PubMed Health⌕ Search

Biomedical subjects

J Richolt

Publications and source records attributed to J Richolt.

7 recordsLinked to original sources
PubMed2006

[Historical development of arthrodesis of pes cavus].

In contrast to the present, the diagnosis and treatment of pes cavus was a major subject of research at the beginning of last century. This was due to the high incidence of certain neurological disorders (poliomyelitis, myelodysplasia) which led to the development of this foot deformity. Advances in anaesthetic technique and the establishment of antisepsis contributed largely to the development of the surgical treatment of pes cavus. Ladislaus Leo Freiherr von Lesser performed the first surgically induced ankylosis of the ankle by denuding the joint surfaces of cartilage followed by fixation with a metal nail. This procedure was then introduced as arthrodesis; a word derived from the Greek meaning "binding of the joint". Numerous methods and modifications of arthrodesis have been developed for the correction of foot deformities. With increasing knowledge of the pathogenesis of pes cavus, soft tissue and tendon transfer procedures were added to the surgical treatment. Today, the philosophy of arthrodesis in the treatment of foot deformity is the same, but the development of fixation techniques and implant materials could improve postoperative care and outcome.

Arthrodesis↗
PubMed2005

[Five-year results following autogenous osteochondral transplantation to the femoral head].

The rationale for autogenous osteochondral grafting into necrotic areas of the femoral head is to provide hyaline cartilage for areas of main articular contact pressure. The aim of this study was to present our results of autogenous osteochondral grafting to the femoral head in the treatment of avascular necrosis. The mean follow-up of the five patients was 57 months following autogenous osteochondral grafting to the femoral head using DBCS (diamond bone-cutting system). The number of transplanted cylinders varied between one and three, and the diameter of the cylindrical transplants between 9 and 13 mm. Results were unsatisfactory in four of five hips and these underwent total hip replacement a mean of 49 months following DBCS of the hip. In our hands, osteochondral grafting to the femoral head using DBCS had proven technically possible in restoring the articular surface of the femoral head; however, this operation was associated with unsatisfactory results in four of five cases.

Adult↗
PubMed2004

[Acetabular shape and cementless cups. Comparison of osteoarthritic hips and implant design].

The anatomy of the hip must be taken into account in order to ensure primary stability of cementless acetabular implants. In this study we analyzed the shapes of osteoarthritic acetabula and compared these to normal non-degenerative acetabula and to pressfit implants. We measured 92 acetabula with osteoarthritic deformations and 35 non-degenerative acetabula. Bone tissue samples from 50 osteoarthritic acetabula were microradiographically analyzed. Furthermore, the size of the entrance plane of 37 pressfit cups was determined. The craniocaudal and ventrodorsal diameters of osteoarthritic acetabula correlate strongly ( r=0.87). In craniocaudal direction, the acetabular diameter correlates significantly to both the radius of the lunate surface ( r=0.42) and the acetabular base ( r=0.54). Osteoarthritic acetabula have a deeper shape as degeneration increases and the entrance plane becomes significantly more circular ( p<0.05). When comparing osteoarthritic and non-arthrotic acetabula, the following values differ significantly (p<0.05): craniocaudal radius of the acetabular base, craniocaudal and ventrodorsal radius of the lunate surface, and ventrodorsal divergence between lunate surface and acetabular base. To reconstruct an acetabular offset which concurs with central points of the femoral head and the radius of the lunate surface, the level of the insert's entrance plane must be outside the entrance planes of the cup and acetabulum. The rims of hemispheric cups need to be trimmed to prevent these cups from extending beyond the acetabular rim.

Acetabulum↗
PubMed2004

[Cement-free hip cups. Current status].

Important criteria for stable cup fixation are the type of anchor system and stabilizers,cup form and the material and surface structure. Different fixation systems are manifest in pressfit and threaded cups. Pressfit implants are oversized and lead to equatorial jamming. For additional fixation, and to improve stability, screws, pegs, rings, fins, spikes or hollow cylinders are used. In threaded cups, thread geometry is decisive for the cup's performance during the screw-in process and positioning. The hemispheric shape of the cups requires less bone resection and the position of the implant can be arbitrarily selected. The conical shape guarantees high tilting stability. Most implants are made of pure titanium or a titanium-aluminum alloy. A rough surface area - produced by corundum blasting, titanium-plasma spray, titanium balls, nets or other grid designs - is essential for osseointegration. The results of second generation pressfit and threaded cups with 10 year survival rates of 93-100% are persuasive.

Acetabulum↗
PubMed2001

[Occipitocervical fusion in rheumatoid arthritis].

A case of spontaneous occipitocervical fusion is discussed. The authors believe that fusion at the occipitocervical junction will occasionally occur in rheumatoid arthritis in the adult population. As a result of fusion, the dens axis is unable to exert compression on the spinal cord with increased neck flexion.

Aged↗
PubMed2000

Affine adaptive filtering of CT data.

A novel method for resampling and enhancing image data using multidimensional adaptive filters is presented. The underlying issue that this paper addresses is segmentation of image structures that are close in size to the voxel geometry. Adaptive filtering is used to reduce both the effects of partial volume averaging by resampling the data to a lattice with higher sample density and to reduce the image noise level. Resampling is achieved by constructing filter sets that have subpixel offsets relative to the original sampling lattice. The filters are also frequency corrected for ansisotropic voxel dimensions. The shift and the voxel dimensions are described by an affine transform and provides a model for tuning the filter frequency functions. The method has been evaluated on CT data where the voxels are in general non cubic. The in-plane resolution in CT image volumes is often higher by a factor of 3-10 than the through-plane resolution. The method clearly shows an improvement over conventional resampling techniques such as cubic spline interpolation and sinc interpolation.

Humans↗