A crutch is a specialized medical device designed as a temporary or long-term mobility aid. Its primary purpose is to transfer a user’s body weight from the lower limbs to the upper body, mainly the arms and torso. This apparatus allows individuals recovering from injuries, surgery, or chronic conditions to maintain upright mobility while protecting the compromised limb from bearing full weight.
Categorizing Crutch Designs
Crutches are categorized by where they interface with the user’s upper body, leading to three main designs. Axillary crutches are the most common, featuring a padded support that rests beneath the armpit and a separate handgrip. These are often used for acute, short-term injuries and are the type most frequently provided by healthcare institutions for immediate use upon discharge.
Forearm crutches, also known as Lofstrand or Canadian crutches, utilize a rigid cuff near the elbow and a handgrip. This design offers greater control and is often preferred for long-term mobility needs or for individuals with conditions requiring greater stability. The cuff allows the user to release the handgrip momentarily without dropping the device, which is an advantage over the axillary type.
Platform crutches are less common, designed for individuals who cannot grip the handles due to conditions like severe arthritis or wrist injuries. These models feature a horizontal trough that supports the forearm, shifting the weight-bearing surface away from the hands and wrists. The design transfers weight mainly to the forearms, which is helpful when peripheral joint pain prevents hand use.
How Crutches Facilitate Movement
Crutch movement is rooted in principles of biomechanical stability and load reduction. Crutches mechanically widen the user’s base of support, transforming the usual narrow stance into a broad, stable triangle. This foundation is created by the placement of the two crutch tips and the unaffected foot, necessary when one lower limb cannot support the body’s center of gravity.
This widening allows the user to achieve either non-weight bearing (NWB) status, where the injured limb is kept off the floor, or partial weight bearing (PWB), where a limited amount of load is permitted. By offloading the necessary force, crutches minimize the mechanical strain on the injured joint or bone, allowing tissue repair to proceed unimpeded. The devices serve as temporary extensions of the upper body, bypassing the need for full lower limb support during locomotion.
Essential Steps for Safe Use
Safe crutch use begins with precise measurement and fitting to prevent injury and promote proper posture. For axillary crutches, the top pad should rest approximately two to three finger-widths (about five centimeters) below the armpit when the user is standing upright. The handgrip must be positioned so the elbow is flexed at a slight angle, typically between 15 and 30 degrees, allowing maximum pushing power through the hands.
The user must bear weight through the handgrips, not by pressing the axillary pads firmly into the armpits. Sustained pressure on the armpit can compress the radial nerve or the brachial plexus, potentially leading to nerve damage known as crutch palsy. The correct weight distribution engages the shoulders and upper back musculature, protecting the delicate nerves that run through the axilla.
Different walking patterns, called gaits, are employed depending on the weight-bearing prescription. For non-weight bearing injuries, the three-point gait is standard, requiring the user to advance both crutches and the injured leg simultaneously. Navigating stairs requires specific technique: the phrase “up with the good, down with the bad” serves as a helpful reminder. When ascending, the uninjured leg moves first, while descending requires the crutches and the injured leg to move down together before the good leg follows.