March 2017

Out on a limb: In search of symmetry

By Jordana Bieze Foster, Editor

Researchers and clinicians who work with unilateral lower limb amputees are increasingly exploring the effects of prosthetic devices on gait asymmetries and joint loading. What’s less well known is that prostheses designed for use above the waist can also have positive effects on gait.

As LER senior editor Emily Delzell details in this issue’s cover story (see “Knee OA in amputees: Biomechanical and technological considerations,” page 18), gait asymmetries related to unilateral lower limb amputation can increase the risk of knee osteoarthritis in the intact limb, but improving prosthetic fit and function can help reduce that risk by making gait more symmetrical.

Losing an arm or a breast doesn’t have the same direct effect on lower extremity function, but it makes sense that the asymmetries associated with those procedures could adversely affect balance and gait, and a handful of studies in the literature seem to support this.

In a 1996 study, German researchers reported that upper extremity amputees compensated by shifting the trunk toward the affected side and increasing gluteus medius activity on the affected side, potentially increasing stress on the hip. In 2012, another German group found similar compensations during gait in patients who had undergone shoulder disarticulation—but also found that wearing an arm prosthesis with a mobile shoulder joint helped to improve posture and reduce knee loading in the affected limb during gait.

Most recently, in a study epublished in early March by Breast Cancer Research and Treatment, Polish investigators found that static weightbearing differed significantly between limbs in women who had undergone unilateral mastectomy without reconstruction five to six years previously. They also found that foot shape differed significantly between limbs, which the authors suggested could represent the cumulative effect of the weightbearing imbalance over time.

In that study, about half of the 128 women said they used an external breast prosthesis during the daytime; another 37.5% said they used one only occasionally. However, the study did not analyze the extent to which the weightbearing and foot-shape asymmetries they found in the group overall might have been related to external prosthesis use.

Like lower extremity prosthetic devices, those designed for use above the waist can also have positive effects on gait symmetry.

The authors also did not specify whether the prostheses used were weighted silicone devices, designed to approximate breast tissue, or the soft, lightweight forms that are typically used immediately after surgery but sometimes are used in the longer term, especially while exercising or in hot weather. These different types of prostheses presumably would have different effects on biomechanical symmetry, despite having similar cosmetic effects when worn under clothing.

This month’s cover story points out that gait-related challenges in amputees—including knee pain and degeneration—often take a back seat to issues related to residual limb pain, phantom pain, and skin breakdown.

I suspect that in patients who have experienced breast or upper limb losses, gait asymmetries tend to be even less of a priority than in lower limb amputees. But, with patients living much longer after such procedures and rates of lower limb joint degeneration on the rise, I also suspect those priorities will need to change.

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