| BackgroundThe sacroiliac joint dislocation or fracture dislocation is one of completely unstable pelvic ring, but in surgical treatment, to restore the important role of the stability of the sacroiliac joints, especially in the mechanical strength of the fixed implant, and there is no cause enough attention. At present the sacroiliac screws fixation is the most common clinical treatment sacroiliac joints dislocation, Some studies show the sacroiliac screws its biomechanical strength relative satisfactory,but clinical complications is more,such as fracture to the shift and fracture nonunion.With spinal-pelvic fixed model has been the most scholars and recognition, and gradually be replaced the sacroiliac fixed trend, One single nail-rod system is a kind of posterior spinal-pelvic fixed models, but single nail-rod system posterior used to treat the sacroiliac joint dislocation of the biomechanical, clinical data rarely reported.Objective To test the biomechanics of the single nail-rod system fixation of sacroiliac joint dislocation through embalmed cadavers, and comparing with the iliosacral screws. We compared the pelvic biomechanical intensity of the single nail-rod system fixation and the iliosacral screws fixation, and try to provide a biomechanical basis and theoretical basis for the clinical application of single nail-rod system fixation of sacroiliac joint dislocation。Methods1、Biomechanical study The first step:Prepare specimens Take12adult anticorrosive bodies, men six bodies, female six bodies,Since the L4、5and double leg below the1/3junction cross-sectional bodies, to get12pelvic specimens.The second step:Damage model established To cut ties with side sacroiliac joints of the ligament in structure and sacrotuberous ligament sacrospinous ligament, seprate facies auricularis, Truncate pubic symphysis, and make the sacroiliac joint dislocation, pubic symphysis separation model. The third step:Damage model fixed1), Single nail-rod group:Clear S1pedicle screws site and twist into the screws, strip the soft tissue in the spinailiacaposteriorsuperior, expose the needle points, install Schanz nail,and model form and install the connection rod.2),Sacroiliac screws group:Confirm the intersection point in spinailiacaanteriorsuperior and spinailiacaposteriorsuperior the third after the attachment. The hollow drill with the guide bored after the needle, twist into the proper length7.3mm in diameter hollow cancellous screws.The specimens implanted 1sacroiliac screws.3) Fixed Pubic symphysis of two groups model by six-hole reconstruction plate. The Fourth Step:Biomechanics of measurement:All the pelvic specimens are tested with electronic universal test machine,simulated the human body standing posture,and fixed on experimental mechanics machine,then measuring mechanical properties between the sacroiliac screws group and single nail-rod group. The Fifth Step:Data Statistic Analysis:Measurement data indicated by x±s,Statistics with SPSS11.5statistical software package (version11.5, Chicago, IL, USA), P0.05for differences with a statistical significance.2、Review clinical material Set single nail-rod system clinical indications, collect16cases of sacroiliac joint dislocation of patients with clinical data,and use Mears image evaluation standard and pelvic fractures Majeed curative effect to assess data statistics and score.Results In the same load, the displacement, axial stiffness,utimate-load and yield-load of the single nail-rod group are larger than the sacroiliac screws group (P <0.05). In16patients were followed up for an average of23.2months (3-45months). According to the image of the Mears standard, anatomical replacement13cases,3cases satisfaction. Pelvic fractures Majeed score from60to100points,82points average; TileC1type of fractures is81.8%, TileC2type80.0%.Conclusions Prompt and sacroiliac screws comparison, the single nai-rod was great application for the sacroiliac joint dislocation, its more reliable strength and clinical curative effect. |
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