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Biomedical subjects

H G Simank

Publications and source records attributed to H G Simank.

At least 19 recordsLinked to original sources
PubMed2005

[Improving microbiological diagnostics in septic orthopaedic surgery. Comparative study of patients receiving systemic antibiotic therapy].

MATERIAL AND METHODS: This prospective study included 63 patients with confirmed infections of soft tissue, joints, bones or implants. During 110 surgical interventions, 124 swab and deep tissue sample pairs were taken and analysed microbiologically using standard procedures. RESULTS: In 40 patients who had not received prior antibiotic treatment, 57 sample pairs (swabs/tissue) were taken. In 70%, growth of microorganisms could be observed in both swabs and tissue samples. Growth in tissue sample only was observed in 14% and in 14% no growth could be detected. In 67 sample pairs taken from 23 patients who had received systemic antimicrobial treatment prior to surgery, microbial growth in both specimens was detected in 40%. Growth in tissue sample only was observed in 22% and 34% of the samples remained without detectable growth. The overall sensitivity of the tissue samples (70%) was significantly higher than in swab samples (44%) for the pretreated group. CONCLUSION: The use of intraoperative tissue samples for microbiological diagnostics in septic orthopaedic surgery must be considered a "gold standard". The higher sensitivity of intraoperative tissue samples is particularly important in patients receiving systemic antibiotic therapy prior to surgical interventions.

Anti-Bacterial Agents↗
PubMed2005

[Garden I femoral neck fractures: conservative vs operative therapy].

INTRODUCTION: Treatment recommendations vary for Garden I fractures of the proximal femur. The aim of our retrospective study was to determine the results of functional treatment of these injuries. MATERIAL AND METHODS: A total of 54 consecutive patients were enrolled, and their data (age, comorbidities, treatment, complications, etc.) were ascertained and stored in a database. Initial treatment consisted in early mobilization and weight bearing in all patients. RESULTS: In 24 cases (44%) no complications at all were observed in the course of conservative treatment. In 28 cases (52%) surgical treatment was necessary due to early fracture dislocation. Analysis of the X-ray images showed that in 9 of these 28 cases the functional treatment had not been clearly indicated, i.e., incomplete impaction of the fragments. When these patients are excluded the success rate of conservative treatment was 53%, as two additional late complications occurred and were treated surgically (1x AVN, 1x nonunion). With reference to the survival rate, score, and patient satisfaction, there was no difference between conservative and operative treatment (p=0.478). The risk of a secondary dislocation increases with the number of risk factors (p=0.008). DISCUSSION: An attempt at functional treatment with close X-ray monitoring is appropriate in these fractures, since this makes it possible to avoid surgery in about half of the patients while achieving functional results comparable to those yielded by surgery.

Aged↗
PubMed2004

[Adult mesenchymal stem cells for the regeneration of musculoskeletal tissue].

Mesenchymal stem cells can be isolated from human bone marrow aspirates, and, thanks to their differentiation potential and good in vitro culture properties, represent an attractive cell line for the replacement of mesenchymal tissue, i. e. tissue engineering. Both in vitro and in vivo, they can differentiate into cartilage, bone, tendons and fat cells, and--in contrast to embryonic stem cells--are not underethical scrutiny. Cultured in three-dimensions on a variety of carrier substances, they have already been successfully employed for the reconstruction of mesenchymal tissues in numerous studies involving both small and large animal models. While a clinical application in humans has also been successful in pilot studies, numerous points still remain to be clarified, underscoring the need for further intensive research before wide-scale clinical application can be contemplated. Only then can it be shown whether the associated high expectations are justified.

Animals↗
PubMed2004

[Allogenic transplantation of human mesenchymal stem cells for tissue engineering purposes: an in vitro study].

Due to their plasticity and high proliferation capacity in vitro, human mesenchymal stem cells (MSC) are promising candidates for tissue engineering approaches of mesenchymal tissues like bone, cartilage, or tendon. Undifferentiated MSC do not express immunologically relevant cell surface markers. They inhibit the proliferation of allogeneic T-cells in vitro and elicit no immune response after allogeneic or xenogenic transplantation. Thus, MSC ought to be seen as immunoprivileged or immunomodulating cells. Here, we characterize the immune status and -behavior of MSC and MSC-derived osteogenic precursors in order to evaluate the usefulness of allogeneic MSC for tissue engineering of bone. Human MSC were isolated from bone marrow of hematologically normal voluntary donors. Osteogenic differentiation was induced by adding dexamethasone, ascorbic acid and beta-glycerophosphate. After 0, 8, 16 and 24 days, MSC were co-cultivated with allogeneic mononuclear cells. In parallel, the expression of immunologically relevant cell surface markers was monitored by flow cytometry. Undifferentiated and differentiated MSC did not stimulate allogeneic lymphocytes. MSC were negative for MHC-II, CD40, CD40L, CD80 (B7-1) and CD86 (B7-2), positive for MHC-I, and kept this expression pattern during osteogenic differentiation. Our results support the hypothesis that MSC are immunoprivileged cells which are potentially at disposal for HLA-incompatible cell replacement therapies.

Bone Regeneration↗
PubMed2003

[Experiences with vascular pedicled fibula in reconstruction of osseous defects in primary malignant bone tumors].

To bridge large bone defects after resection of primary malignant bone tumors, an autologous free vascularized fibular graft was used in 31 patients (15 x upper limb, 16 x lower limb). The median bone defect measured 16 cm (7-29.5 cm). At the lower extremity the vascularized fibular transplant was reinforced with an allograft and different osteosyntheses. At the upper limb stabilization of the transplant was obtained exclusively by plate osteosynthesis or condylar plate. Applications and the authors' experiences are described and discussed in terms of clinical outcome, graft union, functional outcome, and complications for each localization. After a median of 48 months, ten complications at the upper limb and eight complications at the lower limb, respectively, were seen requiring secondary surgical revision. Major complications such as perioperative deaths or secondary amputations were not observed. Functional evaluation showed better results for the lower than for the upper extremity, due mainly to en bloc resection of proportionally large amounts of soft tissues around the shoulder girdle for local tumor control. Despite the demanding operative procedure and a large number of controllable complications, the good functional outcome and high patient satisfaction indicate that the free vascularized fibular graft is an option for limb-sparing surgery of primary malignant bone tumors.

Adolescent↗
PubMed2001

[Injury pattern in shoulder dislocation in the elderly patient].

PROBLEM: Recurrent shoulder dislocation is reported to be rare in older patients. While injuries of the glenoid labrum and the anterior capsule following primary dislocation in younger patients seem to determine the rate of instability, the pattern of damages in the elderly has rarely been studied. METHODS: 91 patients with an age older than 40 years with the diagnosis of primary (group A, n = 50) or recurrent (group B, n = 41) anterior shoulder dislocation were included in a prospective study. By analysis of the findings in x-rays, MRI, CT-scans and in 36 patients of diagnostic arthroscopy the pattern of intra- and periarticular pathology was evaluated. RESULTS: While the incidence of bony Bankart- and Hill-Sachs lesions was constantly spread over the age groups the pattern of soft tissue damages was different. Up to the age of 60 years lesions of the glenoid labrum were leading while in older patients the prevalence of rotator cuff tears became about 70 percent. CONCLUSIONS: The development of secondary osteoarthritis and persisting symptoms in older patients with rotator cuff tears after traumatic shoulder dislocation requires early diagnosis and appropriate treatment.

Adult↗
PubMed2001

Comparison of results of core decompression and intertrochanteric osteotomy for nontraumatic osteonecrosis of the femoral head using Cox regression and survivorship analysis.

Different surgical procedures have been recommended for osteonecrosis of the femoral head to prevent or delay the need for arthroplasty. Core decompression is a commonly used treatment in the early stages of the disease, but the published efficacy has varied markedly. Only a few comparisons of different techniques have been reported. The aim of this study was to evaluate and compare the results of 2 commonly used procedures, core decompression and intertrochanteric osteotomy, using Cox regression and survivorship analysis. A total of 177 cases with a mean age of 41 years at surgery were treated for osteonecrosis (94 core decompressions, 83 osteotomies). Any further surgery was defined as failure and endpoint. Significant risk factors for treatment failure were age > 40 years at surgery (P = .022), corticosteroid intake (P < .001), advanced stage of necrosis (Steinberg stage > or =III, P=.04), and core decompression (P = .084). To analyze the influence of the surgical procedure, patients with corticosteroid treatment were excluded, and survival analysis was performed. This analysis revealed survival rates of 74% after osteotomy and 78% after core decompression 6 years postoperatively in early, precollapse stages (P = .819). In advanced stages, the rate of survival for hips after core decompression was lower (56%) than in hips after osteotomy (76%) (P = .056). Our results indicate that core decompression may be as effective as intertrochanteric osteotomy in precollapse stages but is less traumatizing and is cost-effective. For postcollapse hips, intertrochanteric osteotomy should be considered.

Adolescent↗
PubMed2001

A growth and differentiation factor-5 (GDF-5)-coated suture stimulates tendon healing in an Achilles tendon model in rats.

Growth and differentiation factor-5 (GDF-5) is essential for normal skeletal development and induces tendon-and ligament-like structures at ectopic sites. Therefore, we investigated the influence of a GDF-5-coated suture on the healing Achilles tendon in rats. The right Achilles tendon in 80 rats was transected and sutured with an absorbable polyglactin suture. Animals were randomized to an uncoated-suture control and a GDF-5-coated suture group. At 1, 2, 4 and 8 weeks after surgery the repair tissue was evaluated biomechanically and histologically. Biomechanical testing revealed significantly thicker tendons, which were stiffer at 1, 2, and 4 weeks, in the experimental group than in the control group. The maximum tensile strength was significantly increased at 2 weeks after surgery. Histologically we found cartilage-like cell nests 4 weeks after tendon repair, which were positive for type II collagen. In conclusion, local growth factor delivery by a coated suture material showed a promising beneficial effect on tendon repair. The appearance of cartilage-like structures may demonstrate the chondroinductive capacity of GDF-5, which in these circumstances, however, might be overcome by modifications of the GDF-5 dose and/or the suture material.

Achilles Tendon↗
PubMed2001

Bone morphogenetic protein-2 and growth and differentiation factor-5 enhance the healing of necrotic bone in a sheep model.

INTRODUCTION: Osteotropic growth factors enhance bone repair, but their efficacy in an area of necrotic bone is not known. The purpose of this study was to investigate the effects and potential side effects of an intraosseous application of absorbable bone morphogenetic protein-2 (BMP-2) and growth and differentiation factor-5 (GDF-5) composites in a sheep model for partial necrosis of the femoral head. MATERIALS AND METHODS: The direct injection of ethanol under fluoroscopy into the superior centre of the right femoral head produced histologically documentable necrosis of the central region of the head in a previous study of ten sheep. Another 27 sheep constituted the sample to study the effects of BMP-2 and GDF-5. Necrosis was produced in the same fashion in these animals. Four weeks later nine sheep received 300 microg recombinant BMP-2 and nine sheep 300 microg recombinant GDF-5 on an absorbable carrier by surgical implantation. Nine sheep received the carrier alone (control group). The animals were sacrificed at 3, 6, and 12 weeks after implantation and both femora were harvested. RESULTS: Bone density analysis and microscopic examination indicated that bone formation was noticeably induced as early as 3 weeks postoperatively in the growth factor treated animals. Bone regeneration was enhanced by growth factor composites. This was documented by histological scoring and histomorphometric analysis. No severe local side effects secondary to the growth factors, such as heterotopic ossification or inflammation, were observed in either group. DISCUSSION: The application of an absorbable growth factor composite in combination with established surgical techniques is a promising approach, that may enhance the healing of devitalised bone defects. Based on these results, further studies regarding biodegradation, dosage of the protein and surgical technique are required.

Animals↗
PubMed1999

Core decompression in osteonecrosis of the femoral head: risk-factor-dependent outcome evaluation using survivorship analysis.

The results of core decompression of the femoral head in the treatment of osteonecrosis are analyzed. This study includes 94 hips in 74 patients with a follow-up time ranging between 18 months and 15 years (average 6 years). There had been no need for further surgery 2 years postoperatively in 85% of the hips with preoperative Steinberg stages 0, I and II when compared with 66% with preoperative stages III, IV and V. At 4 years postoperatively the corresponding figures are 73 compared to 55%; and 6 years postoperatively 69 compared to 49%. This difference was significant (P=0.0402). Further significant risk factors are corticosteroid administration, smoking and alcohol intake. The results of core decompression are good when the preoperative lesion is at Steinberg stage 0, I and II and the patient does not present with other risk factors. In cases with risk factors the outcome is significantly less good. The procedure is not indicated in the presence of advanced disease.

Adolescent↗
PubMed1998

[Cementless hip prosthesis in inflammatory rheumatic diseases].

We compared the outcome of cementless hip arthroplasty in patients with chronic rheumatic diseases (cases) and patients with osteoarthritis (controls). Between 1985 and 1993 we implanted 26 cementless hips in 22 patients with Rheumatoid Arthritis, Psoriatic Arthritis or Ankylosing Spondylitis. From a pool of more than 600 patients with Osteoarthritis we chose 40 matched controls (41 hips). Matching variables were year of implantation, age, follow-up, height, weight, gender and type of implant. At follow-up (cases: 58 +/- 27 months; controls: 56 +/- 26 Monate) no signs of loosening or migration of the stem were found, neither in the cases nor in the controls. Loose and/or migrated cups were found in 4 patients with rheumatic diseases (after 44, 65, 65 and 107 months) and in 3 patients with osteoarthritis (after 63, 84 and 100 months). Two cups were revised within 18 months in the control group, in the case group one revision was necessary after 5 years. Loosening and revision rates did not differ significantly (p > 0.20). Clinically, those with Osteoarthritis had a better extension (p < 0.02), were more satisfied with their (artificial) hips (p < 0.05) and did better in some activities of daily living (climbing stairs, dressing, sitting/standing up). Within a mean follow-up of 5 years the results of patients with chronic rheumatic diseases seem to be comparable to those of a matched control-group of patients with Osteoarthritis. Differences between the groups concern areas, in which rheumatic patients are handicapped due to their chronic illness. Nevertheless, we need long-term-results, before we can recommend cementless implants for these patients.

Aged↗
PubMed1998

Periprosthetic mineralization around cementless total hip endoprosthesis: longitudinal study and cross-sectional study on titanium threaded acetabular cup and cementless Spotorno stem with DEXA.

In a prospective longitudinal study over 2 years and a separate cross-sectional study more than 5 years after operation, we analyzed periprosthetic bone mineral density (BMD) after cementless total hip arthroplasty (THA) (press-fit cementless Spotorno stem, Mecron threaded acetabular cup) by dual-energy X-ray absorptiometry (DEXA). BMD was analyzed in a longitudinal prospective study (n = 53 patients: 29 women, 24 men) and in a separate cross-sectional study (n = 23 patients: 13 women, 10 men) with good clinical outcome (Merle d' Aubigne score > 12). Regions of interest were defined according to Gruen (ROI 1-7) and as netto average ROI (NETAVG I) for the periprosthetic femur, and according to De Lee and Charnley (ROI I-III) and as NETAVG II for the periprosthetic acetabulum. BMD during follow-up was compared with immediate postoperative values of the affected limb. Mean precision error (CV%) was 2.6 +/- 0.5% for ROI 1-7 and 1.3 +/- 0.9% for ROI I-III. BMD significantly decreased in the periprosthetic femur and acetabulum during the first 3 months after operation. At the femur, BMD (NETAVG I) for women and men, respectively, was 92.4% and 87.5% at 6 months, then 89.4% and 96.2% at 2 years. ROIs around the proximal stem showed the lowest absolute values and decreased most during follow-up (to 79.9% ROI 1 and 68.2% ROI 7, respectively). Mineralization around the cup (NETAVG II), respectively, amounted to 81.1%, 82.6% at 6 months, then 80.1% and 93.8% at 2 years. The medially placed ROI II demineralized most (respectively, 72.1% and 76.7%). More than 5 years after THA, BMD in the femur showed little change, but decreased significantly to 76.4% and 79.1%, respectively, around the cup (NETAVG II). DEXA is a useful method for analyzing changes of mineralization around cup and stem of cementless THA. The results reflect the different stress on the periprosthetic bone after implantation of THA in defined ROIs, supporting earlier reported good clinical results of the Spotorno stem and increased loosening rate of threaded acetabular cups after 5 years.

Absorptiometry, Photon↗
PubMed1997

Middle-term results of threaded acetabular cups. High failure rates five years after surgery.

We report our results using three different threaded acetabular components (Mecring A, Mecring B and Weill) in 715 hips with a follow-up of between one and ten years (median: 99.1, 56.5, 38.3 months, respectively). All cups were implanted with one type of cementless stem. The clinical results were good or acceptable in about 70% of the hips, but signs of loosening with radiolucency and/or migration were found in 10.1%. Radiological evidence of loosening did not correlate significantly with the clinical outcome. Pain was not a reliable indicator of loosening and its absence sometimes allowed severe osteolysis to develop. Twenty-five hips were revised (3.5%) for aseptic loosening of the acetabular component. Kaplan-Meier estimates of the cumulative rate of failure showed a rapid increase five years after the initial operation, but no significant correlation with gender, age or weight. The high rate of failure indicates that further use of these acetabular components cannot be recommended. Annual radiographs are required to assess osteolysis even if the patients are free from pain.

Acetabulum↗
PubMed1997

Long-term effects of core decompression by drilling. Demonstration of bone healing and vessel ingrowth in an animal study.

Avascular necrosis of the femoral head is associated with bone marrow hyperpression. Although core decompression by drilling is an accepted treatment regimen, until today no experimental results exist concerning the physiological effects of this procedure. Published clinical data are controversial. In an animal study marrow decompression was carried out by drilling of both hips in 18 healthy male sheep. In the right hip of each animal a resorbable stent was implanted in order to prolong the duration of core decompression. Over a time period of 24 weeks the effects were studied by measurement of the intraosseous pressure, by the plastination method and by morphological examination with light and electron microscopy. Bone drilling is a procedure of high short-time efficacy in decompressing the bone marrow. But decompression lasts only for a short time period. Three weeks postoperatively the drill channel is sealed by hematoma and fibrous tissue in both hips (with/without stent) and no significant decompressive effect is measured. Ingrowth of vessels along the drill channel is found in all hips after a time period of 3 weeks. These vessels originate from the periosteum as well as from the bone marrow and form temporary anastomoses between the periostal-diaphyseal-metaphyseal and the epiphyseal-physeal circulatory system. In conclusion, for the first time an anastomosis induced by drilling between both circulatory systems of bone is demonstrated and the importance of the periosteum is confirmed. The time of decreased core pressure induced by drilling is too short for substitution of a necrotic area and could be the explanation of the inferior clinical results of the procedure.

Animals↗
PubMed1993

The Haglund imprint on the patella.

Seven hundred and five radiographs of the knee were examined and 17.6% showed a so-called Haglund imprint on the patella. The incidence was the same in patients with chondromalacia and in a control group. There was no statistical difference regarding age, sex and body weight. Haglund's imprint is a variation from the normal and is of no diagnostic value.

Body Weight↗
PubMed1993

[Undiagnosed fractures of all metatarsals in a diabetic woman].

In the case presented here we demonstrate the history of a 31-year old woman who had been known to be diabetic for more than 10 years. In the beginning she complained of an isolated fracture of the first metatarsal bone. Because of incomplete immobilisation, but without major trauma, fracture of the metatarsal I-V developed. On an outpatient basis diagnosis was delayed for 6 months because of a misinterpreted scintigraphy without performing x-ray examination. In our clinic treatment consisted of immobilisation in a cast and non-weightbearing. The update knowledge diabetic osteopathy and osteoarthropathy and the consequences for treatment are discussed.

Adult↗