ABSTRACT
BACKGROUND: At present, the prosthesis is made by three steps: Taking, trimming and shaping. Because the process of trimming is manual, it is closely related to the experience and technology of clinical technicians. If the prosthesis is not beautiful, it is difficult to make full contact between the receiving cavity and the residual limb. OBJECTIVE: To collect MRI data of thigh in healthy volunteers, evaluate the anatomical symmetry of thigh amputation range (10-25 cm above knee joint space), and establish MRI data as a database so as to provide reference data for patients with lower limb amputation to match the appropriate prosthesis after operation. METHODS: Totally 40 healthy volunteers were recruited and basic information was collected, including age, height, weight, the circumference of the knee, the circumference of the knee at 5 cm, the circumference of the knee at 10 cm, and the circumference of the knee at 15 cm. All volunteers signed the informed consent. This study was approved by the Hospital Ethics Committee. Three-dimensional reconstruction was carried out in thigh amputation range. Taking the surface area and volume of the model as parameters, the thighs of each volunteer were anatomically measured. Three-dimensional reverse engineering software was used to analyze the three-dimensional deviation of the measurement results so as to conduct quantification and visualization of the thigh symmetry. RESULTS AND CONCLUSION: (1) Self symmetric analysis: Regarding the surface area, the maximal percent difference between the left and right thigh amputation was no more than 0.56% (P=0.109). Regarding the volume, the maximal percent difference between the left and right thigh amputation was no more than 1.19% (P=0.182). Results of the three-dimensional deviation analyses showed that the maximal mean negative deviation was -1.47 mm, while the maximal mean positive deviation was 1.14 mm. Moreover, the three-dimensional deviation distribution of 40 subjects was within 2 mm (78.02%), between 2.1 and 3.0 mm (20.97%), and more than 3 mm (1.01%). (2) Allogeneic symmetric analysis: Results of the three-dimensional deviation analyses showed that the maximal mean negative deviation was -1.97 mm, while the maximal mean positive deviation was 1.89 mm. (3) The results confirmed that adult bilateral thigh amputation range has a high degree of anatomical symmetry. When differences between two adults' right thighs are no more than 2 cm in the circumference of the knee, the circumference of the knee at 5 cm, the circumference of the knee at 10 cm, and the circumference of the knee at 15 cm, their surface profiles of thigh amputation ranges are considered to be highly similar, but are not associated with gender, height and weight.
ABSTRACT
Objective To investigate whether a 3D printed model of the contrlateral healthy distal radius, especially its articular accuracy, helps anatomical reduction and precise reconstruction of the fractured distal radius. Methods The CT data of bilateral radii were collected from 15 normal volunteers ( 11 males and 4 females with an average age of 22. 8 years ) between November and December 2016. After 3D reconstruction of the bilateral distal 1/3 radii, solid 3D models of left radius were mirrored and generated by 3D printing. The data of right radii ( reference group ) were compared with the data of the solid 3D models of left radius acquired through a 3D scanner ( test group ) using deviation analysis. Results The maximum volume difference between the 3D printed model and the contralateral radius was 6. 86％. The average volume of the reference group was 19, 165. 82 ± 3, 250. 50 mm3 and that of the test group 19, 310. 65 ± 3, 305. 15 mm3, showing no statistically significant difference between the 2 groups ( t= -0. 941, P=0. 363 ) . The maximum surface area difference was 3. 84％ between the 2 groups. The average surface area of the reference group was 5, 075. 80 ± 549. 34 mm2 and that of the test group 5, 139. 43 ± 572. 48 mm2, showing a signifi-cant difference ( t= -2. 451, P=0. 028 ) . The 3D deviation analysis showed a mean positive deviation of 0. 37 ± 0. 10 mm and a mean negative deviation of 0. 30 ± 0. 07 mm. The maximum mean square root was 0. 65. The 3D deviation was distributed mainly within 1 mm interval, with a distribution frequency of 96. 27％. Conclusions A 3D printed model prepared by high precision equipment is accurate enough to guide reconstruction of distal radius fractures in adults. In the treatment of complex fractures of the distal radius, a 3D printed model of the contralateral healthy distal radius can be used as a reference to achieve anatomical reduction and precise reconstruction of the fractured distal radius.