BACKGROUND:In clinic, monosegmental pedicle screw fixation via the fractured vertebrae is commonly used for the treatment of thoracolumbar fracture. Studies have confirmed that the spinal stability is strengthened through bilateral pedicle screw fixation via fractured vertebrae, but some studies suggest that monosegmental pedicle screw fixation via fractured vertebrae can increase the spinal stability, and the conclusion lacks of the supports of biomechanics.
OBJECTIVE:To evaluate the biomechanical properties of monosegmental pedicle screws fixation via fractured vertebrae for thoracolumbar fracture.
METHODS:Eight cadavers’ thoracolumbar specimens (T11-L3) were provided by the Department of Anatomy, Yangzhou University School of Medicine. Saw was used to transect 2/3 of the vertebrae in order to make complete experimental thoracolumbar specimens. Eight specimens were divided into two group;beyond-fractured vertebrae fixation group and monosegmental fixation via fracture vertebrae group. The specimens in the two groups were treated with adjacent vertebral four screw fixation beyond fractured vertebrae and adjacent vertebral four screw fixation+monosegmental pedicle screw fixation via fractured vertebrae respectively.
RESULTS AND CONCLUSION:After thoracolumbar fracture, the differences between beyond fractured vertebrae fixation and monosegmental pedicle screw fixation via fractured vertebrae were as fol ows:load-strain relationship 12%, load-displacement relationship 11%, strength 18%, axial rigidity 11%, torsional mechanical properties 11%and pul out test 1.8%, and there were no significant differences between two groups (P<0.05). The biomechanics performance of monosegmental pedicle screw fixation via fractured vertebrae was more superior to that of pedicle screw fixation beyond the fracture vertebra for thoracolumbar fracture.

Objective To study the difference between intensity-modulated radiation therapy (IMRT) and three dimensional conformal radiation therapy (3D-CRT) for pelvic radiation of post-operative treatment with gynecologic malignant tumor. Methods A prospective investigation study was conducted on 183 patients of post-operative patients with whole pelvic radiation therapy of cervical cancer or endometrial cancer in Zhejiang Cancer Hospital [IMRT group (n=85) and 3D-CRT group (n=98)] from Oct. 2015 to Oct. 2016. The two groups received same dose (45 Gy in 25 fractions). Comparison of two groups with radiation dosimetry:the score according to the Radiation Therapy Oncology Group (RTOG) acute radiation injury grading standards before and after radiotherapy reaction, the score from functional assessment of cancer therapy scale-cervix (FACT-Cx) scale and expanded prostate cancer index composite for clinical practice (EPIC-CP) scale were also analyzed. Results (1) There were no significant effect with age, culture level, family economic condition and ratio of radiochemotherapy between two groups (all P>0.05). (2) Dosimetric comparison for IMRT vs 3D-CRT:the average dose of planning target volume (PTV) decreased(46.1 ± 0.4) vs(46.4 ± 0.5)Gy, V45 dose percentage increased(95.2 ± 1.0)%vs (93.3 ± 2.0)%, intestinal bag dose of V40 decreased(24.4 ± 6.8)%vs (36.5 ± 15.9)%, rectal V40 dose percentage decreased(73.9 ± 12.3)%vs (85.4 ± 8.4)%, and lower rectal V45 dose percentage(32.8 ± 13.4)%vs (71.5 ± 13.7)%, bladder V40 dose percentage decreased(55.5 ± 13.0)% vs (84.4 ± 13.0)%. Bone marrow V20 lower:(67.9 ± 5.4)% vs (79.5 ± 6.6)%, V10 lower:(82.1 ± 6.0)% vs (86.3 ± 6.6)%; there were significant differences (all P<0.05). There was no significant difference between the dose of V45 in the intestinal pouch and bladder (P>0.05). (3) Acute radiation injury classification for IMRT vs 3D-CRT:big or small intestine:Ⅱ-Ⅲreaction [13%(11/85) vs 24% (24/98); χ2=3.925, P=0.048], there was significant difference. Bladder: Ⅲ reaction [19% (16/85) vs 26% (25/98); χ2=1.171, P=0.279], there was no significant difference. Radiochemotherapy of bone marrow suppression:Ⅲ-Ⅳreaction (14/20), the incidence rate [26%(14/54) vs 31%(20/65);χ2=0.339, P=0.562], the difference was not statistically significant. (4) Quality of life scale by FACT-Cx scale in IMRT vs 3D-CRT:there were no significant difference before radiotherapy (82 ± 16 vs 85 ± 16;t=1.279, P=0.203), while there was significant difference after radiotherapy (76 ± 14 vs 71 ± 18;t=-2.160, P=0.032). EPIC-CP scale score:before radiotherapy they were (16±7 vs 15±6;t=-0.174, P=0.862) ,but after radiotherapy (18±7 vs 22± 7; t=3.158, P=0.002), there was significant difference between them. Before and after radiotherapy, the increased EPIC-CP scale of the IMRT group vs 3D-CRT group were 3 ± 4 and 6 ± 4, the 3D-CRT group was significantly higher, the difference was statistically significant (t=5.500, P=0.000). Conclusion IMRT has shown that there are a significant benefit for the post-operative patients with cervical cancer and endometrial cancer compared to 3D-CRT.