Jan Fritz

Periprosthetic joint infection

Periprosthetic joint infections are a devastating complication after arthroplasty and are associated with substantial patient morbidity. More than 25% of revisions are attributed to these infections, which are expected to increase. The increased prevalence of obesity, diabetes, and other comorbidities are some of the reasons for this increase. Recognition of the challenge of surgical site infections in general, and periprosthetic joint infections particularly, has prompted implementation of enhanced prevention measures preoperatively (glycaemic control, skin decontamination, decolonisation, etc), intraoperatively (ultraclean operative environment, blood conservation, etc), and postoperatively (refined anticoagulation, improved wound dressings, etc). Additionally, indications for surgical management have been refined. In this Review, we assess risk factors, preventive measures, diagnoses, clinical features, and treatment options for prosthetic joint infection. An international consensus meeting about such infections identified the best practices and further research needs. Orthopaedics could benefit from enhanced preventive, diagnostic, and treatment methods.

Chronic recurrent multifocal osteomyelitis: comparison of whole-body MR imaging with radiography and correlation with clinical and laboratory data.

PURPOSE To describe whole-body magnetic resonance (MR) imaging appearance of chronic recurrent multifocal osteomyelitis (CRMO) and assess the role of MR imaging versus radiography in diagnosis of disease and correlation with clinical findings and laboratory data. MATERIALS AND METHODS Institutional review board approved this retrospective HIPAA-compliant study; informed consent was waived. T1-weighted, short inversion time inversion-recovery, and contrast material-enhanced T1-weighted whole-body MR imaging was performed and two-plane radiographs, clinical findings, and laboratory data were reviewed in 13 children (median age, 13 years) with CRMO. Lesion depiction, location, and characterization and extraskeletal abnormalities were evaluated. MR imaging findings were compared with clinical and laboratory data and radiographic results. Data analysis was performed, and diagnostic performance statistics of radiography, physical examination results, and serum inflammatory markers were calculated. General multilevel linear modeling framework was used. Odds ratios were calculated to estimate effect of age, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) level on reliabilities. Associations of ESR and CRP level with total number of lesions were assessed (chi(2) test). RESULTS MR imaging depicted 101 ill-defined edemalike osseous lesions. Most frequent anatomic sites were distal femur (21%, 21 of 101), proximal tibia (17%, 17 of 101), and distal tibia and fibula (14% each, 14 of 101). In tubular bones (70 anatomic sites), metaphysis (86%, 60 of 70) and epiphysis (67%, 47 of 70) were involved. Contiguous physeal relationship (89%, 66 of 74), periosteal reaction (48%, 48 of 101), and symmetric involvement (85%, 11 of 13) were present. MR imaging demonstrated multifocality in all patients. There were no extraskeletal abnormalities and no relationship between serum inflammatory markers and number of symptomatic anatomic sites (P = .472). Sensitivity for radiography was 0.13 (70 of 119); physical examination, 0.31 (52 of 299); and serum inflammatory markers, 0.15 (two of 13). CONCLUSION Whole-body MR imaging is useful for detection of CRMO, particularly in indeterminate cases, because it is more likely to show abnormalities.

Freehand Real-Time MRI-Guided Lumbar Spinal Injection Procedures at 1.5 T: Feasibility, Accuracy, and Safety

OBJECTIVE The purpose of this study was to test the hypothesis that freehand real-time MRI-guided lumbar spinal injection procedures are feasible, accurate, and safe when performed with a clinical open-bore 1.5-T MRI system. MATERIALS AND METHODS A retrospective analysis was made of spinal injection procedures performed over an 18-month period. Forty-nine procedures were performed on 37 patients (23 women, 14 men; mean age, 36 years; range, 18-48 years). A rapid FLASH 2D MRI sequence (TR/TE, 9.3/3.5; slice thickness, 5 mm; acquisition time, 1 second) was used for real-time needle placement with freehand technique. Data assessed were type of procedure, qualitative and quantitative image quality, dimensions of needle artifact, rate of successful drug delivery, rate of vascular uptake, time requirements, and occurrence of complications. RESULTS Among the 49 procedures, 22 (45%) were nerve root injections, 18 (37%) were facet joint injections, and nine (18%) were epidural injections. The quality of real-time FLASH 2D MR images was sufficient in all cases. Contrast-to-noise ratios were sufficiently high for good delineation of relevant structures. The needle artifact made was remarkably constant with an average overestimation of length of 1.0 +/- 0.2 [SD] mm. Drug delivery was successful in all selective nerve root injections and epidural injections. The rate of successful drug delivery was 89% (16 of 18) for facet joint injections. No complete intravascular injections occurred. The mean table time was 36 minutes (range, 23-75 minutes). The mean real-time MRI time was 38 seconds (range, 12-185 seconds). No major complications occurred. CONCLUSION We accept the hypothesis that freehand real-time MRI-guided lumbar spinal injection procedures are feasible, accurate, and safe when performed with a clinical open-bore 1.5-T MRI system. We note that real-time MRI guidance has the additional advantage of a complete absence of patient and operator exposure to ionizing radiation.

MRI-Guided Injection Procedures of the Temporomandibular Joints in Children and Adults: Technique, Accuracy, and Safety

OBJECTIVE The purpose of our study was to test the hypothesis that real-time MRI-guided, selective injection procedures of the temporomandibular joints are feasible, accurate, and safe when performed on a clinical open-bore 1.5-T MR system. MATERIALS AND METHODS A retrospective analysis of 67 injection procedures of the temporomandibular joints (55% [37/67] were therapeutic injections, 27% [18/67] were diagnostic injections, and 18% [12/67] were arthrocentesis procedures), performed in 31 patients (58% [18/31] female, 42% [13/31] male; mean age, 14 years; age range, 3-34 years), was made. Seven of 38 (18%) subjects had two temporally separate procedures. Determinations of skin entry points, puncture, and injection were performed under real-time MRI. Data were assessed for rate of successful injections, quantitative and qualitative image quality, time requirements, and occurrence of complications. RESULTS Drug delivery was successful in all procedures. The quality of real-time FLASH 2D MR images was sufficient in all cases. Real-time MRI proved to be helpful to achieve high rates of intraarticular injections. Contrast-to-noise ratios were sufficiently high for good delineation of relevant structures. Average length of time was 25 minutes (range, 16-53 minutes). No major complications occurred. CONCLUSION We accept the hypothesis that real-time MRI-guided selective injection procedures of the temporomandibular joints are feasible, accurate, and safe when performed on a clinical open-bore 1.5-T MR system.

MRI Findings in Deep and Generalized Morphea (Localized Scleroderma)

OBJECTIVE Our objective was to describe the spectrum of MRI features in patients with deep and generalized morphea. CONCLUSION Imaging features of morphea are not specific and usually overlap with those of other disorders involving the skin, fascia, and musculature, such as some types of fasciitis, myositis, and so forth. Nevertheless, the imaging features of morphea reflect pathomorphologic changes of this rare disorder and enable a complete assessment of the disease extent, including depth of infiltration and disease activity.

Spectrum of magnetic resonance imaging appearances of juvenile temporomandibular joints (tmj) in non-rheumatic children

Background: Temporomandibular joints (TMJ) are frequently involved in children with juvenile idiopathic arthritis (JIA), and gadolinium-enhanced magnetic resonance imaging (MRI) is the only modality for an early diagnosis. However, only very few data exist on the appearance of contrast-enhanced MRI of normal juvenile TMJ. Purpose: To define the spectrum of normal MRI findings of juvenile TMJ, and to assess a possible overlap with findings typical for active synovitis in JIA. Material and Methods: 96 children (192 TMJ), 51 boys and 45 girls with a median age of 7.8 years (range 3–13 years), underwent a head MRI. The presence of autoimmune disease, including JIA, was excluded via chart history, available laboratory findings, and the absence of known typical pathological MRI changes (degree of synovial enhancement, hyperintense signal on T2-weighted images in the synovia or bone marrow, and morphologic changes of the mandibular condyle) of the TMJ affected by JIA. Results: In 90 (94%) children, the TMJ showed no MRI abnormalities compatible with arthritis. In three children (3%), the only abnormal MRI finding was a small bilateral joint effusion. A further three children (3%) had a mild synovial enhancement seen on both axial and coronal MR planes in one child and only in the axial plane in the other two children. Signal hyperintensity on T2-weighted images and other corresponding characteristics of TMJ inflammation were lacking in all these six patients. Conclusion: The vast majority of juvenile TMJ in non-rheumatic children shows no MRI abnormalities. Exceptions, including a discrete enhancement of the synovial membrane (3%) or small joint effusions (3%), can occur in a minority of patients, but none of them are accompanied by other signs of inflammation or morphological changes of the TMJ.

Diagnostic and Interventional MRI of the Sacroiliac Joints Using a 1.5-T Open-Bore Magnet: A One-Stop-Shopping Approach

OBJECTIVE The objective of our study was to prospectively test the hypothesis that combined diagnostic and interventional MRI of the sacroiliac joints can be performed efficiently and effectively. SUBJECTS AND METHODS Over a 12-month period, 60 patients (32 women and 28 men; median age, 28 years; age range, 18-49 years) with chronic lower back pain suspected to originate from the sacroiliac joints were enrolled in the study. Based on diagnostic MRI findings, MR fluoroscopy-guided sacroiliac joint injections were performed in 57 (95%) patients. Diagnostic injections (35, 58.3%) were performed if nonspecific or degenerative MRI findings were present. Therapeutic injections (22, 36.7%) were performed in patients with inflammatory arthropathy. In three (5%) patients, no injections were performed. Technical effectiveness was assessed by analyzing, first, the rate of intraarticular injection; second, the time required for the procedure; third, image quality; and, fourth, occurrence of complications and clinical outcome by analyzing pain intensity changes and volume and signal intensity of sacroiliac inflammatory changes. RESULTS The rate of intraarticular injection was 90.4% (103/114). The mean length of time for the procedure was 50 minutes (range, 34-103 minutes), with exponential shortening over time (p < or = 0.001). The contrast-to-noise ratios of the needle and tissues were sufficiently different for excellent delineation of the needle. No complications occurred. Diagnostic injections identified the sacroiliac joints as generating significant pain in 46.9% (15/32) of the patients. Three months after therapeutic injections, pain intensity had decreased by 62.5% (p < or = 0.001) and the volume and relative signal intensity of inflammatory changes had decreased by 37.5% (p = 0.003) and 47.6% (p < or = 0.001), respectively. CONCLUSION We accept the hypothesis that combined diagnostic and interventional MRI of the sacroiliac joints can be performed efficiently and effectively for comprehensive diagnosis and therapy of lower back pain originating from the sacroiliac joints.

MR-guided radiofrequency ablation in a 0.2-T open MR system: technical success and technique effectiveness in 100 liver tumors.

To evaluate the feasibility and technique effectiveness of magnetic resonance (MR)‐guided radiofrequency (RF) ablation of hepatic malignancies.

Right ventricle shape and contraction patterns and relation to magnetic resonance imaging findings

Objective: To analyze and to describe the shape and contraction of the normal right ventricle (RV) as visualized by magnetic resonance imaging (MRI). Methods: Thirty normal volunteers were imaged using cine MRI in axial, short-axis, and long-axis planes. The shape and contraction of the RV were qualitatively evaluated. Quantitative evaluation of RV shape was performed by calculating the angle subtended between the planes of horizontal long-axis view (HLA) and axial view and the RV base-to-apex distance. Multiplanar reformation was used to visualize changes between corresponding views. Results: The spectrum of major RV shape (wedge, box, and round) was more variable on axial images (17%, 43%, and 23%, respectively) than on HLA images (63%, 20%, and 0%, respectively). Focal outpouching of the RV free wall was more frequent on the axial view than on the HLA view. The subtended plane angle and base-to-apex distance showed statistically significant dependence indicative of an artificially foreshortened RV in the axial view with a direct influence on RV variations. Conclusions: With increasing subtended angles, variation of the normal RV appearance is substantially higher on axial views compared with HLA views.

Augmented Reality Visualization With Image Overlay for MRI-Guided Intervention: Accuracy for Lumbar Spinal Procedures With a 1.5-T MRI System

OBJECTIVE The purpose of this study was to prospectively evaluate the accuracy of an augmented reality image overlay system in MRI-guided spinal injection procedures. MATERIALS AND METHODS An augmented reality prototype was used in conjunction with a 1.5-T MRI system. A human lumbar spine phantom was used in which 62 targets were punctured to assess the accuracy of the system. Sixty anatomic targets (facet joint, disk space, and spinal canal) were punctured to assess how the accuracy of the system translated into practice. A visualization software interface was used to compare planned needle paths and final needle locations on coregistered CT images (standard of reference). Outcome variables included entry error, angle error, depth error, target error, successful access of anatomic targets, number of needle adjustments, and time requirements. RESULTS Accuracy assessments showed entry error of 1.6 ± 0.8 mm, angle error of 1.6° ± 1.0°, depth error of 0.7 ± 0.5 mm, and target error of 1.9 ± 0.9 mm. All anatomic targets (60 of 60 insertions) were successfully punctured, including all 20 facet joints, all 20 disks, and all 20 spinal canals. Four needle adjustments (6.7%) were required. Planning of a single needle path required an average of 55 seconds. A single needle insertion required an average of 1 minute 27 seconds. CONCLUSION The augmented reality image overlay system evaluated facilitated accurate MRI guidance for successful spinal procedures in a lumbar spine model. It exhibited potential for simplifying the current practice of MRI-guided lumbar spinal injection procedures.