Biomedical subjects

M Schieker

Publications and source records attributed to M Schieker.

10 recordsLinked to original sources

PubMed2006

[Bridging posttraumatic bony defects. Established and new methods].

Bony defects as a result of injury or disease can be caused by a variety of conditions such as acute injury, fall fractures in osteoporotic patients or tumours and congenital malformations of the musculoskeletal system which necessitate the resection of affected parts of the bone. This results in a multitude of defects concerning localisation and specificity as well as a number of conditions involving both hard and soft tissue structures and various situations of different patients. A reasonable classification of defects which is relevant for practical purposes includes four basic types: defects of the spine, metaphyseal defects as well as partial and complete diaphyseal defects of long bones. A variety of options exists for the treatment of these conditions. The aim of all efforts is to reinstall the integrity of affected structures long-lastingly and dependably and at the same time guarantee the normal function of joints involved. In addition to classical treatment strategies which involve the use of autogenous and allogenous corticocancellous bone grafts a great number of bone substitute materials can also be used. Further options lie in complex reconstructive methods such as the transport of whole segments or the transplantation of vascularised bone grafts. The field of new regenerative strategies including tissue engineering as well as stem cell and gene therapy holds great promise for the future. The aim of this review is to derive a ranking from the evaluation of biological and mechanical characteristics for the treatment of posttraumatic defects.

Bone Morphogenetic Proteins↗

PubMed2006

A novel surgical technique for transverse sternal bone defects using flexible intramedullary nailing.

Transverse sternal bone defects as a result of surgery or trauma remain an important clinical condition with serious sequelae. Patients sometimes complain of local pain during movement and breathing. Usually, defects are filled with prosthetic materials which remain permanently IN SITU. Small defects can be treated with autogenous bone grafts, whereas large defects are difficult to stabilize with common osteosynthetic techniques. Here, we report a new surgical technique using flexible intramedullary nailing ("Elastic Stable Intramedullary Nailing"--ESIN or "Embrochage Centro-Medullaire Elastique Stable"--ECMES) to stabilize a sternal defect after surgical removal of an osteochondral lesion. The defect was bridged by two elastic titanium nails and an autogenous corticocancellous bone graft. This new surgical technique showed a good clinical and functional outcome.

Adult↗

PubMed2005

[Anterior dislocation of the shoulder--a reduction technique that is easy on the patient].

Modified scapula manipulation represents a simple, highly successful and--both for the physician and the patient--pleasant new reduction technique in cases of anterior dislocation of the shoulder. The advantages of this technique--in particular in comparison with the previously employed methods are well founded. Non-evaluated methods, which are fraught with complications, such as the Hippocrates' method, should no longer be applied.

Adolescent↗

PubMed2005

[Complete rupture of the proximal semimembranosus tendon. Minimally invasive surgical repair by use of a suture anchor in a rare but often underestimated injury].

Complete rupture of the proximal semimembranosus tendon is a rare injury associated with significant functional loss. Conservative treatment has proven inadequate in returning patients to their previous activity level. However, diagnosis is often delayed because of underestimation of the severity of this injury. Satisfactory results can be achieved with both early and late surgical tendon repair in the majority of cases. However, repair delayed by more than 4 weeks post trauma usually requires extended mobilisation of the injured muscle and neurolysis of the sciatic nerve. Therefore, we recommend surgical repair as early as possible. We report on the successful minimally invasive surgical repair of a complete rupture of the proximal semimembranosus tendon by use of a suture anchor 18 days after injury.

Bone Screws↗

PubMed2005

[New-bone formation by osteogenic protein-1 and autogenic bone marrow in a critical tibial defect model in sheep].

AIM: Osteogenic Protein-1 (OP-1) is known to be a very potent osteoinductive growth factor. However, experimental studies using critical-size defect models in the weight-bearing lower extremity show non-uniform results. Therefore, we studied the osteoinductivity of OP-1 in a tibial worst-case defect model in sheep. Potential improvement of OP-1 induced new bone formation using a composite graft with autogenous bone marrow was to be investigated. METHOD: In 19 sheep a 5 cm segmental defect of the tibial diaphysis was treated by intramedullary nailing and filled with the following implants: 5 mg OP-1 + inactivated demineralized bone matrix (group 1; n = 6); 5 mg OP-1 + inactivated demineralized bone matrix + 5 ml autogenous bone marrow (group 2; n = 5); autogenous cancellous bone (group 3; n = 4), or inactivated demineralized bone matrix + 5 ml autogenous bone marrow (group 4; n = 4). RESULTS: In total, 3 out of 10 defect sites treated with OP-1 were completely bridged radiographically by 12 weeks. Initially, x-rays showed accelerated new bone formation by use of the composite grafts containing OP-1 and autogenous bone marrow. However, 12 weeks post surgery 3D-CT-volumetry could not detect significant differences of new bone formation within the defect sites treated by OP-1 with or without bone marrow, while new bone formation by autogenous cancellous bone was better than by OP-1. CONCLUSION: In our worst case defect model, the osteoinductive potential of OP-1 is initially accelerated but 12 weeks post surgery not increased when combined with autogenous bone marrow transplantation. So far, critical segmental bone defects of the weight-bearing lower extremity can not be bridged regularly in our model by use of OP-1. Therefore, for the treatment of such critical defects with rotational instability the examined application device of OP-1 can not yet be recommended.

Animals↗

PubMed2004

[Telomerase activity and telomere length of human mesenchymal stem cells. Changes during osteogenic differentiation].

Human mesenchymal stem cells (hMSC) exhibit properties of self-renewal and differentiation. Assuming that telomerase activity is associated with self-renewal, it might be useful to identify and define hMSC on the basis of their telomerase status. However, telomerase activity in hMSC remains a controversial issue. Therefore, the aim of our study was to investigate telomerase activity in proliferating and highly proliferating hMSC and to measure telomerase activity and changes in telomere restriction fragment (TRF) length of confluent hMSC and of osteogenically differentiated hMSC. For tissue engineering applications scaffolds should be seeded with cells that have not lost their ability to self-replicate and differentiate during in vitro cell culture. Telomerase activity could be used to characterise and isolate these cells.

Cell Differentiation↗

PubMed2004

[Tissue engineering of bone. Integration and migration of human mesenchymal stem cells in colonized contructs in a murine model].

Tissue engineering opens up new ways for therapy of bone defects. Therefore, the aim of this study was to establish a mouse model to investigate local cell growth of human mesenchymal stem cells (hMSC) on the scaffold in vivo. Moreover, migration of cells to other organs should be excluded.hMSC (Cambrex, USA) were cultivated according to supplier's recommendations. After inoculation on cylindric scaffolds, one matrix cell construct and one scaffold without hMSC were implanted subcutaneously left and right paravertebrally in athymic nude mice. After 2, 4, 8, and 12 weeks constructs and organs were harvested for immunohistological evaluation and PCR. In conclusion, we found integration of scaffolds loaded with hMSC implanted ectopically. HMSC seeded on 3D scaffolds survived for a period of up to 12 weeks. In addition, we could not detect hMSC in any other organ of the host.

Animals↗

PubMed2004

Molecular composition and pathology of entheses on the medial and lateral epicondyles of the humerus: a structural basis for epicondylitis.

OBJECTIVES: To improve the understanding of epicondylitis by describing the normal structure and composition of the entheses associated with the medial and lateral epicondyles and their histopathology in elderly cadavers. METHODS: Medial and lateral epicondyles were obtained from 12 cadavers. Six middle aged cadavers (mean 47 years) were used to assess the molecular composition of "normal" entheses from people within an age range vulnerable to epicondylitis. Cryosections of epicondylar entheses were immunolabelled with monoclonal antibodies against molecules associated with fibrocartilage and related tissues. A further six elderly cadavers (mean 84 years) were used for histology to assess features of entheses related to increasing age. RESULTS: Tendon entheses on both epicondyles fused with those of the collateral ligaments and formed a more extensive structure than hitherto appreciated. Fibrocartilage (which labelled for type II collagen and aggrecan) was a constant feature of all entheses. Entheses from elderly subjects showed extensive microscopic damage, hitherto regarded as a hallmark of epicondylitis. CONCLUSIONS: Fibrocartilage is a normal feature and not always a sign of enthesopathy. Furthermore, pathological changes documented in patients with epicondylitis may also be seen in elderly people. The fusion of the common extensor and flexor tendon entheses with those of the collateral ligaments suggests that the latter may be implicated as well. This may explain why pain and tenderness in epicondylitis may extend locally beyond the tendon enthesis and why some patients are refractory to local treatments.

Adult↗

PubMed2002

An immunohistochemical study of the rabbit suprapatella, a sesamoid fibrocartilage in the quadriceps tendon containing aggrecan.

The rabbit suprapatella is a sesamoid fibrocartilage in the deep surface of the tendon of vastus intermedius and an integral part of the knee joint. We report the presence of a variety of proteoglycans (aggrecan and versican), glycosaminoglycans (chondroitin 4 and 6 sulfate, dermatan sulfate, keratan sulfate) and glycoproteins (tenascin) in its extracellular matrix and the intermediate filament vimentin in the fibrocartilage cells. The most significant finding is the presence of aggrecan in the extracellular matrix, along with its associated link protein and several of its integral glycosaminoglycans. Aggrecan probably enables the suprapatella to withstand compression. Although it can be assumed that aggrecan metabolites detected in synovial fluid from some human joints are predominantly associated with articular hyaline cartilage, the presence of aggrecan in the rabbit suprapatella means that this cannot be assumed for all animal knee joints. We conclude that it is important for orthopedic researchers who use animal models for arthritis research to check for the presence of a suprapatella when joint fluid analyses are interpreted.

Aggrecans↗

PubMedDate not supplied

[3D-Culturing of human osteoblastic cells with vessel like nutrient supply].

AIM: The treatment of large, critical-size bone defects is a major therapeutic problem in orthopaedic and reconstructive surgery. The engineering of bone tissue could be used to replace lost bone mass. However, scaffolds seeded with vital cells and cultured in vitro suffer from poor oxygen and nutrient supply centrally, when the constructs exceed a critical volume. Therefore, we have established an osteoblastic cell culture in a new 3D-culture chamber with an artificial, vessel-like central membrane, allowing continuous nutrient supply. METHOD: Human osteoblasts were cultured in a 3D-like manner using a perfusion chamber for one week. In this system, the nutrient supply is guaranteed by a vessel-like, semipermeable polysulfone membrane with a continuous flow of medium. After fixation and cryosectioning, histological and immunohistological staining and scanning electron microscopy was carried out. RESULTS: Examinations reveal 3D cell growth around the central vessel. Formation of an extracellular matrix, rich in collagen type I and fibronectin, was detected immunohistochemically. Furthermore, we demonstrated cell adherence to the membrane and examined the surface morphology by scanning electron microscopy. CONCLUSION: The innovative approach for 3D-culturing of human osteoblasts in a system with a central nutrient supply opens up new possibilities for the in vitro cultivation for tissue engineering.

Cell Culture Techniques↗