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The technical deficiencies in traditional medical imagining methods limit the study of
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Ankle , Ankle Joint , Biomechanical Phenomena , Range of Motion, Articular , TechnologyABSTRACT
Objective To investigate the translation and rotation of healthy elbow joints during active flexion and extension, so as to provide references for the treatment of elbow instability and injuries. Methods Ten healthy subjects with no history of upper extremity trauma were recruited. Dual fluoroscopic imaging system (DFIS) was applied to quantify six-degree-of-freedom (6-DOF) kinematics of humeroulnar and humeroradial joint from full extension to maximum flexion in supination position. Correlation analysis was used to evaluate the relationship between the 6-DOF kinematics of the elbow joint. Results Valgus angle of humeroulnar joint gradually decreased from 15.2°±3.1° to 5.3°±2.3° with the flexion increasing. Valgus angle of humeroradical joint gradually decreased from 19.7°±4.2° to 8.2°±2.4° from full extension to maximum flexion. The valgus angle of humeroulnar and humeroradial joint was linearly related to the flexion angle during flexion and extension. The internal rotation of humeroulnar joint was quadratic nonlinearly related to the flexion angle during motion. The maximum internal rotation of the ulnar was 4.0°±4.9° at 110° flexion, and the maximum external rotation was 5.1°±4.2°. The internal rotation of humeroulnar joint gradually increased from 3.2°±16.0° to 27.2°±18.0°. Conclusions During normal flexion and extension of the elbow, the valgus angle of humeroulnar joint decreased linearly, while the internal and external rotation angle showed a nonlinear change, which first rotated internally and then rotated externally. The valgus angle of humeroradial joint decreased linearly and the internal rotation angle increased linearly. Therefore, humeroulnar joint is not a hinge joint during elbow flexion and extension. There is a kinematic difference between humeroulnar joint and humeroracial joint. For clinical treatment of complex elbow injuries, elbow instability and elbow replacement, different motion characteristics in joints should be considered to improve the outcome after surgery.
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Objective To observe the obstacle of mandible to the cervical spine with the aid of dual fluoroscopic imaging system, explore the optimal perspective Methods of in vivo kinematics of cervical spine, and verify the feasibility of cervical in vivo kinematic researches. Methods A dual fluoroscopic imaging system composed of two C-arms placed in different angles was utilized. X ray images of the cervical spine for five healthy volunteers (4 male, 1 female) with standing, flexion extension, twisting and bending positions were obtained with the C-arms in the angle of 90°, 60°and 45°, respectively. The obstacles of mandible to the cervical spine in different positions were compared and the obstacle degree of mandible to the cervical spine was evaluated to screen the optimal perspective Methods. The perspective images under conventional head rotation and coaxial trunk rotation were collected during cervical twisting to compare the obstacle of mandible to cervical images. Results There were significant differences in mandibular obstacle degrees among the three angles measured in standing, flexion-extension, twisting and bending positions（P<0.05）. With two C-arms in 45°, the cervical spine was best imaged with the least obstacle. With two C-arms in 60°, significant differences could be found between the coaxial trunk rotation and the head rotation group. Conclusions For in vivo kinematics study of cervical spine, the obstacle of mandible to the cervical spine can be minimized with C-arms of dual fluoroscopic imaging system in 45°, and the coaxial trunk rotation can decrease the mandibular obstacle degrees as compared with the head rotation, which satisfy the requirement of 2D-3D image matching.