Biomedical subjects

R Schnettler

Publications and source records attributed to R Schnettler.

At least 37 records · Page 2Linked to original sources

PubMed2004

Effects of platelet growth factors on human mesenchymal stem cells and human endothelial cells in vitro.

The aim of the present in vitro study has been to investigate the effects of a enriched platelet derived growth factors on proliferation and migration of human endothelial and mesenchymal stem cells and on osteogenic differentiation of stem cells. Platelet rich plasma has been produced, yielding a four time higher number of thrombocytes than normal plasma. Degranulation of platelets has been performed by means of calcium and thrombin. Plasma has served as a control, whereas plasma in combination with calcium and thrombin was used to distinguish the difference between calcium and/or thrombin mediated effects and growth factor induced effects on the cells. The observed enhanced proliferation and migration of endothelial cells towards the platelet derived growth factors was driven by the plasma component of these preparations. However PDGF solely stimulated the migration and proliferation of mesenchymal stem cells. The increased osteogenic differentiation of growth factor treated mesenchymal stem cells was mostly driven by the high level of calcium used for the platelets degranulation. In summery, the different components of platelet derived growth factors work together to influence human endothelial and mesenchymal stem cells. This is of special clinically interest regarding the stimulation of bone healing in orthopaedic and traumatic surgery.

Animals↗

PubMed2004

Treatment of pain from osteoporotic vertebral collapse by percutaneous PMMA vertebroplasty.

BACKGROUND: Vertebral compression fractures are common complications in advanced osteoporosis. In general, this disease of the elderly patient is characterized by severe local back pain. Pathophysiologically, bony instability triggers local pain during body movement. Serious pain immobilizes the patients and forces them to bed rest. As a result, complications like thrombosis or pneumonia occur. Invasive treatment with surgical instrumentation for vertebral stabilization is not indicated in elderly patients especially with additional diseases. The purpose of this study was to test the hypothesis that percutaneous polymethylmethacrylate (PMMA) vertebroplasty significantly reduces pain due to vertebral collapse in osteoporotic patients and improves quality of life. METHODS: A total of 38 patients with osteoporotic vertebral compression fractures of the thoracic and lumbar spine were treated by PMMA vertebroplasty. After admission, before discharge from the hospital, six weeks, half a year and one year later patients answered the Oswestry Low Back Pain Disability (OLBPD) Questionnaire for assessment of treatment related change in disability. In all patients percutaneous vertebroplasty was performed under local anesthesia. FINDINGS: A total of 92% of patients reported a significant pain reduction immediately after treatment. Also one year after vertebroplasty pain remained significantly reduced. Vertebroplasty was highly beneficial for patients with pain related to local instability of the spine. Extravasation of PMMA beyond the vertebral margins was observed in 26% of the cases. No treatment related clinical or neurological complications were noticed. INTERPRETATION: PMMA vertebroplasty is a useful and safe method of pain relief which rapidly regains quality of life for patients with osteoporotic vertebral compression.

Administration, Cutaneous↗

PubMed2004

[Difficulties involved in the Hoffa fractures].

To study the outcome in Hoffa fractures regarding the type of fracture, concomitant injuries, and different treatments. From January 1996 until December 2002, 7 Hoffa fractures (6 patients) from a total of 79 distal femoral fractures were treated in the Department of Trauma Surgery, University Hospital of Giessen. The results were evaluated by Neer's score. For the evaluation of postoperative vascularization of the distal femur, clinical and radiological findings were compared with anatomical studies of the bone arteries by corrosion preparations. Fracture consolidation was seen in all cases. Patients with an isolated Hoffa fracture achieved a score of 89.0 (82-97) according to Neer. One patient suffering initially from nonunion achieved 68 points after bone union. One polytraumatized patient with bilateral Hoffa fracture achieved a satisfying result (score value of 72) and a bad result (score value of 38). Multiple small nutrient arteries of the distal femur originate from the "rete articulare genus." They can be expected to ensure the arterial blood supply. Hoffa fracture is a very rare injury. In our patients, careful surgical treatment with open reduction and safe screw fixation yielded good to very good results.

Adult↗

PubMed2004

[Nanoparticulate silver. A new antimicrobial substance for bone cement].

BACKGROUND: Multiresistant bacteria have become an important problem in prosthetic joint infections. Their frequent resistance against gentamicin, which is commonly used in antibiotic-loaded bone cements, makes a new prophylaxis necessary. METHODS: PMMA-cement was loaded with 1% nanoparticulate silver and its antibacterial activity tested in vitro against gentamicin-resistant MRSE and MRSA strains as well as being compared to the activity of plain and gentamicin-loaded bone cements. A quantitative elution testing was also done to study the potentially cytotoxic effects of NanoSilver cement. RESULTS: Unloaded and PMMA-cement loaded with 2% gentamicin did not exhibit any antibacterial activity against MRSE and MRSA. At 1%, NanoSilver cement completely inhibited the proliferation of MRSA and MRSE. NanoSilver bone cement did not show any significant differences compared to the non-toxic control group. CONCLUSIONS: If these promising in vitro results can be confirmed in vivo, NanoSilver bone cement may be of considerable value in total joint arthroplasty.

Animals↗

PubMed2004

Expression of EDA+ and EDB+ fibronectin splice variants in bone.

The extracellular matrix component fibronectin (fn) has fundamental functions in cell attachment, differentiation, proliferation, and migration. Isoforms of cellular fibronectin, named EDA+ fibronectin or embryonal EDB+ fibronectin, are generated by alternative splicing of its mRNA precursors. Little is known about the expression of EDA+ and EDB+ fibronectin splice variants in human bone. The aim of this study was to investigate the expression pattern of fibronectin splice variants in bone cell lines and in different human bone tissue samples (mature bone, early stages of fracture healing, hypotrophic nonunion, osteosarcoma). Analysis was done by immunostaining with recombinant and monoclonal antibodies, qualitative RT-PCR and LightCycler-based real-time quantitative RT-PCR assay. In osteoblast and osteosarcoma cell lines, abundant expression of EDA+ and EDB+ fibronectin was found in immunocytochemistry. High transcription levels of both splice variants mRNA were seen in quantitative RT-PCR in osteosarcoma cell lines. In mature bone, EDA+ and EDB+ were not detectable in immunohistochemistry. Transcription of mRNA in both splice variants was absent in these samples. Early stages of fracture healing and osteosarcoma cell samples exhibited extensive staining for EDA+ and EDB+ fibronectin, and high mRNA levels were found. Both osteosarcoma and bone fracture healing tissue expressed high mRNA levels of the fibronectin splice variants independent of benign or malignant behavior. Low level of EDA+ fibronectin mRNA transcription and focal immunohistochemical staining of EDA+ fibronectin was found in hypotrophic nonunions, whereas EDB+ fibronectin was not detected by immunohistochemistry and qualitative or quantitative PCR. EDA+ fibronectin was found in granulation tissue-forming processes in bone independent from bone-forming activity. EDB+ fibronectin was seen only in high-turnover new osteoid-forming processes like early stages of fracture healing and osteosarcoma and was absent in low-turnover processes like mature bone and hypotrophic nonunion. Both EDA+ and EDB+ fibronectin mark active processes in bone without differentiation between malignant or benign activity. In conclusion, EDA+ and EDB+ fibronectin splice variants are strong markers for active fibrogenetic and osteoid-forming processes in human bones.

Adolescent↗

PubMed2004

[Properties and degradation of a new bioresorbable bone glue].

In trauma surgery gluing is an attractive method of bonding fractured bone, which is rapid and does not require the use of screws and plates. The purpose of this study was to analyze in vitro the properties of a new bioresorbable bone glue, and in vivo its structure and degradation. The newly developed bone glue is based on alkylenbis(oligolactoyl)methacrylates and employs a two-component initiator system. Starting components for synthesis are ethylene glycol, lactic acid and methacrylic acid. In vitro the solidified glue is degraded via hydrolysis of ester bonds. Degradation products are ethylene glycol, lactic acid and oligomeres of methacrylic acid. After the first week polymer pellets (MMA, HEMALA, ELAMA) showed a weight loss of 12%. From week 2-20 a linear weight loss of 1.5% per week, that is 40% after 20 weeks, was observed. The in vivo investigations of the ultrastructure of the glue revealed a transparent and homogeneous mass with large electron-tight vacuoles. Differences in structure and degradation were not observed. Degradation of glue by hydrolysis and phagocytosis, with good biocompatibility was demonstrated.

Absorbable Implants↗

PubMed2004

[Biochemical bone marrow markers and their significance in postmenopausal osteoporosis--a new method in the diagnosis of osteoporosis?].

This study analyzes the qualification of biochemical markers in the diagnosis of osteoporosis and evaluates the potential of a multiparametric classification of premenopausal and non-osteoporotic as well as osteoporotic postmenopausal women, which is based on biochemical marker profiles. For this evaluation data of 29 women in the age between 28-74 years were used. The classification of osteoporosis was done by the trabecular density of the lumbar spine using qCT-measurements. The biochemical markers of formation and resorption AP, bAP, OC, ucOC, PICP, PYD, DPD, NTX, BSP and vitamin K were analyzed on day 1 and 42 in all patients. For vitamin K we found significant distribution differences between non-osteoporotic and osteoporotic women (p<0.005). The crosslinks PYD and DPD showed weakly significant differences. All other parameters exhibited non-significant results. Vitamin K acted with a sensitivity of 64% and a specificity of 82%. The used multiparameter classification process improved sensitivity and specificity considerably. The parameter profiles of OC/PYD, vitamin K/PYD and vitamin K/bAP revealed the highest sensitivities with specificities of more than 82%.

Adult↗

PubMed2003

In vivo mechanisms of hydroxyapatite ceramic degradation by osteoclasts: fine structural microscopy.

In the present study the in vivo mechanism of calcium-phosphate (CaP) ceramic degradation has been investigated by means of transmission electron microscopy. The results revealed osteoclast-mediated degradation of hydroxyapatite ceramic implanted into sheep bone by simultaneous resorption and phagocytosis. After 6 weeks of implantation, osteoclasts were localized immediately beneath the ceramic surface. They had formed resorption lacunae and exhibited typical ultrastructural features, such as the ruffled border, the clear zone, and the dorsal microvilli. Their resorption capacity also had become evident by alterations of the electron density and the shape of the CaP crystals localized within the acidic microenvironment of the ruffled border. Moreover, the osteoclasts simultaneously were capable of phagocytosing the resorbed CaP crystals. The formation of endophagosomes was performed (1) by the uptake of particles into large intracellular vacuoles, which were generated by deep invagination of the membranes of the osteoclastic ruffled border, and (2) by the encircling of particles due to the development of pseudopodia-like plasmaprotrusions of the ruffled border. The formation of endophagosomes was followed by the in situ fragmentation of the inclusion material, which subsequently was released into the extracellular space and phagocytosed by macrophages.

Animals↗

PubMed2003

[Polymethylmethacrylate-vertebroplasty. A new and effective method of pain treatment in vertebral compression].

BACKGROUND AND OBJECTIVE: Percutaneous polymethylmethacrylate (PMMA) vertebroplasty is increasingly used in the treatment of back pain related to compression of the vertebral bodies. After the procedure immediate mobilization of the patient is possible. The purpose of the study was to examine the change in quality of life of patients with vertebral collapse achieved by vertebroplasty during a six-month period. PATIENTS AND METHODS: 28 patients with osteolytic metastases (mean age 59,7 +/- 7,8 years, 2,1:1male/female ratio) and 38 patients with osteoporotic vertebral collapse (mean age 73 +/- 6 years, 1:3,5male/female ratio ) of the thoracal and lumbar spine were treated with PMMA vertebroplasty and analysed prospectively. After admission, before, six weeks and 6 months after discharge from the hospital patients answered the Oswestry Low Back Pain Disability (OLBPD) questionnaire for assessment of treatment-related changes in disability. RESULTS: Immediately and 6 months after treatment 83 % of tumor patients and 92 % of ostoporotic patients had significant pain reduction. Extravasation of PMMA beyond the vertebral margins were observed in 26 % of the patients. No treatment-related clinical or neurological complications were observed. CONCLUSION: PMMA vertebroplasty is an efficacious and safe method of pain relief for patients with osteolytic metastases or osteoporotic compression with good long-term results.

Aged↗

PubMed2003

[Penetrating knife injury of the heart. Emergency management and definitive treatment: case report and review of the literature].

The outcome of patients with penetrating heart injuries depends to a great extent on aggressive primary care and fast transport to the closest appropriate trauma center. There, after confirming the diagnosis, the injured victim has to be transferred without any delay to the operating room where the penetrating injury can be dealt with. The importance of resolute emergency management is shown based on a case presentation and a review of the current literature. The employment of extracorporal circulation (heart-lung machine) is rather subordinate in the primary care of these patients.

Adult↗

PubMed2003

[Ultrastructural examination of cell-mediated degradation of a calcium phosphate ceramic].

Up to now little is known about cell-mediated degradation of biomaterial surfaces, especially as methodologically significant studies are not available. Therefore, the present study focused on ultrastructural details of cells involved in degradation of calcium phosphate ceramics. For the experimental procedure six adult sheep were used. At the medial aspect of the left hindlimb a cylindrical defect was created at the level of the proximal epiphysis of the tibia. Subsequently, a calcium phosphate paste was packed into the defect. Six weeks after implantation, specimens from the implants fixed by perfusion were examined histologically and by transmission electron microscopy. The results of light microscopy revealed substitution of the ceramic by newly formed lamellar bone. Electron microscopy indicated multinucleated cells localized at the implantation site and the bone surface, corresponding to osteoclasts. They formed resorption lacunae and revealed typical ultrastructural features such as the ruffled border and the sealing zone. Osteoclast-mediated degradation was performed by simultaneous resorption and phagocytosis. For the first time this degradation mechanism was documented in vivo. It confirms the notion that osteoclasts are members of the monocyte/macrophage family.

Animals↗

PubMed2003

[Operative treatment of extended peritendinous calcifications after open Achilles tendon repair-a case report].

In the recent literature, there are only a few hints on spontaneous or postoperative heterotopic ossifications of the Achilles tendon region. The strategies of treatment are different, both conservative and operative. Postoperative calcifications are not mentioned as typical complications in the treatment of Achilles tendon ruptures. We describe the case of a 39 year old male suffering of an increasing, painful swelling and a decrease of loading capacity. In clinical, sonographic and radiological investigations,we found large peritendinous calcifications ventral to the intact heel tendon up to 36 mm in diameter. After operative resection of the calcifications and postoperative chemical prophylaxis, the patient has been without pain for 1 year. There was no relapse of the calcifications or re-rupture of the tendon.

Achilles Tendon↗

PubMed2003

[Minimal invasive cannulated screw osteosynthesis of Bennett's fractures].

PURPOSE OF THE STUDY: The current study presents a new technique and results of minimal invasive screw osteosynthesis in the treatment of Bennett's fractures and discusses its advantages and disadvantages. OPERATIVE TECHNIQUE: The Bennett's fragment has to be of sufficient size (at least one quarter of the articular surface) and closed reduction must be possible to achieve. Temporary fixation by K-wire is followed by minimal invasive osteosynthesis using a cannulated 3.0 mm screw in the lag screw technique. RESULTS: 18 patients underwent minimal screw osteosynthesis, of whom two were lost for follow-up. Average time of follow-up of the remaining 16 patients was 17.2 weeks. Fracture healing was achieved in all of the 16 patients. There were good to excellent results in 13 patients, fair results in one patient and poor results in two patients. CONCLUSION: Good results can be achieved by minimal invasive screw osteosynthesis in the treatment of Bennett's fractures. Correct indications and minute operation technique are indispensable preconditions for this new kind of treatment.

Adult↗

PubMed2003

Autologous chondrocyte implantation and osteochondral cylinder transplantation in cartilage repair of the knee joint. A prospective, comparative trial.

BACKGROUND: Current methods used to restore the joint surface in patients with localized articular cartilage defects include transplantation of an autologous osteochondral cylinder and implantation of autologous chondrocytes. The purpose of this study was to evaluate the clinical and histological outcomes of these two techniques. METHODS: We performed a prospective clinical study to investigate the two-year outcomes in forty patients with an articular cartilage lesion of the femoral condyle who had been randomly treated with either transplantation of an autologous osteochondral cylinder or implantation of autologous chondrocytes. Biopsy specimens from representative patients of both groups were evaluated with histological staining, immunohistochemistry, and scanning electron microscopy. RESULTS: According to the postoperative Lysholm score, the recovery after autologous chondrocyte implantation was slower than that after osteochondral transplantation at six months (p < or = 0.015), twelve months (p < or = 0.001), and twenty-four months (p < or = 0.012). On the basis of the Meyers score and the Tegner activity score, the results were equally good with the two methods two years after treatment. Histomorphological evaluation of biopsy specimens within two years after autologous chondrocyte implantation demonstrated a complete, mechanically stable resurfacing of the defect in all patients. The tissue consisted mainly of fibrocartilage, while localized areas of hyaline-like regenerative cartilage could be detected close to the subchondral bone. Although a gap remained at the site of the transplantation in all five biopsy specimens examined as long as two years after osteochondral cylinder transplantation, histomorphological analysis and scanning electron microscopy revealed no differences between the osteochondral transplants and the surrounding original cartilage. CONCLUSIONS: Both treatments resulted in a decrease in symptoms. However, the improvement provided by the autologous chondrocyte implantation lagged behind that provided by the osteochondral cylinder transplantation. Histologically, the defects treated with autologous chondrocyte implantation were primarily filled with fibrocartilage, whereas the osteochondral cylinder transplants retained their hyaline character, although there was a persistent interface between the transplant and the surrounding original cartilage. Limitations of our study included the small number of patients, the relatively short (two-year) follow-up, and the absence of a control group.

Adolescent↗

PubMed2002

["Biorigid" interlocking after unreamed intramedullary nailing of tibial shaft fractures].

Between April 1996 and December 1999, 76 tibial shaft fractures were treated at the Department of Trauma Surgery of the Justus-Liebig-University in Giessen, Germany and the Department of Orthopedic Surgery of the University of Louisville, USA with a newly developed, unreamed, solid, small diameter tibial nail interlocked "biorigidly" with screws in grooves of the nail. 69 Patients were reviewed with a minimal follow-up period of 16 months. In 65 patients, the fractures united without exchange nailing, although four of these fractures showed a delay of healing. In further four cases, non-union occurred, one of which was associated with the only break of a nail located at a distal interlocking groove of the nail. In one patient, a late medullary infection so far has not recurred following treatment. In 358 implanted interlocking screws, no implant failure was observed. First clinical experience suggests that, especially due to the low rate of material fatigue, the biorigid nail is an alternative to other implants for unreamed intramedullary nailing of the tibia.

Adolescent↗

PubMed2002

[Long-term results in the surgical treatment of pilon tibial fractures. A retrospective study].

BACKGROUND: While Pilon fractures of the tibia have been treated for decades by primary open reduction and internal fixation by plate osteosynthesis, during the last 10 years differential treatment was developed: After primary open reduction nowadays patients are treated with (according to type of fracture and tissue damage). As well as primary open reduction and internal fixation a two-step treatment (primary external fixator and delayed ORIF) or consolidation by external fixator combined with minimal invasive osteosynthesis (cannulated screws and K-wires) has been implemented. Furthermore, the significance of primary bone grafting in comminuted fractures to prevent aseptic pseudarthrosis has been acknowledged. METHODS: Of 151 patients with 160 pilon fractures treated from January 1979 to May 1995, 107 patients (113 fractures) were evaluated. Only the results of C2 and C3 fractures could be compared, as only in these groups were all three types of treatment used. RESULTS: Over 75% of the treated fractures were closed fractures, most of them being fractures with a soft tissue damage grade 2 of the Oestern and Tscherne classification. In the open fractures we found mainly grade 3 fractures according to the Gustilo and Anderson classification. In 54.9% of all pilon tibial fractures we observed an uncomplicated course of healing. Early complications (25.7%) were mainly soft tissue infections, whereas we found pseudarthrosis to be the most frequent late complication. Highest infection rate (55.5%) was in the two-step treatment group (primary external fixator and delayed ORIF) and lowest in the primary internal stabilization group, although especially in the C2 and C3 fractures best clinical late results were obtained with the two-step procedure. CONCLUSION: The complication rate in the treatment of pilon fractures depends mainly on the type of fracture, the soft tissue damage and the type of treatment. The results of primary ORIF varied. In the case of low-grade soft tissue damage, good to excellent results were accomplished. In the case of higher-grade soft tissue damage, the problem of soft tissue coverage and reconstruction of the joint surface could be solved with good results by the two-step treatment. Herewith it is important to use limited open reduction of displaced fragments and fixation by cannulated screws and K-wires. We consider ORIF of the fibula necessary as stabilization of the second column of the ankle joint.

Adolescent↗

PubMed2001

[Correction of malunited distal radius fractures by osteotomy and interposition of iliac crest bone spain in the radio-palmar position. A retrospective study of 42 patients].

The retrospective study included 42 patients who have been treated with a palmar opening wedge osteotomy after malunion of distal radius fracture. 31 patients could be reexamined clinically and radiologically. The corrective osteotomy on the distal radius was done only radiopalmar with an insertion of a corticocancellous iliac graft. Radiological and functional findings as well as the subjective judgement of the patient have been commented pre- and after surgically according to the assessment scheme of Pechlaner and were then compared with the contra lateral wrist. The evaluation of the x-ray pictures showed an improvement from 3.7 to 1.9 points, the functional improvement from 3.7 to 2.6 points. The improvement of the subjective complaints results in a diminution of 3.3 to 2.2 points.

Adult↗

PubMed2001

[A benign form of osteopetrosis. Case report].

Osteopetrosis is a disease in which a disturbance in the resorption of bone formed by endochondral ossification takes place. The cause of the osteoclast insufficiency is unknown. In the literature, the etiology of the disease is discussed in relation to the complete absence of cathepsin K synthesis, a cysteine protease. In our case report, we demonstrated cathepsin K expression in the osteoclast cells of the benign form of osteopetrosis. We also found the macrophage marker CD 68 in these osteoclast cells, whereas other mononuclear phagocytic cells were not present in the vicinity of osteoclasts. The inhibition of osteoclast cells by phagocytes is unlikely.

Antigens, CD↗