| Background:Tile C pelvic fractures are one of the most serious types of pelvic fractures,how can minimally invasive surgery be challenging,we have investigated and proposed a novel minimally-invasive treatment using an anterior internal fixation system combined with sacroiliac screws.We designed this study aimed to investigate the biomechanical properties and clinical effect of this treatment.Objectives:1.To study the safety channel parameters of screws in the anterior internal fixator system.2.To compare the biomechanical properties of different fixation models in tile C3 pelvic facture,using an internal fixation system or a locking plate screw system combined with sacroiliac screws.3.To investigate the clinical effect of treating Tile C pelvic fractures by anterior internal fixation system combined with sacroiliac screws.Methods1.Finite element models of normal pelvis were built,simulated the screws penetrating of the anterior internal fixation system,and measured the screws safety channel parameters.2.Different fixation finite element models in tile C3 pelvic facture using two-screwed,three-screwed,four-screwed anterior internal fixation system and locking plate screw system combined with sacroiliac screws were established.600N stress was applied vertically to S1 vertebral endplate,the displacement and stress distribution of pelvis and internal fixations were compared and analyzed.3.Sixteen fresh adult cadaver pelvic specimens were randomly separated into four groups named A,B,C and D,specimens were respectively stabilized using a two-screwed,three-screwed,four-screwed anterior internal fixator and a locking plate screw system with sacroiliac screws.All pelvic facture models were tested in both standing and sitting positions using a biomechanical testing machine.Vertical loads of 600 N were applied increasingly at lumbar segment 5.Shifts of bilateral sacroiliac joints and pubis rupture were measured.4.A retrospective review was performed of 14 patients with Tile C pelvic fracture that had received operative treatment using internal fixation system or a locking plate screw system combined with sacroiliac screws from May 2017 to December 2018.Results1.Screws safety channel parameters of the anterior internal fixation system:the length of screw in ilium was 114.44 d±4.07mm in male and 107.59±8.34mm in female.The diameter of screw in ilium was 11.71±0.52mm in male and 10.01±0.55 mm in female.The distance between screw and anterior inferior iliac spine was 5.51±0.99mm in male and 5.58±1.01mm in female.The angle between screw and human coronal plane was 55.79±2.44° in male and 50.62±3.05° in female.The angle between screw and human sagittal plane was 26.5 8±1.04° in male and 24.45±1.87° in female.The angle between screw and human horizontal plane was 64.88±3.67° in male and 58.05±3.10° in female.The length of screw in pubic was 47.02±1.96mm in male and 39.81±3.84mm in female.The diameter of screw in pubic was 7.12±0.39 mm in male and 6.11±0.37mm in female.The distance between screw and symphysis pubis was 10.12±0.71mm in male and 10.05±0.82mm in female.The results of distance between screw and anterior inferior iliac spine or symphysis pubis,for comparisons between male:female,P>0.05.The results of other parameters,for comparisons between male:female,P<0.05.2.Biomechanical analysis of finite element pelvic model:Use of a two-screwed,three-screwed,or four-screwed anterior internal fixation system or a locking plate screw system with sacroiliac screws effectively stabilized Tile C3 pelvic fractures.The fixed pelvic models were compared with the normal pelvic model,In the standing position,the maximum displacement was increased by 66.51%,65.36%,35.16%,35.47%.the maximum stress was increased by 201.78%,130.65%,100.82%,99.03%.In the sitting position,the maximum displacement was increased by 9.1%,11.04%,5.57%,8.59%.the maximum stress was increased by 157.73%,118.02%,98.32%,93.16%.3.Biomechanical analysis of pelvic specimens:In the standing position,the results of shifts in the sacroiliac joints were:Group C<Group D<Group B<Group A.The results of shifts in pubis ruptures were:Group D<Group C<Group B<Group A.In the sitting posture,the results of shifts in the sacroiliac joints were:Group C<Group D<Group B<Group A,while the shifts in the pubis ruptures were:Group D<Group C<Group B<Group A.4.Clinical cases analysis:To compare with the group treatment using the locking plate screw system combined with sacroiliac screws,the group treatment using the anterior internal fixation system combined with sacroiliac screws had advantages in hospital stays,operative time,bleeding volume,blood transfusion volume and length of incision,the differences were statistical significance(P<0.05).The difference in Matta evaluation grade after operation and Majeed functional scores in the final follow-up visit were not significant difference(P>0.05).Conclusion1.Pay attention to gender difference between male and female,control the screws diameter,length,position and direction,the screws of anterior internal fixation system can be safely inserted in the superior iliac spine and pubic.2.Use of an anterior internal fixation system combined with sacroiliac screws effectively stabilized Tile C3 pelvic fractures.Among the options tested,a two-screwed internal fixator combined with sacroiliac screws was easier to operate.The stability of specimens increased as the number of screws in the internal fixator increased.3.The anterior internal fixation system combined with sacroiliac screws can safely and effectively treat Tile C pelvic fractures,with the advantages of minimally invasive,simple operation,short operative time,less bleeding,fewer complications,short hospital stays and good postoperative functional recovery. |
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