Edge transport at the boundary between topologically equivalent lattices.

Edge currents of paramagnetic colloidal particles propagate at the edge between two topologically equivalent magnetic lattices of different lattice constant when the system is driven with periodic modulation loops of an external magnetic field. The number of topologically protected particle edge transport modes is not determined by a bulk-boundary correspondence. Instead, we find a rich variety of edge transport modes that depend on the symmetry of both the edge and the modulation loop. The edge transport can be ratchet-like or adiabatic, time or non-time reversal symmetric. The topological nature of the edge transport is classified by a set of winding numbers around bulk fence points extended by winding numbers around edge specific bifurcation points that cannot be deduced from the two bulk lattices.

Lattice symmetries and the topologically protected transport of colloidal particles.

The topologically protected transport of colloidal particles on top of periodic magnetic patterns is studied experimentally, theoretically, and with computer simulations. To uncover the interplay between topology and symmetry we use patterns of all possible two dimensional magnetic point group symmetries with equal lengths lattice vectors. Transport of colloids is achieved by modulating the potential with external, homogeneous but time dependent magnetic fields. The modulation loops can be classified into topologically distinct classes. All loops falling into the same class cause motion in the same direction, making the transport robust against internal and external perturbations. We show that the lattice symmetry has a profound influence on the transport modes, the accessibility of transport networks, and the individual transport directions of paramagnetic and diamagnetic colloidal particles. We show how the transport of colloidal particles above a two fold symmetric stripe pattern changes from universal adiabatic transport at large elevations via a topologically protected ratchet motion at intermediate elevations toward a non-transport regime at low elevations. Transport above four-fold symmetric patterns is closely related to the two-fold symmetric case. The three-fold symmetric case however consists of a whole family of patterns that continuously vary with a phase variable. We show how this family can be divided into two topologically distinct classes supporting different transport modes and being protected by proper and improper six fold symmetries. We discuss and experimentally demonstrate the topological transition between both classes. All three-fold symmetric patterns support independent transport directions of paramagnetic and diamagnetic particles. The similarities and the differences in the lattice symmetry protected transport of classical over-damped colloidal particles versus the topologically protected transport in quantum mechanical systems are emphasized.

The own experience in femoral bone metastases treatment.

Background. The objective of this paper is an efficacy analysis of surgical treatment of femoral bone cancer metasases depending on surgical technique and tumor localisation.
Material and methods. 144 patients who underwent surgery in 1996-2002 were assesed. In 32 patients with proximal femur matastases tumor resection and angled plate stabilisation was made, 68 patients underwent THR.
In 20 patients with tumor situated in femoral shaft an intramedullary nailing was performed and the rest 14 patients were treated with plate (AO/ASIF) technique. In 10 patients with distal femoral metastases an angled condylar plate was used.The average follow-up time was 6 months.
Results. The surgery outcome was assesed by functional Enneking test. The cases with proximal femur metastases were assesed by Merle d'Aubigne classification. In cases after resection and subsequent THR very good results were found in 5 patients,good in 34, fair in 23 and bad in 6 patients according to Enneking scale. In Merle d'Aubigne classification the results were as follows:very good in 6, good in 30, fair in 26 and bad in 6 patients.
In the intramedullary nailing group the limb function was found good in 17, in 1 fair and bad in 2 patients. The limb function in patients who were operated using plate condylar or stright(AO/ASIF) plate technique was found fair.
Conclusions. The high patients satisfaction and high ratio of good and very good results in tests after modular THR(proximal femur metastases)and after intramedullary nailing(femoral shaft pathology)are methods of choice in those cases. AO plate stabilisation combined with bone cement augmentation is suitable for pathological fractures management.

The surgical manegement of metastases to humerus-clinical evaluation.

Background. The humerus is a common localisation of cancer metastases. The restoration of anatomical order and tumor resection within humerus is important for patients quality of everyday life and for their pain relief. The surgical treatment is one of the most important part of the whole oncological ways of tratment.
The study objective was a clinical assesment of tumor resection and reconstruction within humerus according to matastasis localisation and the choice of surgical technique.
Material and methods. In the years 1999-2002 19 patients underwent surgery due to pathological fracture or/and cancer metastasis within humerus. The shaft localisation of the tumor was found in 8 cases and in 11 patients the metastatic foci were found in proximnal diaphysis. In patients with proximal diaphysis localisation of the tumor the partial resection with subsequent joint exchange procedure was made. The humeral shaft metastatic cancer changes were treated by the segmental resection with subsequent surgical cement filling or auto/allogenical bone grafting combined with intramedullary nail or AO/ASIF plate stabilisation. The average follow-up period was 8,5 months.
Results. In patients after resection with shoulder joint alloplasty according to the Enneking test a very good result was found in 7 and very good in 4 cases.
In patients with femoral shaft metastatic tumor locaslisation, 6 good and 2 fair results were found. In 1 patient after 2 months rehabilitation a reoperation was needed due to the mechanical destabilisation. The best results were found in patients after intramedullary nailing.An acute soft tissue inflamation requiering surgical treatment was found in 1 patient after shoulder joint replacement.
Conclusions. After clinical analysis of the material we highly recomend the partial humeral bone resection with subsequent shoulder alloplasty in patients with proximal humeral diaphysis metastatic localisation. In cases with shaft localisation a better results were found after intramedullary nailing compared to common plate technique.

The efficacy analysis of partial bone resection procedure in pathological fractures treatment (own experience).

Background. The objective of this paper is efficacy assesment of partial bone resection procedure with subsequent joint exchange as a method of skeletal cancer metastases and pathological fractures surgical treatment within hip and shoulder among patients in our own experience.
Material and methods. 79 patients operated between 1997 and 2002 were assesed.Group I - 68 cases with sceletal cancer metastases and pathological fracture of proximal femur.Group II - 11 patients with sceletal cancer metastases and pathological fracture of humerus.The patients underwent primary or secondary (after complications) partial resection procedure with subsequent joint prosthesis implantation.The range of femur resection was 6-17cm.Various types of total or partial hip and shoulder joint endoprostheses according to indication were used.Additional paliative radiotherapy of mathastases,bisphosphonians and analgetics were used according to the case.The average follow-up period was 9,6 months (0-3y). The efficacy analysis was based on Enneking limb function test and Merle d'Aubigne classification and X-ray analysis in patients with partial proximal femur resection.
Results. Group I-according to Enneking test in 41 patients very good and good results,fair in 22 and bad only in 5 cases were found.According to Merle'd Aubigne classification in 37 cases very good and good outcome was found.In 25 the outcome was fair and bad in 6 patients.The machanical instability complication assesed radiologically were found in 7 patients.
Conclusions. The partial bone resection with subsequent joint exchange procedure is positively assesed in patients subjective opinion and its high rate of very good and good results let us conclude this kind of surgery as a very good method in some types of pathological fracture treatment.However a massive bone and particullary soft tissue resection may produce higher incidence of mechanical complications - especially dislocations.