三种固定方式治疗肱骨大结节骨折的生物力学研究

Biomechanical research of three fixation methods for treatment of greater tuberosity fractures of humerus

目的比较可吸收缝线(AS)、双螺钉(TS)及双股锚钉(DS)三种固定方式治疗肱骨大结节骨折的生物力学稳定性。方法取新鲜冰冻肩关节标本9对,去除皮肤、肌肉、韧带、肩胛骨、锁骨,保留冈上肌、肱骨干20 cm,以薄刀片的往复锯与肱骨轴底部成50°切割,制作肱骨大结节骨折模型。根据固定方式不同随机分为三组:(1)AS固定组;(2)TS固定组;(3)DS固定组。每组标本均牵拉冈上肌,模拟肩关节0°外展动作,在材料试验机上分别测量骨折块刚发生屈服、位移3 mm、5 mm三种状态时承受的拉力,比较各组间的差异。结果骨折块刚发生屈服、位移3 mm、5 mm时三种固定方式所受拉力均数分别为:(1)AS组:(287.78±20.22)N、(348.67±12.62)N、(374.69±13.68)N;(2)TS组:(146.03±13.73)N、(206.67±23.74)N、(250.42±22.27)N;(3)DS组:(256.26±5.21)N、(337.59±6.18)N、(367.92±9.67)N。三种状态下,TS组拉力值均小于AS组和DS组,差异具有统计学意义(P<0.01);DS与AS两组间差异无统计学意义(P>0.05)。结论可吸收线固定肱骨大结节骨折的生物力学稳定效果与锚钉固定相当,两者均明显优于双螺钉固定,可吸收线缝合固定能有效恢复肱骨大结节骨折的力学稳定性。

Objective To compare the biomechanical strength of three different fixation methods in the management of greater tuberosity ( GT) fractures: double suture anchor fixation, absorbable suture fixation, and two-screw fixation.Methods Nine pairs of fresh-frozen shoulder specimens of human cadavers were used.The skin, subcutaneous tissue, muscles, ligaments, tendons, scapula, and clavicles were resected, retaining only the humerus and supraspinatus.The distal humeral condyle was removed, leaving a 20 cm long humeral shaft.Standardized osteotomy oriented 50°to the humeral shaft was performed at the base of the GT using a thin blade reciprocating saw.The fracture samples were randomly assigned to three groups of three fixation methods:the AS group ( absorbable suture fixation) , the TS group ( two-screw fixation) and the DS group ( double suture anchor fixation) , six specimens in each group.The specimens simulated 0°abduction of the shoulder joint.The loading forces of the three fixation methods were determined at the yield and at the displacements of 3 mm and 5 mm.Results The mean loading force at the yield, at the displacement of 3 mm and the displacement of 5 mm in the AS group were as follows:(287.78 ±20.22) N, (348.67 ±12.62) N, (374.69 ±13.68) N; the data in the TS group were (146.03 ±13.73) N, ( 206.67 ±23.74 ) N, ( 250.42 ±22.27 ) N; the data in the DS group were (256.26 ±5.21 ) N, ( 337.59 ±6.18 ) N, ( 367.92 ±9.67 ) N.There were significant differences between the DS and TS groups as well as the AS and TS groups (P<0.01).No significant difference was found between the DS and AS groups ( P>0.05 ) .Conclusions The results suggest that the absorbable suture fixation and suture anchor fixation may be stronger than the fixation using screws in the treatment of the humeral GT fracture.Absorbable suture fixation can effectively restore the mechanical stability of the fractures of greater tuberosity of humerus.