Iselin Disease Fifth Metatarsal Apophysitis | DPM

What Is Iselin’s Disease?

Iselin’s disease is traction apophysitis of the apophysis (secondary ossification center) at the base of the fifth metatarsal — the bony prominence on the outer side of the mid-foot. It is the pediatric equivalent of Sever’s disease at the heel, occurring during the same period of skeletal growth when the peroneus brevis tendon exerts traction stress on the unfused growth plate. The condition is named after Hubert Iselin, who described it in 1912. It occurs most commonly in children aged 8–13 who are involved in high-activity sports like soccer, gymnastics, basketball, and track.

Why Does Iselin’s Disease Occur?

During childhood growth, the apophysis at the fifth metatarsal base is a secondary ossification center that is not yet fused to the main metatarsal body. The peroneus brevis tendon inserts directly onto this apophysis. Repetitive traction from the peroneus brevis during activities involving running, jumping, cutting, and foot inversion creates traction stress that exceeds the apophysis’ healing capacity during rapid growth phases — resulting in inflammation, microtrauma, and pain at the growth plate. Tight peroneal muscles and cavovarus (high arch) foot type increase the traction force at the 5th metatarsal base, predisposing to Iselin’s disease.

Symptoms

Iselin’s disease presents with pain, tenderness, and swelling directly over the lateral aspect of the fifth metatarsal base — the bony bump on the outer side of the mid-foot. Pain worsens with running, jumping, and lateral movements; it improves with rest. An antalgic gait is common in more symptomatic children. The lateral mid-foot area is tender to palpation directly over the apophysis, and inversion stress of the foot (which loads the peroneus brevis) may reproduce pain. Bilateral involvement can occur. The growth plate apophysis is normal and easily visible on X-ray — distinguishing Iselin’s disease from the more serious Jones fracture and avulsion fracture.

Diagnosis: Distinguishing from Fracture

The critical diagnostic distinction is between Iselin’s disease and actual fractures at the fifth metatarsal base — namely avulsion fractures (where the apophysis is acutely pulled off) and Jones fractures (at the metaphyseal-diaphyseal junction). X-rays are essential: in Iselin’s disease, the apophysis is intact, parallel to the metatarsal shaft, and the growth plate is smooth and regular. Avulsion fractures show an acute transverse fracture through the apophysis; Jones fractures are at the proximal diaphysis perpendicular to the shaft. In uncertain cases, MRI characterizes the apophysis more accurately. Clinical context — insidious onset vs. acute injury mechanism — also guides interpretation.

Treatment

Iselin’s disease is treated conservatively with excellent results. Activity modification to reduce running and jumping loads is the primary intervention. Arch orthotics with lateral heel posting reduce the inversion moment that stresses the peroneus brevis attachment. Peroneal muscle stretching and strengthening address the underlying muscular tightness. Ice and NSAIDs manage acute pain. For more symptomatic children with significant activity limitations, short-leg walking boot immobilization for 4–6 weeks dramatically reduces symptoms by resting the growth plate. Return to sport is gradual after symptom resolution, with continued orthotic use until the apophysis fuses (typically by age 14–16).

Prognosis

Iselin’s disease is self-limiting — the apophysis fuses to the fifth metatarsal body by mid-adolescence, and the condition resolves permanently once fusion is complete. Long-term sequelae are rare. The primary management goal is pain relief and functional maintenance during the symptomatic period, which typically spans several months to 1–2 years depending on the child’s growth phase. Parents should be counseled that symptoms may recur with activity spikes during rapid growth phases and that this is normal — requiring temporary activity modification rather than alarm.

Why Michigan Families Choose Dr. Tom Biernacki for Pediatric Foot Conditions

Pediatric foot apophysitis conditions — Sever’s disease, Iselin’s disease, and Kohler disease — require a podiatrist who understands both the biomechanics of growing feet and the context of youth sports participation. Dr. Biernacki provides accurate diagnosis (importantly distinguishing apophysitis from fractures), evidence-based conservative management, and parent-friendly education about the natural history and what to expect. Michigan youth athletes treated at Balance Foot & Ankle return to their sports with confidence and appropriate protection.

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Frequently Asked Questions

What causes this condition?

Causes include mechanical stress, biomechanical imbalance, age-related changes, and sometimes systemic disease. Our clinical exam plus imaging identifies the specific driver.

Can it go away on its own?

Mild cases sometimes resolve with rest and supportive footwear. Persistent symptoms past 4-6 weeks rarely resolve without active treatment.

Is surgery required?

Most patients resolve with non-surgical care. Surgery is reserved for refractory cases or structural deformity.

Visit Balance Foot & Ankle — Same-Day Appointments Available

Our podiatry team serves patients throughout Michigan including Howell, Brighton, and Bloomfield Hills. If you’re dealing with heel pain, ingrown toenails, or a foot injury, we have same-day appointment availability.