Morphological Changes Of Femoral Posterior Condyle In Femoral Trochlear Dysplasia With Patellofemoral Joint Instability Were Observed With The Aid Of CT

Purpose: Patellofemoral instability is a very common disease in the daily clinical work of orthopedics,and this disease can greatly affect the daily habits of patients,thus their life quality decrease deeply.The pathogenesis of patellofemoral instability is complex and varied,and usually,it is frequently divided into bony structural abnormalities and soft tissue structural abnormalities which based on the characteristics of the anatomical structure of the knee joint.The distal femoral trochlea groove has a physiological anatomical disorder due to its geometric shape and geometric depth,and the abnormal shape of the medial and lateral femoral condyles can directly lead to a stable bony alignment between the patella and the femoral trochlea,while most of the previous scholars studied the trochlea morphology and correlation coefficient measurements.The aim of this study was to obtain morphological data of the posterior femoral condyle in patients with patellofemoral instability due to trochlear dysplasia and in normal subjects,and to compare whether there were morphological differences by measuring the correlation data and by statistical methods.Methods: This experiment retrospectively analyzed 58 patients who attended our hospital from 2019 to 2022,of whom a total of 30 patients with 35 affected knees diagnosed with patellofemoral instability due to f trochlear dysplasia(experimental group)and 28 normal patients with 35 normal knees in the same time period(control group).Several knee imaging(CT)measurements were performed on the knees of both groups: the level with the largest area of the femoral epicondyle was found and selected in cross-section,and the widths of the medial and posterior femoral condyles and the medial and lateral condyles,the distance from the medialmost posterior aspect of the medial femoral condyle to the highest point of the lateral femoral glide and the distance from the last lateral aspect of the lateral femoral condyle to the highest point of the medial femoral glide were measured and the angle formed by these two lines was measured.The sagittal plane was then selected,and the longest and highest levels of the medial and lateral condyles were selected,respectively,and the lengths of the medial femoral condyle,posterior femoral condyle,lateral femoral condyle,and posterior femoral condyle,as well as the heights of the posterior medial femoral condyle and posterior lateral femoral condyle were measured and recorded.In addition,the ratio of the width of the medial and lateral posterior femoral condyles to the width of the medial and lateral condyles;the ratio of the width of the medial and lateral posterior femoral condyles;the ratio of the length of the posterior condyle of the medial femoral condyle to the medial femoral condyle and the posterior condyle of the lateral femoral condyle to the lateral femoral condyle;the ratio of the length of the medial and lateral posterior femoral condyles;the ratio of the height of the medial and lateral posterior femoral condyles;the ratio of the distance from the medial most posterior femoral condyle to the highest point of the lateral femoral glide to the height of the lateral posterior femoral condyle,respectively.The ratio of the distance from the most medial posterior femoral condyle to the highest point of the lateral femoral glide to the highest point of the medial femoral glide.All data measured by MIMICS were tested for reliability and retest reliability using the intra-group correlation coefficient(ICC)method.All data were processed and analyzed using R language software to compare various morphological parameters in posterior condyle imaging between the two groups,and statistical tests for each parameter in the two groups were performed using the two-sample rank sum test(Mann-Whitney U Test),and then all morphological factors that had statistical differences in the univariate analysis,as well as age and gender,were included in the multifactor logistic regression analysis.To further determine which abnormal morphological factors of the posterior femoral condyle are independent risk factors for patellofemoral joint instability.Result: The intra-group correlation coefficients(ICC)for all measurement-related data in the two groups ranged from 0.95 to 0.99.There was no significant difference between the widths of the medial and lateral posterior condyles and the widths of the medial and lateral condyles in the two groups;there was no significant difference between the distances from the medial posterior condyle to the outside of the slide and the distance from the lateral posterior condyle to the inside of the slide.There was no significant difference in the comparison of the distance from the medial posterior condyle to the outside of the slide and the distance from the medial posterior condyle to the inside of the slide.ratio were statistically significantly different in(P<0.001).In the sagittal plane,there was no statistically significant difference between the heights of the medial and lateral posterior condyles and the ratios of the heights of the medial and lateral posterior condyles in the two groups;there was no statistically significant difference between the lengths of the posterior epicondyles,the epicondyles,and the medial condyles in the two groups;there was no statistically significant difference between the ratios of the lengths of the posterior and lateral condyles in the two groups;there was a statistically significant difference between the lengths of the posterior and medial condyle length ratio compared with the posterior medial condyle length ratio in the two groups was statistically significant(P<0.001);the difference in the ratio of the length of the posterior medial condyle to the posterior lateral condyle in the two groups was statistically significant(P=0.005;).Evaluation of multifactorial logistic regression analysis: the effect of medial posterior condyle length on posterior condyle morphology was statistically significant [OR= 0.779,95% CI(0.620,0.979),P=0.032],and the ratio of medial posterior condyle length over medial condyle length on posterior condyle morphology was statistically significant [OR= 1.754,95% CI(1.189,2.588),P=0.005],the ratio of the width of the medial posterior condyle to the width of the lateral posterior condyle had a statistically significant effect on the morphology of the posterior condyle [OR= 1.173,95% CI(1.048,1.314),P=0.006],the ratio of the diagonal distance between condyles had a statistically significant effect on the morphology of the posterior condyle [OR= 1.206,95% CI(1.037,1.402),P=0.015].Conclusion: This study found that the morphology of the posterior condyles of patients with patellofemoral instability due to trochlear dysplasia was different from that of normal human posterior femoral condyles.The ratio of the intercondylar diagonal distance was greater than the normal intercondylar diagonal ratio.The posterior condyles of patients with patellofemoral instability due to femoral talus dysplasia may have differences in morphology relative to the normal posterior femoral condyles,and the posterior condyle deformity caused by such differences may be a combined deformity of the length and width of the inner and outer posterior condyles,which should draw the attention of orthopedic surgeons in the future diagnosis and treatment of patellofemoral instability,and may have some reference significance for the future surgical treatment of osteotomy.