Johannes B. Roedl MD, PhD, Presenter: Nothing to Disclose

William B. Morrison MD, Abstract Co-Author: Consultant, General Electric Company Consultant, AprioMed AB Patent agreement, AprioMed AB Consultant, Zimmer Holdings, Inc

Adam C. Zoga MD, Abstract Co-Author: Nothing to Disclose

To investigate whether edema at the acromial apophysis (ossification center) in young patients ( < 25 years) is associated with a superior shoulder pain syndrome and acromial non-fusion.

Institutional review board approval was obtained, the requirement for informed consent was waived. A retrospective report review of 2372 consecutive patients, between 15 and 25 years of age who underwent shoulder MRIs for shoulder pain was performed. Individuals with edema at the acromial apophysis and no other pathology on MRI were included in the study group. Association of acromial edema with incomplete fusion, baseball pitching (based on a pre-MRI pitching questionnaire) and clinical findings were determined in the study group and in an age and sex matched control group by two readers.

Edema at the acromial apophysis was found in 2.6% (61/2372) of patients. Edema was associated with incomplete fusion of the acromial apophysis (Chi-square, p < 0.001) and superior shoulder tenderness (p < 0.001). The entity was named acromial apophysiolysis accounting for the combination of non-fusion (lysis) and painful edema at the apophysis. In a multivariate regression analysis, a pitch count of more than 100 pitches per week was a risk factor for acromial apophysiolysis (OR=6.5, p=0.017). Six out of the 61 patients with acromial apophysiolysis had a normal MRI of the contralateral (non-throwing shoulder) within 2 weeks. Follow-up imaging with shoulder MRI was available in 29 of 61 patients in the study group and in 22 of 61 patients in the control group. Follow-up imaging showed that acromial apophysiolysis was significantly associated with the development of an os acromiale (OR=138, p < 0.001) and rotator cuff tears (OR=5.4, p=0.015) later in life, after age 25.

Acromial apophysiolysis is characterized by incomplete fusion and edema at the acromial apophysis. It is a cause of shoulder pain in young patients ( < 25 years) and pitching is a risk factor. It predisposes to the development of an os acromiale and rotator cuff tears after age 25.

Young pitchers should not throw more than 100 pitches per week to prevent acromial apophysiolysis, a cause of shoulder pain and risk factor for os acromiale and rotator cuff tears later in life.

Roedl, J, Morrison, W, Zoga, A, Acromial Apophysiolysis of the Skeletally Immature Shoulder: Prevalence, Risk Factors and Association with os Acromiale and Rotator Cuff Tears.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045731.html