Von der tibiofemoralen Instabilität zur Luxation in der Knieendoprothetik

Tibiofemoral instability is increasingly recognized as a mode of failure in total knee arthroplasty (TKA). Severe instability may lead to dislocation. Wrong surgical technique and wrong choice of constraint of the prostheses are the main causes for instability. Malalignment, malrotation and intraoperatively uncorrected instability especially in flexion may lead to an unstable total knee arthroplasty. Cruciate-retaining designs and mobile platforms can be considered only in the presence of well-balanced ligaments. Cruciate-substituting designs give more stability and many people find them more forgiving. However, correction of varus-valgus instability and severe flexion laxity cannot be provided. Varus-valgus contrained designs cannot compensate for the absence of medial and lateral collateral ligaments. Such cases are most reliably treated with a linked implant (rotating hinge). The exact analysis of the cause of an unstable or dislocated total knee arthroplasty represents the most essential basis of a successful treatment. Exchange of the prostheses represents the most successful procedure. Correction of implantation failures should be performed. A more constrained design should be used if insufficient ligaments are found. Post-traumatic instability or dislocation represents an exception.

Short-term outcome of painful bone marrow oedema of the knee following oral treatment with iloprost or tramadol: results of an exploratory phase II study of 41 patients

OBJECTIVES

To compare the therapeutic effects of oral iloprost and tramadol on the outcome of bone marrow oedema (BME) of the knee by MR imaging and clinical assessment.

METHODS

Forty-one patients with painful ischemic or mechanical BME of the knee were enrolled in a double-blind, randomized controlled study. Patients were randomized either to iloprost (n = 21, group 1) or tramadol (n = 20, group 2). The treatment duration was 4 weeks. The Larson knee score was used to assess function before treatment and then 3 days, 1, 2, 3, 4 weeks and 3 months after the start of treatment. Short tau inversion recovery and T1-weighted MR images of the affected knees were obtained before and 3 months after the start of treatment. Bone marrow oedema was assessed visually and by computer-assisted quantification for baseline and follow-up MR examinations.

RESULTS

Thirty-three patients completed the study as scheduled. The mean Larson score improved from 58.6 points to 81.8 points in group 1, and from 59.6 points to 86.8 points in group 2, after 3 months (no significant difference between the treatment groups). On MR images, complete BME regression in at least one bone was observed in nine patients (52.9%) in group 1, as opposed to three patients (18.7%) in group 2, after 3 months (P = 0.034). Correspondingly, the median BME volume decreased by 58.0% in group 1, and by 47.5% in group 2.

CONCLUSIONS

The analgesic effect of iloprost and tramadol was similar. BME regression on MR images was more pronounced under iloprost treatment.

Circulating tumor cells (CTCs) in peripheral blood of primary breast cancer patients

10595

Background: Detection of CTCs has been shown to predict decreased PFS and OAS in metastatic breast cancer, whereas only limited data has been published in the adjuvant setting. We evaluate the role of CTCs in peripheral blood at primary diagnosis and during adjuvant chemotherapy, endocrine and bisphophonate treatment within the SUCCESS-Trial (n=3,658 pts). Methods: We analyzed 23ml of peripheral blood from 1767 N+ and high risk N- primary breast cancer pts before systemic treatment. 852 of these pts have undergone follow-up blood sampling after completion of chemotherapy. The presence of CTCs was assessed with the CellSearchSystem (Veridex, Warren, USA). Briefly, after immunomagnetic enrichment with an anti-Epcam-antibody, cells were labelled with anti-cytokeratin (8,18,19) and anti-CD45 antibodies to distinguish epithelial cells and leukocytes. Results: 10% of pts with a blood sampling before systemic treatment (n=170) showed >1CTC before the start of systemic treatment (mean 13, range 2–827). While we found 2 CTCs in 5% of pts, 3% had 3–5 CTCs and 1% 6–10 and >10 CTCs each. The presence of CTCs did not correlate with tumor size (p=.07), grading (p=.30), hormonal status (p=.54) or Her2-Status of the primary tumor (p=.26). However, we observed a significant correlation with the presence of lymph node metastases (p=.015). None of 24 healthy individuals showed more than 1 CTC. Among those 852 pts with follow-up blood sampling after the completion of cytostatic treatment, 11% were CTC positive before starting systemic treatment (mean 7, range 2–166), while 7% of patients presented with >1CTC after completion of chemotherapy (mean 6, range 2–84). Of those, initially CTC positive, 10% remained positive (n=9) and 90% had a negative CTC test after chemotherapy (n=82). Of those initially CTC negative, 93% remained negative (n=711), whereas 7% returned with a positive CTC test (n=50) (p=.24). Conclusions: Our data show good feasibility of this highly standardized and easily applicable approach for the detection of CTCs in a large number of primary breast cancer patients. In a considerable number of patients, persistent CTCs can be detected after completion of cytostatic treatment. Whether this finding is prognostically relevant will have to been shown with longer follow-up of the SUCCESS-trial.

No significant financial relationships to disclose.

BMP-silk composite matrices heal critically sized femoral defects

Clinical drawbacks of bone grafting prompt the search for alternative bone augmentation technologies such as use of growth and differentiation factors, gene therapy, and cell therapy. Osteopromotive matrices are frequently employed for the local delivery and controlled release of these augmentation agents. Some matrices also provide an osteoconductive scaffold to support new bone growth. In this study, silkworm-derived silk fibroin was evaluated as an osteoconductive matrix for healing critical sized mid-femoral segmental defects in nude rats. Four treatment groups were assessed over eight weeks: silk scaffolds (SS) with recombinant human BMP-2 (rhBMP-2) and human mesenchymal stem cells (HMSC) that had been pre-differentiated along an osteoblastic lineage ex vivo (Group I; pdHMSC/rhBMP-2/SS); SS with rhBMP-2 and undifferentiated HMSCs (Group II; udHMSC/rhBMP-2/SS); SS and rhBMP-2 alone (Group III; rhBMP-2/SS); and empty defects (Group IV). Bi-weekly radiographs revealed a progressive and similar increase in Group I-III mean defect mineralization through post-operative week (POW) 8. Radiographs, dual energy x-ray absorptiometry, and micro-computed tomography confirmed that Groups I-III exhibited similar substantial and significantly (p<0.05) greater defect mineralization at POW 8 than the unfilled Group IV defects which remained void of bone. No significant differences in Groups I-III defect healing at POW 8 were apparent using these same assays or mechanical testing. Histology at POW 8 revealed moderately good bridging of the parent diaphyseal cortices with woven and lamellar bone bridging islands of silk matrix in Groups I and III. Group II defects possessed comparatively less new bone which was most abundant adjacent to the parent bone margins. Elsewhere the silk matrix was more often enveloped by poorly differentiated loose fibrous connective tissue. Group IV defects showed minimal new bone formation. None of the treatment groups attained the mean mineralization or the mean biomechanical strength of identical defects implanted with SS and pdHMSCs alone in a previous study. However, addition of rhBMP-2 to SS prompted more bone than was previously generated using udHMSC/SS or SS alone. These data imply the clinical potential of silk scaffolds and rhBMP-2 as composite osteopromotive implants when used alone or with select stem cell populations. Additional studies in larger species are now warranted.

Perioperative antibiotische Prophylaxe

Perioperative antibiotic prophylaxis in orthopaedics is only indicated if a foreign body such as a prosthetic joint remains in the operation site. For this indication first or second generation cephalosporins should be preferred. It is essential to administer the antibiotic within 30 min before incision. In the case of an extended intervention (more than 3 h) a repeated dose should be considered. It is evidence-based that prolonged perioperative antibiotic prophylaxis (more then 24 h) is not beneficial. To avoid the emergence of resistances or hygienic insufficiencies surveillance of surgical site infections should be enforced. Optimal conditions are necessary to achieve a rate of surgical site infection in orthopaedics below 1% in patients with normal infection risk profile.

Incidence of circulating tumor cells (CTCs) in peripheral blood of breast cancer patients at primary diagnosis—A potential tool for risk stratification

20053

Background: In metastatic breast cancer, CTCs have been proven an independent predictor for progression-free and overall survival (Cristofanilli, NEJM 2004). Therefore, we evaluated the role of CTCs in peripheral blood of breast cancer patients at primary diagnosis and during adjuvant systemic treatment within the Success-Trial (n = 3,658 pts). First results of the incidence of CTCs prior to chemotherapy will be presented here. Methods: The CellSearchSystem (Veridex) was used for isolation and enumeration of CTCs from 23 ml of peripheral blood. Briefly, after immunomagnetic enrichment with an anti-Epcam-antibody, cells were labelled with anti-cytokeratin (8,18,19) and anti-CD45 antibodies to distinguish epithelial cells and leukocytes. Patients had been accrued between September and December 2005. Results: We analyzed 124 breast cancer patients at the time of primary diagnosis. The majority of patients presented with small tumors (41% T1, 55% T2, 4% T3), and 32% were node-negative (45% N1, 14% N2, 9% N3). While a positive hormone receptor status was observed in 74% of patients and 31% were her2/neu positive, most tumors showed an intermediate or unfavourable grading (2% G1, 98% G2–3). In this patient group, 32% of patients (n = 40) presented with ≥1CTC in peripheral blood. In patients with the detection of CTCs, the mean number of cells was 5 (range 1–38). In 11 healthy individuals we found 1 CTC in one blood sample. The presence of CTCs did not correlated with tumor size (p = .39), presence of lymph node metastases (p = .25), histopathological grading (p = .33), hormone receptor status (p = .56) or her2/neu status of the primary tumor (p = .14). Conclusions: The isolation of CTCs from peripheral blood of primary breast cancer patients is feasible and might prove as an easy applicable and convenient technique to give further insight into the spread of the disease. The Success-Trial will investigate, whether CTCs can be used for risk stratification to more tailored treatment approaches and for the monitoring of treatment efficacy in individual patients.

[Table: see text]

[Value of radiographic examination of the knee joint for the orthopedic surgeon]

Extended radiographic examinations offer excellent options for diagnosis and strategy for treatment of the knee joint. The whole-leg radiograph is indispensable in measuring alignment for osteotomy or total knee arthroplasty (TKA). Fluoroscopically assisted varus-valgus stress radiographs provide the possibility for verifying mechanical function of the implanted knee prosthesis. Ultrasound examinations have been widely replaced by magnetic resonance imaging (MRI). MRI is the golden standard to examine intra-articular structures of the knee (meniscus, ligaments, cartilage) and surrounding soft tissue. For evaluating femoral and tibial torsion and determining axial rotation of TKA, computed tomography (CT) is best qualified. Imaging of the patellofemoral joint (patella instability) is difficult; CT scans in combination with true lateral radiographs seem to be helpful.

Knochenmarködem im Kniegelenk

The Bone marrow edema (BME) is a common finding when evaluating patients with knee pain by magnetic resonance imaging (MRI). The typical signal patterns of BME are unspecific and can be found with different diseases of the knee. Since different therapeutic approaches are mandatory, differential diagnosis of the several forms of BME is important. In this review, painful BME will be separated into three different etiological groups. Group 1 ischemic BME: osteonecrosis, osteochondritis dissecans, bone marrow edema syndrome and complex regional pain syndrome. Group 2 mechanical BME: bone bruises, microfracture, stress-BME und stress fracture. Group 3 reactive BME: inflammatory gonarthritis, degenerative gonarthrosis, postoperative and tumours. The typical MRI morphologies and differential diagnosis of these BME manifestations will be described. The different therapeutic consequences will also be briefly mentioned.

Deterministic shape-selective synthesis of nanowires, nanoribbons and nanosaws by steady-state vapour-transport

We demonstrate the deterministic shape-selective synthesis and growth of CdSe nanowires, nanosaws and nanoribbons by a simple vapour-transport process in a tube furnace. The key step, in order to achieve reproducible shape selectivity for a given set of deposition parameters, is to exclude any effects of the temperature ramping. We prove that an efficient precursor-flow shutter is achieved just by varying the total furnace pressure. We then present a shape-diagram linking the different nanocrystals morphologies to only two parameters: powder and substrate temperature. These are varied in the 550-700 °C and 400-600 °C range, respectively. A model explaining the shape control is discussed.

Silk fibroin as an organic polymer for controlled drug delivery

The pharmaceutical utility of silk fibroin (SF) materials for drug delivery was investigated. SF films were prepared from aqueous solutions of the fibroin protein polymer and crystallinity was induced and controlled by methanol treatment. Dextrans of different molecular weights, as well as proteins, were physically entrapped into the drug delivery device during processing into films. Drug release kinetics were evaluated as a function of dextran molecular weight, and film crystallinity. Treatment with methanol resulted in an increase in beta-sheet structure, an increase in crystallinity and an increase in film surface hydrophobicity determined by FTIR, X-ray and contact angle techniques, respectively. The increase in crystallinity resulted in the sustained release of dextrans of molecular weights ranging from 4 to 40 kDa, whereas for less crystalline films sustained release was confined to the 40 kDa dextran. Protein release from the films was studied with horseradish peroxidase (HRP) and lysozyme (Lys) as model compounds. Enzyme release from the less crystalline films resulted in a biphasic release pattern, characterized by an initial release within the first 36 h, followed by a lag phase and continuous release between days 3 and 11. No initial burst was observed for films with higher crystallinity and subsequent release patterns followed linear kinetics for HRP, or no substantial release for Lys. In conclusion, SF is an interesting polymer for drug delivery of polysaccharides and bioactive proteins due to the controllable level of crystallinity and the ability to process the biomaterial in biocompatible fashion under ambient conditions to avoid damage to labile compounds to be delivered.

Differenzialdiagnosen des Knochenmarködems am Kniegelenk

Bone marrow edema of the knee joint is a frequent clinical picture in MR diagnostics. It can be accompanied by symptoms and pain in the joint. Diseases that are associated with bone marrow edema can be classified into different groups. Group 1 includes vascular ischemic bone marrow edema with osteonecrosis (synonyms: SONK or Ahlbäck's disease), osteochondrosis dissecans, and bone marrow edema syndrome. Group 2 comprises traumatic or mechanical bone marrow edema. Group 3 encompasses reactive bone marrow edemas such as those occurring in gonarthrosis, postoperative bone marrow edemas, and reactive edemas in tumors or tumor-like diseases. Evidence for bone marrow edema is effectively provided by MRI, but purely morphological MR information is often unspecific so that anamnestic and clinical details are necessary in most cases for definitive disease classification.

Surface diffusion: the low activation energy path for nanotube growth

We present the temperature dependence of the growth rate of carbon nanofibers by plasma-enhanced chemical vapor deposition with Ni, Co, and Fe catalysts. We extrapolate a common low activation energy of 0.23-0.4 eV, much lower than for thermal deposition. The carbon diffusion on the catalyst surface and the stability of the precursor molecules, C2H2 or CH4, are investigated by ab initio plane wave density functional calculations. We find a low activation energy of 0.4 eV for carbon surface diffusion on Ni and Co (111) planes, much lower than for bulk diffusion. The energy barrier for C2H2 and CH4 dissociation is at least 1.3 eV and 0.9 eV, respectively, on Ni(111) planes or step edges. Hence, the rate-limiting step for plasma-enhanced growth is carbon diffusion on the catalyst surface, while an extra barrier is present for thermal growth due to gas decomposition.

Die Osteonekrose des Hüftgelenkes im Erwachsenenalter

Osteonecrosis of the hip (ON) in the adult is still an unsolved therapeutic problem. New pathophysiological findings have increased our knowledge of the disease course. Technical progress in imaging modalities and a better understanding of pathomorphology have improved the diagnostic procedure. The most significant progress for pathophysiology, early diagnosis and therapeutic decision making has been evolved by the routine use of MR-imaging. Using the international ARCO staging system, the pathomorphological and imaging changes during the different ON stages are described in this review. A diagnostic algorithm for ON is proposed. There are numerous conservative and surgical therapeutic approaches to ON, and the number of these is still increasing. A short overview of the most common therapeutic concepts is given. Finally, recommendations for therapeutic decision making for daily practice are proposed.

Age associated changes of AGE-receptor expression: RAGE upregulation is associated with human heart dysfunction

The binding of advanced glycation endproducts (AGEs) to their receptors is known to cause changes in cell function during normal ageing and is implicated in the pathogenesis of cardiovascular disease. In this study, expression of the AGE-receptor 3 (AGE-R3) and the receptor for AGEs (RAGE) was compared on the mRNA and protein level in the ageing human heart. Western blot and RT-PCR analysis of the AGE receptors from the cardiac auricles in senescent and adult patients was performed and compared with young controls. Whereas the expressions of AGE-R3 as well as RAGE protein were significantly upregulated in the senescent population, only the upregulation of RAGE is associated with reduced heart function. Therefore, our results support a pathophysiological function for RAGE in the ageing human heart.

Sputter-depth profiling for thin-film analysis

Following a brief historical background, the concepts and the present state of sputter-depth profiling for thin-film analysis are outlined. There are two main branches: either the removed matter (as in mass- or optical-spectroscopy-based secondary-ion mass spectrometry or glow-discharge optical emission spectroscopy), or the remaining surface (as in Auger electron spectroscopy and X-ray photoelectron spectroscopy) is characterized. These complementary methods show the same result if there is no preferential sputtering of a component. The common root of both is the fundamental ion-solid interaction. Understanding of how the latter influences the depth resolution has led to important improvements in experimental profiling conditions such as sample rotation and the use of low-energy ions at glancing incidence. Modern surface-analysis instruments can provide high-resolution depth profiles on the nanometre scale. Mathematical models of different sophistication were developed to allow deconvolution of the measured profile or quantification by reconstruction of the in-depth distribution of composition. For the latter purpose, the usefulness of the so-called mixing-roughness-information (MRI) depth model is outlined on several thin-film structures (e.g. AlAs/GaAs and Si/Ge), including its extension to quantification of sputter-depth profiles in layer structures with preferential sputtering of one component (Ta/Si). Using the MRI model, diffusion coefficients at interfaces as low as 10(-22) m(2) s(-1) can be determined. Fundamental limitations of sputter-depth profiling are mainly traced back to the stochastic nature of primary-particle energy transfer to the sputtered particle, promoting atomic mixing and the development of surface roughness. Owing to more sophisticated experimental methods, such as low-energy cluster ion bombardment, glancing ion incidence or 'backside' sputtering, these ultimate limitations can be reduced to the atomic monolayer scale.

Growth of aligned carbon nanofibres over large areas using colloidal catalysts at low temperatures

Highly purified cobalt colloids have been employed as a catalyst to grow aligned carbon nanofibres at temperatures as low as 300 degree C by dc plasma enhanced chemical vapour deposition over large areas.

Painful nonunion after triple pelvic osteotomy. Report of five cases

Tönnis triple pelvic osteotomy is an accepted technique to correct acetabular dysplasia and degenerative labral pathology. A series of 409 consecutive patients who underwent a triple pelvic osteotomy between 1987 and 1999 were followed for a mean of 7.1 years (2 to 15). Five patients (1.2%), all women, developed a double nonunion and required revision, which involved excision of the pseudarthrosis, autologous bone grafting and osteosynthesis with screws or reconstruction plates. Bony healing was achieved in all after a mean of 7.8 months.

[Significance of axial rotation alignment of components of knee prostheses]

Increased internal malrotation of the tibial and femoral components affects kinematics of the patellofemoral joint and the flexion gap. A combined tibial and femoral malrotation may lead to maltracking of the patella. Isolated internal malrotation of the femoral component results in an asymmetric flexion gap. Clinically, the patients suffer from either lateral instability or medial stiffness in flexion. Lateral flexion instability leads to medial tibial pain,difficulties standing up from a chair,or instability during descending stairs or walking downhill. Medial stiffness in flexion may lead to secondary arthrofibrosis. There are three methods for determining femoral rotation by bony landmarks: (1) posterior condyles with 3 degrees of external rotation, (2) anterior-posterior axis according to Whiteside, and (3) transepicondylar axis. The transepicondylar axis approximates the flexion axis of the knee. All three bony landmarks have the disadvantage that they will not create a symmetric flexion gap in all cases. The balanced flexion gap technique seeks to achieve a perfectly balanced extension gap first, and then aligns the femoral component parallel to the tibial resection plane when the knee is under symmetric distraction in 90 degrees of flexion. The soft tissue releases for varus or valgus contraction have to be performed in extension first until the mechanical axis passes through the center of the knee, the center of the femoral head, and the center of the ankle. Using these methods, both,extension and flexion gap will become rectangular. The balanced flexion gap method has the disadvantage that the femoral component will not be aligned parallel to the epicondylar axis in some cases. It is not known which of the two methods will produce better clinical results. Rotational positioning of the tibial component referenced on the tibial tuberosity represents the most reliable method. Placing the tibial component according to the femoral component using the floating technique may increase an internal malrotation problem of the femur if present.

[Temporary articulating spacer with antibiotic-impregnated cement for an infected knee endoprosthesis]

Two-stage reimplantation remains the gold standard in the treatment of late infected total knee arthroplasties. The reported disadvantages include difficult exposure at the time of reimplantation and less functional outcome by using static spacers. Patients who receive an articulating spacer retain a functional joint before second-stage reimplantation. This may reduce the disadvantages of static spacers (ligament contracture, extensor lag, arthrofibrosis). There is no difference in the success rates of eradicating infection (range: 90-96%). In a prospective study 24 consecutive patients were treated with an articulating spacer. The articulating spacer is made by cleaning and autoclaving the removed femoral component and the tibial polyethylene insert. These are reinserted during the same operation with antibiotic-loaded cement. The average time during which the spacer was in place was 16 weeks (range: 7-28 weeks). During an average follow-up period of 14.8 months (range: 5-33 months) one patient had a secondary reinfection. Use of an articulating spacer is economical and decreases the risk of complications in reimplantation with good functional outcome.

[Rotational malalignment of the components may cause chronic pain or early failure in total knee arthroplasty]

Rotational alignment of the tibial and femoral component plays an important role in modern total knee replacement surgery. After correct frontal alignment and proper soft tissue balancing, the rotational placement of the components represents the "third dimension" in knee endoprosthetic surgery. Improved surgical techniques with modified instruments and better rotational component positioning will lead to better functional outcomes. Patients with painful total knee arthroplasties (TKA) or early failure without evident classic implantation failures or signs of infection should be evaluated for malrotation of the components. In a prospective study in 26 patients with painful TKA and malrotation of the tibia and/or femur component, revision surgery with exchange of the components was performed. Twenty-five cases showed clinically relevant internal malrotation of the tibial component (ø 8.4 degrees ) and/or femoral component (ø 5.6 degrees ). Only one patient had 10 degrees of external malrotation of the femoral component. Combined malrotations of the tibia and femur were found in ten knees (38%). After revision surgery and correction of malrotations, 20 patients (78%) were scored with excellent and good results. Patients with painful TKA resistant to conservative therapy and evident malrotations of the component should be considered for revision surgery with change of the malrotated components.

Mechanical causes of osteoarthritis in young adults

Femoroacetabular impingement is a very common cause of secondary osteoarthritis (OA) in the young adult. It is an important co-factor in the better recognized prearthritic deformities such as residual hip dysplasia (RHD), Perthes disease and slipped capital femoral epiphysis (SCFE). Another subgroup of patients has isolated malrotation of the hip joint and/or reduced femoral head-neck offset causing femoroacetabular impingement and chronic hip joint pain. Special clinical tests and imaging modalities can identify these patients at an early stage when they have little or no OA. The common biomechanical pathway for deformities causing chronic femoroacetabular impingement is local damage of the capsular-labrum complex and the cartilage. Understanding the anatomy, biomechanics and pathophysiology of these conditions of the hip joint is a prerequisite for planning treatment. 

[Rotational abnormalities of the hip joint]

Changes or limitations of the rotational range of motion of the hip are a non-specific clinical sign. There is a big variety of underlying morphological pathologies resulting in a symptomatic alteration of hip rotation. They need to be assessed by imaging techniques: based on plain radiographs (including specialized projections), often CT or MRI are necessary to visualize the underlying changes of shape, rotation and offset of the articulating surfaces, which might result in a painful "femoroacetabular impingement" as a trigger of secondary osteoarthritis. Highly sophisticated MR-arthrography-protocols are able to visualize conventionally "obscure" but biomechanically relevant morphological changes, that might be individually normalized by joint-preserving corrective surgery.

[Perthes disease]

The Legg-Calve-Perthes disease is an idiopathic avascular necrosis of the hip during early childhood. It is characterized by different stages with the main risk of persisting hip deformation, dysfunction of the joint movement, and the potential for early osteoarthritis. For the evaluation of prognosis and therapy planning patients age and extent of the necrotic area of the epiphysis are important factors. For an early diagnosis and sufficient therapy all radiological efforts have to be performed. MR imaging is an ideal method for the assessment of osteonecrotic changes of the Morbus Perthes. Compared to plain radiography by MR imaging pathologic alterations can be detected earlier and with higher specificity. However, conventional radiograms have to be still used as basic imaging modality. Nowadays x-rays and MR imaging should be the main methods for the evaluation of children suffering from Perthes disease.

[Osteonecrosis of the hip joint in adulthood]

Osteonecrosis (ON) of the hip joint remains an unsolved therapeutical problem. Diagnosis of ON of the hip has been improved by the technical progress of imaging modalities and better understanding pathomorphology. Over a long period only plain radiographs have been available. Scintigraphy and computed tomography contributed to differential diagnosis and early detection of bone necrosis. Diagnosis in an early reversible stage is of importance. Understanding of pathophysiology, early diagnosis and therapeutical approach has been significantly improved by MR imaging. Using the ARCO system all imaging modalities and their diagnostic viability are described in the five ARCO stages. At the end a diagnostic algorithm will be proposed.

[MR arthrography of the hip joint]

MR arthrography of the hip joint is usually performed after a conventional MRI has been obtained to rule out other pathologies of the hip joint as for instance bone marrow edema or osteonecrosis of the hip. MR arthrography is mainly performed as a very special investigation, and it is executed in most cases if the clinician asks for the diagnosis of a labral lesion. In very rare cases, MR arthrography of the hip is performed to image cartilage disease or osteochondrosis dissecans or free intraarticular bodies. In this paper, the indications, the technique, and the most important pathology of the hip joint--labral lesions--will be described as well as variants of the normal acetabular labrum. After a conventional MRI of the hip joint has been performed, a MR arthrography of the hip will be obtained to search for labral pathology or cartilage disease. MR arthrography is obtained after the intraarticular injection of 10-20 ml of a 0.1 mmol solution of gadopentate-dimeglumine has been performed. The intraarticular injection can either be fluoroscopic-guided or CT-guided or directly MR-guided. After the intraarticular injection, MR arthrography will be performed by the use of paracoronal and parasagittal T1-weighted spin echo or gradient echo sequences. In cases of labral lesions (degeneration, labral tear, labral detachment) or cartilage disease MR arthrography proved to be more sensitive as conventional MRI as shown in the literature. The sensitivity of MRI to detect labral pathology was reported to be about 65%, and that of MR arthrography was reported to be about 92-95% compared to surgical results. According to the current literature, MR arthrography is the most sensitive method to delineate these kind of pathologies. Therefore, the invasive technique of MR arthrography may be justified for the correct diagnosis of these kind of pathologies after other pathologic entities have been ruled out by conventional MRI.

The tumour necrosis factor-alpha induced vascular permeability is associated with a reduction of VE-cadherin expression

BACKGROUND

Vascular permeability is controlled by endothelial cell-to-cell junctions. Vascular endothelial (VE)-cadherin, the major component of adherence junctions (AJ) in the endothelium, is the target of the permeability-increasing agent tumour necrosis factor-a (TNF-alpha). We investigated whether TNF-alpha regulates the synthesis of VE-cadherin on the transcriptional level.

MATERIALS AND METHODS

Human endothelial cells, isolated from aorta (aEC) and umbilical cord (HUVEC), were exposed to TNF-alpha (200 U/ml) for 6 h or 12 h, with and without subsequent incubation with TNF-alpha for 24 h. VE-cadherin mRNA was evaluated by semi-quantitative RT-PCR. The VE-Cadherin protein expression was analyzed by flow cytometry (FACS).

RESULTS

The VE-cadherin amplification curve of TNF-alpha treated cells was shifted to the right compared to controls, indicating a lower mRNA amount. The number of cycles at which half-maximal amplification (N50) was achieved, was lower for control aEC (30.7) than for TNF-alpha treated aEC (33.0). The N50 of HUVEC treated with TNF-alpha for 12 h and 12 h + 24 h medium (N50 = 32.1), was higher compared to controls (N50 = 29.7) and cells treated with TNF-alpha for 6 h (N50 = 30.8). As determined by FACS analysis, incubation with TNF-alpha caused a small decrease of VE-cadherin protein expression from 7.44 to 6.05 mean channel intensity.

CONCLUSION

Our results indicate that TNF-alpha affects VE-cadherin gene expression on the transcriptional level, inducing a downregulation of the VE-cadherin expression.

Screening for carnitine palmitoyltransferase II deficiency by tandem mass spectrometry

Mitochondrial carnitine palmitoyltransferase II (CPT II) deficiency is the most common inherited disorder of lipid metabolism in adults. Currently the routine diagnosis is based on the determination of CPT enzyme activity in muscle tissue. We have analysed the tandem mass spectra of serum acylcarnitines of nine CPT II-deficient patients. These spectra were compared to those of a cohort of 99 patients with other neuromuscular disorders and metabolic conditions supposed to cause alterations of the long-chain acylcarnitines. The spectra in CPT II deficiency showed characteristic elevations of C16:0 and C18:1 acylcarnitines while acetylcarnitine C2 was not elevated. In the present study, the ratio (C16:0+C18:1)/C2 has detected all CPT II deficiencies and discriminated them from unspecific alterations of serum acylcarnitines. The ratios of CPT II-deficient patients showed virtually no overlap with those observed in patients with other neuromuscular disorders. We suggest mass spectrometry of serum acylcarnitines as a rapid screening test that should be included early in the diagnostic work-up of patients with recurrent myoglobinuria, recurrent muscular weakness and myalgia.