Canes, crutches and walkers are safe and effective but generally underutilized therapeutic tools. These aids are most helpful to patients who have an unstable gait, whose muscles are weak or who require a reduction in the load on weight-bearing structures. An understanding of the biomechanics of ambulation aids provides insights into how and when these devices should be prescribed. The patient must have sufficient strength, balance and coordination to master the aid and should be trained to use it correctly.