Biomedical subjects

W Küsswetter

Publications and source records attributed to W Küsswetter.

At least 19 recordsLinked to original sources

PubMed2003

Superior efficacy in suppression of heterotopic bone formation using fractionated irradiation of 5 x 2 Gy compared to a single dose of 7 Gy. An experimental study in rats.

Postoperative irradiation of the operative field is an established method to prevent heterotopic ossification in total hip arthroplasty. In this study two theoretical dose-equivalent regimens of radiation therapy were compared. Allogenic bone matrix was implanted in both thighs of 50 adult male Wistar rats to induce heterotopic ossification. Immediately after operation the implants of 40 animals were irradiated using a single-dose of 7 Gy or 5 fractions of 2 Gy each. Ten rats served as a controlgroup and did not undergo irradiation. Radiation therapy with 5 x 2 Gy led to a highly significantly better suppression of heterotopic ossification than irradiation with 1 x 7 Gy (p < 0.001; paired-t-test). Single-dose irradiation reduced the mean calcium contents to 138.87 +/- 22.84 micrograms Ca2+/mg implanted bone matrix; fractionated irradiation obtained a reduction to 63.35 +/- 21.16 micrograms Ca2+/mg implanted bone matrix. In thigh implants not exposed to irradiation the mean calcium content was 191.50 +/- 11.46 micrograms Ca2+/mg implanted bone matrix. Radiographically better suppression of bone formation could be documented after irradiation with 5 x 2 Gy compared to 1 x 7 Gy and non-irradiated implants. The histological aspect of the explanted specimens showed quantitatively more new bone formation in the non-irradiated controls than in both irradiation groups. In view of experimentally demonstrated better effects, as well as the reduced side effects, fractionated irradiation appears preferable.

Animals↗

PubMed2001

[Osteogenetic activity of BMP-3-coated titanium specimens of different surface texture at the orthotopic implant bed of giant rabbits].

INTRODUCTION: The successful combination of osteoinductive factors with current materials used in both endoprosthetics and implantology improves bony ingrowth and long-term stability of the chosen implants. The aim of the present experimental animal study was to clarify in what way faster bony integration can be achieved through additional BMP-3-coating of titanium test implants of different surface textures (hydroxy-apatite-coated or corundum-blasted). METHODS: Thirty of 60 cylindrical titanium test implants with a hydroxy-apatite or corundum-blasted surface were coated with 230 microg porcine, high-purified BMP-3-precipitate per implant to check their osteoinductive potential in a bioassay. In each case a BMP-3-coated and an uncoated control-device were implanted with a gap formation of 1 mm into the femoral part of the patellofemoral joint of the right and left leg of 30 adult giant rabbits. Serial saw slices of all explanted specimens were prepared, and the osseous integration of the implant and time-dependent bone neoformation were analyzed microscopically and histomorphometrically 14, 35, and 56 days after implantation. RESULTS: Coating of TiAl4V6-test devices with BMP-3 led in both groups after gap implantation to an improved osseointegration, that was histomorphological and histomorphometrical verifiable. Statistical evaluation using the t-test for matched samples showed 5 weeks after surgery a significant higher volume of new formed bone of the BMP-3-coated corundum-blasted or hydroxy-apatite-coated TiAl4V6 test devices compared to the non-coated controls of the same type (P < 0.01). Light microscopy demonstrated osseointegration without connective tissue membrane around the surface of the implants after 2, 5, and 8 weeks. Better osseointegration was achieved in the hydroxy-apatite-coated implants than in the corundum-blasted implants. CONCLUSIONS: Our results indicate that composite metal implants, as used in endoprosthetics and implantology, are suitable carriers for BMP-3 and improved fixation of the implants can be achieved.

Alloys↗

PubMed2000

Effects of single-dose versus fractionated irradiation on the suppression of heterotopic bone formation--an animal model-based follow-up study in rats.

The histological and enzymatic effects of single-dose irradiation of 7 Gray (Gy) versus fractionated irradiation of 5 x 2 Gy on the suppression of heterotopic ossification were examined over a period of 60 days in adult male Wistar rats (n = 57). The standardized osteogenesis model system in rats 19, 10, 11, 16, 19] was used for this purpose. The course of developing ossifications was documented quantitatively and qualitatively by means of quantitative computed tomography/osteodensitometry and digital luminescence radiography. Assessment of the activities of the enzymes alkaline and acid phosphatase throughout the experiment as well as characterization of the isoenzyme of alkaline phosphatase (AP) in connection with histological observations displayed a metaplasia of the ingrowing connective tissue into bone-typical cells during osteoinduction. Thus, the increase of AP is the first sign of a functional transformation of mesenchymal stem cells into chondroid bone cells. The increase in the acid phosphatase level with a maximum of activity between the 15th and 30th day (according to the respective treatment group) is highly suggestive of a remodeling process paralleling incipient chondroclast and osteoclast activity. In the animal groups undergoing irradiation, the above-mentioned increase of enzymes occurred after a delay. Furthermore, the maximum values observed were lower than those in the group not undergoing irradiation. Both findings were more manifest in the animal group which underwent 5 x 2 Gy of radiation than in the group which underwent single-dose irradiation of 7 Gy. Radiation suppresses matrix-induced osteogenesis. The histological and enzymatic course of this process was unchanged in the animals which did not undergo irradiation. However, it was quantitatively reduced and accompanied by a retardation of osteogenesis. Both effects were again reduced with fractionated irradiation of 5 x 2 Gy, which is theoretically dose-equivalent to a 1 x 7 Gy application. Histological examinations revealed damage to the migratory, proliferating mesenchymal stem cell population by irradiation doses which had relatively small effects on preosteoblasts, osteoblasts, chondroblasts and other specialized cell forms. Therefore, it may be concluded that the smaller degree of heterotopic ossification in the irradiated groups was due to damage of and a decrease in the number of mesenchymal stem cells at the implant site. Our results stress the necessity of instituting postoperative irradiation therapy as early as possible to prevent heterotopic ossification. In view of experimentally proven better effects, fractionated irradiation has to be preferred to a dose-equivalent single-dose radiation, especially considering the fewer side-effects noted with fractionated irradiation.

Acid Phosphatase↗

PubMed1999

[Effect of diclofenac on human osteoblasts and their stromal precursors in vitro in relation to arthroplasty].

INTRODUCTION: Results of animal experiments have demonstrated that the osseous integration of non-cemented prostheses can, at the very least temporarily, be impaired by the application of non-steroidal antiphlogistic agents (such as diclofenac). It is the objective of this study to examine whether there is a direct influence of diclofenac used in usual clinical dosages (3 times 50 mg daily) on bone cells and their progenitor cells which would explain the observed slow integration of the prostheses. METHODS: To investigate this, cultivated human in vitro osteoblasts and stromal bone marrow cells were incubated with increasing doses of the medications. Our study focused on the effect of diclofenac application on proliferation and functional metabolism in both cell lines. The measurable maximal plasma concentration 2 h after the application of one tablet Voltaren 50 reached 1.6 micrograms/ml. This correlated with diclofenac concentrations between 1 and 10 ml found in our experiments. The detected values were correlated to the control group (0 microgram/ml diclofenac). RESULTS: The drug effect upon osteoblasts was higher than on progenitor cells. The proliferation of in vitro stromal bone marrow cells, compared to untreated cells, was found to be decreased. We observed a decrease to 82% at a diclofenac concentration of 1 microgram/ml, Osteoblasts exhibited a decrease to 97.5% at the same concentration. The DNA synthesis increased to 118% in stromal bone marrow cells, in osteoblasts to 144%. In contrast, we detected a neglectible decrease to 92% in the collagen synthesis of osteoblasts compared to untreated cells. The synthesis of osteocalcin by osteoblasts increased to 119%. The alkaline phosphatase activity was found to be decreased to 88% in stromal bone marrow cells and increased in osteoblasts to 111%. CONCLUSION: Temporary inhibiting effects on osseous integration in non-cemented prosthesis by diclofenac could be caused by a disturbance in the anabolic bone metabolism, exhibited by an increase of osteoblastic osteocalcin expression. Osteocalcin as a known negative regulator of the osteoneogenesis is most likely inhibiting the collagen matrix deposition.

Aged↗

PubMed1999

The Salter innominate osteotomy for the treatment of developmental dysplasia of the hip in young adults.

The results were evaluated for 29 adult patients (33 hips) who had undergone a Salter innominate osteotomy because of painful developmental dysplasia of the hip (DDH). The mean age at the time of the index operation was 24.8 years (range 19-35 years), and the mean duration of follow-up was 3.5 years (range 2-8 years). Complications included one non-union and one dislocation of the osteotomy after a fall; both patients had to undergo re-operation. The mean Harris hip score improved from 65 points preoperatively to 82 points at the latest follow-up examination. In hips with no coxarthrosis (n = 11), the mean Harris hip score improved from 78 points to 89 points; in hips with coxarthrosis grade 1 (n = 15), it improved from 59 points to 85 points, while in hips with coxarthrosis grade 2 (n = 7), it improved only from 57 to 68 points. There was a diminution of coxarthrosis in 11 hips, no change in 17, and worsening in 5 hips. The mean center-edge angle of Wiberg was 11.2 deg (range 0-19 deg) preoperatively compared with 27.4 deg (range 21-37.5 deg) postoperatively and 27.6 deg at the latest follow-up examination. Our findings demonstrate that the Salter innominate osteotomy provides clinical improvement as well as radiographic improvement in adult patients with DDH, and this procedure is, compared with more complex pelvic osteotomies, a relatively simple and safe procedure with a low risk of complications.

Adult↗

PubMed1998

Different behavior of human osteoblast-like cells isolated from normal and heterotopic bone In vitro.

In this study, a characterization of human bone-forming cells responsible for heterotopic ossification was carried out in vitro. The biological and biochemical cell characteristics of the heterotopic osteoblast-like (HOB) cells were compared with those of orthotopic osteoblast-like (OB) cells from normal bone and stromal bone marrow cells believed to contain a subpopulation of osteogenic precursor cells. We found that HOB's from the spongiosa of heterotopic ossification required less time until the beginning of migration and the achievement of confluence in vitro compared with OBs from femoral shaft spongiosa. The fraction of mitotically active cells assessed by a clonogenic assay was higher as well in HOB cells. The in vitro studies of mitogenesis and the efficiency of colony formation of osteogenic cells indicate that with increasing differentiation and relative age they become more dependent on growth factors in the medium, otherwise the morphology of osteoblast-like cells changes and they pass irreversibly into the postmitotic stage of the cell cycle. The activity of the alkaline phosphatase is distinctly higher in the HOB than in the OB cells, HOB cells exhibit a lower level of osteocalcin expression compared with OB cells. No significant difference was found between OB and HOB cells in the amount of procollagen of type I sequestered by the cells. After 30 days, HOB and OB cells formed a mineralized matrix on exposure to 2 mM beta-glycerophosphate. Since HOBs were isolated from heterotopic bone that had developed within 3-6 months after hip surgery, the differences in cellular behavior compared with OBs may be attributed to the relatively young age of HOB cells.

Alkaline Phosphatase↗

PubMed1998

Prevention of periarticular heterotopic ossification after endoprosthetic hip joint replacement by means of diclofenac.

This prospective study involves 644 patients who received ossification prophylaxis by means of the drug diclofenac after implantation (87.5%) or revision (12.5%) of a total hip endoprosthesis between August 1992 and June 1994. One hundred patients (15.5%) stopped the treatment because of side-effects of the drug, and medication was stopped when gastrointestinal troubles occurred. The follow-up examination after 6 months revealed ossification of HO degree 1 according to Brooker in 13.8% of cases, of degree 2 in 4.8%, and of degree 3 in 1.4% of cases. Severe HO of degree 4 was not observed at all, and 80% of the patients exhibited no ossification what ever. Thus, in comparison to our own studies and to the literature, diclofenac must be regarded as an extremely effective drug for the prevention of ossification.

Administration, Oral↗

PubMed1998

The suppression of heterotopic ossifications: radiation versus NSAID therapy--a prospective study.

This prospective, randomized study compares the effect of postoperative irradiation and nonsteroidal anti-inflammatory drug (NSAID) therapy on the prevention of heterotopic ossifications after the implantation of a total hip endoprosthesis. A total of 154 operations were performed; one group of patients underwent radiation treatment of 3 x 3.3 Gy, and the other group took 3 x 50 mg of diclofenac per day over a period of 3 weeks. Average age, sex, preoperative diagnosis, and risk factors were similar in both groups. Postoperative radiation began on average 2.9 days after operation, and the radiation therapy was finished on average within 3.8 days. NSAID prophylaxis was begun on the first postoperative day. Heterotopic ossifications occurred in two of the patients who had undergone postoperative prophylaxis by radiation. In both cases, the ossification was Brooker I, and there was no functional impairment. There were no ossifications of Brooker II-IV in this group. One patient had a Staphylococcus epidermidis infection, and fistula revision had to be carried out; the prosthesis could be left in place. In the group treated with NSAID, 16 heterotopic ossifications stage Brooker I and 2 stage Brooker II could be detected. Eleven patients stopped the treatment because of gastrointestinal problems. Both postoperative radiation and NSAID therapy have proved to be effective prophylactic methods. In direct comparison, radiation prophylaxis by 3 x 3.3 Gy proved to be slightly more successful than NSAID prophylaxis.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1997

[Ultrasonography of Achilles tendon lesions--an experimental study].

AIM: In an experimental study the accuracy of ultrasound in the detection of lesions of the achilles tendon was examined. METHODS: 60 Achilles tendons were examined post mortem macroscopically, histologically and by means of ultrascan. RESULTS: All macroscopical changes were found in the sonograms. Especially changes of the form proved to be good diagnostic patterns for degenerative lesions of the tendon. At a distance of 2 cm proximal to the calcaneus histological changes could be detected with an accuracy of 73.3%. At 4 and 6 cm to the calcaneus we found similar results. CONCLUSION: A differentiation of the histological diagnosis by means of the sonographic behaviour was not possible. As a reproducible, effective and inexpensive method ultrasound examination has proved very useful in the detection of degenerative lesions of the Achilles tendon.

Achilles Tendon↗

PubMed1996

The Wagner revision stem in alloarthroplasty of the hip.

Forty-one Wagner revision stems were implanted at the Orthopedic Department of the University of Tübingen between July 1990 and January 1993. We report the results of 37 patients at an average follow-up of 27 months (13-48 months) postoperatively. The main indication was stem loosening with considerable loss of bone. In addition, we used the implant 4 times in primary arthroplasty. At follow-up examination 33 patients (89%) were satisfied with the postoperative outcome. According to the Merle D'Aubigné score (12-point scale), 32 patients showed a poor functional result of less than 6 points preoperatively. Postoperatively, the results of 36 patients could be classified as very good to good. To categorise the radiological destruction of the implant bed, we used the femoral shaft defect classification of the DGOT (Deutsche Gesellschaft für Orthopädie und Traumatologie) in conjunction with the classification of Pak and Paproski [5, 11]. Twenty patients presented with trochanteric and calcar defects, and 11 patients with a combination of a calcar and shaft defect. We found a circular shaft defect in 2 patients. In 7 cases we assessed the bone remodelling postoperatively as very good, with strong newly formed bone structures, and in 25 cases as good, with remodelling of the old stem bed and bony structuring of the osteolyses. A secondary sinking in of the Wagner stem was seen in 7 cases. Only one stem had to be revised because of pain symptoms and loosening; in all other cases a secondary stabilisation of the revision-stem took place. With the Wagner revision stem, there is the possibility of achieving mechanical stability even in situations with massive bone loss. The evacuation of bone cement and granulation tissues is facilitated by the transfemoral approach, bony remodelling is accelerated, and bone grafting is often not necessary. As our short-term results show, the concept is a promising one. Nevertheless, we will be very careful in following these patients in the long term, as we have noticed stem sinkage in a small percentage of cases.

Adult↗

PubMed1996

Lesions of the Achilles tendon. A sonographic, biomechanical and histological study.

Thirty-four Achilles tendons were explanted post-mortem. The explanation took place less than 24 h after death. The tendons were examined by means of ultrasonography and after explanation assessed histologically and biomechanically. In the sonograms 19 changes in echogenicity were noted. Changes in form with an increase in the diameter of the tendon of up to 10 mm (compared with the contralateral side) were found in 6 tendons. The changes in echogenicity and form were found most frequently 2-4 cm from the insertion of the tendon at the os calcis. At a speed of 5 mm/min, the average force needed until rupture occurred was calculated as 27.6 N/mm2. The tear was located on average 29.7 mm from the bony insertion of the tendon at the calcaneus. Histologically, necroses could be found most frequently in all regions of the tendon, followed by scars and fissures. When there were differences of more than 25% in tensile strength between the right and left sides, there was a histological change in the weaker tendon at the site of the tear. Sonographic changes in form pointed to histological lesions in this region. Changes in the echogenicity led to the detection of degenerative changes of the tendon, but they have to be analysed carefully, as they are prone to artefacts. There was not statistically relevant correlation either with regard to tensile strength or to the site of the rupture for sonographically proven changes in the area of the rupture. However, when there was a sonographically abnormal finding in the course of a tendon, the tendon tore at an earlier point than those exhibiting no abnormality. Sonography proved to be a useful method in the detection of degenerative lesions of tendons. A direct influence on the biomechanics of the tendon could not be found.

Achilles Tendon↗

PubMed1996

Determination of periprosthetic bone density with the DEXA method after implantation of custom-made uncemented femoral stems.

Implantation of a total hip replacement leads to resorption of bone, especially in the upper femoral shaft and this depends mainly on the design of the stem, and also on the survival time of the implant. Density of the periprosthetic bone was examined with the DEXA method in both femurs in 27 patients at a mean of 21 months after implantation of uncemented custom-made femoral stems. A loss of bone density between 5% and 21% was found which was independent of the survival time of the implant. The maximum decrease was at the upper medial part of the calcar. The negligible loss of bone density, compared to other reports, favours the use of a computer tomography assisted custom-made femoral stem.

Absorptiometry, Photon↗

PubMed1996

Ectopic bone formation by composites of BMP and metal implants in rats.

Disc-shaped implants of titanium alloy (Ti-6Al-4V) were treated on one side by corundum-blasting (CB) or by coating with hydroxyapatite (HA) or pure titanium (Ti) using plasma spraying. Half of the implants were additionally coated with purified swine BMP-3. The composites and the uncoated controls were implanted into abdominal wall-muscle pouches of rats. 25 days after implantation, ectopic bone formation could be observed macroscopically and histologically in a high frequency in all 3 groups of BMP-coated implants, whereas the controls were constantly inactive. The volumes of induced bone were similar for BMP-3-coated pure Ti and HA implants, while CB implants were significantly less active. Our findings indicate that the bone formation process is influenced by the chemical composition and by the structure of the implant surface.

Alloys↗

PubMed1995

Femoral head bone grafting for reconstruction of the acetabular wall in dysplastic hip replacement.

From 1980 through 1991 we screwed a preshaped cortico-cancellous bone graft onto the ileum wall to compensate acetabular deficiency in 94 consecutive total hip replacements. We report the results of 87 hips (79 patients) with an average follow-up of 30 months (12-75 months) postoperatively. Pain in dysplasia-coxarthrosis and congenital dislocation of the hip, destructive coxitis in rheumatoid arthritis and cup loosening was the main indication for surgery. According to the Merle d'Aubigné score the postoperative clinical evaluation demonstrated 77% very good and 18% good results. Due to component loosening the results had to be classified as unsatisfactory in 4 hips (2 cups and 2 stems). At the time of evaluation 90% of the arthroplasties was osseously consolidated as evidenced by trabecular bridging and structural integrity with host bone. Resorptions of the graft were noted in 32 hips. One cup was removed because of complete resorption and consecutive loosening, a further one was considered clinically and radiologically loose because of partial graft resorption. Two further complete resorptions and 28 partial lateral resorptions had no influence on the secondary stability of the implant. We are aware that these are short-term results. Nevertheless, we recommend the described method as a valuable addition to arthroplasties for acetabular rim defects both in osteoarthritis and in revision surgery.

Acetabulum↗

PubMed1995

[Osseointegration of titanium test bodies of different surface properties in metaphyseal bone sites of the dog--a biomechanical and histological analysis].

The alternative to the anchoring of an endoprosthesis by means of cement is the biological fixation by an ingrowth of bone into the implant surface (osseointegration). We examined the implant fixation properties of titanium experimental devices with 3 different surface structures after press-fit implantation into the bony bed of 12 dogs. One third of the 48 implants had a micro-structured surface roughened by grit-blasting, one third a roughened surface with an additional macro-groove structure (combination surface), and the remaining third a porous hydroxyapatite (HA) coating. Twelve weeks after implantation the bony ingrowth was evaluated biomechanically by measuring the force required to pull out the implant from the surrounding bone and histologically by morphometric assessment of microradiographs. In the pull-out-experiment the shearing forces were significantly lower (p < 0.01) in the devices with a roughened surface in comparison to the devices with a micro- and macro-structured surface and the HA surface. Thus, there was no significant difference between the forces required to pull out the devices with the porous HA surface and those with the combination surface. The histomorphometric assessment of bone density in the immediate vicinity of the implant and the extent of the direct contact surface of the bone implant resulted in no significant difference in all 3 groups. We did not find an interposing layer of fibrous tissue at the interface. We can demonstrate that roughening of the surface in combination with a groove structure creates a better bond between implant and bone than a roughening alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Isokinetic force-velocity curves in patients following implantation of an individual total hip prosthesis.

There are only a few studies which could support conclusions concerning the strength of the muscles surrounding the hip joint and especially concerning the strength relationships following implantation of endoprostheses. The aim of this study was to examine the post-operative course of strength deficits in this musculature compared to clinical parameters. Fifty-eight patients between 30 and 67 years of age, in whom individual total hip prostheses were implanted, were clinically examined prior, 9 weeks and 6 months after surgery. Moreover, the maximum isometric strengths of abductors, flexors, and rotator muscles as well as maximum isokinetic strengths of the extensors and flexor musculature at 60 degrees/s and 120 degrees/s were measured. The flexor and extensor musculature already showed a clear increase in maximum strength after 9 weeks and 6 months. By contrast, the isometric strengths of the rotators increased only slightly, the abductor strength decreased after 9 weeks to below the preoperative baseline level and attained this level again only after 6 months. The clinical parameters Trendelenburg sign, limping, and walking capacity were clearly improved after 6 months, but no correlation to the abductor strength could be demonstrated. It is concluded that limp-free gait can be attained even without maximum strength increase in the abductors, which are important for fluid gait, at least for short distances. The importance of regular training of the rotator and abductor musculature in coxarthrosis is emphasized to delay limitation of movement and decreased strength in the sense of a capsule pattern.

Adult↗

PubMed1993

Kinematics of the Zielke procedure (VDS) in scoliosis. Intraoperative measurements.

The Zielke correction technique (VDS) has two parts, derotation and ventral convex-side compression. Both were studied by measurements made during and after the operation. Ventral derotation always creates lordosis. Lordosis can be maintained during compression by insertion of intervertebral bone blocks, or kyphosis created by omitting them.

Biomechanical Phenomena↗

PubMed1993

Osteogenic activity of bone morphogenetic protein and hydroxyapatite composite implants.

In an experimental study in rats hydroxyapatite (HA) ceramics of characteristics and inactive rat bone matrix were investigated comparatively for their suitability as carriers for osteoinductive factors. Bone morphogenetic protein was extracted from long bones of pigs under dissociative conditions and partially purified by gel filtration. The resulting pBMP was combined with the granular hydroxyapatite ceramics Osprovit, Algipore, Frialit and inactive rat bone matrix (IBM) by precipitation of aliquots of this pBMP fraction onto pellets of each carrier material. The osteogenic activity of these composite implants and of corresponding controls was bioassayed by implantation into muscle pouches of immunodeficient rats. All pBMP-HA ceramic implants elicited ectopic bone formation within 25 days after implantation, whereas control implants did not show any osteoinductive ability. Alkaline phosphatase (AP) activity of the explant tissues was determined for quantitation of bone formation. Due to the high incidence of bone formation found in each pBMP group all HA ceramics tested seem to be basically suitable as carriers for osteoinductive factors. Algipore, a highly porous phycogen HA ceramic, was found to be quantitatively superior to all other materials investigated due to its very large surface available for protein binding.

Animals↗