| Objective To study the changes of bone mineral density (BMD) and its significance in patients after lower limb fracture operation. Methods One hundred and two lower limb fracture patients at the Department of Orthopedics, the First Affiliated Hospital of Dalian Medical University from October 2014 to October 2017, were admitted to the study, including 55 males and 47 females. They were from 20 to 60 years old, with an average of 43.5±12.5 years. Among those, 84 cases were unilateral fracture, 18 cases were bilateral fractures. There were 22 cases of open injury and 80 cases of close injury. The operations were performed in 2 hours to 7 days after the fracture. They were followed up at the 1, 2, 3, 6, and 12 months after the operation. BMD of the both calcaneus was measured using ultrasonic bone densitometry. BMD of the both calcaneus was measured in 39 healthy outpatients at the same period, and the average was used as the control. The change of BMD after fractures was observed, and the influencing factors were analyzed. Results (1) BMD of the patients with unilateral lower limb fracture decreased rapidly from 1 to 3 months. The decrease was slow in the period from 3 to 6 months, and the lowest point was at the end of 6 months after the operation. BMD increased slowly from 6 to 12 months, but it was still lower at 12 months than at the level of preinjury. Comparing the BQI value among the healthy limb, the affected limb, and the controls in 1, 2, 3, 6, and 12 months after the operation group, the difference was statistically significant, and the difference between any two groups was statistically significant (P<0.05). (2) in patients with unilateral lower limb fractures, the BQI value ins male was higher than that in females, but the difference was not statistically significant (P>0.05). (3) There was not significant difference of BMD of the healthy limb and the affected limb between the different anatomic sites of single side fracture (P>0.05). BMD of the unilateral fracture was higher than that of bilateral fracture, and the difference was statistically significant (P<0.05) in 2, 3, 6, and 12 months after the operation. (4) BMD in Gustilo-Anderson type Ⅲ of the open injury was significantly different compared with that of the close injury in 2, 3, 6, and 12 months after operation (P<0.05). BMD in Gustilo-Anderson type I and II of open injury was not statistically different compared to the closed injury (P>0.05). Conclusion In the healing process of lower limb fracture, BMD of the lower limb decreases rapidly in 1-3 months, slowly in 3-6 months, and increases slowly in 6-12months. It may be related to the decrease of limb activity, the decrease of mechanical stress, and the degree of soft tissue injury around the fracture. Anatomical site of fracture and gender may have no significant influence on the changes of BMD. It is necessary to have early exercise and combination drug therapy in order to prevent the decrease of BMD and the occurrence of disused osteoporosis. |