Case Report

Radial Shaft Stress Fracture in a Major League Pitcher

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Upper extremity injuries are associated with significant morbidity in throwing athletes, and prevention and diagnosis of overuse injuries in these athletes are increasingly being emphasized. Although stress fractures are common overuse injuries, stress fractures of the upper extremity are relatively rare. To our knowledge, a stress fracture of the radial shaft has not been reported in a throwing athlete. In this article, we describe the case of a Major League Baseball pitcher who presented with a stress fracture of the lateral cortex of the radius, likely caused by contractile forces of the supinator muscle, arising after his attempt to develop a new pitch.



Take-Home Points

  • Stress fractures should always be considered when dealing with overuse injuries.
  • Radial shaft stress fractures in overhead throwing athletes are rare.
  • Stress fractures can occur anywhere increased muscular forces exceed the bone’s ability to remodel.
  • Proper imaging is necessary to make the diagnosis of a stress fracture.
  • Nonoperative management of radial shaft stress fractures is an effective treatment.

In athletes, the incidence of stress fractures has been reported to be 1.4% to 4.4%. 1 Stress fractures of the upper extremity are less common and not as well described as lower extremity stress fractures. Although data is lacking, stress fractures involving the upper extremity appear to account for <6% of all stress fractures. 2 Stress fractures of the upper extremity, though rare, are being recognized more often in overhead athletes. 3-6 In baseball pitchers, stress fractures most commonly occur in the olecranon but have also been found in the ribs, clavicle, humerus, and ulnar shaft. 2,4,7-10 Stress fractures of the radius are a rare cause of forearm pain in athletes, and there are only a few case reports involving overhead athletes. 4,11-15 To our knowledge, a stress fracture of the radial shaft has not been reported in a throwing athlete. Currently, there are no reports on stress fractures of the proximal radial shaft. 16-18

In this article, we report the case of a radial shaft stress fracture that was causing forearm pain in a Major League Baseball (MLB) pitcher. We also discuss the etiology, diagnosis, and management of stress fractures of the upper extremity of overhead throwing athletes. The patient provided written informed consent for print and electronic publication of this case report.

Case Report

A 28-year-old right-hand-dominant MLB pitcher presented to the clinic with a 4-week history of right dorsal forearm pain that was refractory to a period of rest and physical therapy modalities. The pain radiated to the wrist and along the dorsal forearm. The pain started after the man attempted to develop a new pitch that required a significant amount of supination. The pain prevented him from pitching competitively. Indomethacin, diclofenac sodium topical gel, and methylprednisolone (Medrol Dosepak) reduced his symptoms only slightly.

Physical examination of the right elbow showed mild range of motion deficits; about 5° of extension and 5° of flexion were lacking. The patient had full pronation and supination. Palpation of the dorsal aspect of the forearm revealed marked tenderness in the area of the proximal radius. There was no tenderness over the posterior olecranon or the ulnar collateral ligament, and a moving valgus stress test was negative. No pain was elicited by resisted extension of the wrist or fingers. Motor innervation from the posterior interosseous nerve, anterior interosseous nerve, and ulnar nerve was intact with 5/5 strength, and there were no sensory deficits in the distribution of the radial, median, or ulnar nerves.

Figure 1.
Initial elbow radiographs and elbow magnetic resonance imaging (MRI) were negative. Repeat radiographs taken about 4 weeks after symptom onset showed a very subtle cortical lesion on the lateral and volar cortex of the radius ( Figures 1A, 1B ). A new MRI, ordered to evaluate the entire forearm, confirmed the presence of the cortical lesion and showed significant edema, periostitis, and myositis within the supinator muscle ( Figures 2A, 2B ).
Figure 2.
Computed tomography (CT) showed a linear lucent lesion of the proximal radial shaft, consistent with a stress fracture near the insertion of the supinator muscle ( Figures 3A-3D ). Four weeks later, follow-up CT showed evidence of interval fracture healing with decreased visibility of lucent lines. At 10-week follow-up, CT showed interval bridging callus formation, indicative of a healing stress fracture. The patient, who had no pain with activities of daily living, completed a progressive throwing regimen, advanced to live batting practice, and gradually worked back into competitive play. Total return-to-play time was 12 weeks. The patient remained pain-free and returned to an active MLB roster.
Figure 3.


Stress fractures account for 0.7% to 20% of sports medicine clinic injuries; <10% of all stress fractures involve the rib or upper extremity. 4,6 When the intensity or frequency of physical activity is increased, as with overuse, bone resorption surpasses bone production, locally weakening the bone and making it prone to mechanical failure. Failure is thought to be induced by a combination of contractile muscular forces across damaged bone and increased mechanical loading caused by fatigue of supporting structures. 5,6,19 These forces may have contributed to our baseball pitcher’s development of a stress fracture near

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