Working Diagnosis:
Non-displaced mid-shaft stress fracture of the left ulna.

Treatment:
The patient was treated with a volar wrist brace, active rest, and counseled to avoid strenuous physical activity involving the affected extremity. She used over-the-counter topical and oral analgesics for pain control. She completed a course of physical therapy and progressed to a throwing program.

Outcome:
After 8 weeks of conservative management, the patient had improvement of her symptoms. Follow-up plain films showed callous formation along the mid-shaft of the ulna Case Photo #7 Case Photo #8 . She was able to subsequently return to playing softball.

Author's Comments:
The presented case was very interesting to me due to the low and rare incidence of an ulnar stress fracture, what it entails in a female athlete, considering not only the biomechanics but also considering gender, hormonal and metabolic factors, and the comparison between softball and baseball regarding biomechanics and the rules of pitching, including limiting the number of pitches.

Editor's Comments:
This case of an ulnar stress fracture in a softball pitcher highlights the need for clinicians to be suspicious for stress injuries in throwing athletes presenting with forearm pain. In a study of the cross-sectional area of the ulna on CT scans in softball pitchers, Tanabe et al. found that the middle third of the ulna had the smallest diameter and thinnest bony cortices, predisposing the midshaft of the ulna to stress injuries (1). Proposed mechanisms leading to stress injuries in softball pitchers include chronic torsional stress and repetitive pronation of the forearm (2). While there is no current standard on pitch counts in softball and the topic is debated, case reports of ulnar stress fractures in softball pitchers raises the need for further research to inform best practices to keep softball pitchers on the field.

References:
1. Tanabe S, Nakahira J, Bando E, Yamaguchi H, Miyamoto H, Yamamoto A. Fatigue fracture of the ulna occurring in pitchers of fast-pitch softball. Am J Sports Med. 1991 May-Jun;19(3):317-21. doi: 10.1177/036354659101900318. PMID: 1867340.
2. Myrick KM, Myrick SA, Ezomo O. Ulnar stress fracture in a softball player. Clin Case Rep. 2020 May 28;8(8):1547-1552. doi: 10.1002/ccr3.2933. PMID: 32884793; PMCID: PMC7455444.

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