Feasibility of a kinect-based system in assessing physical function of the elderly for home-based care.

BACKGROUND: With concerns about accurate diagnosis through telehealth, the Kinect sensor offers a reliable solution for movement analysis. However, there is a lack of practical research investigating the suitability of a Kinect-based system as a functional fitness assessment tool in homecare settings. Hence, the objective of this study was to evaluate the feasibility of using a Kinect-based system to assess physical function changes in the elderly. METHODS: The study consisted of two phases. Phase one involved 35 young healthy adults, evaluating the reliability and validity of a Kinect-based fitness evaluation compared to traditional physical examination using the intraclass correlation coefficient (ICC). Phase two involved 665 elderly subjects, examining the correlation between the Kinect-based fitness evaluation and physical examination through Pearson's correlation coefficients. A Kinect sensor (Microsoft Xbox One Kinect V2) with customized software was employed to capture and compute the movement of joint centers. Both groups performed seven functional assessments simultaneously monitored by a physical therapist and the Kinect system. System usability and user satisfaction were assessed using the System Usability Scale (SUS) and Questionnaire for User Interface Satisfaction (QUIS), respectively. RESULTS: Kinect-based system showed overall moderate to excellent within-day reliability (ICC = 0.633-1.0) and between-day reliability (ICC = 0.686-1.0). The overall agreement between the two devices was highly correlated (r ≧ 0.7) for all functional assessment tests in young healthy adults. The Kinect-based system also showed a high correlation with physical examination for the functional assessments (r = 0.858-0.988) except functional reach (r = 0.484) and walking speed(r = 0.493). The users' satisfaction with the system was excellent (SUS score = 84.4 ± 18.5; QUIS score = 6.5-6.7). CONCLUSIONS: The reliability and validity of Kinect for assessing functional performance are generally favorable. Nonetheless, caution is advised when employing Kinect for tasks involving depth changes, such as functional reach and walking speed tests for their moderate validity. However, Kinect's fundamental motion detection capabilities demonstrate its potential for future applications in telerehabilitation in different healthcare settings.

Frailty Level Classification of the Community Elderly Using Microsoft Kinect-Based Skeleton Pose: A Machine Learning Approach.

Frailty is one of the most important geriatric syndromes, which can be associated with increased risk for incident disability and hospitalization. Developing a real-time classification model of elderly frailty level could be beneficial for designing a clinical predictive assessment tool. Hence, the objective of this study was to predict the elderly frailty level utilizing the machine learning approach on skeleton data acquired from a Kinect sensor. Seven hundred and eighty-seven community elderly were recruited in this study. The Kinect data were acquired from the elderly performing different functional assessment exercises including: (1) 30-s arm curl; (2) 30-s chair sit-to-stand; (3) 2-min step; and (4) gait analysis tests. The proposed methodology was successfully validated by gender classification with accuracies up to 84 percent. Regarding frailty level evaluation and prediction, the results indicated that support vector classifier (SVC) and multi-layer perceptron (MLP) are the most successful estimators in prediction of the Fried's frailty level with median accuracies up to 97.5 percent. The high level of accuracy achieved with the proposed methodology indicates that ML modeling can identify the risk of frailty in elderly individuals based on evaluating the real-time skeletal movements using the Kinect sensor.

Reweighting of the sensory inputs for postural control in patients with cervical spondylotic myelopathy after surgery.

BACKGROUND: Cervical spondylotic myelopathy (CSM) is a degenerative cervical disease in which the spinal cord is compressed. Patients with CSM experience balance disturbance because of impaired proprioception. The weighting of the sensory inputs for postural control in patients with CSM is unclear. Therefore, this study investigated the weighting of sensory systems in patients with CSM. METHOD: Twenty-four individuals with CSM (CSM group) and 24 age-matched healthy adults (healthy control group) were analyzed in this observational study. The functional outcomes (modified Japanese Orthopaedic Association Scale [mJOA], Japanese Orthopaedic Association Cervical Myelopathy Questionnaire [JOACMEQ], Nurick scale) and static balance (eyes-open and eyes-closed conditions) were assessed for individuals with CSM before surgery, 3 and 6 months after surgery. Time-domain and time-frequency-domain variables of the center of pressure (COP) were analyzed to examine the weighting of the sensory systems. RESULTS: In the CSM group, lower extremity function of mJOA and Nurick scale significantly improved 3 and 6 months after surgery. Before surgery, the COP mean velocity and total energy were significantly higher in the CSM group than in the control group for both vision conditions. Compared with the control group, the CSM group exhibited lower energy content in the moderate-frequency band (i.e., proprioception) and higher energy content in the low-frequency band (i.e., cerebellar, vestibular, and visual systems) under the eyes-open condition. The COP mean velocity of the CSM group significantly decreased 3 months after surgery. The energy content in the low-frequency band (i.e., visual and vestibular systems) of the CSM group was closed to that of the control group 6 months after surgery under the eyes-open condition. CONCLUSION: Before surgery, the patients with CSM may have had compensatory sensory weighting for postural control, with decreased weighting on proprioception and increased weighting on the other three sensory inputs. After surgery, the postural control of the patients with CSM improved, with decreased compensation for the proprioceptive system from the visual and vestibular inputs. However, the improvement remained insufficient because the patients with CSM still had lower weighting on proprioception than the healthy adults did. Therefore, patients with CSM may require balance training and posture education after surgery. TRIAL REGISTRATION: Trial Registration number: NCT03396055 Name of the registry: ClinicalTrials.gov Date of registration: January 10, 2018 - Retrospectively registered Date of enrolment of the first participant to the trial: October 19, 2015.

Effects of combat training on visuomotor performance in children aged 9 to 12 years - an eye-tracking study.

BACKGROUND: Data on visuomotor performance in combat training and the effects of combat training on visuomotor performance are limited. This study aimed to investigate the effects of a specially designed combat sports (CS) training program on the visuomotor performance levels of children. METHODS: A pre-post comparative design was implemented. A total of 26 students aged 9-12 years underwent 40-min CS training sessions twice a week for 8 weeks during their physical education classes. The CS training program was designed by a karate coach and a motor control specialist. The other 30 students continued their regular activities and were considered as a control group. Each student's eye movement was monitored using an eye tracker, whereas the motor performance was measured using a target hitting system with a program-controlled microprocessor. The measurements were taken 8 weeks before (baseline), 1 day before (pretest), and 1 week after (posttest) the designated training program. The task used for evaluating these students was hitting or tracking random illuminated targets as rapidly as possible. A two-way analysis of variance [group(2) × time(3)] with repeated measures of time was performed for statistical analysis. RESULTS: For the children who received combat training, although the eye response improvement was not significant, both the primary and secondary saccade onset latencies were significantly earlier compared to the children without combat training. Both groups of students exhibited improvement in their hit response times during the target hitting tasks. CONCLUSION: The current finding supported the notion that sports training efforts essentially enhance visuomotor function in children aged 9-12 years, and combat training facilitates an earlier secondary saccade onset.

Identification of head control deficits following anterior cervical discectomy and fusion in patients with cervical spondylotic myelopathy.

PURPOSE: To investigate the presence of head control deficits and its course of recovery after anterior cervical discectomy and fusion (ACDF) surgery in cervical spondylotic myelopathy (CSM) patients. METHODS: Thirty-seven CSM patients were assessed for their C2-C7 cervical lordosis, neck Range of Motion (ROM), repositioning accuracy, neck strength as well as surface electromyography of the neck muscle activities during slow head motions. Assessments were performed preoperatively and then at 3- and 6-month postoperatively. RESULTS: No significant difference was found for the C2-C7 cervical lordosis postoperatively at 6-month. ROM was restricted immediately after surgery but recovered over time, however, neck strength remained significantly reduced postoperatively. Reposition accuracy improved immediately after surgery but declined again at 6-month follow-up. In addition, muscle activities required to control head motions showed a continuous reduction postoperatively. CONCLUSIONS: Adequate C2-C7 cervical lordosis was maintained in the current study with improvement of slow head motion control and ROM at 6-month. However, improvement in head position sense was not maintained and neck strength showed continuous declination overtime. Assessment and monitoring of head control deficits should be routinely considered in CSM patients.

A Multimedia Child Developmental Screening Checklist: Design and Validation.

BACKGROUND: Identifying disability early in life confers long-term benefits for children. The Taipei City Child Development Screening tool, second version (Taipei II) provides checklists for 13 child age groups from 4 months to 6 years. However, the usability of a text-based screening tool largely depends on the literacy level and logical reasoning ability of the caregivers, as well as language barriers caused by increasing numbers of immigrants. OBJECTIVE: The objectives of this study were to (1) design and develop a Web-based multimedia version of the current Taipei II developmental screening tool, and (2) investigate the measurement equivalence of this multimedia version to the original paper-based version. METHODS: To develop the multimedia version of Taipei II, a team of experts created illustrations, translations, and dubbing of the original checklists. The developmental screening test was administered to a total of 390 primary caregivers of children aged between 4 months and 6 years. RESULTS: Psychometric testing revealed excellent agreement between the paper and multimedia versions of Taipei II. Good to excellent reliabilities were demonstrated for all age groups for both the cross-mode similarity (mode intraclass correlation range 0.85-0.96) and the test-retest reliability (r=.93). Regarding the usability, the mean score was 4.80 (SD 0.03), indicating that users were satisfied with their multimedia website experience. CONCLUSIONS: The multimedia tool produced essentially equivalent results to the paper-based tool. In addition, it had numerous advantages, such as it can facilitate active participation and promote early screening of target populations. CLINICALTRIAL: Clinicaltrials.gov NCT02359591; https://clinicaltrials.gov/ct2/show/NCT02359591 (Archived by WebCite at http://www.webcitation.org/6l21mmdNn).

Multi-muscle coordination during a challenging stance.

PURPOSE: This study aimed to identify the muscle synergies during standing under various sensory contexts in healthy young adults. METHODS: Sixteen healthy young adults participated in this study. The 4-min stance task was conducted under vision (eyes open or eyes closed) and proprioception (standing on ground or narrowed blocks) manipulated contexts. Electromyography (EMG) of 8 muscles around the right side of the trunk and leg were recorded and submitted to principal component analysis (PCA) to extract the muscle synergies. Two-way ANOVA with repeated measures was employed to test the effect of sensory contexts on the muscle synergies. RESULTS: PCA extracted three muscle synergies that accounted for the variance of standing EMG, including the push-back (composed of medial gastrocnemius, vastus medialis and biceps femoris), push-forward (composed of tibialis anterior and rectus femoris) and proximal mixed (composed of rectus abdominis, rector spinae, rectus femoris and biceps femoris) synergies. Block-standing increased the contribution of the push-back synergy while decreased the contribution of the push-forward synergy. In addition, contribution of the proximal mixed synergy was higher under ground-standing with eyes open than under block-standing with eyes open. CONCLUSION: Three muscle synergies were identified during standing in healthy young adults, and the synergies were affected by proprioception but not visual disturbance. The push-back and push-forward synergies showed the opposite response to proprioceptive disturbance, which may result from their antagonism role. Whether this control regime is used for elderly adults or patient populations with movement disorder needs to be further investigated.

Differential segmental motion contribution of single- and two-level anterior cervical discectomy and fusion.

PURPOSE: To determine and compare the biomechanical effects of single- and two-level anterior cervical decompression and fusion (ACDF) on the re-distribution of the segmental contribution to total cervical range of motion (ROM) in a prospective longitudinal design. METHODS: Fifty-one patients undergoing either a single- or two-level ACDF due to cervical disc disease were recruited. Functional radiographs were taken preoperatively and then at 3, 6 and 12-month follow-ups. Global ROM of C2-C7, ROM of the treated functional spinal unit (FSU) and the superior and inferior segmental ROMs were then measured. The relative contribution from the FSU and each of the adjacent segments to total cervical ROM were compared pre- and post-operatively within and between the two groups at each of the time points. RESULTS: Single-level ACDF patients demonstrated a significantly greater total cervical ROM at 6 and 12 months compared with the two-level ACDF group (p = 0.021 and 0.045, respectively). A significantly greater contribution from the FSU to the total ROM was found at 3 months in the two-level ACDF group (p = 0.016), but the greater contribution shifted to the superior adjacent segment at 6 and 12 months (p = 0.025 and 0.046). The two-level ACDF group did not demonstrate a significant difference at 3 months (p = 0.087), but a significant increase in contribution was found at 6 and 12 months (p < 0.01). CONCLUSIONS: Single-level ACDF maintains and restores a more physiological re-distribution of segmental contribution of ROM compared with two-level ACDF, which required longer time to achieve stable FSU immobilization and coupled with significantly increased superior segment contribution.

Long-term effects of therapeutic exercise on nonspecific chronic neck pain: a literature review.

[Purpose] Nonspecific neck pain is a common musculoskeletal disease. Therapeutic exercise has been shown to improve pain and disability in short-term and midterm follow-ups. This study performed a literature review of the long-term effects of therapeutic exercise on subjects with nonspecific chronic neck pain. [Subjects and Methods] The databases of the CINAHL, MEDLINE, PEDro and PubMed were used. Randomized controlled trials (RCT) published from January 2000 to January 2014 and explicitly including a one-year follow-up were identified. [Results] Only six articles were included in this review. They had scores of 5 to 8 points on the PEDro scale, and the level of evidence was grade I. The study results show that the main exercises used were cervical strengthening and endurance training exercise. Short-term exercises (10 to 12 weeks) helped to improve the body function, structure, activity and participation immediately after the intervention, but not at the long-term follow-up. On the other hand, long-term interventions (1 year) resulted in improvements in body function and structure at the 3 year follow-up. [Conclusion] The results of the six high-quality studies suggest that long-term exercise have long-term benefits for patients with nonspecific neck pain in terms of body function and structure.

Exercise training for non-operative and post-operative patient with cervical radiculopathy: a literature review.

[Purpose] Cervical radiculopathy is a clinical condition associated with pain, numbness and/or muscle weaknesses of the upper extremities due to a compression or irritation of the cervical nerve roots. It is usually managed conservatively but surgical intervention is sometimes required for those who fail to respond adequately. This study performed a literature review to determine the effects of exercise on non-operative and post-operative cervical radiculopathy patients. [Methods] The PubMed, MEDLINE, CINAHL and Scopus databases were searched to identify relevant articles published from January 1997 to May 2014, which explicitly stated that an exercise program was employed as an intervention for cervical radiculopathy. The therapeutic effectiveness and outcomes were then classified based on the International Classification of Functioning, Disability and Health (ICF) model. [Results] Eleven studies were identified and included in the final analysis. In these studies, the main forms of exercise training were specific strengthening and general stretching exercises. Levels of evidence were graded as either I or II for all studies according to the Oxford Centre for Evidence-based Medicine. The PEDro Scale score of these studies ranged from 5 to 8. [Conclusion] A review of eleven high-level evidence and high-quality studies revealed that, based on the ICF model, exercise training is beneficial for improving the body function as well as activity participation of cervical radiculopathy patients.

Joystick-controlled video console game practice for developing power wheelchairs users' indoor driving skills.

[Purpose] This study aimed to determine the effectiveness of joystick-controlled video console games in enhancing subjects' ability to control power wheelchairs. [Subjects and Methods] Twenty healthy young adults without prior experience of driving power wheelchairs were recruited. Four commercially available video games were used as training programs to practice joystick control in catching falling objects, crossing a river, tracing the route while floating on a river, and navigating through a garden maze. An indoor power wheelchair driving test, including straight lines, and right and left turns, was completed before and after the video game practice, during which electromyographic signals of the upper limbs were recorded. The paired t-test was used to compare the differences in driving performance and muscle activities before and after the intervention. [Results] Following the video game intervention, participants took significantly less time to complete the course, with less lateral deviation when turning the indoor power wheelchair. However, muscle activation in the upper limbs was not significantly affected. [Conclusion] This study demonstrates the feasibility of using joystick-controlled commercial video games to train individuals in the control of indoor power wheelchairs.

Use of motor abundance in old adults in the regulation of a narrow-based stance.

PURPOSE: The ability to maintain stable balance while standing decreases with age. The body must coordinate multiple joints using "freeze" or "free" strategy, or a combination of both to ensure balance stability. The purpose of this study was to examine age-related changes in the use of motor abundance during upright stance on a narrow base without visual input. METHODS: Uncontrolled manifold (UCM) analysis was used to decompose the movement variability of joints into goal-equivalent variability (GEV) and non-goal-equivalent variability (NGEV). The ratio between GEV and NGEV (UCM(ratio)) quantifies the joint coordination related to postural stability, and a high UCM(ratio) value indicates flexible control of joints. To perform balance tests, participants in this study (healthy young and old adults, 20 each) were asked to stand on a flat platform and on narrow wooden blocks with their eyes open and then eyes closed. RESULTS: In upright balance tests, both old and young adults maintained postural stability. GEV was greater than NGEV across all participants and conditions. However, GEV was higher in the young adults than in the old adults, whereas NGEV was higher in the old adults than in the young adults. Therefore, the old adults exhibited a lower UCM(ratio) than the young adults. CONCLUSION: The old adults were unable to exploit motor abundance and used a less flexible multi-joint coordination pattern to achieve stable balance. The UCM(ratio) value reflects the quality of postural control and can be used for assessing joint coordination in balance disorders.

Altered Co-contraction of Cervical Muscles in Young Adults with Chronic Neck Pain during Voluntary Neck Motions.

[Purpose] Muscle co-contraction is important in stabilizing the spine. The aim of this study was to compare cervical muscle co-contraction in adults with and without chronic neck pain during voluntary movements. [Subjects and Methods] Surface electromyography of three paired cervical muscles was measured in fifteen young healthy subjects and fifteen patients with chronic neck pain. The subjects performed voluntary neck movements in the sagittal and coronal plane at slow speed. The co-contraction ratio was defined as the normalized integration of the antagonistic electromyography activities divided by that of the total muscle activities. [Results] The results showed that the co-contraction ratio of patients was greater during flexion movement, lesser during extension movement, slightly greater during right lateral bending, and slightly lesser during left lateral bending compared with in the controls. [Conclusion] The results suggested that neck pain patients exhibit greater antagonistic muscle activity during flexion and dominate-side bending movements to augment spinal stability, while neuromuscular control provides relatively less protection in the opposite movements. This study helps to specify the changes of the stiffness of the cervical spine in neck pain patients and provides a useful tool and references for clinical assessment of neck disorders.

Enzymatic denaturation versus excessive fatigue loading degeneration: Effects on the time-dependent response of the intervertebral disc.

Degenerative disc disease (DDD), regardless of its phenotype and clinical grade, is widely associated with low back pain (LBP), which remains the single leading cause of disability worldwide. This work provides a quantitative methodology for comparatively investigating artificial IVD degeneration via two popular approaches: enzymatic denaturation and fatigue loading. An in-vitro animal study was used to study the time-dependent responses of forty fresh juvenile porcine thoracic IVDs in conjunction with inverse and forward finite element (FE) simulations. The IVDs were dissected from 6-month-old-juvenile pigs and equally assigned to 5 groups (intact, denatured, low-level, medium-level, high-level fatigue loading). Upon preloading, a sinusoid cyclic load (Peak-to-peak/0.1-to-0.8 MPa) was applied (0.01-10 Hz), and dynamic-mechanical-analyses (DMA) was performed. The DMA outcomes were integrated with a robust meta-model analysis to quantify the poroelastic IVD characteristics, while specimen-specific FE models were developed to study the detailed responses. The results demonstrated that enzymatic denaturation had a more significantly pronounced effect on the resistive strength and shock attenuation capabilities of the intervertebral discs. This can be attributed to the simultaneous disruption of the collagen fibers and water-proteoglycan bonds induced by trypsin digestion. Fatigue loading, on the other hand, primarily influenced the disc's resistance to deformation in a frequency-dependent pattern, where alterations were most noticeable at low loading frequencies. This study confirms the intricate interplay between the biochemical changes induced by enzymatic processes and the mechanical behavior stemming from fatigue loading, suggesting the need for a comprehensive approach to closely mimic the interrelated multifaceted processes of human disc degeneration.

Impact of osteoporosis and Cement-Augmented fusion on adjacent spinal levels Post-Fusion Surgery: Patient-Specific finite element analysis.

Cement-augmentation is a technique commonly used during posterior lumbar instrumented fusion (PLIF) to reinforce compromised osteoporotic vertebral bone, minimize the risk of loosening screws, enhance stability, and improve overall surgical outcomes. In this study, we introduce a novel segmented vertebral body regional modeling approach to investigate the effects of osteoporosis and cement-augmented lumbar fusion on disc biomechanics at spinal levels adjacent to the fused vertebrae. Using our previously validated personalized-poroelastic-osteoligamentous FE model of the spine, fusion was simulated at L4-L5, and the biomechanics of adjacent levels were studied for 30 patients (non-osteoporotic patients (N = 15), osteoporotic patients (N = 15)). PLIF models, with and without cement-augmentation, were developed and compared after an 8 h-rest period (200 N), following a 16 h-cyclic compressive loading of 500-1000 N (40 and 20 min, respectively). Movement in different directions (flexion/ extension/ lateral bending/ axial rotation) was simulated using 10Nm moment before and after cyclic loading. The material mapping algorithm was validated by comparing the results of voxel-based and parametric models. The FE cement-augmented models, subject to daily activity loading, demonstrated significant differences in disc height loss and fluid loss as compared to non-cemented models. The calculated axial stress and fiber strain values were also significantly higher for these models. This work demonstrates that although osteoporosis does not significantly alter the time-dependent characteristics of adjacent IVDs post-surgery, cement-augmentation increases the risk of adjacent segment disease (ASD) incidence. A holistic understanding of the trade-offs and long-term complex interplay between structural reinforcement modalities, including cement augmentation, and altered biomechanics warrants further investigation.

Biomechanical Investigation of Bone Screw Head Design for Extracting Stripped Screw Heads: Integration of Mechanical Tests and Finite Element Analyses.

Enhancing the design of bone screw head sockets to prevent stripping and improve the torque required for smooth unscrewing is a significant challenge in orthopedic applications. This research aims to establish a quantitative methodology by integrating mechanical testing with finite element (FE) simulations to determine a safe limitation depth for the screwdriver when engaging with the hexagonal socket, thus avoiding stripped screw heads. A FE model was developed to investigate the biomechanical responses of the screw head design. Five custom-made hexagonal sockets were manufactured, and single load torsional tests were conducted to assess the mechanical performance of the screws and drivers. The results from the mechanical tests were compared with the FE simulations, demonstrating a close agreement and confirming the model's validity. Furthermore, additional FE models were created to study the impact of manufacturing tolerances on the socket width and screwdriver width. The findings revealed that the maximum torque to failure for the four designs was lower than the margins specified in ISO 6475. Additionally, increasing the depth of the screwdriver led to higher maximum torque values. This research suggests that the technique of screw insertion, specifically the depth of the driver tool within the screw socket, holds greater importance in preventing stripped screw heads than the design and manufacturing width of the bone screw's hexagonal socket and screwdriver. This confirms the importance of screwdriver engagement inside the bone screw socket to prevent stripped screw heads and sheds light on the added value of maximum torque prediction for future design modifications.

The influence of over-distraction on biomechanical response of cervical spine post anterior interbody fusion: a comprehensive finite element study.

Introduction: Anterior cervical discectomy and fusion (ACDF) has been considered as the gold standard surgical treatment for cervical degenerative pathologies. Some surgeons tend to use larger-sized interbody cages during ACDF to restore the index intervertebral disc height, hence, this study evaluated the effect of larger-sized interbody cages on the cervical spine with ACDF under both static and cyclic loading. Method: Twenty pre-operative personalized poro-hyperelastic finite element (FE) models were developed. ACDF post-operative models were then constructed and four clinical scenarios (i.e., 1) No-distraction; 2) 1 mm distraction; 3) 2 mm distraction; and 4) 3 mm distraction) were predicted for each patient. The biomechanical responses at adjacent spinal levels were studied subject to static and cyclic loading. Non-parametric Friedman statistical comparative tests were performed and the p values less than 0.05 were reflected as significant. Results: The calculated intersegmental range of motion (ROM) and intradiscal pressure (IDP) from 20 pre-operative FE models were within the overall ranges compared to the available data from literature. Under static loading, greater ROM, IDP, facet joint force (FJF) values were detected post ACDF, as compared with pre-op. Over-distraction induced significantly higher IDP and FJF in both upper and lower adjacent levels in extension. Higher annulus fibrosus stress and strain values, and increased disc height and fluid loss at the adjacent levels were observed in ACDF group which significantly increased for over-distraction groups. Discussion: it was concluded that using larger-sized interbody cages (the height of ≥2 mm of the index disc height) can result in remarkable variations in biomechanical responses of adjacent levels, which may indicate as risk factor for adjacent segment disease. The results of this comprehensive FE investigation using personalized modeling technique highlight the importance of selecting the appropriate height of interbody cage in ACDF surgery.

Anatomical parameters alter the biomechanical responses of adjacent segments following lumbar fusion surgery: Personalized poroelastic finite element modelling investigations.

Introduction: While the short-term post-operative outcome of lumbar fusion is satisfying for most patients, adjacent segment disease (ASD) can be prevalent in long-term clinical observations. It might be valuable to investigate if inherent geometrical differences among patients can significantly alter the biomechanics of adjacent levels post-surgery. This study aimed to utilize a validated geometrically personalized poroelastic finite element (FE) modeling technique to evaluate the alteration of biomechanical response in adjacent segments post-fusion. Methods: Thirty patients were categorized for evaluation in this study into two distinct groups [i.e., 1) non-ASD and 2) ASD patients] based on other long-term clinical follow-up investigations. To evaluate the time-dependent responses of the models subjected to cyclic loading, a daily cyclic loading scenario was applied to the FE models. Different rotational movements in different planes were superimposed using a 10 Nm moment after daily loading to compare the rotational motions with those at the beginning of cyclic loading. The biomechanical responses of the lumbosacral FE spine models in both groups were analyzed and compared before and after daily loading. Results: The achieved comparative errors between the FE results and clinical images were on average below 20% and 25% for pre-op and post-op models, respectively, which confirms the applicability of this predictive algorithm for rough pre-planning estimations. The results showed that the disc height loss and fluid loss were increased for the adjacent discs in post-op models after 16 h of cyclic loading. In addition, significant differences in disc height loss and fluid loss were observed between the patients who were in the non-ASD and ASD groups. Similarly, the increased stress and fiber strain in the annulus fibrosus (AF) was higher in the adjacent level of post-op models. However, the calculated stress and fiber strain values were significantly higher for patients with ASD. Discussion: Evaluating the biomechanical response of pre-op and post-op modeling in the non-ASD and ASD groups showed that the inherent geometric differences among patients cause significant variations in the estimated mechanical response. In conclusion, the results of the current study highlighted the effect of geometrical parameters (which may refer to the anatomical conditions or the induced modifications regarding surgical techniques) on time-dependent responses of lumbar spine biomechanics.

The weight of computer mouse affects the wrist motion and forearm muscle activity during fast operation speed task.

The frequent use of the computer mouse was reported to be associated with the development of the musculoskeletal disorders in the wrist, forearm, and shoulder regions. This study was to examine the effect of the mouse weights and operation speeds on the wrist motion and muscle activity. 25 subjects (20 males and 5 females) were instructed to repetitively point-and-click the mouse between two targets displaced in the monitor with five different weighted mice (weights around 70, 100, 130, 160, and 190 g) at the fast (50 repetition/min) and slow (25 repetition/min) operation speeds. Surface electromyographic activity of the extensor carpi radialis, extensor carpi ulnaris, extensor digitorum, and upper trapezius muscles were recorded, and the electrogoniometer was used to register the wrist motions. The results showed that the maximal ulnar deviation was not significantly different among the examined conditions. The wrist movement range and the forearm muscle activities showed a V-shape tendency with the lowest value in the mouse weight of 130 g. This tendency was diminished during the slow speed tasks. The results suggested that the proper mouse weight could benefit the users in terms of increasing the movement efficiency and decreasing the muscular costs.

Comparisons of Lumbar Muscle Performance Between Minimally-Invasive and Open Lumbar Fusion Surgery at 1-Year Follow-Up.

STUDY DESIGN: Prospective study. OBJECTIVE: Minimally-invasive lumbar fusion surgery (MIS) is a viable alternative to conventional open surgery (COS) for spinal disorders. Although MIS seems to be associated with less para-spinal muscle trauma, the actual back muscle performance after MIS and COS remain controversial. This study investigated post-operative para-spinal muscle performance, and the correlation between muscle dysfunction and clinical outcome. METHODS: In this prospective, non-randomized control study, 50 patients were enrolled and split into 2 groups: COS and MIS. We established a biomechanical model of the para-spinal muscle in the lumbar spine using electromyography (EMG) and specific muscle function tests. Functional outcomes were also reviewed and analyzed. All patients underwent EMG pre-operatively, and at 3 months and 1 year post-operatively. The para-spinal muscle performance was investigated by comparing the back muscle co-contraction ratio and the load transmission zone to the pre-operative data. RESULTS: Twenty-one patients in the COS group and 25 in the MIS group completed the study. Both groups showed a significant improved functional score. The abdominal and back muscle strengths were decreased post-operatively, and were then increased at 12 months post-operatively in both groups. During the perturbed balance task and static task, the MIS group exhibited a trend of recovery in comparison with the COS group. But, the back muscle performance at 12 months was poorer than the pre-op performance in both groups. CONCLUSIONS: There was no significant difference in clinical outcome and para-spinal muscle performance between groups. In both methods, the global muscle function had declined post-operatively.