We assessed narrowing of the spinal canal in 39 burst fractures and fracture-dislocations of thoracolumbar vertebrae treated by the AO Internal Spinal Fixator, using CT preoperatively and at various stages postoperatively. Computer-aided planimetry was used to measure the narrowing, and its restoration shortly after instrumentation, or at 15 months. The mean initial reduction of canal area was to 63.7% +/- 18.8% of normal; this was restored to a mean of 95.4% +/- 21.2% of normal when measured either soon after surgery or at 15 months (p < 0.001 for both groups). There was more improvement in cases assessed later. For fractures from D12 to L3, the mean canal area was restored to 99.4% of normal; but at L4 or L5 the mean restitution was to only 60.9% (p < 0.05). We found no correlation between preoperative loss of area and amount of restoration, or severity of neurological deficit. Nor was there any correlation between the delay before surgery and the improvement achieved. The mechanism of fracture reduction appears to be a combination of distraction ligamentotaxis and forced hyperextension.

167 patients with fracture dislocations of the proximal humerus--operated upon between 1970 and 1980--were followed up on an average 43.2 months after the accident. Fractures were classified according to Neer in two-part-(n = 24), three-part-(n = 60) and four-part-fractures (n = 61) as well as fractures of the articular surface (n = 21). 20.4% of all fractures were complicated by a neurological lesion. In 31% of all cases a good or excellent result was obtained. The functional result and the rate of avascular head necrosis were dependent on the type of fracture, that means the number of displaced parts. Results after 23 head prostheses were disappointing. The analysis of functional results and the rate of avascular head necrosis after different types of operation proved that minimal fixation with K-wire or tension-band was slightly superior to plate fixation.

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Adult hippocampal neurogenesis has been implicated in hippocampus-dependent learning and memory. Furthermore, the decline of neurogenesis accompanying aging could be involved in age-related cognitive deficits. It is believed that the neural stem cell niche comprises a specialized microenvironment regulating stem cell activation and maintenance. However, little is known about the significance of the extracellular matrix in controlling adult stem cells. Reelin is a large glycoprotein of the extracelluar matrix known to be of crucial importance for neuronal migration. Here, we examined the local interrelation between Reelin expressing interneurons and putative hippocampal stem cells and investigated the effects of Reelin deficiency on stem cell and progenitor cell proliferation. Reelin-positive cells are found in close vicinity to putative stem cell processes, which would allow for stem cell regulation by Reelin. We investigated the proliferation of stem cells in the Reelin-deficient reeler hippocampus by Ki67 labeling and found a strong reduction of mitotic cells. A detailed analysis of dividing Type 1, type 2 and type 3 cells indicated that once a stem cell is recruited for proliferation, the progression to the next progenitor stage as well as the number of mitotic cycles is not altered in reeler. Our data point to a role for Reelin in either regulating stem cell quiescence or maintenance.

Infections of the knee joint have to be considered as emergency cases. They must be treated by immediate surgical intervention. Otherwise irreversible cartilage lesions will occur already after one week. An immobilization decreases the exchange of substrates within the knee joint and impedes the resistance to infections. An early functional follow-up treatment should be performed. The therapy conception resulting from these considerations includes a lavage and following continuous passive mobility therapy on a motor bar. This method has proved successful during the last years and led to clearly improved results.

Implanted bovine apatite is highly osteoconductive, since it serves the host tissue as a "guide-line" for the deposition of newly developing bone tissue. It is well tolerated, but it showed no signs of being resorbed during the course of the experiment. Previous impregnation of the bovine hydroxyapatite with a low molecular humate substance obviously encourages its resorption. This is most easily explained by the known ability of humate to induce the activation of leucocytes. The occasional over-resorption of the apatite is dependent (1) upon the preparation of the implant (granulate) and (2) the local concentration of the humate. Future research is being directed towards the production of a satisfactorily usable form of humate and apatite and the investigation of its HIV blocking action on heterologous cancellous bone.