| Part 1 Finite element analysis of patellofemoral joint pressure changes during knee joint exerciseObjective:Healthy patellofemoral mechanics is essential for optimal knee function.The main function of the tibia is to form a knee extension device with the surrounding ligament and support belt,which carries the quadriceps load and can effectively extend the knee lever arm.Changes in the position and morphology of the tibia lead to patellofemoral ligament strain,soft tissue damage,and/or knee pain.In addition,the wrong patella trajectory may result in large joint response loads and high stress in articular cartilage;these factors increase the risk of cartilage wear and the development of skeletal abnormalities that ultimately lead to osteoarthritis.Although the mechanical origin of patellofemoral joint dysfunction is unclear,there is a link between patella trajectory tracking and soft tissue pathology and abnormal kinematics.In this study,the finite element analysis was used to investigate the changes of the pressure on the tibial articular surface during knee joint exercise.Method:Three fresh frozen cadavers(all male,mean age of 55.3 years(range 44-72),mean height of 180.3cm(range 175-183),mean weight of 91.5kg(range 70-127)were thawed at room temperature and,femur and tibia bones were sectioned approximately 20 cm from the knee joint line.All soft tissue beyond 10 cm of the joint was removed from the bones except quadriceps and hamstring muscles.Knees were examined and found to have no visible signs of injury.Following computed tomography(CT)and magnetic resonance(MR)imaging,a series of dynamic in-vitro tests were performed on the cadavers in a muscle loading rig(MLR)as described by Shalhoub andMaletsky.The MLR mounted the knee joint in an inverted position,such that the femur was rigidly attached and the tibia was allowed to move freely.Quadriceps and hamstring tendons were clamped and passed through a series of pulleys to maintain a physiological orientation to the joint.A stepper motor and a 1300 N load cell were connected in-line with the quadriceps clamp to produce deep knee flexion to approximately 120° and to measure the resulting quadriceps load.The quadriceps line of action was applied through the combined tendons of the rectus femoris and vastus intermedialis.In addition,a static weight of 89 N was applied to the semimembranosus and biceps femoris hamstring muscles.An Optotrak 3020 motion capture system(accuracy with in 0.04° and 0.03mm)was used to record tibiofemoral and patellofemoral kinematics.The established normal humerus finite element model was introduced into ANSYS software to create model skin and finite element geometry,and simulate the compression of the tibial articular surface when the knee joint was straightened and flexed at 30°,60°and 90°.Results:For both the computational and experimental data,pressure tended to be concentrated on the lateral facet of the patella,with the lateral concentration larger for the loading condition including the hamstrings.The average lateral force ratio varied from 0.67 to 0.82 over all flexion angles and loading conditions.The lateral force ratio was significantly(P<0.01)larger with the hamstrings loaded than unloaded for all conditions except for the computational data at 40 deg.For the computational data,loading the hamstrings increased the average lateral force ratio by 0.03-0.04 at the individual flexion angles,compared to 0.05-0.07 for the experimental data.The computational lateral force ratio was not significantly different from the experimental data at any flexion angle.The lateral distance from the patellar ridge to the center of force was significantly larger(P<0.004)with the hamstrings loaded than unloaded for all conditions except for the computational data at 40 deg.For the computational data,loading the hamstrings increased the average lateral position of the center of force by 0.6-0.9mm at the individual flexion angles,compared to 1.1-1.3mm for theexperimental data.For the computational data,patellar flexion,lateral shift,and lateral tilt tended to be larger.Loading the hamstrings increased the average patellar flexion by 1.0 deg-2.6 deg for the two methods,with the change significant(P<0.01)for every comparison.Loading the hamstrings increased the average thelateral tilt by 0.1 deg-0.5 deg for the two methods.The changes were significant for the computational data(P<0.01)but not for the experimental data(p=0.05 at 40 deg,p>0.1 at 60 deg,80 deg).Loading the hamstrings increased the average lateral shift by 0.2 deg-0.5 deg for the two methods,with the change significant at 60 deg and 80 deg for the computational data(P<0.04).Conclusion:The finite element analysis proves that the joint surface of PFP patients is more stressed than normal people during knee flexion.Moreover,the stress is concentrated on the outside of the humerus,and theoretically,the tension on the outside can be released to obtain a good effect.This result has certain guiding significance for clinical treatment.Part two Clinical study on pressure change during patellofemoral joint movementObjective:Patellofemoral joint pain is a highly common and disabling pathology.In theory,the pressure on the joint surface is one of the causes of pain in the patellofemoral joint.Biomechanical models of cadavers have been used to explain the etiology of patellofemoral pain.However,currently,there is no effective data on quadriceps torque in patients with patellofemoral joint pain,which hinders the application of individualized programs in clinical treatment.Although increased joint surface compressive stress is considered as one of the important causes of idiopathic Patellofemoral pain(PFP),it is still necessary to conduct invasive procedures to directly measure joint stress.Therefore,the cadaver model is often used to infer the stress of the patellofemoral joint surface.However,in vitro experiments make the reliability of results overly dependent on artificially set parameters.Therefore,a new measurement method is needed to quantify the patellofemoral contact force per unit of tibial tip torque.The purpose of this study was to :(1)measure theeffective force arm of quadriceps femoris in patients with patellofemoral joint pain and compare it with the control group;(2)explore the quantitative method of contact force of patellofemoral joint surface in dynamic activities.Method:This study was divided into two groups.Patients admitted to the third hospital of hebei medical university from October 2016 to April 2018 were selected as PFP patients with patellofemoral joint pain.Inclusion criteria: 1.2.Patients with typical patellofemoral joint pain have pain history of more than 3 months;3.Normal muscle strength of lower limbs.Exclusion criteria: 1.Limited knee movement;2.2.Patients with obvious patellar dislocation;3.Previous knee surgery or invasive operator;4.Those who cannot receive MRI examination due to metal implants in their bodies.Finally,8 patients with Patellofemoral pain(PFP)were selected.There were 2 males and 6 females.6 cases were unilateral and 2 cases were bilateral.There were 4 cases of left knee and 6 cases of right knee.The mean age was 31 years(27-36 years),and the mean duration of pain was 8.3 months(3-11 months).Another 10 volunteers without patellofemoral joint pain were recruited as the control group.No lower limb trauma and surgical history were found in the control group.The MRI results of the two groups were analyzed using the same method.To rule out potential pathological changes,we first performed MRI of the knee in neutral position.The patient was placed in supine position for MRI examination.The knee joint was fully extended,the quadriceps was relaxed,and the feet were in neutral position.Static knee MRI scan done completely bend your knees,respectively,in the process of stretching knee in knee flexion Angle of 40 °,30 °,20 °,10 ° : MRI scanning,keep foot leaving examination table in order to maintain quadriceps tension.After the examination,the sagittal plane images with the largest patella were selected from the image results of each group for analysis.The patellofemoral joint surface stress is obtained by substituting the image measurement results into the known formula.SPSS13.0 software was used for statistical analysis of the data(IBM,Armonk,NY).Anova was used to detect the effect of knee Angle on patellofemoral joint surface stress.The difference between the two groups wasanalyzed by T test,and P<0.05 was considered statistically significant.Results:A total of 18 subjects participated in this study,including 8 patients with patellofemoral joint pain and 10 knees in the PFP group.The control group consisted of 10 healthy volunteers.There was no significant difference in the demographic data of patients in each group(Table 1).The results showed that knee joint Angle was the main factor affecting Fpt/Fq,EQma and PTma(table 2).Meanwhile,knee joint Angle was the main factor affecting Fr/Mtib and Fr/Fq(figure 2).Fr/Mtib 10 ° of knee joint in the PFP group show,increased significantly when 20 ° and 30 °.Overall,Fr/Fq was greater in the PFP group than in the control group.All knee angles had significant differences in Fr/Mtib and Fr/Fq(table 2).At all knee flexion angles,the quadriceps Angle of the PFP group was greater than that of the control group.Conclusion:Currently,there is no effective data on quadriceps torque in patients with patellofemoral joint pain,which hindersthe application of individualized programs in clinical treatment.Although increased joint surface compressive stress is considered as one of the important causes of idiopathic Patellofemoral pain(PFP),it is still necessary to conduct invasive procedures to directly measure joint stress.Therefore,the cadaver model is often used to infer the stress of the patellofemoral joint surface.However,in vitro experiments make the reliability of results overly dependent on artificially set parameters.Therefore,a new measurement method is needed to quantify the patellofemoral contact force per unit of tibial tip torque.In this study,an effective method to evaluate patellofemoral joint surface stress was obtained by measuring MRI images of knee joints at different flexion angles.Part three Study on the nomenclature and minimally invasive treatment of lateral impingement injury of patella with Wiberg type III and IVObjective:Patellofemoral joint injury and pain can be seen in people of all ages,and patellar lateral injury is more common in young and middle-aged people [1,2,3].Knee joint is one of the most commonly used joints in human life.Knee joint injury or pain will affect patients' movement,life and work.Patellofemoral joint pain can be induced by patellar tilt,excessive load of patellar subchondral bone,and peripatellar support belt [5,6].Persistent patellofemoral joint pain will lead to patellofemoral arthritis and pain in the peripatellar support zone,etc.[6].For LPCS patients have abnormal bony structure,we think in the knee flexion,Lateral Patellar articular surface and the Lateral femoral condyle impact block,this mechanism under similar acromion Impingement,the Impingement femoral head,resulting in a series of symptoms and signs,similar to the LPCS called Patellar Lateral Impingement(Lateral Patellar Impingement Syndrome,LPIS).We believe that the patellofemoral joint can be modified by arthroscope-assisted dressing without injury to the lateral support band,which can also change the match-and-match relationship of the patellofemoral joint and avoid the occurrence of the above complications.In this study,a mixed cohort study was conducted to investigate the effect of ALP in the treatment of LPIS,so as to provide a reliable method for the clinical treatment of patellofemoral joint pain.Method:Patients were selected from the department of joint of the third hospital of hebei medical university who were hospitalized from September 2016 to March 2018 due to patellofemoral joint pain.Inclusion criteria: 1.Aged 18~60 years old;2.Clinical characteristics: the knee joint pain of squatting and standing up,walking up and down stairs was obvious and affected walking,and there was occasionally noose and leg beating during walking.Local examination of knee joint: anterolateral patella tenderness,patella mobility is limited,and friction sound can be heard.3.Ultrathin CT scan and MRI examination of the knee joint: according to wiberg type III and type IV patella.Exclusion criteria: 1.Elderly patients(>60 years old);2.2.Patients with non-anatomical structural abnormalities,such as patella fracture malunion;3.Mechanical knee joint injury,such as meniscus injury,ligament injury,patella fracture malunion,etc.;4.Injuries caused by bacterial inflammation of the knee joint;5.Patients with patellar dislocation and subluxation;6.Patients with severe osteoarthritis or ligament repair found inclinical diagnosis,imaging examination or arthroscopic examination;6.A total of 38 patients(38 knees)were included in this study,including 15 males and 23 females.There were 17 cases of left knee and 21 cases of right knee.The mean age was 26.2 years(12-50 years),and the mean time of pain was 19.3 months(1-60 months).Results:A total of 38 patients(38 knees)were included in this study,including 15 males and 23 females.There were 17 cases of left knee and 21 cases of right knee.The mean age was 26.2 years(12-50 years),and the mean time of pain was 19.3 months(1-60 months).In all cases,prominent lateral patellar abnormalities are seen.During the operation,some cartilage injuries were confirmed,including 14 cases of articular cartilage injuries in the superior region of patella and 18 cases of articular cartilage injuries in the lateral region of patella.All 38 cases were followed up for 10-21 months,with an average of 14.0 months.During the period,there was no infection,no joint hematocele or effusion,and no joint movement restriction.35 people returned to their original jobs or continued to engage in previous sports activities.Two patients were treated with total knee arthroplasty 40 months after surgery and 35 months after surgery due to severe osteoarthritis,respectively.One patient was treated with patellofemoral ligament surgery in a local hospital for pain recurrence and progressive aggravation of the knee joint 11 months after surgery.The Lysholm score of knee function is shown in table 1.The difference between postoperative and preoperative Lysholm score of the knee joint was an average of +1.26 points(-2~+5 points),and the difference between preoperative and postoperative Lysholm score was statistically significant.Conclusion:In this study,arthroscopic lateral patellar plasty was performed according to the patient's condition,and the treatment of lateral patellar impingement syndrome was an effective,necessary,minimally invasive and simple method.This study proposes the treatment principles for lateral patellar hypertension syndrome,which is of guiding significance for the clinicaltreatment of patellofemoral joint pain... |
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