Heel Rocker

HealthyStep’s heel rockers are 6-7mm thick (depending on size) in the middle but angled in the sagittal plane at 12º posteriorly behind the arrow and at 10º anterior to the arrow, to help reduce ankle stresses during gait.

The unique proximal angulation chosen is designed to delay the rate of the plantarflexion moment applied after initial contact and reduce the total range of ankle motion necessary to complete forefoot loading. 

The central raised plateau reduces the amount of ankle dorsiflexion required during late midstance to move body weight forward over the midfoot. 

The distal inferior angulation is designed to accelerate weight transfer to the forefoot at the heel lift boundary, making it easier to lift the heel and accelerate from the forefoot.

These heel rockers have a selected shore hardness that provides some shock absorption to counter the loss of ankle motion, which decreases the rearfoot’s ability to act as a shock attenuator. Also, patients with ankle osteoarthritis are likely to require these heel rockers, and they will have lost their natural ankle shock-absorbing properties.

During heel contact, the posterior heel strikes the ground first. Because this initial ground impact is behind the ankle (more so with longer strides), ground reaction forces (GRF) cause the ankle to rotate into plantarflexion. This motion brings the forefoot to the ground. This is often referred to as the ‘heel rocker,’ although motion ‘really’ occurs at the ankle (star). During midstance, the so-called ‘ankle rocker’ motion is caused by ankle dorsiflexion, allowing the body weight to rotate forward over the foot. At heel lift, it is often suggested that a ‘forefoot’ rocker is used. Indeed, the metatarsophalangeal joints become the pivot points to rotate the foot over the toes, but significant ankle plantarflexion is also required with some midfoot plantarflexion. The ankle plays a huge and important part in healthy motion during gait.

In patients who have lost their full range of ankle plantarflexion motion, this is a considerable issue that can only be solved by dramatically reducing the stride length. Effectively, these individuals attempt to walk with a total plantar heel or even whole plantar foot initial contact. This adjustment to gait requires changes in all other lower limb joint angles and body posture, reducing locomotion energetics and tiring the patient. However, not making these changes can cause further ankle joint damage.

By having a skived posterior aspect on a heel lift, stride length can be maintained to a greater extent, while the plantarflexion toque and motion are lowered. This reduces how much the ankle must move into plantarflexion and yet still achieves a more efficient and stable ankle joint and body posture. Added to this, the TPU material’s shock attenuation during rearfoot loading and early midstance can help protect internal ankle mechanics.

The central platform of the addition is 6-7mm thick. This heel height decreases how much ankle dorsiflexion is required before body weight has sufficiently moved forward over the foot to initiate a safe heel lift. The concurrent benefit of doing this is that the midfoot dorsiflexion stresses can be reduced.

Thus, a heel lift lowers stresses applied across the midfoot arising when limited ankle dorsiflexion blocks anterior body weight motion. A rocking-style heel lift therefore reduces midfoot pronation, and encourages higher metatarsal declination angles, making digital extension easier at the start of acceleration.

The heel rocker’s distal-angled skive allows a forward-rolling action from the rearfoot without requiring greater ankle dorsiflexion before heel lift. Working with the heel lift height, this addition can aid an effective acceleration moment without necessitating higher ranges of ankle plantarflexion after heel lift. 

For diabetics who suffer loss of ankle motion and peripheral neuropathy, the heel rocker effect can be very helpful in reducing the destructive forces that can create a Charcot foot. The insole chosen for use with the heel rocker, should reflect the other issues and the foot morphology of the diabetic patient.

The heel rocker can help to improve symptoms before rehabilitation and or manual therapy in many situations. A heel rocker added to an X-Line AT for symptomatic Achilles tendinopathy, can be highly beneficial, including for insertional cases. If there is an improvement in any underlying ankle restrictions or triceps surae-Achilles complex issues with therapy, the rocker can be removed later.

Degenerate articular changes dramatically alter ankle joint stresses. In those with severely restricted ankle motions due to extensive ankle degeneration or after ankle fusion, using an X-Line DJD in a rocker-soled shoe and adding the heel rocker plus a DJD enhanced forefoot rocker or met bar rocker additions, can prove most effective for improving gait energetics. This is an ideal combination used by leading experts in ankle degeneration caused by haemophilia, and it is also very helpful if a patient has both ankle and 1st MTP degeneration.