Iselin Disease in Kids 2026 | Podiatrist

Iselin disease is apophysitis (growth plate inflammation) of the 5th metatarsal base in children and adolescents — it is the fifth metatarsal equivalent of Sever's disease (calcaneal apophysitis) and produces lateral midfoot pain that is often mistaken for an ankle sprain or 5th metatarsal fracture. The anatomy of Iselin disease: the 5th metatarsal base has a secondary ossification center (apophysis) at its lateral prominence — the bony attachment point for the peroneus brevis tendon; this growth plate appears on X-ray between ages 8–12 in girls and 10–14 in boys; during the adolescent growth spurt, the long bones lengthen rapidly; the peroneus brevis tendon, which inserts on the 5th metatarsal apophysis, becomes relatively tight as the bone lengthens; the tight tendon transmits repetitive tensile stress to the growth plate with every step and every ankle inversion/eversion movement; the result is inflammation, microtrauma, and pain at the apophysis. Who develops Iselin disease: it is an active child's condition — athletes in sports involving lateral cutting (soccer, basketball, gymnastics, dance, football) have the highest incidence; the lateral ankle inversion mechanism of cutting and pivoting maximally loads the peroneus brevis and its 5th metatarsal attachment; the condition peaks at the onset of the adolescent growth spurt — girls 8–12 years and boys 10–14 years; boys and girls are affected equally; bilateral involvement occurs in approximately 30% of cases (both feet simultaneously or sequentially). Why it is frequently misdiagnosed: Iselin disease presents with lateral foot pain at the base of the 5th metatarsal — exactly the location of 5th metatarsal avulsion fractures (a common injury in ankle sprains); many children with Iselin disease are diagnosed as having an ankle sprain or a 5th metatarsal stress fracture; the key distinction on X-ray: the apophysis of Iselin disease has smooth, corticated margins and runs parallel to the long axis of the metatarsal; a fracture has irregular, non-corticated margins and runs perpendicular to the long axis.

Iselin disease is a self-limiting condition — the apophysis reliably fuses and the condition resolves when the growth plate closes, so treatment is entirely focused on symptom management while awaiting natural resolution. Conservative treatment (the only management required): activity modification: the primary intervention; activities that maximally load the peroneus brevis (lateral cutting, jumping, pivoting) are reduced to pain-free levels; complete cessation of sport is rarely necessary and is not recommended for mild-moderate cases; reducing practice frequency and eliminating high-intensity agility drills during the most symptomatic phase allows continued sport participation; the child can typically maintain low-intensity participation (light jogging, swimming) during the restricted phase; peroneus brevis and calf stretching: addresses the relative tendon tightening that drives the condition; peroneal stretching: standing on a flat surface, invert the foot (sole pointing inward) and hold 30 seconds per side, 3 times daily; this stretches the peroneus brevis and reduces tension on its 5th metatarsal attachment; calf and Achilles stretching: reduces the overall posterior chain tension that contributes to lateral ankle loading; lateral heel wedge: a small lateral wedge (5–10mm) placed under the heel in the shoe slightly everts the rearfoot, reducing peroneal brevis tension at the 5th metatarsal; this is a simple, inexpensive, and effective symptomatic aid; cushion padding: a donut-shaped pad (foam or felt) with the center over the 5th metatarsal prominence reduces direct pressure on the painful apophysis in the shoe; NSAIDs: appropriate pediatric dosing of ibuprofen during painful flares; immobilization for severe cases: children with significant pain who cannot weight-bear comfortably may be managed with a short-leg walking boot for 3–4 weeks; this rapidly resolves the acute symptomatic phase. Prognosis: uniformly excellent; Iselin disease resolves completely when the growth plate closes; no long-term foot pathology results.

The 5th metatarsal base is the site of both Iselin disease (apophysitis in children) and several important fracture types — the distinction is critical because fractures require different management (including potential non-weight-bearing and surgery) while Iselin disease requires only conservative management. The key radiographic distinction: Iselin disease apophysis: the secondary ossification center at the 5th metatarsal base appears as a separate bone fragment with smooth, well-corticated margins; critically, the apophysis runs PARALLEL to the long axis of the 5th metatarsal; it is located along the lateral border of the metatarsal base; comparing to the opposite foot's X-ray often shows an identical appearance bilaterally, confirming the normal variant; 5th metatarsal avulsion fracture (the most common fracture at this location): caused by sudden inversion of the ankle where the peroneus brevis pulls off a fragment of bone; the fracture runs PERPENDICULAR to the long axis of the metatarsal (transverse); the fracture margins are irregular and non-corticated; occurs in all age groups (including children) but is a traumatic event rather than an insidious overuse condition; treatment: walking boot for 4–6 weeks for most avulsion fractures; 5th metatarsal Jones fracture (the 'fracture you cannot miss'): located in the proximal metatarsal shaft (not the base); 1.5cm or more distal to the base; runs transversely through the metadiaphyseal region; the Jones zone has poor blood supply and high non-union risk; management: non-weight-bearing in a cast for 6 weeks; surgical fixation (intramedullary screw) is preferred in athletes; clinical distinctions beyond imaging: Iselin disease: insidious onset over weeks in a growing child with no specific injury event; bilateral involvement in 30%; X-ray shows parallel orientation; 5th metatarsal avulsion fracture: typically follows a specific inversion ankle injury; unilateral; transverse fracture orientation on X-ray; Jones fracture: can be both traumatic and stress-related; located more distally than the avulsion/Iselin zone.

The timeline of Iselin disease parallels the child's growth plate maturation — understanding the natural history allows parents and coaches to set realistic expectations without unnecessarily restricting activities or prematurely returning to full intensity. Natural history and duration: the condition is present and symptomatic while the growth plate is open and being stressed by the peroneus brevis tendon; symptoms typically begin at the onset of the growth spurt (peak incidence 8–12 in girls, 10–14 in boys) and may persist episodically for 1–3 years; the condition resolves permanently when the apophysis fuses to the 5th metatarsal during skeletal maturation; this fusion occurs at approximately age 12–14 in girls and 14–16 in boys; once fused, the condition cannot recur; within each symptomatic episode, the acute pain phase typically resolves in 2–6 weeks with activity modification and symptomatic management. Return-to-sport guidance: during the acute symptomatic phase (1–2 weeks following onset or flare): high-intensity lateral cutting, pivoting, and jumping sports are restricted; swimming, cycling, and straight-line running are appropriate alternatives; the child can continue to participate in non-provocative team activities (team meetings, non-contact drills); return to full sport participation: most children return to full sport within 4–8 weeks of initial presentation with appropriate management; the return should be guided by symptom resolution rather than calendar time — the child is ready when lateral cutting and jumping activities are pain-free; gradual return (beginning with straight-line jogging, progressing to lateral drills, then full contact play) reduces the risk of recurrence at initial return; long-term: no documented effect on long-term athletic performance; no evidence that playing through mild Iselin disease causes permanent damage; the goal is to manage symptoms to a tolerable level while the growth plate naturally matures.