Measurement of femoral neck anteversion of developmental dislocation of hip in children by 3D printing technique / 中国骨伤

OBJECTIVE@#To explore the method and accuracy of measuring the femoral neck anteversion in children with developmental dislocation of the hip by using 3D printing technology, so as to find out the method of measuring the femoral neck anteversion accurately and guide the formulation of the operation plan.@*METHODS@#From June 2016 to September 2018, 17 patients with unilateral developmental dislocation of the hip were enrolled in the study, including 2 males and 15 females, aged 2 to 13 (5.47±0.81) years old, 11 on the left and 6 on the right. The methods of CT, 3D printing and intraoperative anteversion of femoral neck were used to measure the anteversion of femoral neck respectively. The intraoperative measurement was used as the standard reference value forstatistical analysis, and the accuracy of the first two methods was compared.@*RESULTS@#The average value of CT was (36.00±1.66)°, the average value of model method was(43.91±1.62)°, and the average value of intraoperative method was(44.21±1.62)°. There were significant differences in CT measurement, model measurement and intraoperative measurement(0.05).@*CONCLUSION@#Compared with the traditional CT method, the 3D printing model method is simpler, more accurate and more repeatable, and can simulate the operation before operation. It is an ideal method to measure the femoral neck anteversion.

Experimental study on internal fixation with screws through femoral epiphyseal plate / 中国骨伤

<p><b>OBJECTIVE</b>To explore the effect of internal fixation with screw through femoral epiphyseal plate on growth in- hibition via an experimental study.</p><p><b>METHODS</b>Forty New Zealand rabbits were randomly divided into 4 groups and 10 rabbits in each group. Epiphyseal plate was injured by penetrating of screws, and the size of damage area was controlled by changing the number of threads. Group A: blank group; group B: injury area accounted for 4% of the epiphyseal plate; group C: injury area accounted for 6%; group D: injury area accounted for 8%. The internal fixation was removed after 2 weeks, and the results were observed with X-ray film for 4 groups to judge the complications such as early closure of epiphyseal.</p><p><b>RESULTS</b>In each group, there were no statistical differences in the length of the femoral neck, the diameter of femoral neck, the diameter of the femoral head, and the epiphyseal plate closure time. The growth speed of the length and diameter of the femoral neck, as well as the diameter of femoral head, were quicker on the early phase, and the speed was slowest when the epiphyseal plate was being closed.</p><p><b>CONCLUSION</b>The injury area of epiphyseal plate under 8% is safe for its growth. Because no evidences demonstrate the growth inhibition of epiphyseal plate, the screws can be used for rabbit epiphyseal plates.</p>

An imaging study on location of the anterior border of facets and the posterior border of vertebral bodies in lower cervical spine / 中国骨伤

<p><b>OBJECTIVE</b>To explore the location of the anterior border of facets and the posterior border of vertebral bodies in lower cervical spine,and to provide a quantitative data to evaluate the correct length of transarticual screws in lower cervical spine during procedure.</p><p><b>METHODS</b>One hundred standard lateral X-ray films and fifty CT films on cervical spine were used to measure the distance of the anterior border of facets and the posterior border of vertebral bodies in lower cervical spine. HS, HM and HI were defined as parameters, which means the distance between the anterior border of the superior (HS), median (HM) and inferior (HI) part of facets and the posterior border of corresponding vertebral bodies. The value will be negative if the anterior border of the facet located before the vertebral body.</p><p><b>RESULTS</b>'HS > HM > HI' was found in all facets in lower cervical spine. The anterior border of the facet in C(3,4) located before the posterior border of the vertebral body of C3. The anterior border of C(4,5) and C(5,6) was inclined to posterior. The anterior border of C(6,7) located after the posterior border of the vertebral body of C6. The pattern of HS increased from C(3,4) to C(6,7), the minimal (0 +/- 0.25) mm and the maximal (2.91 +/- 1.05) mm. The tendency of HM raised from C(3,4) to C(6,7), the minimal (-1.57 +/- 0.53) mm and the maximal (1.54 +/- 0.39) mm. The pattern HI added from C(3,4) to C(6,7), the minimal (-2.03 +/- 0.40) mm and the maximal (1.08 +/- 0.70) mm.</p><p><b>CONCLUSION</b>During the implantation of the transarticular screws, the tip of the screws should be 0-2 mm before the posterior border of the vertebral body of C3 at C(3,4), 0-2 mm after that of C4 at C(4,5), 0.5-2.5 mm at C(5,6) and 1-3 mm at C(6,7). The quantitative location between the anterior border of facets and the posterior border of the corresponding vertebral bodies can offer an indirect method to evaluate the correct length of transarticual screws in lower cervical spine during procedure.</p>