Assessment of knee alignment with varus and valgus force through the range of flexion with non-invasive navigation.

In image-free total knee arthroplasty (TKA) navigation, infra-red markers are attached to bony landmarks to provide kinematic data intra-operatively, with the aim of improving the precision of implant placement. In non-invasive navigation, infra-red markers are attached to the skin surface, with recent evidence suggesting that this can give repeatable measurements of lower limb mechanical alignment. The aim of our study was to evaluate the use of a non-invasive navigation system in the assessment of mechanical alignment with applied coronal force through the range of flexion. A previously validated non-invasive system (Physiopilot™) was tested on 23 volunteers with healthy knees. Two users performed two registrations of the software workflow on each participant's right and left knees. A force was manually applied to the end-point of varus and valgus knee laxity and the measured change in mechanical alignment was recorded. Force was applied with the knee positioned in increments of flexion from 0 to 90°. In keeping with previous studies, satisfactory values of coefficient of repeatability (CR) of 1.55 and 1.33 were found for intra-observer repeatability in measurement of supine mechanical femoro-tibial angle (MFTA) in extension, with a good inter-observer correlation of intraclass correlation coefficient (ICC) .72. However, when flexion was introduced, intra-observer and inter-observer reliability fell out with acceptable limits. Therefore, the trial did not support use of the Physiopilot™ system as a measure of MFTA when flexion is introduced. It was felt that learning-curve, soft tissue artefacts and lack of force standardisation equipment may have accounted for significant levels of error, with further studies required to address these issues.

Comparison of three methods of penile vibratory stimulation for semen retrieval in men with spinal cord injury.

STUDY DESIGN: Prospective, three-way crossover design. OBJECTIVE: Penile vibratory stimulation (PVS) is recommended as the first line of treatment for semen retrieval in anejaculatory men with spinal cord injury (SCI). This study compared ejaculatory success rates and patient preference for three methods of PVS within the same group of men with SCI. SETTING: Major medical university. METHODS: Fifteen men with SCI each received three methods of PVS. Method 1 (M1): applying one FertiCare Personal device to the dorsum or frenulum of the glans penis; Method 2 (M2): 'sandwiching' the glans penis between two FertiCare devices; Method 3 (M3): sandwiching the glans penis between the two vibrating surfaces of the Viberect-X3 device. The order of M1, M2 and M3 was varied to control for sequencing effects. Following each PVS trial, subjects rated their experience on a questionnaire with scaled responses. RESULTS: Ejaculation success rates were high for each method; however, ejaculation latency was significantly longer with M3 compared with M1 or M2. In survey questions about patient preference, there were no significant differences between M1 and M2. In contrast, M3 was rated lower than M1 and M2 in patient preference. Semen collection may be more difficult with the Viberect device. CONCLUSIONS: On the basis of these findings, we recommend attempting PVS with one FertiCare device. If that fails, use two FertiCare devices. Although the Viberect-X3 was preferred less by patients, it had similar efficacy as the Ferticare vibrator(s) and may be suitable for home use by some patients.

Assessment of Mechanical Pain Thresholds in the Orofacial Region: A Comparison Between Pinprick Stimulators and Electronic Von Frey Device.

AIMS: To compare mechanical pain thresholds (MPTs) in the orofacial region assessed with two different approaches: with an electronic von Frey (EvF) device and with custom-made weighted pinprick stimulators. The test-retest reliability, variability of MPTs, and time duration of each test were also compared, as well as the ability of each test to create stimulus-response (S-R) curves. METHODS: A total of 16 healthy volunteers participated. The MPT and S-R curve measurements were done with the two different techniques at three sites: on the skin of the right cheek (face), on the buccal gingival mucosa of the right upper premolar region (gingiva), and on the tip of the tongue (tongue). The same protocol was repeated 1 to 2 weeks later to determine test-retest reliability. RESULTS: The MPT measurements with the EvF device were significantly faster (74.4 ± 20.8 seconds) than those with the pinprick stimulators (196.1 ± 33.0 seconds; P < .001). The absolute MPT values obtained with the EvF device were significantly higher than the values obtained with the pinprick stimulators at all test sites (P < .001). MPTs assessed with the EvF device showed higher reliability (intraclass correlation coefficient [ICC] = 0.77-0.94) than MPTs assessed with the pinprick stimulators (ICC = 0.57-0.84; P = .041). The reliability of the S-R curves was excellent for both methods with no significant differences between the methods (P = .403). CONCLUSION: This study indicates that MPTs tested in the orofacial region with the EvF device were significantly higher than MPTs tested with the pinprick stimulators. However, the EvF device can be used with higher reliability and less time consumption for assessment of MPTs in the orofacial region than the pinprick stimulator technique, and also allows comparable construction of S-R curves.

Assessment of Haptic Interaction for Home-Based Physical Tele-Therapy using Wearable Devices and Depth Sensors.

In this paper a prototype system is presented for home-based physical tele-therapy using a wearable device for haptic feedback. The haptic feedback is generated as a sequence of vibratory cues from 8 vibrator motors equally spaced along an elastic wearable band. The motors guide the patients' movement as they perform a prescribed exercise routine in a way that replaces the physical therapists' haptic guidance in an unsupervised or remotely supervised home-based therapy session. A pilot study of 25 human subjects was performed that focused on: a) testing the capability of the system to guide the users in arbitrary motion paths in the space and b) comparing the motion of the users during typical physical therapy exercises with and without haptic-based guidance. The results demonstrate the efficacy of the proposed system.

Reliability and Convergent Validity of the Algometer for Vestibular Pain Assessment in Women with Provoked Vestibulodynia.

OBJECTIVE: Women with provoked vestibulodynia (PVD) suffer pain at the entry of the vagina elicited by pressure as during vaginal penetration. To quantify vestibular pain, we developed a new instrument, an algometer. The aim of this study was to investigate the test-retest reliability of the algometer and evaluate its convergent validity for vestibular pain assessment in women with PVD. METHODS: Twenty-six women with PVD participated in the study. Vestibular pain was assessed with the new algometer and the already known vulvalgesiometer during two different sessions 2 to 4 weeks apart. At each session, the pressure pain threshold (PPT) and pressure pain tolerance (PPTol) were measured twice at the 3, 6, and 9 o'clock sites of the vestibule in random order. The test-retest reliability (intra- and inter-session) of the algometer was calculated using the intraclass correlation coefficient (ICC) and standard error of measurement (SEM). Its convergent validity was evaluated by the correlation coefficients between PPTs and PPTols measured by the algometer and those measured with the vulvalgesiometer. RESULTS: Intra-session reliability at all three sites for PPTs and PPTols in both sessions was excellent (ICC = 0.859 to 0.988, P ≤ 0.002). Inter-session reliability was good to excellent (ICC = 0.683 to 0.922, SEM = 15.06 to 47.04 g, P ≤ 0.001). Significant correlations were found between the two tools for all sites for PPTs (r = 0.500 to 0.614, P ≤ 0.009) and PPTols (r = 0.809 to 0.842, P < 0.001). DISCUSSION: Findings showed that the algometer is a reliable and valid instrument for measuring PPTs and PPTols in the vestibular area in women with PVD. This technology is promising for pinpointing treatment mechanisms and efficacy.

An extension of olfactometry methods: An expandable, fully automated, mobile, MRI-compatible olfactometer.

BACKGROUND: fMRI experiments on olfaction offer new insights into the complex, but in contrast to other sensory systems, less studied cognition of odors. To perform these experiments is still a challenge. NEW METHOD: To address the challenge posed by MR settings, an olfactometer design is presented including specific improvements to the limited number of already existing olfactometers. Innovative features such as pneumatically controlled pinch valves, useable in the scanner and providing exact stimulus timing as well as a 3D-printed nasal mask inlet for common sleep laboratory masks that can be used for lateral divided stimulus presentation are introduced. To ensure a fully automated and mobile system, the use of a flexible and easily-adapted Matlab-Code and a portable adaptable container system are presented. RESULTS: The functional efficiency of these features are proven by results of an fMRI study as well as testing temporal resolution and concentration stability with a mass spectrometer. COMPARISON WITH EXISTING METHODS: The 24-channel olfactometer design presented here provides an inexpensive alternative to the currently available olfactometers including the achievement of fast onset times, lateral divided stimulus presentation and high flexibility and adaptability to different scientific questions. CONCLUSION: The olfactometer design presented in this paper can be seen as a realistic and feasible solution to overcome the challenges of presenting olfactory stimuli within the MR setting.

Mechanically evoked cortical potentials: A physiological approach to assessment of anorectal sensory pathways.

BACKGROUND: Normal defaecation involves activation of anorectal mechanoreceptors responsive to pressure and stretch. The aim of this study was to develop selective anal and rectal mucosal light-touch stimulation suitable for measurement of cortical evoked potentials (EPs) in order to explore the sensory arm of these pathways. NEW METHOD: A novel device was manufactured to deliver selective rectal and/or anal light-touch stimulation using a shielded inter-dental brush mounted on a rotating stepper motor (1Hz, 1ms, 15° rotation). Resultant somatosensory EPs recorded with a 32-channel cortical multi-electrode array were compared to those elicited by electrical anorectal stimulation (2mm anal plug electrode [1Hz, 1ms, 10V]). RESULTS: Eighteen anaesthetized female Wistar rats (body mass 180-250g) were studied. Electrical and mechanical stimulation provoked similar maximal response amplitudes (electrical anorectal 39.0µV[SEM 5.5], mechanical anal 42.2µV[8.1], mechanical rectal 45.8µV[9.0]). Response latency was longer following mechanical stimulation (electrical anorectal 8.8ms[0.5], mechanical anal 16.4ms[1.1], mechanical rectal 18.3ms[2.5]). The extent of activated sensory cortex was smaller for mechanical stimulation. Sensory inferior rectal nerve activity was greater during anal compared to rectal mechanical in a subgroup of 4 rats. Evoked potentials were reproducible over 40min in a subgroup of 9 rats. COMPARISON WITH EXISTING METHODS: Cortical EPs are typically recorded in response to non-physiological electrical stimuli. The use of a mechanical stimulus may provide a more localized physiological method of assessment. CONCLUSIONS: To the authors' knowledge these are the first selective brush-elicited anal and rectal EPs recorded in animals and provide a physiological approach to testing of anorectal afferent pathways.

Scheimpflug camera in the quantitative assessment of reproducibility of high-speed corneal deformation during intraocular pressure measurement.

The paper presents an original analysis method of corneal deformation images from the ultra-high-speed Scheimpflug camera (Corvis ST tonometer). Particular attention was paid to deformation frequencies exceeding 100 Hz and their reproducibility in healthy subjects examined repeatedly. A total of 4200 images with a resolution of 200 × 576 pixels were recorded. The data derived from 3 consecutive measurements from 10 volunteers with normal corneas. A new image analysis algorithm, written in Matlab with the use of the Image Processing package, adaptive image filtering, morphological analysis methods and fast Fourier transform, was proposed. The following results were obtained: (1) reproducibility of the eyeball reaction in healthy subjects with precision of 10%, (2) corneal vibrations with a frequency of 369 ± 65 Hz (3) and amplitude of 7.86 ± 1.28 µm, (4) the phase shift within two parts of the cornea of the same subject of about 150°. The result of image sequence analysis for one subject and deformations with a corneal frequency response above 100 Hz.

Validation of a low-cost EEG device for mood induction studies.

New electroencephalography (EEG) devices, more portable and cheaper, are appearing on the market. Studying the reliability of these EEG devices for emotional studies would be interesting, as these devices could be more economical and compatible with Virtual Reality (VR) settings. Therefore, the aim in this work was to validate a low-cost EEG device (Emotiv Epoc) to monitor brain activity during a positive emotional induction procedure. Emotional pictures (IAPS) were used to induce a positive mood in sixteen participants. Changes in the brain activity of subjects were compared between positive induction and neutral conditions. Obtained results were in accordance with previous scientific literature regarding frontal EEG asymmetry, which supports the possibility of using this low-cost EEG device in future mood induction studies combined with VR.

Assessment of pain response in capsaicin-induced dynamic mechanical allodynia using a novel and fully automated brushing device.

BACKGROUND: Dynamic mechanical allodynia is traditionally induced by manual brushing of the skin. Brushing force and speed have been shown to influence the intensity of brush-evoked pain. There are still limited data available with respect to the optimal stroke number, length, force, angle and speed. Therefore, an automated brushing device (ABD) was developed, for which brushing angle and speed could be controlled to enable quantitative assessment of dynamic mechanical allodynia. OBJECTIVES: To compare the ABD with manual brushing using capsaicin-induced allodynia, and to investigate the role of stroke angle and speed on pain intensity. METHODS: Experimental dynamic mechanical allodynia was induced by an intradermal injection of capsaicin (100 µg) into the volar forearm of 12 healthy, male volunteers. Dynamic mechanical allodynia was rated on a 10 cm visual analogue scale (VAS) after each set of strokes at angles of 30°, 60° and 90° with speeds of 17 mm/s, 21 mm/s and 25 mm/s for each angle. A two-way ANOVA with repeated measures was performed to assess the influence of brushing parameters. To evaluate test-retest reliability, Bland-Altman 95% limits of agreement, including a coefficient of repeatability and an intraclass correlation coefficient (ICC), were determined. RESULTS: The angle and speed exhibited a significant impact on pain intensity (P<0.001 and P<0.015, respectively). Post hoc analysis showed that the highest pain intensity was recorded with an angle of 30° regardless of brushing speed. The ABD demonstrated superior test-retest reliability (coefficient of repeatability = 1.9 VAS; ICC=0.91) compared with manual brushing (coefficient of repeatability = 2.8 VAS; ICC=0.80; P<0.05). The most reliable combination of parameters (coefficient of repeatability = 1.3 VAS; ICC=0.97) was an angle of 60° and a speed of 21 mm/s. CONCLUSIONS: A controlled, automatic brushing method can be used for quantitative investigations of allodynic reactions, and is more reliable for quantitative assessment of dynamic mechanical allodynia compared with traditional manual brushing.

Standardising the clinical assessment of coronal knee laxity.

Clinical laxity tests are used for assessing knee ligament injuries and for soft tissue balancing in total knee arthroplasty. This study reports the development and validation of a quantitative technique of assessing collateral knee laxity through accurate measurement of potential variables during routine clinical examination. The hypothesis was that standardisation of a clinical stress test would result in a repeatable range of laxity measurements. Non-invasive infrared tracking technology with kinematic registration of joint centres gave real-time measurement of both coronal and sagittal mechanical tibiofemoral alignment Knee flexion, moment arm and magnitude of the applied force were all measured and standardised. Three clinicians then performed six knee laxity examinations on a single volunteer using a target moment of 18 Nm. Standardised laxity measurements had small standard deviations (within 1. 1 degree) for each clinician and similar mean values between clinicians, with the valgus laxity assessment (mean of 3 degrees) being slightly more consistent than varus (means of 4 degrees or 5 degrees). The manual technique of coronal knee laxity assessment was successfully quantified and standardised, leading to a narrow range of measurements (within the accuracy of the measurement system). Minimising the subjective variables of clinical examination could improve current knowledge of soft tissue knee behaviour.

[Tribological assessment of articular cartilage. A system for the analysis of the friction coefficient of cartilage, regenerates and tissue engineering constructs; initial results]. / Tribologische Messungen am Gelenkknorpel. Ein Prüfstand zur Messung der Reibungszahlen von Knorpel gegen Knorpel, Regeneraten und TE-Konstrukten und erste Ergebnisse.

Values for the friction coefficient of articular cartilage are given in ranges of percentage and lower and are calculated as a quotient of the friction force and the perpendicular loading force acting on it. Thus, a sophisticated system has to be provided for analysing the friction coefficient under different conditions in particular when cartilage should be coupled as friction partner. It is possible to deep-freeze articular cartilage before measuring the friction coefficient as the procedure has no influence on the results. The presented tribological system was able to distinguish between altered and native cartilage. Furthermore, tissue engineered constructs for cartilage repair were differentiated from native cartilage probes by their friction coefficient. In conclusion a tribological equipment is presented to analyze the friction coefficient of articular cartilage, in vivo generated cartilage regenerates and in vitro tissue engineered constructs regarding their biomechanical properties for quality assessment.

The use of the pessary test in preoperative assessment of women with severe genital prolapse.

OBJECTIVE: To investigate whether a preoperative pessary test could be used to identify patients with occult stress incontinence and if simultaneous anti-incontinence surgery with a midurethral sling could prevent postoperative incontinence. STUDY DESIGN: Eighty-two patients with a positive pessary test and severe genital prolapse participated in the study: 43 patients underwent prolapse surgery and transobturator tension-free vaginal tape (TVT-O) insertion and 39 patients underwent prolapse surgery only. RESULTS: The objective cure rate for TVT-O and prolapse surgery was 90.7% at three months follow up and 88.4% at two years follow up. The objective cure rate for prolapse surgery only was 74.4% at three months and 58.9% at two years follow up. CONCLUSION: The pessary test can be used preoperatively in patients with significant genitourinary prolapse to identify those with occult stress urinary incontinence. The TVT-O procedure in this context could be a useful optional procedure as it appears to be very effective and safe in patients with occult stress incontinence.

Laryngeal sensory testing in the assessment of patients with laryngopharyngeal reflux.

Laryngopharyngeal reflux is commonly encountered in the ENT out-patient setting. It leads to impaired sensory capacity of the laryngeal mucosa. The sensory integrity of the laryngopharynx can be evaluated through endoscopic administration of pulsed air, which stimulates the laryngeal adductor reflex. The pressure of air needed to elicit this reflex indicates the degree of sensory impairment. Such laryngeal sensory testing gives a quantifiable means of assessment in patients with laryngopharyngeal reflux, and can be used to measure the response to treatment. Laryngeal sensory testing is safe and well tolerated by patients.

Development of a mechanical stimulator and force measurement system for the assessment of nociceptive thresholds in pigs.

A mechanical stimulator and force measurement system was developed to quantify withdrawal thresholds to noxious mechanical stimulation of the foot in young pigs. The device and associated PC software have design and control features not previously used in other mechanical stimulators. The device, capable of delivering stimulus rates between 2 and 17 mm/s, maximum force 27 N, was validated in a cross-over study on 8 juvenile pigs (6-8 weeks of age) to check the repeatability and reliability of force threshold measurement and assess its ability to measure changes in force threshold following an inflammatory challenge. Threshold force measurements were obtained over several time periods before and after the pigs received a 0.25 ml subcutaneous injection of 3% carrageenan in 0.01 M phosphate buffered saline (PBS) or PBS in the hind foot. Consistent withdrawal thresholds were measured in injected (ipsilateral) and contralateral feet, 24 h and 30 min prior to injection (mean 8.4; 95% CI 7.1-9.7 N). Carrageenan injection, but not PBS injection, induced a significant decrease in withdrawal thresholds 90 min after injection (4.6+/-0.9 N) which remained reduced for 6h after injection. The testing system provided reliable and reproducible measurements of foot withdrawal thresholds to noxious mechanical force in young pigs (weight range 32-39 kg), and was capable of detecting and monitoring changes in threshold sensitivity following the induction of acute local inflammation in the foot. The system is suitable for studying nociceptive mechanisms in pigs.

Hybrid III ATD in inverted impacts: influence of impact angle on neck injury risk assessment.

The purpose of this paper is to present a protocol of inverted drop-tests using a 50th percentile Hybrid III Anthropomorphic Test Device (ATD) and investigate the influence of angle and velocity at impact on neck injury risk assessment. The tests were based on existing cadaveric experimental protocols for inverted seated positions. In this study selected ATD impact orientations were also assessed in both the sagittal and coronal planes. Twenty-six tests were performed at impact velocities from 1.4 to 3.1 m s(-1). The drop tests confirmed previously described behavior of the ATD in axial loading of its head/neck/thorax complex. They also showed a significant influence of the initial impact angle on neck injury criteria currently used by researchers in rollover crashworthiness tests. At 1.4 m s(-1), the peak upper neck axial force of 4350 N was reduced by an average 1760 +/- 80 N for configurations with 30 degrees initial impact angle in any plane, compared to a reference inverted vertical configuration. The N(ij) was also significantly influenced. For a given impact velocity, an out-of-both-planes initial configuration resulted in the highest combined outputs. Based on these results, similar dynamic conditions (intrusion velocity, impact duration) may result in significantly different loadings of the Hybrid III neck.

An MRI-compatible foot-loading device for assessment of internal tissue deformation.

It is well known that mechanical forces acting within the soft tissues of the foot can contribute to the formation of neuropathic ulcers in people with diabetes. Presently, only surface measurements of plantar pressure are used clinically to estimate risk status due to mechanical loading. It is currently not known how surface measurements relate to the three-dimensional (3-D) internal stress/strain state of the foot. This article describes the development of a foot-loading device that allows for the direct observation of the internal deformation of foot tissues under known forces. Ground reaction forces and plantar pressure distributions during normal walking were measured in ten healthy young adults. One instant in the gait cycle, when pressure under the metatarsal heads reached a peak, was extracted for simulation in an MR imager. T1-weighted 3-D gradient echo MRI sets were collected as the simulated walking ground reaction force was incrementally applied to the foot by the novel foot-loading device. The sub-metatarsal head soft-tissue thickness decreased rapidly at first and then reached a plateau. Peak plantar pressure measurements collected within the loading device (161+/-75kPa) were lower in magnitude and less focal than pressures measured during walking (492+/-91kPa). This finding implies that although the device successfully applied full peak walking ground reaction forces to the foot, they were not distributed in the same manner as during walking. Although not representative of gait, the data collected from this in vivo mechanical test are suitable for determination of foot tissue material properties or, when combined with finite element modeling, to examine the relationship between surface loading and internal stress.

The utility of the AusEd driving simulator in the clinical assessment of driver fatigue.

Several driving simulators have been developed which range in complexity from PC based driving tasks to advanced "real world" simulators. The AusEd driving simulator is a PC based task, which was designed to be conducive to and test for driver fatigue. This paper describes the AusEd driving simulator in detail, including the technical requirements, hardware, screen and file outputs, and analysis software. Some aspects of the test are standardized, while others can be modified to suit the experimental situation. The AusEd driving simulator is sensitive to performance decrement from driver fatigue in the laboratory setting, potentially making it useful as a laboratory or office based test for driver fatigue risk management. However, more research is still needed to correlate laboratory based simulator performance with real world driving performance and outcomes.

Newly-developed measuring device for the quantitative assessment of thermal and pain thresholds of peripheral nerves.

Measuring devices for the quantitative assessment of thermal and pain thresholds are either simple and only suited for inexact tests or accurate and objective but expensive. The aim was there for to develop a cost effective device to enable a short and practical test of neurosensibility under clinical conditions. The result of this development is a new thermosensibility-measuring device (TSM) consisting of the measuring unit itself and a thermal probe. The data are registered and analysed through direct data transfer to a connected PC. Investigations carried out with this device revealed the construction to be efficient and easy to handle under clinical conditions. The TSM provides the examiner with the opportunity to monitor the neurosensory function of peripheral nerves in a reproducible way.

Recent advances in operant conditioning technology: a versatile and affordable computerized touchscreen system.

We report the construction of a new operant chamber that incorporates modern computer, touchscreen, and display technologies. An LCD display was housed in the front wall of a lightweight Plexiglas chamber. An Apple eMac computer was used to present visual stimuli on the monitor and to control other chamber events. Responses to the stimuli were recorded using a transparent resistive-type touchscreen that overlaid the monitor. The resulting system is simple and inexpensive to construct but powerful and flexible enough to explore a broad range of issues in animal learning and behavior.