ObjectiveTo investigate the clinical significance of Q-angle measuring under different conditions in female recurrent patellar dislocation female patients. MethodsBetween August 2012 and March 2013, 10 female patients (11 knees) with recurrent patellar dislocation were collected as trial group; 20 female patients (20 knees) with simple meniscus injury were collected as control group at the same time. Q-angle was measured in extension, 30° flexion, 30° flexion with manual correction, and surgical correction in the trial group, and only in extension and 30° flexion in the control group. Then the difference value of Q-angle between extension and 30° flexion (Q-angle in extension subtracts Q-angle in 30 flexion) were calculated. Independent sample t-test was used to analyze Q-angle degrees in extension, 30° flexion, and the changed degrees of 2 groups. The Q-angle between manual correction and surgical correction of the trial group was analyzed by paired t-test. ResultsThe Q-angle in extension, Q-angle in 30° flexion, and difference value of Q-angle between extension and 30° flexion were (17.2±3.6), (14.3±3.0), and (2.9±1.9)° in the trial group and were (15.2±3.4), (14.4±3.5), and (0.8±1.7)° in the control group. No significant difference was found in Q-angle of extension or Q-angle of 30° flexion between 2 groups (P>0.05), but the difference value of Q-angle between extension and 30° flexion in the trial group was significantly larger than that in the control group (t=3.253, P=0.003). The Q-angle in 30° flexion with manual correction and surgical correction in the trial group was (19.8±3.4)° and (18.9±3.8)° respectively, showing no significant difference (t=2.193, P=0.053). ConclusionWhen a female patient's Q-angle in 30° flexion knee changes obviously compared with Q-angle in extension position, recurrent patellar dislocation should be considered. For female patients with recurrent patellar dislocation, the preoperative Q-angle in 30° flexion with manual correction should be measured, which can help increasing the accuracy of evaluation whether rearrangement should be performed.