Accuracy of biplane videoradiography for quantifying dynamic wrist kinematics

Accurately assessing the dynamic kinematics of the skeletal wrist could advance our understanding of the normal and pathological wrist. Biplane videoradiography (BVR) has allowed investigators to study dynamic activities in the knee, hip, and shoulder joint; however, currently, BVR has not been utilized for the wrist joint because of the challenges associated with imaging multiple overlapping bones. Therefore, our aim was to develop a BVR procedure and to quantify its accuracy for evaluation of wrist kinematics. BVR was performed on six cadaveric forearms for one neutral static and six dynamic tasks, including flexion-extension, radial-ulnar deviation, circumduction, pronation, supination, and hammering. Optical motion capture (OMC) served as the gold standard for assessing accuracy. We propose a feedforward tracking methodology, which uses a combined model of metacarpals (second and third) for initialization of the third metacarpal (MC3). BVR-calculated kinematic parameters were found to be consistent with the OMC-calculated parameters, and the BVR/OMC agreement had submillimeter and sub-degree biases in tracking individual bones as well as the overall joint’s rotation and translation. All dynamic tasks (except pronation task) showed a limit of agreement within 1.5° for overall rotation, and within 1.3 mm for overall translations. Pronation task had a 2.1° and 1.4 mm limit of agreement for rotation and translation measurement. The poorest precision was achieved in calculating the pronation-supination angle, and radial-ulnar and volar-dorsal translational components, although they were sub-degree and submillimeter. The methodology described herein may assist those interested in examining the complexities of skeletal wrist function during dynamic tasks.     

Feasibility of using a video-based motion analysis system for measuring thumb kinematics

While several different methods have been used to measure hand kinematics, fluoroscopy is generally considered to be the most accurate. Recently, video-based motion analysis has been developed for the measurement of joint kinematics. This method is versatile, easy to use, and can measure motions dynamically. Surface markers are most commonly used in the video-based motion systems. However, whether the surface markers placed on the thumb accurately represent the true kinematics of the underlying bony segment is questionable.In this study, the feasibility of surface markers to represent thumb kinematics was investigated by fluoroscopy. Both the positions of surface markers and bony landmarks were simultaneous recorded and then digitized. The Ra(2) values comparing the angular changes of the thumb interphalangeal, metacarpal and carpometacarpal joints derived using the surface markers or bony landmarks were 0.9986, 0.9730 and 0.9186 in the flexion/extension plane respectively, 0.8837, 0.9697 and 0.8775 in the abduction/adduction plane; and 0.9884, 0.9643 and 0.9431 in the opposition plane. The ranges, mean and standard deviation of the absolute differences between calculated angles of different marker sets were also compared. These data revealed that the similarities of the two different marker techniques throughout the motion cycle were high. The differences between the two methods were also within clinically allowable range of +/-5 degrees. It is concluded that the application of the video-based motion analysis system with surface markers to thumb kinematics is warranted.     

Validation of imaging-based quantification of glenohumeral joint kinematics using an unmodified clinical biplane fluoroscopy system

Model-based tracking, using CT and biplane fluoroscopy, allows highly accurate quantification of glenohumeral motion and changes in the subacromial space. Previous investigators have used custom-built biplane fluoroscopes designed specifically for kinematic applications, which are available at few institutions and require FDA approval prior to clinical use. The aim of this study was to demonstrate the utility of an off-the-shelf clinical biplane fluoroscope for kinematic applications by validating model-based tracking for measurement of glenohumeral motion using an unmodified clinical system. Biplane images of each shoulder of a cadaver torso were acquired at various joint positions and during simulated movements along anatomical planes of motion. The pose of each humerus and scapula was determined using model-based tracking and compared to a bead-based gold standard. Error due to a temporal-offset between corresponding biplane images, characteristic of clinical biplane systems, was determined by comparison of measured and known relative position of 2 bead clusters of a phantom that was imaged while moved throughout the fluoroscopy image volume. Model-based tracking had global kinematic mean absolute errors of 0.27 mm and 0.29° (static), and 0.22–0.32 mm and 0.12–0.45° (dynamic). Glenohumeral mean absolute errors were 0.39 mm and 0.45° (static), and 0.36–0.42 mm and 0.41–0.48° (dynamic). The temporal-offset was predicted to add errors of 0.06–0.85 mm and 0.05–0.28° for cadaveric trials for the speeds examined. For defined speeds, sub-millimeter and sub-degree kinematic accuracy and precision were achieved using an unmodified clinical biplane fluoroscope for quantification of glenohumeral motion.     

Evaluation of an electromagnetic position tracking device for measuring in vivo, dynamic joint kinematics

An electromagnetic position tracking device was evaluated to determine its static and dynamic accuracy and reliability for applications related to measuring in vivo joint kinematics. The device detected the position and orientation of small coiled sensors, maintained in an electromagnetic field. System output was measured against known translations or rotations throughout the measurement volume. Average translational errors during static testing were 0.1 +/- 0.04, 0.2 +/- 0.17, and 0.8 +/- 0.81 mm (mean+/-SD) for sensors 50, 300, and 550 mm away from the field generator, respectively. Average rotational errors were 0.4 +/- 0.31 degrees, 0.4 +/- 0.21 degrees, and 0.9 +/- 0.85 degrees (mean +/- SD) for sensors located at the same distances. Since we intended to use this system in an animal walking on a treadmill, we incrementally moved the sensors under various treadmill conditions. The effects of treadmill operation on translational accuracy were found to be negligible. The effects of dynamic motions on sensor-to-sensor distance were also assessed for future data collection in the animal. Sensor-to-sensor distance showed standard deviations of 2.6 mm and a range of 13 mm for the highest frequency tested (0.23 Hz). We conclude that this system is useful for static or slow dynamic motions, but is of limited use for obtaining gait kinematics at higher speeds.     

Automatic registration of MRI-based joint models to high-speed biplanar radiographs for precise quantification of in vivo anterior cruciate ligament deformation during gait

Understanding in vivo joint mechanics during dynamic activity is crucial for revealing mechanisms of injury and disease development. To this end, laboratories have utilized computed tomography (CT) to create 3-dimensional (3D) models of bone, which are then registered to high-speed biplanar radiographic data captured during movement in order to measure in vivo joint kinematics. In the present study, we describe a system for measuring dynamic joint mechanics using 3D surface models of the joint created from magnetic resonance imaging (MRI) registered to high-speed biplanar radiographs using a novel automatic registration algorithm. The use of MRI allows for modeling of both bony and soft tissue structures. Specifically, the attachment site footprints of the anterior cruciate ligament (ACL) on the femur and tibia can be modeled, allowing for measurement of dynamic ACL deformation. In the present study, we demonstrate the precision of this system by tracking the motion of a cadaveric porcine knee joint. We then utilize this system to quantify in vivo ACL deformation during gait in four healthy volunteers.     

A new method for motion capture of the scapula using an optoelectronic tracking device: a feasibility study

Optoelectronic tracking systems are rarely used in 3D studies examining shoulder movements including the scapula. Among the reasons is the important slippage of skin markers with respect to scapula. Methods using electromagnetic tracking devices are validated and frequently applied. Thus, the aim of this study was to develop a new method for in vivo optoelectronic scapular capture dealing with the accepted accuracy issues of validated methods.

Eleven arm positions in three anatomical planes were examined using five subjects in static mode. The method was based on local optimisation, and recalculation procedures were made using a set of five scapular surface markers.

The scapular rotations derived from the recalculation-based method yielded RMS errors comparable with the frequently used electromagnetic scapular methods (RMS up to 12.6° for 150° arm elevation). The results indicate that the present method can be used under careful considerations for 3D kinematical studies examining different shoulder movements.     

Validation of a new model-based tracking technique for measuring three-dimensional, in vivo glenohumeral joint kinematics

Shoulder motion is complex and significant research efforts have focused on measuring glenohumeral joint motion. Unfortunately, conventional motion measurement techniques are unable to measure glenohumeral joint kinematics during dynamic shoulder motion to clinically significant levels of accuracy. The purpose of this study was to validate the accuracy of a new model-based tracking technique for measuring three-dimensional, in vivo glenohumeral joint kinematics. We have developed a model-based tracking technique for accurately measuring in vivo joint motion from biplane radiographic images that tracks the position of bones based on their three-dimensional shape and texture. To validate this technique, we implanted tantalum beads into the humerus and scapula of both shoulders from three cadaver specimens and then recorded biplane radiographic images of the shoulder while manually moving each specimen's arm. The position of the humerus and scapula were measured using the model-based tracking system and with a previously validated dynamic radiostereometric analysis (RSA) technique. Accuracy was reported in terms of measurement bias, measurement precision, and overall dynamic accuracy by comparing the model-based tracking results to the dynamic RSA results. The model-based tracking technique produced results that were in excellent agreement with the RSA technique. Measurement bias ranged from -0.126 to 0.199 mm for the scapula and ranged from -0.022 to 0.079 mm for the humerus. Dynamic measurement precision was better than 0.130 mm for the scapula and 0.095 mm for the humerus. Overall dynamic accuracy indicated that rms errors in any one direction were less than 0.385 mm for the scapula and less than 0.374 mm for the humerus. These errors correspond to rotational inaccuracies of approximately 0.25 deg for the scapula and 0.47 deg for the humerus. This new model-based tracking approach represents a non-invasive technique for accurately measuring dynamic glenohumeral joint motion under in vivo conditions. The model-based technique achieves accuracy levels that far surpass all previously reported non-invasive techniques for measuring in vivo glenohumeral joint motion. This technique is supported by a rigorous validation study that provides a realistic simulation of in vivo conditions and we fully expect to achieve these levels of accuracy with in vivo human testing. Future research will use this technique to analyze shoulder motion under a variety of testing conditions and to investigate the effects of conservative and surgical treatment of rotator cuff tears on dynamic joint stability.     

Feasibility of using a fully immersive virtual reality system for kinematic data collection

Commercially-available Virtual Reality (VR) systems have the potential to be effective tools for simultaneous visual manipulation and kinematic data collection. Previously, these systems have been integrated with research-grade motion capture systems to provide both functionalities; however, they are yet to be used as stand-alone systems for kinematic data collection. The present study aimed to validate the HTC VIVE VR system for kinematic data collection by evaluating the accuracy of its position and orientation signals. The VIVE controller and tracker were each compared to a Polhemus Liberty magnetic tracking system sensor for angular and translational measurement error and signal drift. A sensor from each system was mounted to opposite ends of a rigid segment which was driven through fifty rotations and fifty translations. Mean angular errors for both the VIVE tracker and controller were below 0.4°. Mean translational error for both sensors was below 3 mm. Drift in the Liberty signal components was consistently lower than drift in VIVE components. However, all mean rotational drift measures were below 0.1° and all mean translational measures were below 0.35 mm. These data indicate that the HTC VIVE system has the potential to be a valid and reliable means of kinematic data collection. However, further investigation is necessary to determine the VIVE’s suitability for capturing extremely minute or high-volume movements.     

Calibration of position and angular data from a magnetic tracking device

This paper describes a method for calibrating data from a magnetic tracking device. Position and orientation data were collected in a 1. 6x0.8x1.4m(3) volume using a Polhemus Fastrak((R)) in conjunction with both a long-range and standard transmitter. Position and orientation data were calibrated using a locally linear model based on the position of the measurement. After calibration, the average position and angular errors were less than 1.8cm and 1.2 degrees up to 1.8m from the transmitter for the long-range transmitter. For the standard transmitter, even after calibration, errors increased sharply when the sensor was more than 1.2m from the transmitter. Up to that distance, post-calibration errors were less than 1.2cm and 1. 2 degrees, while up to 1.8m they were below 5cm and 4 degrees. These errors could be further reduced by noise filtering. However, use of the standard transmitter is not recommended at distance greater than 1.2m due to orientation-based effects. It was concluded that for the volume investigated, tracking devices could provide similar three-dimensional accuracy to video systems.     

Reliability of ultrasound speckle tracking with singular value decomposition for quantifying displacement in the carpal tunnel

Inhibited movement patterns of carpal tunnel structures have been found in carpal tunnel syndrome (CTS) patients. Motion analysis on ultrasound images allows us to non-invasively study the (relative) movement of carpal tunnel structures and recently a speckle tracking method using singular value decomposition (SVD) has been proposed to optimize this tracking. This study aims to assess the reliability of longitudinal speckle tracking with SVD in both healthy volunteers and patients with CTS.Images from sixteen healthy volunteers and twenty-two CTS patients were used. Ultrasound clips of the third superficial flexor tendon and surrounding subsynovial connective tissue (SSCT) were acquired during finger flexion-extension. A custom made tracking algorithm was used for the analysis. Intra-class correlation coefficients (ICCs) were calculated using a single measure, two-way random model with absolute agreement and Bland-Altman plots were added for graphical representation.ICC values varied between 0.73 and 0.95 in the control group and 0.66–0.98 in the CTS patients, with the majority of the results classified as good to excellent. Tendon tracking showed higher reliability values compared to the SSCT, but values between the control and CTS groups were comparable.Speckle tracking with SVD can reliably be used to analyze longitudinal movement of anatomical structures with different sizes and compositions within the context of the carpal tunnel in both a healthy as well as a pathological state. Based on these results, this technique also holds relevant potential for areas where ultrasound based dynamic imaging requires quantification of motion.     

Comparison of glenohumeral joint kinematics between manual wheelchair tasks and implications on the subacromial space: A biplane fluoroscopy study

Scapula and humerus motion associated with common manual wheelchair tasks is hypothesized to reduce the subacromial space. However, previous work relied on either marker-based motion capture for kinematic measures, which is prone to skin-motion artifact; or ultrasound imaging for arthrokinematic measures, which are 2D and acquired in statically-held positions. The aim of this study was to use a fluoroscopy-based approach to accurately quantify glenohumeral kinematics during manual wheelchair use, and compare tasks for a subset of parameters theorized to be associated with mechanical impingement. Biplane images of the dominant shoulder were acquired during scapular plane elevation, propulsion, sideways lean, and weight-relief raise in ten manual wheelchair users with spinal cord injury. A computed tomography scan of the shoulder was obtained, and model-based tracking was used to quantify six-degree-of-freedom glenohumeral kinematics. Axial rotation and superior/inferior and anterior/posterior humeral head positions were characterized for full activity cycles and compared between tasks. The change in the subacromial space was also determined for the period of each task defined by maximal change in the aforementioned parameters. Propulsion, sideways lean, and weight-relief raise, but not scapular plane elevation, were marked by mean internal rotation (8.1°, 10.8°, 14.7°, −49.2° respectively). On average, the humeral head was most superiorly positioned during the weight-relief raise (1.6 ± 0.9 mm), but not significantly different from the sideways lean (0.8 ± 1.1 mm) (p = 0.191), and much of the task was characterized by inferior translation. Scaption was the only task without a defined period of superior translation on average. Pairwise comparisons revealed no significant differences between tasks for anterior/posterior position (task means range: 0.1–1.7 mm), but each task exhibited defined periods of anterior translation. There was not a consistent trend across tasks between internal rotation, superior translation, and anterior translation with reductions in the subacromial space. Further research is warranted to determine the likelihood of mechanical impingement during these tasks based on the measured task kinematics and reductions in the subacromial space.     

Estimation and validation of spatio-temporal parameters for sprint running using a radio-based tracking system

Spatio-temporal parameters like step length, step frequency and ground contact time are directly related to sprinting performance. There is still a lack of knowledge, however, on how these parameters interact.Recently, various algorithms for the automatic detection of step parameters during sprint running have been presented which have been based on data from motion capture systems, video cameras, opto-electronic systems or Inertial measurement units. However, all of these methods suffer from at least one of the following shortcomings: they are (a) not applicable for more than one sprinter simultaneously, (b) only capable of capturing a small volume or (c) do not provide accurate spatial parameters. To circumvent these issues, the radio-based local position measurement system RedFIR could be used to obtain spatio-temporal information during sprinting based on lightweight transmitters attached to the athletes. To assess and optimize the accuracy of these parameters 19 100 m sprints of twelve young elite athletes (age: 16.5 ± 2.3 years) were recorded by a radio-based tracking system and a opto-electronic reference instrument. Optimal filter parameters for the step detection algorithm were obtained based on RMSE differences between estimates and reference values on an unseen test set. Attaching a transmitter above the ankle showed the best results.Bland-Altman analysis yielded 95% limits of agreement of [−14.65 cm, 15.05 cm] for step length [−0.016 s, 0.016 s] for step time and [−0.020 s, 0.028 s] for ground contact time, respectively. RMS errors smaller than 2% for step length and step time show the applicability of radio-based tracking systems to provide spatio-temporal parameters. This creates new opportunities for performance analysis that can be applied for any running discipline taking place within a stadium. Since analysis for multiple athletes is available in real-time this allows immediate feedback to coaches, athletes and media.     

Estimation of hurdle clearance parameters using a monocular human motion tracking method

This paper presents a method of monocular human motion tracking for estimation of hurdle clearance kinematic parameters. The analysis involved 10 image sequences of five hurdlers at various training levels. Recording of the sequences was carried out under simulated starting conditions of a 110 m hurdle race. The parameters were estimated using the particle swarm optimization algorithm and they are based on analysis of the images recorded with a 100 Hz camera. The proposed method does not involve using any special clothes, markers, inertial sensors, etc. As the quality criteria, the mean absolute error and mean relative error were used. The level of computed errors justifies the use of this method to estimate hurdle clearance parameters.     

Normative cervical spine kinematics of a circumduction task

Neck pain is a prevalent condition and clinical examination techniques are limited and unable to assess out-of-plane motion. Recent works investigating cervical kinematics during neck circumduction (NC), a dynamic 3D task, has shown the ability to discern those with and without neck pain. The purposes of this study were to establish 1) confidence and prediction intervals of head-to-torso kinematics during NC in a healthy cohort, 2) a baseline summative metric to quantify the duration and magnitude of deviations outside the prediction interval, and 3) the reliability of NC. Thirty-nine participants (25.6 ± 6.3 years, 19F/20M) without neck pain completed left and right NC. A two-way smoothing spline analysis of variance was utilized to determine the mean-fitted values and 90% confidence and prediction intervals for NC. A standardized effect size was calculated and aggregated across all axes (Delta RMSD aggregate), as a summative metric of motion quality. Confidence and prediction intervals were comparable for left and right NC and demonstrated excellent reliability. The average sum of the Delta RMSD aggregate was 2.76 ± 0.55 for left NC and 2.74 ± 0.63 for right NC. The results of this study demonstrate the feasibility of utilizing normative intervals of a NC task to assess head-to-torso kinematics.     

A novel method to replicate the kinematics of the carpus using a six degree-of-freedom robot

Understanding the kinematics of the carpus is essential to the understanding and treatment of wrist pathologies. However, many of the previous techniques presented are limited by non-functional motion or the interpolation of points from static images at different postures. We present a method that has the capability of replicating the kinematics of the wrist during activities of daily living using a unique mechanical testing system. To quantify the kinematics of the carpal bones, we used bone pin-mounted markers and optical motion capture methods. In this paper, we present a hammering motion as an example of an activity of daily living. However, the method can be applied to a wide variety of movements. Our method showed good accuracy (1.0–2.6°) of in vivo movement reproduction in our ex vivo model. Most carpal motion during wrist flexion–extension occurs at the radiocarpal level while in ulnar deviation the motion is more equally shared between radiocarpal and midcarpal joints, and in radial deviation the motion happens mainly at the midcarpal joint. For all rotations, there was more rotation of the midcarpal row relative to the lunate than relative to the scaphoid or triquetrum. For the functional motion studied (hammering), there was more midcarpal motion in wrist extension compared to pure wrist extension while radioulnar deviation patterns were similar to those observed in pure wrist radioulnar deviation. Finally, it was found that for the amplitudes studied the amount of carpal rotations was proportional to global wrist rotations.     

In situ comparison of A-mode ultrasound tracking system and skin-mounted markers for measuring kinematics of the lower extremity

Skin-mounted marker based motion capture systems are widely used in measuring the movement of human joints. Kinematic measurements associated with skin-mounted markers are subject to soft tissue artifacts (STA), since the markers follow skin movement, thus generating errors when used to represent motions of underlying bone segments. We present a novel ultrasound tracking system that is capable of directly measuring tibial and femoral bone surfaces during dynamic motions, and subsequently measuring six-degree-of-freedom (6-DOF) tibiofemoral kinematics. The aim of this study is to quantitatively compare the accuracy of tibiofemoral kinematics estimated by the ultrasound tracking system and by a conventional skin-mounted marker based motion capture system in a cadaveric experimental scenario. Two typical tibiofemoral joint models (spherical and hinge models) were used to derive relevant kinematic outcomes. Intra-cortical bone pins equipped with optical markers were inserted in the tibial and femoral bones to serve as a reference to provide ground truth kinematics. The ultrasound tracking system resulted in lower kinematic errors than the skin-mounted markers (the ultrasound tracking system: maximum root-mean-square (RMS) error 3.44° for rotations and 4.88 mm for translations, skin-mounted markers with the spherical joint model: 6.32° and 6.26 mm, the hinge model: 6.38° and 6.52 mm). Our proposed ultrasound tracking system has the potential of measuring direct bone kinematics, thereby mitigating the influence and propagation of STA. Consequently, this technique could be considered as an alternative method for measuring 6-DOF tibiofemoral kinematics, which may be adopted in gait analysis and clinical practice.     

Carbon coated magnetic nanoparticles for local drug delivery using magnetic implants

Bioferrofluids obtained from carbon coated iron nanoparticles are promising candidates for magnetic drug delivery. The carbon cages render the particles biocompatible, and provide a good support for drug adsorption. We propose a method in which gold plated permanent magnets are implanted directly in the affected organ, close to the tumour, by endoscopic techniques. The bioferrofluid charged with the chemotherapeutic agent is injected and the particles attracted to the magnet, then desorption of the drug takes place at the tumoral region. This method seems to be more promising, costless and effective than that based on the application of external magnetic fields. Preliminary results of drug adsorption and a preclinical experimental animal model are described.     

Determination of 3D spinal kinematics without defining a local vertebral coordinate system

In this paper a method is presented to calculate Euler's angles of rotation of a body segment during locomotion without a priori defining the location of the center of rotation, and without defining a local vertebral coordinate system. The method was applied to in vivo spinal kinematics. In this method, the orientation of each segment is identified by a set of three markers. The orientation of the axes of rotation is calculated based on the average position of the markers during one stride cycle. Some restrictions and assumptions should be made. The approach is viable only when the average orientation of the anatomical axes of rotation of each spinal segment during a stride cycle coincides with the three axes of the laboratory coordinate system. Furthermore, the rotations should be symmetrical with respect to both sides of the plane of symmetry of the spinal segment, and the subject should move parallel to one axis of the laboratory coordinate system. Since in experimental conditions these assumptions will only be met approximately, errors will be introduced in the calculated angles of rotation. The magnitude of the introduced errors was investigated in a computer simulation experiment. Since the maximal errors did not exceed 0.7° in a range of misalignments up to 10° between the two coordinate systems, the approach proved to be a valid method for the estimation of spinal kinematics.     

Improvement of design of a surgical interface using an eye tracking device

Background

Surgical interfaces are used for helping surgeons in interpretation and quantification of the patient information, and for the presentation of an integrated workflow where all available data are combined to enable optimal treatments. Human factors research provides a systematic approach to design user interfaces with safety, accuracy, satisfaction and comfort. One of the human factors research called user-centered design approach is used to develop a surgical interface for kidney tumor cryoablation. An eye tracking device is used to obtain the best configuration of the developed surgical interface.

Methods

Surgical interface for kidney tumor cryoablation has been developed considering the four phases of user-centered design approach, which are analysis, design, implementation and deployment. Possible configurations of the surgical interface, which comprise various combinations of menu-based command controls, visual display of multi-modal medical images, 2D and 3D models of the surgical environment, graphical or tabulated information, visual alerts, etc., has been developed. Experiments of a simulated cryoablation of a tumor task have been performed with surgeons to evaluate the proposed surgical interface. Fixation durations and number of fixations at informative regions of the surgical interface have been analyzed, and these data are used to modify the surgical interface.

Results

Eye movement data has shown that participants concentrated their attention on informative regions more when the number of displayed Computer Tomography (CT) images has been reduced. Additionally, the time required to complete the kidney tumor cryoablation task by the participants had been decreased with the reduced number of CT images. Furthermore, the fixation durations obtained after the revision of the surgical interface are very close to what is observed in visual search and natural scene perception studies suggesting more efficient and comfortable interaction with the surgical interface. The National Aeronautics and Space Administration Task Load Index (NASA-TLX) and Short Post-Assessment Situational Awareness (SPASA) questionnaire results have shown that overall mental workload of surgeons related with surgical interface has been low as it has been aimed, and overall situational awareness scores of surgeons have been considerably high.

Conclusions

This preliminary study highlights the improvement of a developed surgical interface using eye tracking technology to obtain the best SI configuration. The results presented here reveal that visual surgical interface design prepared according to eye movement characteristics may lead to improved usability.