Posterior shoulder pain in throwing athletes with a Bennett lesion: factors that influence throwing pain.

A Bennett lesion is a bony spur at the posterior glenoid that is often seen in baseball players and usually asymptomatic. However, it sometimes becomes painful, but the mechanism of throwing pain is still unknown. The purposes of this study were to identify clinical characteristics associated with the Bennett lesion causing shoulder pain (painful Bennett lesion) and to try to predict which type of Bennett lesion might become painful. Several clinical factors in 51 consecutive baseball players who underwent arthroscopic surgery were investigated. Of these baseball players, 24 had a bony spur: 13 were diagnosed as having a painful Bennett lesion and 11 were diagnosed as having an asymptomatic Bennett lesion, according to our previously reported criteria. The other 27 players did not have a bony spur. Posterior joint laxity, no deficit of internal rotation, and an avulsed fragment on computed tomography scan were determined to be the characteristic clinical features in the shoulders with a painful Bennett lesion.