This review briefly summarises some of the definitive studies of articular cartilage by microscopic MRI (µMRI) that were conducted with the highest spatial resolutions. The article has four major sections. The first section introduces the cartilage tissue, MRI and µMRI, and the concept of image contrast in MRI. The second section describes the characteristic profiles of three relaxation times (T. 1. , T. 2. and T. 1ρ. ) and self-diffusion in healthy articular cartilage. The third section discusses several factors that can influence the visualisation of articular cartilage and the detection of cartilage lesion by MRI and µMRI. These factors include image resolution, image analysis strategies, visualisation of the total tissue, topographical variations of the tissue properties, surface fibril ambiguity, deformation of the articular cartilage, and cartilage lesion. The final section justifies the values of multidisciplinary imaging that correlates MRI with other technical modalities, such as optical imaging. Rather than an exhaustive review to capture all activities in the literature, the studies cited in this review are merely illustrative

Introduction. MAVRIC-SL (MVSL), a multi-spectral magnetic resonance imaging (MRI) sequence [1] used for visualization of tissues near hip arthroplasty, can be accelerated by a short calibration scan [2], permitting an isotropic acquisition in a clinically feasible scan time. Decreasing the repetition time (TR) can further reduce scan time. This study evaluated the feasibility of acquiring isotropic MAVRIC-SL images (MVISO) and reduced TR isotropic MAVRIC-SL images (TRMVISO) of hip arthroplasties to elucidate the added clinical benefit of such acquisitions. Methods. Following IRB approval, MVSL, MVISO and TRMVISO images were acquired for 93 hip arthroplasties (84 subjects). Images were reviewed by 2 radiologists to evaluate clinical and image quality features. Comparison of features between scanning sequences was assessed by mixed-effects ordinal logistic regression and odds ratios (OR). Inter/intra-rater agreement was determined using Gwet's agreement coefficient (AC). Results. A calibration scan permitted acquisition of isotropic image sets in under 8 minutes. MVISO and TRMVISO had decreased blurring and improved visualization of the synovium and periprosthetic bone as compared to MVSL (p<0.001, Fig. 1). MVISO and TRMVISO improved image quality features over MVSL, OR range: 1 to 968. MVISO acquisitions also had better image quality, visualization of synovium and bone, lesion conspicuity, and decreased blurring than TRMVISO (p<0.032). Substantial to perfect (0.61 ≥ AC ≥ 1.0) agreement was found for 86% of factors evaluated by the 2 readers. Conclusions. The isotropic acquisitions displayed clinically relevant features better than MVSL, with notable improvement of blurring and overall image quality. The TRMVISO altered the image contrast and contributed to poorer visualization of synovial reactions as compared to MVISO. The study demonstrated that isotropic MAVRIC scans are clinically feasible, and that MVISO scans added clinical value through improved visualization by reducing blurring. For any tables or figures, please contact the authors directly

Introduction. Pseudotumor is a known complication of Metal-on-Metal (MOM) total hip arthroplasty (THA). MRI is usually used to visualize pseudotumor formation. However, small pseudotumors close to the THA components may not be observed using MRI due to image distortion by the interaction between the metallic objects and the magnetic fields. The CT image quality also degrades because MOM THA components can induce X-ray beam-hardening effects. Therefore, we evaluated contrast-enhanced (CE) tomosynthesis. Tomosynthesis is known as an X-ray tomography technique that provides images with fewer metal artifacts and lower X-ray doses for the patients. The aim of this report was to investigate the detectability of pseudotumors by tomosynthesis. Case Report. A 71-year-old woman had undergone unilateral cementless large-diameter MOM THA using a couple of Conserve Plus acetabular cup and Profemur Z femoral component (Wright Medical, Memphis, Tennessee) for primary arthritis of the left hip at our hospital. She presented with severe hip, groin and buttock pain and swelling at fifteen months after surgery. Therefore, she was examined MRI and tomosynthesis using Sonialvision-Safire X-ray Radiography/Fluoroscopy System (Shimadzu Corporation, Japan). Plain tomosynthesis was obtained before the contrast media injection and followed by CE-tomosynthesis. Then, subtraction tomosynthesis between plain and CE-tomosynthesis were calculated in order to increase the image contrast. The subtraction tomosynthesis image enhanced the pseudotumor visibility, which was considered to be equal to that depicted using MRI (Fig. 1 and 2). However, using MRI, cystic lesions in the pseudotumor appeared as a very high signal in the T2 weighted images, whereas CE-tomosynthesis resulted in no image contrast (Fig. 3). The tomosynthesis image resulted in less image distortion and fewer metal artifacts than MRI, even in the area close to the hip implants. Discussion. MRI results in a wide variety of soft tissue contrast when imaging pseudotumors. However, MRI produces distorted images near MOM THA components. As such, CE-tomosynthesis is a promising imaging technique for detecting small, early-stage pseudotumors. Tomosynthesis also has the advantage of delivering a lower X-ray dose to the patients and providing a better spatial resolution than CT in the coronal plane

Introduction. Fifteen percent of the primary total knee arthroplasties (TKA) fails within 20 years. Among the main causes for revision surgery are instability and patellofemoral pain. Currently, the diagnostic pathway requires various diagnostic techniques to reveal the original cause for the failed knee prosthesis and is therefore time consuming and inefficient. Accordingly, there is a growing demand for a diagnostic tool that is able to simultaneously visualize soft tissue structures, bone and TKA. Magnetic resonance imaging (MRI) is capable of visualising all the structures in the knee although a trade- off needs to be made between metal artefact reducing capacities and image quality. Low-field MRI (0.25T) results in less metal artefacts and a lower image quality compared with high-field MRI (1.5T). The aim of this study is to develop a MRI imaging guide to image the problematic TKA and to evaluate this guide by comparing low-field and high-field MRI on a case study. Method. Based on literature and current differential diagnostic pathways a guide to diagnose patellofemoral pain, instability, malposition and signs of infection or fracture with MRI was developed. Therefore, methods as Insall Salvati, patellar tilt angle and visibility of fluid and soft tissues were chosen. Visibility was scored on a VAS scale from 0 to 100mm (0mm zero visibility, 100mm excellent visibility). Subsequently, this guide is used to analyse MRI scans made of a volunteer (female, 61 years, right knee) with primary TKA (Biomet, Zimmer) in sagittal, coronal and transversal direction with a FSE PD metal artefact reducing (MAR) sequence (TE/TR 12/1030ms, slice thickness 4.0mm, FOV 260×260×120mm. 3. , matrix size 224×216) on low-field MRI (Esaote G-scan Brio, 0.25T) and with a FSE T. 1. -weighted high bandwidth MAR sequence (TE/TR 6/500ms, slice thickness 3.0mm, FOV 195×195×100mm. 3. , matrix size 320×224) on high-field MRI (Avanto 1.5T, Siemens). Scans were analysed three times by one observer and the intra observer reliability was calculated with a two-way random effects model intra class correlation coefficient (ICC). Results. Due to less metal artefacts on the low-field MRI scans the angle, distance and ratio measurements were more consistent: Insall Salvati low-field 0.97–0.99, Insall Salvati high-field 1.05–1.12, patellar tilt angle low-field 2.1–2.8°, patellar tilt angle high-field 2.4–7.6°. Over all, the VAS scores are higher on the high-field MRI scans; VAS medial collateral ligament high-field 26–45, VAS medial collateral ligament low-field 24–34, VAS popliteus tendon high-field 15–27, VAS popliteus tendon low-field 2–7. The ICC values of the VAS scores, angle measurements and ratio measurements were excellent, ICC > 0.9. The ICC values of the distance measurements were moderate, ICC > 0.6. Conclusion. MRI offers possibilities to simultaneously differentiate underlying causes of the failed knee prosthesis. The structures of interest were more clearly visible on the high-field MRI scans due to higher image contrast. The angle, distance and ratio measurements were more consistent on the low-field MRI scans due to less metal artefacts. Further research should focus on a larger group of patients with complaints after TKA to verify the analysis methods

Introduction. Advanced medical imaging techniques have allowed the understanding of the patterns of relative bone motions at human joints. 1. However, poor imaging contrasts of soft tissues have not allowed the full understanding of various glenohumeral ligaments (GHL) functions during glenohumeral joint (GHJ) manoeuvres. This is presently a significant limitation to research as these structures are said to be responsible for the passive stability of the GHJ. 2. Furthermore, the repairs of GHJ instability often take recourse to these structures. 3. Earlier studies have presented a model that numerically reconstructs or simulates GHJ motions. 4. and how the locus of bony attachment points of the GHLs on a dynamic GHJ could be numerically tagged and trailed. 5. The aim of this study was to advance these previous findings by developing an algorithm that allows the quantification of GHL lengths at any instantaneous position of the GHJ. Materials and Method. CT scan of a set of humerus and scapula was reconstructed into two individual surface meshes of interconnected nodes, each node having a unique vectorial identification in space. The two attachment nodes (a and b) of a GHL were identified on the bones. 5. Least squares geometric sphere was fitted upon the humeral head (HH) and its centre (c) and radius (r) quantified. 6. Vectors a, b and c were applied to represent the ‘dominant ligament plane’ concomitant with the 2D ‘dominant plane’ of Runciman (1993). 7. This plane defined the path through which the ligament wrapped on the HH. The point of initial or end of contact of GHL on the HH was defined as the point on HH where a line from c intercepts the ligament at 90°. Total GHL length was calculated as the sum of its three segments, namely: (1) Proximal segment – a straight line from its glenoid attachment node to the point of initial contact (2) Wrap segment – an arc of (r) radius of curvature from initial to end contact points (3) Distal segment – a straight line from end contact point to the humeral node of attachment. The wrap segment was further refined by adjusting ligament contacts along this path to the actual surface contour of the HH by integrating all the surface nodes along the path. The algorithm was tested for short incremental steps of GHJ abduction, flexion, rotation and translations on the Amadi et al's kinematics simulation model. 4. . Results. From plotted graphs of 5 simulated GHL, lengths increased or decreased smoothly as the rotations and translations were increased or decreased at a constant rate, respectively. Some GHJ motion directions resulted in contrasting stretching or folding effects on different ligaments in a mathematically reasonable manner. Conclusion. This numerical application would allow the quantification of functional loading of each GHL during simulated or reconstructed GHJ motion and hence provide understanding of how the various GHL may be treated during surgical repairs

Aims

To establish our early clinical results of a new total knee arthroplasty (TKA) tibial component introduced in 2013 and compare it to other designs in use at our hospital during the same period.

Aims

Stiffness is a common complication after total knee arthroplasty (TKA). Pathogenesis is not understood, treatment options are limited, and diagnosis is challenging. The aim of this study was to investigate if MRI can be used to visualize intra-articular scarring in patients with stiff, painful knee arthroplasties.

Objectives

Static radiostereometric analysis (RSA) using implanted markers is considered the most accurate system for the evaluation of prosthesis migration. By using CT bone models instead of markers, combined with a dynamic RSA system, a non-invasive measurement of joint movement is enabled. This method is more accurate than current 3D skin marker-based tracking systems. The purpose of this study was to evaluate the accuracy of the CT model method for measuring knee joint kinematics in static and dynamic RSA using the marker method as the benchmark.

Objectives

This study aimed to evaluate the histological and mechanical features of tendon healing in a rabbit model with second-harmonic-generation (SHG) imaging and tensile testing.

Objectives

To validate the precision of digitally reconstructed radiograph (DRR) radiostereometric analysis (RSA) and the model-based method (MBM) RSA with respect to benchmark marker-based (MM) RSA for evaluation of kinematics in the native hip joint.

Objectives

The goal of this study is to investigate the relation between indicators of osteoporosis (i.e., bone mineral density (BMD), and Cortical Index (CI)) and the complexity of a fracture of the proximal humerus as a result of a low-energy trauma.

Objectives

Inflammation of the retrocalcaneal bursa (RB) is a common clinical problem, particularly in professional athletes. RB inflammation is often treated with corticosteroid injections however a number of reports suggest an increased risk of Achilles tendon (AT) rupture. The aim of this cadaveric study was to describe the anatomical connections of the RB and to investigate whether it is possible for fluid to move from the RB into AT tissue.

Objectives

An important measure for the diagnosis and monitoring of knee osteoarthritis is the minimum joint space width (mJSW). This requires accurate alignment of the x-ray beam with the tibial plateau, which may not be accomplished in practice. We investigate the feasibility of a new mJSW measurement method from stereo radiographs using 3D statistical shape models (SSM) and evaluate its sensitivity to changes in the mJSW and its robustness to variations in patient positioning and bone geometry.

Objectives

Hips with metal-on-metal total hip arthroplasty (MoM THA) have a high rate of adverse local tissue reactions (ALTR), often associated with hypersensitivity reactions. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) measures tissue perfusion with the parameter Ktrans (volume transfer constant of contrast agent). Our purpose was 1) to evaluate the feasibility of DCE-MRI in patients with THA and 2) to compare DCE-MRI in patients with MoM bearings with metal-on-polyethylene (MoP) bearings, hypothesising that the perfusion index Ktrans in hips with MoM THA is higher than in hips with MoP THA.

The identification of the extent of neural damage in patients with acute or chronic spinal cord injury is imperative for the accurate prediction of neurological recovery. The changes in signal intensity shown on routine MRI sequences are of limited value for predicting functional outcome. Diffusion tensor imaging (DTI) is a novel radiological imaging technique which has the potential to identify intact nerve fibre tracts, and has been used to image the brain for a variety of conditions. DTI imaging of the spinal cord is currently only a research tool, but preliminary studies have shown that it holds considerable promise in predicting the severity of spinal cord injury.

This paper briefly reviews our current knowledge of this technique.

We used single-photon emission computed tomography (SPECT) to determine the long-term risk of degenerative change after reconstruction of the anterior cruciate ligament (ACL). Our study population was a prospective series of 31 patients with a mean age at injury of 27.8 years (18 to 47) and a mean follow-up of ten years (9 to 13) after bone-patellar tendon-bone reconstruction of the ACL. The contralateral normal knee was used as a control. All knees were clinically stable with high clinical scores (mean Lysholm score, 93; mean Tegner activity score, 6). Fifteen patients had undergone a partial meniscectomy and ACL reconstruction at or before reconstruction of their ACL.

In the group with an intact meniscus, clinical symptoms of osteoarthritis (OA) were found in only one patient (7%), who was also the only patient with marked isotope uptake on the SPECT scan compatible with OA. In the group which underwent a partial meniscectomy, clinical symptoms of OA were found in two patients (13%), who were among five (31%) with isotope uptake compatible with OA. Only one patient (7%) in this group had evidence of advanced OA on plain radiographs.

The risk of developing OA after ACL reconstruction in this series is very low and lower than published figures for untreated ACL-deficient knees. There is a significant increase (p < 0.05) in degenerative change in patients who had a reconstruction of their ACL and a partial meniscectomy compared with those who had a reconstruction of their ACL alone.

We report a randomised controlled trial to examine the effectiveness and cost-effectiveness of arthroscopic acromioplasty in the treatment of stage II shoulder impingement syndrome. A total of 140 patients were randomly divided into two treatment groups: supervised exercise programme (n = 70, exercise group) and arthroscopic acromioplasty followed by a similar exercise programme (n = 70, combined treatment group). The main outcome measure was self-reported pain on a visual analogue scale of 0 to 10 at 24 months, measured on the 134 patients (66 in the exercise group and 68 in the combined treatment group) for whom endpoint data were available.

An intention-to-treat analysis disclosed an improvement in both groups but without statistically significant difference in outcome between the groups (p = 0.65). The combined treatment was considerably more costly.

Arthroscopic acromioplasty provides no clinically important effects over a structured and supervised exercise programme alone in terms of subjective outcome or cost-effectiveness when measured at 24 months. Structured exercise treatment should be the basis for treatment of shoulder impingement syndrome, with operative treatment offered judiciously until its true merit is proven.

Excessive acetabular cover secondary to a retroverted acetabulum causes pincer impingement, which may cause early osteoarthritis of the hip. Our aim was to determine if there was a relationship between acetabular version and osteoarthritis of the hip. Using image processing and analysis software we studied 117 CT images of the hip in patients aged less than 65 years who had undergone a CT virtual colonoscopy. The mean CT joint space of the 18 hips with acetabular retroversion was narrower compared with the 99 hips with normal acetabular alignment (p < 0.0001). A correlation of r = 0.46 (p < 0.01) was found between right hip acetabular version and the mean right hip joint space and of r = 0.31 (p = 0.02) between left hip acetabular version and the mean left hip joint space. Acetabular retroversion is associated with radiological evidence of osteoarthritis of the hip. An understanding of the mechanical basis of osteoarthritis of the hip allows early treatment of the underlying structural abnormality and prevents progression of the degenerative condition.