Painful Jerk Test: A Predictor of Success in Nonoperative Treatment of Posteroinferior Instability of the Shoulder

Background The jerk test has been used as a diagnostic test of the posteroinferior instability of the shoulder. Pain may or may not be associated with posterior clunking during the jerk test. Purpose To evaluate the presence or absence of pain with the jerk test as a predictor of the success of nonoperative treatment for posteroinferior instability of the shoulder and to identify the pathologic lesion responsible for the pain in the jerk test. Study Design Retrospective review of prospectively collected data. Methods Eighty-one patients (89 shoulders) who had posteroinferior instability with a positive posterior clunk in their shoulders during the jerk test were nonoperatively treated. The patients were divided into 2 groups with respect to the presence of pain in the jerk test: the painless jerk group (54 shoulders) and the painful jerk group (35 shoulders). Response to the nonoperative treatment was evaluated after at least a 6-month rehabilitation program. Patients who did not respond to the rehabilitation underwent arthroscopic examination to identify any pathologic lesions. Results The painful jerk group had a higher failure rate with nonoperative treatment (P< .001). In the painless jerk group, 50 shoulders (93%) responded to the rehabilitation program after a mean of 4 months. Four shoulders (7%) were unresponsive to the rehabilitation. In the painful jerk group, 5 shoulders (16%) were successful with the rehabilitation, whereas the other 30 shoulders (84%) failed. All 34 shoulders that were unresponsive to the rehabilitation had a variable degree of posteroinferior labral lesions. Conclusions The jerk test is a hallmark for predicting the prognosis of nonoperative treatment for posteroinferior instability. Shoulders with symptomatic posteroinferior instability and a painful jerk test have posteroinferior labral lesions.