P3.R354: “Take Me Out of the Ballgame” A Case of Acromial Apophysiolysis in a High School Softball Pitcher

Introduction: Acromial apophysiolysis is a rare cause of shoulder pain that can develop in athletes with repetitive throwing, caused by failure of acromial fusion due to pulling of the deltoid on the developing acromion. Clinical findings include superior shoulder pain and acromial tenderness. In a recent study, this condition accounted for 2.6% of cases of shoulder pain in patients 15-25 years old.

Case Description: A 16-year-old previously healthy female presented to clinic with a six-month history of gradual onset right shoulder pain, exacerbated by full pitching motion and batting in softball. She denied associated popping or catching and had no history of shoulder injury. She had been involved in physical therapy for six weeks prior to presentation without improvement. Initial exam was positive for mild tenderness to palpation over the acromioclavicular (AC) joint, full range of motion, pain with full forward flexion and positive Neer's and O’Brien’s tests. Her shoulder x-ray was unremarkable. An MRI revealed edema and mild cystic change within the acromion and mild effusion surrounding the biceps tendon. AC joint and biceps tendon sheath injections were performed, after which the pain improved. However, she reported residual pain along the posterior aspect of her right shoulder with external rotation. She continued to work with physical therapy with gradual return to throwing as tolerated. Two years later, she returned to clinic with pain after she resumed softball throwing. Repeat MRI showed persistent edema along the acromial apophysis, indicative of acromial apophysiolysis. (Image 1-2). She decided to forgo her spring season to rest her shoulder and will resume physical therapy in June 2024 with hopes to return to softball in the fall. If pain is not improved, then surgical consultation versus retirement from softball will be considered.

Discussion: Acromial apophysiolysis is an uncommon condition that can be difficult to diagnosis. While x-ray of the shoulder may be normal, MRI can reveal a linear growth plate with irregular margins, diffuse marrow edema, and hyperintense foci next to the growth plate. Treatment includes rest for 2-3 months and physical therapy.

Conclusion: While acromial apophysiolysis is an uncommon condition, patients who remain untreated may develop os acromiale and rotator cuff tears. Therefore, proper identification and treatment of acromial apophysiolysis is important in preventing future injuries in these young athletes.