Anatomical Characteristic Study On Chinese Femoral Anterior Condyles And Modified Design Recommendation Of Knee Joint Prosthesis

Part I: Parameters measurement of Chinese femoralanterior condyles based on3D-reconstruction technologyObjective To reconstruct the healthy unilateral lower limbs of CT and distal femurcartilage MR images of a sample of200cases and use SEA for the rotational alignmentmarker line through the professional software,anterior flange bone cut is simulated andmeasure the thickness of the medial and lateral anterior condyles,cartilage thicknessincluded.To measure the parameters of Chinese knee anterior condyles and observe thedifference between genders,find the difference from the imported prostheses of TKA andoffer a proposal to the design of a prosthesis femoral component adapted to Chineseanterior knee condyles.Methods Reconstruct bone CT and cartilage MR images of the selected sample ofthe unilateral knee,then switch to the software of UG NX6.0and make sure of theintegration of the3-dimensional images of the bone and the cartilage,when SEAdetermined,simulated bone cut was operated on the anterior condyles and measure thethickness of the lateral and medial anterior condyle,that is the distance between the top ofthe anterior condyle and the bone cutting surface,the distance between the top of the lateralor medial anterior condyle and the bone cutting surface is defined as h1or h2,the distancebetween the top of the lateral anterior condyle and PCA is defined as AP,calculate the rateof h1/AP and h2/AP,observe the differences between humanbody and three kinds ofprostheses and between genders;observe the difference of the trochlear groove of thehuman body and the prosthesis.Results1. h1/AP of human body and the prostheses,the two-sample t test showed:Male: t₁=11.9,P₁﹤0.05;t₂=7.9,P₂﹤0.05;t₃=1.4,P₃﹥0.05.Female:t₁=19.5,P₁﹤0.05;t₂=13.2,P₂﹤0.05;t₃=5.0,P₃﹤0.05.There was no significant difference of the thickness of lateral anterior condylebetween the male and Zimmer Gender Knee,while significant difference was foundbetween the male and the other2prostheses.There was significant difference of the thickness of lateral anterior condyle betweenthe female and all3prostheses.2. h2/AP,the two-sample t test showed: Male:t₁=34.3,P₁﹤0.05;t₂=26.6,P₂﹤0.05;t₃=18.1,P₃﹤0.05.Female:t₁=38.8,P₁﹤0.05;t₂=29.5,P₂﹤0.05;t₃=17.4,P₃﹤0.05.There was significant difference of the thickness of medial anterior condyle betweenthe human body and3prostheses.3. h2/AP between the male and the female,the two-sample t test showed: t=4.5,P﹤0.05.h1/AP between the male and the female,the two-sample t test showed: t=8.9,P﹤0.05.4. Thickness of the trochlear groove of the3kinds of prostheses range from3.2mm to4.5mm.Thickness of the trochlear groove of humanbody was0.3±0.6mm of the male and0.2±0.3mm of the female.There is significant difference between the humanbody and the prostheses.Conclusions1. Only the lateral anterior condyle design of Zimmer Gender Kneematches Chinese males among the3prostheses,the medial and lateral anterior condylesdesign of other prostheses are obviously bigger than Chinese and the trochlear groovedesign was too thick.2. There are differences of both the lateral and medial anterior condyles thicknessbetween genders.3. Prosthesis design of the femoral component:trochlear groove of the anteriorcondyle should be deeper and both lateral and medial anterior condyles should be thinner.Part II:Study of the morphology of femoral anteriorcondyles bone cutting surface and its visual impactidentity based on3-dimensional CT reconstructionObjective To reconstruct the CT-scan images of200healthy Chinese unilaterallower limb of Part I and simulate TKA bone cut on the femur anterior flange on the basisof the different rotational alignments,observe the coronal morphology of the bone cuttingsurface and the difference between the Chinese and Caucasian, demonstrate the visualidentity based on correct rotational alignment in TKA and observe the difference of theposterior condylar angles between the gender of Chinese. Methods To draw an item of200CT-scans of Chinese unilateral lower limb atrandom from our image database,of which116cases are males,84females. Scan slicethickness is1.25mm of the cross section and0.7mm of both coronal and sagittalsection.The reconstructived3D images of the knee were clear enough and bone landmarksanatomical characteristics are not heteromorphosis.The imaging data is3-dimensionalreconstructed through the software of mimics10.01and the3D reconstructed images areimported into the UG NX6.0software, SEA, CEA,PCA and the3°external rotationalPCA is used as the rotational alignment marker line of the distal femur,respectively;bonecut of anterior condyles is simulated and observe the amount of three kinds of signs ofbone cutting surfaces after three signs defined in the coronal plane.To measure theposterior condylar angles of Chinese and observe its difference between genders.Results1. Measurement result of the posterior condylar angle is （4.7±0.8）°（range2.9°to6.4°）of men and （3.1±1.1）°（range0.8°to6.1°） of women.To test the posterior condylar angle and external rotational PCA for3°of the male bysingle sample t-test: t=11.9,P﹤0.05,there was significant difference of the angle betweensexes.2. To test the posterior condylar angle and3°which is the external rotational angle ofPCA by single sample t-test:Female: t=0.83,P﹥0.05,there is no significant difference.Male: t=22.9，P﹤0.05，there is significant difference.3. Included angles of SEA and CEA of male or female were both in accordance withnormal distribution.Male:（3.5±0.4）°（range2.5°to4.7°）.Female:（3.2±0.7）°（range1.4°to5.3°）.It is not suitable to compare the included angle with0°of the same sex.But theincluded angles between genders could be compared by the two-sample t test in order toconclude whether there was difference of external rotation between genders: t=3.83,P﹤0.05, there is significant difference between genders.4. When SEA is used for the rotational alignment marker line,the “boot signs” aresignificantly more than the “grand-piano signs”（101vs15） of the anterior condyles bonecutting surface in the coronal plane of the male,while the “grand-piano signs”are more thanthe “non-grand-piano signs”（68vs16）of the female significantly.When SEA or external rotational PCA for3°is used for the rotational alignment marker line,respectively,we observe the difference of the amount of the “grand-piano signs”and the “boot signs” by Chi-square test:male χ²=6.20,P﹤0.05，the difference is significant；female：χ²=1.22,P﹥0.05，there is no significant difference between the two lines.Conclusions1. There is significant difference of the posterior condylar anglebetween the Chinese male and female.The distribution of the posterior condylar angles ofthe female are more discreter than male.2. In the male,there is significant difference of about1.7°included angle between theSEA and the external rotational PCA for3°,so if PCA is used for the rotational alignmentmarker line in TKA,a larger external rotational angle is suggested.While in the female,anexternal rotational PCA for3°line can be used for the rotational alignment marker line.3. It is not suitable for CEA to be regarded as the rotational alignment markerline,otherwise,we may have an over external bone cutting surface of the anteriorcondyles,and it is more serious in the male than that in the female.4. When TKA operated on Chinese patients, we should take the “boot sign” of theanterior condyles bone cutting surface as the correct rotational alignment visual identity ofmen because of lower error probability,while in women, the “grand-piano sign” is moresuitable.The visual impact of the anterior condyle bone cutting surface maybe inaccuratebecause of the individual difference,so the bone cut of the anterior condyles should bedetermined by the standard line of SEA.