| Objective:Femoral head avascular or oschemic necrosis (ANFH) is a commonorthopaedic disease, also the hotspot and difficulty of clinical orthopedicexperimental research. ANFH is more prevalent from thirty to fifty years old,and its pathogenesis is complex, mainly due to trauma, application hormone,excessive drinking, connective tissue disease and so on, which result in thelocal nourishing blood vessel of femoral head damaged, leading to thepathological changes of the organization of the femoral head, causing acorresponding clinical manifestations. If the patient didn’t have timely andeffective treatments, he had to make a artificial joints replacement finally.Various reasons result in osteonecrosis, it will affect the blood supplying offemoral head area at first, and lead to femoral head area insufficient bloodsupplying, resulting in avascular necrosis of the corresponding areas. In ourexperiment, we blocked the blood supply of the femoral head area by usingthe method of femoral head ligament ligation, to observe the morphologicalchanges of femoral head before and after blocking, to investigate the relationbetween the blood supply of femoral head ligaments and the femoral headavascular necrosis.Methods:1Animals grouping and model preparationSixteen New Zealand rabbits, five-months-old, weighing2.0to2.5kg,male and female unlimited, were housed in single cage, with free access tofood and water, adaptive feed for a week. The animals were randomly dividedinto operated group(12rabbits) and sham operated group (4rabbits).1.1Operated group the rabbits were fixed in operating table, injecting10%chloral hydrate(2.4ml/kg) to anesthesia through ear marginal vein, and the right side of thehip joint have an operation, the left as a control. Make a vertical incision in thelower abdomen midline next to1cm,2~3cm length, open the skin step bystep, fascia layer, throgh muscle clearance, open the hip joint capsule, putthe femoral rotation outside, find the femoral head ligament and ligate it, andmakes the hip joint to reset, close and suture the joint capsule, suture musclelayer, fascia and skin layer by layer.1.2Operation control groupjust open the joint capsule, and find femoral head ligament withouthaving a ligation, do not cause femoral head dislocation. We close and stitchthe joint capsule directly, like the ligation group, to suture layer by layer.bothgroups have a surgery on the right side, as normal controls on the left side.Four rabbits in operated group were sacrificed at4,8,12weeks respectively,one rabbit in the sham operated group was sacrificed corresponding.Removethe bilateral femoral head, put the tissue in the formaldehyde fixative to fix,which are observed by using the light microscope and scanning electronmicroscope.2Light microscope sample preparation and observationThe samples were paraffin-embedded and sliced after appropriatetreatment of femoral head tissue of the two groups., then observe thedifferences of the two groups by HE staining and immunohistochemistry.3Sample preparation and observation of the scanning electron microscopy.Select normal and operated group femoral head specimens, after thetissue fixation with mixed aldehyde fixative, through conventional conductivetreatment, fixation, dehydration, dried in vacuum,fixed to on SEM samplesTorr, observe the structure of the articular surface of the femoral head featureusing the scanning electron microscope.Results:1The state of postoperative observationOne week after operation, the experimental animals had slight claudication in the surgery side, and their activities decreased, poor mentalstate, poor appetite.. A week later, the wound healed well, activities increased,and the hair is bright and clean. Two weeks later, the animal recovered to thepreoperative status, basic wound healing, the wound suture falls off entirely,primary healing.2General observation of the two specimens of femoral headA week after the surgery,the femoral head of operated group are roundand smooth overall, the surface of articular cartilage is normal. The specimensafter surgery in a month, the shape of femoral head are round, articularcartilage surface is slightly pale in a specimens surrounding the ligament.After two months, the articular cartilage surface of the femoral head aroundthe round ligament is mild exfoliation, slightly not smooth. There is a slightcollapse. The articular surface of the control group, a week after thesurgery,looks like normal;the articular surface in a month looks slightly pale,articular surface is smooth as normal. Two months later, the articular surface isround substantially3Observerd by light microscop3.1HE staining of tissue sectionscartilage membrane is normal in the control group, in the subchondralarea rich in blood vessels, cartilage cell growth normally. Trabeculars areplentiful, rules, osteocytes are abundant,empty bone lacunae are less, emptylacunae was17.7%, at the edge of the trabeculars you can see the normalosteoblasts, the number of marrow hematopoietic cells in cancellous bone isnumerous, the number of fat cells is less. While in the model group theperichondrium loss, subchondral vascular almost all have be lost. Bonetrabecular is elongated, irregular, or even broken. The rate of empty bonelacunae increases to35.2%, the number of marrow hematopoietic cells incancellous bone decreased full vision are fat cells (foam cells).3.2The immunohistochemical staining slicesAfter the femoral head ligament are ligated, under the femoral headcartilage, bone morphogenetic protein express slightly increased on the hypertrophic chondrocytes at thebottom of cartilage layer in the operatedgroup compare with normal group, at the same time the expression of theBMP around the bone lacunae and the cartilage is expressive.4Observerd by scanning electron microscopyThe observation of the articular cartilage surface of the femoral head, byusing the scanning electron microscopy,at the area of around the ligament,cartilage surface of the control group, we can see the smooth surface, moreregular. Arounding femoral head ligament of the operated group,there hasbeen a phenomenon in the surface of the articular surface of the femoral headcartilage that the multiple layers of epithelial cells modify, shedding, andrevealed the bottom of the fibrous tissue.Conclusion:1The pathological changes of femoral head osteonecrosis can be observedafter ligation of rabbit femoral head ligament.2The pathological changes were observed under electron microscope: thecartilage layer cells reduced and lost, the collagen fibers under epitheliumbare after ligation of rabbit femoral head ligament.3The femoral head ischemic necrosis rabbit model can be successfuly madeby the ligation of rabbit femoral head ligament method. |
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