New study may help to identify osteoarthritis patients who can benefit from insoles

The results of a new study may help identify patients with medial knee osteoarthritis (inside the knee joint) who could benefit from wearing lateral wedge insoles.

These insoles can help people with the condition by reducing what is known as the external knee adduction movement (EKAM). However, in some cases wearing the insoles can actually cause EKAM to increase.

An Arthritis Research UK-funded research team at the Universities of Manchester and Salford investigated  why some patients react differently to wearing the insoles.

A team led by Dr Richard Jones analysed the gait of 70 osteoarthritis patients while walking in a control shoe and a lateral wedge insole. They assessed whether dynamic ankle joint complex coronal plane biomechanical measures - effectively assessing the movement of the joint - could be used to identify those participants who saw EKAM increase or decrease when using the insole compared to the control shoe. Prior to this, research had mainly focused on the knee joint rather than the ankle.

A third (33 per cent) of the patients experienced a rise in their EKAM, while for 67 per cent it fell. The researchers found lateral wedge insoles shifted the centre of foot pressure laterally as well as increasing eversion of the ankle/subtalar joint complex (STJ) and the eversion moment compared to the control shoe.

By assessing ankle angle at peak EKAM and peak eversion ankle/STJ complex angle in the control shoe, the researchers were then able to predict if patients were more or less likely to decrease EKAM under lateral wedge conditions.

The team, whose findings have been published in the journal Osteoarthritis and Cartilage, concluded that assessing coronal plane ankle/STJ complex biomechanical measures can play a "key role" in identifying patients who would benefit from wearing lateral wedge insoles.

A spokeswoman for Arthritis Research UK commented: "This study is one of several related projects at the Universities of Manchester and Salford aiming to find out if knee osteoarthritis can be improved by  correcting gait and posture, and changing the ways people walk in order to reduce pain."

She added: "Because of the way we walk, we have constant loading on the inside of the knee, which is linked to the progression of osteoarthritis. If this could be altered, the progression of disease could be affected."