PM1081: Trust Your H&P: Acute Thigh Pain in an 11-year-old Soccer Player with Normal X-rays

Introduction: An 11-year-old female presented to the Emergency Department (ED) with right thigh pain after a pivoting injury during a soccer game the previous day. She was diagnosed with an occult avulsion fracture of the ischial tuberosity. As the ischial tuberosity ossification center does not appear until age 13-15 and does not fuse until age 16-25, the area is still cartilaginous and thus initial x-rays may appear normal.

Case Description: During a soccer game, the patient pivoted suddenly and felt a popping sensation and pain in her right thigh. She was unable to bear weight thereafter. The following day she presented to the ED. On physical exam she was seated with right hip and knee flexed. There was no swelling, erythema, or tenderness to palpation of the right hip, femur, knee, or tibia/fibula. She could not fully extend the knee and had limited range of motion of the hip secondary to pain felt in her hamstrings. Plain films of the pelvis and right femur were normal. She was given crutches and made non-weightbearing. She was then seen in Pediatric Sports Medicine clinic where she had tenderness of the right hamstrings and pain with right hip flexion, adduction, and internal rotation. Plain films of the hips and pelvis revealed mild irregularity of the right ischial tuberosity. Given the acuity and severity of her symptoms, the injury was treated as an occult avulsion fracture of the ischial tuberosity. She completed two weeks of full non-weightbearing and two weeks of partial weightbearing, followed by physical therapy. Three months post injury, she returned to soccer practice.

Discussion: Pelvic avulsion fractures usually occur in the adolescent athlete, in sports that require forceful muscle contraction. The hamstrings form a common tendon proximally that attaches to the ischial tuberosity. Prior to appearance of the ischial tuberosity apophysis around age 13-15 and fusion to the pelvis around age 16-25, this area is largely cartilaginous and an avulsion thus may not be visible on plain films. Pelvic avulsion fractures are usually managed conservatively with a period of rest prior to beginning physical therapy. Return to sport usually takes several months.

Conclusion: The differential diagnosis for a skeletally immature athlete presenting with acute thigh pain and inability to bear weight after a pivoting injury is broad. One must have a high level of suspicion for an occult injury of the pelvis even when initial radiographs are normal, because the ischial tuberosity ossification center does not appear until age 13-15 and does not fuse until age 16-25. Therefore, initial x-rays may be normal and one must trust the history and physical exam to accurately diagnose and treat the patient. Failure to identify this injury can lead to complications such as pain and decreased athletic performance.