Pauline Walsh

Design and Evaluation of a Wearable Optical Sensor for Monitoring Seated Spinal Posture

This work describes the development and evaluation of a wearable plastic optical fiber (POF) sensor for monitoring seated spinal posture. A garment-integrated POF sensor was developed and tested on nine healthy subjects, and its performance compared to data taken simultaneously from a marker-based motion capture system. Sensor performance correlated strongly with motion-capture data with an average r of 0.913. Results show that the wearable sensor provides enough accuracy of measurement to reliably monitor seated spinal posture.

Wearable Monitoring of Seated Spinal Posture

This work describes the evaluation of a wearable plastic optical fiber (POF) sensor for monitoring seated spinal posture, as compared to a conventional expert visual analysis, and the development of a field-deployable posture monitoring system. A garment-integrated POF sensor was developed and tested on nine healthy subjects. Data from the wearable sensor were compared to data taken simultaneously from a marker-based motion capture system, for accuracy and reliability. Peak analysis of the resulting data showed a mean time error of 0.53 plusmn 0.8 s, and a mean value error of 0.64 plusmn 3.1 deg, which represents 14.5% of the average range of motion. Expert determination of transitional (good to bad) posture showed a variation of 20.9% of range of motion. These results indicate that the wearable sensor approximates the accuracy of expert visual analysis, and provides sufficient accuracy of measurement to reliably monitor seated spinal posture.

Human Chondrocyte Viability After Treatment With Local Anesthetic and/or Magnesium: Results From an In Vitro Study

PURPOSE We aimed to assess the effect on chondrocyte viability of adding magnesium to a variety of commonly available local anesthetic agents. METHODS Human chondrocytes were grown under standard culture conditions. Cells were exposed to a local anesthetic agent with the addition of magnesium (10%, 20%, or 50%). Cells were also exposed to the varying concentrations of magnesium and 0.9% saline solution. Untreated cells served as controls. The CellTiter 96 AQueous One Solution Cell Proliferation Assay was used to assess for cell viability 24 hours after exposure. One-way analysis of variance was used to test for statistical significance. RESULTS Magnesium sulfate alone was no more toxic than normal saline solution (P > .3) compared with untreated cells. The addition of magnesium to the local anesthetic agents resulted in greater cell viability than when cells were treated with a local anesthetic alone (lidocaine [P = .033], levobupivacaine [P = .007], bupivacaine [P < .001], and ropivacaine [P < .001]). CONCLUSIONS Our findings support the use of magnesium either alone or in combination with a local anesthetic rather than a local anesthetic alone, and this represents a potential strategy for the reduction of chondrocyte toxicity associated with intra-articular local anesthetic administration after arthroscopy. CLINICAL RELEVANCE The addition of magnesium to a local anesthetic results in a reduced toxic effect to the articular chondrocyte. This may represent a potential approach to intra-articular analgesia.

Statins: a potential role in the management of osteoarthritis?

Osteoarthritis is a degenerative joint disease frequently encountered in rheumatologic and orthopaedic practice. It is a progressive disease that currently available pharmacological therapy can only control the symptoms of. Non-steroidal anti-inflammatory drugs, the most preferred drug by patients, have significant side effects and the end stage treatment of osteoarthritis, in the form of joint replacement surgery, carries inherent risks to the patient. We review the potential role of statins, a drug class developed for and widely used in the treatment of hypercholesterolaemia. It is becoming clear that these drugs have more than just cholesterol lowering properties and we provide an up to date assessment of the work carried out to target osteoarthritis with these agents.

Transcriptional responses in the adaptation to ischaemia-reperfusion injury: a study of the effect of ischaemic preconditioning in total knee arthroplasty patients.

BackgroundIschaemic preconditioning (IPC) has emerged as a method of reducing ischaemia-reperfusion injury. However, the complex mechanism through which IPC elicits this protection is not fully understood. The aim of this study was to investigate the genomic response induced by IPC in muscle biopsies taken from the operative leg of total knee arthroplasty patients in order to gain insight into the IPC mechanism.MethodsTwenty patients, undergoing primary total knee arthroplasty, were randomly assigned to IPC (n = 10) and control (n = 10) groups. Patients in the IPC group received ischaemic preconditioning immediately prior to surgery. IPC was induced by three five-minute cycles of tourniquet insufflation interrupted by five-minute cycles of reperfusion. A muscle biopsy was taken from the operative knee of control and IPC-treated patients at the onset of surgery and, again, at one hour into surgery. The gene expression profile of muscle biopsies was determined using the Affymetrix Human U113 2.0 microarray system and validated using real-time polymerase chain reaction (RT-PCR). Measurements of C-reactive protein (CRP), erythrocyte sedimentation (ESR), white cell count (WCC), cytokines and haemoglobin were also made pre- and post-operatively.ResultsMicroarray analysis revealed a significant increase in the expression of important oxidative stress defence genes, immediate early response genes and mitochondrial genes. Upregulation of pro-survival genes was also observed and correlated with a downregulation of pro-apoptotic gene expression. CRP, ESR, WCC, cytokine and haemoglobin levels were not significantly different between control and IPC patients.ConclusionsThe findings of this study suggest that IPC of the lower limb in total knee arthroplasty patients induces a protective genomic response, which results in increased expression of immediate early response genes, oxidative stress defence genes and pro-survival genes. These findings indicate that ischaemic preconditioning may be of potential benefit in knee arthroplasty and other musculoskeletal conditions.

A System for Wearable Monitoring of Seated Posture in Computer Users

This work describes the evaluation of a wearable plastic optical fiber (POF) sensor for monitoring seated spinal posture, and the development of a workstation interface for the posture monitoring system. A garment-integrated POF sensor was developed and tested on nine healthy subjects. Data from the wearable sensor were compared to data taken simultaneously from a marker-based motion capture system. Peak analysis of the resulting data show a mean value error of 0.64 degrees and a mean time error of 0.53 seconds. These results show that the wearable sensor approximates the accuracy of expert visual analysis, and provides enough accuracy of measurement to reliably monitor seated spinal posture. The initial development of the system hardware and software inte rface are also described.

Marker-Based Monitoring of Seated Spinal Posture Using a Calibrated Single-Variable Threshold Model

This work, as part of a larger project developing wearable posture monitors for the work environment, seeks to monitor and model seated posture during computer use. A non-wearable marker-based optoelectronic motion capture system was used to monitor seated posture for ten healthy subjects during a calibration exercise and a typing task. Machine learning techniques were used to select overall spinal sagittal flexion as the best indicator of posture from a set of marker and vector variables. Overall flexion data from the calibration exercise were used to define a threshold model designed to classify posture for each subject, which was then applied to the typing task data. Results of the model were analysed visually by qualified physiotherapists with experience in ergonomics and posture analysis to confirm the accuracy of the calibration. The calibration formula was found to be accurate on 100% subjects. This process will be used as a comparative measure in the evaluation of several wearable posture sensors, and to inform the design of the wearable system

The chondrotoxicity of local anaesthetics: Any clinical impact?

Joint Bone Spine - In Press.Proof corrected by the author Available online since samedi 21 mai 2011

An Evaluation of the Predictive Power of Component Vector Angles for Seated Spinal Posture Monitoring

This work is part of a larger project developing wearable posture monitors for the work environment. We seek to evaluate the predictive power of individual spinal segment vector angles, towards the selection of the optimum angles for posture monitoring. A marker-based optoelectronic motion capture system was used to monitor seated posture for 9 healthy subjects during a range of motion flexion-extension exercise. Machine learning techniques were used to evaluate the prediction accuracy of the component vector angles recorded, and the range of motion for each vector angle was calculated for each subject. The overall flexion vector angle, which encompasses the entire spinal length between the C7 and L4 vertebrae, was determined to be the best predictor angle, due to its predictive accuracy and simplicity, and its relatively larger range of motion in all subjects.