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Biomedical subjects

P Griss

Publications and source records attributed to P Griss.

At least 73 records · Page 4Linked to original sources
PubMed1982

The influence of fine surface structures on the osseo-integration of implants.

The availability of inert materials like dense, pure Al2O3-ceramic or titanium allows the study of purely biomechanical influences of surface modulations or lacune on the osseo-integration of implants at different locations of the skeleton. The discovery of the "load-line-shadow" phenomenon in lacune of dental implants and the observation of the same effect in the grooves of hip sockets (Lindenhof type) indicate the general validity of the rules controlling the remodelling ability of bony tissue. Their application to the problems concerned with load transmission via surfaces which are mainly loaded by shear can contribute to achieve a well defined anchorage of implants.

Aluminum Oxide↗
PubMed1981

The operative treatment of congenital scoliosis. A review of 26 cases.

The experiences with 26 personal cases of congenital scolioses operated on between 1970 and 1980 are presented. The average postoperative follow-up is 3 1/2 years. The natural complexity of spine malformations with predominant lateral deviation is discussed and demonstrated. Accordingly, a number of varying anterior and posterior operative methods were used in the individual case. The scope of operative methods used in this series is outlined. Characteristic patterns of spine malformation and the individual sequence of operative procedures applied are explained and documented by case demonstrations. The overall correction of all curves operated on was 38%. When cases chosen for combined staged anterior and posterior surgery were looked at separately the percentage of average correction rose to 51%.

Adolescent↗
PubMed1981

Five years experience with ceramic-metal-composite hip endoprostheses. I. clinical evaluation.

Clinical experience with 130 endoprostheses, entirely made of ceramic, having an average 5 year follow-up is reported. Excellent to sufficient results were seen in 84% of all cases. A number of particular matters of interest (operative technique, radiological morphology of the bone/ceramic bone interface etc.) are discussed in detail. Complications (loosening of components: 2%; component fracture: 6%, wear phenomena etc.) are described and documented including histological observations from capsular tissue of total ceramic hip joints. The whole system has basically stood the test, during the implantation period, modifications to improve the function of the system will be described in another publication.

Adult↗
PubMed1981

Five years experience with ceramic-metal-composite hip endoprostheses. II. Mechanical evaluations and improvements.

The results of the complete and detailed clinical evaluation are compared with the original design criteria. It is shown that most of them stood the test. Those aspects which did not meet the expectations are discussed in detail: The occurrence of very little and biologically tolerable wear during the initial running-in period will be further reduced by a considerable improvement of the material properties. The few cases of severe wear had been associated with clinically exceptional situations, the analysis of which allows for suggestions to avoid such situations. The material improvements and all other steps taken to increase the safety margin considerably against fractures of the ceramic ball are described in detail. In addition, the attention is paid to some necessary clinical precautions.

Aluminum Oxide↗
PubMed1981

The effects of mechanical factors on bio-compatibility tests.

Evaluation of materials for bone and joint replacement has led to contradictory results in a number of cases: some researchers have reported the formation of good load-bearing bone structures along the surface of a particular material, e.g. dense, high strength Al2O3-ceramics, others found the same material encapsulated by soft tissue. Considering the results of various animal experiments and the evaluation of clinical follow-up studies, it can be shown that many of these conflicting observations are due to different biomechanical conditions at the site of examination. Failure to consider the local load situation at the interface between the implanted specimen and the bone tissue can lead to misleading statements about the possible applications of a material.

Animals↗
PubMed1981

Comparative histocompatibility testing of seven calcium phosphate ceramics.

Five hydroxyapatite and two tricalcium phosphate ceramics were implanted in rat femora for one to six months. They were compared with each other in regard to biocompatibility and bone induction. After one month bone had grown directly on to the surface of all implants. After six months the on-growth of bone had increased with the exception of two dense HA materials. In these materials some bio-degradation had occurred with subsequent formation of a wide macrophage interlayer. Bio-degradation and biocompatibility of calcium phosphate ceramics seem to depend not only on density but also on other factors. Induction of bone could not be observed in soft tissue environment.

Animals↗
PubMed1981

[Early results of operative treatment of scoliosis using the anterior derotation spondylodesis technique (VDS-Zielke) (author's transl)].

The paper presents early results of 25 surgical procedures for scoliosis using the instruments and implants of the anterior derotation spondylodesis (VDS-Zielke). The series included 10 dorsal, 3 dorso-lumbar and 12 lumbar curves, whereby up to 8 vertebral bodies were fused. The average postop. follow-up time was 25 months (8--45 months). The average degree of correction was 51 p.c. Emphasis is layed on the fact that aetiology and severity of the scoliotic curves was extremely heterogeneous. Besides excellent corrective potentials of the VDS for scoliosis, this technique offers possibilities for correction of cyphosis or lordosis as well. The results are described and documented in detail. The author puts much emphasis in describing special techniques for correcting lordosis or cyphosis as well as scoliosis in the same patient. The analysis of the results presented shows good indications for VDS in dorso-lumbar and lumbar scoliosis, congenital scoliosis of the dorso-lumbar area and thoracic lordo-scoliosis. For the indications outlined the possibilities of the VDS are superior to any other operative technique for scoliosis (Dwyer, Harrington). The rate of complications can be kept low through good selection of cases, excellent surgical technique and postoperative intensive care.

Adolescent↗
PubMed1980

[Modification of sagittal osteotomy of the patella as treatment of excentric chondromalacia or retropatellar arthrosis. Preliminary communication (author's transl)].

The author presents a modification of Morscher's sagittal osteotomy of the patella especially for the treatment of excentric chondromalacia. Congruity of the joint spaces in this modification is achieved through removal of an anteriorly based bone wedge from the patella after sagittal wedge osteotomy allowing the lifting of one or the other patellar facet. This osteotomy is indicated in all cases of unilateral chondromalacia or arthrosis with narrowing of the two joint spaces viewed on tangential patello-femoral X-rays. Following the ideas of Pauwels and Maquet, restoration of a wide joint space and reduction of local excessive stress result in reparative mechanisms of the cartilage involved. The to date preliminary clinical results in 5 cases (1 year max. follow-up) are encouraging.

Adult↗
PubMed1979

Direct anchorage of Al2O3-ceramic hip components: three years of clinical experience and results of further animal studies.

The biocompatibility of high-purity dense Al2O3-ceramics had been shown to open the possibility of direct cement-free anchorage of joint endoprostheses. Three years of clinical experience with ceramic-metal composite total hip prostheses confirm the biomechanical design criteria used for the acetabular components. They also allow for additional conclusions regarding the reaction of bone tissue towards a bioinert implant. Further research activities are directed towards a solution for biomechanically stable anchorage of the femoral component of hip prostheses.

Aged↗
PubMed1978

[A new technique for socket implantation into dysplastic acetabula (author's transl)].

This report presents a new technique of socket implantation into the dysplastic acetabulum. A major part of the resected femoral head serves as the so-called intra acetabular femoral head graft and is screwed into the lateral part of the original acetabulum. By this technique it is possible to achieve a complete bony reconstruction of the dysplastic acetabulum into which a square shaped small ceramic socket can be easily implanted using few especially designed instruments. After the description of the operative technique this report presents the clinical results of this procedure based on 11 personal cases. Finally the technical, biomechanical and biological advantages of this implantation technique are discussed in view of other similar methods described recently.

Acetabulum↗
PubMed1978

[Comparative experimental investigations with bioglass (L. L. Hench) and Al2O3-ceramic coated with mod. bioglass. II. Results of experiments with loaded implants (author's transl)].

This report is based on 4 comparative experimental series is sheep using a cementfree total hip replacement model. Basically a smooth stem design was compared to a step stem design for biomechanical interlocking anchorage. Both designs were implanted as pure high density Al2O3-ceramic components and as Al2O3-ceramic parts coated with Bioglass or Bioglass-ceramic (post op. follow up 13 months, 17 animals). None of the 4 stem modifications showed a tendency for permanent stabilisation or bonding in bone. Besides insufficient bonding of the glass coatings to the substrate and apparent biodegradability of the bioglass coatings in the body, insufficient biomechanical knowledge of endosteal direct anchorage of prosthetic devices is the main reason for failure in these experiments. An exclusive biochemical way of anchoring prosthetic parts in the marrow cavity is rejected. The results presented are discussed in the light of the recent literature.

Aluminum Oxide↗
PubMed1978

[The relevance of histological results for the evaluation of materials for bone replacement (author's transl)].

Different groups have observed and reported deviating tissue reactions for the same material for bone replacement: for the "bioinert" Al2O3-ceramic close bone contact is mentioned, others report about a soft tissue layer adjacent to the implant; for the "bioactive" glass ceramic interfaces capable to transmit considerable shear forces are described, others found no interface bonding.--The analysis of the results of animal experiments and the evaluation of clinical follow-up studies show that these discrepancies had been caused by the differences of the biomechanical situations in the examined interfaces. It is pointed out that the negligence or not mentioning of the load pattern at the site of examination can lead to misinterpretations about the possibilities and limits of applicability of biomaterials.

Aluminum Oxide↗
PubMed1978

[Results of corrective surgery in juvenile cyphosis (scheuermann's disease) using Harrington's compressive rods (author's transl)].

The authors present the results of 20 corrective procedures for juvenile cyphosis using Harrington compressive rods and Hibbs spondylodesis. 16 procedures date back more than one year (average 3 years, 4 months). 10 cases of pure dorsal cyphosis. The pre-operative Cobb-angles for cyphosis averaged 52 degrees, postoperatively an average of 24 degrees was measured. This reflects a 57 p.c. average immediate correction (41 p.c. for pure dorsal cyphosis, 71 p.c. for dorso-lumbar cyphosis) following surgery nearly all cases showed a significant loss of correction (average 43 p.c., dorsal 37 p.c., dorso-lumbar 49 p.c.). Three main reasons for this loss of correction are discussed and documented in detail. 1. Mal-centered and too short a length of spondylodesis; 2. insufficient corrective growth of wedge shaped vertebral bodies post surgery and 3. frequent lumbar decompensation into total round back deformity of the pure thoracic spondylodesis. The following changes in procedure to solve the problem of loss of correction are proposed. 1. Combined posterior and anterior fusions and 2. upper lumbar dorsal fusion together with extended thoracic spondylodesis. The changing indication is discussed. The main but not fatal complication was postoperative wound infection (15 p.c.).

Adolescent↗
PubMed1977

[Comparative experimental investigations with bioglass (L. L. Hench), Al2O3-ceramic and Al2O3-ceramic coated with a mod. Bioglass. I. Results of experiments under non-loaded conditions (author's transl)].

This report deals with comparative results obtained with unloaded intra-osseous implants of bioglass (L. L. Hench), Al2O3-ceramic and Al2O3-ceramic coated with a mod. bioglass. Al2O3-ceramic and bone form a direct bony interface without fibrous tissue interposition, this resulting in a pure mechanic fixation of the implant through frictional forces of the surface roughed ceramic. Pure bioglass (45S5) and bone form a unique persisting direct interface by means of physico-chemical or biochemical phaenomena stabilizing the implant. Interface stability seams to be higher than the fatique strenth of the glass itself. This interface is developed as a consequence of solubility of some of the glass constituents within a surface layer of up to 200 microns, running parallel with a reduction of strength of this surface glass layer. The boronoxide containing bioglass, flame-sprayed onto Al2O3-ceramic samples seams to be less soluble and therefore seams to have lesser bonding capability to bone. The stability of the interface bioglass coating-Al2O3-ceramic was low.

Aluminum↗