A Rare Cause of Foot Pain in an Adolescent Male Multisport Athlete

Abstract

HISTORY: A 13 year old male football, basketball, and baseball athlete presented to sports medicine clinic with a 3 month history of non-traumatic exertional right lateral foot pain. He reported 8/10 pain with strenuous activities, such as running and jumping. He had no pain with walking. He reported aching discomfort in the morning upon waking. He denied numbness, tingling, or abnormal sensation. PHYSICAL EXAMINATION: There was no significant deformity. He was able to walk with a non-antalgic gait. There was tenderness to palpation over the lateral base of the 5th metatarsal. Range of motion of the foot and ankle was normal. There was normal strength upon manual muscle testing, but resisted ankle eversion reproduced pain. He was neurovascularly intact. DIFFERENTIAL DIAGNOSIS: 1. Metaphyseal-Diaphyseal (Jones) Fracture 2. Fifth Metatarsal Stress Fracture 3. Traction Apophysitis (Iselin’s Disease) 4. Insertional Peroneal Tendinopathy 5. Avulsion Fracture TESTS AND RESULTS: - Right foot radiograph: Well-corticated bone fragment proximal and perpendicularly-oriented to the base of the 5th metatarsal, representing an accessory ossicle (os vesalianum) versus ununited fracture. No evidence of acute fracture and normal-appearing apophysis. - Right foot MRI: Osseous body at base of the 5th metatarsal with irregular margins, hyperintense T2 fibrous union, and internal edema of the ossicle and adjacent proximal metatarsal, favored to represent a symptomatic os vesalianum. No increased apophyseal distraction. FINAL WORKING DIAGNOSIS: Symptomatic Accessory Os Vesalianum TREATMENT AND OUTCOMES: 1. Immobilize in a walker boot for 6-8 weeks. 2. Physical therapy after immobilization, with emphasis on peroneal muscle strengthening and range of motion. 3. If complete resolution of symptoms, may gradually return to sport as tolerated. If symptoms persist, consider surgical excision.