胫骨外侧髁骨折塌陷对关节轴线及接触压力的影响

The effect of articular step-off and neniscectomy on joint alignment and contact pressures for fractures of the lateral tibial plateau

目的:研究在胫骨外侧髁骨折中关节面塌陷和外侧半月板切除对膝关节轴线、接触面积及压力的影响。方法:6个新鲜尸体膝关节标本制成胫骨外侧髁劈裂骨折模型,通过使用支撑垫片制成关节面塌陷0、1、2、4和6mm。膝关节在屈膝0°,负荷500N和屈膝30°,负荷350N。通过数码相机记录关节轴线的变化;而关节内外间隙的压力和压力扩散则由F-Scan感应器记录。每个标本在保留和切除外侧半月板下进行测试。结果:随着关节面塌陷高度的增加,膝关节外翻角度、外侧间隙的平均和最大的接触压力逐渐增加,而接触面积则逐渐减少。在屈膝0°,关节面塌陷6mm时,外翻角度平均增加7.6°,平均接触压力和最大接触压力分别增加208%和97%;而接触面积则减少33%。在同一关节面塌陷高度,切除半月板平均增加38%的外翻角度和外侧间隙45%的接触压力;而接触面积则减少26%。结论:研究结果表明在治疗胫骨外髁劈裂骨折中,减少关节面的塌陷十分重要,特别是在需切除半月板的时候。

Objectives: This study was performed to determine the effects of intra-articular step-off and lateral meniscectomy on the alignment of the articular axis, contact area and pressures for lateral tibial plateau fractures. Methods: Six fresh cadaveric knees were used. A simulated split fracture of the lateral tibial plateau was reproducibly created by osteotomies, and articular step-offs of 0, 1, 2, 4, and 6 mm were achieved by using support shims. The knee was loaded with 500N in 00 and 350N in 300 of flexion. A digital camera determined changes in the alignment of the articular axis, and F-Scan sensors were inserted into the medial and lateral joint compartments to determine the pressures and pressure distributions. Each specimen was tested with the presence or absence of the lateral meniscus. Results: Increased articular step-off heights progressively increased valgus angle, and average and maximum contact pressures, and progressively decreased contact areas in lateral compartment. At a 6 mm step-off with 00 of flexion, the valgus angle increased an average of 7.60, and average contact pressures and maximum contact pressures increased an average of 208% and 97% respectively, and contact area decreased an average 33%. Meniscectomy increased valgus angles by an average of 38% and contact pressures by an average of 45% and decreased contact areas by 26% in the lateral compartment at the same articular step-off heights. Conclusions: The results of this study demonstrate the importance of decreasing articular step-off heights in treating lateral tibial plateau split fractures, particularly if a meniscectomy is performed.