The Complete Handbook of Crutches

Chapter 1: Understanding Crutches

A crutch is a load-bearing frame that transfers weight from the upper body to the ground, bypassing a weakened or injured lower limb. That is the entire principle. But the simplicity of the principle hides a surprising amount of mechanical and physiological nuance. To use, fit, maintain, or resell crutches professionally, you need to understand what happens at every point where the device meets the body and the ground, and what happens inside the frame when it carries a load.

Consider the most common scenario: a person with a fractured tibia leaving an emergency department with a pair of axillary crutches. In the first week, that person will put the full weight of their body through the crutches dozens of times per day. Each step involves a swing phase where the entire body weight is supported on the two crutches and the healthy leg. The crutches are subjected to compressive loads, bending moments, and shear forces at the handgrips and the tips. If the crutch is too short, the user stoops and puts excessive stress on their wrists. If it is too tall, the axillary pad presses into the armpit, compressing the radial nerve and causing the classic "crutch palsy"—numbness and weakness in the forearm and hand. This is not an abstract risk; it is a frequent cause of re-injury and poor patient outcomes. The device is simple, but the interface with the human body is not.

Anatomy of a Crutch

Every crutch, regardless of type