Maternal behaviours and adult offspring behavioural deficits are predicted by maternal TNFα concentration in a rat model of neurodevelopmental disorders

Exposure to inflammatory stressors during fetal development is a major risk factor for neurodevelopmental disorders (NDDs) in adult offspring. Maternal immune activation (MIA), induced by infection, causes an acute increase in pro-inflammatory cytokines which can increase the risk for NDDs directly by inducing placental and fetal brain inflammation, or indirectly through affecting maternal care behaviours thereby affecting postnatal brain development. Which of these two potential mechanisms dominates in increasing offspring risk for NDDs remains unclear. Here, we show that acute systemic maternal inflammation induced by the viral mimetic polyinosinic:polycytidylic acid (poly I:C) on gestational day 15 of rat pregnancy affects offspring and maternal behaviour, offspring cognition, and expression of NDD-relevant genes in the offspring brain. Dams exposed to poly I:C elicited an acute increase in the pro-inflammatory cytokine tumour necrosis factor (TNF; referred to here as TNFα), which predicted disruption of key maternal care behaviours. Offspring of poly I:C-treated dams showed early behavioural and adult cognitive deficits correlated to the maternal TNFα response, but, importantly, not with altered maternal care. We also found interacting effects of sex and treatment on GABAergic gene expression and DNA methylation in these offspring in a brain region-specific manner, including increased parvalbumin expression in the female adolescent frontal cortex. We conclude that the MIA-induced elevation of TNFα in the maternal compartment affects fetal neurodevelopment leading to altered offspring behaviour and cognition. Our results suggest that a focus on prenatal pathways affecting fetal neurodevelopment would provide greater insights into the mechanisms underpinning the TNFα-mediated genesis of altered offspring behaviour and cognition following maternal inflammation.

Developmental programming of macrophages by early life adversity

Macrophages are central elements of all organs, where they have a multitude of physiological and pathological functions. The first macrophages are produced during fetal development, and most adult organs retain populations of fetal-derived macrophages that self-maintain without major input of hematopoietic stem cell-derived monocytes. Their developmental origins make macrophages highly susceptible to environmental perturbations experienced in early life, in particular the fetal period. It is now well recognized that such adverse developmental conditions contribute to a wide range of diseases later in life. This chapter explores the notion that macrophages are key targets of environmental adversities during development, and mediators of their long-term impact on health and disease. We first briefly summarize our current understanding of macrophage ontogeny and their biology in tissues and consider potential mechanisms by which environmental stressors may mediate fetal programming. We then review evidence for programming of macrophages by adversities ranging from maternal immune activation and diet to environmental pollutants and toxins, which have disease relevance for different organ systems. Throughout this chapter, we contemplate appropriate experimental strategies to study macrophage programming. We conclude by discussing how our current knowledge of macrophage programming could be conceptualized, and finally highlight open questions in the field and approaches to address them.

Maternal immune activation in rodent models: A systematic review of neurodevelopmental changes in gene expression and epigenetic modulation in the offspring brain

Maternal immune activation (mIA) during pregnancy is hypothesised to disrupt offspring neurodevelopment and predispose offspring to neurodevelopmental disorders such as schizophrenia. Rodent models of mIA have explored possible mechanisms underlying this paradigm and provide a vital tool for preclinical research. However, a comprehensive analysis of the molecular changes that occur in mIA-models is lacking, hindering identification of robust clinical targets. This systematic review assesses mIA-driven transcriptomic and epigenomic alterations in specific offspring brain regions. Across 118 studies, we focus on 88 candidate genes and show replicated changes in expression in critical functional areas, including elevated inflammatory markers, and reduced myelin and GABAergic signalling proteins. Further, disturbed epigenetic markers at nine of these genes support mIA-driven epigenetic modulation of transcription. Overall, our results demonstrate that current outcome measures have direct relevance for the hypothesised pathology of schizophrenia and emphasise the importance of mIA-models in contributing to the understanding of biological pathways impacted by mIA and the discovery of new drug targets.

Gestational poly(I:C) attenuates, not exacerbates, the behavioral, cytokine and mTOR changes caused by isolation rearing in a rat 'dual-hit' model for neurodevelopmental disorders

Many psychiatric illnesses have a multifactorial etiology involving genetic and environmental risk factors that trigger persistent neurodevelopmental impairments. Several risk factors have been individually replicated in rodents, to understand disease mechanisms and evaluate novel treatments, particularly for poorly-managed negative and cognitive symptoms. However, the complex interplay between various factors remains unclear. Rodent dual-hit neurodevelopmental models offer vital opportunities to examine this and explore new strategies for early therapeutic intervention. This study combined gestational administration of polyinosinic:polycytidylic acid (poly(I:C); PIC, to mimic viral infection during pregnancy) with post-weaning isolation of resulting offspring (to mirror adolescent social adversity). After in vitro and in vivo studies required for laboratory-specific PIC characterization and optimization, we administered 10 mg/kg i.p. PIC potassium salt to time-mated Lister hooded dams on gestational day 15. This induced transient hypothermia, sickness behavior and weight loss in the dams, and led to locomotor hyperactivity, elevated striatal cytokine levels, and increased frontal cortical JNK phosphorylation in the offspring at adulthood. Remarkably, instead of exacerbating the well-characterized isolation syndrome, gestational PIC exposure actually protected against a spectrum of isolation-induced behavioral and brain regional changes. Thus isolation reared rats exhibited locomotor hyperactivity, impaired associative memory and reversal learning, elevated hippocampal and frontal cortical cytokine levels, and increased mammalian target of rapamycin (mTOR) activation in the frontal cortex - which were not evident in isolates previously exposed to gestational PIC. Brains from adolescent littermates suggest little contribution of cytokines, mTOR or JNK to early development of the isolation syndrome, or resilience conferred by PIC. But notably hippocampal oxytocin, which can protect against stress, was higher in adolescent PIC-exposed isolates so might contribute to a more favorable outcome. These findings have implications for identifying individuals at risk for disorders like schizophrenia who may benefit from early therapeutic intervention, and justify preclinical assessment of whether adolescent oxytocin manipulations can modulate disease onset or progression.

Poly(I:C) source, molecular weight and endotoxin contamination affect dam and prenatal outcomes, implications for models of maternal immune activation

The viral mimetic polyinosinic:polycytidylic acid (poly(I:C)) is increasingly used to induce maternal immune activation (mIA) to model neurodevelopmental disorders (NDDs). Robust and reproducible phenotypes across studies are essential for the generation of models that will enhance our understanding of NDDs and enable the development of improved therapeutic strategies. However, differences in mIA-induced phenotypes using poly(I:C) have been widely observed, and this has prompted the reporting of useful and much needed methodological guidelines. Here, we perform a detailed investigation of molecular weight and endotoxin variations in poly(I:C) procured from two of the most commonly used suppliers, Sigma and InvivoGen. We demonstrate that endotoxin contamination and molecular weight differences in poly(I:C) composition lead to considerable variability in maternal IL-6 response in rats treated on gestational day (GD)15 and impact on fetal outcomes. Specifically, both endotoxin contamination and molecular weight predicted reductions in litter size on GD21. Further, molecular weight predicted a reduction in placental weight at GD21. While fetal body weight at GD21 was not affected by poly(I:C) treatment, male fetal brain weight was significantly reduced by poly(I:C), dependent on supplier. Our data are in agreement with recent reports of the importance of poly(I:C) molecular weight, and extend this work to demonstrate a key role of endotoxin on relevant phenotypic outcomes. We recommend that the source and batch numbers of poly(I:C) used should always be stated and that molecular weight variability and endotoxin contamination should be minimised for more robust mIA modelling.

Quantitative magnetic resonance imaging and histological hoof wall assessment of 3-year-old Quarter Horses

BACKGROUND

Few noninvasive methods are available for equine hoof wall evaluation. The highly organised wall structures and composition of proteoglycans and collagens may make this region amenable to quantitative MRI (qMRI) techniques of T1ρ and T2 mapping to identify pathology related to proteoglycan content and collagen organisation respectively.

OBJECTIVE

To establish normative T1ρ and T2 values of the equine hoof wall of 3-year-old Quarter Horses with histological comparison.

STUDY DESIGN

Cadaveric anatomical study.

METHODS

Six cadaveric left thoracic feet from 3-year-old racing Quarter Horses with no reported lameness were evaluated using T1ρ and T2 mapping. Mapping was performed at six regions of interest at the toe of each hoof including proximal and distal regions of the inner epidermis, stratum lamellatum and corium. Histology was evaluated for standard hoof morphology and proteoglycan staining.

RESULTS

T2 values of the stratum lamellatum and corium were similar (42.9 [95% CI: 41.6-44.2] ms and 44 [95% CI: 42.7-45.3] ms respectively), but both were significantly different to the inner epidermis (35.8 [95% CI: 34.5-37.1] ms, P<0.001). T1ρ values for the inner epidermis, stratum lamellatum and corium were significantly different (25.1 [95% CI: 23.1-27.1] ms, 44.4 [95% CI: 42.4-46.4] ms and 50.1 [95% CI: 48.1-52.1] ms, respectively, P<0.001). Histology demonstrated normal organised morphology. Proteoglycan staining was only visible in the stratum lamellatum and corium.

MAIN LIMITATIONS

Cadaveric study with frozen samples used.

CONCLUSIONS

Variation of qMRI metrics through the depth of the equine hoof wall was found. Although the highly ordered environment of collagen may contribute to T2 values, there was lack of evidence to support proteoglycan content as a major contributor of T1ρ values. It is possible T1ρ values had a greater dependence on total water content as the lowest values were seen in the epidermis. Additional research using qMRI is needed to determine mapping values in different disease states.

Offspring genetic effects on maternal care

Parental care is found widely across animal taxa and is manifest in a range of behaviours from basic provisioning in cockroaches to highly complex behaviours seen in mammals. The evolution of parental care is viewed as the outcome of an evolutionary cost/benefit trade-off between investing in current and future offspring, leading to the selection of traits in offspring that influence parental behaviour. Thus, level and quality of parental care are affected by both parental and offspring genetic differences that directly and indirectly influence parental care behaviour. While significant research effort has gone into understanding how parental genomes affect parental, and mostly maternal, behaviour, few studies have investigated how offspring genomes affect parental care. In this review, we bring together recent findings across different fields focussing on the mechanism and genetics of offspring effects on maternal care in mammals.

Does collagenase injection disrupt or digest the Dupuytren's cord: a magnetic resonance imaging study

Collagenase clostridium histolyticum has been extensively studied as a treatment modality for Dupuytren's contracture. Its mechanism of action has been documented. It is unknown whether injected collagenase weakens the Dupuytren's cord sufficiently to cause failure during manipulation or if there is digestion and reduction in cord volume. We examined five patients with isolated contractures of the ring or middle metacarpalphalangeal (MP) joint using magnetic resonance imaging (MRI) prior to injection with collagenase and again 1 month following injection. All patients had full correction after manipulation which was maintained at follow-up. The Dupuytren's cord was evaluated with respect to volume, signal intensity, inflammatory changes and continuity. Additionally, signal intensity changes of the flexor tendons and neurovascular structures were recorded. MRI demonstrated cord discontinuity, significant reduction of cord volume and a significant increase in cord signal intensity after treatment with collagenase. There was a slight increase in flexor tendon signal intensity that was not significant. These findings suggest that there may be local chemical dissolution of the cord. Future studies may establish whether or not this will have prognostic implications in terms of correction and recurrence following collagenase injection.

LEVEL OF EVIDENCE

IV.

Magnetic resonance imaging of an equine fracture model containing stainless steel metal implants

REASONS FOR PERFORMING STUDY

Post operative imaging in subjects with orthopaedic implants is challenging across all modalities. Magnetic resonance imaging (MRI) is preferred to assess human post operative musculoskeletal complications, as soft tissue and bones are evaluated without using ionising radiation. However, with conventional MRI pulse sequences, metal creates susceptibility artefact that distorts anatomy. Assessment of the post operative equine patient is arguably more challenging due to the volume of metal present, and MRI is often not performed in horses with implants. Novel pulse sequences such as multiacquisition variable resonance image combination (MAVRIC) now provide improved visibility in the vicinity of surgical-grade implants and offer an option for imaging horses with metal implants.

OBJECTIVES

To compare conspicuity of regional anatomy in an equine fracture-repair model using MAVRIC, narrow receiver bandwidth (NBW) fast spin echo (FSE), and wide receiver bandwidth (WBW) FSE sequences.

STUDY DESIGN

Nonrandomised in vitro experiment.

METHODS

MAVRIC, NBW FSE and WBW FSE were performed on 9 cadaveric distal limbs with fractures and stainless steel implants in the third metacarpal bone and proximal phalanx. Objective measures of artefact reduction were performed by calculating the total artefact area in each transverse image as a percentage of the total anatomic area. The number of transverse images in which fracture lines were visible was tabulated for each sequence. Regional soft tissue conspicuity was assessed subjectively.

RESULTS

Overall anatomic delineation was improved using MAVRIC compared with NBW FSE; delineation of structures closest to the metal implants was improved using MAVRIC compared with WBW FSE and NBW FSE. Total artefact area was the highest for NBW FSE and lowest for MAVRIC; the total number of transverse slices with a visible fracture line was highest in MAVRIC and lowest in NBW FSE.

CONCLUSION

MAVRIC and WBW FSE are feasible additions to minimise artefact around implants.

MRI evaluation of rotational alignment and synovitis in patients with pain after total knee replacement

Component malalignment can be associated with pain following total knee replacement (TKR). Using MRI, we reviewed 50 patients with painful TKRs and compared them with a group of 16 asymptomatic controls to determine the feasibility of using MRI in evaluating the rotational alignment of the components. Using the additional soft-tissue detail provided by this modality, we also evaluated the extent of synovitis within these two groups. Angular measurements were based on the femoral transepicondylar axis and tibial tubercle. Between two observers, there was very high interobserver agreement in the measurements of all values. Patients with painful TKRs demonstrated statistically significant relative internal rotation of the femoral component (p = 0.030). There was relative internal rotation of the tibial to femoral component and combined excessive internal rotation of the components in symptomatic knees, although these results were significant only with one of the observers (p = 0.031). There was a statistically significant association between the presence and severity of synovitis and painful TKR (p < 0.001). MRI is an effective modality in evaluating component rotational alignment.

Imaging near metal with a MAVRIC-SEMAC hybrid

The recently developed multi-acquisition with variable resonance image combination (MAVRIC) and slice-encoding metal artifact correction (SEMAC) techniques can significantly reduce image artifacts commonly encountered near embedded metal hardware. These artifact reductions are enabled by applying alternative spectral and spatial-encoding schemes to conventional spin-echo imaging techniques. Here, the MAVRIC and SEMAC concepts are connected and discussed. The development of a hybrid technique that utilizes strengths of both methods is then introduced. The presented technique is shown capable of producing minimal artifact, high-resolution images near total joint replacements in a clinical setting.

Local cytokine profiles in knee osteoarthritis: elevated synovial fluid interleukin-15 differentiates early from end-stage disease

OBJECTIVE

Much of what is known about the inflammatory response in the synovial membrane (SM) of patients with osteoarthritis (OA) comes from studies of synovial tissues from end-stage disease. In this study, we sought to better characterize the inflammatory infiltrate in symptomatic patients with early signs of knee OA, and to determine how inflammatory cell populations relate to the pattern of cytokine and degradative enzyme production.

METHODS

Study populations comprised patients with degenerative meniscal tears and early cartilage thinning undergoing arthroscopic procedures (early OA) and patients undergoing total knee replacement for end-stage OA. Quantitative real-time polymerase chain reaction (PCR) was used to measure expression of SM cytokines and enzymes implicated in the pathogenesis of inflammatory arthritis and OA, as well as cell lineage-specific markers. We quantified synovial fluid (SF) cytokines and enzymes by enzyme-linked immunosorbent assay (ELISA) and SM cell populations by immunohistochemistry.

RESULTS

We found increased levels of SF interleukin-15 (IL-15) protein in the early knee OA patients when compared to end-stage OA. Both SF IL-15 protein and numbers of CD8 cells within SM correlated with matrix metalloproteinase-1 (MMP-1) and three levels. TNF-alpha, IL-6 and IL-21 were also detectable in the SF of the majority of patients, and IL-15 levels were associated with IL-6 levels.

CONCLUSION

IL-15 is elevated in early knee OA, suggesting activation of an innate immune response in the SM. The association of IL-15 expression with CD8 transcripts and MMPs implicates this cytokine in OA pathogenesis and as a candidate therapeutic target.

Augmentation of tendon healing in an intraarticular bone tunnel with use of a bone growth factor

We hypothesized that an exogenous bone growth factor could augment healing of a tendon graft in a bone tunnel in a rabbit anterior cruciate ligament-reconstruction model. Seventy rabbits underwent bilateral anterior cruciate ligament reconstructions with a semitendinosus tendon graft. One limb received a collagen sponge carrier vehicle containing a mixture of bone-derived proteins while the contralateral limb was treated with either no sponge or a sponge without bone-derived proteins. The reconstruction was evaluated at 2, 4, or 8 weeks with histologic, biomechanical, and magnetic resonance imaging analysis. Histologic analysis demonstrated that specimens treated with bone-derived proteins had a more consistent, dense interface tissue and closer apposition of new bone to the graft, with occasional formation of a fibrocartilaginous interface, when compared with control specimens. The treated specimens had significantly higher load-to-failure rates than did control specimens. Treatment with bone-derived proteins resulted in an average increase in tensile strength of 65%. The treated specimens were stronger than control specimens at each time point, but the difference was greatest at 8 weeks. On the basis of signal characteristics and new bone formation, magnetic resonance imaging was useful for predicting which limb was treated, the site of failure, and the limbs with higher load-to-failure values. This study demonstrates the potential for augmenting tendon healing in an intraarticular bone tunnel using an osteoinductive growth factor.

The relationship of the femoral origin of the anterior cruciate ligament and the distal femoral physeal plate in the skeletally immature knee. An anatomic study

We defined the anatomic relationship of the anterior cruciate ligament femoral origin to the distal femoral physis in the skeletally immature knee with use of 12 fresh-frozen human fetal specimens (ages, 20 to 36 weeks). Each specimen underwent magnetic resonance imaging, was dissected free of soft tissue, sectioned in the sagittal plane, and stained. The spatial relationship of 1) the epiphyseal side of the physeal proliferative zone to the nearest point of bony attachment of the anterior cruciate ligament and 2) the origin of the anterior cruciate ligament to the over-the-top position were measured. The same measurements were made in 13 skeletally immature knees (ages, 5 to 15 years). We found that the femoral origin of the fetal anterior cruciate ligament developed as a confluence of ligament fibers with periosteum at 20 weeks, vascular invasion into the epiphysis at 24 weeks, and establishment of a secure epiphyseal attachment by 36 weeks. In the fetus, the distance from the anterior cruciate ligament femoral origin to the epiphysis was 2.66+/-0.18 mm (range, 2.34 to 2.94). There was no significant change in this distance in adolescent specimens (2.92+/-0.68 mm; range, 2.24 to 3.62). The over-the-top position was at the level of the distal femoral physis.

Magnetic resonance imaging of the wrist

Optimal magnetic resonance (MR) imaging of the wrist requires a high field strength magnet and a dedicated wrist coil to achieve high-resolution images. Using current MR sequences, detailed images of articular cartilage and the supporting ligaments and tendons can be obtained. Evaluation of the triangular fibrocartilage as well as the extrinsic and intrinsic ligaments of the wrist is possible with thin-slice three-dimensional volumetric gradient recalled sequences. Fast inversion recovery sequences, used to achieve fat suppression in peripheral joints such as the wrist, allow for detection of acute osseous trauma, which is often radiographically occult. Cartilage-sensitive imaging allows for evaluation of conditions in the skeletally immature patient, such as chronic physeal loading in the adolescent gymnast, as well as detection of the sequelae of altered biomechanics in the adult, as in the ulnolunate impaction syndrome. Moreover, contrast-enhanced magnetic resonance angiography permits a relatively noninvasive evaluation of peripheral vascular disease, obviating the need for an intraarticular injection.

Pigmented villonodular synovitis of the hip: 2- to 23-year followup study

Pigmented villonodular synovitis affecting the hip is rare. Seven new patients are presented and 117 cases from the literature are reviewed. Among the new patients, two refused treatment; in one patient, severe bone loss was observed after a radiographic followup of 21 years; the second patient showed no radiographic changes 2 years after diagnosis. One patient underwent a synovectomy and had a recurrence 9 years later, requiring a total hip replacement. The remaining four patients underwent synovectomy and primary total hip replacement with no recurrences detected after an average followup of 13 years (range, 2-23 years). Among 117 cases published, 62 patients (53%) did not have enough information for analysis. A metaanalysis using the remaining 55 patients was done. In nine patients (16%; nine of 55) the diagnosis was made with a preoperative biopsy. Treatment consisted of synovectomy in 26 patients (47%; 26 of 55), arthroplasty in 24 (43%; 24 of 55), arthrodesis in two (4%; two of 55), and hindquarter amputation in a patient misdiagnosed as having synovial sarcoma (2%; one of 55). Two patients (4%; two of 55) were not treated. Ten patients had a recurrence (19%; 10 of 53); nine in the synovectomy group (35 %; nine of 26) and one in the joint replacement group (4%; one of 24). Synovectomy is recommended for patients with preserved articular cartilage and total hip replacement is recommended for patients with secondary osteoarthritis. Removal of all macroscopic tumors including careful curetting of the osteolytic lesions should be done as they may constitute a source of recurrence.

Imaging of the multiple-ligament-injured knee

Imaging of the multiple-ligament-injured knee requires a comprehensive assessment of ligaments, cartilage, bone, peripheral nerves, and vascular anatomy. It is imperative that the radiologist be a crucial part of the trauma team, to provide prompt diagnostic assistance without unnecessary delays in patient management. MR angiography remains a promising modality to detect vascular injury and provides arteriographic assessment with little risk to the patient in a more expeditious fashion than conventional contrast angiography.

Imaging of posttraumatic and soft tissue dysfunction of the elbow

The inherent obliquity of the elbow produces a challenge to the radiologist. In the treatment of elbow trauma, comprehensive evaluation includes detection of bone, cartilage, ligament, and tendon injury. In most cases, plain radiographs remain the initial imaging mainstay for evaluation of the elbow, followed by properly performed magnetic resonance imaging with thin (1.5-2 mm) sections and appropriate pulse sequencing to provide differential contrast between subchondral bone, cartilage, and joint fluid. Vigilant attention to imaging technique obviates the need for additional intraarticular contrast agent, which converts the magnetic resonance imaging to an invasive procedure and, in many cases, increases the cost. The advent of magnetic resonance angiography has provided an important noninvasive diagnostic means to detect associated vascular injury. In addition, computed tomography imaging, particularly with concomitant three-dimensional reformations, provides comprehensive fracture assessment. Postprocessing capabilities include rotation of three-dimensional models and subtraction programs that may be useful in disclosing subtle fracture components. Finally, ultrasound increasingly is being accepted as an important imaging modality by which to detect tendinous and soft tissue injury and has the distinct advantage of being able to impart dynamic load to muscle tendon units.

Magnetic resonance evaluation of the labral capsular ligamentous complex: a pictorial review

Magnetic resonance imaging of the shoulder is a common imaging test, and in the course of routine evaluation it can provide accurate information regarding the labral capsular ligamentous complex (LCLC). Common patterns of labral injury include fraying, flap tears and labral distraction, which can be readily identified on both coronal and axial planes by paying attention to signal and morphological characteristics. Capsular and ligamentous pathology may be subtle, but is recognizable using a high-resolution technique that has differential contrast between native intra-articular fluid and the adjacent labrum and capsular restraints. Common patterns of capsular injury include a thickened, hyperintense capsule, sometimes with disruption and retraction. The inferior glenohumeral ligament is the primary stabilizer of the shoulder joint, and although failure of this structure is uncommon, the injury is easily identified. Shoulder instability is a common presentation, the diagnosis of which is dependent upon recognizing various injury patterns including Bankart lesions, reverse Bankart lesions, anterior labroligamentous periosteal sleeve avulsion (ALPSA) and failure of the inferior glenohumeral ligament.

Prosthetic radial head components and proximal radial morphology: a mismatch

A morphometric study of the proximal radius was performed with magnetic resonance imaging scans to measure the anatomic dimensions of the radial head and neck. These dimensions were then compared with the manufacturer's size specifications of commercially available titanium prosthetic radial head components to determine whether these designs adequately match the morphologic characteristics of the proximal radius. A cadaveric correlation was performed to validate the accuracy and reliability of measurements obtained from the magnetic resonance scans. The narrow intramedullary dimensions of the radial neck negated fitting of even the smallest available metallic prosthetic component stem in 18 (39%) of 46 scans reviewed (confidence interval 26% to 53%). Of the 31 male patients who underwent scanning, 4 (13%) would not be able to be fitted with a prosthetic component according to the manufacturer's technique guide (confidence interval 0% to 29%). Of the 15 female patients who underwent scanning, 14 (93%) would not able to be fitted with a prosthetic stem (confidence interval 70% to 99%). In those patients in whom the radial neck could accommodate a prosthetic stem (n = 26), there was ineffective restoration of proximal radial head length in all cases (100%, confidence interval 87% to 100%). The average shortening was 4 mm of proximal radial length (range 1 to 7 mm). Our findings reveal that the commercially available metallic radial head design may overestimate the dimensions of the radial neck. Inadequate sizing of radial head prostheses may lead to an inadvertent change in proximal radial length, with potentially adverse effects on elbow, forearm, and wrist mechanics. Newer designs taking into account these anatomic dimensions may lead to an improvement in function after reconstruction.

Injuries of the pectoralis major muscle: evaluation with MR imaging

PURPOSE

To demonstrate that magnetic resonance (MR) imaging allows evaluation of injuries of the pectoralis major muscle.

MATERIALS AND METHODS

Fifteen men underwent MR imaging after injury of the pectoralis major muscle. Most of the patients (nine of 15) were injured while lifting weights, notably bench-pressing. The injuries were evaluated for abnormal morphology and signal intensity, specifically the site of injury, degree of tearing, and amount of tendon retraction.

RESULTS

Six injuries occurred at the musculotendinous junction, and five were treated conservatively; eight of the nine cases of distal tendon avulsion were treated with primary surgical repair. The MR imaging findings were confirmed in the nine cases treated surgically. Complete tears (three of 15) were less common than partial tears (12 of 15). The sternal and clavicular heads were torn in 10 patients, only the clavicular head was torn in two patients, and only the sternal head was torn in three patients. Acute tears (10 of 15) demonstrated hemorrhage and edema, whereas chronic tears (five of 15) demonstrated fibrosis and scarring. There was a variable amount of tendon retraction.

CONCLUSION

MR imaging allows accurate evaluation of injuries of the pectoralis major muscle and enables identification of patients who would benefit from surgical repair.

Noncontrast magnetic resonance imaging of superior labral lesions. 102 cases confirmed at arthroscopic surgery

Previous studies report that noncontrast magnetic resonance imaging is limited in the evaluation of the superior glenoid labrum. From our magnetic resonance imaging database of 2552 patients, we prospectively identified 104 patients with superior labral lesions who subsequently went on to arthroscopic surgery. Magnetic resonance images were assessed to identify fraying, flap tears, bucket-handle tears, or displaced flap of fibrocartilage. The biceps tendon was also evaluated. Patients were categorized according to Snyder's classification, and the findings on the magnetic resonance images were correlated with surgical findings. One hundred of the 104 tears suspected on the images were confirmed at surgery. There were four false-positives and two false-negatives, the former reflecting one normal labrum, two meniscoid-type labra, and one sublabral foramen. With arthroscopic surgery as the standard, magnetic resonance imaging had a sensitivity of 98.0% (100 of 102), a specificity of 89.5% (34 of 38), and an accuracy of 95.7% (134 of 140) for detection of superior labral lesions. We concluded that high-resolution noncontrast magnetic resonance imaging can accurately diagnose superior labral lesions and aid in surgical management.

Multiplanar analysis of acromion morphology

To more completely describe acromion morphology and its relationship to impingement syndrome, we performed three-dimensional magnetic resonance imaging (N = 111) or computed tomography (N = 27) on 132 symptomatic shoulders. The mean patient age was 46.2 years (range, 14 to 86). Four parameters were evaluated: the angle of anterior slope of the acromion in the midsagittal and lateral-sagittal planes, lateral acromial angulation in the coronal plane, and the presence or absence of medial encroachment in the acromioclavicular joint. Twenty-five asymptomatic age-matched shoulders were used as controls. All imaging data were combined because no significant differences existed between the two imaging techniques. The mean acromion angle was 19.4 degrees in the midsagittal plane and 20 degrees in the lateral-sagittal plane. In the coronal plane, 97 (73%) acromions were neutral and 35 (27%) were downward sloping. Medial encroachment was present in 31 (24%) shoulders. Age distribution from the 2nd to 8th decade demonstrated a consistent and gradual transition from a flat acromion in the younger decades to a more hooked acromion in the older decades that was significant in both the midsagittal and lateral-sagittal planes. Furthermore, a greater percentage of patients were found to have downward angulating acromions with increasing age. Ninety-eight patients (74%) had stage II or III impingement. Of these shoulders, 39 (40%) had type I acromions, 51 (52%) type II, and 8 (8%) type III. Twenty-eight of 33 acromions with coronal lateral downward sloping had impingement, and all 31 shoulders with medial encroachment had impingement.

Magnetic resonance imaging of articular cartilage in the knee. An evaluation with use of fast-spin-echo imaging

The purpose of this study was to demonstrate that specialized magnetic resonance imaging provides an accurate assessment of lesions of the articular cartilage of the knee. Arthroscopy was used as the comparative standard. Eighty-eight patients who had an average age of thirty-eight years were evaluated with magnetic resonance imaging and subsequent arthroscopy because of a suspected meniscal or ligamentous injury. The magnetic resonance imaging was performed with a specialized sequence in the sagittal, coronal, and axial planes. Seven articular surfaces (the patellar facets, the trochlea, the femoral condyles, and the tibial plateaus) were graded prospectively on the magnetic resonance images by two independent readers with use of the 5-point classification system of Outerbridge, which was also used at arthroscopy. Six hundred and sixteen articular surfaces were assessed, and 248 lesions were identified at arthroscopy. Eighty-two surfaces had chondral softening; seventy-five, mild ulceration; fifty-three, deep ulceration, fibrillation, or a flap without exposure of subchondral bone; and thirty-eight, full-thickness wear. To simplify the statistical analysis, grades 0 and 1 were regarded as disease-negative status and grades 2, 3, and 4 were regarded as disease-positive status. When the grades that had been assigned by reader 1 were used for the analysis, magnetic resonance imaging had a sensitivity of 87 per cent (144 of 166), a specificity of 94 per cent (424 of 450), an accuracy of 92 per cent (568 of 616), a positive predictive value of 85 per cent (144 of 170), and a negative predictive value of 95 per cent (424 of 446) for the detection of a chondral lesion. Interobserver variability was minimum, as indicated by a weighted kappa statistic of 0.93 (almost perfect agreement). With use of this readily available modified magnetic resonance imaging sequence, it is possible to assess all articular surfaces of the knee accurately and thereby identify lesions that are amenable to arthroscopic treatment.

Emergent musculoskeletal magnetic resonance imaging

The role of emergent musculoskeletal magnetic resonance (MR) imaging has expanded in recent years and now includes assessment of the extent and severity of musculoskeletal infection, diagnosis of occult fractures, characterization of complex fractures, and identification of selected vascular and nerve injuries associated with hip, knee, and elbow fractures and dislocations. In the elite athlete, emergent MR assessment of musculoskeletal injury allows prompt recognition of the nature of the injury, informed decision-making regarding the need for modification of competitive activity, and early institution of therapy. When surgical intervention is required, MR imaging facilitates preoperative planning.

Magnetic resonance imaging of the Lisfranc ligament of the foot

Early recognition of subtle Lisfranc injuries is important, because deformity and disability may develop after initially unremarkable radiographs. The authors studied 23 patients (mean age, 25.4 years) with a history of midfoot trauma with both radiographs and magnetic resonance imaging (MRI). When compared with the uninjured side, diastasis on radiographs ranged from 0 to 2 mm. The MRI revealed 2 intact ligaments, 3 complete tears, and 18 partial tears. All patients with complete tears had at least 2 mm more displacement between the second metatarsal and medial cuneiform, compared with the unaffected side. Because of the presence of complete or near complete rupture, seven patients underwent surgery, and the degree of rupture was confirmed. MRI of five cadaver specimens was also performed, disclosing discrete dorsal and plantar components. MRI was found to be useful in identifying Lisfranc ligament tears. If there is clear diastasis on weightbearing radiographs, MRI is not indicated. Whereas radiographic findings may be equivocal, however, MRI may accurately disclose the degree of ligament disruption.

Different regional healing rates with the outside-in technique for meniscal repair

Fifty-one patients with meniscal repair using the outside-in technique were reassessed with second-look arthroscopic procedures (N = 15), arthrographic examination (N = 41), magnetic resonance imaging (N = 36), or a combination of these techniques. Forty-one medial and 10 lateral menisci were repaired. The average clinical follow-up was 15 months (range, 3 to 80). Forty-five of 51 patients had tears that were located in or extended into the posterior horn of the medial or lateral meniscus. Complete healing occurred in 23 menisci (45%), partial healing was observed in 16 (15 medial, 1 lateral) (32%), and no healing occurred in 12 (24%). Remarkably, in all 15 patients who had tears extending from the posterior to the middle third of the medial meniscus that were partially healed, it was always the posterior third that had not fully healed. This finding is statistically significant. In addition, the middle third of these menisci had not fully healed in five patients. No healing occurred in the two patients with tears in the posterior third of the medial meniscus. Poor healing with the outside-in technique was observed in patients with tears into the posterior horn of the medial meniscus. For tears in the middle and anterior portion of the medial meniscus, as well as all lateral meniscus tears, the outside-in technique is our current method of choice.

Use of magnetic resonance imaging in spinal trauma: indications, techniques, and utility

Magnetic resonance (MR) imaging of acute spinal injury provides excellent visualization of neurologic and soft-tissue structures in a noninvasive format. Advances in imaging-sequence techniques have made possible more rapid acquisition of images with greater spatial resolution. Appropriate selection of imaging sequences allows improved imaging and contrast of the pathologic processes involved in acute spinal trauma, including spinal cord, soft-tissue, and ligamentous injury. Three patterns of spinal cord injury have been identified. Type I is representative of acute cord hemorrhage. Type II represents spinal cord edema. Type III is a mixed hemorrhagic-edematous presentation. Correlation of MR findings with experimental and clinical spinal cord injury has given a relative predictive value to spinal cord injury patterns on MR images indicative of long-term neurologic outcome. Magnetic resonance imaging is useful in delineating soft-tissue injuries associated with spinal column trauma. Despite the improved spatial resolution of MR imaging, plain radiography and computed tomography remain the standard modalities for visualizing spinal fractures.

Arthroscopic meniscal repair with fibrin clot of complete radial tears of the lateral meniscus in the avascular zone

Peripheral lateral meniscal tears are amenable to arthroscopic meniscal repair. However, the posterolateral aspect of the lateral meniscus adjacent to the popliteus tendon is devoid of penetrating peripheral vessels and therefore difficult to heal. A complete radial split at this site is usually treated with total meniscectomy. We report five cases of a tear of the posterolateral aspect of the lateral meniscus anterior to the popliteus fossa. All patients had a radial split that extended to the popliteus tendon. In all cases, the repair was enhanced with a fibrin clot. Second-look arthroscopy showed that healing of the periphery occurred in all of the cases. All patients returned to their initial level of sports activity. Three of five patients were available for follow-up at an average of 71 months, and magnetic resonance imaging was performed at that time to assess the previously repaired meniscus. All menisci were fully healed and showed no further signs of degeneration. The ability of an exogenous fibrin clot to stimulate and support a reparative response in the avascular portion of the meniscus may represent a potential method of repair. Awareness of the relatively low healing potential of this zone and enhancement of healing opportunities should improve outcome.

The use of noncontrast magnetic resonance imaging in evaluating meniscal repair: comparison with conventional arthrography

The objective of this study was to investigate whether new and different specialized fast spin-echo techniques could be used to accentuate signal within the site of meniscal repair, obviating the need for intra-articular contrast. With the use of the frequency-selective fat suppression technique, we were able to accentuate fluid in the repair site because of the inherent extended dynamic contrast range of the technique. We performed a blinded study to correlate specialized magnetic resonance imaging (MRI) sequences with standard contrast arthrography, which was used as a standard of reference. Thirty-six patients (36 meniscal repairs) agreed to have MRI followed by contrast arthrography of the affected knee, irrespective of their clinical symptoms. We found that MRI had a very high correlation with arthrography in assessing meniscal repair, with statistical significance. In eight cases that had a second-look arthroscopy, we were able to see that MRI proved to be more accurate than arthrography in discriminating partial or complete healing. This is the first report to show that specialized noncontrast MRI sequences are more effective in evaluating the physiological state of the repaired meniscus, without artifactual distention of the joint recesses by contrast and air. Noncontrast MRI can obviate the need for arthrography in assessment of meniscal repair.

The utility of high-resolution magnetic resonance imaging in the evaluation of the triangular fibrocartilage complex of the wrist

We performed a prospective study in order to assess the utility of high-resolution magnetic resonance imaging in the detection and specific localization of tears of the triangular fibrocartilage complex. Seventy-seven patients who had pain in the wrist were studied with use of a dedicated surface coil and three-dimensional gradient-recalled techniques with a field of view of eight centimeters and a slice thickness of one millimeter. The patients had pain on the ulnar side of the wrist, ligamentous instability, occult ganglia, or a combination of these. Magnetic resonance images were assessed for radial or ulnar avulsion, or both; central defects; degenerative intrasubstance changes; and complex tears of the triangular fibrocartilage complex. Partial tears were differentiated from complete tears. The findings on the magnetic resonance images were then compared with the arthroscopic findings. Fifty-seven of the fifty-nine tears that were suspected on magnetic resonance images were confirmed with arthroscopy; the two suspected tears that were not confirmed had been interpreted as small partial tears on the magnetic resonance images. With use of arthroscopy as the standard, magnetic resonance imaging had a sensitivity of 100 per cent (fifty-seven of fifty-seven), a specificity of 90 per cent (eighteen of twenty), and an accuracy of 97 per cent (seventy-five of seventy-seven) for the detection of a tear (kappa = 0.93, p < 0.00001). Fifty-three of the fifty-seven tears were localized correctly with use of magnetic resonance imaging. With regard to the location of the tear, magnetic resonance imaging had a sensitivity of 100 per cent (fifty-three of fifty-three), a specificity of 75 per cent (eighteen of twenty-four), and an accuracy of 92 per cent (seventy-one of seventy-seven) (kappa = 0.9, p < 0.0001). We concluded that high-resolution magnetic resonance imaging permits accurate depiction and localization of tears of the triangular fibrocartilage complex. When the appropriate pulse sequence is used, magnetic resonance imaging is an accurate and effective method for the non-invasive evaluation of pain in the wrist.

Popliteomeniscal fasciculi and the unstable lateral meniscus: clinical correlation and magnetic resonance diagnosis

We hypothesize that disruption of the fascicular attachments between the popliteus and lateral meniscus can result in gross instability of the meniscus producing locking of the knee. This study brings attention to the importance of the clinical examination, and the need for clinical correlation to magnetic resonance (MR) studies. We report on three patients referred with the history of mechanical locking episodes of their knee. Initial MR examinations were all read as normal before referral to our institution. On close review of these MR examinations, popliteomeniscal fascicular disruption could be seen in each case. Each of these patients had arthroscopic-repair of these meniscal detachments. At 1-year follow-up, all patients had resolution of mechanical symptoms. Each patient had confirmation of their repair with repeat arthroscopy or MR and arthrographic examinations. An anatomic specimen was used to identify the popliteus muscle and tendon, the lateral meniscus, the antero-inferior popliteomeniscal fascicle, and the postero-superior popliteomeniscal fascicle attachments. MR images of the same anatomic specimen show both superior and inferior fasciculus attachments to the capsule. MR examples of the intact and disrupted antero-inferior and postero-superior popliteomeniscal fasciculi have been correlated to anatomic specimens to help familiarize the orthopaedic surgeon with these important stabilizing structures.

Practical management of venous thromboembolism following pelvic fractures

The management of thromboembolic complications remains one of the most controversial issues in the care of patients with pelvic and acetabular fractures. Recent studies have indicated that the incidence of proximal deep vein thrombosis is much higher than was previously believed. These patients should be managed with a formal institutional protocol that includes universal prophylaxis, supplemented in some cases by screening for deep vein thrombosis.

The detection and management of proximal deep venous thrombosis in patients with acute acetabular fractures: a follow-up report

OBJECTIVE

To determine the efficacy of a thromboprophylaxis protocol that included deep venous thrombosis (DVT) prophylaxis (subcutaneous heparin), preoperative screening with magnetic resonance venography (MRV), and therapeutic management (vena caval interruption preoperatively, therapeutic heparin anticoagulation postoperatively) when indicated.

DESIGN

Prospective, consecutive.

SETTING

Tertiary referral, teaching hospital in New York City.

PATIENTS

One hundred one patients with acutely displaced acetabular fractures.

MAIN OUTCOME MEASURE

Preoperative MRV was performed to assess vascular structures. Patients with proximal DVT received vena caval filter interruption preoperatively and therapeutic warfarin postoperatively. Patients without proximal DVT received only subcutaneous heparin preoperatively and low-dose warfarin postoperatively.

RESULTS

Forty-nine asymptomatic thrombi were identified in thirty-four of 101 patients (34 percent). Location of thrombi were in the popliteal vein in four of forty-nine patients (8 percent), superficial femoral vein in eight of forty-nine (16 percent), common femoral vein in thirteen of forty-nine (27 percent), external iliac vein in six of forty-nine (12 percent), internal iliac vein in fourteen of forty-nine (29 percent), and common iliac vein in four of forty-nine (8 percent). Thrombi were isolated to the injured extremity in twenty-six of thirty-four patients (76 percent), bilateral in four of thirty-four (12 percent), and isolated to the uninjured extremity in four of thirty-four (12 percent). Twenty-six of the thirty-four patients with proximal thrombi received preoperative vena caval filters. As a result of this protocol, only one patient (1 percent) developed a nonfatal pulmonary embolism.

CONCLUSION

MRV is a sensitive screening examination that allows the placement of inferior vena caval filters based on documented proximal thrombosis. We anticipate that preoperative DVT screening with MRV will significantly decrease the incidence of fatal pulmonary embolism in this high-risk population.

Posterolateral rotatory instability of the elbow: usefulness of MR imaging in diagnosis

PURPOSE

To evaluate the efficacy of magnetic resonance (MR) imaging in the assessment of the normal and abnormal ulnar band of the lateral collateral ligament for diagnosis of posterolateral rotatory instability.

MATERIALS AND METHODS

In nine symptomatic patients and nine asymptomatic subjects, MR imaging was performed with three-dimensional gradient-recalled and fast spin-echo sequences. The nine patients had clinical symptoms suggestive of subtle elbow instability.

RESULTS

The components of the lateral collateral ligament were identified; tears of the ulnar band were noted in all symptomatic patients. The anterior fibers of the lateral collateral ligament, including the annular ligament, were intact. All symptomatic patients subsequently underwent surgical exploration and reconstruction. Positive clinical findings were demonstrated at examination performed while the patients were under anesthesia. All tears of the ulnar band were confirmed.

CONCLUSION

With use of appropriate pulse sequences, MR imaging is an effective tool in the preoperative, noninvasive diagnosis of posterolateral rotatory instability.

Traumatic tears of the subscapularis tendon. Clinical diagnosis, magnetic resonance imaging findings, and operative treatment

The study population consisted of 14 shoulders in 13 consecutive patients with surgically confirmed isolated subscapularis tendon tears. In all but three patients, the mechanism of injury was traumatic hyperextension or external rotation of the abducted arm. All patients reported pain and weakness in the affected shoulder. Physical findings revealed limited passive range of motion at maximal internal and external rotation due to pain, weakness of internal rotation of the shoulder, and tenderness in the region of the intertubercular groove. However, these findings did not conclusively point to the subscapularis tendon as the site of injury. Preoperative interpretation of magnetic resonance imaging studies was used to diagnose tears of the subscapularis tendon in 14 shoulders and biceps tendon subluxation or dislocation in 6 shoulders. On arthroscopic examination, one patient was found to have a partial-thickness tear that was treated with arthroscopic debridement. Six shoulders had full-thickness tears of the subscapularis tendon, and seven shoulders had full-thickness tears associated with concomitant biceps tendon pathologic conditions, including subluxation, dislocation, or rupture. The full-thickness subscapularis tendon tears were repaired via an open anterior approach to the shoulder through the deltopectoral groove. Associated biceps tendon injuries were treated with tenodesis of the tendon to the intertubercular groove. Our early followup results have shown that, with proper diagnoses and surgical treatments, patients have greatly decreased pain and marked improvement in shoulder function.

Labral injuries: accuracy of detection with unenhanced MR imaging of the shoulder

PURPOSE

To prospectively assess the accuracy of unenhanced magnetic resonance (MR) imaging in the detection and localization of labral injuries.

MATERIALS AND METHODS

One hundred three patients with clinically suspected shoulder injuries were prospectively examined with unenhanced MR imaging. A combination of gradient-echo and high-resolution fast-spin-echo axial pulse sequences were used. Surgical correlation was obtained in all patients.

RESULTS

At surgery, 37 torn anterior, 36 torn superior, and 19 torn posterior labral were identified. The sensitivity for detection of these tears with MR imaging was 100%, 86%, and 74%, respectively; the specificity was 95%, 100%, and 95%, respectively. Overall, unenhanced MR imaging was 95% accurate in the detection of labral injuries.

CONCLUSION

With appropriate pulse sequences, unenhanced MR imaging of the shoulder is an accurate technique for the detection and localization of labral injuries.

Thromboembolic complications in patients with pelvic trauma

Patients with pelvic trauma are known to be at increased risk for the development of thromboembolic complications. The incidence of deep venous thrombosis in patients with pelvic fractures is 35% to 60%. Proximal deep venous thrombosis, which is most likely to result in pulmonary embolism, occurs in 25% to 35% of these patients, and almost 1/2 of all proximal thrombi will be in the pelvic veins. The incidence of symptomatic pulmonary embolism in the pelvic trauma population is 2% to 10% whereas a greater proportion of patients will have clinically silent pulmonary embolism. Fatal pulmonary embolism occurs in 0.5% to 2% of patients with pelvic trauma. The cornerstone of effective management is prophylaxis and the most commonly used forms include low dose heparin, low molecular weight heparin, mechanical devices, and in some studies, inferior vena caval filters. Based on a critical review of the literature, in algorithm is proposed for the management of thromboprophylaxis in this trauma subgroup. This includes prophylaxis, screening, and treatment when proximal thrombosis is identified. Such a systematic approach to this potentially catastrophic problem may decrease the morbidity and mortality associated with thromboembolic complications in these patients.

Osteonecrosis of the knee following arthroscopic laser meniscectomy

An unusual case of osteonecrosis of the knee following an arthroscopic laser meniscectomy is presented. The unusual presentation of the osteonecrosis and the chronology suggest that the osteonecrosis of the knee resulted from damage to the articular cartilage and subchondral bone at the time of the arthroscopic laser meniscectomy.

MR imaging of meniscal allografts: correlation with clinical and arthroscopic outcomes

PURPOSE

To correlate magnetic resonance (MR) imaging findings after meniscal transplantation with those at clinical, arthroscopic, and histologic examination.

MATERIALS AND METHODS

Twenty-four patients (29 menisci) underwent MR imaging after meniscal transplantation. Nineteen patients underwent arthroscopy, and the peripheral capsular attachment, degenerative areas, or both were sampled for biopsy. MR findings were correlated with those at clinical, arthroscopic, and histologic examination.

RESULTS

MR imaging enabled accurate assessment of allograft attachments. Fragmentation and frank extrusion were associated with full-thickness chondral loss. Allograft degeneration, indicated by an increase in signal intensity, was seen with moderate and severe chondral wear. Clinical results were worse with meniscal extrusion, with complaints of locking. Patients with mild fragmentation reported pain without locking. Histologic examination of excised allografts revealed myxomatous degeneration without immunologic reaction.

CONCLUSION

MR imaging can help assess allograft placement and articular cartilage and enable differentiation of fragmentation from extrusion. Preoperative assessment of articular cartilage is important to identify patients who may be at risk for failure.

Magnetic resonance venography to evaluate the deep venous system of the pelvis in patients who have an acetabular fracture

We performed a prospective, blinded study to assess and compare the values of preoperative contrast venography and magnetic resonance venography in the detection of deep venous thrombosis in the thigh and pelvis of forty-five consecutive patients who had a displaced acetabular fracture. The magnetic resonance venography and contrast venography were performed an average of seven days (range, one to twenty-nine days) after the injury. Twenty-four asymptomatic thrombi were identified with magnetic resonance venography in fifteen (33 percent) of the patients. Four of the thrombi were in the superficial femoral vein, nine were in the common femoral vein, one was in the external iliac vein, seven were in the internal iliac vein, and three were in the common iliac vein. Ten (42 percent) of the twenty-four thrombi were confirmed with contrast venography; nine of them were located in the thigh. The remaining fourteen thrombi (58 percent) that had been noted on magnetic resonance venography could not be seen with contrast venography because they were located either in the deep pelvic veins or in the uninjured extremity. The thrombi in the internal iliac vein were identified only with magnetic resonance venography. Twelve of the fifteen patients who had thrombi had a filter placed in the inferior vena cava preoperatively. In eight of these patients, the filter was placed because of the findings of magnetic resonance venography alone. Magnetic resonance venography resulted in a change in the therapeutic management of ten (22 per cent) of the forty-five patients. There were no pulmonary emboli. We concluded that magnetic resonance venography is superior to contrast venography for the preoperative evaluation of proximal deep venous thrombosis in patients who have an acetabular fracture. Magnetic resonance venography is non-invasive, does not require the use of contrast medium, images the proximal aspects of both lower extremities simultaneously, and, most importantly, allows for the identification of deep venous thrombosis in the pelvis.

Magnetic resonance imaging of the pelvis. New orthopaedic applications

A preliminary study of using magnetic resonance angiography to detect occult proximal thrombi in patients who had hip arthroplasty was done. Despite the presence of susceptibility artifact caused by metallic components, diagnostic visualization of thigh vessels was made in a preliminary series of 15 patients. Confirmation of all previously documented (by contrast venogram via dorsal foot vein cannulation or Doppler study) proximal thrombi was made in all 15 patients. One patient had a thrombus in the contralateral extremity that had been undetected by Doppler study; 4 additional pelvic thrombi occurred in 3 patients, which had been undocumented previously. Because magnetic resonance angiography is noninvasive, requiring no contrast agent, it has advantages over conventional venography to detect occult proximal thrombi. New fast spin echo sequences are discussed that enhance visualization of regional anatomic structures adjacent to metallic prosthetic components. Emphasis was placed on assessing the posterior soft tissue envelope in patients having recurrent dislocations after total hip arthroplasty, despite acceptable component alignment. Preliminary results show a consistent absence of a posterior pseudocapsule in patients having dislocations, as compared with control patients having no dislocations.