Experimental Study On Effect Of Patella Infra On Patellofemoral Joint

Objective: In clinical practice, we can often see the phenomenon according to the causes of patellar Baja, divided into three categories, respectively is the congenital patella baja, acquired patella baja, mixed patella baja. Congenital patella baja refers to patients had disease phenomenon of patella femoral trochlea far distance shortly after birth, which may be caused by genetic problems, or children before birth dysplasia good. Causes of acquired patella baja in many aspects, in clinical common operation, such as after repair of patellar fracture, patellar ligament incision fixation, TKA after operation, especially in recent years, the TKA operation can be increased, induce the formation of patellar Baja, its typical features are far from the femoral trochlea and the patella patellar ligament atrophy. Acquired patella baja change of patellofemoral joint, in clinical in many patients with knee joint pain, weakness, delay, extensor activity limitation, although more common for patients with patella baja, bring a lot of inconvenience, but the phenomenon has not aroused widespread concern of scholars, in the medical profession on the patella baja diseases caused by cognitive is not deep enough, the phenomenon of the disease causes and mechanisms of disease induced illness is still in the exploratory stage, this paper through the experimental animal model of patella baja, this study focuses on the patellofemoral joint pressure in the aspects of change and to find the relationship between the patellofemoral joint cartilage, change of knee joint.Method: choose 40 New Zealand white rabbits, age was 60 days, provided by the animal experimental center of Hebei Medical University, preoperative knee lateral radiographs, patella and patellar ligament length length measurement, calculation of the ratio of patellar ligament and patella length. Divided into control group, A, B, C, D five groups randomly, group A as the left knee into sham operation group, the right knee for the control group, the experimental group B, C, D respectively for three different patella infra model, in the same conditions of cage feeding place an order, the same breeding environment, drinking water, the feed by Hebei Medical Center for animal. In animal experiment, 25% rabbits anesthetized with urethane, each rabbit intravenously injected with 2ml of anesthesia operation, group A rabbits knee to skin incision operation, make the patellar tendon exposed, the patellar tendon with both sides support cut and suture, suture the skin incision, sham operation group(A), group A as control right knee joint. B group of left knee incision skin revealed patellar tendon patellar tendon on both sides, will support with cut and suture, the patellar tendon with check point from tibial bone block scuttling, will stop point down 2mm, using steel wire are fixed, as experimental group B. Experimental group C operation process with the B group, only the patellar tendon down 4mm. Experimental group D operation process is the same as the B, C group, the patellar tendon down after 6mm, using steel wire are fixed. After the patella infra model the New Zealand white rabbits were prepared for making good, still using the single cage feeding mode. Three months after operation, were killed by air embolism method rabbit vein, in four on the femoral muscle with 200 cows of axial tensile force. With the pressure sensor respectively to measure the bending of the knee in 30 degrees, 60 degrees.Results: the patella inside, outside pressureControl group: the lateral pressure in the bending curvature of 30 degrees, 60 degrees,90 degrees were2+0.03, 2.08+0.03, 1.79+0.01; inner pressure in the bending of 30 degrees, 60 degrees, 90 degrees were 1.68+0.12, 2+0.02, 1.31+0.01.Experimental group A: lateral pressure in the bending curvature of 30 degrees, 60 degrees, 90 degrees were 2.01+0.04, 2.09+0.04, 1.80+0.02; inner pressure in the bending of 30 degrees, 60 degrees, 90 degrees were 1.69+0.12, 2.01+0.03, 1.32+0.03.Experimental group B: the lateral patellofemoral pressure in the bending curvature of 30 degrees, 60 degrees, 90 degrees is 2.09+0.02, corresponding to 2.20+0.05, 1.70+0.05; the pressure in the bending of 30 degrees, 60 degrees, 90 degrees were 2.06+0.03, 2.14+0.04, 1.18+0.06.Experimental group C: lateral pressure in the bending of 30 degrees, 60 degrees, 90 degrees were 2.20+0.05, 2.47+0.04, 1.62+0.05; patellofemoral joint in the inner side of the pressure in the bending of 30 degrees, 60 degrees, 90 degrees were 2.14+0.04, 2.20+0.05, 1.09+0.08.Experimental group D: lateral pressure in the bending of the knee 30 degrees, 60 degrees, 90 degrees were 2.47+0.04, 2.62+0.04, 1.54+0.04; inner pressure in the bending of 30 degrees, 60 degrees, 90 degrees is 2.20+0.05, corresponding to 2.27+0.03, 0.91+0.09.Three months after operation, through the microscope observation, found that the distal femoral trochlear depth of the experimental group with variable depth, patellar tendon down distance increased, trochlear depth is deep, and the sham operation group and control group is normal. The experimental group joint cavity inflammatory synovial hyperplasia, femoral trochlear notch shape of the loss of normal smooth contour, the surface raggedness, dark colored, C, D in experimental group showed the cracking phenomena. Trochlear deepen, loss of normal smoothness, trochlear hyperplasia with prominent, patellar tendon down distance increase, more abnormal more obviously more serious; the control group of the outer surface of bright colors, no crack. Trochlear surface layer smooth, smooth outer also cartilage. Through microscope analysis found that the experimental group cartilage thinning, some fall off, resulting in defect region, cartilage cell volume is not a, be arranged; the A group and the control group HE dyeing uniformity, cells arranged in an orderly manner, cells were similar, the surface cells look like ancient textile clothes shuttle, flat in outer layer, 4 layer structure of transparent visible, cell showing a regular distribution form.Conclusion: patella infra can increase the patellofemoral pressure, with patella infra situation more serious, patellofemoral joint between the more pressure, the pressure between the increase of patellofemoral joint can aggravate cartilage damage, cause intra-articular synovial proliferation, such as arthritis osteophyte formation.