Objective:To compare the clinical outcomes of arthroscopic external tension band fixation versus open reduction and internal fixation in the treatment of greater tubercle fracture of the humerus.Methods:A retrospective cohort study was conducted on 55 patients with greater tubercle fracture of the humerus admitted to Taizhou Hospital of Zhejiang Province from September 2019 to June 2022, including 24 males and 31 females, aged 26-80 years [(61.7±10.5)years]. Out of them, 35 patients treated with open reduction and internal fixation (open reduction group), and 20 patients were treated with external anchor tension band under arthroscopy (arthroscopy group). The operation time, and the Visual Analogue Scale (VAS) score, American Shoulder and Elbow Surgeons (ASES) score, Constant-Murley score and shoulder active range of motion (anterior flexion, abduction and posterior extension) before operation, at 1 month after operation and at the last follow-up were compared between the two groups. Bone healing was observed in both groups at the last follow-up. Postoperative complications were compared between the two groups.Results:All the patients were followed up for 12-29 months [(16.9±4.0)months]. There was no significant difference in operation time between the two groups ( P>0.05). There were no significant differences in the VAS score, ASES score, Constant-Murley score and shoulder active range of motion between the two groups before operation ( P>0.05). The VAS score of the arthroscopy group was 3(2, 3)points at 1 month after operation, which was significantly lower than that of the open reduction group [4(3, 4) points] ( P<0.01). No significant difference was found in the VAS score at the last follow-up between the two groups ( P>0.05).The ASES scores of the arthroscopy group were (70.6±4.2)points and (90.2±3.7)points at 1 month after operation and at the last follow-up respectively, which were significantly higher than those of the open reduction group [(64.7±6.4)points and (87.5±4.9)points respectively] ( P<0.05 or 0.01). There was no significant difference in the Constant-Murley score between the arthroscopy group [(71.8±4.3)points] and the open reduction group [(70.9±5.3)points] at 1 month after operation ( P>0.05), while the Constant-Murley score of the arthroscopy group was (94.1±3.1)points at the last follow-up, which was significantly higher than that of the open reduction group [(89.2±4.7)points] ( P<0.01). At 1 month after operation and at the last follow-up, ranges of motion of the anterior flexion, abduction and posterior extension were (52.7±12.3)° and (140.0±16.9)°, (57.4±8.6)° and (125.0±14.3)°, and 16(15, 19)° and 25(20, 30)° in the arthroscopy group respectively, which were significantly higher than those in the open reduction group [(42.2±5.2)° and (110.9±14.0)°, (52.8±6.0)° and (103.7±11.7)°, and 10(10, 20)° and 16(15, 25)° respectively] ( P<0.05 or 0.01). At the last follow-up, it was found that bony union was achieved in both groups. There were no obvious complications such as incision infection or joint stiffnessin both groups. In the open reduction group, 2 patients had internal fixation failure within 1-3 months after operation but was treated with revision operation; 6 patients developed shoulder stiffness at 3-6 months after operation but had outpatient rehabilitation. The incidence rate of postoperative complications in the arthroscopy group [0%(0/20)] was significantly lower than that in the open reduction group [23%(8/35)] ( P<0.05). Conclusion:Compared with open reduction and internal fixation with plates and screws, arthroscopic external anchor tension band fixation in the treatment of greater tuberosity fracture of the humerus has the advantages of earlier pain relief, better shoulder functional improvement, better recovery of shoulder mobility, and fewer complications.