Heel lifts function by raising the calcaneus (heel bone) relative to the ground, thereby altering the alignment and loading characteristics of the entire lower kinetic chain. This adjustment can influence everything from foot-strike mechanics and ankle kinematics to proximal structures like the knee, hip, and lumbar spine. While seemingly elementary, the precise application of heel lifts requires a nuanced understanding of their specific biomechanical effects. This essay will detail the primary mechanisms by which heel lifts operate, explore their clinical applications in treating common foot problems such as leg length discrepancy, Achilles tendinopathy, and plantar fasciitis, and address the necessary considerations and potential drawbacks associated with their use.
Biomechanical Principles and Mechanisms of Action
A heel lift primarily acts by inducing a change in the static and dynamic relationship of the lower extremity joints. Mechanically, raising the heel effectively places the ankle joint in a greater degree of plantarflexion. This has two immediate consequences: first, it reduces the necessary range of ankle dorsiflexion required during the stance phase of gait; and second, it translates the ground reaction force vector, subtly altering the moments acting on the knee and hip.
The primary objective is often to mitigate abnormal stress or strain placed on soft tissues. By reducing the required excursion of the ankle joint, tension is immediately eased in the posterior muscular structures—specifically the gastrocnemius and soleus muscles (the triceps surae) and the associated Achilles tendon. This is critical in managing overuse injuries. Furthermore, the proximal effects are equally important: in cases of structural asymmetry, a heel lift can correct pelvic obliquity and reduce asymmetrical loading patterns through the hip and spine, addressing a common cause of chronic low back pain or recurrent functional scoliosis. The precise height and contour of the lift are therefore paramount to achieving the desired therapeutic effect without introducing new, compensatory pathological patterns.
Application in Leg Length Discrepancy (LLD)
One of the most common and robust clinical indications for heel lift therapy is the management of leg length discrepancy (LLD), where one lower limb is physically shorter than the other. LLD can be categorized as either structural (due to actual bone length difference, often post-trauma or congenital) or functional (due to soft tissue contracture, joint malalignment, or pelvic rotation). Uncorrected LLD forces the body to adopt compensatory mechanisms, including early heel rise, excessive knee flexion on the longer side, and ipsilateral pelvic drop, leading to pain in the foot, ankle, knee, hip, and lumbar spine.
The goal of using a heel lift in LLD is to restore a more level pelvic alignment in the frontal plane. The lift is placed under the heel of the anatomically shorter limb. However, full correction to the measured discrepancy height is rarely advised immediately. Clinical practice dictates a gradual increase in lift height to allow the body’s neuromusculoskeletal system to adapt, often starting with fifty to seventy-five percent of the measured difference, with increments added over time until symptoms resolve and postural alignment improves. Lifts greater than 12 millimeters, particularly if used in conjunction with physical therapy and manual adjustments, are typically more effective when the lift extends the full length of the shoe (a full-length insole) to ensure even pressure distribution and prevent forefoot strain. Accurate measurement, often via radiographic study (scanogram or orthoroentgenogram) or clinical methods, is essential for successful, personalized treatment.
Application in Achilles Tendinopathy and Plantar Fasciitis
Heel lifts play a significant, though often temporary, role in the acute management of lower leg and foot soft tissue injuries, notably Achilles tendinopathy and plantar fasciitis.
Achilles tendinopathy involves degeneration and irritation of the Achilles tendon, often caused by repetitive strain or sudden increases in activity. By placing the heel in a slightly elevated position, the tension and load on the Achilles tendon are reduced, especially during the terminal stance and toe-off phases of the gait cycle. This mechanical offloading provides a crucial period of relative rest, allowing microtrauma repair and reducing inflammatory pain. Similarly, in the case of plantar fasciitis—inflammation of the thick band of tissue spanning the bottom of the foot—heel elevation provides a degree of relaxation to the triceps surae, which can be linked to fascial tension. Furthermore, the heel lift often acts as a cushion, mitigating the impact shock that directly irritates the calcaneal insertion point of the fascia. It is critical to note that for these tendinopathies, heel lifts are generally a part of a multimodal treatment plan. They are often used alongside non-steroidal anti-inflammatory drugs (NSAIDs), stretching, and eccentric strengthening protocols, and are typically weaned off once the acute pain subsides to prevent the permanent shortening of the Achilles tendon complex.
Application in Other Musculoskeletal Issues
Beyond LLD and common tendinopathies, heel lifts are sometimes employed to address other specific foot and ankle structural issues. For patients suffering from Haglund’s deformity, a bony enlargement on the back of the heel where the Achilles tendon attaches, a soft heel lift can elevate the heel out of the back of a rigid shoe counter. This reduces direct mechanical friction and pressure on the sensitive bursa and bony prominence, providing symptomatic relief. In cases of certain forefoot pathologies, such as metatarsalgia (pain in the ball of the foot) or forefoot ulcers, a heel lift can subtly shift the center of pressure rearward during the gait cycle. By increasing the load placed on the midfoot and hindfoot, the lift temporarily decreases the damaging pressure exerted on the painful forefoot structures, aiding in the healing process or management of chronic pain.
Risks, Limitations, and Professional Guidance
Despite their benefits, heel lifts are not without limitations and potential risks. The most significant risk, especially with long-term, unmonitored use, is the permanent shortening and tightening of the triceps surae muscle group. If the Achilles tendon complex constantly operates in a shortened state due to chronic elevation, the natural range of dorsiflexion can decrease, potentially leading to chronic gait abnormalities or increased susceptibility to injury if the lift is removed. Furthermore, improperly sized or unilaterally applied lifts can introduce new compensatory issues higher up the kinetic chain, particularly knee hyperextension or altered hip mechanics, leading to secondary pain. Therefore, a heel lift should never be considered a standalone, definitive treatment. Proper implementation requires a thorough assessment by a healthcare professional, such as a physical therapist, orthopedist, or podiatrist, who can accurately diagnose the underlying condition, determine the optimal lift height, and integrate the lift into a holistic regimen involving stretching, strengthening, and manual therapy. The ultimate therapeutic goal is always the restoration of normal, symmetrical biomechanics, often leading to the eventual cessation or reduction of heel lift dependence.
Heel lifts are a versatile and cost-effective tool within the orthopedic arsenal, primarily utilized to modulate lower limb mechanics for pain reduction and improved function. Their clinical utility is broad, ranging from correcting the asymmetrical loading caused by leg length discrepancy to providing critical mechanical offloading for inflamed soft tissues like the Achilles tendon and plantar fascia. The mechanism, whether through reducing dorsiflexion requirements or restoring pelvic alignment, focuses on mitigating pathological strain. However, the successful integration of heel lifts hinges on accurate diagnosis, meticulous sizing, and a clear exit strategy managed by a qualified professional. When utilized judiciously and as part of a comprehensive rehabilitation plan, heel lifts offer an effective, non-invasive pathway toward improved musculoskeletal health and reduced pain for a variety of lower extremity conditions.