To explore the clinical efficacy of percutaneous pedicle screw short segment internal fixation with or without the intermediate screw in the treatment of Magerl A3 thoracolumbar fractures with low bone mineral density.Patients with Magerl A3 thoracolumbar fracture underwent percutaneous pedicle screw short segment internal fixation from January 2017 to July 2020 were retrospectively analyzed, 93 cases met the diagnosis and inclusion criteria, 9 cases were excluded according to the exclusion criteria, and the remaining 84 cases obtained complete imaging follow-up data. There were 38 males and 46 females, the age ranged from 56 to 73 years old with an average of (64.78±7.12) years old, bone mineral density (BMD) ranged from 0.61 to 0.89 g/cm3 with an average of (0.73±0.14) g/cm3, the follow-up time was 11 to 25 months with an average of (17.58±6.12) months. There were 45 cases in group A with intermediate screw and 39 cases in group B without intermediate screw. The operation time and intraoperative blood loss were recorded, Oswestry Disability Index (ODI) and visual analogue scale (VAS) were used for clinical evaluation. The Cobb angle, vertebral wedge angle (VWA) and anterior vertebral body height (AVBH) were measured by X-ray after the operation. The corrected loss of the above parameters was calculated.There were 5 cases of screw loosening in 84 patients (2 cases in group A and 3 cases in group B, P>0.05). There were significant differences in operation time and intraoperative blood loss between two groups(P<0.01). Clinical effects of two groups were good, postoperative VAS and ODI after operation obviously improved, there was no significant difference between two groups during all follow-up periods (3 days, 1 month after operation and the final follow-up) (P>0.05). Three days after the operation, the image evaluations (Cobb angle, VWA and AVBH) were significantly improved (P<0.05), but significant reduction loss was observed in both groups at 1 month after the operation and at the final follow-up (P<0.05). At the final follow-up, the loss of Cobb angle, VWA and AVBH in group A were (5.26±4.18) °, (4.63±3.80) ° and (9.54±8.71)%, respectively;group B was (6.01±4.34) °, (6.55±6.21) ° and (11.67± 9.95)%, respectively;however, there was no significant difference in reduction loss between the two groups(P>0.05).Although the curative effect of the patients is satisfactory, the stability of the patients can not be improved by increasing the middle injured vertebra screw placement, the two groups of percutaneous short segment internal fixation can not resist the reduction loss of Magerl-A3 thoracolumbar fracture with low bone mineral density. Because the injured vertebra screw increases the operation time and intraoperative blood loss, it is not significant to use the intermediate screw for the elderly Magerl A3 thoracolumbar fractures with low bone mineral density.