Sever Disease (Calcaneal Apophysitis)

== Epidemiology ==
It is one of the most common causes of heel pain in active children. It is usually seen in active young children that are involved in jumping and running. The mean age of presentation is 8-12 years. Boys are more commonly affected than girls. In up to 2/3rds of cases both heels are involved.
== Pathology ==
An apophysis is a growth plate that isn't involved in the linear growth of a bone. The calcaneal apophysis is found on the posterior inferior aspect of the calcaneus and is the growth plate at the insertion of the Achilles tendon. It develops earlier in girls (6) than boys (8). It is present for around 3-4 years in total. 
It has increased metabolic activity during rapid growth which predisposes it to overuse injuries. Certain activities increase the risk of injury especially any that involve running or jumping, or abnormal heel striking that places excessive traction on the apophysis by the Achilles tendon.
== Clinical Features ==
Patients complain of posterior heel pain that is aggravated by physical activity such as walking, running, or jumping. It has an insidious onset. There may be exacerbation when wearing footwear that doesn't have good heel cushioning such as jandals. Wearing soccer cleats can also provoke the poke because they centre the mechanical force onto the heel.
On exam there is tenderness over the apophysis. The calcaneal compression test is positive. In this test the examiner holds the heel in their palm with the fingers surrounding the upper part of the heel then they squeeze to compress the heel in the axial plane. This test is also positive in calcaneal contusion, stress fracture, and acute fracture. It should be negative in plantar fasciitis, fat pad syndrome, posterior impingement, and Achilles tendinopathy.
There may also be decreased calf flexibility, foot pronation, and abnormalities of the arch of the foot (pes planus or pes cavus). There may be a secondary Achilles tendinopathy or plantar fasciitis.
== Differential Diagnosis ==
== Imaging ==
The diagnosis is usually made clinically. 
Plain films are usually not required and may actually miss the problem. However they can be useful to exclude other disorders in atypical pain or if there is no improvement with rest. Typical findings are sclerosis and growth plate widening but they can also be seen in normal children.
Ultrasound can show asymmetrical thickening with or without retrocalcaneal bursitis. Apophyseal fragmentation may be visible. 
MRI can be considered if the plain films are normal but the patient has severe symptoms. In this context it can be helpful to exclude stress fracture.
== Treatment ==
Education: Advise that the pain is self limiting. They should decrease participation in painful activities and reintroduce them once symptoms have improved.
Heel cups: Bilateral heel cup should be considered to help manage pain with activities.Perhamre S, Lundin F, Norlin R, Klässbo M. Sever's injury; treat it with a heel cup: a randomized, crossover study with two insole alternatives. Scand J Med Sci Sports. 2011 Dec;21(6):e42-7. doi: 10.1111/j.1600-0838.2010.01140.x. Epub 2010 Jul 29. PMID: 20673253.Perhamre S, Janson S, Norlin R, Klässbo M. Sever's injury: treatment with insoles provides effective pain relief. Scand J Med Sci Sports. 2011 Dec;21(6):819-23. doi: 10.1111/j.1600-0838.2010.01051.x. Epub 2010 May 12. PMID: 20492591. Use a 5mm heel cup e.g. Tulis or KidZerts brand.
Strengthening: Advised to stretch and strengthen the calf muscles daily.
A separate trial compared wait and see versus heel raise inlay versus calf strengthening for 10 weeks and found no difference between groups with all resulting in improvement and satisfaction.Wiegerinck JI, Zwiers R, Sierevelt IN, van Weert HC, van Dijk CN, Struijs PA. Treatment of Calcaneal Apophysitis: Wait and See Versus Orthotic Device Versus Physical Therapy: A Pragmatic Therapeutic Randomized Clinical Trial. J Pediatr Orthop. 2016 Mar;36(2):152-7. doi: 10.1097/BPO.0000000000000417. PMID: 25985369.
Medication: NSAIDs can be used but not as a way to increase the amount of activity that is tolerated.
Refractory: In refractory cases (after excluding other conditions with MRI) you can consider using a short-leg cast or fracture boot with a rocker bottom sole for 3-4 weeks.
== References ==
Category:Foot and Ankle Conditions
Category:Developmental Disorders