Formation of organorhodium complexes via C–H bond activation of 1,3-di(phenylazo)benzene

Reaction of a potential NCN-pincer ligand, viz. 1,3-di(phenylazo)benzene (L), with [Rh(PPh3)(3)Cl] affords, via a C-H bond activation, an interesting dinuclear Rh(II) complex (1), and with RhCl3 center dot 3H(2)O affords a mononuclear Rh(III) complex (2) containing a catalytically useful Rh-OH2 fragment.

Synthesis, characterization and catalytic performances of ruthenium-based catalysts for the acceptorless dehydrogenative coupling of butanol

A growing interest towards new sources of energy has led in recent years to the development of a new generation of catalysts for alcohol dehydrogenative coupling (ADC). This green, atom-efficient reaction is capable of turning alcohol derivatives into higher value and chemically more attractive ester molecules, and it finds interesting applications in the transformation of the large variety of products deriving from biomass. In the present work, a new series of ruthenium-PNP pincer complexes are investigated for the transformation of 1-butanol, one of the most challenging substrates for this type of reactions, into butyl butyrate, a short-chain symmetrical ester widely used in flavor industries. Since the reaction kinetics depends on hydrogen diffusion, the study aimed at identifying proper reactor type and right catalyst concentration to avoid mass transfer interferences and to get dependable data. A comparison between catalytic activities and productivities has been made to establish the role of the different ligands bonded both to the PNP binder and to the ruthenium metal center, and hence to find the best catalyst for this type of reaction.

Histology of damaged acetabular cartilage in symptomatic femoroacetabular impingement: an observational analysis

This prospective study on symptomatic adult patients with femoroacetabular impingement (FAI) who underwent open surgical intervention for management was designed to identify any obvious histological differences in the damaged acetabular cartilage within different subgroups of FAI. 20 patients underwent surgical intervention following safe surgical dislocation of the hip. There were 6 cases of cam impingement, 5 cases of pincer impingement and 9 of the mixed type. Pincer impingement cases demonstrated a characteristic focal, well-circumscribed and localized area of severe damage. On the other hand, cases with cam impingement showed a diffuse area of involvement affecting a larger surface of the acetabular cartilage, with degenerative changes, superficial erosions and some discontinuities. A small biopsy specimen of the acetabular rim including bone, cartilage and labrum from the affected zone was obtained in all cases. Histological evaluation was performed under normal and polarized light microscopy. Histological findings helped corroborate the pre-operative diagnosis and also define the unique nature of impingement and specific damage according to the type of impingement.

Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) in Femoacetabular impingement

Femoroacetabular impingement is a well-described pre-arthritic condition with two main types; cam and pincer. Studies using the open treatment for impingement have described patterns of articular cartilage wear specific to cam and pincer impingement. Assessing articular damage in the hip joint is an important component of treatment. Intravenous gadolidium allows radiologists to perform an indirect assessment of articular cartilage glycosaminoglycan (GAG) content by using a technique called dGEMRIC. Using this indirect assessment of articular cartilage, we compared the dGEMRIC indices in a group of six cam and seven pincer patients to a control group (n = 12) of asymptomatic controls that had no plain MRI findings of osteoarthritis. The superior portion of the hip joint was divided into seven regions from 9 to 3 o'clock. These regions were then subdivided into peripheral and central regions. The cam and pincer groups both had statistically lower dGEMRIC values compared to the control group. The cam group demonstrated not only peripheral but also central involvement of the joint and this was concentrated in the anterior portion of the joint. The pincer group exhibited more global hip involvement with all areas of the hip averaging a dGEMRIC index 28% less than controls. With the use of dGEMRIC more specific patterns of cartilage wear can be elicited in patients with impingement, which may improve patient selection and help better understand the progression of osteoarthithis throughout the hip joint.

Femoroacetabular impingement

Femoroacetabular impingement (FAI) is a pathomechanical concept describing the early and painful contact of morphological changes of the hip joint, both on the acetabular, and femoral head sides. These can lead clinically to symptoms of hip and groin pain, and a limited range of motion with labral, chondral and bony lesions. Pincer impingement generally involves the acetabular side of the joint where there is excessive coverage of the acetabulum, which may be focal or more diffuse. There is linear contact of the acetabulum with the head/neck junction. Cam impingement involves the femoral head side of the joint where the head is associated with bony excrescences and is aspheric. The aspheric femoral head jams into the acetabulum. Imaging appearances are reviewed below. This type is evident in young males in the second and third decades. The main features of FAI are described.

Triple innominate osteotomy for Legg-Calvé-Perthes disease in children: does the lateral coverage change with time?

Triple innominate osteotomy (TIO) is one of the modalities of surgical containment in Legg-Calvé-Perthes disease (LCPD). However, overcoverage with TIO can lead to pincer impingement.

[Femoroacetabular impingement: trigger for the development of coxarthrosis]

Femoroacetabular impingement (FAI) is frequent; the estimated prevalence ranges between 10 and 15%. Our 10-years experience strongly suggests that FAI leads to osteoarthritis. Isolated acetabular or femoral abnormalities are rare, even though in women acetabular and in men femoral abnormalities predominate. Normal radiographs do not exclude the presence of FAI. Symptoms are related to the degree of deformity and occur earlier in the presence of activities requiring high levels of motion. The majority of patients with FAI are under the age of 40 years.In contrast to impingement in total hip replacement, the natural hip is under much higher constraint, not allowing to escape from impingement-induced shear forces by subluxation or complete dislocation. FAI-induced shear forces due to an aspherical femoral head/neck (cam type) are therefore high, causing outside-in damage with cleavage lesions of the acetabular cartilage by forced flexion and internal rotation. The cartilage of the femoral head remains initially intact, which cannot be explained by the classic concept of osteoarthritis. After the femoral head has migrated into the acetabular cartilage defect, vertical forces contribute to the further course of osteoarthritis. Tears between the labrum and cartilage, as seen by MRI, are not avulsions of the labrum from the cartilage but rather outside-in avulsions of the cartilage from the labrum. In acetabular overcoverage (pincer type) the labrum is the first structure to fail and acetabular cartilage damage develops thereafter.The treatment of FAI in patients under the age of 40 years is aimed at joint preservation. The clinical result is worse in the presence of significant cartilage damage. Therefore, early appreciation of FAI and timely therapeutic intervention as well as professional and athletic adjustment are important if osteoarthritis is to be prevented.

Femoroacetabular impingement: radiographic diagnosis--what the radiologist should know

OBJECTIVE: The purpose of this article is to show the important radiographic criteria that indicate the two types of femoroacetabular impingement: pincer and cam impingement. In addition, potential pitfalls in pelvic imaging concerning femoroacetabular impingement are shown. CONCLUSION: Femoroacetabular impingement is a major cause for early "primary" osteoarthritis of the hip. It can easily be recognized on conventional radiographs of the pelvis and the proximal femur.

Range of motion in anterior femoroacetabular impingement

The range of motion of normal hips and hips with femoroacetabular impingement relative to some specific anatomic reference landmarks is unknown. We therefore described: (1) the range of motion pattern relative to landmarks; (2) the location of the impingement zones in normal and impinging hips; and (3) the influence of surgical débridement on the range of motion. We used a previously developed and validated noninvasive 3-D CT-based method for kinematic hip analysis to compare the range of motion pattern, the location of impingement, and the effect of virtual surgical reconstruction in 28 hips with anterior femoroacetabular impingement and a control group of 33 normal hips. Hips with femoroacetabular impingement had decreased flexion, internal rotation, and abduction. Internal rotation decreased with increasing flexion and adduction. The calculated impingement zones were localized in the anterosuperior quadrant of the acetabulum and were similar in the two groups and in impingement subgroups. The average improvement of internal rotation was 5.4 degrees for pincer hips, 8.5 degrees for cam hips, and 15.7 degrees for mixed impingement. This method helps the surgeon quantify the severity of impingement and choose the appropriate treatment option; it provides a basis for future image-guided surgical reconstruction in femoroacetabular impingement with less invasive techniques.

Radiographic analysis of femoroacetabular impingement with Hip2Norm-reliable and validated

The purpose of this study was to validate the accuracy, consistency, and reproducibility/reliability of a new method for correction of pelvic tilt and rotation of radiographic hip parameters for pincer type of femoroacetabular impingement on an anteroposterior pelvic radiograph. Thirty cadaver hips and 100 randomized, blinded AP pelvic radiographs were used for investigation. To detect the software accuracy, the calculated femoral head coverage and classic hip parameters determined with our software were compared to reference measurements based on CT scans or conventional radiographs in a neutral orientation as gold standard. To investigate software consistency, differences among the different parameters for each cadaver pelvis were calculated when reckoned back from a random to the neutral orientation. Intra- and interobserver comparisons were used to analyze the reliability and reproducibility of all parameters. All but two parameters showed a good-to-very good accuracy with the reference measurements. No relevant systematic errors were detected in the Bland-Altman analysis. Software consistency was good-to-very good for all parameters. A good-to-very good reliability and reproducibility was found for a substantial number of the evaluated radiographic acetabular parameters. The software appears to be an accurate, consistent, reliable, and reproducible method for analysis of acetabular pathomorphologies.

Hip damage occurs at the zone of femoroacetabular impingement

Although current concepts of anterior femoroacetabular impingement predict damage in the labrum and the cartilage, the actual joint damage has not been verified by computer simulation. We retrospectively compared the intraoperative locations of labral and cartilage damage of 40 hips during surgical dislocation for cam or pincer type femoroacetabular impingement (Group I) with the locations of femoroacetabular impingement in 15 additional hips using computer simulation (Group II). We found no difference between the mean locations of the chondrolabral damage of Group I and the computed impingement zone of Group II. The standard deviation was larger for measures of articular damage from Group I in comparison to the computed values of Group II. The most severe hip damage occurred at the zone of highest probability of femoroacetabular impact, typically in the anterosuperior quadrant of the acetabulum for both cam and pincer type femoroacetabular impingements. However, the extent of joint damage along the acetabular rim was larger intraoperatively than that observed on the images of the 3-D joint simulations. We concluded femoroacetabular impingement mechanism contributes to early osteoarthritis including labral lesions. LEVEL OF EVIDENCE: Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Femoroacetabular impingement: radiographic diagnosis- what the radiologist should know

OBJECTIVE: The purpose of this article is to show the important radiographic criteria that indicate the two types of femoroacetabular impingement: pincer and cam impingement. In addition, potential pitfalls in pelvic imaging concerning femoroacetabular impingement are shown. CONCLUSION: Femoroacetabular impingement is a major cause for early "primary" osteoarthritis of the hip. It can easily be recognized on conventional radiographs of the pelvis and the proximal femur.

Cartilage damage in femoroacetabular impingement (FAI): preliminary results on comparison of standard diagnostic vs delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC)

OBJECTIVES: To study the three-dimensional (3D) T1 patterns in different types of femoroacetabular impingement (FAI) by utilizing delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) and subsequent 3D T1 mapping. We used standard grading of OA by Tonnis grade on standard radiographs and morphological grading of cartilage in MRI for comparative analysis. METHODS: dGEMRIC was obtained from ten asymptomatic young-adult volunteers and 26 symptomatic FAI patients. MRI included the routine hip protocol and a dual-flip angle (FA) 3D gradient echo (GRE) sequence utilizing inline T1 measurement. Cartilage was morphologically classified from the radial images based on the extent of degeneration as: no degeneration, degeneration zone measuring <0.75 cm from the rim, >0.75 cm, or total loss. T1 findings were evaluated and correlated. RESULTS: All FAI types revealed remarkably lower T1 mean values in comparison to asymptomatic volunteers in all regions of interest. Distribution of the T1 dGEMRIC values was in accordance with the specific FAI damage pattern. In cam-types (n=6) there was a significant drop (P<0.05) of T1 in the anterior to superior location. In pincer-types (n=7), there was a generalized circumferential decrease noted. High inter-observer (intra-observer) reliability was noted for T1 assessment using intra-class correlation (ICC):intra-class coefficient=0.89 (0.95). CONCLUSIONS: We conclude that a pattern of zonal T1 variation does seem to exist that is unique for different sub-groups of FAI. The FA GRE approach to perform 3D T1 mapping has a promising role for further studies of standard MRI and dGEMRIC in the hip joint.

Conventional radiographs to assess femoroacetabular impingement

Femoroacetabular impingement (FAI) is a pathologic condition of the hip joint in young adults that, if untreated, leads to end-stage osteoarthritis. It is characterized by early pathologic contact between primary osseous prominences of the acetabular rim (so-called pincer FAI) and/or the femoral head-neck junction (cam FAI). Conventional radiographs are often considered normal because classic radiographic signs of osteoarthritis are not present initially. The physician should be aware of the radiographic features for both types of impingement to recognize subtle pathologies.

The effects of impingement and dysplasia on stress distributions in the hip joint during sitting and walking: a finite element analysis

Soft tissue damage has been observed in hip joints with pathological geometries. Our primary goal was to study the relationship between morphological variations of the bony components of the hip and resultant stresses within the soft tissues of the joint during routine daily activities. The secondary goal was to find the range of morphological parameters in which stresses are minimized. Computational models of normal and pathological joints were developed based on variations of morphological parameters of the femoral head (Alpha angle) and acetabulum (CE angle). The Alpha angle was varied between 40 degrees (normal joint) and 80 degrees (cam joint). The CE angle was varied between 0 degrees (dysplastic joint) and 40 degrees (pincer joint). Dynamic loads and motions for walking and standing to sitting were applied to all joint configurations. Contact pressures and stresses were calculated and crosscompared to evaluate the influence of morphology. The stresses in the soft tissues depended strongly on the head and acetabular geometry. For the dysplastic joint, walking produced high acetabular rim stresses. Conversely, for impinging joints, standing-to-sitting activities that involved extensive motion were critical, inducing excessive distortion and shearing of the tissue-bone interface. Zones with high von Mises stresses corresponded with clinically observed damage zones in the acetabular cartilage and labrum. Hip joint morphological parameters that minimized were 20 degrees