骰骨跨关节接骨板的设计与生物力学研究

DESIGN AND BIOMECHANICAL STUDY OF TRANSARTICULAR CUBOID BONE PLATE

目的通过测量及收集骰骨前后关节面的解剖学数据,设计用于复杂骰骨骨折的跨关节接骨板螺钉系统。采用生物力学试验对设计的骰骨跨关节接骨板进行力学分析。方法根据在100例成人足部内斜位X线片上及30具成人足部标本上测得的骰骨-第5跖骨关节面与第5跖骨干纵轴夹角α及骰骨-第5跖骨关节面与跟骰关节面延长线夹角β,结合已有文献数据,设计用于成人骰骨骨折的跨关节内固定接骨板,α、β角分别设计为70°和30°。取6具成人足部标本,距踝关节近端15 cm处截骨后,在跟、骰及第4、5跖骨处放置a^e 5枚电阻应变片,加载至600 N后测量各个点的应变值;然后制作骰骨骨折模型,同上法测量各个点的应变值并与骨折前比较;将标本随机分为两组(n=3),A组采用设计的骰骨跨关节接骨板及9枚螺钉固定骨折,B组采用掌指骨接骨板及8枚螺钉跨关节固定,再次对标本加载600 N压力后记录各个点的应变值及骨折块垂直位移。结果骰骨骨折前后比较,a、d、e点的应变值差异无统计学意义(P>0.05),而b、c点骰骨骨折后应变值明显大于骨折前(P<0.05)。骨折固定后,A、B组加载压力600 N时的各个点应变值比较差异均无统计学意义(P>0.05)。观察实验数据可以得出,相同载荷下,应变值变化主要集中在骨折线处,因此将骨折固定后的b、c两点应变值与骨折前比较,差异均无统计学意义(P>0.05)。骨折固定后A、B组加载压力600 N时的骨折线内侧骨块Y1垂直位移分别为(0.804±0.011)、(1.126±0.083)mm,骨折线外侧骨块Y2垂直位移分别为(0.672±0.036)、(1.007±1.103)mm,A组均显著小于B组,差异有统计学意义(t=—6.711,P=0.003;t=—5.307,P=0.006)。结论设计的新型骰骨跨关节接骨板对骰骨骨折具有更稳定的固定效果。

Objective To design a new type of transarticular cuboid bone plate by measuring and collecting the anatomic data of the articular surface around cuboid, and to carry out comparative biomechanical study. Methods The angle a （between the fifth metatarsocuboid joint and the fifth metatarsal bone） and the angle 13 （between the fifth metatarsocuboid joint and the calcaneocuboid joint） were measured in 100 adults on medial oblique X-ray film and 30 adult foot specimens. Based on literature data, the transarticular cuboid bone plate was designed with an angle a of 70~ and an angle 13 of 30~. Six adult cadaver feet were chosen and were transected approximately 15 cm proximal to the ankle. Five strain gauges were placed at the calcaneus, cuboid, and the fourth and fifth metatarsal bones. The vertical pressure was loaded on the foot at 0-600 N, the strain value was measured. Then the cuboid fracture model was established and 600 N load was given on foot to measure the strain value and compare with the strain value before fracture. The specimens were randomly divided into groups A and B （n=3）. Fracture was fixed with transarticular cuboid bone plate and 9 screws in group A and with double plate and 8 screws in group B, then the 600 N load was given to measure the strain value and vertical displacement of the fracture fragments. Results After loads of 0-600 N on the foot, the strain value of the 5 points showed an increased trend. No significant difference was found in the strain value between pre- and post-fracture at a, d, and e points （P〉0.05）, but it was significantly larger at post-fracture than pre-fracture at b and c points （P〈0.05）. After fracture fixation, no significant difference was shown in the strain value at 5 points between groups A and B when loads of 0-600 N was given （P〉0.05）. The experimental data showed that the strain value change mainly focused on the fracture site under the same load, so the strain value after fracture ftxation was similar to that before fracture at b and c points （P〉0.05）. The vertical displacement values of medial and lateral fracture fragments in group A [（0.804±0.011） mm and （0.672±0.036） ram] were significantly less than those in group B [（1.126±0.083） mm and （1.007±1.103） mm] （t= -6.711, P=0.003; t= -5.307, P=0.006）. Conclusion Through biomechanical study, a new type of transarticular cuboid bone plate has better fixation effect.