WHAT IS SEVER’S DISEASE/SYNDROME?
Sever’s disease is a common source of activity-related heel pain in children and early adolescents, usually occurring between the ages of 9-13. It causes pain during and after exercise and tends to go away after any period of rest. However, it can hurt again when weight is initially loaded onto it for a little while after exercise.
Although the actual cause of the pain remains a bit of a mystery, the problem seems to relate to high levels of stress associated with frequent periods of high activity on an immature, growing heel bone. Usually, this relates to increasing training sessions associated with multidirectional sports such as football (soccer), rugby, and hockey.
The most common sites of Sever’s pain are around the sides and back of the heel as well as a little underneath it. Squeezing around the heel often provokes discomfort.
Growing Bones of the Heel
The scientific name of the heel bone is the calcaneus. It sits under the ankle bone (talus). The heel bone is an important weight-bearing bone, for it is the first part of the foot that makes ground contact during walking, and at most slower running speeds. As a result, it is covered in special fatty padding underneath it, lying above the heel’s skin. This links to fatty tissue in the forefoot via a strong band of tissue called the plantar fascia or aponeurosis.
The heel bone also provides important attachment points for some of the bigger muscles that lie under the foot. Also attached to it are some extremely important ligaments that support the foot’s shape and function during walking. The strong but elastic fibrous plantar fascia also runs from the underside heel bone towards all the toe joints. In adults, the plantar fascia is a common source of heel pain, known as plantar fasciitis. However, this condition does not normally affect children.
The Achilles tendon also attaches to the heel bone on its back edge. Linked to the powerful calf muscles, the Achilles tendon is the biggest tendon found in humans. It is used to store and release power from the calf muscles generated during locomotion. By doing this, it provides lots of power to the back of the heel bone to allow humans to accelerate off one foot and onto the next step. Because humans grow much taller from infancy to adulthood, it is essential that the heel bone not only gets bigger but becomes longer throughout childhood.
Bone does not grow very rapidly, so during childhood many bones have a lot of cartilage near the joints to allow bones to grow longer before they achieve their adult lengths. This is true of all long bones like the thigh bone (femur), and leg bones (tibia and fibula). More squat-like bones (short bones) like the heel and ankle bones do something a little different. They have a central area of bone, surrounded by fast-growing cartilage that can be turned into bone afterwards. This is great for making bone bigger, but not so good for making bone longer. The heel bone needs to become bigger and become longer. It overcomes the problem by having a second area of bone forming at the back of the heel bone, and a bigger one in the middle. Cartilage can grow quickly between the two areas of bone to increase the length of the heel bone, and then turn it all into bone later.
The clever bit is that the amount of tension developed by the Achilles attaching to the back of the heel and the important structure under the heel attaching to the forefoot, dictates how long the calcaneus becomes, so that length reflects the forces on the heel during growth. This secondary bone area starts to form around age seven, which is just when walking starts to become more adult-like. Slowly the two areas of bone grow towards each other, to finally fuse together during late teenage years. At this time, the length of the heel bone cannot change significantly anymore.
The Immature Heel Bone Issue
The anatomy around the heel bone is therefore different between children and adults. Not only is the heel bone composed of a lot of cartilage and consists of two separate areas of growing bone, but there are fibres of tough connective tissue continuous between the Achilles and the plantar fascia running around the back of the heel. These fibres start to disappear once the heel bone is fused and have fully atrophied away by our late twenties.
This means a child’s heel bone can experience somewhat different stresses from an adult’s. If excessive, they might cause Sever’s. The first issue is that as the two areas of stiffer bone come close together, the more flexible cartilage can start to be sheared between the two bone areas. The stresses on the Achilles and the muscles, ligaments, and plantar fascia on the heel can start to pull in opposite directions, torquing the growing cartilage between the bone and thereby irritating the nerve fibres in the local area. This might explain why multidirectional sports more commonly cause Sever’s than do running sports like athletics.
Another potential cause is the growing bone itself, which is not as strong or as well formed as adult bone. Motion within the secondary bone in the back of the heel may receive excess torque motion directly across it or high tensions from the Achilles and other soft tissue under the foot that the immature bone can not cope with. Alternatively, because fibres run over and under the back of the heel between the Achilles and plantar fascia, when the calf and foot muscles contract the immature bone at the back of the heel may become overly compressed. In truth, it is most likely that variable combinations of these problems cause the pain associated with Sever’s.
The top image shows the immature heel with a growth plate (green area) dividing the heel bone into two. Fibres run over and under the back of the heel between the Achilles tendon and the plantar fascia. When the Achilles and plantar fascia become tightest just before and during heel lift, the growth plate can become over-stressed. In adults (lower image), the Achilles and plantar fascia attach separately to the mature heel bone, so injuries tend to form within the Achilles and plantar fascia, not within the heel bone.
Treating Sever’s
The good news is that Sever’s usually responds well to the correct treatments. Most cases require the forces around the heel bone to be altered for a while. This can be achieved by increasing the muscle strength and flexibility under the foot and within the calf.
Recommended Exercises:
Foot Therapy Ball Exercise
Stair Exercise
Heel Raise Exercise
Toe Motion Exercises
Lifting the heel and adding foot support around the heel, across the arch and under the forefoot can make a huge difference to pain. Insoles, such as the pedipod that are designed specifically for the requirements of children and younger adolescent foot are ideal. The X-Line TPD50 is the perfect option for larger adolescent feet ( sizes over adult 6).
It might also be wise to reduce the level of sport for a while until the pain has resolved.
Try reducing activity by 50% at first and see if this allows the symptoms to settle. If this still brings on discomfort, drop to 25% or take a complete rest for a month. Once symptoms have resolved, always bring activity levels back up gradually by only around 10% per week.
If symptoms start again, drop back to the previous level of activity that was asymptomatic, and try to increase again after another week. If your child plays competitively, it might be wise to only come on as a substitute player in the second half of a game. Try and avoid playing the first half because if your child is playing well, the temptation is to keep them on. That might just get the heel irritated again.
If a game/event seems to be really important, then as a last resort you can try strapping the heel. This has proven very effective at reducing symptoms, even during/after higher levels of activity. However, we do recommend a break from higher activities for a little while as the fastest way to resolve Sever’s.
For more on taping/strapping, watch the video below.
PLEASE NOTE:
Although most childhood/adolescent heel pain is caused by Sever’s, there are several other causes of heel pain. Sever’s causes pain during and after exercise and tends to go way after a period of rest, until weight is loaded onto it again.
The symptom to be most concerned by is night pain in the heel or developing in any other limb area. Because children’s bones are rapidly growing, sometimes mutations can occur within the bone or cartilage cells. These can very rarely cause bone/cartilage cancers. Although most are benign, all require urgent treatment because they can damage the limbs/foot’s anatomy. Very rarely, such cancers are malignant and very dangerous unless treated right way.
Therefore, if your child develops night pain deep within specific areas of the arms, legs, and feet at night you should seek a medical/clinical opinion quickly to rule out anything serious.