The effect of femoral component rotation on the five-year outcome of cemented mobile bearing total knee arthroplasty.

PURPOSE: Performing total knee replacement, accurate alignment and neutral rotation of the femoral component are widely believed to be crucial for the ultimate success. Contrary to absolute bone referenced alignment, using a ligament balancing technique does not automatically rotate the femoral component parallel to the transepicondylar axis. In this context we established the hypothesis that rotational alignment of the femoral component parallel to the transepicondylar axis (0° ± 3°) results in better outcome than alignment outside of this range. METHODS: We analysed 204 primary cemented mobile bearing total knee replacements five years postoperatively. Femoral component rotation was measured on axial radiographs using the condylar twist angle (CTA). Knee society score, range of motion as well as subjective rating documented outcome. RESULTS: In 96 knees the femoral component rotation was within the range 0 ± 3° (neutral rotation group), and in 108 knees the five-year postoperative rotational alignment of the femoral component was outside of this range (outlier group). Postoperative CTA showed a mean of 2.8° (±3.4°) internal rotation (IR) with a range between 6° external rotation (ER) and 15° IR (CI 95). No difference with regard to subjective and objective outcome could be detected. CONCLUSION: The present work shows that there is a large given natural variability in optimal rotational orientation, in this study between 6° ER and 15° IR, with numerous co-factors determining correct positioning of the femoral component. Further studies substantiating pre- and postoperative determinants are required to complete the understanding of resulting biomechanics in primary TKA.

First-principle data-driven models for assessment of motor disorders in Parkinson’s disease

Parkinson’s disease (PD) is an increasing neurological disorder in an aging society. The motor and non-motor symptoms of PD advance with the disease progression and occur in varying frequency and duration. In order to affirm the full extent of a patient’s condition, repeated assessments are necessary to adjust medical prescription. In clinical studies, symptoms are assessed using the unified Parkinson’s disease rating scale (UPDRS). On one hand, the subjective rating using UPDRS relies on clinical expertise. On the other hand, it requires the physical presence of patients in clinics which implies high logistical costs. Another limitation of clinical assessment is that the observation in hospital may not accurately represent a patient’s situation at home. For such reasons, the practical frequency of tracking PD symptoms may under-represent the true time scale of PD fluctuations and may result in an overall inaccurate assessment. Current technologies for at-home PD treatment are based on data-driven approaches for which the interpretation and reproduction of results are problematic.  The overall objective of this thesis is to develop and evaluate unobtrusive computer methods for enabling remote monitoring of patients with PD. It investigates first-principle data-driven model based novel signal and image processing techniques for extraction of clinically useful information from audio recordings of speech (in texts read aloud) and video recordings of gait and finger-tapping motor examinations. The aim is to map between PD symptoms severities estimated using novel computer methods and the clinical ratings based on UPDRS part-III (motor examination). A web-based test battery system consisting of self-assessment of symptoms and motor function tests was previously constructed for a touch screen mobile device. A comprehensive speech framework has been developed for this device to analyze text-dependent running speech by: (1) extracting novel signal features that are able to represent PD deficits in each individual component of the speech system, (2) mapping between clinical ratings and feature estimates of speech symptom severity, and (3) classifying between UPDRS part-III severity levels using speech features and statistical machine learning tools. A novel speech processing method called cepstral separation difference showed stronger ability to classify between speech symptom severities as compared to existing features of PD speech. In the case of finger tapping, the recorded videos of rapid finger tapping examination were processed using a novel computer-vision (CV) algorithm that extracts symptom information from video-based tapping signals using motion analysis of the index-finger which incorporates a face detection module for signal calibration. This algorithm was able to discriminate between UPDRS part III severity levels of finger tapping with high classification rates. Further analysis was performed on novel CV based gait features constructed using a standard human model to discriminate between a healthy gait and a Parkinsonian gait. The findings of this study suggest that the symptom severity levels in PD can be discriminated with high accuracies by involving a combination of first-principle (features) and data-driven (classification) approaches. The processing of audio and video recordings on one hand allows remote monitoring of speech, gait and finger-tapping examinations by the clinical staff. On the other hand, the first-principles approach eases the understanding of symptom estimates for clinicians. We have demonstrated that the selected features of speech, gait and finger tapping were able to discriminate between symptom severity levels, as well as, between healthy controls and PD patients with high classification rates. The findings support suitability of these methods to be used as decision support tools in the context of PD assessment.

Neuronal Correlates of Perception, Imagery, and Memory for Familiar Tunes

We used fMRI to investigate the neuronal correlates of encoding and recognizing heard and imagined melodies. Ten participants were shown lyrics of familiar verbal tunes; they either heard the tune along with the lyrics, or they had to imagine it. In a subsequent surprise recognition test, they had to identify the titles of tunes that they had heard or imagined earlier. The functional data showed substantial overlap during melody perception and imagery, including secondary auditory areas. During imagery compared with perception, an extended network including pFC, SMA, intraparietal sulcus, and cerebellum showed increased activity, in line with the increased processing demands of imagery. Functional connectivity of anterior right temporal cortex with frontal areas was increased during imagery compared with perception, indicating that these areas form an imagery-related network. Activity in right superior temporal gyrus and pFC was correlated with the subjective rating of imagery vividness. Similar to the encoding phase, the recognition task recruited overlapping areas, including inferior frontal cortex associated with memory retrieval, as well as left middle temporal gyrus. The results present new evidence for the cortical network underlying goal-directed auditory imagery, with a prominent role of the right pFC both for the subjective impression of imagery vividness and for on-line mental monitoring of imagery-related activity in auditory areas.

Anxiety trait modulates psychophysiological reactions, but not habituation processes related to affective auditory stimuli

BACKGROUND: It is well known that there are specific peripheral activation patterns associated with the emotional valence of sounds. However, it is unclear how these effects adapt over time. The personality traits influencing these processes are also not clear. Anxiety disorders influence the autonomic activation related to emotional processing. However, personality anxiety traits have never been studied in the context of affective auditory stimuli. METHODS: Heart rate, skin conductance, zygomatic muscle activity and subjective rating of emotional valence and arousal were recorded in healthy subjects during the presentation of pleasant, unpleasant, and neutral sounds. Recordings were repeated 1 week later to examine possible time-dependent changes related to habituation and sensitization processes. RESULTS AND CONCLUSION: There was not a generalized habituation or sensitization process related to the repeated presentation of affective sounds, but rather, specific adaptation processes for each physiological measure. These observations are consistent with previous studies performed with affective pictures and simple tones. Thus, the measures of skin conductance activity showed the strongest changes over time, including habituation during the first presentation session and sensitization at the end of the second presentation session, whereas the facial electromyographic activity habituated only for the neutral stimuli and the heart rate did not habituate at all. Finally, we showed that the measure of personality trait anxiety influenced the orienting reaction to affective sounds, but not the adaptation processes related to the repeated presentation of these sounds.

Gait analysis in normal and spinal contused mice using the TreadScan system

Advances in spinal cord injury (SCI) research are dependent on quality animal models, which in turn rely on sensitive outcome measures able to detect functional differences in animals following injury. To date, most measurements of dysfunction following SCI rely either on the subjective rating of observers or the slow throughput of manual gait assessment. The present study compares the gait of normal and contusion-injured mice using the TreadScan system. TreadScan utilizes a transparent treadmill belt and a high-speed camera to capture the footprints of animals and automatically analyze gait characteristics. Adult female C57Bl/6 mice were introduced to the treadmill prior to receiving either a standardized mild, moderate, or sham contusion spinal cord injury. TreadScan gait analyses were performed weekly for 10 weeks and compared with scores on the Basso Mouse Scale (BMS). Results indicate that this software successfully differentiates sham animals from injured animals on a number of gait characteristics, including hindlimb swing time, stride length, toe spread, and track width. Differences were found between mild and moderate contusion injuries, indicating a high degree of sensitivity within the system. Rear track width, a measure of the animal's hindlimb base of support, correlated strongly both with spared white matter percentage and with terminal BMS. TreadScan allows for an objective and rapid behavioral assessment of locomotor function following mild-moderate contusive SCI, where the majority of mice still exhibit hindlimb weight support and plantar paw placement during stepping.

Ecological validity of virtual reality daily living activities screening for early dementia: longitudinal study

Background: Dementia is a multifaceted disorder that impairs cognitive functions, such as memory, language, and executive functions necessary to plan, organize, and prioritize tasks required for goal-directed behaviors. In most cases, individuals with dementia experience difficulties interacting with physical and social environments. The purpose of this study was to establish ecological validity and initial construct validity of a fire evacuation Virtual Reality Day-Out Task (VR-DOT) environment based on performance profiles as a screening tool for early dementia. Objective: The objectives were (1) to examine the relationships among the performances of 3 groups of participants in the VR-DOT and traditional neuropsychological tests employed to assess executive functions, and (2) to compare the performance of participants with mild Alzheimer’s-type dementia (AD) to those with amnestic single-domain mild cognitive impairment (MCI) and healthy controls in the VR-DOT and traditional neuropsychological tests used to assess executive functions. We hypothesized that the 2 cognitively impaired groups would have distinct performance profiles and show significantly impaired independent functioning in ADL compared to the healthy controls. Methods: The study population included 3 groups: 72 healthy control elderly participants, 65 amnestic MCI participants, and 68 mild AD participants. A natural user interface framework based on a fire evacuation VR-DOT environment was used for assessing physical and cognitive abilities of seniors over 3 years. VR-DOT focuses on the subtle errors and patterns in performing everyday activities and has the advantage of not depending on a subjective rating of an individual person. We further assessed functional capacity by both neuropsychological tests (including measures of attention, memory, working memory, executive functions, language, and depression). We also evaluated performance in finger tapping, grip strength, stride length, gait speed, and chair stands separately and while performing VR-DOTs in order to correlate performance in these measures with VR-DOTs because performance while navigating a virtual environment is a valid and reliable indicator of cognitive decline in elderly persons. Results: The mild AD group was more impaired than the amnestic MCI group, and both were more impaired than healthy controls. The novel VR-DOT functional index correlated strongly with standard cognitive and functional measurements, such as mini-mental state examination (MMSE; rho=0.26, P=.01) and Bristol Activities of Daily Living (ADL) scale scores (rho=0.32, P=.001). Conclusions: Functional impairment is a defining characteristic of predementia and is partly dependent on the degree of cognitive impairment. The novel virtual reality measures of functional ability seem more sensitive to functional impairment than qualitative measures in predementia, thus accurately differentiating from healthy controls. We conclude that VR-DOT is an effective tool for discriminating predementia and mild AD from controls by detecting differences in terms of errors, omissions, and perseverations while measuring ADL functional ability.

Speed control on high speed roads. Final report.

Federal Highway Administration, Traffic Systems Division, Washington, D.C.

Significant factors in truck ride quality. Volume III: data compendium. Final report.

Federal Highway Administration, Structures and Applied Mechanics Division, Washington, D.C.

Significant factors in truck ride quality. Volume I. Summary report. Final report.

Federal Highway Administration, Structures and Applied Mechanics Division, Washington, D.C.

Significant factors in truck ride quality. Volume II: comprehensive report. Final report.

Federal Highway Administration, Structures and Applied Mechanics Division, Washington, D.C.

Low-dose alcohol effects on human behavior and performance: a review of post-1984 research.

Federal Aviation Administration, Washington, D.C.

Development of specifications for passive belt systems. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Determination of long-term stability of pavement ride quality data. Final report.

Ohio Department of Transportation, Columbus

The prediction of passenger riding comfort form acceleration data. Research report.

Transportation Department, Office of University Research, Washington, D.C.

Relationship between truck ride quality and safety of operations: methodology development. Final report.

National Highway Traffic Safety Administration, Office of Driver and Pedestrian Research, Washington, D.C.