Objective To review the biomechanics of internal fixators for proximal humeral fractures, and to compare the mechanical stabil ity of various internal fixators. Methods The l iterature concerning the biomechanics of internal fixators for proximal humeral fractures was extensively analyzed. Results The most important things for best shoulder functional results are optimal anatomical reduction and stable fixation. At present, there are a lot of methods to treat proximal humeral fractures. Locking-plate exhibites significant mechanical stabil ity and has many advantages over other internal fixators by biomechanical comparison. Conclusion Locking-plate has better fixation stabil ity than other internal fixators and is the first choice to treat proximal humeral fractures.
ObjectiveTo investigate the accuracy of the two-dimension computer-aided surgery navigation system in the lumbar pedicle screw fixation on recombinant CT section after operation. MethodsBetween February 2011 and April 2013, 218 patients undergoing lumbar spinal pedicle screw fixation were divided into 2 groups:two-dimension computer-aided surgery navigation system was used in 95 cases (the navigation group) and X-ray fluoroscopy assistant technology in 123 cases (the fluoroscopy assistant group). There was no significant difference in age, gender, and type of disease between 2 groups (P>0.05). The mean operating time, blood loss volume, and fluoroscopy times, and the one-time success rate of pedicle screw implant were observed. The sagittal screw angle (SSA), the relationship between the pedicle cortex and screw, the accuracy rate of pedicle screw, and the sagittal angle on both sides (SBA) were observed. ResultsA total of 504 screws were inserted in navigation group, 432 (85.7%) were inserted successfully at first time and 472 (85.7%) were inserted successfully at end time. A total of 656 screws were inserted in fluoroscopy assistant group, 474 (72.3%) were successfully inserted at first time, and 563 (85.8%) were inserted successfully at end time. There were significant differences in the one-time success rate and final success rate of pedicle screw implant between 2 groups (χ2=30.19, P=0.00; χ2=18.16, P=0.00). There was no significant difference in the mean operating time and the blood loss volume of pedicle screw implant between 2 groups (t=0.88, P=0.38; t=1.47, P=0.14); but the fluoroscopy times of pedicle screw implant in navigation group 0.7±0.3 were significantly less than that in fluoroscopy assistant group 1.5±1.0 (t=-8.09, P=0.00). The SSA and SBA in navigation group[(3.7±0.9)° and (1.7±0.8)°] were significantly less than those in fluoroscopy assistant group[(6.0±1.7)° and (3.5±1.6)°] (t=-26.92, P=0.00; t=-22.49, P=0.00). ConclusionThe sagittal screw angle and accuracy of pedicle screw implant can be significantly improved using the two-dimension computer-aided surgery navigation system in lumbar posterior fixation.