术后早期活动对同种异体关节移植后关节软骨保护作用的实验研究

目的采用同种异体关节移植动物模型,于术后采用不同处理方法进行对照实验,探讨同种异体关节移植后早期活动对关节软骨的保护作用。方法选用生长条件相同的6月龄新西兰大耳白兔10只(雌雄不限,体重2.5～3.0 kg)作为供体,取其一侧半膝关节,经深低温冻存处理后移植于取下股骨侧半膝关节的6月龄青紫蓝兔(雌雄不限,体重2.5～3.0 kg)膝关节处,术后分别给予早期活动(术后2周,早期活动组,n=5)或持续石膏固定6周(持续固定组,n=5);并取供体对侧半膝关节设立空白对照组(未经任何处理,n=5)和冻存对照组(经深低温处理2周,n=5)。术后分别行大体、X线片及组织学观测,观察同种异体关节软骨的变化情况。结果大体观察示,早期活动组实验兔关节活动良好;持续固定组实验兔关节活动受限明显。X线片示,术后当天、术后2周同种异体关节供体骨端与受体骨端对合整齐、对位对线良好;术后6周,早期活动组3只实验兔受体和供体骨端略有成角畸形,持续固定组对位及对线仍良好。HE染色示,早期活动组同种异体半膝关节标本软骨细胞数量和形态基本正常,偶见核碎裂及核溶解;持续固定组同种异体半膝关节标本中软骨细胞大量减少,大部分细胞核溶解消失,软骨基质中大量纤维组织增生。细胞存活率检测示,早期活动组细胞存活率(49.66%±2.15%)显著高于持续固定组(20.68%±1.24%),比较差异有统计学意义(P<0.05)。扫描电镜观察示,早期活动组同种异体半膝关节标本可见软骨细胞细胞核核膜尚完整,染色质凝聚、边集,线粒体及粗面内质网肿胀;持续固定组同种异体半膝关节标本可见软骨细胞细胞膜消失,软骨细胞与周围基质界限不清,核膜破裂,染色质及细胞质内细胞器消失。结论同种异体关节移植术后进行早期功能活动对兔关节软骨有保护作用,但不能完全阻止软骨退变。

Experimental study on protective effect of early motion on articular cartilage after joint allograft

Objective To investigate the protective effect of early motion on articular cartilage after joint allograft by performing a controlled trial between different post-operation strategies after joint allograft in an animal model.Methods Twenty hemi-knee joints were harvested from 10 6-month-old New Zealand white rabbits(male or female,weighing 2.5-3.0 kg);10 hemi-knee joints by deep frozen treatment(donors) were transplanted to unilateral knee joints(recipients) of 10 6-month-old Chinchilla rabbits(male or female,weighing 2.5-3.0 kg),which were divided into early motion group(n=5) and sustained fixation group(n=5);and 10 hemi-knee joints were used as blank control(n=5) and frozen control(n=5).The articular cartilage of allogenic joints was detected by X-ray film,gross,and histology at 6 weeks after operation.Results Gross observation: no obvious limitation of joint movements was observed in early motion group,but obvious limitation in sustained fixation group.X-ray films: the bone ends between donor and recipient healed well with good paraposition and alignment on the operation day and 2 weeks after operation;at 6 weeks,angulation deformity was observed in early motion group of 3 rabbits,and paraposition and alignment were satisfactory in sustained fixation group.Histological observation: HE staining showed that the chondrocytes had normal quantity and morphology with few nuclear fragmentation and karyolysis in early motion group,but the quantity of chondrocytes sharply decreased with dissolved nuclei and numerous fibrous tissues in the cartilage matrix in sustained fixation group.The cell survival rate of the early motion group(49.66% ± 2.15%) was significantly higher than that of the sustained fixation group(20.68% ± 1.24%)(P < 0.05).Scanning electron microscopy observation: nuclear membrane was intact with chromatin condensation and edema of mitochondria and rough surfaced endoplasmic reticulum in early motion group,and that the membrane of chondrocyte vanished with blurring border between chondrocyte and matrix,rupture of nuclear membrane and the disappearance of chromatin and organelles could be found in sustained fixation group.Conclusion Early motion has protective effect on articular cartilage after joint allograft,but cannot completely prevent degeneration of the allogenic articular cartilage.