Anomalous Composition-Induced Crossover in the Magnetic Properties of the Itinerant-Electron Antiferromagnet Ca_{1-x}Sr_{x}Co_{2-y}As_{2}.

The inference of Ying et al. [Europhys. Lett. 104, 67005 (2013)EULEEJ0295-507510.1209/0295-5075/104/67005] of a composition-induced change from c-axis ordered-moment alignment in a collinear A-type antiferromagnetic (AFM) structure at small x to ab-plane alignment in an unknown AFM structure at larger x in Ca_{1-x}Sr_{x}Co_{2-y}As_{2} with the body-centered tetragonal ThCr_{2}Si_{2} structure is confirmed. Our major finding is an anomalous magnetic behavior in the crossover region 0.2≲x≲0.3 between these two phases. In this region the magnetic susceptibility vs temperature χ_{ab}(T) measured with magnetic fields H applied in the ab plane exhibit typical AFM behaviors with cusps at the Néel temperatures of ∼ 65 K, whereas χ_{c}(T) and the low-temperature isothermal magnetization M_{c}(H) with H aligned along the c axis exhibit extremely soft ferromagneticlike behaviors.

Short-range ferromagnetic order due to Ir substitutions in single-crystalline Ba(Co1- x Ir x )2As2 (0 ⩽ x ⩽ 0.25).

The ternary-arsenide compound BaCo2As2 was previously proposed to be in proximity to a quantum-critical point where long-range ferromagnetic (FM) order is suppressed by quantum fluctuations. Here we report the effect of Ir substitutions for Co on the magnetic and thermal properties of Ba[Formula: see text] (0 ⩽ x ⩽ 0.25) single crystals. These compositions all crystallize in an uncollapsed body-centered-tetragonal ThCr2Si2 structure with space group I4/mmm. Magnetic susceptibility measurements reveal clear signatures of short-range FM ordering for x ⩾ 0.11 below a nearly composition-independent characteristic temperature T cl ≈ 13 K. The small variation of T cl with x, thermomagnetic irreversibility between zero-field-cooled and field-cooled magnetic susceptibility versus T, the occurrence of hysteresis in magnetization versus field isotherms at low field and temperature, and very small spontaneous and remanent magnetizations <0.01 µ B/f.u. together indicate that the FM response arises from short-range FM ordering of FM spin clusters as previously inferred to occur in Ca(Co1-x Ir x )2-y As2. Heat-capacity C p(T) data do not exhibit any clear feature around T cl, consistent with the very small moments of the FM clusters. The C p(T) in the paramagnetic temperature regime 25-300 K is well described by the sum of a Sommerfeld electronic contribution and Debye and Einstein lattice contributions where the latter lattice contribution suggests the presence of low-frequency optic modes associated with the heavy Ba atoms in the crystals.

[Personal experience with the Grice operation in patients with cerebral palsy]. / Nase zkusenosti s operací podle Griceho u pacientu postizených mozkovou obrnou.

The authors give an account of Grice's operation, i.e. extraarticular, talocalcaneal arthrodesis as one of the basic operations in infantile cerebral palsy in children and adolescents which can be used in the spastic as well as paretic form of the disease. It is valuable as after reposition it stabilizes the position of tarsal bone sub talo. The 65 operations by Grice's method in infantile cerebral palsy with very favourable results (failure or partial failure in five operations, i.e. 9.2%) and the authors' experience with this operations also in other neurogenic disorders indicates that the operation is justified in children and adolescents. It may be performed also in adults. According to the authors' experience this operation does not lead during subsequent development to deformities of the sole and does not merely substitute the well known triple arthrodesis sub talo. Its application is much wider. It can be combined with other surgical procedures on soft parts as well as bones, in particular with Young's operation and with temporary fixation of tarsal bones with Kirschner wires after reposition.

[Our Experience with Stephenson and Donovan's Operation when Dealing with Adduction Contractures in Infantile Cerebral Palsy.]. / Nase zkusenosti s operací podle Stephensona a Donovana pri resení addukcní kontraktury kycle u detské mozkové obrny.

The authors evaluate 39 transpositions of adductors performed by Stephenson and Donovan's procedure in 1970-1992 in patients with infantile cerebral palsy. The authors consider this operation one of the basic ones, along with tenotomy of the adductors, when dealing with muscular disbalance and contractures in the area of the hip joint. Based on long-term experience the authors give the main indication of this operation, i.e. marked inner rotation of the hip associated with moderate adduction. They draw attention to the fact that if the operation is properly indicated, it can influence on a marked way the general posture, standing and gait of patients up to adolescent age. Key words: infantile cerebral palsy, tenotomy of adductors, transposition of adductors.

[Ischaemic Post-dislocation Necrosis of the Head of the Femur: Possibilities of Surgical Treatment Part I: Theoretical Introduction, Conservative and Surgical Treatment.]. / Ischemická postluxacní nekróza hlavice femuru: moznosti chirurgického lécení I. cást: teoretický úvod, konzervativní a chirurgická lécba.

In the submitted part of the paper the authors discuss the theoretical background of the problem - a list of possible complications encountered in treatment of inborn dysplasia of the hip joint, vascularization of the proximal femur, possible early diagnosis of ischaemic necrosis and its criteria, different classifications of ischaemic necrosis (a more detailed account is given of the classification of Hirohashi et al. and Ogden and Buchholz). The authors discuss also possibilities of conservative treatment of ischaemic necrosis and surgical treatment of ischaemic necrosis in general and treatment focused on different aspects of the therapeutic objective - sufficient acetabulum, normal proximal end of femur, congruence of the two components and sufficient pelvifemoral musculature. Key words: congenital dysplasia of the hip joint, ischaemic postdislocation necrosis of the head of the femur, surgical treatment.

[Ischaemic Post-dislocation Necrosis of the Head of the Femur: Possibilities of Surgical Treatment (Part II: Surgical Procedure at the Orthopaedic Clinic in the Faculty Hospital in Motol).]. / Ischemická postluxacní nekróza hlavice femuru: moznosti chirurgického lécení (II. cást: operacní postup na Ortopedické klinice FN Motol).

This part of the paper is based on the theoretical background and principles of conservative and surgical treatment described in part I. The authors describe the principle of operation and give a detailed account of it, supplemented by diagrams. In the discussion the authors mention views regarding the type and scope of surgery with regard to the assumed increased pressure exerted on the head of the femur, and also changes of the ratio of forces in the femur are discussed. Key words: inborn dysplasia of the hip joints, ischaemic necrosis, surgical treatment.

[Hallux Valgus in Cerebral Palsy and Surgery by Author's Modification.]. / Hallux valgus u detské mozkové obrny a jeho operacní resení ve vlastní modifikaci.

The authors present their own surgical procedure used in hallux valgus of spastic origin in cerebral palsy in children and adolescents. In 11 patients they made a plastic operation in the area of the metatarsophalangeal joint by splitting the tendon of the m. extensor hallucis longus by shifting its medial half into the fold of the capsule of this joint on the inner side into the area of the m. abductor hallucis. Favourable postoperative results were recorded between the age of 10 and 14 years. With advancing age the success of the operation declines and other types of surgery should be considered. The described plastic operation is one of the possible solutions of hallux valgus spasticus in junior children, about 10 years old. Key words: cerebral palsy, surgical treatment, hallux valgus spasticus (neurogenes).

[The Strayer surgical technic as the basic operation for treatment of pes equinus in cerebral palsy]. / Operace podle Strayera jako základní operace k ovlivnení pes equinus u detské mozkové obrny.

The authors describe the technique of Strayer's operation (gastrocnemius recession) in the spastic form of cerebral palsy and draw attention to its indications, possible combinations with other operations and technical errors associated with its implementation. They evaluate 644 operations made by Strayer's method. In 361 regularly followed-up patients they evaluate from the long-term aspect combined operations of the lower extremities (which form a functional unit), using as a basis their own locomotor and position standards. They emphasize the necessity of a correct strategy, i.e. selection and sequence of surgical procedures. They recommend Strayer's operation (gastrocnemius recession) as the basic operation in pes equinus spasticus and in genu flectum spasticum. In the conclusion they present their own modification of Strayer's operation elaborated by the first author.

[Genu flectum in cerebral palsy, elongation of the flexors of the knee joint and our modification]. / Genu flectum u detské mozkové obrny (DMO), prolongace flexoru kolenních kloubu s uvedením vlastní modifikace.

The authors evaluate the results of prolongation of the flexors of the knee joint in 175 patients with a flexed position of the knee joint associated with the spastic form of cerebral palsy. They draw attention to the interrelationship of the position of the lower extremities in the area of the sole, knee and hip joint and emphasize the necessity of correct assessment of primary contractures. They emphasize also the evaluation of correct concurrent function of flexors and extensors of the knee and their balanced functioning. The authors prefer a single surgical operation in combined affections of the lower extremities to the system of so-called minor steps. They emphasize the importance of postoperative rehabilitation and prosthetic support. In the authors' opinion surgery of the knee joint in manifestations of cerebral palsy on the lower extremities is the most controversial area associated with the highest percentage of failures and complications. Contrary to data in the literature, they refute the necessity of capsulotomy of the knee joint and recommend their own modification how to treat severe forms of genu flectum spasticum.

[Importance of tenotomy of the adductors in the treatment of cerebral palsy manifestations in the lower extremities]. / Význam tenotomie adduktoru pro lécení projevu detské mozkové obrny na dolních koncetinách.

The authors evaluate 303 tenotomies of adductors performed in patients with cerebral palsy (CP) in 1970-1992. They emphasize the correct diagnosis of adduction contracture of the hip joint and correct treatment, incl. early surgery, not only because of the influence of adductors on standing and gait but also on the development of the hip joint in children. The authors draw attention to the increased incidence of subluxations and luxations of the hip joint in recent years in children with CP who were not operated or where the muscular balance and contractures of the hip joint were not modified. They emphasize the fact that in children where tenotomy of the adductors was performed in time before the age of 8 years, with a single exception luxation did not develop. In the authors' opinion tenotomy at the age of cca 11 years is an essential operation but in view of the development of skeletal changes it is late. The authors recommend to pay increased attention to the problem of adductors in CP as regards diagnosis and technical aspects of the operation.

[Transposition and hemitransposition of the anterior tibial muscle in the treatment of pes equinovarus]. / Transpozice a hemitranspozice musculus tibialis anterior pri resení pes equinovarus.

PURPOSE OF THE STUDY: Authors present transposition and hemitransposition of anterior tibial muscle as one of the supporting surgeries in the treatment of neurogenous but also congenital club foot. MATERIAL: In the period of 30 years they indicated and performed transposition of anterior tibial muscle 79 times in 75 patients and hemitransposition of anterior tibial muscle in 27 patients. Most frequently they used this method in patients with childrens' cerebral palsy, least frequently in patients with congenital club foot. METHODS: The authors prefer hemitransposition of anterior tibial muscle (Biesalski-Mayer) at the younger age and transposition of the whole anterior tibial muscle in children above the age of 9 years and in cases where the foot is more rigid or where bone changes already have developed. From the medial approach they expose the distal origin of the tendon of anterior tibial muscle, separate one or both origins of the tendon in compliance with the nature of the transposition, transpose over a supporting section above the ankle and fix the tendon to base V or IV of the metatarsal. The evaluated group included patients who at the given period attended the control check, i.e. 14 patients after hemitransposition and 45 patients after complete transposition. The shortest interval after the surgery was 9 months. RESULTS: In the evaluated group the authors performed clinical examination and radiograph. They report excellent results in hemitransposition in 57.1% with achieved plantigrade position of the foot and the function of transposed muscle 4 according to the muscle test. In 42.9% of cases the result was good. Similar results they recorded in complete transposition, excellent result in 23 cases (48.9%), good result in 8 patients (38.2%), in 2 patients there occured valgus overcorrection (4.3%), in 8.5% of patients with progressive disease the position subsequently worsened. Radiograph examination showed in the younger age group until the age of 8 years an increased value of the talocalcanear angle. DISCUSSION: By the number of patients, indication and results the evaluated group is comparable with literary data. The authors present reasons for the localization of transposition to Vth or IVth metatarsal in contradiction to biomechanical studies. This operation is not usually indicated as a separate surgery, most often it is performed simultaneously with the operation on m. triceps surrae and operation after Steindler. CONCLUSION: The method of transposition of anterior tibial muscle is recommended by authors mainly in neurogenous club foot where a combined operation on muscles may result in the final remedy of the defect. The method of complete transposition of anterior tibial muscle may be used also in progressive neurogenous diseases with the purpose of postponing resection sub talo.

[A Combination of Young's and Grice's Operation in Pes Planovalgus in Children with Cerebral Palsy.]. / Kombinace operací podle Younga a Griceho pri resení pes planovalgus u detí s detskou mozkovou obrnou.

The authors describe a combination of operations according to Young and Grice, i.e. a combination of suspension of the os naviculare on the anterior tibial muscle for modelling the longitudinal arch of the foot with extraarticular talocalcanear arthrodesis, when dealing with neurogenic deformities of the sole in cerebral palsy in children, and evaluate the results of the operation. In general the authors draw attention to certain changes in the clinical picture of cerebral palsy, in particular a more frequent incidence of deformities of the soles which in recent years shifted from the original age of 6-8 years to the age 4-3 years. The combination of the mentioned operations improves the reposition of the soles and thus the general results of Grice's operation which is basic in deformities of the sole in surgery of celebral palsy. Young's operation can be performed in young children also separately. However, it does not produce permanent results without a secondary Grice's operation. It can be implemented in a second stage. Young's operation cannot be made unless there is a sufficiently strong anterior tibial muscle (at least grade 4 in the muscle test). Thus it cannot be performed in weak pareses. The achieved results (64,9 % excellent, 27,0 % good) fully justify the combination of the above operations. Key words: cerebral palsy (CP), extraarticular talocalcanear arthrodesis, Grice's operation, Young's operation, transposition of the tendon of the anterior tibial muscle across the os naviculare.

[Iliopsoas muscle - one of the causes of neurogenous dislocation: technique of tenotomy and lengthening.]. / Musculus iliopsoas - jedna z prícin neurogenní luxace: vlastní technika a prolongace.

An increased incidence of neurogenous dislocations in patients with infantile cerebral palsy led the authors mainly in the recent 4 years to change the surgical strategy in the region of hip joint. The authors describe their own technique of releasing of iliopsoas muscle in patients with infantile cerebral palsy and present indications of combinations of surgeries on muscles in he region of the hip joint. Surgery on muscles is performed and muscular balance is ensured in infantile cerebral palsy either in order to prevent later migration or even dislocation or in cases where the dislocation has already occurred as the basic or preliminary surgery for a closed or open reduction. In 70 % cases the progress of lateral migration of the hip joint in spastic patients has been improved and thus prevented by a combined surgery. Key words: infantile cerebral palsy, coxa valga antetorta neurogenes, subluxans, luxans, lateral migration of the head, tenotomy of adductors, tenotomy of iliopsoas muscle.

[Our Experience in the Use of BAS-0 Bioactive Glass-ceramic in Orthoses in the Region of the Ankle.]. / Nase zkusenosti s vyuzitím bioaktivní sklokeramiky BAS-0 pri artrodézách v oblasti hlezna.

Extra-articular arthrodesis after Grice is indicated for the treatment of serious pes planovalgus or equinovalgus after the stabilisation of muscular relations in patients with infantile cerebral palsy. The surgical technique itself inspired the authors to use glass-ceramic blocks BAS-0 which were manufactured in co-operation with LASACK. In the period of 1995-1996 they used the glass-ceramic blocks 15times in 14 patients (1 patient operated bilaterally). Thirteen times they used glass-ceramic block in extra-articular arthrodesis, of which in 9 cases in combination with the Young technique, in two cases as part of subtalar arthrodeses. The criterion for the evaluation of the results was the axial alignment between talus and the long axis of the first metatarsus. Excellent and good results were achieved in 9 cases. In these cases the bioactive glass-ceramic block was always encased by bone graft and combined with the surgery after Young. In extraarticular arthrodesis the bones are not in contact. According to authors the glass ceramic block behaves in loading of the neighbouring bone as a "corpus alienum". As a result the ingrowth does not occur. Consequently, the radiograph shows a radioluscent line around the block. Even though the blocks were suitable from the viewpoint of their strength, they did not meet the expectations of authors in this indication. There did not occur a stable incorporation in the surrounding bone. Key words: BAS-0 bioactive glass-ceramics, Grice technique, Young technique, glass ceramic block.

[Personal experience with treatment of congenital pes equinovarus]. / Nase zkusenosti s lécením pes equinovarus congenitus.

The authors evaluated a group of 256 children operated in 1983-1992 at the Orthopaedic Clinic of the Faculty Hospital on account of congenital pes equinovarus. These children account for 25% of the total number of children treated because of this inborn defect by conservative treatment. The authors draw attention to the lack of uniformity of contemporary treatment of congenital pes equinovarus, and based on their own experience, they recommend an exact therapeutic plan. They emphasize the importance of early treatment by means of corrective plaster bandages, they describe the tactics of treatment by this method, as any deviation from this therapeutic pattern leads to incomplete elimination of the defect and to relapses. The authors present also a general review of possible surgical treatment and emphasize the tactics of postoperative treatment, incl. intensive rehabilitation and correction by footwear. They emphasize in particular the necessity of systematic and uninterrupted conservative treatment which is essential as preoperative preparation, as only by intensive care before and after surgery, incl. a correctly indicated and implemented operation, the desired goal, i.e. an anatomical position of the foot can be achieved.

[Orthopedic surgery in children with cerebral palsy]. / Ortopedické operacní lécení detí postizených detskou mozkovou obrnou.

The authors present their experience with orthopaedic surgical treatment of children with cerebral palsy. The paper is based on a group of 630 patients where they performed 1882 operations of the lower extremities in 1970-1992. The authors evaluate the long-term results in regularly checked 361 patients (205 boys and 156 girls), mostly with the spastic form of cerebral palsy, with regard to different types of affections which markedly influence the prognosis of surgery (monoparesis, hemiparesis, diparesis, triparesis, quadruparesis). The authors emphasize the primary importance of rehabilitation and team work where the orthopaedist's work is guided by efforts to make further rehabilitation training possible and to facilitate it. They consider surgery an integral part of comprehensive treatment of cerebral palsy which must be followed immediately by further rehabilitation. The authors emphasize the part played be the orthopaedic surgeon to prevent the genesis and development of deformities of the locomotor apparatus.

On the mechanical function of tendon.

A mesoscopic approach is followed for mathematical modelling of the specific deformation properties of tendon. The approach starts from our general concept of modelling mechanical behaviour of heterogeneous media and assumes that the structure of tendon is optimized in such a way that it enables its adjacent muscle to work with a constant performance in the course of increasing loading (acting like a gearbox in a car). The model based on this assumption gives results that are in a very good accordance with observed properties of tendons. Clinical experience reveals that if this function of tendon is violated pathological changes appear in the respective muscle. RELEVANCE: Clarification and mathematical modelling of the mechanical function of tendon is of intellectual interest in its own right, but it is important also for cautioning surgeons against unnecessary violation of this function, and for tissue engineering aspects if tendon must be replaced.