## 4 Discussion
Comparatively, in our study, we found that patients with FS who received posterior glide and inferior glide joint mobilization (30 min each treatment course, three times a week, for eight weeks) applied by the joint mobilization apparatus plus the regular therapy demonstrated 36% and 81% improvement in shoulder flexion and internal rotation. Meanwhile, the shoulder flexion and internal rotation of the patients who received the joint mobilization apparatus plus regular therapy was 11%, i.e., 41% higher than that of patients who received regular therapy only in this study. In addition, we also observed that patients with FS in the experimental group (joint mobilization apparatus plus regular therapy) had more improvement in shoulder externalrotation than patients with FS in the control group (regular therapy alone). Even though according to the principle of joint mobilization and the concave-convex rule [24; 25], the anterior glide that can improve shoulder external rotation, which we did not apply in the joint mobilization apparatus treatment, however, [PERSON] et al. also reported posterior glide manual mobilization (15 min each treatment session, 2-3 times per week, 6 sessions total) for improving external rotation by 31.3 degrees are more effective than anterior glide for improving external rotation by three degrees in patients with FS [34], which is contrary to the findings based on the concave-convex rule. In our study, shoulder external rotation in the patients who received the posterior glide and inferior glide joint mobilization (30 min each treatment course, three times a week) applied by the joint mobilization apparatus plus regular therapy for eight weeks showed 88% improvement from the baseline as well as was 24% better than that in patients who received regular therapy only. The posterior glide and inferior glide of the joint mobilization apparatus just like the posterior glide of manual mobilization can also help patients with FS improve shoulder external rotation. Relative to shoulder pain in patients with FS, manual joint mobilization can produce mechanical stimulation and neurophysiological effects on the human body through repeated oscillation stimulation, so that it has an inhibitory effect on the sensation of pain [35; 36]. Previous studies have shown that manual shoulder joint mobilization had efficacy and effectiveness in reducing shoulder pain of patients with FS [29; 30; 31]. [PERSON] et al. confirmed that the manual shoulder joint mobilization technique which combined with the exercise achieved efficacy to improve shoulder pain in patients with FS. This study showed that the VAS pain score in patients with FS who received two directions (inferior, anterior) manual shoulder joint mobilization (2-3 glides per second, every direction 30 s, repeated five sets, three times per week for four continuous week) combined with exercise was 27% lower than that of patients who received exercise only after treatment [29]. [PERSON] et al. found that the Kaltenborn and Maitland posterior glide of the manual shoulder mobilization techniques (one glide per second, 10 min each treatment course, three times per week for four weeks) were able to effectively decrease the VAS pain scores about 52% and 48% in patients with FS after the treatments [31].Comparatively, we found that VAS score of shoulder pain in the patients with FS who received posterior glide and inferior glide joint mobilization (five glides per second, 30 min each treatment course, three times a week for eight weeks) applied by joint mobilization apparatus plus regular therapy was 62% lower than baseline as well as was 34% lower than that in patients who received regular therapy only in this study. The shoulder joint mobilization performed by the joint mobilization apparatus can help patients with FS to relieve pain. The apparatus treatment force output and the frequency were set at 80 N and 5 Hz during treatment in this study based on the actual situation of the device operation and the patient's sensation and safety.