October 24, 2014
1 min read

Injury more likely in pitchers who throw more than 100 pitches weekly

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Young baseball pitchers who threw more than 100 pitches weekly were found to be at a heightened risk for acromial apophysiolysis, according to recently published data.

“We believe that as a result of overuse, edema develops and the acromion bone does not fuse normally,” study author Johannes B. Roedl, MD, said in a press release.

Johannes B. Roedl

Roedl and colleagues reviewed 2,372 patients between ages 15 and 25 who underwent an MRI due to shoulder pain between 1998 and 2012. Patients were matched by age and sex to healthy controls for comparison using both univariate and multivariate binary logistic regression analyses. Acromial edema associated with incomplete fusion, pitching history, clinical data, and later-in-life os acromiale and/or rotator cuff tears was evaluated.

“We kept seeing this injury over and over again in young athletes who come to the hospital at the end of the baseball season with shoulder pain and edema at the acromion on MRI, but no other imaging findings,” Roedl said.

Edema at the acromial apophyses was found in 61 patients and was associated with incomplete fusion of the acromial apophyses and superior shoulder tenderness, according to the researchers.

An athlete’s pitch count exceeding 100 weekly pitches was significantly linked to greater odds ratio of acromial apophysiolysis. This weekly pitch count was also associated with heightened odds ratios of os acromiale and rotator cuff tears, as well as greater tear severity via imaging taken after age 25.

Imaging also revealed that after having taken a 3-month absence from pitching, 25 patients in the injury cohort had incomplete fusion of the acromion vs. one patient in the control cohort.

Of the 21 patients who continued pitching after the 3-month absence, all showed incomplete acromion bone fusion. Overall, 40% of pitchers in the injury cohort threw more than 100 pitches weekly, compared with 8% in the control cohort.

“The occurrence of acromial apophysiolysis before the age of 25 was a significant risk factor for bone fusion failure at the acromion and rotator cuff tears after age 25,” Roedl said.

Disclosure: Roedl has no relevant financial disclosures.