A pin suspension system used to keep an artificial lower-leg in place can disrupt circulation within the remaining limb, leading to skin sores, investigators report. They suggest prostheses that use suction attachment are a better choice.

Both pin and suction suspension prostheses are commonly used by people who’ve had a below-the-knee amputation, Dr. Glenn M. Street and Tracey L. Beil from the Human Performance Laboratory at St. Cloud State University in Minnesota explain.

“Pin suspension has raised concerns among a number of prosthetists who regularly observe daily swelling and dark red discoloration of the (far) end of the residual limb,” they point out in the Journal of Rehabilitation Research & Development.

To investigate, the two researchers measured pressures between the artificial leg and the amputated limb during standing and walking with pin and suction suspension systems. A total of eight amputees participated in comparing the two types of device.

There were no pressure differences between the two modes of suspension while standing.

However, during the swing phase of walking, the pin system significantly compressed the upper residual limb while creating large negative pressure at the lower end. “This pressure combination is likely the cause of the daily and chronic skin changes observed in pin liner users,” Street and Beil conclude.

They point out that 50 to 70 percent of people who have a lower-leg amputation are suffering from diabetes, and for them “complications imposed by pin suspension can be debilitating.”

Suction suspension does not create these adverse pressure distributions and might be a better option, the team says, especially for amputees with very active lifestyles.

SOURCE: Journal of Rehabilitation Research & Development, November/December.