Factors Analysis Of Screw Penetration Of Proximal Humeral Fracture Surgery And Imaging Studies Of Intraoperative Fluoroscopy

Part One A binary Logistic regression analysis of screw penetration after proximal humeral fracture surgery?Objectives? To analyze the incidence of screw penetration after surgery of proximal humeral fracture(PHF) and to explore its prognostic factors and the relevant preventive countermeasures.?Methods? 187 patients who had open reduction-internal fixation with locking plates of PHF in our department from June,2006 to June,2012 were analyzed retrospectively. They were 78 males and 109 females, 55.9 years averagely(18~88 years). All the patients were divided into a screw penetration group and a non- screw penetration group according to their shoulder X-ray during the follow-up period, which were taken as the dependent variable.We used gender, age, fracture type of Neer, fracture of medial cortex, bone mineral density, time interval from trauma to surgery, bonegraft, the quality of reduction,screw number in the humeral head, medial column support as covariates. Univariate logistic regression analysis was adopted to pick up the factors whose P<0.05, which were then used to perform multiple stepwise logistic regression.?Results? They were followed up for a mean time of 17.8(10 to 45)months.27 patients had screw penetration(incidence,14.4%). The univariate logistic regression analysis showed that fracture type of Neer, fracture of medial cortex, bonegraft, the quality of reduction,screw number in the humeral head, medial column support, fracture of medial cortex×medial column support had a significant association with screw penetration(P<0.05). The multiple stepwise logistic regression showed that fracture type of Neer[The results of Neer 3-part fracture/ 2-part?4-part fracture/ 2-partwere(P=0.028,OR=4.406,95%CI(1.176~16.515))?(P=0.004,OR=7.799,95 % CI( 1.924 ~ 31.620)) respectively], fracture of medial cortex[ P=0.008,OR=0.287,95%CI(0.114~0.718)]were key factors affecting screw penetration.?Conclusions? Fracture type of Neer and fracture of medial cortex may be the chief prognostic factors affecting screw penetration after the surgery of PHF. The best individualized treatment should be made to reduce the incidence of screw penetration.Part Two the Imaging Studies of Intraoperative Fluoroscopy to avoid Screw Penetration of Proximal Humeral Fracture Surgery? Objectives ? We conducted an imaging studies simulating intraoperative fluoroscopy on cadaveric proximal humeri to find out the best angle range to recognize the penetration of each humerus head screw. And then determine the the best angle combination to reduce the incidence rate of intraoperative screw penetration.?Methods? AO philos plates were fixed to six cadaveric proximal humeri. Each head screw was exchanged to perforate the joint surface with 1mm of its tip turn by turn. We got radiographys of each humerus with each perforated screw under the angles as below. Keep the shoulder stay, and take one photo each 5o when the C-arm rotated 180 o on cross plane. Repeat to take photo when the C-arm rotated 120 o on coronal plane. Convert the angle to internal/external angle(anteriorposterior) and abduction angle(axial). Two orthopaedic doctor read the photo to determine penetration or not. And find out the best angle range for each head screw and the best angle combination for all screws.?Results? The best angle ranges(anteriorposterior+ axial) for screw No.1~9 were, respectively,(ap I35 o ~ap E20 o + ax A 25 o ~ ax A 75o),(ap I30 o ~ap E30 o + ax A 30 o ~ ax A 75o),(ap I30 o ~ap E5 o + ax A 5o ~ ax A 50o),(ap I20 o ~ap E20 o + ax A 0o ~ ax A 40o),(ap I65 o ~ap I5 o + ax A 5o ~ ax A 70o),(ap I0 o ~ap E60 o + ax A 0o ~ ax A70o),(ap I15 o ~ap E20 o + ax A 10 o ~ ax A 45o),(ap I30 o ~ap I5 o +none),(ap E5 o ~ap E35 o +none). The best angle combination for all screws was :( ap I 20o/ap I 0o/ap E 20o) +( ax A 30 o / ax A 50o).?Conclusions? The screw penetration of proximal humeral fractures surgical can be ignored easily. The best angle combination for all screws was :( ap I 20o/ap I 0o /ap E 20o) +( ax A 30 o /ax A 50o). On the anteriorposterior radiography, the proximal screws can be found more easily than the distal ones. The front screws can be found more easily on internal angles(anteriorposterior), while the rear screws on external angles. On the axial radiography, No.(8,9) screws can be found hardly. Though the best angle ranges for the rest screws were same almost, the angles for the proximal screws were a bit large than the ones for the distal screws.