Simultaneous knee, foot support may improve knee OA management

By Lauretta Ihonor, medwireNews Reporter

Researchers report that concurrent use of a custom-made knee brace and foot orthotic produces greater reductions in pathologic knee adduction in patients with knee osteoarthritis (OA) than knee- or foot-support alone.

"The largest change in the knee adduction moment [during walking] occurred at its first peak and represented a 12% reduction," say Trevor Birmingham (University of Western Ontario, London, Canada) and colleagues of the combined orthotics.

The finding illustrates that medial compartment load can be decreased by using a dual knee- and ankle-support management strategy.

However, the team adds that it is "presently unclear" if this 12% reduction in the knee adduction moment during walking makes a noticeable difference to daily patient functioning.

Birmingham and colleagues recruited 16 individuals with a mean age of 55 years, varus alignment, and knee OA (mainly involving the medial compartment of the knee joint).

All underwent gait testing under four conditions: no knee brace or foot orthotic (control), knee brace only, foot orthotic only, and knee brace plus foot orthotic.

The greatest (and only significant) reduction in knee adduction moment was observed when participants wore a knee brace plus ankle orthotic.

This scenario produced a mean reduction in first peak knee adduction moment of 0.36% (normalized to bodyweight and height) compared with control.

A mean decrease of 0.59 cm in the lever arm of the frontal plane ground reaction force was also observed with dual joint support versus control.

This, say Birmingham and co-investigators, suggests that "decreases in the knee adduction moment observed with both devices are brought about through decreases in the frontal plane lever arm."

As reported in the Archives of Physical Medicine and Rehabilitation, some patients reported that the devices were uncomfortable to wear.

Birmingham and team therefore hypothesize that this reported discomfort may limit uptake of concurrent knee brace and foot orthotic use in real-life situations.

The researchers conclude: "These results do lend support to future work investigating potential additive effects of combined interventions tailored to ensure patient comfort."

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