Anatomical Study On The Reliability Of Total Hip Arthroplasty Acetabular Screws

Objective:To investigate the total hip arthroplasty in cement less acetabular prosthesis with an initial fixed safe screw placement region, and the optimal placement site, length. To explore the best placement scheme, and to provide reference for clinical acetabular prosthesis replacement.Methods:Choose10adult cadavers which with complete Department of anatomy, and clear the anatomic relationship between acetabulum with sciatic nerve SN, obturator nerve ON, external iliac vessels EIV, and measure their distance with acetabular, to determine the safe placement area. And select15complete hip structure, divide each acetabulum by the combination of clock scale and earth latitude. Screening safe area and measure the acetabular bone thickness through it. The data were analyzed with statistics, outcome the optimum insertion sites and length.Results:The sciatic nerve SN, the obturator nerve ON, the external iliac vessels EIV are respectively located at3-5o’clock,9-10o’clock,9-12o’clock out the margin of acetabulum. The neurovascular distance to acetabular at the left side:SN was11.29±2.13mm, ON was14.69±2.12mm, EIV was17.14± 1.80mm; The neurovascular distance to acetabular at the right side:SN was13.02±2.51mm, ON was15.87±2.14, EIV was17.84±1.95mm. The t test’s p values of SN, ON, EIV of two side are0.454,0.878,0.831, they are greater than0.05. So no statistically significant difference between the left and right of the SN, ON, EIV. Results of points:D1>D2>C2>C1>D0>D3>30mm, the remaining points mean not reached30mm.The respectively screw placement site Dl (57.87±7.27mm), D2(46.05+7.73mm), C2(44.56+8.16mm), C1(42.58+4.77mm), DO (32.10+3.61mm), D3(30.83+2.69mm). D1is different with any site. There are no differences between D2and C2, C1, but other sites. There are no differences between DO and D3, but other sites. no difference,and the rest loci were different.Conclusion:Acetabular prosthesis auxiliary screw optimum point position is D1(57.87±7.27mm), followed by D2(46.05±7.73mm), C2(44.56+8.16mm), C1(42.58+4.77mm), again for the DO (32.1±3.61),(30.82±2.69) D3. So when we choose points in a screw placement the sequence should be D1>D2, C2, C1>D0, D3. The best placement area should be the square area quadrant made up by the D1, D2, C2, C1. The acetabular screw length in this area can be more than40mm.