Magnetic Resonance Imaging of Cartilage Repair: A Review

Articular cartilage lesions are a common pathology of the knee joint, and many patients may benefit from cartilage repair surgeries that offer the chance to avoid the development of osteoarthritis or delay its progression. Cartilage repair surgery, no matter the technique, requires a noninvasive, standardized, and high-quality longitudinal method to assess the structure of the repair tissue. This goal is best fulfilled by magnetic resonance imaging (MRI). The present article provides an overview of the current state of the art of MRI of cartilage repair. In the first 2 sections, preclinical and clinical MRI of cartilage repair tissue are described with a focus on morphological depiction of cartilage and the use of functional (biochemical) MR methodologies for the visualization of the ultrastructure of cartilage repair. In the third section, a short overview is provided on the regulatory issues of the United States Food and Drug Administration (FDA) and the European Medicines Agency (EMEA) regarding MR follow-up studies of patients after cartilage repair surgeries

Endosteal biologic augmentation for surgical fixation of displaced femoral neck fractures

Objectives: To report outcomes of a cohort with displaced Femoral Neck Fractures (FNF) treated with a length/angle-stable construct augmented with an endosteal fibular allograft serving as a biologic dowel. Design: Prospective Setting: Level I Trauma Center Patients: The study group consists of twenty-seven patients with isolated FNF surgically treated by a single surgeon. Intervention: Open reduction of the femoral neck, fixed with a length- and angle stable-construct of two fully threated cannulated screws augmented with an endosteal fibular allograft serving as a biologic dowel. Main Outcome Measurements: Clinical and radiographic outcomes of the fixation construct and the viability of both the femoral head and the fibular allograft, host response to the allograft and osseous union was evaluated using a specialized sequence of contrast-enhanced MRI obtained at 3 and 12 months postoperatively. Results: This construct resulted in high union rates (89%; 24/27). Two patients suffered early catastrophic failure and one patient developed fracture non-union, all of wish underwent uneventful conversion to total hip arthroplasty. Three (11%) additional patients had removal of symptomatic implants. The clinical and radiographic outcomes were excellent. Twelve months MRIs revealed either partial or complete osseous incorporation of 86% the fibular allografts without signs of adverse reaction of the host to the allograft. Femoral head osteonecrosis segments were noted in 76% of patients on MRI, however radiographically there were no sign of osteonecrosis or segmental collapse. Conclusion: The fibular allograft reconstructs the comminuted femoral neck, and the osteointegration overtime increases the strength of the host-bone-graft interface. This added strength seems to provide the stability needed to better preserve the intra-operative reduction, obtain good outcomes and reduce the complications associated with FNF. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence

Land use change impacts on floods at the catchment scale: Challenges and opportunities for future research

Research gaps in understanding flood changes at the catchment scale caused by changes in forest management, agricultural practices, artificial drainage and terracing are identified. Potential strategies in addressing these gaps are proposed, such as complex systems approaches to link processes across time scales, long-term experiments on physical-chemical-biological process interactions, and a focus on connectivity and patterns across spatial scales. It is suggested that these strategies will stimulate new research that coherently addresses the issues across hydrology, soil and agricultural sciences, forest engineering, forest ecology and geomorphology

Spatio-Temporal Progression of Grey and White Matter Damage Following Contusion Injury in Rat Spinal Cord

Cellular mechanisms of secondary damage progression following spinal cord injury remain unclear. We have studied the extent of tissue damage from 15 min to 10 weeks after injury using morphological and biochemical estimates of lesion volume and surviving grey and white matter. This has been achieved by semi-quantitative immunocytochemical methods for a range of cellular markers, quantitative counts of white matter axonal profiles in semi-thin sections and semi-quantitative Western blot analysis, together with behavioural tests (BBB scores, ledged beam, random rung horizontal ladder and DigiGait™ analysis). We have developed a new computer-controlled electronic impactor based on a linear motor that allows specification of the precise nature, extent and timing of the impact. Initial (15 min) lesion volumes showed very low variance (1.92±0.23 mm3, mean±SD, n = 5). Although substantial tissue clearance continued for weeks after injury, loss of grey matter was rapid and complete by 24 hours, whereas loss of white matter extended up to one week. No change was found between one and 10 weeks after injury for almost all morphological and biochemical estimates of lesion size or behavioural methods. These results suggest that previously reported apparent ongoing injury progression is likely to be due, to a large extent, to clearance of tissue damaged by the primary impact rather than continuing cell death. The low variance of the impactor and the comprehensive assessment methods described in this paper provide an improved basis on which the effects of potential treatment regimes for spinal cord injury can be assessed

MRI of knee ligament injury and reconstruction

Knee ligament instability may lead to meniscal and chondral damage, resulting in early osteoarthritis. Due to its superior soft tissue contrast and avoidance of harmful ionizing radiation, MRI has become the most important imaging modality for early recognition of structural defects of the knee joint. This review aims to the understanding of MRI appearances of knee ligament structures associated with knee instability, and to review the common patterns of altered knee mechanics that lead to ligament failure. Normal anatomy of the knee ligaments, pathologic conditions, and postsurgical appearances of the anterior cruciate ligament, posterior cruciate ligament, medial collateral ligament, and posterolateral corner are described