Human osteoblastic cells were grown in a three-dimensional (3-D) cell culture model and used to test the effects of a 20 Hz sinusoidal electromagnetic field (EMF; 6 mT and 113 mV/cm max) on collagen type I mRNA expression and extracellular matrix formation in comparison with the effects of growth factors. The cells were isolated from trabecular bone of a healthy individual (HO-197) and from a patient presenting with myositis ossificans (MO-192) and grown in a collagenous sponge-like substrate. Maximal enhancement of collagen type I expression after EMF treatment was 3.7-fold in HO-197 cells and 5.4-fold in MO-192 cells. Similar enhancement was found after transforming growth factor-beta (TGF-beta) and insulin-like growth factor-I (IGF-I) treatment. Combined treatment of the cells with EMF and the two growth factors TGF-beta and IGF-I did not act synergistically. MO-192 cells produced an osteoblast-characteristic extracellular matrix containing collagen type I, alkaline phosphatase, and osteocalcin, together with collagen type III, TP-1, and TP-3, two epitopes of an osteoblastic differentiation marker. The data suggest that the effects of EMFs on osteoblastic differentiation are comparable to those of TGF-beta and IGF-I. We conclude that EMF effects in the treatment of skeletal disorders and in orthopedic adjuvant therapy are mediated via enhancement of collagen type I mRNA expression, which may lead to extensive extracellular matrix synthesis.

Complications associated with spinal metastases encompass not only pain, but often neurological deficits and possibly even paralysis due to transverse lesions. The differential indication for dorsal, ventral and combined surgical procedures depends on the nature and extent of the tumor, and the life expectancy and general state of health of the patient. Surgery must be carried out in good time, before additional damage to the spinal cord occurs. In recent years, 20 patients have been treated by GHG-vertebral body replacement. In 19 of these patients, pain was considerably improved. All patients were able to walk following surgery. Preoperative neurological deficits disappeared, in 9 of 13 patients resulting in a major improvement in the patients' quality of life.

When bovine articular cartilage was incubated in Ringer's solution, considerable amounts of proteoglycan were washed out of the cartilage. Thus, 4% of the proteoglycan was lost into the medium during an incubation of 4 hours. Subsequently, it was found that ionic aqueous media like saline or Ringer's solution extracted much more proteoglycan than ion-free media like distilled water or a variety of carbohydrate containing solutions. In separate experiments, it could be shown that solutions of 20% sorbitol and 2% mannitol exhibited particularly low proteoglycan extracting properties. It was found that the extraction of proteoglycan was dependent on the ion concentration in the aqueous media. The extraction of proteoglycan by sodium chloride was negligible at NaCl concentrations of 0.1% and lower. Proteoglycan loss from cartilage was only induced at 0.9% NaCl. Using intact rat femoral heads it could be shown that the elution of proteoglycan from cartilage occurred as well when the cartilage was intact. Here, the elution occurred at a slower rate but the differences between ionic and ion-free solutions were greater. By electronmicroscopic examination of bovine cartilage incubated in different media, it was observed that Ringer's solution induced a more uneven and rougher appearance of the cartilage surface than did 10% mannitol solution, indicating that probably a denudation of collagen fibers occurs on the loss of proteoglycan from the cartilage. Because the observed proteoglycan washout occurred within rather short periods of contact of the cartilage with the medium, it is concluded that this may be of relevance for the clinical situation during arthroscopic procedures. The use of preferably isotonic carbohydrate solutions like 5% mannitol is suggested to prevent unnecessary loss of proteoglycan from hyaline cartilage.

Cemented cups in the young patient continue to show an unacceptable rate of early aseptic loosening. A well designed cementless prosthesis, implanted with good technique, is a better alternative. With the uncertainty surrounding the femoral stem, a hybrid total hip with a cemented stem and porous ingrowth cup remains an acceptable interim solution. There is an ongoing problem with the wear debris produced by the available implant materials. There is hope that the newer materials will help in this regard. Custom made prostheses at this time, seem most suited for those hips with marked deformity making the use of standard systems difficult. The use of cement in the elderly population remains an acceptable technique with the advantages of immediate fixation and early weight bearing.

Advantages and disadvantages of various fixation procedures for use in fractures of the femoral neck--blade-plate with temporary fixation by means of Kirschner wire insertion or dynamic hip screws--and hemi- or total allo-arthroplasty are described. The large number of fixation procedures for pertrochanteric fractures reflects the difficulty in achieving mobility and loading stability. On account of the possible intra- and postoperative complications, the highly propagated gamma nailing has proved problematic. Overall, the individual situation of the patient must be taken into account when choosing the appropriate fixation procedure.

The authors present an account of a group of 51 patients to whom an individual endoprosthesis of the knee joint was implanted on account of a tumour. A primary bone tumour was involved in 42 cases and a metastatic process in 9 cases. Twenty-four endoprostheses were cemented, 26 were implanted without cement. The mean follow-up period was 43 months. Functional results excellent and good in 61%, poor results only in 5%.

We show two case reports to discuss the problem of fatigue fractures of non-cemented porous coated total hip prosthesis. Fatigue fractures occur in the region of highest tensile stresses. Because of the surface irregularities of the porous coating, tensile stresses in the surface of the stems are increased depending on the configuration of the pore. A thick porous coating also decreases the cross section of the stem. In addition the manufacturing process, the application of a porous layer can weaken the stem. Finally, cementless prostheses are implanted especially in young active patients, who exert high forces on their hip. For cementless porous coated hip prostheses, we need a standardized manufacturing process and test of the fatigue strength. In addition, there should be a minimum diameter of the core of the stem in order to avoid fatigue fractures. Key words: porous coated total hip prosthesis, fatigue fracture of the stem.

Most authors associate avascular necrosis of the femoral head with ischemia, caused by injuries or diseases of the nutrient vessels or by alteration of the hemorheology. We examined the rheological properties of the blood in 39 patients with nontraumatic avascular necrosis of the femoral head by following tests: viscosimetry, filtrometry and aggregation of red blood cells. Aggregation of red blood cells showed statistically significant pathologic alterations. Our results confirm that irreversible agglutination phenomenons followed by ischemia can be caused by 1. stenosis or obliteration of nutrient vessels 2. rheologic alterations of the blood.

Since the introduction of more effective adjuvant therapies in the area of primary and secondary bone tumors, limb salvage procedures have become more and more important. At the Orthopedic Department of the Technical University, Munich, 52 special knee prostheses have been implanted in patients with malignant tumors of the distal femur and proximal tibia. On the basis of the ISOLS criteria, the functional results achieved were excellent in 14%, good in 47%, satisfactory in 35%, and poor in only 5% of patients after an average follow-up period of 43 months (range: 3-156 months). The perioperative complication rate was 27%, and late complications were material fatigue and wear. In the case of primary tumors, a customized prostheses, and in the case of secondary tumors a modular system is recommended. Individual treatment planning is essential.

It appears that tuberculous spondylitis is becoming more common again-also in Germany. In the present case report, the clinical picture, diagnosis and treatment of this condition are discussed. Clinical findings, in combination with radiological examinations, CT and MRI enable an early diagnosis to be established. This is of decisive importance if extensive destruction and axial deformities of the spine with resulting pareses are to be prevented.

To date, our ongoing prospective study of more than 6 years duration has documented and analyzed 113 injuries sustained by squad players who had participated in a total of 323 international games. In the case of the upper limb, injuries to the hand and shoulder predominate (34.5%), while in the lower limb the knee joint and foot (38.9%) are most frequently involved. Despite a decrease in the number of injuries--the present incidence of injuries among senior players is 56.7%, and among junior players 59.1%--such preventive measures as checking and improving proper protective equipment must constantly be re-evaluated and discussed. Today, in the case of squad players, injuries are sustained to the non-use of (full- or half-vizor helmets) or deficient equipment (modifications made in favor of comfort). In this type of team sport, speed and body contact are an integral part of the game, and this is associated with an increased risk of injury. In general terms, an important preventive measure to be demanded in national and international standardization of the player's entire equipment.

Despite 3D gradient echo technique has a better spacial resolution than spin echo sequences, 3D imaging is not well accepted for clinical routine. Because of the large amount of data evaluation cannot be done by single photo-documented slices. Postprocessing of the 3D data sets with an image analysis system is indispensable. A maximum of two different gradient echo sequences (FLASH, FISP) are necessary for imaging of the whole interesting volume with continuous slices. Time of examination is shorter (16 resp. 32 minutes) compared with conventional spin echo sequences. In our opinion 3D gradient echo-sequences are a reliable noninvasive technique for the evaluation of pathological changes of the knee joint which could replace diagnostic arthroscopy in the future.

Mit Hilfe der Autoradiographie (S35) wurde die Vitalität osteochondraler Transplantate nach Konservierung in verschiedenen Temperaturbereichen (- 20 °C, - 70 °C, - 196 °C) unter Anwendung von Gefrierschutzlösungen und unterschiedlichen Lagerungszeiten (bis 3 Monate) überprüft. Ungeachtet der Gefriertechnik sind alle kältekonservierten Transplantate avital, was durch die fehlende Aufnahme von S35 bewiesen wird. Dies scheint die hauptsächliche Ursache der arthrotischen Veränderungen von Transplantat und Wirtsgewebe zu sein, vor allen Dingen wie sie bei mittelfristigen und Langzeitbeobachtungen im Experiment gefunden werden.

Article Mössbauer and Perturbed Angular Correlation Studies of the Distribution and Diffusion of Hydrogen Near Impurities in Metal Hydrogen Systems* was published on January 1, 1985 in the journal Zeitschrift für Physikalische Chemie (volume 145, issue 1-2).

Mössbauer experiments with the 90 keV resonance of99Ru as well as PAC measurements using the 353 and 528 keV - 90 keV cascades in99Ru and the 84 keV - 75 keV cascade in100Rh were combined in a study of the hyperfine interactions produced by the hydrogen distribution near Ru, Rh and Pd atoms in Β-PdHx (0.6≲x≲1.0). The electric field gradients produced by the non-cubic nearest neighbour hydrogen distribution were found to be very small. This shows that the protons are very strongly shielded and justifies an interpretation of the Mössbauer spectra in terms of isomer shift distributions only. By combining the two methods one thus can obtain a rather detailed picture of the hydrogen distribution near the probe atoms.