后内侧入路建立兔膝关节软骨缺损动物模型

Establishment of a rabbit articular cartilage defect model via a posteromedial knee approach

目的 以膝关节后内侧入路手术方法建立兔膝关节软骨缺损动物模型.方法 选择成年12个月龄新西兰大白兔20只,雌雄不限,随机编为5组.组1：进行兔膝关节运动规律研究确定股骨髁主要负重区;组2：无痛处死实验兔后取双膝关节离体标本,解剖观察膝关节周围主要肌肉、神经分布;组3：利用血管造影及三维重建观察兔膝关节周围主要血管分布情况;组4：无痛处死实验兔后取双膝关节离体标本,分别选择髌前内侧入路和膝关节后内侧入路显露股骨髁,比较术野显露差异;组5：活体兔膝关节后内侧入路构建股骨内侧髁软骨缺损.结果 关节负重区中点与股骨髁上中点连线与股骨干轴线夹角平均为90° ～130°,提示兔股骨膝关节主要负重区位于股骨髁后部;后内侧拟行手术切口处主要组织有浅表的股薄肌筋膜,深面有半膜肌、半腱肌,切开股薄肌筋膜及半膜肌于股骨远端止点后于胫侧副韧带、半腱肌、腓肠肌内侧头组成的三角间隙内切开关节囊,即可显露股骨内侧髁后部;膝后主要神经支离手术切口最短距离平均为（0.45 ±0.11） cm,兔膝关节离后内侧切口最近的动脉为膝降动脉,最短距离平均为（0.31 ±0.06） cm;离体标本与活体实验证明后内侧手术切口可很好地显露股骨内侧髁主要负重区软骨.结论 后内侧入路构建兔膝关节内侧股骨髁主要负重区软骨缺损是一种较为理想的动物实验手术方式.

Objective To establish a rabbit knee articular cartilage defect model through a posteromedial knee approach.Methods A total of 20 New Zealand white rabbits of both genders aged 12 months were randomly divided into 5 groups.The habitual weight-bearing area of the femoral condyle was further confirmed by observing the rabbit knee motion characteristics in the first group.For the second group,we were able to describe the distribution of the muscles and nerve fibers that surround the knee joint based on the anatomy of cadaveric specimens.CT scan and angiography of the rabbit knee joints in the third group enabled the clear visualization of the blood vessel distribution.The operative field and exposure were compared between a patellar anteromedial approach and a posteromedial knee approach on fresh isolated rabbit knee specimens obtained from the fourth group.The medial femoral condylar cartilage defects were constructed on live rabbits in the fifth group using a posteromedial knee incision.Results The average angle between the connecting line of the midpoint of the knee weight-bearing region and the femoral condyle ranged from 90° to 130° which suggest that the habitual weight-bearing area of the femoral condyle is located in the caudal half region （posterior aspect）;The main tissues at risk for injury are the gracilis aponeurosis in the outermost layer and the semimembranosus and semitendinous at the bottom of gracilis aponeurosis,which are directly below the posteromedial incision.The posterior portion of the medial femoral condyle may be fully exposed in the knee extension position after partial incision through the triangular space composed of tibial collateral ligament,semitendinosus muscle and the medial head of the gastrocnemius muscle after cut open the gracilis fascia and and the semimembranosus at the distal end of the femur;The average minimum distance from the major nerve branch to the surgical incision was （0.45 ± 0.11） cm;The descending genicular artery is the major artery around the rabbit knee,which is close to the surgical incision,with an average minimum distance from the artery to the incision of （0.31 ± 0.06） cm;This approach may provide excellent exposure for the caudal half of the medial femoral condyle in vitro or in vivo experiments.Conclusion The posteromedial approach is an optimal method for cartilage defect construction on the medial femoral condyle,which merits animal experimentation.