尺骨冠突骨折合并内侧副韧带前束损伤致肘关节后外侧旋转不稳定的生物力学研究

BIOMECHANICAL STUDY ON POSTEROLATERAL ROTATORY INSTABILITY OF ELBOW IN CORONOID PROCESS FRACTURE WITH ANTERIOR BUNDLE INJURY OF MEDIAL COLLATERAL LIGAMENT

目的探讨Ⅰ、Ⅱ型尺骨冠突骨折合并肘关节内侧副韧带前束(anterior bundle of medial collateral ligament,AMCL)损伤是否会造成肘关节后外侧旋转不稳定,为临床Ⅰ、Ⅱ型尺骨冠突骨折合并AMCL损伤的治疗提供理论依据。方法取10个自愿捐献的新鲜成人尸体肘关节标本,男9例,女1例;年龄19～40岁,平均25.1岁;左侧3例,右侧7例。所有标本均排除骨折、关节脱位、骨关节炎、周围韧带及关节囊机械性损伤。于标本近端肱骨中上段三角肌粗隆处截骨,远端在桡腕关节处离断,保留下尺桡关节,制备骨-关节囊韧带标本。采用生物力学测试系统实施100N单轴压缩实验,分别在屈肘90、60和45°测量标本在下列情况下的负荷-位移曲线:①完整肘关节;②Ⅰ型冠突骨折后肘关节;③Ⅰ型冠突骨折合并AMCL损伤后肘关节;④Ⅱ型冠突骨折合并AMCL损伤后的肘关节。结果屈肘90°后方位移最大,故采用屈肘90°数据行统计分析。屈肘90°时,完整肘关节后方位移(2.17±0.42)mm,在4种损伤条件下最小,肘关节后外侧旋转稳定性最好;Ⅰ型冠突骨折后肘关节后方位移(2.20±0.41)mm,Ⅰ型冠突骨折合并AMCL损伤后肘关节后方位移(2.31±0.34)mm,与完整组比较差异均无统计学意义(P>0.05);Ⅱ型冠突骨折合并AMCL损伤后肘关节后方位移(2.65±0.38)mm,与完整组比较差异有统计学意义(P<0.05)。实验过程中未发现肱尺关节或桡骨头脱位。结论单纯Ⅰ型冠突骨折和Ⅰ型冠突骨折合并AMCL损伤对肘关节后外侧旋转稳定性均无明显影响,此类损伤不需行冠突修复重建;但对于AMCL损伤,由于其是首要的抗外翻稳定结构,建议修复或重建AMCL以改善肘关节外翻稳定性。Ⅱ型冠突骨折合并AMCL损伤会影响肘关节后外侧旋转稳定性,建议行冠突及AMCL修复重建以改善肘关节后外侧旋转稳定性及外翻稳定性。

Objective To investigate whether or not posterolateral rotatory instability of the elbow is due to type-Ⅰ and type-Ⅱ coronoid process fracture together with anterior bundle of medial collateral ligament（AMCL）injury so as to provide a theoretic basis for its clinical treatment.Methods Ten fresh-frozen upper extremities were collected from cadavera which was donated voluntarily with no evidence of fracture,dislocation,osteoarthritis,mechanical injury of the surrounding ligament and joint capsule.They included 9 males and 1 female with an average age of 25.1 years（range,19-40 years）,including 3 cases at left sides and 7 cases at right sides.All specimens were transected at the upper midhumeral and carpal levels preserving the distal radioulnar joints to get the bone-ligament specimens.An axial load of 100 N compressing the elbow joint was applied along the shaft of the forearm in the sagittal plane through the biomechanical study system.The load-displacement plot was measured and analyzed at elbow flexion of 90,60,and 45°and under four conditions（intact elbow,type-Ⅰ coronoid process fracture,type-Ⅰ coronoid process fracture with AMCL deficient,and type-Ⅱ coronoid process fractures with AMCL deficient）.Results The posterior displacements were maximum at 90°elbow flexion.Hence,the results at 90°elbow flexion were analyzed：under condition of intact elbows,the posterior displacement was the smallest（2.17±0.42）mm and the posterolateral rotatory stability was the greatest;under condition of type-Ⅰ coronoid process fracture,the posterior displacement was（2.20±0.41）mm,showing no significant difference compared with that of the intact elbow（P0.05）;under condition of type-Ⅰ coronoid process fracture with AMCL deficient,the posterior displacement was（2.31±0.34）mm,showing no significant difference compared with that of intact elbow（P0.05）;and under condition of type-Ⅱ coronoid process fracture with AMCL deficient,the posterior displacement was（2.65±0.38）mm,showing a significant difference compared with that of intact elbow（P0.05）.There was no macroscopic ulnohumeral dislocation or radial head dislocation during the experiment.Conclusion An simple type-Ⅰ coronoid process fracture or with AMCL deficient would not cause posterolateral rotatory instability of elbow and may not need to be repaired.But type-Ⅱ coronoid process fractures with AMCL deficient can cause posterolateral rotatory instability of elbow,so the coronoid process and the AMCL should be repaired or reconstructed to restore posterolateral rotatory stability as well as valgus stability.