Under-correction of preoperative varus alignment does not lead to a difference in in-vivo bone loading in 3D-SPECT/CT compared to neutral alignment.

BACKGROUND: The aim was to investigate the correlation of bone tracer uptake (BTU) in SPECT/CT and changes in coronal knee alignment after total knee arthroplasty (TKA). We questioned if undercorrection of preoperative varus alignment leads to a difference in BTU compared to neutral alignment. METHODS: Consecutive 66 patients who received SPECT/CT before and after TKA were retrospectively included. Adjusted mechanical alignment was the alignment target. The alignment of the knee was measured on 3D-CT by selecting standardized landmarks. Maximum (mean ± SD) and relative BTU (ratio to the reference) were recorded using a previously validated localization scheme (p < 0.05). RESULTS: In the native group, 20 knees were aligned (30.3%) in valgus (HKA > 181.5°), 12 (18.2%) in neutral (178.5°-181.5°) and 34 (51.5%) in varus (HKA < 178°). Overall TKA changed the alignment towards neutral. 48.5% remained in the same groups, whereas 50% of native valgus and 33% of varus knees changed to neutral after TKA. In native varus alignment mean BTU was significantly higher in some medial tibial and femoral regions (fem1ia (p = 0.010), fem1ip (p = 0.002), tib1a.mid (p = 0.005), tib1a.tray (p = 0.000), tib1p.tray (p = 0.000)); in native valgus alignment mean BTU was higher in the corresponding lateral tibial and femoral regions (fem2ip (p = 0.001), tib2a.tray (p = 0.011), tib2p.tray (p = 0.002)). After TKA, a significant decrease in femoral and tibial BTU (femoral preoperative BTU 1.64 +/-0.69; femoral postoperative BTU 0.95 +/-0.42; p = 0.000// tibial preoperative BTU 1.65 +/- 0.93; tibial postoperative BTU 1.16 +/- 0.48; p = 0.000) and an increase in patellar BTU was observed (p = 0.025). Native varus alignment correlated with a higher medial BTU decrease medially. Undercorrection of preoperative varus alignment showed no higher BTU after TKA. CONCLUSION: Preoperative varus alignment correlated with a higher decrease in BTU in specific femoral and tibial medial regions. Preoperative valgus alignment correlated with a higher decrease in the corresponding lateral regions. Undercorrection of preoperative varus alignment did not lead to higher bone loading reflected by BTU after TKA.

Increased patellar bone tracer uptake in preoperative SPECT/CT before medial opening high tibial osteotomy correlates with inferior clinical outcome.

PURPOSE: The purpose of this study was to investigate whether specific bone tracer uptake (BTU) patterns on preoperative SPECT/CT could predict which patients with varus alignment and medial overload would particularly benefit from medial opening-wedge high tibial osteotomy (MOWHTO). It was the hypothesis that an increased preoperative BTU relative to the reference BTU of the femur on SPECT/CT in the lateral and patellar compartments of the knee are predictive factors for inferior clinical outcome and that the clinical outcome correlates with the extent of alignment correction. METHODS: Twenty-three knees from 22 patients who underwent MOWHTO for medial compartment overload were investigated preoperatively using Tc-99m-SPECT/CT. BTU was quantified and localised to specific joint areas according to a previously validated scheme. Pre- and postoperative mechanical alignment was measured. Clinical outcome was assessed at a median of 24 months (range 11-30) after MOWHTO by collecting the WOMAC score. RESULTS: Significant correlations between BTU in the patellar area and the total WOMAC score and its subcategories pain and stiffness were found. Thus, BTU in the 1sPat area (superior lateral patellar compartment) correlated with total WOMAC (rho = 0.43, p = 0.04), pain subcategory (rho = 0.43, p = 0.04), and stiffness subcategory (rho = 0.59, p = 0.003). No significant correlations were found between alignment correction, age, gender and WOMAC. CONCLUSION: This study highlights the role of preoperative SPECT in modern knee surgery to obtain information about the loading pattern on different compartments of the knee. Despite the limited number of participants, the present study shows that a preoperative SPECT/CT scan can help the treating surgeons to identify patients who may be at risk of inferior clinical outcome if an MOWHTO is considered, as an elevated BTU in the patellar region on preoperative SPECT/CT appears to be a potential risk factor for postoperative pain and stiffness. LEVEL OF EVIDENCE: Level III.

Artificial kagome spin ice: dimensional reduction, avalanche control and emergent magnetic monopoles.

Artificial spin-ice systems consisting of nanolithographic arrays of isolated nanomagnets are model systems for the study of frustration-induced phenomena. We have recently demonstrated that monopoles and Dirac strings can be directly observed via synchrotron-based photoemission electron microscopy, where the magnetic state of individual nanoislands can be imaged in real space. These experimental results of Dirac string formation are in excellent agreement with Monte Carlo simulations of the hysteresis of an array of dipoles situated on a kagome lattice with randomized switching fields. This formation of one-dimensional avalanches in a two-dimensional system is in sharp contrast to disordered thin films, where avalanches associated with magnetization reversal are two-dimensional. The self-organized restriction of avalanches to one dimension provides an example of dimensional reduction due to frustration. We give simple explanations for the origin of this dimensional reduction and discuss the disorder dependence of these avalanches. We conclude with the explicit demonstration of how these avalanches can be controlled via locally modified anisotropies. Such a controlled start and stop of avalanches will have potential applications in data storage and information processing.

Popliteal entrapment syndrome and age.

On the occasion of diagnosing a popliteal entrapment syndrome in a 59-year old man with no cardiovascular risk factors, who developed acute ischemic leg pain during long distance running, we give an overview on this entity with emphasis on patients' age. The different types of the popliteal artery compression syndrome are summarized. The diagnostic and therapeutic approaches are discussed. The most important clinical sign of a popliteal entrapment syndrome is the lack of atherosclerotic risk factors in patients with limited walking distance. Not only in young athletes but also in patients more than 50 years old the popliteal entrapment syndrome has to be taken into account.

Gadofosveset enhanced MR phlebography for detecting pelvic and deep vein leg thrombosis.

BACKGROUND: Deep venous thrombosis is mainly diagnosed by ultrasound today. In some instances diagnosis is challenging and magnetic resonance angiography could be an attractive alternative. Gadofosveset is a blood pool contrast agent with some favourable properties for this purpose. PATIENTS AND METHODS: We investigated eight patients with proven deep venous thrombosis by Gadofosveset enhanced MR phlebography. We performed a 3D gradient-echo sequence with an overall measurement time of 9 minutes and 6 seconds. One minute after injection of Gadofosveset in a concentration of 0.12 ml/kg body weight images were acquired. Thrombi were visualised by their lack of luminal contrast filling. RESULTS: Thrombi were visualised in all patients. In one patient with extended thrombosis a previously undiagnosed ovarian adenocarcinoma was detected additionally. CONCLUSIONS: Deep venous thromboses in lower extremities can be visualised reliably by performing MR phlebography with blood pool contrast agent Gadofosveset. Visualisation of the complete venous system is feasible. This investigation method may be performed in patients difficult to investigate with ultrasound or may be used for planning interventional procedures.

Unusual vascular focal high-grade arterial stenoses in a young woman with systemic lupus erythematosus and secondary antiphospholipid syndrome.

We report the case of a 28-year old woman with an unusual presentation of peripheral arterial occlusive disease clinically characterized by intermittent claudication and bilateral, focal stenoses of the iliac arteries without signs of atherosclerosis in other vascular beds. The successful percutaneous intervention is described in detail and pathogenetic aspects of the disease are discussed.

Impact of a multifunctional image-guided therapy suite on emergency multiple trauma care.

BACKGROUND: The multifunctional image-guided therapy suite (MIGTS), a combined diagnostic and operating theatre, is currently the subject of considerable interest. This study investigated the effect of instituting a MIGTS on the emergency treatment of multiply injured patients. METHODS: This prospective controlled intervention study (MIGTS versus conventional treatment) included consecutive multiply injured trauma patients (Injury Severity Score of 16 or more) admitted between February 2003 and April 2005 to a university hospital. Main outcome measures were time to computed tomography (CT) and number of in-hospital transfers. RESULTS: A total of 168 patients were enrolled, 87 in the MIGTS and 81 in the control group. On average, CT was started at least 13 min sooner in the MIGTS group (P < 0.001), and these patients underwent fewer within-hospital transfers before arrival in the intensive care unit (median 2 versus 4 for controls; odds ratio -2.92, P < 0.001). Team members indicated increased satisfaction with the quality of the MIGTS procedure over the course of the study (P = 0.009). Thirty-day mortality rate (17 per cent for MIGTS versus 22 per cent for controls; P = 0.420) and long-term outcome did not differ between the two groups. CONCLUSION: Implementation of a MIGTS in the emergency treatment of multiple trauma significantly accelerated the procedure and reduced the number of in-hospital transports. REGISTRATION NUMBER: NCT0072213 (http://www.clinicaltrials.gov).

Low-dose intra-arterial contrast-enhanced MR aortography in patients based on a theoretically derived injection protocol.

Multiple intra-arterial contrast agent injections are necessary during MR-guided endovascular interventions. In respect to the approved limits of maximum daily gadolinium dose, a low-dose injection protocol is mandatory. The objective of this study was to derive and apply a low-dose injection protocol for intra-arterial 3D contrast-enhanced MR aortography in patients. Injection rate (Qinj), concentration of injected gadolinium [Gd]inj and aortal blood flow rate (Qblood) were included for the theoretical evaluation of signal intensity (SI) of the arterial lumen. SI simulations were carried out at Qinj=2 versus 4 ml/s in the [Gd]inj range between 0-500 mM. Qinj and [Gd]inj with SI above the 75% threshold of the maximal SI were regarded as optimal injection parameters. [Gd]inj=50 mM and Qinj=4 ml/s were considered as optimal and were administered in five patients for 3D MR aortography. All images revealed clear delineation of the abdominal aorta and its major branches. Mean+/-SD of contrast-to-noise ratios of the abdominal aorta, common iliac and renal artery were 70.2+/-15.2, 58.6+/-12.3 and 67.4+/-12.3. Approximately seven intra-aortal injections would be permissible in patients during MR-guided interventions without exceeding the maximal dose of gadolinium.

[The value of intramedullary boring and intramedullary splinting in revision of infected pseudarthroses]. / Der Wert der Markhöhlenaufbohrung und Markraumschienung bei der Sanierung von Infektpseudarthrosen.

In the treatment of pseudarthrosis with only a segmental loss of bone elements a reconstruction by the Ilizarov method is too complicated, and simple decortication and plastic surgery with cancellous bone grafting is usually too slow. With reference to three cases, it is shown that simultaneous debridement and bone reaming can improve clearance of the infection. Using decortication and autologous cancellous bone grafting, it is possible to leave the center of the bone free by temporarily inserting a silicon tube. As a result cancellous bone can be saved and the danger of a relapse will be minor. In two cases this technique with the central silicon tube was applied for the first time within the scope of plastic surgery with cancellous bone. If, as in the third case, there is enough bone substance in the region of the pseudarthrosis with swelling of the soft tissue or fistulation, in selected cases reaming of the bone cavity and decortication are all that is necessary. The average length of follow up was 19 months. Only in one of our cases did local inflammation recur 9 months after clearance, which healed rapidly with conservative procedures. The other patients had no episodes of this nature. In our group, the patients achieved full weight-bearing on their leg without external support in an average of 5 months. Compared with another study conducted in Liestal, in which a similar group (infected pseudarthrosis with bone defects of 4-11 cm) was treated by the Ilizarov technique, shortening of the treatment by an average of 4 months was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

[Assessment of the nephrotoxicity of amikacin in patients with cystic fibrosis]. / Untersuchung der Nephrotoxizität von Amikacin bei Patienten mit zystischer Fibrose.

Cystic fibrosis patients are at risk for nephrotoxic effects of aminoglycosides. Fifteen cystic fibrosis patients were admitted to hospital with 18 acute exacerbations of pulmonary symptoms associated with the isolation of Pseudomonas aeruginosa from sputum. They were treated intravenously with amikacin and ceftazidime for 14 days. Urinary excretion of N-acetyl-beta-D-glucosaminidase and alpha 1-microglobulin, two markers of tubular damage, and of albumin, a marker of glomerular permeability, was studied before and during treatment. Urinary activity of N-acetyl-beta-D-glucosaminidase and excretion of alpha 1-microglobulin was normal before amikacin treatment in approximately two thirds of patients and pathologically increased at the end of the study in 95%. Urinary albumin excretion was always normal before amikacin treatment and failed to increase consistently during treatment. The pattern of urinary protein excretion observed in the study before and during treatment with amikacin indicates a selective tubular toxicity.

[The AS/BS occlusal angle, a replacement for the ANB angle]. / Der ASBS/Okklusalwinkel, ein Ersatz für den Winkel ANB.

In cephalometrics the ASBS/Occlusal angle and the "Wits" appraisal determine the sagittal discrepancy between the upper and lower jaw precisely. Standardizing procedures in locating points A, B and Mo are primarily introduced in order to reflect the anatomical situation without any distortion. The accuracy in reproducing the said cephalometric points, lines, angles and distances is proved and the behaviour of the ASBS/Occlusal angle, the "Wits" appraisal and the angle ANB is shown in ideal cases and in class II/1, II/2 And III malocclusions. It is recommended to use either the ASBS/Occlusal angle or the "Wits" appraisal as a cephalometric measurement of sagittal jaw relationship and to locate points AS, BS and Mo according to the standardizing procedures described.