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Biomedical subjects

H Plenk

Publications and source records attributed to H Plenk.

At least 73 records · Page 4Linked to original sources
PubMed1987

Survival analysis of an uncemented ceramic acetabular component in total hip replacement.

Follow-up examinations of 67 implants of cement-free ceramic sockets show the need for an exact definition of failure, to warrant comparable evaluations of results. Statistical survival analysis offers the possibility of presenting both the incidence of failures and the dates of their occurrence. If only revision surgery with removal of the socket is considered to be a failure, our material shows the "survival quota" of the ceramic socket after 8 years to be 96.7% +/- 2.2%. If radiological signs of loosening are included in the evaluation of failures, the "survival quota" of the stable implants is reduced to 81.9% +/- 6.9%.

Acetabulum↗
PubMed1987

[Bone fixation of tumor endoprostheses with cast-on spherules of a cobalt-base alloy].

Special tumor endoprostheses manufactured from cobalt-base alloy with cast-on globules upon the intramedullary shaft and two paracortical flanges for screw fixation can be stabilized at the ends of long bones without using bone cement. Three such implants, retrieved in clinically stable condition after 3 months (proximal tibia), 5 months (distal humerus), and 13 months (distal femur), were investigated microscopically: new bone was found immediately adjacent to the porous surface structures and the fixation screws in many areas. The contribution of bone fragments originating from the preparation of the implant bed to this bone reaction was extremely slight. On the other hand, fibrous tissue layers and a foreign body reaction were found on the remaining surfaces, which may have been related to the compatibility of the implant material and must therefore be regarded as detrimental for the long-term prognosis concerning the fixation of such implants.

Bone Neoplasms↗
PubMed1986

[Scalpel and CO2 laser in the animal experiment. A comparative study of inoculation tumors of the mouse].

The study hereby submitted has been designed to show whether there are any differences between using a conventional knife or a CO2-laser when excising and grafting tumors in animal experiments. The animals were C57Bl/6 mice, the tumor was the Lewis lung carcinoma. Eight days after tumor inoculation into the subcutaneous layer of the back, 213 mice were treated by tumor excision either with a conventional knife or a CO2-laser. 86 excised tumors were cut and the tumor surface was swabbed into the subcutaneous layer on the nape of 86 tumor-free mice. Survival times of the laser-operated animals were insignificantly longer. However, small tumors showed markedly longer survival times. The interval without recurrence was longer for all tumor sizes when the laser was used (p less than 0.005). The laser method yielded lower growth rates when the tumor surface was swabbed into tumor-free mice (p less than 0.0001). Histological and cytological tests of the laser-excised and -swabbed specimen demonstrated a high rate of cell destruction. Therefore, the CO2-laser seems to have some importance in cases where the incision is made close to the tumor or where the tumor surface may be lesioned.

Animals↗
PubMed1986

Comparative study of conventional scalpel and CO2-laser in experimental tumor surgery.

The study hereby submitted has been designed to show whether there are any differences between using a conventional knife or a CO2-laser when excising and grafting tumors in animal experiments. The animals were C57B1/6 mice, the tumor was the Lewis lung carcinoma. Eight days after tumor inoculation into the s.c. layer of the back, 213 mice were treated by tumor excision either with a conventional knife or a CO2-laser. Eighty-six excised tumors were cut, and the tumor surface was swabbed into the s.c. layer on the nape of 86 tumor-free mice. Survival times of the laser-operated animals were insignificantly longer. However, small tumors showed markedly longer survival times. The interval without recurrence was longer for all tumor sizes when the laser was used (P less than 0.005). The laser method yielded lower growth rates when the tumor surface was swabbed into tumor-free mice (P less than 0.0001). Histological and cytologic tests of the laser-excised and- swabbed specimen demonstrated a high rate of cell destruction. Therefore, the CO2-laser seems to have some significance in cases where the incision is made close to the tumor or where tumor surfaces may be lesioned.

Animals↗
PubMed1986

[Healing of chondral fragments].

Basing on encouraging results with the fixation of pure articular cartilage with the fibrin sealant in animal experiments, pure cartilage fragments were replanted in human patients using fibrin sealant. From individual cases biopsies could be taken from macroscopically not well healed areas during arthroscopic examination. The histological results from these cases are presented together with overall clinical experiences. Six weeks after operation one side of the graft showed no union with the subchondral bone and was also separated from the cartilage bed. However, after three and six months, the grafted cartilage had fused with subchondral bone, but pannus-like tissue was covering the surface and filling the cleft at the border to the bed. After one and five years, complete fusion with the subchondral bone and the surrounding cartilage can be demonstrated. There is always covering pannus at the larger observation times. In the majority of the 48 cases treated so far excellent clinical results were obtained, enabling the patients to take up their sporting activities again.

Adolescent↗
PubMed1986

Fibrin sealant in bone transplantation. No effects on blood flow and bone formation in dogs.

To study bone formation and regional blood flow following the use of fibrin sealant in autologous cancellous bone transplantation, a dog model was developed. In 18 dogs, a standardized defect in both tibiae was filled with an autologous iliac crest graft. On one side, the bone chips were mixed with fibrin sealant while the other side served as control. After 1, 2 and 3 weeks the blood flow of the transplant was calculated and the new bone formed evaluated histomorphometrically. Generally, the highest blood flow rates and most intensive new bone formation were observed at 2 weeks postoperatively. Fibrin sealant did not alter blood flow or new bone formation, but a tendency to diminished new bone formation was found in some grafts. Our study does not support the application of fibrin sealant in ordinary cancellous bone grafting.

Animals↗
PubMed1985

Experimental mechanical and histologic evaluation of the Kennedy ligament augmentation device.

Reconstruction of the knee with a chronic injury to the anterior cruciate ligament is an unsolved problem. Biologic graft substitutes have failed to maintain knee stability in the longer postreconstruction intervals. In an attempt to overcome the limitations in graft performance, synthetic materials have been proposed to augment the biologic tissue. In this study, a 6-mm polypropylene braid Ligament Augmentation Device (LAD) possessing a tensile strength of 1500 N and excellent fatigue and creep properties was investigated as an adjunct to the MacIntosh/Marshall Over-the-Top repair. A two-year animal study of 54 adult goats was conducted in which experimental ACL defects were created and reconstructed with a transplant consisting of a portion of the rectus femoris tendon, prepatellar tissue, and the central one-third of the patellar tendon. The goats were equally divided between nonaugmented and LAD-augmented groups and sacrificed at three, six, 12, and 24 months after surgery. Mechanically, the augmented transplants were substantially stronger at the time of initial implantation (364N versus 26N) and again at two years (841N versus 528N). Intermediate times did not demonstrate a difference in strength. Histologically, the augmented transplants consisted of a loosely organized fibrous capsule surrounding the LAD. At 24 months, "insertion fibers" were noted to provide continuity between the fibrous tissue and bone on both the tibia and femur.

Animals↗
PubMed1983

[Human calcitonin in the treatment of symptomatic Paget's disease].

We evaluated the effect of a 6 months trial with synthetic human calcitonin in 10 symptomatic patients with polyosseous Paget's disease of bone. All patients reported a distinct clinical improvement which correlated with a significant decrease of alkaline phosphatase in the plasma and hydroxyproline and calcium excretion in the urine. Though no changes in skeletal x-rays were observed, the bone lesions showed a significant decrease of activity in tho bone scintigrams. Histologically there was a marked decrease of bone turn-over calcitonin therapy. No patient revealed the formation of autoantibodies against exogenous calcitonin after treatment.

Aged↗
PubMed1982

Evidence for negative correlation between quantitative histological studies and microradiography of iliac crest bone and forearm osteodensitometry in elderly women with osteoporosis.

Quantitative histomorphometric and microradiographic analysis of iliac crest bone biopsy specimens of 10 unselected and untreated postmenopausal women with osteoporosis was performed and the results were correlated with the values measured by osteodensitometry on the right forearm. No positive correlation between histomorphometry or microradiography and osteodensitometry was observed. Moreover, the data of various histomorphometric parameters and those of the bone mineral content measured by microradiography revealed a significant negative correlation when compared to the values obtained by osteodensitometry. Our results suggest, that evaluation of one skeletal site is not necessarily representative of the entire skeleton in patients with postmenopausal osteoporosis.

Aged↗
PubMed1982

Experimental investigations into the clinical significance of bone growth at viscerocranial sutures.

The development of a viscerocranial suture under physiological conditions was investigated in a total of 37 pigs and the effects of various traumas on expected sutural bone growth were observed. Different operations were carried out on one side only in the vicinity of the zygomaticotemporal suture in 18-25 day old piglets. The animals were sacrificed six months after the operation. The skulls of some of the animals were macerated and subjected to macroscopic and radiological investigation. Both zygomatic arches were removed from each of the remaining animals and used for the production of undecalcified microtome and ground sections. Intravital fluorochrome labelling was used to determine the asymmetric growth at this suture; this is interpreted as being the formation of new bone following passive expansion of the sutural region. After injury or transplantation of the periosteum and after the healing of a narrow bone defect or fracture we observed either a continuous suture from the outset or the formation of a new fissure after osseous regeneration. Similar findings were also made after the transplantation of compact rib fragments into a sutural defect without subsequent bridging of the defect. Only after the transplantation of autologous pieces of cancellous rib into an osseous defect in the sutural region was sutural ossification, accompanied by distinct deformation of the skull observed. As a clinical consequence of this it may be presumed that trauma or operation in the region of a suture has a considerable effect on the growth of the visceral cranium only if it results in premature synostosis.

Animals↗
PubMed1981

[Is the CO2 laser surgery advantageous? A morphological and experimental study (author's transl)].

The great advantages of CO2 laser surgery are the contact-less cutting and the haemostatic effect. An obliteration of blood- and lymph-vessels thus preventing tumour-cell mobilisation and metastatic spread is considered as most advantageous for tumour surgery. Basing on own morphological and experimental investigations, some of these advantages are critically discussed. The morphology of human skin incisions made by a CO2 laser is described, using light microscopy, and the wound healing process of laser incisions in the dorsal skin of rats is compared with incisions made by thermocautery and conventional scalpel. After contamination of laser and scalpel incisions with india-ink, the migration of these particles to the regional lymph-nodes was also investigated. Compared to the scalpel-incisions, the laser- and even more the thermocauter-incisions showed the well known delay in healing, due to the extensive tissue necrosis at the wound margins. This coagulation necrosis, however, was not obliterate the lymphatic drainage. It is concluded from these experiments that the use of the CO2 laser will not guarantee the prevention of metastatic spread and should mainly be recommended where the haemostatic effect is essential.

Adenofibroma↗
PubMed1981

Experience with bioceramic implants in orthopaedic surgery.

In the period from 1974 to March 1980 bioceramic endoprostheses were implanted in 155 patients. 94 patients were suffering from degenerative hip diseases and 61 had been operated for malignant bone tumours. The majority of the total endoprostheses consisted of a ceramic socket and a metal shaft prosthesis with ceramic head attached to it. Bioceramic double-cup prostheses were implanted in 19 patients without using bone cement. Following resection of malignant bone tumours, the proximal humerus and the proximal femur were replaced by special bioceramic endoprostheses. The post-operation period after implantation has reached 70 months in the case of tumour endoprostheses (average 22 months) and up to 49 months in the case of hip joint endoprostheses (average 24 months). The analysis deals exclusively with complications specific to the ceramic material. These complications are: breakage of the ceramic head (8 X), loosening of the ceramic cup (13 X) and pseudarthrosis of the cone connection in tumour endoprostheses (9 X). Abrasion particles were found in all cases which we were able to follow up histologically.

Aged↗
PubMed1981

[Hyperparathyreoidism and chronic lymphocytic leukemia (author's transl)].

A 55 year old patient with chronic lymphocytic leukemia is reported in whom hypercalcemia occurred associated with hypophosphatemia and elevated parathyroid hormone levels (C-terminal assay). Bone histology gave further evidence for hyperparathyroidism. During neck and mediastinal exploration numerous lymph nodes were exstirpated. Although pathologic parathyroid tissue could not be identified it is concluded from postoperative normalisation of calcium levels that hyperparathyroidism had been cured by surgery. The patient died the seventh postoperative day on bronchopulmonary infection. Early differential diagnostic evaluation of the rare symptom hypercalcemia in chronic lymphocytic leukemia is postulated.

Diagnosis, Differential↗
PubMed1980

[Osteopetrosis (Albers-Schönberg) (author's transl)].

Investigations of a patient with the benign adult form of osteopetrosis (Albers-Schönberg) revealed that the clinical symptoms correlated with a high bone metabolism, high calcium incorporation in bone, increased osteoclast activity and probably reactive increase of calcitonin in the blood.

Adult↗