Interpreting sources of variation in clinical gait analysis: a case study

Objective: To illustrate and discuss sources of gait deviations (experimental, genuine and intentional) during a gait analysis and how these deviations inform clinical decision making. Methods A case study of a 24-year old male diagnosed with Alkaptonuria undergoing a routine gait analysis. A 3D motion capture with the Helen-Hayes marker set was used to quantify lower-limb joint kinematics during barefoot walking along a 10 m walkway at a self-selected pace. Additional 2D video data were recorded in the sagittal and frontal plane. The patient reported no aches or pains in any joint and described his lifestyle as active. Results: Temporal-spatial parameters were within normal ranges for his age and sex. Three sources of gait deviations were identified; the posteriorly rotated pelvis was due to an experimental error and marker misplacement, the increased rotation of the pelvis in the horizontal plane was genuine and observed in both 3D gait curves and in 2D video analysis, finally the inconsistency in knee flexion/extension combined with a seemingly innocuous interest in the consequences of abnormal gait suggested an intentional gait deviation. Conclusions: Gait analysis is an important analytical tool in the management of a variety of conditions that negatively impact on movement. Experienced gait analysts have the ability to recognise genuine gait adaptations that forms part of the decision-making process for that patient. However, their role also necessitates the ability to identify and correct for experimental errors and critically evaluate when a deviation may not be genuine

Fatal acute haemolysis and methaemoglobinaemia in a man with renal failure and Alkaptonuria - Is nitisinone the solution?

Haemolysis and methaemoglobinaemia (MetHb) are rare metabolic complications that can occur in Alkaptonuria (AKU), for which there is no curative treatment. Presented is a case of a man who had AKU, and serves as a reminder of life-threatening complications that can occur with haemolysis and MetHb. This case presents an opportunity to revisit important considerations relating to the investigation and treatment of haemolysis and MetHb with a view to raising awareness, and in doing so hopefully reducing the uniformly fatal outcome. Additionally it is proposed that treatment of haemolysis and MetHb with nitisinone is considered as a potentially lifesaving treatment as it is believed that reducing the concentration of circulating homogentisic acid will reduce oxidative stress

Age related deviation of gait from normality in alkaptonuria.

Alkaptonuria is a rare metabolic disease leading to systemic changes including early and severe arthropathy which affects mobility. Due to unknown reasons, the onset of degenerative changes is delayed to around 30 years of age when both objective and subjective symptoms develop. In order to complement describing the structural changes in alkaptonuria with measures of movement function, clinical gait analysis was added to the list of assessments in 2013. The aim of this study was to describe the deviation of gait from normality as a function of age in patients with alkaptonuria. Three-dimensional movement of reflective markers attached to joints were captured during walking in 39 patients and 10 controls. Subsequent to processing the data to emphasise the shape of marker trajectories, the mean Movement Deviation Profile was generated for all participants. This single number measure gives the deviation of a patient’s gait from a distributed definition of gait normality. Results showed that gait deviation roughly follows a sigmoid profile with minimal increase of gait deviations in a younger patient group and an abrupt large increase around the second half of the 4th decade of life. Larger variations of gait deviations were found in the older group than in the younger group suggesting a complex interaction of multiple factors which determine gait function after symptoms manifest. Continued gait analysis of adults with AKU, extended to younger adults and children with AKU, is expected to complete understanding of both the natural history of alkaptonuria and how interventions can affect movement function

Rarer insights from rarer microscopies in the study of the rare bone disease AKU.

Rarer insights from rarer microscopies in the study of the rare bone disease AKU. Thurs Oct 16th 2014 Rare bone diseases meeting Stockholm A. Boyde, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK L.R. Ranganath & J.A. Gallagher, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK [email protected] We have conducted 3D microscopic studies of surgical retrieval tissue from alkaptonuria (AKU) patients, who develop severe forms of osteoarthritis (OA). The methods used include serial sectioning of decalcified material, but more importantly, methods which avoid any risk of decacification or deformation by physical sectioning. We group these methods together under the heading block or block-face microscopy. These include BSE SEM, CSLM and dynamic aperture microscopy and x-ray microtomography. We discovered marked peculiarities in AKUbone and later looked to see if some of these were replicated in non-AKU OA - and they were. These include trabecular excrescences and hyperdense mineralised protrusions (HDMPs) from the tidemark mineralising front in articular calcified cartilage. Thus the rare disease AKU gives insights into disease mechanisms and consequences in a very common disease, OA. At QMUL, we are proud of the fact that the main medical school building at the old London Hospital Medical College of the new Barts' and The London School of Medicine and Dentistry was renamed after the man who put the genetic disease AKU on the map, Archibald Garrod

Concentric lamellae - novel microanatomical structures in the articular calcified cartilage of mice.

The structure, ultrastructure and function of hyaline articular cartilage (HAC) and subchondral bone (SCB), and their involvement in the pathogenesis of osteoarthritis (OA) have been extensively researched. However, much less attention has been focused on the intervening tissue, articular calcified cartilage (ACC) and its role in the initiation and progression of OA. Using both light microscopy (LM) and transmission electron microscopy (TEM), a study of ACC in wild type (WT) mice, and mice with genetic osteoarthropathies (AKU) was undertaken to further understand the role played by ACC in the early stages of OA.Tibio-femoral joints were obtained from BALB/c WT and BALB/c AKU mice aged between 7 and 69 weeks. One joint was processed for routine histological analysis. The tip of the medial femoral condyle (MFC), which contained HAC, ACC, and SCB, was dissected from the contra-lateral joint and processed for TEM.In WT and AKU mice novel microanatomical structures, designated concentric lamellae, were identified surrounding chondrocytes in the ACC. The lamellae appeared to be laid down in association with advancement of the tidemark indicating they may be formed during calcification of cartilage matrix. The lamellae were associated with hypertrophic chondrocytes throughout the ACC.Novel microanatomical structures, termed concentric lamellae, which were present around hypertrophic chondrocytes in the ACC are described for the first time. Their apparent association with mineralisation, advancement of the tidemark, and greater abundance in a model of osteoarthropathy indicate their formation could be important in the pathogenesis of OA and AKU

Laser ablation machined sections permit correlative studies of HDMP by X-ray microtomography, optical and scanning electron microscopy

Purpose: Cracks in bone and articular calcified cartilage (ACC) of the subchondral plate heal by intercalation of a highly mineralised infill material which disappears with demineralisation. This material may also extruded into hyaline articular cartilage (HAC) as High Density Mineralised Protrusions (HDMPs), which may fragment and act as a cutting and grinding agent, damaging HAC from within. We wish to know more about the structure and composition of HDMPs. We have prepared very thin sections from the front face of bone blocks embedded in PMMA - which had previously been studied by backscattered electron scanning electron microscopy (BSE-SEM) and x-ray microtomography (XMT) - by the new technique of laser-ablation machining and wanted to know if this method could be applied to this rather intractable problem. Methods: Samples are subject to DESS MRI and XMT before cutting slabs for PMMA embedding. The PMMA blocks are further reduced to include regions having HDMPs, prepared by polishing for backscattered electron imaging in a scanning electron microscope (BSE SEM) and higher resolution XMT. Now the block surface in the XMT reconstruction corresponds exactly with that seen by BSE SEM. The block face is stuck to a glass slide using cyano-acrylate adhesive and placed on the ‘Tissue Surgeon’ equipment (LLS Rowiak LaserLabSolutions GmbH, Germany). This works by scanning a femtosecond pulsed 1030 nm laser through a cutting plane in the specimen. Laser energy is focussed by a high numerical aperture objective lens into a very small specimen volume and for an extremely short period, generating a high instantaneous laser flux that obliterates the specimen only at the focal spot. The focussed, pulsed laser beam is scanned along a 1mm line, and this swathe is translated in an x-y snake scan to cover the entire area of the block, which is thereby released from the slide, leaving the section stuck to the slide. Light, wet polishing on 4000 grit silicon carbide polishing paper is used to remove 1-2 μm of cutting relief from the surface of the section. The block face and the underlying few microns comprise the section after laser cutting. We examine the uncoated section on the slide in the SEM for BSE imaging. For light microscopy, we apply a coverslip using glycerol as an easily removable mounting medium which does not attack PMMA or cyanoacrylate., and can go backwards and forwards to LM methods. Polarised light microscopy is best done at this stage, before staining. Many stains work with the embedding resin left in place. Images are married using homemade software. Results: With the new method we produce and use thinner sections (e.g., in the 6 to 10µm range rather than the 50-100µm range in classical ground sections). We get these sections – undeformed, intact, undecalcified - from PMMA block surfaces, so that we may have perfect correlation with x-ray microtomography (XMT, µCT), confocal LM of the block before cutting, BSE-SEM for mineral content studies, iodine stained BSE-SEM for soft tissue histology (cells, osteoid, cartilage, ligament, tendon, periosteum etc) and with all LM methods, including staining, phase, polarised light etc. Conclusions: Laser ablation microtomy produces high quality, thin sections of both hard, mineralised and dense fibrous connective tissues of any sort – even of single thin trabeculae – which can be studied with any light microscopic method as well as BSE-SEM. One sample can be studied in both the SEM and the LM. SEM becomes an extension of the LM range of methods. We are able to perform serial sectioning of the extraordinarily-difficult-to-handle HDMP features which are usually lost, down the drain, with the decalcifying solutions rampant in run-of-the-mill histopathological laboratories. Figure: Femoral head obtained at arthroplasty from Alkaptonuria patient who suffered severe pain from osteoarthritis (case described in DOI: 10.1111/joa.12226). Combined Tetrachrome-stained and polarised light image within oval area, aligned and superimposed on BSE SEM image of iodine stained PMMA block face from which the section was cut using the Rowiak ‘TissueSurgeon’ laser microtome. HDMP = high density mineralised protrusion. HAC = hyaline articular cartilage. ACC = articular calcified cartilage

Treatment of osteoporotic fractures in alkaptonuria by teriparatide stimulates bone formation and decreases fracture rate - A report of two cases.

Two cases of advanced alkaptonuria (AKU) with co-existing osteoporosis are described. Case 1 developed multiple non-vertebral fragility fractures, while Case 2 developed vertebral fragility fractures, both refractory to bisphosphonates. Difficulties in diagnosing osteoporosis in AKU complicated by extensive calcifying and ossifying spondylosis are discussed. Both patients continued to fracture despite nitisinone therapy for metabolic control of AKU, as well as bisphosphonate antiresorptive therapy for osteoporosis. Subsequently the patients were treated with teriparatide 20 μg subcutaneous injections daily for two years, leading to reduction in fractures soon after commencing therapy in both cases. Markers of bone remodelling P1NP and CTX were stimulated. No complications due hypercalcaemia or calcification were encountered in either case. We conclude that teriparatide is an effective adjunct in the treatment of AKU when bisphosphonates prove ineffective

LONGITUDINAL SURVEY FOR HIGH DENSITY MINERALISED PROTRUSIONS IDENTIFIED BY 3D DESS MRI IN PATIENTS OF THE OSTEOARTHRITIS INITIATIVE

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