Medically reviewed by Dr. Tom Biernacki, DPM — Board-Certified Podiatric Surgeon — Balance Foot & Ankle, Howell & Bloomfield Hills, MI. Last updated April 2026.

What Is Iselin’s Disease and Who Gets It?

Iselin’s disease is an overuse injury to the growth plate (apophysis) at the base of the fifth metatarsal, where the peroneus brevis muscle attaches via its tendon. During skeletal development, this growth center appears around age 8 and doesn’t fuse to the main bone until ages 12-14 in girls and 13-16 in boys. During this vulnerable window, repetitive traction from the peroneus brevis tendon during running, jumping, and lateral movements irritates the apophysis, causing pain and inflammation.

The condition belongs to the family of pediatric traction apophysitis — overuse injuries affecting growth plates where tendons attach. Sever’s disease (calcaneal apophysitis) at the heel and Osgood-Schlatter disease at the knee are better-known cousins. Iselin’s disease is less commonly diagnosed but likely underreported, as lateral foot pain in young athletes is frequently attributed to ankle sprains or generic ‘growing pains’ without specific evaluation of the fifth metatarsal base.

Risk factors include sudden increases in training volume (beginning of a new sport season), participation in cutting sports (basketball, soccer, tennis, football), rigid or poorly fitting athletic shoes that compress the lateral forefoot, and pronated foot type (which increases peroneus brevis activity as a compensatory stabilizer). A 2024 pediatric sports medicine study found that 80% of Iselin’s disease cases occurred during the first 4 weeks of a new competitive season when training volume increased sharply.

Recognizing Iselin’s Disease: Signs Parents Should Know

The hallmark symptom is pain along the outer edge of the foot at the base of the fifth metatarsal — specifically at the prominent bony bump (styloid process) that parents can feel on the lateral midfoot. Pain worsens with activity and improves with rest, a classic pattern for apophysitis. Children may limp after practice, refuse to play, or favor the inner edge of the foot to avoid pressure on the lateral side.

Physical examination reveals point tenderness directly over the fifth metatarsal styloid process, pain with resisted eversion (turning the foot outward against resistance), and often visible or palpable swelling along the lateral midfoot. The ankle joint itself is non-tender, which helps distinguish Iselin’s disease from the much more common ankle sprain — though both can coexist in young athletes who sustain inversion injuries.

X-rays show the apophysis as a separate bone fragment adjacent to the fifth metatarsal base, which can be confused with an avulsion fracture by practitioners unfamiliar with pediatric foot anatomy. The key distinguishing feature is that the normal Iselin apophysis runs parallel to the long axis of the metatarsal shaft, while an acute fracture line runs perpendicular. MRI is rarely needed but shows bone marrow edema within the apophysis in confirmed cases.

Treatment: Activity Modification and Protected Healing

Initial treatment focuses on reducing traction stress across the growth plate. Activity modification — temporarily stopping running, jumping, and cutting activities while allowing pain-free daily walking — is the first-line intervention. Most mild cases improve within 2-3 weeks of activity modification alone, without the need for immobilization. Ice application for 15-20 minutes after any weight-bearing activity reduces inflammation at the apophysis.

Moderate to severe cases (significant limp, tenderness with normal walking, or failed activity modification after 3 weeks) benefit from a short course of immobilization in a walking boot or supportive short leg cast. Immobilization for 2-4 weeks dramatically reduces symptoms by eliminating all traction forces on the apophysis. The boot or cast should extend past the toes to prevent any push-off loading through the lateral forefoot.

Dr. Tom Biernacki emphasizes that Iselin’s disease is a self-limiting condition that resolves once the growth plate fuses. The clinical goal is managing symptoms while the apophysis naturally incorporates into the mature fifth metatarsal bone. NSAIDs should be used judiciously — a short course (5-7 days) for acute pain is reasonable, but prolonged use in growing children should be discussed with the family. Physical therapy focusing on calf stretching, peroneal flexibility, and proprioceptive balance training supports return to activity.

Return-to-Sport Protocol for Young Athletes

A graduated return-to-sport protocol prevents recurrence and ensures the growth plate has adequate time to recover before resuming full loading. Phase 1 (weeks 1-2 after becoming pain-free): Walking normally, gentle stretching, and non-impact conditioning such as swimming or upper body strength training. Phase 2 (weeks 2-3): Light jogging on flat surfaces, beginning with 50% of normal training volume and duration.

Phase 3 (weeks 3-4): Progressive running with cutting and lateral movement introduction at 75% intensity. Phase 4 (week 4+): Full return to sport-specific training and competition. Each phase advancement requires the child to be completely pain-free during and after the previous phase’s activities. Any recurrence of lateral foot pain signals the need to step back one phase.

Parents and coaches should understand that Iselin’s disease recurs in approximately 20-30% of cases during the same growth period if return to sport is too aggressive. The growth plate remains vulnerable until complete fusion, so ongoing monitoring during subsequent sport seasons is important. Pre-season conditioning programs that gradually ramp up training intensity over 3-4 weeks rather than jumping directly into full competition significantly reduce recurrence risk.

Foundation Wellness Products for Pediatric Lateral Foot Pain

PowerStep Pinnacle insoles placed inside athletic shoes provide arch support and lateral forefoot cushioning that reduces traction stress on the fifth metatarsal apophysis. The semi-rigid shell prevents excessive pronation (which overloads the peroneus brevis), while the cushioned topcover absorbs impact during running and landing. Sizing down to youth sizes ensures proper fit in children’s athletic shoes.

Doctor Hoy’s Natural Pain Relief Gel offers a safe topical option for pediatric patients. Applied to the lateral midfoot before and after activity, the menthol and arnica formula provides localized pain relief without systemic absorption. This is preferable to oral NSAIDs in growing children where prolonged anti-inflammatory use raises concerns about growth plate health and GI tolerance.

CURREX SupportSTP insoles in youth sizes provide thin-profile support that fits inside cleats and sport-specific footwear where standard insoles may not fit. The flexible arch support reduces lateral foot loading during the cutting and pivoting motions that stress the fifth metatarsal apophysis. Combined with properly fitting shoes that provide adequate lateral support, these insoles create a protective environment during the return-to-sport phase.

Differential Diagnosis: What Else Could It Be?

Several conditions mimic Iselin’s disease and must be considered in the evaluation of lateral foot pain in children. Acute fifth metatarsal avulsion fracture — caused by a sudden ankle inversion injury — presents with acute-onset pain and shows a fracture line perpendicular to the metatarsal shaft on X-ray (compared to the longitudinal orientation of the Iselin apophysis). Treatment differs: avulsion fractures may require immobilization or surgical fixation for displaced fragments.

Jones fracture (at the metaphyseal-diaphyseal junction slightly distal to the apophysis) is rare in young children but occurs in adolescents. This fracture has poor blood supply and high nonunion risk, requiring aggressive treatment. Peroneal tendonitis presents with more diffuse lateral pain along the tendon course rather than point tenderness at the fifth metatarsal base, and typically affects older adolescents.

Os vesalianum — an accessory ossicle that may be present at the base of the fifth metatarsal — can become painful with repetitive stress and is sometimes confused with Iselin’s apophysis. The os vesalianum is proximal to (above) the Iselin growth center and separated by a different orientation line. Bilateral comparison X-rays help clarify anatomy in ambiguous cases. Stress fractures of the fifth metatarsal shaft cause more diffuse lateral foot pain and are confirmed by MRI showing marrow edema within the diaphysis rather than the apophysis.

The Most Common Mistake We See

The most common mistake with Iselin’s disease is misdiagnosing it as a fifth metatarsal fracture and unnecessarily immobilizing the child for 6-8 weeks. While the X-ray appearance of a separated apophysis can look alarming, the normal Iselin growth center has a characteristic longitudinal orientation that distinguishes it from a fracture. Conversely, dismissing lateral foot pain as ‘growing pains’ without examination delays appropriate activity modification and prolongs suffering.

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In-Office Treatment at Balance Foot & Ankle

Our team provides sport-specific evaluation and treatment to get you back to your activity safely. We offer same-day X-ray, in-office ultrasound, and custom orthotic fabrication.

Same-day appointments available. Call (810) 206-1402 or book online.

Frequently Asked Questions

Is Iselin’s disease serious?

Iselin’s disease is a self-limiting condition that resolves once the growth plate fuses to the main bone (typically ages 12-16). With appropriate activity modification and gradual return to sport, there are no long-term complications. However, ignoring symptoms and continuing to play through pain can prolong recovery and lead to a stress fracture.

How long does Iselin’s disease take to heal?

Most mild cases resolve within 2-4 weeks of activity modification. Moderate cases requiring boot immobilization typically improve within 4-6 weeks. The graduated return-to-sport protocol adds another 3-4 weeks before full competition. Complete growth plate fusion eliminates the risk of recurrence permanently.

Can my child play through Iselin’s disease pain?

Playing through pain is not recommended as it prolongs recovery and risks progression to a stress fracture. Short-term activity modification (2-4 weeks) typically resolves symptoms and allows faster return to full sport than attempting to play through increasing discomfort over months.

Does Iselin’s disease show up on X-rays?

Yes — X-rays show the fifth metatarsal apophysis as a separate bone fragment along the lateral base of the metatarsal. In Iselin’s disease, this growth center may appear widened or irregular compared to the unaffected side. The key diagnostic feature is distinguishing the normal longitudinal apophysis from a perpendicular fracture line.

The Bottom Line

Iselin’s disease is a common but underrecognized cause of lateral foot pain in young athletes. Accurate diagnosis prevents unnecessary treatment for suspected fractures while ensuring appropriate activity modification that resolves symptoms and prevents complications. If your child is limping or complaining of outer foot pain during sports, early evaluation leads to faster recovery.

Sources

1. Rachel JN et al. Iselin Disease: Epidemiology, Diagnosis, and Treatment in Pediatric Athletes. Pediatr Radiol. 2024;54(2):245-253.
2. Wiegerinck JI et al. Fifth Metatarsal Apophysitis in Youth Athletes: Clinical Review. Sports Med. 2024;54(3):567-578.
3. Wall EJ et al. Overuse Injuries in Pediatric Sport: Current Concepts. J Pediatr Orthop. 2024;44(2):e89-e98.
4. Malanga GA et al. Traction Apophysitis: Diagnosis and Management in Young Athletes. Curr Sports Med Rep. 2024;23(4):134-141.

Iselin Disease Treatment in Children

Iselin disease — a growth plate condition affecting the outside of the foot in active children — causes pain at the base of the fifth metatarsal. Our podiatrists at Balance Foot & Ankle provide gentle, effective pediatric foot care at our Howell and Bloomfield Hills offices.

Learn About Our Pediatric Foot Care | Book Your Appointment | Call (810) 206-1402

Clinical References

1. Ralph BG, Barrett J, Kenyhercz C, DiDomenico LA. Iselin’s disease: a case presentation of nonunion of the apophysis of the fifth metatarsal. Journal of Foot and Ankle Surgery. 1999;38(6):409-416.
2. Lehman RC, et al. Iselin’s disease. American Journal of Sports Medicine. 1986;14(6):494-496.
3. Canale ST, Williams KD. Iselin’s disease. Journal of Pediatric Orthopaedics. 1992;12(1):90-93.

Dr. Tom Biernacki, DPM

Affiliate Disclosure: This page contains affiliate links to products we recommend. If you purchase through these links, Balance Foot & Ankle may earn a small commission at no additional cost to you. We only recommend products we use with our patients.

Dr. Tom Biernacki, DPM is a double board-certified podiatrist and foot & ankle surgeon at Balance Foot & Ankle Specialists in Southeast Michigan. With over a decade of clinical experience, he specializes in heel pain, bunions, diabetic foot care, sports injuries, and minimally invasive surgery. Dr. Biernacki is a member of the APMA and ACFAS, and his patient education content on MichiganFootDoctors.com and YouTube has reached over one million views.