Comparative Study Of New Zealand White Rabbits Disc Degeneration Animal Models

Although an ideal experimental animal model is necessary for the intervertebral disc tissue engineering,currently an accepted experimental animal models prepartion method is lacked, therefore exploring a less invasive, repeatable and simple method of intervertebral disc degeneration animal models prepartion is the priority of the intervertebral disc tissue engineering studys.Compare the advantages and disadvantages of the establishment of the intervertebral disc degeneration animal models by means of C-arm-assisted percutaneous annulus fibrosus puncture, right posterolateral extraperitoneal approach annulus fibrosus puncture and right posterolateral extraperitoneal approach nucleus aspiration through the MRI imaging and biochemistry testing technique; assess the feasibility of the eastblishment of the intervertebral disc degeneration animal model by means of C-arm-assisted percutaneous annulus fibrosus puncture. The study was divided into two parts, the first part was the establishment of the animal models of intervertebral disc degeneration, the second part was the detection and evaluation of the animal modesl of intervertebral disc degeneration.Twenty-seven New Zealand white rabbits of clean grade were selected in this study and distributed into C-arm-assisted percutaneous annulus fibrosus puncture group, right posterolateral extraperitoneal approach annulus fibrosus puncture group and right posterolateral extraperitoneal approach nucleus aspiration group,each group had nine rabbits. Each rabbit's L2/L3,L3/L4 discs were selected as intervention discs and treated with the surgical intervention, the L1/L2, L5/L6 disc were selected as blank controller and had no intervention. Two rabbits were randomly selected to take the magnetic resonance image of lumbar spine before surgery. Two rabbits were randomly selected in each group to take the magnetic resonance image of lumbar spine at 2,4,8,12 weeks respectively after operation, then the animals were killed, nucleus proteoglycan content were measured by means of dimethylmethyleneblue(DMMB) dye spectrophotometry. T2WI magnetic resonance images of intervertebral disc were assessed for degree of degeneration by means of Pfirrmann grading classification method respectively.The results showed:1. The rabbits in the percutaneous annulus fibrosus puncture group had not the complications such as anesthesia accident, wound infection and posterior limb paralysis, and successfully survived to the end of the study; one animal in the right posterolateral extraperitoneal approach puncture group was died of anesthesia accident intraoperatively; wound infection and dehiscence occurred in one animal belong to the right posterolateral extraperitoneal approach nucleus aspiration group ,the wound healed after the change of dressing,re-suture and intramuscular injection of antibiotics.2. The proteoglycan content in the nucleus pulposus and Pfirrmann grading of the lumbar median sagittal T2-weighted magnetic resonance imaging of blank disc remained constantly at each time point after the surgery. Surgical intervention groups showed a gradually increasing trend in the intervertebral disc degeneration; observed signs of disc degeneration appeared at 2 weeks after operation in the nucleus aspiration group and was more serious than the signs in the animal models eastablished by means of the annulus fibrosus puncture methods; the disc degeneration of annulus fibrosus puncture groups appeared 4 weeks after operation. Percutaneous annulus fibrosus puncture group and right posterolateral extraperitoneal approach annulus fibrosus puncture group had a approximately consistent degeneration performance at the same time point after the surgical intervention.Nucleus aspiration can quickly establish animal models of disc degeneration, by contrast the disc degeneration induced by means of the annulus fibrosus puncture method changed slowly. C-arm X-ray assisted percutaneous puncture was a feasible preparation method of intervertebral disc degeneration model and able to replace the traditional surgical method to simulate the biochemical and imagological changes of intervertebral disc degeneration,which had slight surgical trauma and little postoperative complication.