| Objective:To measure the effective joint contact areas of the metacarpophalangeal joint(MPJ)during flexion and define the part of articular surface that is involved in the MPJ flexion and extension activities.To provide the basis of research for the metacarpophalangeal joint injury after treatment of articular surface defects,articular surface transplantation and artificial joint design.Methods:Ten healthy volunteers whose hands without any previous trauma or other pathological diseases were examined.All volunteers were male and using right hands,the mean age was 27 years(range,24 to 32 years),the average height was 174cm(range,171to 175cm).A movable brace is used to fix the MPJ at 0°,30°,60°and 90°.Three-dimensional computed tomography(CT)scanning was performed at 20°intervals during passive flexion from 0°to 90°with use of a CT scanner with an image slice thickness of 0.625 mm.The DICOM images data were get from CT scanning and then imported into the image processing software Mimics 17.0(1)Mark the"effective joint contact surface":in the MIMICS software interface,select the metacarpophage joint sagittal tomography image processing,measuring the MCH and proximal phalangeal base(proximal phalangeal base,PPB)between the relative points Distance,measured by the most radial side of the foot side of the layer,each layer of image in all the distance<1.5mm(refer to the relevant literature)of the articular surface part of the mark,the part of the mark is the effective joint contact part.(2)Reconstruction of the three-dimensional image of the metacarpophalangeal joint:Reconstruct the whole three-dimensional image of the articular surface of the metacarpophalangeal joint and the marker,and observe the physiological morphology of MCH and PPB respectively,and 2-5 refer to the morphological difference of MCH,While measuring the length of 2-5 metacarpal in the three-dimensional reconstructed image.(3)Measurement 2-5 refers to the side of the frontal and metacarpal in the coronal and sagittal plane of the side of the angle:respectively,marked 2-5 refers to the adjacent phalanx and metacarpal sagittal plane,measured between the two Offset angle;mark 2-5 refers to the proximal part of the phalanx and metacarpal coronal plane,measuring the lateral angle between the two.(4)To reproduce the effective contact surface at different angles on the metacarpal head,and measure the value of the area:the reconstructed image data into the 3-matic software,after a series of three-dimensional reconstruction of the metacarpal And the width of the contact area at different flexion angles and the size of the total joint area involved in the MPJ flexion and extension activities were measured at different angles.Results:1.In the process of 2-5MPJ flexion,the dorsal part of MCH articular surface is always not involved in joint activities,while the contact areas involved in joint activities from the dorsal to palm side gradually increased.When the MPJ at 90 degrees,almost all of the volar surface of the MCH articulate with the PPB.The estimated MCH contact areas at 0°,30°,60°,and 90°of the index finger respectively was 32.92±2.47mm~2,49.94±1.67mm~2,60.48±2.55mm~2,80.05±2.51mm~2;the middle finger respectively was 35.90±2.48mm~2,55.61±2.14mm~2,69.09±2.27mm~2,88.63±2.04mm~2;the ring finger respectively was31.51±1.07mm~2,48.60±2.26mm~2,57.00±2.80mm~2,74.84±1.88mm~2;the little finger respectively was 26.19±2.12mm~2,34.73±2.04mm~2,47.02±1.70mm~2,57.80±0.81mm~2.2.In the process of flexion,the longitudinal axis of the proximal part of the phalanx is not on the same plane.2-5 refers to the inflection of four fingers close together in the process of bending,is not simply a single plane of the arc movement,but involves the axial rotation and lateral offset of the complex movement,in the process of flexing,Radial offset of about 28°,supination about 4°,the middle finger near the finger to the radial side of the deviation of about 6°,supination about 8°,ring finger near the finger to the ulnar side of the deviation of about 13°,supination about 23°;little finger near the finger to the ulnar side of the deviation of about 18°,supination about 25°.3.The width of the contact region of the fingers was increased during flexion.The width of the contact region of the index finger was increased from 7.5±0.38mm to 12.04±0.41mm during flexion,the middle finger was increased from 8.30±0.49mm to 12.05±0.44mm,the ring finger was increased from 7.80±0.31mm to 11.62±0.40 mm,and the little finger was increased from7.11±0.45mm to 10.30±0.20 mm.The change of the width of the contact areas during flexion was statistically significant(P<0.05).4.The total contact areas of the MCH was the largest in the MPJ of the middle finger.There was no significant difference between the index finger and the ring finger,and the little finger was the smallest.The total contact areas were:index finger 156.12±12.13mm~2,middle finger 175.70±9.84mm~2,ring finger152.27±9.14mm~2,little finger 120.53±7.65mm~2.5.The ratio of the length of the metacarpale and the total contact areas in the 2-5 fingers is 0.42、0.36、0.37、0.43.the length of the 2-5 metacarpale are 64.58±0.86mm、63.20±1.85mm、55.37±1.49mm、52.13±1.51mm.Conclusions:During the flexion and extension of the entire MPJ,some of the articular surfaces of the MCH did not always participate in joint activity,and the effective contact of the articular surface gradually increased from the dorsal side to the palm side,and the width of the contact area gradually increased.At the same time in the 2-5 flexion process,the index finger,ring finger and little finger there is a certain degree of side angle,not a single along the respective longitudinal axis of the flexion and extension activities.The three-dimensional reconstruction technique can be used in the related research of metacarpophalangeal joint,which provides a more advanced,accurate and three-dimensional visualization method for the study of human facet joint. |
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