| Part I:Summary of three-dimensional finite element analysisObjective:To establish the three-dimensional finite element model of scaphoid waist fracture with palmar retrograde and antegrade screws fixation,analyze and compare the biomechanical stability of scaphoid waist fracture post retrograde and antegrade screws fixation, in order to provide biomechanical basis for retrograde screws fixation.Methods:We obtained the Structural information of the distal ulna and distal radius and the carpal and the proximal of Metacarpal bone through the CT scan, and established the scaphoid waist fractures model by using the three-dimensional finite element software. Then, as a reference to the clinical surgical procedures, we established the different angles retrograde screw fixation model and the three-dimensional finite element model of post antegrade fixation while screws were placed along the axis line of Scaphoid. We simulated the forces of scaphoid waist fractures post screw fixation,and analyzed the horizontal displacement of fracture and the maximum stress that screws suffered of retrograde fixation while Screw fixation in different locations and compared with antegrade fixation.Results:In all retrograde screws fixation models, the stress that screws suffered and the horizontal displacement of fracture were both minimum while screws were placed along the axis line of Scaphoid. Among all the models, the stress that screws suffered and the horizontal displacement of fracture were both minimum in all antegrade screws fixation models, and was very closed to the retrograde screws fixation models while screws were placed along the axis line of Scaphoid.Conclusion:In all antegrade fixation model,the screw in the axis of the scaphoid is the most stable model, and biomechanical stability of retrograde and antegrade screws fixation had no significant difference while screws are placed along the axis line of Scaphoid.Part II:Summary of Comparative Clinical StudyObjective:To compare the Clinical efficacy of two types of internal fixation methods via palmar approach with Herbert screws retrograde internal fixation and anterograde internal fixation the treatment of unstable scaphoid waist fractures. Methods:A prospective study were carried out, from June 2007 to May 2010,42 cases of scaphoid waist fractures were randomly allocated into two groups according to hospitalization order and Random number table.Retrograde internal fixation group patients were treated with Herbert screw fixation from the proximal pole to the distal pole via palmar approach(group A, n= 19), and anterograde internal fixation group patients were treated with Herbert screw fixation from the distal pole to the proximal pole via palmar approach(group B, n= 23). Two groups were to be wound healing after surgery underwent fumigation treatment of traditional Chinese medicine. Patient demographics were similar between the groups (P>0.05), and the minimum follow-up was 6 months. Union was determined with use of plain radiographs or computed tomography. In addition, time to union, union rates, the amount of bleeding and operation time were recorded. The results were evaluated using the clinical scoring system of Cooney.Results:All cases were followed up for 6 months to 18 months, average 9.5 months.Seventeen of the nineteen fractures treated with fixation from the proximal pole healed, at a median of 11.73±2.46 weeks, and sixteen of the Twenty-three fractures treated with fixation from the distal pole to the proximal pole healed, at a median of 14.61±3.74 weeks. The rate of union was significantly higher (P＜0.05) and the median time to healing was significantly shorter (P<0.05) for the scaphoid fractures treated with the fixation from the proximal pole. The outcome according to the clinical scoring system of the fixation from the proximal pole to the distal pole was excellent in 9, good in 7, fair in 1, and poor in 2 patients. The fixation from the distal pole to the proximal pole was excellent in 8 good in 7, fair in I, and poor in 7 patients. Comparison of the clinical of two groups was statistically significant (P<0.05).Conclusion:As to the healing rate and healing time, via palmar approach with Herbert screws retrograde internal fixation is superior to anterograde internal fixation which provides a reference for the clinical treatment of unstable fractures of scaphoid waist. |
PDF Full Text Request