Clinical Application Of Lateral View Of Pelvis Intraoperatively

Objective: Displaced posterior acetabular wall fractures were recommended to be managed by open reduction and internal fixation(ORIF).Reduction of fracture,rigid fixation and early functional exercise usually produced a satisfactory effect of treatment.The operation requires fixing plates by implanting screws around atricular surface.If not redirected during operation,intra-articular screws always leaded to grave consequences such as pain,joint destruction,disability and further surgery.[1,2] To avoid this condition,the intraoperative detection of intra-articular screws was very necessary.The C-arm(2D),intraoperative 3D fluoroscopy(3D),intraoperative auscultation were utilized to avoid the perforation of atricular surface.3-6 The C-arm was the most available way during operation.The objective of this study was to exploring a novel view that detects intra-articular screws effectively and conveniently.The views could correct the intra-articular screws intraoperatively to reduce the complications also shorten operative time reduce exposure radiation.Method: Five cadaveric pelvises were applied in the study.All the specimens were free from fracture,rheumatism,tuberculosis,tumour,implant,or any condition that changed the specimens radiographically.All the hip joints were dislocated and the soft tissue envelope was removed,but the transverse acetabular ligaments and articular cartilage remained so all the operation was under direct visual.A 9-hole-reconstruction plate was fixed on the posterior columns of each acetabulum by six 3.5mm screws.In each group only four screws that implanted in the posterior rim worked as observation subjects(about 7-11 o'clock of the right acetabulum).There are 40 screws implanted along the posterior rim in total.20 screws that violate hip joints were chosen in random.No hip joint was free from the violation of screws.Each hip joint contained 1-3 screws.The screw tips protruded from thearticular surface by 1-2mm.The remaining 20 screws were extra-articular.Two fileset was established.One contains anteroposterior(AP),iliac oblique,obturator oblique views and the other contains lateral views.All the images were observed in a blinded fashion by 3 independent orthopedists.Accuracy,specificity,sensitivity,positive predictive value(PPV),and negative predictive value(NPV)of three observers were calculated totally.Chi-square and Fisher' Exact Test was used to test the statistically differences about the position of the periacetabular screws.Results: The overall accuracy,specificity,sensitivity,PPV,and NPV in anteroposterior(AP),iliac oblique,obturator oblique views was 66%?93%?40%?61% and 86%,94%?97%?92%?92% and 96% in lateral views.There was a statistically difference in three observers' comparisons(P1=0,P2=0.013,P3 =0.02<0.05).First observer identified 18 intra-articular screws correctly through anteroposterior(AP),iliac oblique,obturator oblique views,and 18 intra-articular screws through lateral views.Another one identified 19intra-articular screws correctly through anteroposterior(AP),iliac oblique,obturator oblique views,and 20 intra-articular screws through lateral views.The last observer identified 19 intra-articular screws correctly through anteroposterior(AP),iliac oblique,obturator oblique views,and 19 intra-articular screws through lateral views.In anteroposterior(AP),iliac oblique,obturator oblique views,there was a consensus in 25 of 40 screws which one was identified correctly.In lateral views,there was a consensus in 36 of 40 screws that were identified correctly.Conclusions: Compared anteroposterior(AP),iliac oblique,obturator oblique views with lateral views,lateral images could improve the accuracy of detecting intra-articular screws.The intra-articular screws could be redricted instantly.It reduced the unnecessary iatrogenic injury.