Introduction

Meniscal injuries are very common cause of knee pain and resultant attendance to the orthopaedics or sports medicine clinics. The current protocol stands at clinical examination at first contact and establishing a diagnosis with clinical indicators like joint line tenderness, McMurray's, Apley's and weight-bearing test for meniscal pathology followed by MRI scan to confirm the diagnosis. Either surgical or conservative management follows this. We aim to assess clinical examination alone provide sufficient evidence for further management of meniscal injury and does a role of MRI scan exist to corroborate the findings.

Aims. In order to release the contracture band completely without damaging normal tissues (such as the sciatic nerve) in the surgical treatment of gluteal muscle contracture (GMC), we tried to display the relationship between normal tissue and contracture bands by magnetic resonance neurography (MRN) images, and to predesign a minimally invasive surgery based on the MRN images in advance. Methods. A total of 30 patients (60 hips) were included in this study. MRN scans of the pelvis were performed before surgery. The contracture band shape and external rotation angle (ERA) of the proximal femur were also analyzed. Then, the minimally invasive GMC releasing surgery was performed based on the images and measurements, and during the operation, incision lengths, surgery duration, intraoperative bleeding, and complications were recorded; the time of the first postoperative off-bed activity was also recorded. Furthermore, the patients’ clinical functions were evaluated by means of Hip Outcome Score (HOS) and Ye et al’s objective assessments, respectively. Results. The contracture bands exhibited three typical types of shape – feather-like, striped, and mixed shapes – in MR images. Guided by MRN images, we designed minimally invasive approaches directed to each hip. These approaches resulted in a shortened incision length in each hip (0.3 cm (SD 0.1)), shorter surgery duration (25.3 minutes (SD 5.8)), less intraoperative bleeding (8.0 ml (SD 3.6)), and shorter time between the end of the operation and the patient’s first off-bed activity (17.2 hours (SD 2.0)) in each patient. Meanwhile, no serious postoperative complications occurred in all patients. The mean HOS-Sports subscale of patients increased from 71.0 (SD 5.3) to 94.83 (SD 4.24) at six months postoperatively (p < 0.001). The follow-up outcomes from all patients were “good” and “excellent”, based on objective assessments. Conclusion. Preoperative MRN analysis can be used to facilitate the determination of the relationship between contracture band and normal tissues. The minimally invasive surgical design via MRN can avoid nerve damage and improve the release effect. Cite this article: Bone Jt Open 2024;5(9):776–784

Aims

The frequency of severe femoral retroversion is unclear in patients with femoroacetabular impingement (FAI). This study aimed to investigate mean femoral version (FV), the frequency of absolute femoral retroversion, and the combination of decreased FV and acetabular retroversion (AR) in symptomatic patients with FAI subtypes.

The opposable thumb is one of the defining characteristics of human anatomy and is involved in most activities of daily life. Lack of optimal thumb motion results in pain, weakness, and decrease in quality of life. First carpometacarpal (CMC1) osteoarthritis (OA) is one of the most common sites of OA. Current clinical diagnosis and monitoring of CMC1 OA disease are primarily aided by X-ray radiography; however, many studies have reported discrepancies between radiographic evidence of CMC1 OA and patient-related outcomes of pain and disability. Radiographs lack soft-tissue contrast and are insufficient for the detection of early characteristics of OA such as synovitis, which play a key role in CMC OA disease progression. Magnetic resonance imaging (MRI) and two-dimensional ultrasound (2D-US) are alternative options that are excellent for imaging soft tissue pathology. However, MRI has high operating costs and long wait-times, while 2D-US is highly operator dependent and provides 2D images of 3D anatomical structures. Three-dimensional ultrasound imaging may be an option to address the clinical need for a rapid and safe point of care imaging device. The purpose of this research project is to validate the use of mechanically translated 3D-US in CMC OA patients to assess the measurement capabilities of the device in a clinically diverse population in comparison to MRI. Four CMC1-OA patients were scanned using the 3D-US device, which was attached to a Canon Aplio i700 US machine with a 14L5 linear transducer with a 10MHz operating frequency and 58mm. Complimentary MR images were acquired using a 3.0 T MRI system and LT 3D coronal photon dense cube fat suppression sequence was used. The volume of the synovium was segmented from both 3D-US and MR images by two raters and the measured volumes were compared to find volume percent differences. Paired sample t-test were used to determine any statistically significant differences between the volumetric measurements observed by the raters and in the measurements found using MRI vs. 3D-US. Interclass Correlation Coefficients were used to determine inter- and intra-rater reliability. The mean volume percent difference observed between the two raters for the 3D-US and MRI acquired synovial volumes was 1.77% and 4.76%, respectively. The smallest percent difference in volume found between raters was 0.91% and was from an MR image. A paired sample t-test demonstrated that there was no significant difference between the volumetric values observed between MRI and 3D-US. ICC values of 0.99 and 0.98 for 3D-US and MRI respectively, indicate that there was excellent inter-rater reliability between the two raters. A novel application of a 3D-US acquisition device was evaluated using a CMC OA patient population to determine its clinical feasibility and measurement capabilities in comparison to MRI. As this device is compatible with any commercially available ultrasound machine, it increases its accessibility and ease of use, while proving a method for overcoming some of the limitations associated with radiography, MRI, and 2DUS. 3DUS has the potential to provide clinicians with a tool to quantitatively measure and monitor OA progression at the patient's bedside

Abstract. OBJECTIVE. Flattening of the talar dome is observed clinically in haemarthropathy as structural and functional changes advance but has not been quantified yet. In order to confirm clinical observation, and assess the degree of change, morphological measurements were derived from MR images. METHODS. Four measurements were taken, using ImageJ (1.52v), from sagittal MRI projections at three locations – medial, lateral and central: Trochlear Tali Arc Length (TaAL), Talar Height (TaH), Trochlear Tali Length (TaL), and Trochlear Tali Radius (TaR). These measurements were used to generate three ratios of interest: TaR:TaAL, TaAL:TaL, and TaL:TaH. With the hypothesis of a flattening of the talar dome with haemarthropathy, it was expected that TaR:TaAL and TaL:TaH should be greater for haemophilic ankles, and TaAL:TaL should be smaller. A total of 126 MR images (ethics: MEEC 18–022) were included to assess the difference in those ratios between non-diseased ankles (33 images from 11 volunteers) and haemophilic ankles (93 images from 8 patients’ ankles). Non-diseased control measurements were compared to literature to assess the capacity of doing measurements on MRI instead of radiographs or CT. RESULTS. Reasonable agreement was found between measurements on non-diseased ankles and those from literature, with greatest variance in TaAL. The medial talus demonstrated decreases in all dimensions with haemophilia (TaR=2.4%, TaL=14.7%, TaAL=19.5% and TaH=27.8%; t-test at p<0.05), as did the lateral talus (TaR=6.2%, TaL=6.8%, TaAL=12.0% and TaH=22.4%; t-test at p<0.05). The effect on the central talus was not significant. TaAL:TaL showed talar flattening in the medial and lateral haemophilic talus (healthy medial=1.21, lateral=1.20; haemophilic medial=lateral=1.14). CONCLUSION. The results demonstrate non-uniform increased influence of haemarthropathy at the medial and lateral talar extremes, with relatively healthy measurements seen in the centre. The degree of morphological change is however progressive, differing with each haemophilic ankle. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Background. Recent studies have suggested that full-limb radiographs are more accurate and sensitive than short film radiographs for pre-operative measurement of the anatomical angles required to achieve optimal knee alignment in Total Knee Arthroplasty (TKA). However, there are drawbacks associated with their use including excess radiation to the pelvic organs, the need for specialised radiography equipment and increased cost. Given these drawbacks, we compared the use of MRI scans, a commonly performed pre-operative investigation, with short film knee radiographs for measurement of knee alignment. Objective. To investigate whether knee alignment measurements made on MRI scans correlate with those measured on short film knee radiographs in patients with osteoarthritic knees. Methods. We retrospectively reviewed short film knee radiographs and MRI scans of 50 patients with knee osteoarthritis. The plain radiographs had to be performed whilst weight bearing. The MRI scans were performed supine and non-weight bearing. The exclusion criteria included previous trauma to the knee, previous TKA and previous fracture of the lower limb. 4 angle measurements defined by The American Knee Society: alpha, beta, sigma and gamma were measured using each of the 2 modalities. Kolmogorov-Smirnov and two- tailed paired t-tests were used for statistical analysis of the results. Pearson correlation coefficient was used for the measure of dependence. Results. The alpha, beta, sigma and gamma angles obtained using the MR images were different to those obtained using short film weight bearing knee radiographs by −3°± 1° (p < 0.001), 1° ± 3° (p=0.002), 1° ± 3° (p=0.047) and 1° ± 4° (p=0.113) respectively. There was a weak correlation between the MRI based method and the radiographic method in measuring all 4 angles. Conclusions. Our results have shown that the angular measurements performed on MR images should be interpreted with caution as they may vary depending on the MRI slice selected for evaluation. The differences observed and the weak correlation between the 2 modalities may be due to the different scopes used for determining the femoral or tibial axes. The measurements obtained using the plain radiographs were interpreted using a single 2D projection of a 3D structure. However, the measurements of the MR images were evaluated using a 2D image of a slice through a 3D structure. In conclusion, the use of MRI scans for pre-operative planning in TKA may not be advisable at this stage as the angular measurements obtained using the MR images were poorly correlated to those obtained using plain radiographs

To be able to assess the biomechanical and functional effects of ankle injury and disease it is necessary to characterise healthy ankle kinematics. Due to the anatomical complexity of the ankle, it is difficult to accurately measure the Tibiotalar and Subtalar joint angles using traditional marker-based motion capture techniques. Biplane Video X-ray (BVX) is an imaging technique that allows direct measurement of individual bones using high-speed, dynamic X-rays. The objective is to develop an in-vivo protocol for the hindfoot looking at the tibiotalar and subtalar joint during different activities of living. A bespoke raised walkway was manufactured to position the foot and ankle inside the field of view of the BVX system. Three healthy volunteers performed three gait and step-down trials while capturing Biplane Video X-Ray (125Hz, 1.25ms, 80kVp and 160 mA) and underwent MR imaging (Magnetom 3T Prisma, Siemens) which were manually segmented into 3D bone models (Simpleware Scan IP, Synopsis). Bone position and orientation for the Talus, Calcaneus and Tibia were calculated by manual matching of 3D Bone models to X-Rays (DSX Suite, C-Motion, Inc.). Kinematics were calculated using MATLAB (MathWorks, Inc. USA). Pilot results showed that for the subtalar joint there was greater range of motion (ROM) for Inversion and Dorsiflexion angles during stance phase of gait and reduced ROM for Internal Rotation compared with step down. For the tibiotalar joint, Gait had greater inversion and internal rotation ROM and reduced dorsiflexion ROM when compared with step down. The developed protocol successfully calculated the in-vivo kinematics of the tibiotalar and subtalar joints for different dynamic activities of daily living. These pilot results show the different kinematic profiles between two different activities of daily living. Future work will investigate translation kinematics of the two joints to fully characterise healthy kinematics

Recently, several preliminary reports have been issued on the application of computer assistance to bone tumour surgery. Surgical navigation systems can apply three-dimensional images such as CT and MR images to intraoperative visualization. Although CT is better at describing cortical bone status, MRI is considered the best method for defining the extent of marrow involvement for bone tumours and for planning surgical resection in bone tumour surgery. There have been a few reports on the application of MR imaging to navigation-assisted bone tumour surgery through CT–MR image fusion. However, the CT–MRI fusion technique requires additional costs and exposure of the patient to radiation from the preoperative CT, as well as additional time for image fusion. Above all, the image fusion process is a kind of registration (image to image registration) that inevitably leads to registration error. Herein we describe a new method for the direct application of MR images to navigation-assisted bone tumour surgery as an alternative to CT–MRI fusion. Six patients with an orthopaedic malignancy were employed for this method during navigation-assisted tumour resection. Resorbable pin placement and rapid 3-dimensional spoiled gradient echo sequences made the direct application of MR images to computer-assisted bone tumour surgery without CT–MR image fusion possible. A paired-point registration technique was employed for patient-image registration in all patients. It took 20 min on average to set up the navigation (range 15 to 25 minutes). The mean registration error was 0.98 mm (range 0.4 to 1.7 mm). On histologic examination, distances from tumours to resection margins were in accord with preoperative plans. Mean duration of follow-up was 25.8 months (range 18 to 32 months). No patient had a local recurrence or distant metastasis at the last follow-up. Direct patient-to-MRI registration is a very useful method for bone tumour surgery, permitting the application of MR images to intraoperative visualization without any additional costs or exposure of the patient to radiation from the preoperative CT scan

An isolated avulsion fracture of the peroneus longus tendon is seldom seen and potentially can go undiagnosed using basic imaging methods during an initial emergency visit. If not managed appropriately it can lead to chronic pain, a reduced range of motions and eventually affect mobility. This article brings to light the effectiveness of managing such injuries conservatively. A 55 year old postman presented to clinic with pain over the instep of his right foot for 2 months with no history of trauma. Clinically the pain was confined to the right first metatarsophalangeal joint with occasional radiation to the calf. X-ray films did not detect any obvious bony injury. MR imaging revealed an ununited avulsion fracture of the base of the 1st metatarsal. The patient was subsequently injected with a mix of steroid and local anesthetic injections at the painful nonunion site under fluoroscopic guidance. Post procedure there was no neurovascular deficit. The patient was reviewed at three months and his pain score and functional outcome improved significantly. Moreover following our intervention, the Manchester Oxford Foot Questionnaire reduced from 33 to 0. At the one year follow up he remained asymptomatic and was discharged. The peroneus longus tendon plays a role in eversion and planter flexion of foot along with providing stabilization to arches of foot. The pattern of injury to this tendon is based on two factors one is the mechanism of insult, if injured, and second is the variation in the insertion pattern of peroneus longus tendon itself. There is no gold standard treatments by which these injuries can be managed. If conservative management fails we must also consider surgery which involves percutaneous fixation, or excision of the non-healed fracture fragment and arthrodesis. To conclude isolated avulsion fractures of peroneus longus tendon are rare injuries and it is important to raise awareness of this injury and the diagnostic and management challenges faced. In this case conservative management was a success in treating this injury however it is important to take factors such as patient selection, patient autonomy and clinical judgement into account before making the final decision

Background. Intervertebral disc degeneration (DD) is a complex age-related condition that constitutes the main risk factor for disabling back pain. DD is assessed using different traits extracted from MR imaging (MRI), normally combined to give summary measures (e.g. Pfirmann score). The aetiology of DD is poorly understood and despite its high heritability (75%), the precise genetic predisposition is yet to be defined. Genome wide association study (GWAS) is used to discover genetic variants associated with a disease or phenotype. It tests variants across the whole genome. It requires large samples to provide adequate but unfortunately there is poor availability of spine imaging data due to the high cost of MRI. We have adopted new methods to examine different MRI traits independently and use the information of those traits to boost GWAS power using specialized statistical software for jointly analyse correlated traits. Methods/Results. We examined DD MRI features disc narrowing, disc bulge, disc signal intensity and osteophyte formation in the TwinsUK cohort who had undergone T2-weighted sagittal spine MRI. GWAS were performed on the four traits. MTAG software was used to boost single trait GWAS power using the information in the other trait GWAS. 9 different loci were identified. Conclusions. Preliminary results suggest genes GDF6, SP1/SP7 are associated with individual trait signal intensity. In addition, novel associated genes with potential for shedding new light on pathogenic mechanisms are identified. Additional cohorts will be included in the design as a replication to test reproducibility of the results. Conflicts of interest: No conflicts of interest. Sources of funding: Funded by Disc4All, EU Horizon 2020, MSCA-2020-ITN-ETN GA: 955735

Abstract. Introduction. The incidence of significant acute chondral injuries with patella dislocation is around 10–15%. It is accepted that chondral procedures should only be performed in the presence of joint stability. Methodology. Patients were identified from surgeon/hospital logs. Patient demographics, lesion size and location, surgical procedure, patient reported outcome measures, post-operative MR imaging and complications were recorded. PROMs and patient satisfaction was obtained. Results. 20 knees (18 patients) were included. Mean age was 18.6 years (range; 11–39) and the mean follow-up was 16.6 months (range; 2–70). The defect locations were the lateral femoral condyle (9/20; 45%), patella (9/20; 45%), medial femoral condyle (1/20; 5%) and the trochlea (1/20; 5%). The mean defect size was 2.6cm2. Twelve knees were treated with cartilage fixation, 5 with microfracture and 3 with OATS. At follow up, the overall mean Lysholm score was 77.4 (± 17.1) with no chondral regenerative procedure being statistically superior. There was no difference in Lysholm scores between those patients having acute medial patellofemoral ligament reconstruction versus medial soft tissue plication (p=0.59). Five (25%) knees required re-operation (one arthroscopic arthrolysis; one patella chondroplasty; two removal of loose bodies; one implant adjustment). Overall 90% responded as being satisfied with surgery. Conclusion. Our aggressive pathway to identify and treat acute cartilage defects with early operative intervention and patella stabilisation has shown high rates of satisfaction and Lysholm scores with no major revisions. The full range of chondral restoration options should be considered by surgeons managing these patients

Purposes of the study: Anterior cruciate ligament (ACL) deficiency is associated with degenerative osteoarthritis especially when it is present with meniscal injury; We assessed the impact of certain aetiological factors in chondral degeneration in the ACL deficient knee. Methodology and Results: Fifty-eight patients who underwent consecutive primary arthroscopic anterior cruciate ligament reconstruction using the four strand hamstring graft between 10/06/2004 and 29/06/2006 were retrospectively analysed. Patient’s charts and radiology findings were reviewed with special attention to operative notes and preoperative knee MR imaging. Patients with knee symptoms prior to presenting injury were excluded. The mechanism of injury, the time elapsed from the original injury to anterior cruciate ligament reconstruction, associated meniscal injury, and quality of cartilage in the knee- at the time of MR imaging and ACL reconstruction were noted. Degenerative cartilage changes were graded upon reconstruction using the Outerbridge classification. The average time from Injury to MR imaging and MR to ACL reconstruction was 4.85 and 12.65 months respectively. We found a direct relationship between the time elapsed after the ACL injury and the severity of the chondral lesion (p< 0.05). Furthermore, a significant worsening in chondral degeneration of the involved knee was seen when the MR imaging and ACL reconstruction were more than 12 months apart (p< 0.01). Conclusion: We conclude that chondral lesions and degeneration are more likely to be caused by an extended period of knee instability following ACL injury as opposed to age related degeneration or direct trauma to the weight bearing area of the knee. Early reconstruction may protect the knee from chondral wear and subsequent degenerative arthritis

Purpose. To develop a low complexity highly-automated multimodal approach to segment vertebral structure and quantify mixed osteolytic/osteoblastic metastases in the rat spine using a combination of CT and MR imaging. We hypothesize that semi-automated multimodal analysis applied to 3D CT and MRI reconstructions will yield accurate and repeatable quantification of whole vertebrae affected by mixed metastases. Method. Mixed spinal metastases were developed via intra-cardiac injection of canine Ace-1 luciferase transfected prostate cancer cells in a 3 week old rnu/rnu rat. Two sequential MR images of the L1-L3 vertebral motion segments were acquired using a 1H quadrature customized birdcage coil at 60 m isotropic voxel size followed by CT imaging at a 14m isotropic voxel size. The first MR image was T1 weighted to highlight the trabecular structure to ensure accurate registration with the CT image. The second MR image was T2 weighted to optimize differentiation between bone marrow and osteolytic tumour tissue. Samples were then processed for undecalcified histology and stained with Goldners Trichrome to identify mineralized bone and unmineralized new bone formation. All images were resampled to 34.9 m and manually aligned to a global axis. This was followed by an affine registration using a Quasi Newton optimizer and a Normalized Mutual Information metric to ensure accurate registration. The whole individual vertebrae and their trabecular centrums were then segmented from the CT images using an extended version of a previously developed atlas based registration algorithm. An intensity-based thresholding method was used to segment the regions corresponding to osteoblastic tumor predominantly attached to the outside of the cortical shell. The whole vertebral segmentation from the CT was warped around the T2 weighted MR to define the bone boundaries. An intensity-based thresholding approach was then applied to the T2 weighted MR segment the osteolytic tumor. Results. The customized MR coil acquired good quality images of both the bone and soft tissue structures in the spine. The CT based automated segmentation of the whole vertebrae and the trabecular centrums yielded high volumetric concurrency (∼90%) when compared to manually refined segmentations. Automated thresholding was even more robust in segmenting the individual trabecular networks and osteolytic tumours. The automation of the osteoblastic tumor segmentation was more challenging yielding concurrencies of ∼80% when compared to manually refined segmentations. Conclusion. We successfully combined CT and μMR imaging to accurately segment mixed metastatic lesions within rat vertebrae using a highly-automated algorithm. These segmentations could readily be used for quantitative evaluation of new and existing treatments aimed at skeletal metastases or to generate finite element models to evaluate biomechanical behaviour or fracture risk

Introduction: Progression of collapse in osteonecrosis of the femoral head (ONFH) is greatly influenced by repair reactions, especially bone resorptive activity. This study was performed to test if systemic alendronate treatment, a potent inhibitor of osteoclast activity, can prevent the development of collapse in ONFH. Materials and Methods: Daily administration of oral alendronate (5mg/day) was started in 14 hips in 11 patients with ONFH (Alendronate group). At the beginning of the study (3, 6, 12 months), plain radiographs, T1-weighted MR imaging, and biochemical makers of osteoclast activity (N-telopeptide of type-I collagen) and osteoblast activity (Bone-specific alkaline phosphatase), were examined. At 12 months, MR imaging was repeated. Eleven hips in 6 patients with ONFH who did not receive alendronate administration were considered as the control group. Results: There was no significant difference with respect to gender distribution, etiology factors, initial ARCO stages, and extent of necrosis in the two groups. In the alendronate group, there was an early decrease of osteoclast activity at 3 months, with a decrease to 62% at 12 months, while the decrease of osteoblast activity was smaller with 80% at 12 months. Development of collapse was observed in 4 of the 11 hips (36%) in the control group, and in none of the 14 hips in the alendronate group. There was a significant difference of collapse development between the two groups (p=0.026, Mann-Whitney U-test). Signal change on serial MR images was observed in 5 of 9 hips (56%) in the control group, with only one of 9 hips (11%) in the alendronate group. Discussion: The low incidence of signal change on serial MR images may reflect the decrease of repair activity in the alendronate group. The present study was the first clinical trial to show that alendronate has a significant preventive effect of collapse development in patients with osteonecrosis of the femoral head

This study was designed to examine the components of the MR image of the neurocentral junction (NCJ) and to explore the discrepancy between the age of closure of the NCJ as determined by anatomic and imaging studies. MR images of one hundred and fourteen porcine NCJs were correlated with anatomic and histologic sections. Whereas gross anatomic visualization did not reveal the NCJ site, MRI was sensitive for cartilage detection and accurately determined the age of NCJ closure although it overestimated the extent of closure. Based on this study, MRI characterization of the NCJ appears reliable and the NCJ cartilage does not close until adolescence. This study examined the composition of the MR image of the neurocentral junction (NCJ) and the discrepancy between the age of closure of the NCJ as determined by anatomic and imaging studies. MRI was sensitive for cartilage detection and accurately determined the age of NCJ closure (i.e. absence of cartilage on histologic examination). MRI underestimated the extent of NCJ closure, with NCJs in the process of closure often presenting as completely open on MRI. MRI and histologic characterization of the NCJ provided better description of closure patterns than anatomic examination. Disparate NCJ development has been implicated as a potential cause of adolescent idiopathic scoliosis. Whereas autopsy studies have refuted this theory by suggesting that the NCJ closes before adolescence, MRI studies have resurrected this idea by suggesting later closure. MRI-histologic correlation suggests that the NCJ cartilage remains present until adolescence and therefore further exploration of the disparate growth hypothesis is required. Gross anatomic visualization did not reveal the NCJ site, even after removal of the periosteum. In contrast, the presence or absence of an NCJ image correlated with the presence or absence of cartilage although MRI overestimated the extent of this cartilage. Vertebrae were grossly examined for any evidence of the NCJ site. Sagittal and transverse MR images of one hundred and fourteen porcine NCJs in various stages of development (thirty-eight open, sixty-four closing, twelve closed) were correlated with anatomic and histologic sections acquired at the same position. Funding: Edmonton Orthopaedic Research Association and University of Alberta Department of Radiology and Diagnostic Imaging

Purpose of the study. To incorporate magnetic resonance (MR) image data in a finite element (FE) model to estimate intervertebral disc stress as a function of posture. Background. Determining the stresses on the intervertebral discs is important for understanding disc degeneration and developing treatment strategies. The effect of different postures on disc stress has previously been investigated through disc pressure measurements and through computational modelling. Kinematic data derived from MR images and used in an FE model may provide a non-invasive way of assessing a wide range of subjects and postures. Methods. Two-dimensional FE models of the lumbar spine were created for four subjects. Vertebral bodies were modelled as rigid bodies, the disc was modelled with an isotropic elastic annulus (E = 2.5 MPa, ν=0.4) and nucleus (E = 1 MPa, ν=0.45). The geometry was defined from MR image data obtained in the supine posture; vertebral body translation and rotation were determined from images acquired in standing and sitting. Results. The principle stress distribution in standing and sitting differed between subjects. Stress peaks occurred in different discs (L4L5 v L5S1) and in different regions of the annulus (anterior v posterior). In three subjects the compressive stress at L4L5 was largest in sitting, for the fourth subject it was largest in standing; shear stress at L4L5 was highest in sitting for all four subjects. Conclusion. Kinematic data from MR images provides a way of assessing the effect of postural change on disc stress; inter-subject differences in L4L5 compressive stress are consistent with disc pressure measurements

To investigate the histological findings for a herniated cervical intervertebral disc that produces a high intensity signal on MR images. Fifty-five herniated cervical intervertebral discs harvested from 49 patients were histologically and immunohistochemically examined. Herniated cervical intervertebral discs with a high intensity signal on axial T2 MR images were classified as a globular, linear, or mosaic type. The specimens were embedded with paraffin using standard procedures. Serial 4 μm thick cryostat sagittal sections were prepared for HE, toluidine blue, PAS, and Elastica van Gieson staining as well as immunohistochemical study. The monoclonal antibodies used were specific for human CD68, IL-1β, and TNF-α. Preoperative axial T2 MR images indicated that 3 discs had no high intensity signal and 52 discs had a high intensity signal; 22 discs were globular, 20 were linear, and 10 were mosaic. Histopathologically, high intensity signal areas in globular discs consisted of nucleus pulposus surrounded by macrophages. These macrophages and the chondrocytes around them expressed IL-1β and TNF-α. Almost all of the patients with a globular disc, had had severe radicular pain. For the linear disc patients, the fissure was observed consistent with the high intensity signal. A substance that would produce positive results for PAS staining was rarely observed. The current histological study suggests that a globular type of disc with a high intensity signal on an axial T2 MR image consisted of a nucleus pulposus. Results demonstrated that, in these herniated discs, infiltrated macrophages and chondrocytes expressed inflammatory cytokines, and these reactions were associated with radicular pain. In contrast, linear and mosaic discs showed no obvious substance corresponding with the high-intensity zone, but the fissure was observed. It appears that a high-intensity zone for a linear or mosaic type of disc suggested of a fluid-filled area and/or mucoid fluid

Introduction. Patient specific instrumentation (PSI) generates customized guides from an MRI- or CT-based preoperative plan for use in total knee arthroplasty (TKA). PSI software executes the preoperative planning process. Several manufacturers have developed proprietary PSI software for preoperative planning. It is possible that each proprietary software has a unique preoperative planning process, which may lead to variation in preoperative plans among manufactures and thus variation in the overall PSI technology. The purpose of this study was to determine whether different PSI software generate similar preoperative plans when applied to a single implant system and given identical MR images. Methods. In this prospective comparative study, we evaluated PSI preoperative plans generated by Materialise software and Zimmer Patient Specific Instruments software for 37 consecutive knees. All plans utilized the Zimmer Persona™ CR implant system and were approved by a single experienced surgeon blinded to the other software-generated preoperative plan. For each knee, the MRI reconstructions for both software programs were evaluated to qualitatively determine differences in bony landmark identification. The software-generated preoperative plans were assessed to determine differences in preoperative alignment, component sizes, and resection depth. PSI planned bone resection was compared to actual bone resection to assess the accuracy of intraoperative execution. Results. Materialise and Zimmer PSI software displayed differences in identification of bony landmarks in the femur and tibia. Zimmer software determined preoperative alignment to be 0.5° more varus (p=0.008) compared to Materialise software. Discordance in femoral component size prediction occurred in 37.8% of cases (p<0.001) with 11 cases differing by one size and 3 cases differing by two sizes. Tibial component size prediction was 32.4% discordant (p<0.001) with 12 cases differing by 1 size. In cases in which both software planned identical femoral component sizes, Zimmer software planned significantly more bone resection compared to Materialise in the medial posterior femur (1.5 mm, p<0.001) and lateral posterior femur (1.4 mm, p<0.001). Discussion. The present study suggests that there is notable variation in the PSI preoperative planning process of generating a preoperative plan from MR images. We found clinically significant differences with regard to bony landmark identification, component size selection, and predicted bone resection in the posterior femur between preoperative plans generated by two PSI software programs using identical MR images and a single implant system. Surgeons should be prepared to intraoperatively deviate from PSI selected size by 1 size. They should be aware that the inherent magnitude of error for PSI bone resection with regard to both planning and execution is within 2–3 mm. Users of PSI should acknowledge the variation in the preoperative planning process when using PSI software from different manufacturers. Manufacturers should continue to improve three-dimensional MRI reconstruction, bony landmark identification, preoperative alignment assessment, component size selection, and algorithms for bone resection in order to improve PSI preoperative planning process

Aim. The purpose of this study is to compare the pre and post-operative magnetic resonance image clarity of titanium and PEEK based cervical arthroplasty devices at the level of implantation and adjacent level discs. Methodology and Results. This is a prospective, blinded, randomised study on imaging of cervical arthroplasty devices. The pre and postoperative MRI images of 16 patients who underwent cervical arthroplasty using Prestige LP(r) (Medtronic Sofamor Danek) and NuNec(tm) Cervical Arthroplasty System (Pioneer Surgical Technology, Marquette, Mich., USA) were assessed. Two independent radiologists who were blinded and provided with a sets of random images to score using a four point Jarvick grading system. Statistical analysis was completed using SPSS 16.0 statistical package (SPSS Inc, Chicago, IL) and analysis included comparing MR image quality before and after cervical arthroplasty at the operated and adjacent levels, and in between two types of implant. The pre-operative MR image quality at operated and adjacent levels was excellent in both groups. In the post-operative images, the adjacent level visualisation was adequate in both groups without much difference in average scores. However, at operated level, the quality of MR images in the NuNec group (PEEK on PEEK articulating disc) was excellent and clear visualisation of the cord, central canal, foramen and disc. Conclusion. Previous studies have shown that titanium devices allow satisfactory monitoring of adjacent and operated levels by providing good quality MRI images. Our studies confirm that using titanium based cervical arthroplasty implants provide clear visualisation of the adjacent level, however, provide less than satisfactory images at operated level. But the PEEK devices provide excellent quality images even at the operated level, with clear visualisation of neural structures and are valuable, if one wishes to assess the adequacy of neural decompression at operated level

Introduction: Anterior knee pain is a very common presenting symptom. Fat pad syndrome is an uncommon and a difficult condition to manage. The diagnosis is usually reached after a period of physiotherapy and investigation to rule out the more common aetiologies of anterior knee pain. Patients & Methods: All patients who underwent excision of the infrapatellar fat pad following a diagnosis of Fat pad syndrome are included. Each patient was evaluated to exclude patellofemoral problems and intraarticular pathologies as the cause of anterior knee pain. Each patient underwent MR imaging and all the excised specimens were sent for histological analysis. Results: The MR imaging provided with the provisional diagnosis in all patients. All the specimens were examined by a single senior histopathologist to correlate with the provisional diagnosis. The histology confirmed Hoffa’s syndrome in 5 patients and in the remaining 15 patients a spectrum of rare diagnoses as suspected by Magnetic Resonance imaging. The more notable conditions were two synovial sarcomas, three haemangiomas and a Giant cell tumour of the tendon sheath. All patients were treated successfully with complete excision. No recurrences were recorded at the end of 3 year follow-up and all patients were symptom free. Conclusion: The work up of a patient with suspected infrapatellar fat pad syndrome must include MR imaging and the exact underlying pathology should be confirmed with histological analysis of the excised fat pad as the rare causes include soft tissue malignancy