上中胸椎经椎弓根-肋骨单元途径置钉的安全性及稳定性研究

Study on the safety and stability of upper-middle thoracic pedicle screw insertion through pedicle rib unit approach

目的:探讨上中胸椎经椎弓根-肋骨单元(pedicle rib unit,PRU)途径置钉的安全性及稳定性。方法:对10名无脊柱病变的志愿者进行脊柱T_1~T_8。节段CT扫描,在获得的CT图像上测定各节段的PRU途径置钉安全角度范围、椎弓根横径、PRU横径、椎弓根纵径、PRU纵径及PRU重叠纵径。取4具尸体脊柱标本(T_1~T_8节段),对应肋骨保留10 cm左右。随机于每个脊柱标本的两侧分别经经典椎弓根途径和PRU途径置入椎弓根螺钉,两侧螺钉的直径及长度分别为对应的椎弓根横径的70%和各自钉道最长值的70%。应用Instron 5569电子万能试验机测定螺钉的抗拔出力。结果:10名志愿者T_1~T_8途经PRU途径置钉的安全角度范围分别为19.71°±1.64°、19.42°±1.88°、17.17°±0.67°、17.22°±1.170、19.36°±1.31°、18.67°±1.58°、18.82°±2.60°、18.72°±1.58°。10名志愿者T_1~T_8椎弓根横径均小于同节段的PRU横径[(8.78±0.05)mm,(18.23±2.46)mm,t=18.192,P=0.013;(7.59±0.08)mm,(16.80±1.31)mm,t=20.175,P=0.002;(6.29±0.07)mm,(15.12±1.22)mm,t=20.271,P=0.004;(5.50±0.05)mm,(14.43±1.00)mm,t=27.403,P=0.004;(5.52±0.06)mm,(14.02±0.85)mm,t=20.312,P=0.001;(5.90±0.06)mm,(14.19±1.12)mm,t=16.772,P=0.047;(6.31±0.07)mm,(14.77±1.31)mm,t=14.229,P=0.017;(6.64±0.03)mm,(15.53±1.90)mm,t=13.000,P=0.048)。10名志愿者T_1~T_8椎弓根纵径、PRU纵径、PRU重叠纵径三者之间总体比较差异均有统计学意义[(8.04±1.01)mm,(11.05±1.83)mm,(6.37±0.68)mm,F=236.422,P=0.000;(10.72±0.99)mm,(13.09±1.30)mm,(7.46±1.12)mm,F=60.570,P=0.000;(11.34±0.99)mm,(13.45±0.92)mm,(8.99±0.62)mm,F=67.560,P=0.000;(10.67±0.91)mm,(12.49±0.94)mm,(7.94±0.84)mm,F=64.965,P=0.000;(10.34±0.94)mm,(11.96±0.95)mm,(7.96±0.96)mm,F=44.926,P=0.000;(11.33±0.96)mm,(12.36±0.62)mm,(7.72±0.88)mm,F=85.197,P=0.000;(11.30±0.82)mm,(12.16±0.71)mm,(8.34±0.47)mm,F=92.350,P=0.000;(11.39±0.78)mm,(13.71±1.51)mm,(9.34±0.93)mm,F=37.867,P=0.000)。T_1~T_8椎弓根纵径和PRU纵径均大于PRU重叠纵径(P=0.004,P=0.003,P=0.001,P=0.002,P=0.013,P=0.030,P=0.025,P=0.001;P=0.000,P=0.000,P=0.000,P=0.000,P=0.000,P=0.000,P=0.000,P=0.000),椎弓根纵径均小于PRU纵径(P=0.000,P=0.000,P=0.000,P=0.000,P=0.000,P=0.000,P=0.000,P=0.000)。T_1~T_8各节段经椎弓根途径置入螺钉的抗拔出力均大于经PRU途径[(663.60±22.13)N,(470.33±33.09)N,t=27.876,P=0.000;(702.82±24.23)N,(531.76±13.53)N,t=38.402,P=0.000;(713.58±37.90)N,(544.98±14.22)N,t=37.518,P=0.000;(700.70±35.66)N,(590.80±24.72)N,t=10.512,P=0.000;(805.28±64.67)N,(591.50±62.55)N,t=19.546,P=0.000;(808.68±42.84)N,(629.08±43.09)N,t=19.436,P=0.000;(864.62±35.49)N,(591.60±52.91)N,t=24.350,P=0.000;(909.18±46.05)N,(640.70±21.41)N,t=15.162,P=0.000]。结论:上中胸椎经PRU途径置入椎弓根螺钉的安全性优于经椎弓根途径,但置入螺钉的稳定性不及后者。

Objective：To explore the safety and stability of upper- middle thoracic pedicle screw insertion through pedicle rib unit（PRU） approach.Methods：Ten volunteers with no spinal disease received CT scanning at T1-8 vertebral segments,and safe angle range of pedicle screw insertion through PRU approach,transverse diameter of pedicle of vertebral arch,transverse diameter of PRU,longitudinal diameter of pedicle of vertebral arch,longitudinal diameter of PRU and PRU overlapped longitudinal diameter of all segments were measured on the obtained CT images.Four cadaveric T_（1-8） specimens were selected and 10 cm long ribs were reserved.The pedicle screws were randomly inserted into both sides of each spine specimen through classical pedicle of vertebral arch approach and PRU approach respectively.The diameters of the screws were 70%of transverse diameter of corresponding pedicles of vertebral arch and the lengths of the screws were70%of the maximal values of corresponding screw path lengths.The pullout strength of the screws were measured by using instron 5569 electronic universal testing machine.Results：The safe angle ranges of pedicle screw insertion through PRU approach were 19.71 ＋/- 1.64,19.42 ＋/-1.88,17.17 ＋/-0.67,17.22 ＋/-1.17,19.36 ＋/-1.31,18.67 ＋/-1.58,18.82 ＋/-2.60,18.72 ＋/-1.58 degrees respectively at T1- 8 vertebral segments of 10 volunteers.The transverse diameters of pedicle of vertebral arch were less than the transverse diameter of PRU at T_（1-8） vertebral segments of the 10 volunteers（8.78 ＋/-0.05 vs 18.23 ＋/-2.46 mm;t=18.192,P = 0.013;7.59 ＋/-0.08 vs16.80 ＋/-1.31 mm,t=20.175,P =0.002;6.29＋/-0.07 vs 15.12 ＋/-1.22 mm,t=20.271,P =0.004;5.50＋/-0.05 vs 14.43 ＋/-1.00 mm,t=21.403,P=0.004;5.52 ＋/-0.06 vs 14.02 ＋/-0.85 mm,t=20.312,P = 0.001;5.90 ＋/-0.06 vs 14.19 ＋/-1.12 mm,t=16.112,P=0.041;6.31 ＋/-0.07 vs 14.77＋/-1.31 mm,t =14.229 P =0.017;6.64 ＋/-0.03 vs 15.53＋/-1.90 mm,t= 13.000,P =0.048）.In general,there was statistical difference between longitudinal diameter of pedicle of vertebral arch,longitudinal diameter of PRU and PRU overlapped longitudinal diameter at T_（1-8） vertebral segments of the 10 volunteers（8.04 ＋/- 1.01,11.05 ＋/- 1.83 6.37 ＋/-0.68 mm,F =236.422,P = 0.000;10.72 ＋/-0.99,13.09 ＋/-1.30,7.46 ＋/-1.12 mm,F = 60.570,P = 0.000;11.34 ＋/-0.99,13.45 ＋/- 0.92,8- 99 ＋/- 0.62 mm,F = 67.560,P =0.000;10.67 ＋/- 0.91,12.49 ＋/- 0.94,7.94 ＋/- 0.84 mm,F = 64.965,P =0.000;10.34 ＋/-0.94,11.96 ＋/- 0.95,7.96 ＋/- 0.96 mm,F = 44.926,P = 0.000;11.33 ＋/- 0.96,12.36 ＋/- 0.62,7.72 ＋/-0.88 mm,F= 85.197,P =0.000;11.30 ＋/-0.82,12.16 ＋/-0.71,8.34 ＋/-0.47 mm,F = 92.350,P =0.000;11.39 ＋/-0.78,13.71 ＋/-1.51 9.34 ＋/-0.93 mm,F = 37.867,P=0.000）.The longitudinal diameter of pedicle of vertebral arch and the longitudinal diameter of PRU were larger than PRU overlapped longitudinal diameter of the 10 volunteers at Tl- 8 vertebral segments（P = 0.004 P =0.003,P=0.001 P=0.002,P= 0.013,P=0.030,P=0.025,P = 0.001;P =0.000,P=0.000,P=0.000,P=0.000,P=0.000 P=0.000,P = 0.000,P = 0.000）,and the longitudinal diameter of pedicle of vertebral arch was less than longitudinal diameter of PRU（P =0.000,P = 0.000,P = 0.000 P=0.000 P= 0.000 P = 0.000,P = 0.000,P=0.000）.The pull- out strengths of the screws inserted through the pedicle of vertebral arch approach were greater than those through PRU approach at T_（1-8） vertebral segments（663.60 ＋/-22,13 vs 470.33＋/-33.09 N,t=27.876,P = 0.000;702.82 ＋/-24.23 vs 531.76＋/-13.53 N,t= 38.402,P =0.000;713.58 ＋/-37.90 vs544.98＋/-14.22 N,t =37.518,P =0.000;700.70 ＋/- 35.66 vs 590.80＋/-24.72 N,t = 10.512,P = 0.000;805.28 ＋/-64.67 vs591.50＋/-62.55 N,t = 19.546,P =0.000;808.68 ＋/-42.84 vs 629.08 ＋/-43.09 N,t = 19.436,P = 0.000;864.62 ＋/-35.49 vs591.60＋/-52.91 N,t=24.350 P =0.000;909.18 ＋/-46.05 vs 640.70＋/-21.41 N,t= 15.162,P = 0.000）.Conclusion：PRU approach surpasses pedicle of vertebral arch approach in the safety of upper- middle thoracic pedicle screw insertion.however,the latter surpasses the former in the stability of inserted screws.