Most people haven’t heard of Helbing’s sign in the foot – and frankly that’s okay. It’s a clinical observation not a term that patients know. But if someone has told you your Achilles bows inward when you stand, or if a podiatrist has made a comment about the shape of your heel cord when examining your foot there’s a high probability Helbing’s sign in the foot has been mentioned.
This article describes what the sign actually is, why it occurs, how clinicians can test for it and what the result really indicates about foot health. You don’t need to be a healthcare professional to understand this article.
What Helbing’s Sign in the Foot Is
Helbing’s sign in the foot is a particular visual observation made on the posterior aspect of the lower leg and heel. A standing patient supporting weight fully will usually show a relatively straight vertical line from the heel to the Achilles, when the apparent line of the Achilles will bow medially toward the center of the body- the positive Helbing’s sign.
How It Looks on Examination
The hallmark of the Helbing sign is its evident medial bowing of the Achilles tendon. With the patient in a relaxed weight bearing position, the examiner views from a posterior perspective, the lower leg and heel. When the foot is in a normal, neutral position the Achilles tendon is directed, in a fairly straight or near straight path from the gastrocnemius muscle belly down to the calcaneus.
When Helbing’s sign is positive the course of the Achilles bow is directed inward, or a soft bend to the inside of the leg. (This will vary with severity of the pronation/pronation components of the foot mechanics).
Why Helbing’s Sign in the Foot Happens
The sign is not so randomly. It translates to what is occurring further down the foot ie a change in the angle of the heel and arch during weight bearing. As the foot pronates and the heel tilts outwards the heel attachment for the Achilles tendon moves and the Achilles adapts and follows that movement into its characteristic inward curve.
A knowledge of the sequence of the mechanical chain is quite helpful in understanding why this occurs more commonly in some foot types than others.
Flat Feet and Pronation
The relevance of Helbing’s sign to pes planus is uncontroversial and well known in the literature. With an absent or fallen arch, the calcaneus will tend to evert, moving on its axis such that the bottom of the Achilles tendon is pulled outward laterally at its point of insertion, while the upper portion remains relatively fixed and produces that inward bow that is observable from behind. Excessive pronation of the foot produces a similar effect and it is the position of the calcaneus that produces the appearance of the tendon’s Bowstringing rather than the shape of the tendon.
Why It Is Not a Standalone Diagnosis
Here’s the hitch – Helbing’s sign indicates something to you, but not all that. It is one piece of data. A person could have a positive sign, yet have no pain, no functional limitation, no significant flat foot.
Another person with a relatively low arch may not get the sign. The observation doesn’t measure arch height, the range of motion of the joints or the strength of the muscles, just as a diagnostic. It is merely a beginning, not an end.
It is not a diagnosis, anything more would be silly, most of today’s podiatrists know that.
How Clinicians Assess It
Assessment of Helbing’s sign is relatively simple, and that is what makes it desirable in practice. There is no need for imaging, no expensive machinery, and no discomfort to the patient. The examination itself is quick.
However, there should not be a reliance on this examination alone. An astute clinician will use the observation, once made, as the beginning of an overall assessment of the foot posture, gait, and other factors that contribute to the presentation.
Visual Observation From Behind
The usual procedure is to have the patient stand barefoot with both feet flat on the ground and about the width of the hips apart, in their normal resting position. The examiner then crouches (or stands if they prefer) behind the patient so they can observe the Achilles tendons from the front with both visible at once. It can be of benefit to compare the high and low side of both tendons (so take the left and right Achilles into account too, as this may be as relevant as the bowing itself).
Some practitioners use a plumb line or grid mat to place the deformity in context but these are not always necessary, and some people may argue that trained eye observation is adequate.
Related Foot Posture Findings
Although Helbing’s sign is said to rarely present in isolation, clinicians are more likely to evaluate the calcaneus simultaneously by observing if the heel is in varus or valgus. Further examination of the foot includes the assessment of the forefoot, navicular drop and arch height, which work synergistically with one another to contribute to a comprehensive assessment of the foot’s mechanics. For instance, the presence of Helbing’s sign in conjunction with the observation of a laterally everted calcaneus and a dropped navicular, provides a more conclusive indication of a pronated foot than would otherwise be possible.
What It Means for Foot Health
The clinical significance of Helbing’s sign, then, is highly context-dependent. It may be meaningful in a symptomatic individual who has heel pain, plantar fasciitis, or posterior tibial tendon pain, and the sign may lend support to a mechanical aetiology. However, in an entirely asymptomatic individual, it may have no significance other than that it is the way their foot has always been.
When It May Matter Clinically
It is when Helbing’s sign is experienced in combination with other signs and symptoms that leads are made in the treatment of a condition. As previously discussed, over-pronation and calcaneal eversion significantly burden the medial structures of the foot and ankle and in combination with other signs orthotic therapy, strengthened activation of the posterior tibial muscle and footwear modifications could all be appropriate treatments if the sign contributes to a symptomatic pattern.
Limits of Clinical Usefulness
Some sources do state that Helbing’s sign has limited clinical utility in isolation—and this is a reasonable conclusion. The evidence for inter- and intraobserver reliability of visual assessment of a tendinous arch in vivo is inconclusive and this sign does not match perfectly with arch measurements on X-ray or functional ability. It is most useful in the context of a screening test that prompts further questioning.
Common Questions and Misunderstandings
Is Helbing’s Sign the Same as Flatfoot?
No – and it’s important. Helbing’s sign is just visually observing and palpating the position of the tendons, it does not necessarily define what a flatfoot is. Pes planus (flatfoot) is an umbrella term that refers to the structure of the arch, the mechanics of the joints in the foot and sometimes the symptoms the person experiences.
It is possible to have flat feet yet not have a positive sign as well as the sign occuring in a foot that is not essentially flat.
Who Was Helbing?
Carl Helbing was a German physician in the late 19 th century. The sign that bears his eponym is in fact based on his initial report of this deviation of the tendons as a clinical sign for deformity of the foot. However, as with many eponyms from that time period, the clinical finding has been modified and redefined, and his eponym remains attached.