| Part one The effect of uneven shortening patellar ligament on patellof-emoral articular cartilage on an experimental animal studyObjective:The purpose of this study was to establish an animal model which be suitable for the study of early stage of patellofemoral osteoarthritis(PF OA)and to observe the effect of uneven shortening patellar ligament on patellofemoral cartilage.Methods:Forty-eight New Zealand white rabbits were randomly divided into three groups:experimental group(n=16),sham group(n=16),and control group(n=16).In the experimental group,the patellar tendon was partially contracted,also known as the US group,and the patellar ligament was split in the middle,the medial patellar ligament was contracted for 8 mm and sutured.After 8 and 16 weeks,half of the animals were euthanised.The IS index was measured on X-ray film,the length of patellar ligament was measured on MRI,the gross observation and OARSI scores of patella and femoral condyle specimens were performed,and the microscopic observation and histopathological OARSI scores were performed.Results:The IS index of patella in control group,sham group and US group at 8 weeks were 1.61±0.12,1.58±0.23(vs.control group,P=0.772),1.65±0.19(vs.control group,P=0.591;vs.sham group,P=0.518);The IS index of patella in control group,sham group and US group at 16 weeks were1.68±0.11,1.74±0.20(vs.control group,P=0.404),1.64±0.21(vs.control group,P=0.698;vs.sham group,P=0.334),there were no statistic difference of IS index between them.The patellar ligament on MRI in control group,sham group and US group at 8 weeks were 13.38±0.95 mm,13.45±1.23 mm(vs.control group,P=0.902),and 13.79±1.24 mm(vs.control,P=0.472;vs.sham group,P=0.590),there were no statistic difference;The patellar ligament on MRI in control group,sham group and US group at 16weeks were 15.66±1.34 mm,15.89±0.90 mm(vs.control group,P=0.700),and 15.49±1.59 mm(vs.control group,P=0.815;vs.sham group,P=0.546),there were no statistic difference.The gross OARSI scores of patella in control group,sham group and US group at 8 weeks was 1.00±0.93,0.88±0.99(vs.control group,P=0.798),US group 1.63±1.06(vs.control group,P=0.230;vs.sham group,P=0.166);The gross OARSI scores of patella in control group,sham group and US group at 16 weeks were 1.25±0.71,1.25±1.04(vs.control group,P=1.000)and US group 3.88±0.83(vs.control group,P<0.001;vs.sham group,P<0.001),there were no statistic difference at 8 weeks but there were statistic difference at 16 weeks.The gross OARSI scores of femoral condyle in control group,sham group and US group at 8 weeks were 1.25±0.71,1.13±0.83(vs.control group,P=0.751),and US group 3.25±0.71(vs.control group,P<0.001;vs.sham group,P<0.001);The gross OARSI scores of femoral condyle in control group,sham group and US group at 16 weeks were 1.50±0.53,1.75±0.71(vs.control group,P=0.438),and 8.63±1.19(vs.control group,P<0.001;vs.sham group,P<0.001),there were both statistic difference at 8 weeks and at 16 weeks.The microscopic OARSI scores of patella in control group,sham group and US group at 8 weeks were 1.25±0.71,1.50±0.76(vs.control group,P=0.506),and 1.86±0.83(vs.control group,P=0.128;vs.sham group,P=0.362);The microscopic OARSI scores of patella in control group,sham group and US group at 16 weeks were 1.88±0.83,1.75±0.71(vs.control group,P=0.751),and 7.88±1.25(vs.control group,P<0.001;vs.sham group,P<0.001),there were no statistic difference at 8 weeks but there were statistic difference at 16 weeks.The microscopic OARSI scores of femoral condyle in control group,sham group and US group at 8 weeks were1.25±0.71,1.50±0.76(vs.control group,P=0.506),and 3.88±0.64(vs.control group,P<0.001;vs.sham group,P<0.001);The microscopic OARSI scores of femoral condyle in control group,sham group and US group at 16 weeks were 1.63±0.53,1.88±0.83(vs.control group,P=0.483),and10.88±1.55(vs.control group,P<0.001;vs.sham group,P<0.001),there were both statistic difference at 8 weeks and in at 16 weeks.Conclusion:The uneven shortening contraction of patellofemoral ligament could lead to degeneration of articular cartilage of patellofemoral joint,which is mild at 8 weeks and more serious at 16 weeks.The animal model of uneven shortening patellar ligament is a kind of animal model to study PF OA,especially the early changes of PF OA.Part two Histopathological changes in the infrapatellar fat pad in an experimental rabbit model of early patellofemoral osteo-arthritisObjective:The purpose of this study was to characterise the histopathological changes in the infrapatellar fat pad(IPFP)in the early stage of patellofemoral osteoarthritis(PF OA).Methods:Sixty-four New Zealand white rabbits were randomly divided into experimental(n=24),sham(n=16),and control group(n=24).In the experimental group,denoted as the patellar ligament uneven shortening group(US group),the medial patellar ligament(PL)was folded 8 mm and sutured.After 8 weeks,all animals were euthanised,and magnetic resonance imaging(MRI)evaluation,wet IPFP weight measurement,and histopath-ological and immunohistochemistry analysis were performed to analyse the histopathological changes in the IPFPs.Results:The patella ligament in three groups were 13.03±1.06 mm in control group,13.52±1.18 mm in sham group(vs.control group,P=0.348),and 13.24±1.41 mm in US group(vs.control group,P=0.678;vs.sham group,P=0.658),there were no statistic difference in three groups.The maximum cross-sectional area(CSA)of the IPFPs in the sagittal position of MRI in the control group,sham group,and US group were 45.50±7.19 mm~2,45.88±6.60 mm~2(vs.control group,P=0.907),and 53.83±8.24 mm~2(vs.control group,P=0.015;vs.sham group,P=0.035),respectively.The MRI intensity of the IPFPs in the control group,sham group,and US group were115.53±28.85 Px,108.53±26.73 Px(vs.control group,P=0.589),and154.52±18.48 Px(vs.control group,P=0.002;vs.sham group,P=0.002),respectively.The wet weight of the IPFPs in the control group,sham group,and US group were 0.32±0.05 g,0.32±0.04 g(vs.control group,P=0.895),and 0.38±0.06 g(vs.control group,P=0.017;vs.sham group,P=0.033),respectively.One osteophyte appeared in control group,One osteophyte appeared in sham group(vs.control,P=0.653),eleven osteophytes appeared in US group(vs.control,P<0.001;vs.sham group,P=0.001),the amount of osteophytes in femoral condyle in US group were more compared with that of control group and sham group,there were statistic difference.The transverse sectional area of adipocyte(under microscope,40×)were419417.69±98883.74 Px,406573.81±60236.30 Px(vs.control group,P=0.747),and 411884.83±68915.82 Px(vs.control group,P=0.831;vs.sham group,P=0.861),there were no statistic difference.The amount of adipocytes(under microscope,40×)of the IPFPs were 43.00±6.37 in control group,42.63±6.23 in sham group(vs.control,P=0.898),and 50.33±7.98 in US group(vs.control group,P=0.021;vs.sham group,P=0.034),there were statistic difference,and the amount of adipocytes in US group were increasing compared with control and sham group.The osteoarthritis research society international(OARSI)scores of the IPFPs in US group were 6.00±1.91,which was higher than the scores of 2.50±2.02(P<0.001)in control group and of 2.75±1.67(P=0.001)in sham group.The expression level of caspase-3 were 4.66±3.49 IOD/mm~2 in control group,4.31±3.00 IOD/mm~2in sham group(vs.control group,P=1.000),and 18.03±14.62 IOD/mm~2 in US group(vs.control group,P=0.018;vs.sham group,P=0.034),there were statistic difference between that of US group and that of control and sham group.The expression level of MMP-9 were 8.19±6.99 IOD/mm~2 in control group,8.19±4.02 IOD/mm~2 in sham group(vs.control group,P=0.589),and 20.05±9.58 IOD/mm~2 IOD/mm~2 in US group(vs.control group,P=0.004;vs.sham group,P=0.005),there were statistic difference between that of US group and that of control and sham group.Conclusions:In the early stage of PF OA,the histopathological changes of the IPFPs were mainly synovial stromal villous hyperplasia,synovial stromal vascular hyperplasia,inflammatory invasion,fibroblast proliferation and adipocyte proliferation,these changed could cause the anterior knee pain and articular cartilage degeneration.The histopathological changes of the IPFPs as determined via MRI and microscopic structure appeared to occur much earlier than cartilage damage in PF OA.Furthermore,detecting and treating the IPFP changes may offer aid in the diagnosis and treatment of PF OA.But the change of IPFPs in the middle and late stage of PF OA should be studied in the future.Part three Histopathological changes of the infrapatellar fat pad in advanced patellofemoral arthritis:an experimental animal studyObjective:The purpose of this study was to investigate the imageological and histopathological changes of the IPFPs in the middle and late stage of PF OA and their correlation.Methods:Ninty-six New Zealand white rabbits were randomly divided into three groups:experimental group(n=32),sham group(n=32)and control group(n=32).In the experimental group,the patellar ligament was partially contracted,also known as the US group,with the patellar ligament split in the middle and the medial patellar ligament shrunk for 8 mm and sutured.After 8 weeks,half of the animals were euthanized,MRI,wet weight measurement,and histopathological observation were used to analyze the changes and correlation of the IPFPs in the early stage of PF OA.After 16weeks,the other half of the animals were euthanized,MRI,wet weight measurement,histopathological observation were used to analyze the changes and correlation of the IPFPs in the middle and late stage of PF OA.Results:At 8 weeks after modeling,the wet weight of IPFP in control group,sham group,and US group were 0.3153±0.0418 g,0.3234±0.0464 g(vs.control grop,P=0.721),and 0.3715±0.0363 g(vs.control group,P=0.012;vs.Sham group,P=0.037),compared with the control group and sham group,the wet weight of IPFPs in US group were increased obvious,there were statistic difference;At 16 weeks after modeling,the wet weight of IPFP in control group,sham group,and US group were 0.4089±0.065 g,0.4412±0.090 g(vs.control group,P=0.425),and 0.5311±0.050 g(vs.control group,P=0.001;vs.sham group,P=0.027),compared with the control group and sham group,the wet weight of IPFPs in US group were increased obvious,there were statistic difference.The maximal cross-sectional area(CSA)of the sagittal MR images of the IPFPs at 8 weeks after modeling in the control group,sham group,and US group were 45.38±8.12 mm~2,45.5±6.30 mm~2(vs.control group,P=0.973),and 53.25±4.83 mm~2(vs.control group,P=0.034;vs.sham group,P=0.015),respectively.Compared with control group and sham group,the maximum CSA of US group was significantly increased,and there were statistical difference.The maximal CSA of the sagittal MR images of the IPFPs at 16 weeks after modeling in control group,sham group and US group were 58.63±10.57 mm~2,59.75±10.11 mm~2(vs.control group,P=0.831),and 75.63±11.25 mm~2(vs.control group,P=0.008;vs.sham group,P=0.01),respectively.Compared with control group and sham group,the maximum CSA of US group were significantly increased,and there were statistical difference.The CSA at 16weeks were higher than that at 8 weeks.The MRI intensity of the IPFPs at 8weeks after modeling in the control group,sham group and US group were125.94±29.88 Px,108.49±25.92 Px(vs.control group,P=0.233),and160.78±19.70 Px(vs.control group,P=0.016;vs.sham group,P<0.001),respectively.Compared with control group and sham group,the MRI intensity of the IPFPs in US group increased significantly;The MRI intensity of the IPFPs at 16 weeks in the control group,sham group and US group were127.33±30.89 Px,110.00±27.97 Px(vs.control group,P=0.259),and182.32±18.70 Px(vs.control group,P=0.001;vs.sham group,P<0.001).Compared with control group and sham group,the MRI intensity of the IPFPs in US group at 16 weeks increased significantly,and there were statistical difference.The OARSI histopathological scores of the IPFPs at 8 weeks were2.25±1.83 in control group,2.63±1.51(vs.control group,P=0.662)in the sham group,and 5.88±1.64 in US group(vs.control group,P=0.001;vs.sham group,P=0.001).Compared with the control and sham group at 8weeks,there was statistic difference.The OARSI histopathological scores at16 weeks were 2.50±1.51 in control group,2.75±1.83(vs.control group,P=0.770)in sham group,and 8.38±2.33 in US group(vs.control group,P<0.001;vs.sham group,P<0.001),compared with the control and sham group at 16 weeks,there were statistic difference.Conclusion:The IPFPs were accompanied by obvious histopathological and imaging changes in the early and late stage of PF OA,which occurs in the early stage of PF OA,and is gradually aggravated with the exacerbation of PF OA.The IPFPs can be used to predict PF OA or maybe evaluate the severity of PF OA after further study.The study of IPFP may provide a new method for the diagnosis and treatment of PF OA.Part four Effects of infrapatellar fat pad resection on the anatomical position of patella and cartilage of patellofemoral jointObjective:Infrapatellar fat pad(IPFP)resection causes patella baja,which adversely affects the cartilage.However,few studies have reported the effects of IPFP resection on knee structure,especially the articular cartilage.The objective of the present study was to elucidate the effects of IPFP resection on knee structure.Methods:Thirty-two white rabbits were divided into four groups(n=8)according to the IPFP procedure performed,as follows:1.no surgical procedure(control group);2.the IPFP was resected and removed(IR group);3.the medial patellar ligament was folded 8 mm to be sutured(US group);4.the patellar ligament was unevenly shortened and the IPFP was resected(IR+US group).After 8 weeks,all animal were euthanised and evaluated by radiograph,magnetic resonance imaging(MRI),MicroCT exam,gross observation,and histopathological analysis to analyse the relation between IPFP resection and anatomical position of patella and patellofemoral(PF)articular cartilage.Results:The BP index of control group,IR group,US group and IR+US group were 1.38±0.12,1.15±0.11(vs.control group,P=0.001),1.38±0.08(vs.control group,P=0.961),and 1.19±0.11(vs.control group,P=0.006);The IS index of control group,IR group,US group and IR+US group were 1.60±0.99,1.37±0.18(vs.control group,P=0.007),1.70±0.15(vs.control group,P=0.147),and 1.38±0.11(vs.control group,P=0.001);The distance from LAOP to TT in control group,IR group,US group,and IR+US group were 1.87±0.15 cm,1.60±0.20 cm(vs.control group,P=0.009),1.88±0.12 cm(vs.control group,P=0.815),and 1.62±0.16 cm(vs.control group,P=0.006);The vertical distance from TAFE to PL in control group,IR group,US group,and IR+US group were 3.81±0.52 mm,2.69±0.48 mm(vs.control group,P=0.001),3.42±0.47(vs.control group,P=0.141),and 2.69±0.73(vs.control group,P=0.004).The length of PLs in control group,IR group,US group,and IR+US group were 13.38±0.95 mm,12.33±0.75 mm(vs.control group,P=0.027),13.79±1.24mm(vs.control group,P=0.472),and 11.86±0.96 mm(vs.control group,P=0.007).The bone mineral density(BMD)of control group,IR group,US group,and IR+US group were 0.411±0.027 mg/cm~3,0.426±0.039 mg/cm~3(vs.control group,P=0.378),0.437±0.026 mg/cm~3(vs.control group,P=0.071),and 0.437±0.042 mg/cm~3(vs.control group,P=0.154),there were no significant statistic difference in PF joint in each group.There were osteophytes in each group of femoral condyle,but there were no other cartilage deformations.The amount of osteophytes that appeared on the medial edge of femoral condyle were 2 in control group,3 in IR group(vs.control group,P=0.315),7 in US group(vs.control group,P=0.041),and7 in the IR+US group(vs.control group,P=0.041);In control group,IR group,US group,and IR+US group,the OARSI scores of PF articular cartilage except osteophytes were 2.88±1.13,3.13±1.36(vs.control group,P=0.562),2.88±0.99(vs.control group,P=1.000),and 3.13±1.36(vs.control group,P=0.694).Conclusions:The IPFP is very important for maintaining normal length of patellar ligament.And,patella baja caused by the IPFP resection that leads to the patellar ligament shortening but no harm in articular cartilage in early stage;but,uneven ligament shortening can do harm in articular cartilage in early stage. |
PDF Full Text Request