RESUMEN
BACKGROUND:Humeral fractures can be treated by using rotary self-locking intramedulary nail. The previous spin in self-locking intramedulary nail has some limitations in application, so it should be improved in its design so as to obtain better biomechanical effect. OBJECTIVE:To improve the design of the rotary self-locking intramedulary nail of the humerus, and to analyze its biomechanical characteristics and application effect, and to provide reference for the clinical treatment of humeral fractures. METHODS: (1) The design of the rotary self-locking intramedulary nail was improved and tested by mechanics test. (2) A total of 63 cases of humeral fractures were randomly divided into two groups: control group (31 cases) and experimental group (32 cases). Patients in the control group received conventional rotary self-locking intramedulary nail, and patients in the experimental group received improved nail. RESULTS AND CONCLUSION:Results of mechanical test concerning anti-axial compression, tensile, torsion and bending were obviously better after improvement than before improvement. No significant difference in range of motion was detected between the two groups (P > 0.05). Compared with that before treatment, the range of motion was significantly increased after treatment in both groups (P < 0.01 orP < 0.05). The range of motion was significantly higher in the experimental group than in the control group (P < 0.05). Simultaneously, the excelent and good rate was significantly higher in the experimental group than in the control group (P < 0.05). Thesedata suggest that the improved rotary self-locking intramedulary nail has better mechanical characteristics and can obtain better clinical effect.