Imaging Study Of Non-uniform Settlement Of Tibial Plateau And Analysis Of Its Influencing Factor-PTFJ Inclination Angle

Part one Magnetic resonance imaging study of the non-uniform settlement of tibial plateauBackgroundIn recent years,scholars have put forward the theory of non-uniform settlement of knee joint according to the principle of biomechanics to explain the pathogenesis of knee medial compartment osteoarthritis(OA).The theory of non-uniform settlement of knee joint holds that: in the process of human aging,bone mineral density and bone mechanical strength gradually decrease,resulting in bone settlement of weight-bearing bones such as tibia under the action of body weight;the supporting effect of fibula on the lateral tibial plateau and the greater load bearing of the medial tibial plateau than the lateral plateau,lead to the non-uniform settlement of the tibial plateau,i.e.,the bone settlement of the medial plateau is more severe than that of the lateral plateau;non-uniform settlement causes knee varus and increases stress load of medial tibial plateau,which in turn aggravate the non-uniform settlement;the vicious circle of non-uniform settlement of tibial plateau leads to the pathogenesis and progression of medial compartment OA.However,the phenomenon of non-uniform settlement of tibial plateau in patients with medial compartment OA has not been confirmed to date.PurposePatients with medial compartment OA without full-thickness cartilage defects of the tibial plateau were selected to exclude the influence of subchondral bone wear,and magnetic resonance imaging(MRI)images were used to evaluate whether there was non-uniform settlement of the tibial plateau in patients with knee medial compartment OA.MethodsThe data for this study are from “The Osteoarthritis Initiative”(OAI)project.The population of this study randomly selected 1600 OAI volunteers who participated in the 96 th month outpatient follow-up,and screened the volunteers who had medial compartment imaging OA of knee joint and no full-thickness cartilage defect on the articular surface of tibial plateau at the 96 th month follow-up.The software reconstructed the MRI images of the knee at baseline and 96 months,and measured the medial proximal tibial angle(MPTA)on the coronal plane.Intra observer reliability and inter observer reliability of coronal MPTA measurement on MRI were evaluated by intraclass correlation coefficient(ICC).Compare the difference between the baseline coronal MPTA and the 96 th month coronal MPTA,and calculate the difference,i.e."MPTA change".Compare the difference between male "MPTA change" and female "MPTA change".The correlations between baseline age and "MPTA change",body mass index(BMI)and "MPTA change",baseline MPTA and "MPTA change" were analyzed.Results625 volunteers(625 knees)were included in this study.271 males and 354 females;The baseline age was 45 to 79 years,and the median age was 61 years;The average BMI was 28.49±5.63 kg/m2.The ICC values of intra-observer and inter-observer reliability of the coronal MPTA MRI measurement were 0.95 and 0.89.The coronal MPTA of all included knees at baseline and 96 months were 86.11±0.84° and 84.59±1.40° respectively(P=0.000).The "MPTA change" of all included knee joints was-1.51±0.87°.There was no significant difference between male "MPTA change" and female "MPTA change"(P=0.938).The correlation coefficients between baseline age and "MPTA change",BMI and "MPTA change",and baseline coronal MPTA and "MPTA change" were-0.288(P=0.000),-0.641(P=0.000)and 0.334(P=0.000),respectively.ConclusionsIn patients with knee medial compartment OA,there is the phenomenon of varus type tibial plateau non-uniform settlement.Baseline age and mean BMI were positively correlated with the degree of varus type tibial plateau non-uniform settlement;Baseline coronal MPTA was negatively correlated with the degree of varus type tibial plateau non-uniform settlement.The reliability of coronal MPTA measurement on MRI is excellent.Part two Association between the PTFJ inclination angle and knee medial compartment OABackgroundThe strong supporting effect of fibula on the lateral tibial plateau is an important reason for the non-uniform bone settlement of the tibial plateau with low bone mineral density,and causes and aggravates medial compartment OA.Fibular support of the lateral tibial plateau is achieved through the proximal tibiofibular joint(PTFJ).From the perspective of force transmission,a lower PTFJ inclination angle can lead to greater fibular support for the lateral tibial plateau.Therefore,the inclination of the PTFJ surface may be a risk factor for medial compartment OA.PurposeTo study association between the inclination angle of the PTFJ surface and knee medial compartment OA.MethodsPatients with knee medial compartment OA and healthy volunteers were recruited.Take weight-bearing anteroposterior radiography and PTFJ radiography.Fibular inclination angle(FIA)and tibial inclination angle(TIA)of PTFJ articular surface relative to the common longitudinal axis of fibula and tibia were measured.The OA of PTFJ was graded.The intra-observer reliability and inter-observer reliability of FIA and TIA were evaluated.The differences between FIA and TIA were compared among all volunteers.The differences of FIA and TIA between the study group and the control group were compared;The volunteers in each group were divided into two age subgroups according to their age,and the differences of FIA and TIA between the age subgroups were evaluated.The odds ratio(OR)of risk factors for knee medial compartment OA was calculated.The PTFJ OA grades of the two groups of volunteers were compared.Results40 patients and 40 control volunteers were included in the study.When volunteers took PTFJ radiography,the average rotation of knee joint was 48.56±15.37°,and the median number of shots was three.The intra-observer reliability ICC values of FIA and TIA were 0.97 and 0.95,respectively,while the inter-observer reliability ICC values of FIA and TIA were 0.91 and 0.82,respectively.The mean FIA and TIA of all volunteers were 29.41±8.31° and 30.18±7.76° respectively,with no significant difference(P=0.128).The mean values of FIA(P=0.005)and TIA(P=0.000)in the study group were lower than those in the control group.The FIA and TIA of the elderly subgroup were lower than those of the middle-aged and elderly subgroup.The OR values of FIA and TIA are 5.000 and 7.154 respectively.PTFJ OA grades were higher in the study group(P=0.018).ConclusionsA lower inclination angle of the PTFJ surface is associated with a risk of knee medial compartment OA.Clinically,the early prevention of medial compartment knee osteoarthritis should be considered for middle-aged and elderly people with low PTFJ inclination angles.Programmed PTFJ radiography shooting method should be adopted to clearly display PTFJ joint space and facilitate the measurements of FIA and TIA.There was no significant difference between FIA and TIA;The measurement reliability of FIA is better,and FIA is more recommended as a prediction index.The inclination angle of the PTFJ surface in middle-aged and elderly people may decrease with age.There was a positive correlation between the grade of knee medial compartment OA and the grade of PTFJ OA.Part three Comparative analysis of the PTFJ inclination angle measured by MRI image reconstruction and the PTFJ inclination angle measured on radiographyBackgroundThe correlation between the PTFJ inclination angle and medial compartment OA is important to guide the prevention and early treatment of medial compartment OA.In the literature,measuring the PTFJ inclination angle from the PTFJ radiograph is a classic measurement modality.However,the PTFJ radiograph is not routinely taken during clinical diagnosis and treatment,and repeated X-ray transmission was required for taking the radiograph.If the PTFJ inclination angle can be accurately measured on the tomograms reconstructed from the knee MRI images,then the MRI image reconstruction can be used as an important supplementary modality to measure the PTFJ inclination angle.PurposeTo study the feasibility and reliability of reconstructing tomograms on the knee MRI images to measure the inclination angle of PTFJ surface.MethodsThe included population was volunteers who had undergone ipsilateral knee MRI within 1 year after taking PTFJ radiography in the second part of the study.On PTFJ radiography,the inclination angle of PTFJ surface relative to the common longitudinal axis of tibiofibula(X-FIA)was measured.MRI images were reconstructed by software,and the fibular inclination angle of the PTFJ surface to the longitudinal axis of both fibula and tibia(TF-FIA)and fibular inclination angle of the PTFJ surface to the longitudinal axis of tibia(T-FIA)were measured.The intra-observer reliability and inter-observer reliability of TF-FIA and T-FIA measurements were evaluated.Compare the differences between X-FIA and TF-FIA,between X-FIA and T-FIA,and between TF-FIA and T-FIA.Bland Altmann analysis was used to evaluate the consistency between TF-FIA and X-FIA,T-FIA and X-FIA.Results35 volunteers(35 knees)were included in this study.The ICC values of intra-observer and inter-observer reliability of TF-FIA were 0.97 and 0.90,respectively.The ICC values of intra-observer and inter-observer reliability of T-FIA were 0.97 and 0.92,respectively.The average X-FIA was 26.88±7.62°;The average TF-FIA was 26.59±7.50°;The average T-FIA was 31.49±8.31°.There was no significant difference between X-FIA and TF-FIA(P=0.244).There were significant differences between X-FIA and T-FIA(P=0.000),TF-FIA and T-FIA(P=0.000).Compared with X-FIA,the 95% consistency limit of TF-FIA was-0.29±2.84°;Compared with X-FIA,the 95% consistency limit of T-FIA was 4.61±6.69°.ConclusionsIt is a repeatable technique to measure the PTFJ inclination angle by calibration and reconstruction on knee MRI images.When PTFJ inclination angle is measured on MRI,if the front of knee joint is located on the left side of the measurement reference plane,the longitudinal axis of tibia rotates clockwise relative to the common longitudinal axis of tibiofibula.TF-FIA and X-FIA have good consistency,and they can replace each other.When measuring the PTFJ inclination angle on MRI,if it is necessary to compare and analyze the PTFJ inclination angle measured on X-ray and the PTFJ inclination angle measured on MRI,TF-FIA is recommended;If only the PTFJ inclination angle measured on MRI is analyzed,both TF-FIA and T-FIA can be used.Part four Study on the variation of PTFJ inclination angle with timeBackground“Part two” of the study shows that a lower PTFJ inclination angle is associated with a risk of knee medial compartment OA,and the PTFJ inclination angle in middle-aged and elderly persons may decrease with age.In “part three” of the study,the feasibility and reliability of reconstructing tomograms on the knee MRI images to measure the PTFJ inclination angle have been confirmed.PurposeBased on “part two” and “part three” of the study,this part was to further confirm the correlation between the PTFJ inclination angle and knee medial compartment OA,and to assess whether the PTFJ inclination angle changed with time in middle-aged and elderly persons,by reconstructing tomograms on the knee MRI images.MethodsThe population of the fourth part of the study was from 1600 OAI volunteers in the first part of the study.Knee joints were selected if volunteers were aged ≥ 50 years,and had medial compartment imaging OA as the main manifestation on X-ray at the 96 th month follow-up or had no obvious OA findings on X-ray at the 96 th month follow-up.Divided into "baseline OA group" and "baseline NOA group" according to whether the KL grade of medial compartment at baseline is ≥ 2;The patients were divided into "OA-96 group" and "NOA-96 group" according to whether the KL grade of medial compartment was ≥ 2 at the 96 th month.MRI images of knee joint were reconstructed and T-FIA was measured.The differences between baseline T-FIA and 96 th month T-FIA of all included knees or knees in different groups were compared.Compare the difference of T-FIA between "baseline OA group" and "baseline NOA group",and compare the difference of T-FIA between "OA-96 group" and "NOA-96 group".Results943 volunteers(1657 knees)were included in this study.The average T-FIA of all included knees at the 96 th month was 3.92±2.38° smaller than that at baseline(P=0.000).The T-FIA of "baseline OA group" at the 96 th month was 2.88±2.08° smaller than that at baseline(P=0.000).The T-FIA of "baseline NOA group" at the 96 th month was 4.50±2.36° smaller than that at baseline(P=0.000).The T-FIA reduction of the 96 th month relative to baseline in the "baseline NOA group" is greater than that in the "baseline OA group"(P=0.000).For knees without medial compartment OA at baseline and with medial compartment OA at the 96 th month,the T-FIA at the 96 th month was 3.94±2.02° smaller than that at baseline(P=0.000).At baseline,T-FIA in "baseline OA group" was 5.39° smaller than that in "baseline NOA group"(P=0.000).At the 96 th month,T-FIA in “OA-96 group” was 3.73° smaller than that in “NOA-96 group”(P=0.000).ConclusionsA lower PTFJ inclination angle is associated with an increased risk of knee medial compartment OA.In middle-aged and elderly persons,the PTFJ inclination angle gradually decreases with the increase of age and the settlement of PTFJ;Among them,the PTFJ inclination angle of the knee without medial compartment OA decreased more pronounced than that of the knee with medial compartment OA.When the PTFJ inclination angle of patients without knee medial compartment OA decreases,the risk of medial compartment OA will increase.A larger PTFJ inclination angle is a morphological reserve for the prevention of knee medial compartment OA.