A marker-less technique for measuring kinematics in the operating room.

BACKGROUND: Often in simulated settings, quantitative analysis of technical skill relies largely on specially tagged instruments or tracers on surgeons' hands. We investigated a novel, marker-less technique for evaluating technical skill during open operations and for differentiating tasks and surgeon experience level. METHODS: We recorded the operative field via in-light camera for open operations. Sixteen cases yielded 138 video clips of suturing and tying tasks ≥5 seconds in duration. Video clips were categorized based on surgeon role (attending, resident) and task subtype (suturing tasks: body wall, bowel anastomosis, complex anastomosis; tying tasks: body wall, superficial tying, deep tying). We tracked a region of interest on the hand to generate kinematic data. Nested, multilevel modeling addressed the nonindependence of clips obtained from the same surgeon. RESULTS: Interaction effects for suturing tasks were seen between role and task categories for average speed (P = .04), standard deviation of speed (P = .05), and average acceleration (P = .03). There were significant differences across task categories for standard deviation of acceleration (P = .02). Significant differences for tying tasks across task categories were observed for maximum speed (P = .02); standard deviation of speed (P = .04); and average (P = .02), maximum (P < .01), and standard deviation (P = .03) of acceleration. CONCLUSION: We demonstrated the ability to detect kinematic differences in performance using marker-less tracking during open operative cases. Suturing task evaluation was most sensitive to differences in surgeon role and task category and may represent a scalable approach for providing quantitative feedback to surgeons about technical skill.

Evaluation of Simulated Clinical Breast Exam Motion Patterns Using Marker-Less Video Tracking.

OBJECTIVE: This study investigates using marker-less video tracking to evaluate hands-on clinical skills during simulated clinical breast examinations (CBEs). BACKGROUND: There are currently no standardized and widely accepted CBE screening techniques. METHODS: Experienced physicians attending a national conference conducted simulated CBEs presenting different pathologies with distinct tumorous lesions. Single hand exam motion was recorded and analyzed using marker-less video tracking. Four kinematic measures were developed to describe temporal (time pressing and time searching) and spatial (area covered and distance explored) patterns. RESULTS: Mean differences between time pressing, area covered, and distance explored varied across the simulated lesions. Exams were objectively categorized as either sporadic, localized, thorough, or efficient for both temporal and spatial categories based on spatiotemporal characteristics. The majority of trials were temporally or spatially thorough (78% and 91%), exhibiting proportionally greater time pressing and time searching (temporally thorough) and greater area probed with greater distance explored (spatially thorough). More efficient exams exhibited proportionally more time pressing with less time searching (temporally efficient) and greater area probed with less distance explored (spatially efficient). Just two (5.9 %) of the trials exhibited both high temporal and spatial efficiency. CONCLUSIONS: Marker-less video tracking was used to discriminate different examination techniques and measure when an exam changes from general searching to specific probing. The majority of participants exhibited more thorough than efficient patterns. APPLICATION: Marker-less video kinematic tracking may be useful for quantifying clinical skills for training and assessment.

The accuracy of conventional 2D video for quantifying upper limb kinematics in repetitive motion occupational tasks.

Marker-less 2D video tracking was studied as a practical means to measure upper limb kinematics for ergonomics evaluations. Hand activity level (HAL) can be estimated from speed and duty cycle. Accuracy was measured using a cross-correlation template-matching algorithm for tracking a region of interest on the upper extremities. Ten participants performed a paced load transfer task while varying HAL (2, 4, and 5) and load (2.2 N, 8.9 N and 17.8 N). Speed and acceleration measured from 2D video were compared against ground truth measurements using 3D infrared motion capture. The median absolute difference between 2D video and 3D motion capture was 86.5 mm/s for speed, and 591 mm/s(2) for acceleration, and less than 93 mm/s for speed and 656 mm/s(2) for acceleration when camera pan and tilt were within ± 30 degrees. Single-camera 2D video had sufficient accuracy (< 100 mm/s) for evaluating HAL. Practitioner Summary: This study demonstrated that 2D video tracking had sufficient accuracy to measure HAL for ascertaining the American Conference of Government Industrial Hygienists Threshold Limit Value(®) for repetitive motion when the camera is located within ± 30 degrees off the plane of motion when compared against 3D motion capture for a simulated repetitive motion task.

A hand speed-duty cycle equation for estimating the ACGIH hand activity level rating.

An equation was developed for estimating hand activity level (HAL) directly from tracked root mean square (RMS) hand speed (S) and duty cycle (D). Table lookup, equation or marker-less video tracking can estimate HAL from motion/exertion frequency (F) and D. Since automatically estimating F is sometimes complex, HAL may be more readily assessed using S. Hands from 33 videos originally used for the HAL rating were tracked to estimate S, scaled relative to hand breadth (HB), and single-frame analysis was used to measure D. Since HBs were unknown, a Monte Carlo method was employed for iteratively estimating the regression coefficients from US Army anthropometry survey data. The equation: HAL = 10[e(-15:87+0:02D+2:25 ln S)/(1+e(-15:87+0:02D+2:25 ln S)], R(2) = 0.97, had a residual range ± 0.5 HAL. The S equation superiorly fits the Latko et al. ( 1997 ) data and predicted independently observed HAL values (Harris 2011) better (MSE = 0.16) than the F equation (MSE = 1.28).

Quantifying technical skills during open operations using video-based motion analysis.

INTRODUCTION: Objective quantification of technical operative skills in surgery remains poorly defined, although the delivery of and training in these skills is essential to the profession of surgery. Attempts to measure hand kinematics to quantify operative performance primarily have relied on electromagnetic sensors attached to the surgeon's hand or instrument. We sought to determine whether a similar motion analysis could be performed with a marker-less, video-based review, allowing for a scalable approach to performance evaluation. METHODS: We recorded six reduction mammoplasty operations-a plastic surgery procedure in which the attending and resident surgeons operate in parallel. Segments representative of surgical tasks were identified with Multimedia Video Task Analysis software. Video digital processing was used to extract and analyze the spatiotemporal characteristics of hand movement. RESULTS: Attending plastic surgeons appear to use their nondominant hand more than residents when cutting with the scalpel, suggesting more use of countertraction. While suturing, attendings were more ambidextrous, with smaller differences in movement between their dominant and nondominant hands than residents. Attendings also seem to have more conservation of movement when performing instrument tying than residents, as demonstrated by less nondominant hand displacement. These observations were consistent within procedures and between the different attending plastic surgeons evaluated in this fashion. CONCLUSION: Video motion analysis can be used to provide objective measurement of technical skills without the need for sensors or markers. Such data could be valuable in better understanding the acquisition and degradation of operative skills, providing enhanced feedback to shorten the learning curve.

Evaluation of Hands-On Clinical Exam Performance Using Marker-less Video Tracking.

This study investigates the potential of using marker-less video tracking of the hands for evaluating hands-on clinical skills. Experienced family practitioners attending a national conference were recruited and asked to conduct a breast examination on a simulator that simulates different clinical presentations. Videos were made of the clinician's hands during the exam and video processing software for tracking hand motion to quantify hand motion kinematics was used. Practitioner motion patterns indicated consistent behavior of participants across multiple pathologies. Different pathologies exhibited characteristic motion patterns in the aggregate at specific parts of an exam, indicating consistent inter-participant behavior. Marker-less video kinematic tracking therefore shows promise in discriminating between different examination procedures, clinicians, and pathologies.

Automated video exposure assessment of repetitive hand activity level for a load transfer task.

OBJECTIVE: A new method is described for automatically quantifying repetitive hand activity with the use of digital video processing. BACKGROUND: The hand activity level (HAL) is widely used for evaluating repetitive hand work. Conventional methods involving either a trained observer on- or off-site or manual off-site video analysis are often considered inaccurate, cumbersome, or impractical for routine work assessment METHOD: A cross-correlation-based template-matching algorithm was programmed to track the motion trajectory of a selected region of interest across successive video frames for a single camera to measure repetition frequency, duty cycle, and HAL. A simple, paced, load transfer task was used to simulate a repetitive industrial activity. A total of 12 participants were videoed performing the task for varying HAL conditions. The automatically predicted HAL was compared with the manually measured HAL with the use of frame-by-frame video analysis. RESULTS: Predicted frequency, duty cycle, and HAL were in concert with the manually measured HAL conditions. The linear regression slopes of the automatically predicted values with respect to the manually measured values were 0.98 (R2 = .79), 1.27 (R2 = .63), and 1.06 (R2 = .77) for frequency, duty cycle, and HAL, respectively. CONCLUSION: A proof-of-concept for automatic video-based direct exposure assessment was demonstrated. APPLICATION: The video assessment method for repetitive motion is promising for automatic, unobtrusive, and objective exposure assessment, which may offer broad availability with the use of a camera-enabled mobile device for helping evaluate, prevent, and control exposure to repetitive motions related to upper-extremity injuries in the workplace.

Increased NF-κB signalling up-regulates BACE1 expression and its therapeutic potential in Alzheimer's disease.

Elevated levels of ß-site APP cleaving enzyme 1 (BACE1) were found in the brain of some sporadic Alzheimer's disease (AD) patients; however, the underlying mechanism is unknown. BACE1 cleaves ß-amyloid precursor protein (APP) to generate amyloid ß protein (Aß), a central component of neuritic plaques in AD brains. Nuclear factor-kappa B (NF-κB) signalling plays an important role in gene regulation and is implicated in inflammation, oxidative stress and apoptosis. In this report we found that both BACE1 and NF-κB p65 levels were significantly increased in the brains of AD patients. Two functional NF-κB-binding elements were identified in the human BACE1 promoter region. We found that NF-κB p65 expression resulted in increased BACE1 promoter activity and BACE1 transcription, while disruption of NF-κB p65 decreased BACE1 gene expression in p65 knockout (RelA-knockout) cells. In addition, NF-κB p65 expression leads to up-regulated ß-secretase cleavage and Aß production, while non-steroidal anti-inflammatory drugs (NSAIDs) inhibited BACE1 transcriptional activation induced by strong NF-κB activator tumour necrosis factor-alpha (TNF-α). Taken together, our results clearly demonstrate that NF-κB signalling facilitates BACE1 gene expression and APP processing, and increased BACE1 expression mediated by NF-κB signalling in the brain could be one of the novel molecular mechanisms underlying the development of AD in some sporadic cases. Furthermore, NSAIDs could block the inflammation-induced BACE1 transcription and Aß production. Our study suggests that inhibition of NF-κB-mediated BACE1 expression may be a valuable drug target for AD therapy.

Valproic acid inhibits Abeta production, neuritic plaque formation, and behavioral deficits in Alzheimer's disease mouse models.

Neuritic plaques in the brains are one of the pathological hallmarks of Alzheimer's disease (AD). Amyloid beta-protein (Abeta), the central component of neuritic plaques, is derived from beta-amyloid precursor protein (APP) after beta- and gamma-secretase cleavage. The molecular mechanism underlying the pathogenesis of AD is not yet well defined, and there has been no effective treatment for AD. Valproic acid (VPA) is one of the most widely used anticonvulsant and mood-stabilizing agents for treating epilepsy and bipolar disorder. We found that VPA decreased Abeta production by inhibiting GSK-3beta-mediated gamma-secretase cleavage of APP both in vitro and in vivo. VPA treatment significantly reduced neuritic plaque formation and improved memory deficits in transgenic AD model mice. We also found that early application of VPA was important for alleviating memory deficits of AD model mice. Our study suggests that VPA may be beneficial in the prevention and treatment of AD.

Increased BACE1 maturation contributes to the pathogenesis of Alzheimer's disease in Down syndrome.

Almost all Down syndrome (DS) patients develop characteristic Alzheimer's disease (AD) neuropathology, including neuritic plaques and neurofibrillary tangles, after middle age. The mechanism underlying AD neuropathology in DS has been unknown. Abeta is the central component of neuritic plaques and is generated from APP by cleavage by the beta- and gamma-secretases. Here we show that beta-secretase activity is markedly elevated in DS. The ratio of mature to immature forms of BACE1 is altered in DS. DS has significantly higher levels of mature BACE1 proteins in Golgi than normal controls. Time-lapse live image analysis showed that BACE1 proteins were predominantly immobile in Golgi in DS cells, while they underwent normal trafficking in controls. Thus, overproduction of Abeta in DS is caused by abnormal BACE1 protein trafficking and maturation. Our results provide a novel molecular mechanism by which AD develops in DS and support the therapeutic potential of inhibiting BACE1 in AD and DS.