First Rib Stress Fracture Masquerading as Periscapular Muscle Strain in a 10-Year-Old Softball Player.

INTRODUCTION: First rib stress fractures are uncommon but should be considered in overhead and batting athletes who present with posterior shoulder or periscapular pain. Diagnosis may be delayed because symptoms often resemble periscapular muscle strain, and routine shoulder radiographs may not adequately show the first rib. CASE REPORT: A 10-year-old female softball and basketball player presented with acute right posterior shoulder pain after feeling a "pop" during a batting session. She had recently added upper body conditioning, including ring pull-ups and push-ups, to her training routine. Examination showed medial scapular tenderness, painful but preserved shoulder range of motion, intact strength, no scapular winging, and negative provocative shoulder testing. Shoulder radiographs were interpreted as normal, and she was treated conservatively for a presumed periscapular muscle strain. Her symptoms improved with rest but returned after she resumed softball. On reevaluation, repeat imaging revealed a healing non-displaced right first rib fracture that was visible in retrospect on the initial images. She was restricted from throwing, batting, and overhead activity and was started on calcium and Vitamin D supplementation. At a follow-up, she had returned to full softball participation without recurrent or ongoing pain. DISCUSSION: A first rib fracture can present like a routine periscapular muscle injury. Sudden pain during batting or throwing, a perceived "pop," recurrence with return to sport, and pain with deep inspiration should prompt consideration of rib involvement. Because standard shoulder radiographs may incompletely visualize the first rib, clinicians should deliberately inspect the rib and consider additional imaging when suspicion remains high. CONCLUSION: First rib stress fracture should be considered in batting and overhead athletes with posterior shoulder or periscapular pain, particularly when symptoms recur with return to sport or when pain occurs with deep inspiration. Because standard shoulder radiographs incompletely visualize the first rib, the rib should be deliberately reviewed, as early recognition allows conservative management, complete healing, and successful return to sport.