RESUMO
A method is described which provides standardised reproducible radiographic images of the lower limb. Anteroposterior and lateral radiographs are digitised and processed by computer to provide graphic/numeric displays of angles and linear measurements, relating the centre points of the hip, knee, and ankle. Two cases illustrate how surgical planning is facilitated when standardised data are available. These data confirm the close relationship between postoperative limb alignment and positioning of prosthetic elements.
Assuntos
Artrite Infecciosa/diagnóstico por imagem , Articulação do Joelho/diagnóstico por imagem , Prótese do Joelho , Ortopedia/métodos , Osteoartrite/diagnóstico por imagem , Idoso , Artrite Infecciosa/etiologia , Artrite Infecciosa/cirurgia , Doença de Crohn/complicações , Fraturas do Fêmur/complicações , Fraturas não Consolidadas/complicações , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Osteoartrite/etiologia , Osteoartrite/cirurgia , Postura , Radiografia , Reprodutibilidade dos TestesRESUMO
Clinical results with elbow prostheses have been disappointing. A detailed knowledge of elbow joint geometry and mechanics is necessary to improve prosthetic design. In this study, the humeroulnar articulation of four human cadaver elbows was examined using surface analytic methods. In this article, the location of the transverse axis of elbow flexion-extension is suggested in relation to well-defined landmarks, the medial and lateral epicondyles, and subsequently to the line connecting their most lateral points--the transepicondylar line. The geometry of the structures responsible for the carrying angle is discussed, as is the extent of cartilage-covered bearing areas of the lower humerus and upper ulna. Implications pertaining to prosthetic design and surgical technique resulting from this study are discussed.
Assuntos
Articulação do Cotovelo/anatomia & histologia , Cartilagem Articular/anatomia & histologia , Articulação do Cotovelo/fisiologia , Humanos , Úmero/anatomia & histologia , Matemática , Movimento , Ulna/anatomia & histologiaRESUMO
Complex kinematics, anatomical features, and load distribution have contributed to the poor function of constrained and semiconstrained cemented arthroplasties of the elbow. Resurfacing by porous-coated components has the potential, by reproduction of normal joint geometry and restoration of ligament balance, to re-create relatively normal kinematics and load-bearing and provide relief of pain. A method was developed to provide information on the geometry of the lower humeral joint surface and olecranon fossa. The information gained was used to design components to resurface the trochlea, capitellum, and olecranon fossa. A technique was also developed to remove a minimal amount of subchondral bone from the ulna and humerus in a precisely directed fashion for exact fit of the porous-coated components.
Assuntos
Articulação do Cotovelo/cirurgia , Prótese Articular , Articulação do Cotovelo/diagnóstico por imagem , Feminino , Humanos , Úmero/cirurgia , Masculino , Métodos , Desenho de Prótese , Radiografia , Rádio (Anatomia)/cirurgia , Propriedades de Superfície , Ulna/cirurgiaRESUMO
The sizing and dimensioning of a new unconstrained elbow prosthesis makes use of a geometric axis for humeral articulating surface definition, an axis which is precisely positioned with respect to extra-articular anatomical landmarks. The geometry of the joint was determined by a slicing and digitization technique. It was found that for the humerus an axisymmetric surface is evident and that there exists a centroidal axis which is mostly linear except for a portion at the posterior lateral flange of the trochlea. Sizing studies were carried out on dry bone anatomical specimens and, using a standardized X-ray technique, on the elbows of volunteer subjects. Seven dimensions were chosen for statistical analysis of the joint. A multi-variate normal distribution model, using only the first principal component was found to account for 70% of the variance; components 2 and 3 explained a further 19%. From this analysis, one series of three and five sizes of prosthetic dimensions were established for 95% overall coverage of population.
