The typical orthopedic walking boot, such as a controlled ankle motion (CAM) walker, is designed with a thick sole and often a rocker bottom. This design protects the injured limb and facilitates a natural roll-through during walking. This necessary design creates a significant height difference between the booted foot and the regular shoe worn on the opposite, uninjured foot. This resulting temporary leg length discrepancy (LLD) disrupts the body’s natural alignment and gait cycle. A shoe lift or leveler worn on the non-booted side is a common, recommended solution to restore symmetry and mitigate the physical strain caused by this imbalance.
The Biomechanical Necessity of Compensation
The difference in limb length caused by the walking boot forces the body to adopt an altered walking pattern. This imbalance introduces measurable changes in joint mechanics. Specifically, the boot affects the sagittal and frontal plane hip mechanics, as well as the transverse plane knee mechanics, leading to a less symmetrical stride.
Without compensation, the LLD causes the pelvis to tilt, which leads to a lateral lean of the trunk as the body attempts to maintain balance. This unnatural posture places increased and uneven stress on the musculoskeletal system. The strain is often concentrated in the lower back, hips, and the knee of the uninjured leg, potentially leading to secondary pain or injury. Research indicates that using a corrective lift can improve step symmetry and reduce the degree of pelvic tilt and trunk lean. While a lift may not restore all aspects of normal walking mechanics, it helps to level the hips and reduce overall body strain.
Types of Shoe Lift Compensators
Purpose-built shoe levelers are available to address the height difference created by walking boots. These commercial products typically strap onto the shoe of the uninjured foot. One common type is the multi-layered, adjustable system, which allows the user to customize the height by adding or removing layers. These adjustable lifts provide a range of compensation to match various boot heights.
Another option is a simpler, non-adjustable lift that offers a fixed height, often secured with rubber straps or a hook-and-loop system. These levelers are designed with a non-skid rubber outsole to enhance stability on the shoe. Purpose-built levelers are preferred over improvised solutions like stacking insoles due to their secure attachment and stable, non-slip base.
Proper Height Matching and Usage
The most straightforward method for determining the required lift height is to measure the distance from the floor to the base of the walking boot’s sole. This measurement should be taken at both the heel and the forefoot to account for the boot’s rocker bottom design. The difference between the boot height and the height of the regular shoe on the opposite foot is the approximate lift needed to restore alignment.
The lift should be securely fastened to a closed-toe shoe or athletic sneaker on the uninjured foot, ensuring the straps prevent slipping. It is sometimes recommended to slightly under-compensate the height for comfort, as a perfect match may introduce minor new asymmetries. Patients should test the lift for stability and adjust it as needed. It is advisable to consult with a healthcare professional, such as a physical therapist or orthopedic specialist, for precise guidance on sizing and use. If pain in the back, hips, or knees persists despite using a lift, professional evaluation is warranted.