| BackgroundThe design of shoulder prosthesis is developing rapidly from monobloc prosthesis of the first generation to 3D anatomical prosthesis of the fourth generation.The design of the fourth generation of shoulder prosthesis is based on the precision measurement for bone geometry of the glenohumeral joint.The values were obviously different among previous kinds of measurements,with constrainted clinical application.So,it is very important to explore the method to measure bone geometry of the glenohumeral joint with postprocessing technique of multi-slice spiral CT.ObjectiveTo evaluate the method and its initial application of postprocessing technique with multi-slice spiral CT in measuring bone geometry of the glenohumeral joint so as to provide some reference data for design of Chinese shoulder prosthesis.MethodsFifty-one dry humerus specimens including 23 right humeri and 28 left ones,50 dry scapula specimens including 26 right scapulas and 24 left ones and 50 wet anticorrosive shoulder specimens of Chinese adults including 21 right shoulders and 29 left ones were scanned with Siemens Somatom Sensation 16 scanner.The images were delivered to LEONARDO workstation and were analyzed with postprocessing technique of multiplanner reformation(MPR) and volume rendering technique(VRT).The parameters of humerus included retroversion angle,inclination angle,medial offset,posterior offset, articular surface diameter,radius of curvature,head height,head to tuberosity height, articular surface arc,canal width of plane of surgical neck,canal width of 20mm distal of the plane of surgical neck,canal width of 40mm distal of the plane of surgical neck,canal width of 60mm distal of the plane of surgical neck,canal width of 80mm distal of the plane of surgical neck,canal width of length of the mesio 130mm of humerus,flare variation(FV1,FV2,FV3,FV4,FV5),total length of longitudinal axis and length of mesio-humerus cylinder.The parameters of glenoid included inclination angle, retroversion angle,maximum supero-inferior height,supero-inferior radius of curvature, maximum antero-posterior width,antero-posterior radius of curvature,glenoid depth, depth of cancellous bone and width of cancellous bone.There were 64 parameters of humerus,21 parameters of glenoid and 4 parameters of glenohumeral relationship.All the parameters were processed statistically with soft ware SPSS 10.0.Results1.Paired-samples t test of all the humeral parameters at coronal and sagittal views indicated that there was significant difference among articular surface diameter at coronal view,radius of curvature at coronal view and total length of longitudinal axis measured with VRT and thick MPR(P＜0.05).But there was no significant difference for the other ten parameters measured with VRT and thick MPR(P＞0.05).ANOVA of the humeral parameters at axial view indicated that there was significant difference among the head heights of dry humerus measured with thin MPR,thick MPR and VRT(P＜0.05).While there was no significant difference for the other four parameters measured with thin MPR, thick MPR and VRT(P＞0.05).Independent-samples t test of all the humeral parameters showed that there was significant difference among articular surface diameter measured with thick MPR at axial view,head height measured with VRT at axial view,head height measured with VRT at coronal view,head height measured with VRT at sagittal view, articular surface diameter measured with VRT at sagittal view,radius of curvature measured with VRT at sagittal view,articular surface arc measured with VRT at coronal view,articular surface arc measured with VRT at sagittal view,head height measured with thick MPR at sagittal view,head to tuberosity height measured with thick MPR at coronal view,articular surface arc measured with thick MPR at sagittal view,canal width of 60mm distal of the plane of surgical neck measured with thick MPR at coronal view,canal width of plane of surgical neck measured with thick MPR at sagittal view and FV1 measured with thick MPR at sagittal view(P＜0.05),with no significant difference among the rest parameters(P＞0.05).Compared with means of all the parameters,the humeral parameters measured by MPR at coronal view exceeded those at sagittal view except that articular surface arc at coronal view was smaller than the parameter at sagittal view,and FV5 at coronal view and sagittal view was equal.The humeral parameters measured with VRT at coronal view exceeded ones at sagittal view except that articular surface arc at coronal view was smaller than the one at sagittal view.Articular surface diameter and radius of curvature at axial view were smaller than those at coronal view,articular surface arc at axial view was larger than the one at the other two views.Every parameter existed variation to some extent,for instance,the retroversion angle of humeral head ranged from 3.3°to 57.0°.Humeral canal width of all planes at coronal view exceeded those at sagittal view,but resembled at the plane of length of the mesio 130mm of humerus.FV1 was the most obvious,followed by FV2,that was similar from FV3 to FV5 at coronal view and sagittal view.The correlations were different among some humeral parameters done with correlation analysis.2.Paired-samples t test of all the glenoid parameters measured with thin MPR and thick MPR indicated that there was no significant difference among antero-posterior radius of curvature,retroversion angle,glenoid depth at axial view and depth of cancellous bone (P＞0.05),and significant difference among maximum supero-inferior height, supero-inferior radius of curvature,maximum antero-posterior width,glenoid depth at coronal view and width of cancellous bone(P＜0.05).Independent-samples t test of all the glenoid parameters showed that there was significant difference between antero-posterior radius of curvature,maximum antero-posterior width measured with thin MPR, retroversion angle,Supero-inferior radius of curvature,inclination angle,glenoid depth measured with thick MPR at coronal view and width of cancellous bone measured with thin MPR at coronal view(P＜0.05).Compared with mean of all the glenoid parameters, antero-posterior radius of curvature,maximum antero-posterior width measured with thin MPR,supero-inferior radius of curvature and inclination angle of dry scapula were smaller than the ones of wet cadaver scapula,but glenoid depth measured with thick MPR at coronal view and width of cancellous bone measured with thin MPR of dry scapula exceeded those of wet cadaver scapula.Retroversion angle of glenoid ranged from -3.0°/-2.7°to -0.4°/-0.34°between two kinds of scapula.It indicated that the glenoid of wet cadaver scapula was obvious at posterior tilt.The correlations were different among some glenoid parameters done with correlation analysis.3.The statistical analysis had obtained the means,standard deviation,maximum value and minimum value of all parameters.The value of every parameter was compared with overseas and domestic results.Our results indicated that the total length of longitudinal axis of humerus,radius of curvature of humerus at coronal view,head height of humerus at coronal view,medial offset of humeral head,head to tuberosity height,articular surface arc of humerus at coronal view and conformity index were smaller compared with the westerners'.On the contrary,posterior offset of humeral head,inclination angle of humeral head,inclination angle of glenoid and supero-inferior radius of curvature of glenoid were larger than the westerners'.Conclusions1.The method of measuring bone geometry of the glenohumeral joint with postprocessing technique of MSCT is established initially in the experiment.Multiplanner reformation(MPR) and volume rendering technique(VRT) of MSCT are useful postprocessing technique for measurements,VRT should be recommended for humeral data measurement.2.There are some variations at different extent among the Chinese parameters related with the design of shoulder prosthesis and certain obvious discrepancy compared with the westerners',so the size and specification of shoulder prosthesis should be diversified. |
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