Background:
The prevalence of medial elbow instability is high in athletes who
throw, such as baseball players. The aim of this study was to assess
the medial aspect of the elbow with ultrasonography to detect changes
in baseball players.
Methods:
Ultrasonography of the medial aspect of the elbow was performed,
while gravity stress was applied with the elbow in 90° of flexion,
on thirty college baseball players (twelve pitchers and eighteen
fielders) to assess medial joint laxity and deformity of the ulnar
collateral ligament. The dominant (throwing) extremity was compared
with the contralateral extremity. Clinical data were correlated
with ultrasonographic findings.
Results:
The medial joint space was significantly wider on the throwing
side than it was on the contralateral side (2.7 mm and 1.6 mm, respectively;
p < 0.01), and the proximal part of the ulna was shifted significantly
laterally on the throwing side (p < 0.01). Angular deformity
of the ulnar collateral ligament was found in five subjects, and
it was significantly associated with lateral shift of the proximal
part of the ulna (p < 0.01). Medial elbow pain was associated
with widening of the medial joint space (p < 0.05) and with
the presence of angulation of the ulnar collateral ligament (p < 0.01).
Conclusions:
Medial elbow laxity and elbow valgus on the throwing side of baseball
players were increased compared with those in nonplayers. Angular
deformity of the ulnar collateral ligament suggests that the ligament
bends over the distal-medial edge of the trochlea. Ultrasonography
can provide useful information about the condition of the ulnar
collateral ligament and about medial elbow laxity in athletes who
throw.