Ⅳ型胫骨平台骨折后外侧塌陷关节面固定方式的生物力学研究

Biomechanical analysis of three different fixations for Schatzker type Ⅳ tibial plateau fractures with posterolateral articular depression

目的评估不同固定方式治疗后外侧关节面塌陷的SchatzkerⅣ型胫骨平台骨折的生物力学效果。方法利用人工骨建立SchatzkerⅣ型胫骨平台骨折伴后外侧关节面塌陷的模型18例,将其均分为3组,分别模拟3种内固定方式固定:A组采用内侧钢板固定;B组采用内侧钢板加后侧支撑钢板固定;C组增加外侧骨窗,采用内外侧双钢板固定。通过力学实验机加载静态负荷,获得塌陷关节面与周围相连皮质断裂时以及垂直位移>3 mm时的载荷值。结果塌陷关节面与相连皮质断裂时所加载的负荷为A组(1 715.0±52.1)N、B组(2 631.7±81.8)N、C组(2 763.3±51.6)N,3组间载荷存在差异(F=486.183,P=0.000),3组间两两比较差异均有统计学意义(P均<0.05)。塌陷关节面垂直位移>3 mm时的载荷为A组(2 360.0±71.0)N,B组(3 125.0±104.4)N,C组(3 418.3±81.3)N,3组间载荷存在差异(F=238.140,P=0.000),3组间两两比较差异均有统计学意义(P均<0.05)。结论对于合并后外侧关节面塌陷的SchatzkerⅣ型胫骨平台骨折,增加外侧骨窗、内侧联合外侧钢板固定对于塌陷关节面的固定强度最高,内侧联合后侧钢板固定的强度次之,理论上两者均可承受行走时负荷;单纯内侧钢板固定强度最低,但亦可满足非负重功能锻炼时的负荷要求。

Objective This study aimed to compare the biomechanical characteristics of different fixations for Schatzker type Ⅳtibial plateau fractures with posterolateral articular depression.Methods Eighteen synthetic bones simulated the Schatzker type Ⅳtibial plateau fractures with posterolateral articular depression and then divided into three groups on average.Group A were fixed with a medial plate;in Group B,medial plating combined with posterior plate fixation was applied;and Group C were fixed with medial and lateral plating following creation of a“bone window”on the lateral cortex.Static forces were applied by a testing machine.The load were recorded when the articular surface collapsed and when fragments displaced vertically over 3 mm.Results The load when the articular surface collapsed was 1 715.0±52.1 N in group A,2 631.7±81.8 N in group B and 2 763.3±51.6 N in group C.There was statistically significant difference among the three groups(F=486.183,P=0.000),and between any two groups(P<0.05).The load when the vertical displacement exceeded 3 mm was 2 360.0±71.0 N in group A,3 125.0±104.4 N in group B and 3 418.3±81.3 N in group C.There was statistically significant difference among the three groups(F=238.140,P=0.000),and between any two groups(P<0.05).Conclusion The medial and lateral plating fixation following creation of a“bone window”on the lateral cortex exhibited the best strength in treatment of Schatzker type Ⅳ tibial plateau fractures with posterolateral surface depression.The medial plating combined with posterior buttress fixation was superior to the medial plating alone in terms of resistance of fragment displacement.Both fixation strategies could tolerate the load during walking in theory.The medial plating displayed the lowest biomechanical characteristics,but could allow non-weight-bearing functional exercise.