Experimental Study On The Effect Of Patellar Shift On Patellofemoral Joint Pressure

BackgroundWith the increasing aging of the population in our country,knee osteoarthritis has become one of the most common diseases in the outpatient and inpatient causes of middle-aged and elderly people.According to statistics of the World Health Organization,knee osteoarthritis is expected to be reached by the end of 2020.It will become the fourth leading cause of disability,long-term knee pain and walking difficulties seriously affect the quality of life of such patients,but also to a large number of elderly patients with great mental problems;study found that the main cause of knee pain Pain caused by tibial tilt and patellofemoral joint wear is an important factor,and through clinical work can be found in patients with knee osteoarthritis only showed symptoms of simple patellofemoral arthritis about 67% of patients,so the patellofemoral joint Inflammation is considered to be a major component of the specific breakdown of osteoarthritis of the knee.Currently,in the clinical treatment of patello-femoral arthritis,whether it is the use of conservative treatment such as medication,physical therapy,and functional exercise,or around the joint Surgical treatment methods such as release and contraction of the lateral support band are all based on the mechanism of changing pathological biomechanics.Relieve symptoms and improve knee function;patellofemoral arthritis is defined as a loss of articular cartilage or both surfaces of the patella and the trochlear groove.The most extensive wear of the sacrum is the lateral aspect of the sacrum.Joint lateral arthritis is not necessarily caused by disordered,but the outer side surface of the patella is indeed easier than overloading the central or medial patella.This suggests that there is some degree of tilt or misalignment in the etiology of lateral arthritis.At present,studies at home and abroad show that the use of clinical means to move the patella can effectively relieve the symptoms of sacroiliac arthritis.However,no changes in the pressure between patellofemoral joints before and after intrapatellar shift have been observed.There has been no observation of patellofemoral pressure at different knee flexion angles.There is no specific biomechanical study to analyze whether the pressure changes are statistically significant.ObjectiveIn this experiment,the changes in pressure between patellofemoral joints before and after tibial internal fixation were studied by using the knee joint model of cadaveric specimens.By further comparing the pressure changes between the tibiofemoral joints after the tibial displacement,the effect of tibial internal displacement on the tibiofemoral joint pressure was observed.To provide a biomechanical basis for the treatment of patellofemoral arthritis in clinical treatment.Study TypeCadaveric study MethodsSix human knee joint specimens(specific age and sex are unknown)were selected to exclude soft tissue and ligament injuries around the knee joint,and to eliminate fractures and other diseases;the joints were disarticulated and removed from each knee joint 20 cm apart from the line.Subcutaneous fat,carefully retain the quadriceps tendons,joint capsules,intact bony tissue and surrounding ligaments;the prepared knee joint specimens were placed in a refrigerator at-20 °C,thawed 24 hours before the start of the experiment,and the specimens were fixed on the knee joints.On a special holder,simulate knee extensions,flexion 30°,45°,and 60°.Place the pressure transducer on the patello-femoral joint and pressurize the quadriceps tendon axially with a 200 N load to remove the pressure sensor.And record the pressure value.Relocation: Displace the patella outward by 10 mm.Repeat the above operations to record the pressure between the patellofemoral joints.Move inside: shift the patella inward by 10 mm.Repeat the above operations to record the pressure between the patellofemoral joints.The pressure of the patello-femoral cartilage was measured by the RFP603 pressure sensor test system.The biomechanical results of all measured angles at the physiological position,inward shift,and external shift were taken at each time for 10 sets of data,and the measurements were repeated 3 times and averaged.Results1.In the knee extension position,the pressure between the patella femoral joint external surface after the patella was in the physiological position,after the internal shift,and after the external shift was: 26.038±0.918,14.922±1.155,34.104±2.020;Significant difference.2.When the knee joint was flexed at 30°,the pressure between the patella femoral joints was 57.430±1.844,36.087±7.561,and 83.769±9.548,respectively.There are significant differences.3.At the knee flexion angle of 45°,the pressures between the iliac femoral joint outer surface and the patella in physiological position were respectively 72.972±2.733,56.770±2.706,and 110.668±6.895.There are significant differences.4.In the knee flexion position of 60°,the pressure between the patella femoral joint outer lateral surface after the patella was in the physiological position,inward shift,and outward shift was 106.436±1.580,80.896±3.812,and 127.758±1.246,respectively;There are significant differences.Conclusion1.In the different experimental knee flexion angles,the pressure of the patellofemoral joint increased relative to the physiological position after the metatarsal dislocation,and the inter-femoral joint pressure decreased compared with the physiological position and the relocation condition,and the flexion angles shifted downwards.After the pressure is reduced differently.2.The trajectory of the normal patella shifts slightly to the lateral side.When the unilateral pressure in the lateral chamber is too large,patello-femoral arthritis is often caused.After the patella is shifted inward,it can be corrected to effectively reduce the cartilage pressure outside the patello-femoral joint.