MRI Web Clinic — May 2005

Little League Elbow
Mark H. Awh, M.D.

Clinical History: A 15 year-old baseball pitcher presents with persistent medial elbow pain. Fat suppressed proton density-weighted (1a) coronal and (1b) axial images are provided. What are the findings? What is your diagnosis?

1a
1b
Figure 1:

Fat suppressed proton density-weighted (1a) coronal and (1b) axial images

Findings

2a
2b
Figure 2:

Abnormal marrow edema compatible with a stress reaction (arrows) is identified within and deep to the medial epicondylar apophysis on both the proton density weighted (2a) coronal and (2b) axial images of the elbow. On the coronal image, the anterior band of the ulnar collateral ligament appears mildly edematous and demonstrates subtle laxity at its proximal aspect (arrowhead).

Diagnosis

Little League Elbow

Discussion

In 1960, Brogdon and Crow1 described two cases of separation and fragmentation of the medial epicondylar apophysis in the elbows of little league pitchers, and coined the term “little leaguer’s elbow.” Both pitchers presented with pain and tenderness over the medial epicondyle in their pitching arms. Since that early description, the designation of little league elbow has expanded to include a host of abnormalities that affect the throwing elbow in adolescent pitchers.

In the throwing athlete, the acceleration phase of the overhead throw causes extreme valgus stress upon the elbow.2 The “whipping” action of the throw causes lateral compression and resultant tension on medial supporting structures, particularly the ulnar collateral ligament. The ulnar collateral ligament is composed of three bands, the anterior band, the transverse band, and the posterior band (3a). The anterior band is by far the most important, providing the major restraint to valgus stress at the elbow. The anterior band arises from the anteroinferior aspect of the medial epicondyle and inserts upon the sublime tubercle of the ulna. In adults, the repetitive valgus forces of throwing often result in chronic degeneration, microtears, or rupture of the ulnar collateral ligament. In adolescents, the immature apophysis of the medial epicondyle is often the weaker link, and injuries that affect this ossification center may thus predominate in the young thrower (4a).

3
Figure 3:

(3a) The three bands of the ulnar collateral ligament are depicted in this illustration of the medial side of the elbow. The posterior band (PB) and transverse band (PB) are relatively weak. The anterior band (AB), which inserts near the coronoid process, is the primary restraint to valgus force at the elbow through the functional range of motion.

4
Figure 4:

(4a) In the immature skeleton, traction from the thick anterior band of the ulnar collateral ligament may result in a variety of stress-related injuries at the medial epicondylar apophysis.

This month’s case is actually a relatively mild form of little league elbow, with only an apophyseal stress reaction and mild sprain of the ulnar collateral ligament noted. Additional findings that may be present in little league elbow include overgrowth of the medial epicondylar apophysis, separation and fragmentation of the apophysis, complete tears or avulsions of the ulnar collateral ligament (5a,6a), flexor/pronator muscle strains, and proximal ulna stress fractures. Because of the repetitive valgus forces that occur with this entity, the medial injuries may be seen in conjunction with compression abnormalities of the lateral compartment (7a,8a,9a). In some cases, osteochondritis dissecans of the capitellum may develop(10a,11a).3

5
Figure 5:

(5a) A fat-suppressed T2 weighted coronal image in a 15 year old baseball pitcher reveals an avulsion fracture (arrow) of the medial epicondylar apophysis, at the proximal attachment of the ulnar collateral ligament.

 

6
Figure 6:

The avulsed bony fragment (arrow) is confirmed on (6a), a proton density-weighted sagittal image.

Multiple fat-suppressed T2-weighted coronal images (7a – 9a) reveal combined elbow injuries in a 12 year-old baseball pitcher.

 

7
Figure 7:

On (7a), an anterior image, edema secondary to chronic lateral compression (arrows) is identified within the capitellum and the radial head.

 

8
Figure 8:

(8a) The 2nd coronal image demonstrates a tear of the anterior band of the ulnar collateral ligament at the distal attachment (arrow).

9
Figure 9:

(9a) On a posterior coronal image, edema compatible with a stress reaction is noted throughout the medial epicondylar apophysis (arrow).

 

10
Figure 10:

(10a) A T1-weighted coronal image demonstrates an osteochondral lesion (arrow) compatible with osteochondritis dissecans of the capitellum in a 16 year-old baseball pitcher. Note the sclerosis along the articular surface of the radial head (arrowhead), also likely secondary to repetitive lateral impaction stress.

 

11
Figure 11:

(11a) On the T2-weighted sagittal view, fluid signal intensity is seen along the base of the osteochondral lesion (arrow), suggesting lesion instability.

Patients with little league elbow may complain of medial elbow and proximal forearm pain a few days after pitching. Symptoms abate with rest initially, but with progression, pain becomes more continuous and the player may report difficulty “loosening up” or maintaining throwing accuracy. Parents and coaches must be particularly vigilant, as young athletes often will not report early symptoms unless specifically queried.

Plain radiographs in patients with little league elbow may demonstrate widening of the growth plate or overgrowth of the medial epicondylar apophysis. Osteochondritis dissecans of the capitellum is typically difficult to diagnose with plain films until late in the disease. The advent of MRI has dramatically improved our ability to diagnose the underlying pathologies in little league elbow. Near-identical patient symptoms may be caused by a wide variety of elbow pathologies, and MRI’s ability to specifically identify and characterize the soft tissue and osseous abnormalities that may be present is unparalleled.

The treatment approach in patients with little league elbow is often guided by the MRI findings. Apophyseal stress reactions, ligamentous sprains, muscle strains, and minimally displaced apophyseal avulsions may be treated conservatively, and the response to conservative therapy can be followed with MRI. Conservative treatment includes the immediate cessation of throwing, use of anti-inflammatory medications, application of ice, and stretching programs.4 If apophyseal avulsions are displaced by 3-4mm or greater, surgical reattachment is typically indicated. Full thickness ulnar collateral ligament tears may necessitate reconstruction, often with a palmaris longus graft, the so-call “Tommy John procedure.” In patients with osteochondritis dissecans of the capitellum, the presence of an unstable fragment or loose bodies within the joint are common indications for surgery.

Following treatment of little league elbow, the return to throwing should be approached cautiously. A strength and flexibility exercise regimen should be rigorously adhered to, and pitch counts should be limited to 80 to 100 pitches per week. Prior to high school, torsional pitches such as curveballs and sliders are to be avoided. Any recurrence of symptoms necessitates cessation of throwing and a re-evaluation of the patient.

Conclusion

Little league elbow refers to a multitude of soft-tissue and osseous abnormalities that may affect the adolescent throwing athlete. Though common in today’s society, many of these injuries were virtually unheard of in children prior to the advent of organized baseball. MRI is invaluable in these patients, as it allows differentiation of the many causes of elbow pain in the young thrower. Treatment options and the post-treatment assessment are often guided by the MRI findings in these patients.

References

1 Brogdon BG, Crow NE: Little Leaguer’s elbow. Am J Radiol 83: 671?675, 1960

2 Fleisig GS, Andrews JR, Dillman CJ, Escamilla RF: Kinetics of baseball pitching with implications about injury mechanisms. Am J Sports Med 1995 Mar-Apr; 23(2): 233-9

3 Slocum DB: Classification of elbow injuries from baseball pitching. Tex Med 1968; 64(3): 48-53

4 Andrews JR, Arrigo CA, Chmielewski T, et al: Preventive and Rehabilitative Exercises for the Shoulder & Elbow. Birmingham, AL, American Sports Medicine Institute, 1997

Be the first to read our web clinics

Sign up for our monthly e-mails.