Sever Disease (Calcaneal Apophysitis)

Etiology

Sever disease is an overuse injury due to repetitive strain and microtrauma caused by the force of the strong Achilles tendon on the relatively soft calcaneal apophysis. The calcaneal bone can outpace muscle growth, and a shortened triceps surae directly correlates to the irritation of the apophysis.[7] After periods of rapid growth and increased activity, the force exerted by the Achilles tendon intensifies. 

Factors contributing to the risk of Sever disease include a high BMI, increased or excessive sports activity, limited ankle range of motion, poorly cushioned or worn-out athletic shoes, cleated athletic shoes, running on hard surfaces, and biomechanical factors such as genu varum, forefoot varus, overpronation, pes cavus, or pes planus.[8][9] The most prevalent sports associated with this condition involve repetitive running and jumping, including basketball, soccer, track, cross-country, and gymnastics.[2]

Sever disease is not generally associated with traumatic events; however, in rare cases, trauma may lead to a complete avulsion fracture.[10]

Epidemiology

Sever disease predominantly manifests during the rapid growth phase in active children and adolescents aged 8 to 15.[4][10][11] As one of the leading causes of heel pain in adolescents, Sever disease contributes to 2% to 16% of all musculoskeletal complaints in children.[8] Notably, it is common for symptoms of Sever disease to appear on one foot, but up to 60% of patients experience pain in both feet. Males are more likely to develop this condition, with a frequency of occurrence 2 to 3 times higher than in females. The typical age of onset is around 12 for males and 11 for females.[2][10][12]

Pathophysiology

The posterior calcaneus develops as a secondary ossification center that provides the attachment point for the Achilles tendon. During the early adolescent growth spurt, bone growth exceeds the ability of the muscle-tendon unit to stretch sufficiently to maintain previous flexibility. Consequently, increased tension is exerted across the unossified or incompletely ossified apophysis. The apophysis represents the most vulnerable point in the muscle-tendon-bone attachment, unlike the tendon in an adult. Therefore, the apophysis is susceptible to overuse injuries resulting from repetitive stress.

Repetitive and excessive traction exerted by the strong Achilles tendon leads to microtrauma and chronic irritation, resulting in thickening and pain at the apophysis.[12] Thus, the leading theory that attempts to explain the mechanism behind Sever disease relies on the ongoing shear stress and repetitive impact on the open calcaneal apophysis. A study aiming to quantify this mechanism reveals that peak plantar pressure reaches 880 kPa in patients with Sever disease compared to 88 kPa in healthy controls during walking.[10] Intuitively, the peak plantar pressure would further exacerbate during running and jumping, explaining the pain experienced by patients with Sever disease.   

History and Physical

The classic presentation of Sever disease involves an active child or adolescent aged 8 to 15 with unilateral or bilateral heel pain that intensifies during and after activity, particularly during running and jumping. The patient will often not recall a specific injury. However, the onset of pain will coincide with a recent growth spurt, a new sport or training, or the beginning of a sports season.[10] Pain typically alleviates with rest and is usually absent in the morning. With time, the pain may intensify, potentially leading to limitations in activity.

The physical examination should reveal no signs of erythema or ecchymosis, but there may be tenderness and mild swelling at the Achilles insertion on the heel. In addition, the physical examination may indicate pain with passive ankle dorsiflexion. Pain can be reproduced with manual medial and lateral compression of the posterior calcaneus and aggravated by standing on tiptoes—a phenomenon known as the Sever sign. Poor heel cord flexibility or dorsiflexion weakness may be observed as predisposing risk factors.[5][13] Upon gait examination, the patient may exhibit a limp or walk on their toes to avoid putting pressure on the affected heel.[1] 

Evaluation

Sever disease is primarily a clinical diagnosis; hence, the history and physical examination outlined above are typically adequate for diagnosis.   

If the presentation is atypical, severe, or persists after 4 to 8 weeks of conservative management, it is advisable to consider obtaining advanced imaging to rule out infection, neoplasm, or occult fracture. Plain radiographs often reveal sclerosis and widening of the growth plate. However, these changes can also be observed in normal variants.[14] When ordering radiographs, it is recommended to consider bilateral imaging to distinguish osseous abnormalities from normal variants in the individual patient.[5][13] MRI is more effective in differentiating between Sever disease, tumors, and infection.[4]

Laboratory findings typically fall within normal limits. Elevated inflammatory markers such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) may suggest osteomyelitis. In less than 50% of cases of calcaneal osteomyelitis, there is an elevated white blood cell count. However, CRP and ESR levels are elevated in up to 77% and 95% of cases, respectively.[15]

Treatment / Management

Sever disease is a self-limiting condition that resolves with maturation and closure of the apophysis.[11] The primary objective of the therapy is pain relief,[4] and there is no indication for operative management in Sever disease.

Limiting Participation in Painful Activities

Individuals should limit strenuous activity, especially running and jumping, and gradually resume participation when their symptoms resolve.[4] In some cases, patients may need to abstain from sports until symptoms subside temporarily.

Ice Application

Individuals should apply ice to the painful area for 20 minutes daily. Ice acts as a vasoconstrictor and reduces the flow of inflammatory cells to the affected area. When used with rest periods, ice aids in diminishing the inflammatory process.

Orthotic Use

Heel lifts, heel cups, and heel pads can reduce traction forces on the apophysis, thereby alleviating pain.[4] These are particularly beneficial in cleated shoes that may exacerbate symptoms by concentrating the impact force on the heel. Custom orthotics also represent a viable option.

Immobilization

Immobilization may be necessary if there is no improvement after 4 to 8 weeks, which involves periods of casting or using a CAM boot.[1][11]  

Nonsteroidal Anti-Inflammatory Drugs

In the acute stage, oral non-steroidal anti-inflammatory drugs (NSAIDs) can be utilized to reduce inflammation. However, it is advised not to use anti-inflammatory medications before physical activity to prolong the child's playtime with reduced or no pain. Although topical ketoprofen is effective, it is not recommended for children under 12.[11]

Braces

Braces can be beneficial for barefoot athletes, such as gymnasts and dancers, who cannot wear orthoses. Barefoot athletes with Sever disease using the Cheetah heel cup and X-brace exhibit significantly decreased visual analog scores (VAS) and sports improvement at 2 and 3 months.[8]

Kinesiotherapy and Taping

Limited evidence supports kinesiology taping; however, affected patients report immediate relief. The taping technique regulates blood flow, eliminates inflammatory cytokines, and reduces tension and stress in the affected area.[10]

Stretching and Exercises            

Calf stretches can alleviate the discomfort of the Achilles tendon pulling on the posterior calcaneus.[1] Exercising to strengthen adjacent muscles can also reduce the workload on the Achilles tendon.[1] 

Physical Therapy

Physical therapy includes calf-muscle stretching, strengthening exercises, ultrasound, and possibly electrical stimulation.[10] In cases where a patient does not show improvement with a home stretching program, the involvement of a physical therapist becomes necessary. 

A study comparing rest, orthoses, and physical therapy in treating Sever disease demonstrated a significant decrease in pain with all modalities, with no statistically significant difference between them for pain reduction.

The primary treatment for Sever disease typically involves heel cups, rest, ice, calf stretching and strengthening, and NSAIDs. Severe cases or those unresponsive to physical therapy and other conservative measures may require immobilization using a CAM boot or casting. Orthoses are beneficial when biomechanical factors, such as overpronation, are present. Furthermore, it is essential to maintain well-fitted and up-to-date footwear. Braces can be advantageous for individuals engaged in barefoot activities. 

Symptoms typically resolve within a few weeks to months, and Sever disease is generally self-limited. Although recurrence may occur, particularly during periods of increased activity, it will not persist after apophyseal closure. Injection therapy or surgical intervention does not play a role in the management of Sever disease.  

Differential Diagnosis

Several conditions may present similarly to Sever disease. Therefore, to properly distinguish between these conditions, it is crucial to conduct a complete medical history and a detailed physical examination.[6] As mentioned earlier, advanced imaging should be ordered for atypical, severe, or persistent presentations. Although most conditions are easily identifiable through MRI, calcaneal fractures and tarsal coalitions can be excluded with plain radiographs.[4][14] 

The various conditions that share clinical features with Sever disease and necessitate a careful evaluation for accurate diagnosis include Achilles tendon rupture, Achilles tendonitis, retrocalcaneal bursitis, calcaneus fractures, calcaneal cysts, osteomyelitis, tarsal coalition, plantar fasciitis, heel contusion, posterior ankle impingement, and bone tumors.

Prognosis

Although the recurrence of Sever disease is relatively common, symptoms are typically anticipated to resolve after the closure of the apophysis. Symptoms should not be expected to persist after the patient reaches skeletal maturity.

Complications

Individuals with Sever disease may concurrently experience Achilles tendonitis and plantar fasciitis. The sole documented complication associated with Sever disease is osteomyelitis, as evidenced by a limited number of case reports in the literature. In cases where osteomyelitis is suspected, an MRI should be promptly ordered for a thorough assessment. The recommended course of treatment involves a 6-week antibiotic regimen, leading to the resolution of the infection and subsequent improvement in symptoms.[15][16]