| ABSTRACTObjective: To Measure the contact stress of knee medial compartment using pressure sensitive piece of technology, by genu varus angle, which is 0, 2, 4, 6...30 degrees. Through the study in the Knee Medial compartment contact pressures by Angle changes of genu varus to provide some reference information for the treatment of genu varus osteoarthritis.Methods:Choose lower limb specimens from 3 fresh adult male corpse(the 3 cases from the left side, the other 3 cases from the right, respectively from three adult male corpse). The mechanical force line of lower limbs were 0°, femoral tibial Angle were 172 ° after Strict measured(The knee was no varus deformity). Each knee had joint clearance symmetry and articular cartilage integrity, but bone of each knee had not obvious bone change and anatomic variations by X-ray. Six cases of lower limb specimens from 3 corpses stay away from the middle of femur,then remove the soft tissue, keep 25 cm in the femur distal, and keep 25 cm tibia and fibula proximal.。When stripping out the soft tissue around the knee joint, keep emphatically the lateral meniscus within the knee before and after cruciate ligament, so as not to affect the normal tibial articular contact stress, Reserve the integrity of superior tibiofibular ligaments, tibiofemoral joint and patellofemoral joint during operation. There are six sets of knee joint bone specimens finally。The 6 cases of knee joint bone specimens of proximal tibia were done the osteotomy according to 2 cm from under the tibial articular surface, then fixed with outboard proximal tibia anatomic plates. In the end, Special anatomical plate designed by ourselves fixed at both ends of osteotomy。femoral tibial Angle were 172 °after the surgery。Adjust the angle of Special-shaped steel plate to observe the stress variation in the measurement of knee medial compartment.Results:With the increasing of Angle of genu varus, the knee medial compartment stress increases gradually in every knee joint bone specimens, When genu varus Angle of 0 degree, stress value of the medial compartment was 1.611±0.363 MPa. With genu varus Angle gradually increased from zero to 10 degrees, the medial compartment stress value increase significantly was 5.113±0.796 MPa. When the Angle increased to 14 degrees, the medial compartment stress value was 8.032±1.088 MPa. With the increasing of Angle, knee medial compartment stress value began to gradually reduce, When genu varus Angle of 30 degrees pressure stress value was 2.009±0.386 MPa.The difference of measurement data among the groups were analyzedby homogeneity test of variances using Bartlett method, and one-way analysis of variance was used under an equal condition. As the change of genu varus angle, knee medial compartment of stress and change. The data is statistically significant.(χ2=18.976,P<0.01)。Conclusion: With the increase of Angle of knee varus, knee medial compartment of the stress value has changed significantly, and reached a peak in 14 degrees. So the genu varus Angle was smaller, the smaller the stress of knee medial compartment. Through the wedge osteotomy will move the stress to the knee joint lateral and reduce the contact stress of the medial tibia femoral joint to improve uneven articular surface stress state, which is maybe One of the mechanisms of the treatment of knee medial compartment osteoarthritis. But with continuing to increase as genu varus Angle, the stress value of the medial compartment began to transfer to the knee medial rim, where the stress was focus on. Many factors will affect the knee medial compartment bearing load, such as weight bearing, bearing time, knee joint position, tibial articular contact area size, degree of deformity articular cartilage degeneration, osteophyte formation and experimental methods, etc. With genu varus Angle increased again(14°-30°), the stress on Knee joint will be moved to the interior between the medial side. Compartment, Variation of Stresses... |
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