ABSTRACT
Malalignment causes abnormal forces that may lead to loosening after knee replacement. Whether a computer-assisted technique can improve the precision of implant positioning guaranteeing good long-term results in total knee arthroplasty, this is a matter of discussion. The authors evaluate the alignment accuracy of 20 primary total knee arthroplasties, performed using an image-free computer navigation systems, with standardized CT protocol and three-dimensional digital model reconstruction. The results of this study demonstrate that the image-free navigation system is able to improve accuracy in axial limb alignment and positioning of the components in the majority of cases; moreover, the difference between the mean mechanical axis value of the navigation system (179.7° ± 1.7°) and the median mean value obtained during the post-operative evaluation (180.3° ± 1.9°) is not statistically significant (P = 0.28).
Subject(s)
Arthroplasty, Replacement, Knee , Imaging, Three-Dimensional , Osteoarthritis, Knee/surgery , Surgery, Computer-Assisted , Aged , Aged, 80 and over , Algorithms , Arthritis, Rheumatoid/surgery , Arthroplasty, Replacement, Knee/methods , Female , Humans , Male , Middle Aged , Osteoarthritis, Knee/etiology , Retrospective Studies , Surgery, Computer-Assisted/methods , Tomography, X-Ray Computed , Treatment OutcomeABSTRACT
The standardized femur is the computer aided design (CAD) solid model of a synthetic human femur, commonly used in experiments in vitro, available in the public domain through the International Society of Biomechanics Finite Element Mesh Repository. Currently used by hundreds of researchers, it was made available to simplify the experimental cross-validation of numerical studies as well as their replication by other researchers. One aspect that the standardized femur left uncovered is the definition of muscles and ligaments. In particular, for a variety of simulations it would be extremely useful to map on to the femoral surface the insertion of the principal muscles. The aim of the present study was to create a new solid model, called the muscle standardized femur, where the femoral insertion of each muscle is mapped on to the surface of the femur. Published data on muscle insertion morphometry were registered to the model by applying an affine scaling defined on bone landmarks. Good agreement was found with another similar study in which only the insertion centres were defined. The new model will be made available in the public domain for no-profit uses. When combined with published data on the direction and intensity of muscular forces this model is expected to make a useful contribution to the steadily growing library of models and data sets made available to the biomechanical community.
Subject(s)
Anatomy, Cross-Sectional/standards , Computer-Aided Design/standards , Femur/anatomy & histology , Models, Anatomic , Muscle, Skeletal/anatomy & histology , Tendons/anatomy & histology , Anatomy, Cross-Sectional/methods , Biomechanical Phenomena , Cadaver , Databases, Factual , Finite Element Analysis/standards , Humans , Reference Standards , Reproducibility of Results , Sensitivity and Specificity , Thigh/anatomy & histologyABSTRACT
Giant cell arteritis (GCA) or temporal arteritis is an entity of unknown aetiology and uncertain autonomy for the close relationship with polymyalgia rheumatica (PMR). This work describes four patients with GCA alone. All patients had clinical and laboratoristic evidence of the disease and were treated with steroids. The distribution of HLA antigens showed an increased occurrence of DR4 and B8 antigens. Unfortunately, the small number of patients and the short period of observation don't allow to prove the exact nature of the link between GCA and PMR.
