An apophysis is a secondary ossification center where a muscle-tendon unit inserts in a skeletally immature patient.1,2 Apophysitis is pain, irritation and inflammation of the apophysis caused by repeated traction stress and microtauma to this area.1,2 Apophysitis most commonly presents as an overuse injury in adolescents. As sports become more competitive, with many now being year-round, the number of overuse injuries continues to grow in pediatric patients.1
Iselin disease, one form of apophysitis arising in the foot, was originally described in 1912 as a traction epiphysitis of the base of the fifth metatarsal.3 The apophysis of the fifth metatarsal tuberosity is a secondary center of ossification located within the peroneus brevis tendon insertion site.3,4 Repetitive microtrauma of this apophysis results from trauma to the peroneous brevis during running, jumping or cutting activities, especially while the foot is inverted.3,4 The apophysis of the fifth metatarsal tuberosity appears around the age of 10 for females and the age of 12 for males, and typically goes on to fusion within a year after its appearance.4
Patients presenting with Iselin disease may report a history of an insidious onset of pain to the lateral aspect of the foot. Running, jumping or other sporting activities often exacerbate the pain.1 Patients may relate a history of beginning their seasonal sport or starting gym class. In sports that require cleats, this type of shoe gear will cause increased pain in comparison to other wider athletic sneakers. It is not uncommon for parents with Iselin disease to relate a recent growth spurt.1
Physical examination will reveal tenderness to palpation of the lateral aspect of the base of the fifth metatarsal. There may be mild swelling in this area in comparison with the unaffected foot. One can elicit pain with range of motion testing by having the patient evert the foot against resistance.1
A thorough history and physical examination are important in these patients as a recent traumatic event, such as an ankle sprain or fall from a height with subsequent lateral foot pain, may indicate other pathologies. In these instances, the practitioner should maintain a high suspicion for an avulsion fracture, Jones fracture or other injury.4
Radiographic examination is an important tool when determining if the patient is suffering from Iselin disease or an avulsion fracture off the fifth metatarsal base.4 One can best visualize apophysis of the base of the fifth metatarsal with a medial oblique projection of the foot.3 Apophysis is visible as a small fleck of bone with longitudinal orientation to the long axis of the metatarsal. In an asymptomatic patient, consider this finding a normal variant. The orientation of the bone is important when ruling out an avulsion fracture. Avulsion fractures will also appear as a small fleck of bone but will be oriented perpendicular or oblique to the long axis of the metatarsal.1,3 If the diagnosis remains unclear, obtain radiographs of the uninjured foot for comparison.1
The foundation of treatment for these injuries is rest.2 Counsel these patients on the importance of rest from sports and all activities that cause pain. Advise patients to use ice therapy and analgesics. One may prescribe physical therapy to strengthen the personal muscles and improve flexibility.1,2 Iselin disease may resolve spontaneously as adolescents approach skeletal maturity and the apophysis fuses.4 In patients experiencing severe pain or when relative rest has failed, attempt immobilization of the affected foot with a cast or controlled ankle motion walker.1,2 Young athletes may return to their sport when they are pain-free and have regained full strength.2
The radiographs shown here demonstrate fifth metatarsal apophysitis in an 11-year-old female. She presented to the office after a two-month duration of pain while running and jumping in gym class. The patient and her mother reported no history of trauma or prior injury. They were concerned the pain would prevent her from beginning softball in several weeks.
The physical examination revealed mild edema over the lateral left foot in comparison to the right. No ecchymosis or erythema were present. She had moderate pain to palpation in the area of the fifth metatarsal tuberosity. Mild pain was present with passive inversion and eversion. The patient also had mild pain with active eversion and eversion against resistance.
I diagnosed Iselin’s disease. The patient wore a controlled ankle motion (CAM) boot with scheduled follow-up in two weeks for reevaluation.
- Sando JP, McCambridge TM. Nontraumatic sports injuries to the lower extremity. Clin Pediatr Emer Med. 2013; 14(4):327-39.
- DiFiori JP, Brenner JS, Jayanthi N. Overuse injuries of the extremities in pediatric and adolescent sports. In Caine D, Purcell L (eds.): Injury in Pediatric and Adolescent Sports. Springer International Publishing, Switzerland, 2016, pp. 93-105.
- Fahim R, Thomas Z, DiDomenico LA. Pediatric forefoot pathology. Clin Podiatr Med Surg. 2013; 30(4):479-490.
- Kishan TV, Mekala A, Bonala N, Pavani BS. Iselin's disease: Traction apophysitis of the fifth metatarsal base, a rare cause of lateral foot pain. Medical Journal Armed Forces India. 2015, in press.
- Aiyer A, Hennrikus W. Foot pain in the child and adolescent. Pediatr Clin N Am. 2014; 61(6):1185-1205.
- Apel PJ, Howard A. Evaluation and treatment of childhood musculoskeletal injury in the office. Pediatr Clin N Am. 2014; 61(6):1207-1222.
- Ralph BJ, Barrett J, Kenyhercz C, DiDomenico LA. Iselin's disease: a case presentation of nonunion and review of the differential diagnosis. J Foot Ankle Surg. 1999; 38(6):409-416.