ABSTRACT
BACKGROUND: Clinical studies demonstrate that the durable stability of the prosthesis depends on a close geometric fit between the prosthesis and femoral medullary cavity.OBJECTIVE: To study the law of the parameters of medullary canal section shape in proximal femur DESIGN: Repeated measurement observation.SETTING: Department of Orthopaedics, Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University MATERIALS: Ten femoral samples without any damage was obtained from corpse in the Staff Room of Anatomy of the Shanghai Second Medical University METHODS: The experiment was carried out in the Department of Or thopaedics, Ninth People's Hospital between January 2000 and March 2000. Section morphology of medullary cavity of proximal femur was dealt with image-processing, and conus curve fitted parameter mathematical method was proposed; and at the same time, section of medullary cavity of proximal femur of 10 patients was measured manually.MAIN OUTCOME MEASURES: Computer-aided method and manual method were applied to measure the coordination at the end of extrude and the coordinate of link joint RESULTS: 10 femoral samples entered the stage of result analysis. Com puter was used to measure the coordination of the end of extrude of the section medullary cavity of proximal femur (X,Y) and the coordination of the connection point (X,Y).There was no significant difference of the measuring results between computer-aided method and manual CONCLUSION: Computer-aided imaging-processing method not only reduces the error but also can be completed by computer automatically in measuring section morphology of medually cavity in proximal femur. It is suitable for a variety of morphology measurement.
ABSTRACT
In a hip replacement case when a standard hip stem is chosen, it is rough to select hip stems before operation, thus some stand-up standard hip stems should be prepared. The operation time is usually prolonged. In order to solve this problem, this paper presents a method to automatically select optimal standard hip stems by computers. Femoral anatomical data of a patient are acquired from X-ray films. Based on these anatomical data and a database of average cross-sections in proximal femurs, proximal femur of the patient can be reconstructed. This proximal femur model makes it possible to optimally select a standard hip stem. Theory analyses indicate that the method, presented in this paper, is practicable.
Subject(s)
Humans , Arthroplasty, Replacement, Hip , Computer-Aided Design , Hip Joint , Diagnostic Imaging , General Surgery , Hip Prosthesis , Reference Standards , RadiographyABSTRACT
BACKGROUND: Properties of cancellous bone is significant for metabolic diseases, fracture and joint retrograde diseases.OBJECTIVE: To study the biomechanical properties of cancellous bone.DESIGN: Experimental observation based on femur specimens as the single sample.SETTING: Laboratory of Orthopaedic Biomechanics Ninth Affiliated Hospital Shanghai Second Medical University.PARTICIPANTS: The study was completed in the Laboratory of Orthopaedic Biomechanics, Shanghai Ninth People's Hospital from May to July in 2001,totally 19 male cadaveric femoral heads were selected.METHODS: Totally 19 cadeveric cancellouce bone specimens(about 30years old) from the bearing area of fresh femur head were tested by compression test.MAIN OUTCOME MEASURES: Yield load limiting stress, limiting strain, energy value and elastic modulus of specimens.RESULTS: The compressive data of cancellous bone were measured, the average value of yield load was (410.64 ± 190.29) N , limiting stress was (8.69 ± 3.75) MPa, limiting strain was (10. 84 ±6.58)%, energy value was (2.54 ± 1.89)J, modulus of elasticity was (40.77 ± 32. 12)MPa, At the early time of loading, the cancellous bone showed elastic deformation, then CONCLUSION: The trial indicates that biomechanical properties lighten the pressure of external compression.
ABSTRACT
A novel method for the design of hip joint prostheses based on X-ray films is introduced. Only arcs and straight-lines form figures of hip joint prostheses. Because geometrical tolerances of manufacturing hip joint prostheses matching section are usually not strict, hip joint prostheses can be manufactured without CNC machine tool. Three hip joint prostheses for three different femurs were designed through a program which was developed by the present authors. Approximate marrow cavities of these femurs were simulated according to a standard database about femur. These models of femur marrow cavities were used to verify the hip joint prostheses designed. These hip joint prostheses designed were manufactured and implanted into femurs respectively. Experimental results indicate that the novel method for the design of hip joint prostheses is practicable.
Subject(s)
Humans , Computer-Aided Design , Hip Joint , Diagnostic Imaging , Hip Prosthesis , Prosthesis Design , Methods , Tomography, X-Ray ComputedABSTRACT
This study sought to establish a set of hip prostheses for the Chinese population and improve the design guidelines for hip prostheses. 480 cadaveric adult femora were obtained for X-ray imaging. 21 geometric parameters of femora were sampled on the anteroposterior(AP) and mediolateral(ML) views of radiograph in conjunction with computer-aided image processing technology. The curves of canal of proximal femur were fitted and made statistics. Pattern recognition was used to classify these geometric parameters. The results of classification corresponded with the 10 groups of data for design. On the basis of the numerous set of data, the results and classification would serve as means and guidelines for optimizing the design of prosthetic components and so far as custom-built hip prosthetics.
Subject(s)
Humans , Femur , Diagnostic Imaging , Hip Prosthesis , Image Processing, Computer-Assisted , Pattern Recognition, Automated , Prosthesis Design , RadiographyABSTRACT
OBJECTIVE: To explore the changes of biomechanic al properties of cortical allograft in different mechanical environments. METHODS: Cortical allograft was transplanted to each side of th e midshaft diaphyseal ulna of each one of 40 rabbits. The left transplanted allo graft underwent normal physiological load, while the right one underwent lower l oad. After animals were killed,specimens were taken for examination of bone mine ral density, bone porosity and maximal three-point-bend breaking load. RESULTS: The union strength of allograft-host bone junction wa s increased constantly; meanwhile, the internal creeping substitution led to an initial greater weakening of the cortical allograft itself and a later recovery of its strength. In comparison, the union strength of the normally loaded graft -host bone construct was significantly higher than that of the lower loaded sid e at the 8th and 16th week after transplantation. At the 16th week, there was gr eater bone strength in normally loaded graft than that in lower loaded graft. CONCLUSIONS: The internal repair can lead to initial greater we akening of cortical allograft and later gradual recovery of its strength. The ef fect of physiological load can accelerate the improvement of the biomechanical p rope rties of allograft.