osteoarthritis are likely to compensate for the affected limb by reducing the corresponding single support and stance times, hence the greater gait asymmetry for these parameters. However, unlike hip osteoarthritis there were not significant differences in step length or pressure exerted.

"There is no cure for knee osteoarthritis, but if GPs were encouraged to look for early signs it could have a significant improvement on how patients are treated and their quality of life.

"Each knee operation costs the NHS approximately £7,000, plus aftercare, and knee replacements only last around 10 years, meaning that subsequent operations might be necessary if carried out at an early age. The important thing is for people to delay having the operation for as long as possible because you only want to have it once, as subsequent operations are more invasive, less successful and have a longer recovery time.

"We hope that further research could help in assisting GPs to detect asymmetry in walking patterns. For example, by routinely watching their older patients walk into the surgery - 10 steps could be sufficient - and spotting the tell-tale sign of one foot taking longer than the other to be placed on the ground, the patient could be referred to a gait analysis lab or for an x-ray.

"If knee osteoarthritis is detected at an early stage then devices such as a knee braces, foot orthotics such as insoles in shoes, or drugs may improve clinical outcomes and delay the need for knee replacement. Unfortunately, at present it is detected far too late."

 The research was funded by a US National Institute of Health grant to Principal Investigator David Felson, MD, MPH, from Boston University. This study was conducted by scientists from Anglia Ruskin University, the Hospital for Special Surgery in New York, the Massachusetts General Hospital Institute of Health Professions in Boston, the Boston University School of Medicine, the University of California San Francisco School of Medicine, the University of Alabama and the University of Iowa.

This research was presented at the Orthopaedic Research Society meeting in Texas earlier this year, where it obtained first prize in the knee poster category.


Image:  Dr Rajshree Mootanah and Dr Howard Hillstrom



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