P3.R357: Ischiopubic stress injury in a 9 year old baseball player: A Case Report

Introduction: The ischiopubic synchondrosis (IPS) is a temporary hyaline joint between the inferior ischial and pubic rami, formed between 4 and 12 years. It occurs until skeletal maturity when it undergoes bony union, typically demonstrating bilateral enlargement. Fusion is noted between 4 and 9 years in females versus 7 and 13 in males. Bilateral fusion of the IPS is seen in 80% of children by 12 years. [5] However, unilateral IPS enlargement can be seen closer to puberty and found to correlate with foot dominance due to increased force on the non-dominant foot with physical activity [3]. The appearance of IPS enlargement, whether unilateral or bilateral is nonspecific on xray. Radiographic findings may be noted in asymptomatic individuals. presence nor absence of IPS should be considered diagnostic and further evaluation is warranted.

Case Description: A 9-year-old male baseball player with 9 months of left sided groin pain with activity including weight training and hitting with a weighted bat. Pain was noted with running/stretching and caused a limp. Exam was notable for tenderness at the proximal adductor tendon and insertion with decreased internal rotation and strength of the hip, limited by pain.

X-ray of the hip and pelvis were unremarkable. MRI of the left hip revealed a stress reaction at the IPS with reactive edema to the surrounding soft tissues and musculature. Clinical presentation, exam and imaging were consistent with a stress fracture of the IPS. He was managed conservatively with activity modification, physical therapy and a home exercise program. After 6 weeks he was pain free at rest, exercises, and exam.

Discussion: Stress fracture/reaction of the IPS are a result of increased mechanical stress and micro-instability due to asymmetric loading of adductors, flexors and external rotators used with high impact and torsional activities. [6] Patients may present with atraumatic hip/groin, gluteal or adductor pain and limping. Differential should include avulsion fracture of the pubis, muscle strain, stress fracture, hernia, SCFE and van Neck-Odelberg disease. Diagnosis can be made with history, exam and imaging.

Enlargement of the IPS has been documented since 1924, when Van Neck noted IPS enlargement, coining this as “osteocondritis ischiopubica”. Further research provided insight, recongnizing it to be a benign and spontaneous process. Terminology evolved to “osteochondrosis” or “osteochondropathia” and eventually “ischiopubic synchondrosis” [4, 7]. It is now recognized that the asymmetric enlargement of the IPS is a physiologic response to asymmetric mechanical stress of the adductors, iliopsoas and gemellus at the hemipelvis which can delay union of the cartilage and ossification center.[3]

Conclusion: Asymptomatic IPS enlargement should not be confused for stress reaction. Although asymmetric IPS enlargement can be a normal phenomenon, physicians must ensure complete work up for underlying disease pathologies and may include MRI.