兔运动对骨软骨骨折转归的影响:MRI表现与MMP-13表达

Influence of movement on outcome of osteochondral fracture in rabbits:MRI features and MMP-13 expressions

目的:观察实验兔运动对骨软骨骨折转归影响及骨片覆盖软骨MMP-13表达,探讨骨软骨骨折与剥脱性骨软骨炎的关系。方法:随机选用30只月龄及体重相近的健康新西兰大白兔,雌雄不限;试验组20只建立兔膝股骨髁骨软骨骨折模型,假手术对照组10只,所有模型均不进行内固定及外固定。术后即进行术侧膝关节间歇主动活动(IAM)与间歇被动活动(IPM);术后1、2周分别从试验组中随机抽取10只实验兔行MRI检查、大体观察、组织学检查,假手术对照组10只于术后2周行上述检查。MRI扫描序列包括TSE-T1WI、TSE-T2WI、T2WI/SPAIR、3D/WATSc/FFE/T1WI。结果:术后1、2周,骨折线均清晰,骨软骨骨折片移位14(14/20);骨片覆盖软骨术后2周较术后1周损伤重(P<0.05);骨折区成纤维细胞数术后2周较术后1周多(P<0.05)。术后第2周,股骨髁骨折处骨质增生,MRI示薄层低信号,骨片内部分骨小梁坏死;骨片覆盖软骨MMP-13表达,术后2周较术后1周表达程度明显增高(P<0.05),对照组仅2(2/10)只轻度表达。结论:运动可使兔股骨髁骨软骨骨折愈合不佳,术后2周变化类似剥脱性骨软骨炎的特点;骨软骨骨折后骨片覆盖软骨MMP-13表达升高,对临床治疗骨软骨骨折及评价预后具有重要意义。

Objective：To observe the influence of movement on outcome of osteochondral fracture and the expression of MMP-13 in the covering cartilage of bone flap and to explore the relationship between the osteochondral fracture and the osteochondritis dissecans.Methods：Thirty Newzealand rabbits were chosen randomly,whose weight was close to each other,and whose gender was not restricted.We made osteochondral fracture models of 20 rabbits,another 10 rabbits received unilateral knee arthrotomy as pseudoperation controls.All models were not treated by internal or external fixation.Then,the knee on the model side was enforced to do intermittent passive and active movement.Ten experimental rabbits were chosen after one week and two weeks respectively and randomly and received MRI examination,pathological observation and histological examination respectively.MRI sequences included TSE-T1WI、TSE-T2WI、T2WI/SPAIR、3D/WATSc/FFE/T1WI.Results：In one and two weeks points after damaging,the fracture lines were clear and osteochondral fragment displaced in 14 cases （14/20）.In two weeks point,the obducent cartilage of bone fragment was worse than that in one week （P〈0.05）.In two weeks point,the number of fibroblasts in fracture zone was greater than that in one week point （P〈0.05）.In two weeks point,the fracture of the femoral condyles presented obvious hyperosteogeny,MR images showed lamellar low signals,and part of bone trabeculae in bone fragment showed necrosis.The control group had no changs.The covering cartilage of bone flap expression of MMP-13 was higher two week later than one week later,while in the control group there was only slight expression in 2 rabbits （2/10）.Conclusion：The influence of movement on osteochondral fracture is obvious which brings the fracture healing below normal standard.MRI features and pathological changes of osteochondral fracture were similar to osteochondritis dissecans in two weeks point.The increase of MMP-13 expression of the covering cartilage of bone flap is of significance for clinical therapy.