Objective To develop a new type of tail cap for closing the tail of the central hole of the interlocking intramedullary nail so as to reduce difficulty in implantation of the tail cap into intramedullary nail, and ensure the accuracy of implantation, as well as reduce unnecessary operation time. Methods In 2014, the new type of intramedullary nail tail cap (" new tail cap” for short) was successfully developed, and has been granted national utility model patent. A randomized controlled clinical trial was conducted in 34 patients with non pathological femoral shaft fractures treated between August 2014 and March 2016. The patients were randomly divided into groups A and B, 17 patients each group. There was no significant difference in gender, age, side, body mass index, cause of injury, injury to operation time, and fracture AO classification between groups (P>0.05), with comparability. All patients underwent fixation with interlocking intramedullary nail, and the new tail cap and original tail cap were used in groups A and B respectively. The blood loss and operation time during tail cap implantation, fracture healing time, and complications were recorded and compared between 2 groups; the limb function was evaluated by Klemm function evaluation standard. Results The blood loss and operation time during tail cap implantation of group A [(3.5±0.8) mL and (10.57±3.15) s] were significantly less than those of group B [(5.5±1.7) mL and (21.99±6.90) s] (t=–8.281,P=0.010;t=–10.743,P=0.009). All new tail caps were successfully implanted by one-time in group A, and the one-time success rate was 100%; the original tail cap exfoliation occurred in 3 cases of group B, and the one-time success rate was 82.4%. All the patients were followed up 6-16 months (mean, 9.7 months); there was no deep infection, loosening or breakage of internal fixation, and other serious complications. The time of fracture healing was (16.4±3.2) weeks in group A and (15.8±3.5) weeks in group B, showing no significant difference (t=0.514,P=0.611). At last follow-up, according to the Klemm function evaluation standard, the results were excellent in 14 cases and good in 3 cases in group A, and were excellent in 11 cases and good in 6 cases in group B, showing no significant difference between 2 groups (χ2=0.142,P=0.707). Conclusion The new type of femoral intramedullary nail tail cap can simplify operation, shorten operation time, and reduce blood loss, and it has satisfactory effectiveness.
Objective To develop an anatomical locking plate in accordance with the anatomical characteristics of the sternoclavicular joint, which is reliable fixation and easy to operate, so as to provide an ideal internal fixation device for the treatment of sternoclavicular joint dislocation or peripheral fractures. Methods Gross measurement and CT measurement were performed on the 8 adult antiseptic and moist cadaver specimens (16 sides) to measure the parameters of surrounding bone structure of the sternoclavicular joint. The parameters included the thickness of presternum, sternal notch width, anteroposterior diameter of proximal 1/3 of clavicle, upper and lower diameters of proximal 1/3 of clavicle, angle between proximal end of clavicle and presternum in coronal plane, and angle of thoracoclavicular joint at anatomic position forward. According to the anatomical parameters and biomechanical properties of the specimens, the anatomical locking plate was designed and developed. The sternoclavicular ligament and joint capsule of all the specimens were completely cut off to make the sternoclavicular joint dislocation model. The left and right sternoclavicular joint of each specimen were randomly divided into experimental group (anatomic locking plate fixation) and control group (oblique T shape locking plate fixation). The sternoclavicular joint activity and common force mechanism was simulated on the universal mechanical testing machine, and the clavicular distal load test, sternoclavicular joint torsion test, and anti-pulling of steel plate manubrium part test were performed. Results The differences between the anatomical parameters of gross measurement and CT measurement were not significant (P>0.05). In the clavicular distal load test, when the anatomical position perpendicular to the distal clavicle back loading to 20 N, the displacement of loading point in the experimental group was (8.455±0.981) mm, which was significantly less than that in control group [(10.163±1.379) mm] (t=–3.012,P=0.020); the distal clavicle displacement of loading point of experimental group and control group were (5.427±1.154) mm and (6.393±1.040) mm, respectively, showing no significant difference (t=–1.459, P=0.188). In the sternoclavicular joint torsion test, the torque of experimental group was significantly greater than that of control group when the clockwise torsion angle was at 2, 4, 6, 8, and 10 degrees and the counterclockwise torsion angle was at 4, 6, 8, and 10 degrees (P<0.05). The torsional stiffness in the experimental group under clockwise and counterclockwise condition was 0.122 and 0.108 N·m/° respectively, which were significantly higher than those in the control group (0.083 and 0.078 N·m/° respectively) (F=67.824, P=0.000; F=20.992, P=0.002). In the anti-pulling of steel plate manubrium part test, the maximum pullout force of experimental group [(225.24±16.02) N] was significantly higher than that in control group [(174.40±21.90) N] (t=5.785, P=0.001). Conclusion The new type of anatomical locking plate can realize the sternoclavicular joint three-dimensional fixation, and has the advantages of reliable fixation, simple operation, less trauma, superior biomechanical properties, and earlier functional exercise. It may be an ideal internal fixation device in clinical treatment of sternoclavicular joint dislocation or peripheral fractures.