Working Diagnosis:
Right grade 4b ulnar diaphysis stress fracture

Treatment:
After initial evaluation, the patient was placed into a wrist brace, instructed on complete rest of the right arm (no throwing, batting, lifting, or carrying) and advised to ice the area and continue Aleve as needed for pain management. After re-evaluation 1 month later, the patient was instructed to continue to wear a splint for one additional week. She was then weaned from the wrist brace during the following week for a total of six weeks of immobilization. After the six weeks, physical therapy was initiated with a return to pitching program consisting of gradual advancement of throwing as tolerated. Two months after her last evaluation, the patient participated in her first game and denied any recurrent symptoms. To date, she denied any reoccurrence of her symptoms.

Outcome:
The final 2-view forearm X-rays obtained on the last clinic visit 2.5 months after the initial evaluation demonstrated progressive, near complete healing of the ulnar midshaft stress fracture. Case Photo #5 Case Photo #6
After the six week period, the patient progressed from total rest to overhand throwing only, then to eventually returning to bullpen sessions where she threw only fastballs and changeups. She gradually advanced to throwing with strict pitch count limits and pitching only once per week. She was then eventually able to perform her regular routine. Two months after her last evaluation, she participated in her first softball game. On that day she played in two games throwing forty pitches in the morning game and then moving onto play a full evening game without pain or symptoms. She was also able to complete her high school and summer club seasons without any symptoms.

Author's Comments:
Stress fractures are a partial or complete fracture through the bone due to the repeated application of stress that is lower than that required to fracture the bone in a single loading situation. (1) Lower extremity stress fractures represent the vast majority of stress fractures in the literature. When upper extremity stress fractures are described, and more specifically pertaining to ulnar stress fractures in softball players, a more common location is the ulnar olecranon. (1) This case is unique in that the stress fracture occurred in the diaphysis and only a handful of case reports discuss such injuries. Ulnar diaphysis stress fractures have also been recognized in a spinner bowler, tennis player, baton twirler, recreational golfer and due to excessive push-ups. (2-8). In a case report of an ulnar stress fracture in a softball pitcher by Fujioka et al., they believe that the mechanism of ulnar diaphysis stress fractures are due to windmill pitching. In windmill pitching, the pitcher rotates and swings their arm around the shoulder and powerfully hits their forearm to their thigh (AKA "brushing") with simultaneous pronation of the forearm and flexion of the wrist. (2) They postulate that, "although the elbow is extended, the wrist and fingers are flexed by the forearm flexor muscles powerfully and the forearm is stressed by torsion and a direct blow". (2) In line with all articles reviewed, our patient obtained a full recovery with conservative treatment consisting of complete rest, physical therapy and a gradual return to pitching.

Editor's Comments:
There are a number of proposed mechanisms that may lead to ulnar shaft stress fractures. Pronation is postulated as a cause for stress fracture at the middle third of the ulna, owing to it relatively small cross-sectional area, its triangular shape (versus circular at the proximal and distal third), and its thin cortex in this region of the bone. Another possible mechanism for an ulnar stress fracture includes a combined axial and torsional force, as that in a breakdancer performing a spin with his or her entire weight on one hand. A third potential mechanism is the repeated overuse or stress of the flexor digitorum muscle mass, as in weight lifting with the elbow flexed and the wrist in pronation or supination3; or with repeated strong grasping with flexion at the elbow, as in the case of an elite bobsled brakeperson, or with perpendicular force applied to the ulna with the hand in full grip, as in the case of an elite polo player.

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