Introduction

Little Leaguer’s elbow, a well-known radiologic abnormality, manifests as an avulsion injury of the medial epicondyle of the elbow. To our knowledge, however, there is little in the current radiologic literature describing the less well known entity of Little Leaguer’s shoulder. Little Leaguer’s shoulder manifests as widening of the proximal humeral physis in adolescent athletes between the ages of 13 and 16 years and was first described in the sports medicine literature by Dotter in 1953 [1]. As radiologists, it is important that we be aware of such clinical diagnoses so that we may better serve our clinical associates. This is especially important when a specific radiologic finding is critical to the diagnosis, as is the case with Little Leaguer’s shoulder. We report such a case.

Case report

A 12-year-old male baseball player presented for evaluation of right shoulder pain. The patient stated that he had experienced pain in the lateral proximal humerus for approximately 2 weeks. The pain had been gradually increasing and was worse while pitching. In fact, several days prior to presentation, the patient was only able to pitch half of an inning, restricted by pain in his shoulder. The patient was approximately 2 months into the baseball season at the onset of symptoms and denied experiencing an acute injury. There was no history of numbness, tingling, weakness or neck pain.

Physical examination demonstrated positive tenderness to palpation over the proximal humerus laterally and mild pain with external rotation. The remainder of the physical examination was unremarkable.

Bilateral, internal and external rotated anteroposterior views of the shoulders were obtained and demonstrated physeal widening on the right compared with the left (Figs. 1, 2). Little Leaguer’s shoulder was diagnosed and the patient was instructed to rest his shoulder for 4–6 weeks. No follow-up radiographs were obtained and the patient was able to return to pitching without further intervention.

Fig. 1A, B
figure 1

Radiographs of the right shoulder demonstrate widening of the proximal humeral physis (arrows)

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Fig. 2A, B
figure 2

Radiographs of the left shoulder in the same patient with a normal appearance of the proximal humeral physis for comparison

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Discussion

Fractures involving the proximal humeral physis make up approximately 3% of physeal injuries [2]. During development, the proximal humerus initially contains three separate ossification centers (first year of life, humeral head; age 2–3 years, greater tuberosity; age 5–6 years, lesser tuberosity) which coalesce around the age of 7 years and fuse with the humeral metaphysis some time between the ages of 16 and 20 years [3, 4]. Adolescents are more prone to this type of injury because of the accelerated growth that occurs at this age coupled with the fact that 80% of longitudinal growth of the humerus occurs at the proximal physis [5]. Baseball players tend to be the most commonly affected athletes and the average age reported in one of the largest case series (23 cases) was 14 years old with a range from 13 to 16 years old [6]. Similar cases of proximal humeral physeal widening (Salter-Harris type I fractures) have also been reported in an adolescent gymnast [7] and in an elite junior badminton player [8].

Classically, patients with Little Leaguer’s shoulder present with gradual onset of shoulder pain while throwing and tenderness to palpation over the lateral proximal humerus. Generally, no acute injury is reported and pain may be experienced during any phase of the throwing motion [6]. The diagnosis is suspected from the clinical history and pain with resisted external rotation of the humerus. Correlation with bilateral, internal and external rotation anteroposterior radiographs of the shoulder confirms the diagnosis. All patients with symptoms for more than 3 weeks demonstrate proximal humeral physeal widening (Salter-Harris type I fracture). Reported associated radiographic abnormalities include demineralization, sclerosis of the proximal humeral metaphysis, fragmentation of the lateral aspect of the proximal humeral metaphysis and cystic changes [9, 10, 11]. Radiographs are usually normal if symptoms have been present for less than 10 days. One would speculate that MRI would be more sensitive to the detection of physeal injury during this early phase; however, we are not aware of any reports of this in the radiologic literature.

Little Leaguer’s shoulder is most likely an overuse syndrome related to significant rotational stress applied to the proximal humeral physis that occurs with throwing [6]. During the act of throwing, the shoulder changes from an abducted externally rotated position to an internally rotated adducted position [12]. Pitchers attempting to throw hard, and especially to throw curves, are most at risk. Torg et al. [13] proposed a discrepancy between the incidence of proximal humeral injury in adolescent boys playing recreational baseball and competitive Little League baseball. Torg et al. found no radiographic evidence for injury in the 44 recreational league players they evaluated, and compared their findings with those of Adams’ [9] study of Little Leaguers in which he describes five cases of Little Leaguer’s shoulder in adolescents playing competitive baseball.

Treatment consists of at least 6 weeks of rest followed by physical therapy, with gradual return to a throwing program when symptoms subside. Radiographic remodeling of the widened proximal humeral physis can take several months and a decision on when to return to throwing is based on clinical rather than radiologic grounds. Twenty-one of 23 patients in Carson and Gasser’s series were able to return to asymptomatic baseball activity following appropriate rest [6].

Radiologists should be familiar with the clinical diagnosis of Little Leaguer’s shoulder and should include it in their differential diagnosis of shoulder pain in an adolescent athlete, especially if he or she is involved in a competitive sport which requires a repetitive throwing-type motion. The radiographic findings may be subtle and if proximal humeral physeal widening is suspected on an anteroposterior radiograph then comparison views of the contralateral shoulder should be obtained. By alerting clinicians to the possibility of this diagnosis, the radiologist can expedite the correct treatment of rest, thus allowing young athletes to resume pain-free playing. Additionally, further imaging with MRI or bone scans can be avoided.