What Are the Differences between a Waddling Gait and a Trendelenburg Gait?

A Trendelenburg gait occurs when the hip abductor muscles are weak on one side. These muscles normally keep the pelvis level while walking. When the affected leg bears weight, the opposite side of the pelvis drops—a sign known as a positive Trendelenburg sign. Since only one hip muscle group is affected, the person often leans toward the weak side to maintain balance. A waddling gait, by contrast, results from weakness in both hip muscles. This bilateral weakness makes the pelvis unstable, causing the person to sway side to side—or "waddle"—while walking. This swaying motion helps compensate for the weakened muscles during each step. The main distinction between these gaits is that a Trendelenburg gait involves one-sided weakness with dropping of the opposite pelvis, while a waddling gait stems from weakness in both hips.