A comparison of balance performance: computerized dynamic posturography and a random motion platform

Relationship between Kinesiophobia and Dynamic Postural Stability after Anterior Cruciate Ligament Reconstruction: A Prospective Cohort Study

INTRODUCTION

 Anterior cruciate ligament (ACL) injuries in young, active patients generally require ACL reconstruction (ACLR) to restore mechanical and postural stability. The fear of movement or reinjury (kinesiophobia) has become increasingly recognized in the post-ACLR population; however, the association between restoration of postural stability and kinesiophobia remains largely unknown. The purpose of this study was to investigate changes in mean Tampa Scale of Kinesiophobia-11 (TSK-11), dynamic motion analysis (DMA) scores, and time on the testing platform, as well as any correlation between TSK-11 and mean overall and individual translational and rotational DMA scores during the first 12 months following ACLR.

DESIGN

 Cohort study.

METHODS

 Patients undergoing ACLR were prospectively enrolled and dynamic postural stability and kinesiophobia based on the TSK-11 were collected within 2 days prior to surgery and at 6 and 12 months following ACLR. Dynamic postural stability was quantified by calculating a DMA score, with score calculated in three translational (anterior/posterior [AP], up/down [UD], medial/lateral [ML]) and three rotational (left/right [LR], flexion/extension, and internal/external rotation) independent planes of motions. Correlations between DMA and TSK-11 scores at each time point were analyzed.

RESULTS

 A total of 25 patients meeting inclusion criteria were analyzed. Mean overall DMA and TSK-11 scores increased with each successive testing interval. At 6-month follow-up, a weakly positive association between TSK-11 and DMA scores was appreciated based on overall DMA, AP, UD, ML, and LR. At 12 months, a moderately positive correlation was appreciated between TSK-11 and the translational, but not rotational, planes of motion.

CONCLUSIONS

 Following ACLR, lower level of kinesiophobia were found to be moderately associated with improved dynamic stability, especially in the translation planes of motion.

Difference in the recruitment of intrinsic foot muscles in the elderly under static and dynamic postural conditions

Background

The effect of foot, especially intrinsic muscles, on postural control and its related mechanisms remain unclear due to the complex structure. Therefore, this study aims to investigate the activation of intrinsic foot muscles in the elderly under static and dynamic postural tasks.

Methods

Twenty-one elderly participants were included to perform different postural tests (sensory organization test (SOT), motor control test (MCT), limit of stability test (LOS), and unilateral stance test) by a NeuroCom Balance Manager System. The participants were instructed to maintain postural stability under conditions with combined different sensory inputs (vision, vestibular, and proprioception) in SOT as well as conditions with translation disturbance in MCT, and to perform an active weight-shifting tasks in LOS. During these tasks, muscle activation were simultaneously acquired from intrinsic foot muscles (abductor halluces (AbH) and flexor digitorum brevis (FDB)) and ankle muscles (anterior tibialis, medial head of gastrocnemius, lateral head of gastrocnemius, and peroneus longus). The root-mean-square amplitude of these muscles in postural tasks was calculated and normalized with the EMG activity in unilateral stance task.

Results

The activation of intrinsic foot muscles significantly differed among different SOT tasks (p < 0.001). Post-hoc tests showed that compared with that under normal condition 1 without sensory interference, EMGs increased significantly under sensory disturbance (conditions 2-6). By contrast, compared with that under the single-sensory disturbed conditions (conditions 2-4; 2 for disturbed vision, 3 for disturbed vestibular sensation, 4 for disturbed proprioception), activation was significantly greater under the dual-sensory disturbed postural tasks (conditions 5 and 6; 5 for disturbed vision and proprioception, 6 for disturbed vestibular sensation and proprioception). In MCT, EMGs of foot muscles increased significantly under different translation speeds (p < 0.001). In LOS, moderate and significant correlations were found between muscle activations and postural stability parameters (AbH, r = 0. 355-0.636, p < 0.05; FDB, r = 0.336-0.622, p < 0.05).

Conclusion

Intrinsic foot muscles play a complementary role to regulate postural stability when disturbances occur. In addition, the recruitment magnitude of intrinsic foot muscles is positively correlated with the limit of stability, indicating their contribution to increasing the limits of stability in the elderly.

Appropriate Image Selection With Virtual Reality in Vestibular Rehabilitation: Cross-sectional Study

BACKGROUND

While vestibular rehabilitation with virtual reality (VR) is becoming more popular every day, the disadvantages of this method are not yet clear.

OBJECTIVE

The aim of this study is to examine the effect of the image to be used in vestibular rehabilitation with VR on the systems that provide body posture.

METHODS

The study was carried out with 36 participants (18 women and 18 men) aged 18 to 30 years. To assess balance control components separately, a sensory organization test was administered to the participants in the presence of stressful and relaxing environment images with VR technology. The State-Trait Anxiety Inventory survey was also used to measure the stress values in the created environments.

RESULTS

The State-Trait Anxiety Inventory survey revealed that while stressful videos significantly increased stress, relaxing videos reduced stress. Among measurements obtained in the presence of VR, significant decreases were observed mostly in the visual system data. A significant increase in vestibular system data (P=.01) was observed with a decrease in visual system data (P<.001) when the relaxing image was presented. Additionally, there was a significant difference in the somatosensory (P=.001), composite (P=.002), and visual system (P<.001) data in the presence of stressful videos.

CONCLUSIONS

Although the use of a VR system for vestibular rehabilitation is relatively new, no extant studies have examined how the image type used in VR can affect the integration of visual system data. Therefore, this study is unique in terms of showing the effects of the stress created by the change in the type of the image used in VR. When VR technology is used for therapeutic vestibular rehabilitation for patients whose balance disorder is due to the vestibular system, stress-free videos should be used. However, the use of stressful videos in VR technology will be beneficial in the rehabilitation of those with balance disorders due to the somatosensory system.

Feasibility and Application of the B.E.A.T. Testbed for Assessing the Effects of Lower Limb Exoskeletons on Human Balance

Assessing the performance of exoskeletons in assisting human balance is important for their design process. This study proposes a novel testbed, the B.E.A.T (Balance Evaluation Automated Testbed) to address this aim. We applied the B.E.A.T to evaluate how the presence of a lower limb exoskeleton influenced human balance. The B.E.A.T. consists of a robotic platform, standardized protocols, and performance indicators. Fifteen healthy subjects were enrolled and subjected to repeatable step-type ground perturbations in different directions using the multi-axis robotic platform. Each participant performed three trials, both with and without the exoskeleton (EXO and No-EXO conditions). Nine performance indicators, divided into kinematic and body stability indicators, were computed. The reliability of performance indicators was assessed by computing the Inter Class Correlation (ICC). The indicators showed good (0.60 ≤ ICC < 0.75) to excellent (ICC ≥ 0.75) reliability. The comparison between the EXO and No-EXO conditions revealed a significant increase in the joint range of motion and the center of pressure displacement while wearing the exoskeleton. The main differences between the EXO and No-EXO conditions were found in the range of motion of the knee joints, with an increment up to 17° in the sagittal plane.

Changes in Dynamic Postural Stability After ACL Reconstruction: Results Over 2 Years of Follow-up

Background:

The anterior cruciate ligament (ACL) is crucial for knee proprioception and postural stability. While ACL reconstruction (ACLR) and rehabilitation improve postural stability, the timing in improvement of dynamic postural stability after ACLR remains relatively unknown.

Purpose:

To evaluate changes in dynamic postural stability after ACLR out to 24 months postoperatively.

Study Design:

Case series; Level of evidence, 4.

Methods:

Patients undergoing ACLR were prospectively enrolled, and dynamic postural stability was assessed within 2 days before surgery, at 3-month intervals postoperatively to 18 months, then at 24 months. Measurements were made on a multidirectional platform tracking the patient’s center of mass based on pelvic motion. The amount of time the patient was able to stay on the platform was recorded, and a dynamic motion analysis score, reflecting the patient’s ability to maintain one’s center of mass, was generated overall and in 6 independent planes of motion.

Results:

A total of 44 patients with a mean age of 19.7 ± 6.2 years completed the study protocol. Overall mean dynamic postural stability improved significantly at 3, 6, 9, and 12 months after surgery, with continued improvement out to 24 months. Notable improvements occurred in medial/lateral and anterior/posterior stability from baseline to 6 months postoperatively, while internal/external rotation and flexion/extension stability declined initially after surgery from baseline to 3 months postoperatively before stabilizing to the end of the study period.

Conclusion:

Overall dynamic postural stability significantly improved up to 12 months after ACLR. Improvement in postural stability occurred primarily in the medial/lateral and anterior/posterior planes of motion, with initial decreases in the flexion/extension and internal/external rotational planes of motion.

Concussion Baseline Retesting Is Necessary When Initial Scores Are Low

OBJECTIVE

To determine whether (1) initial baseline scores are significantly better for those who have valid (initial valid) versus invalid scores (initial invalid) on their concussion baseline testing, (2) retesting results in significantly improved baseline scores, and (3) there is a significant difference in scores between those who have valid scores on their initial attempt and those who retook baseline tests (retest valid).

DESIGN

Prospective, repeated-measures.

SETTING

Two years of collegiate preparticipation concussion baseline testing.

PARTICIPANTS

Five hundred forty-seven male and female Division I collegiate athletes (19.02 ± 1.31 years, female = 217).

INDEPENDENT VARIABLES

Participants were divided into initial valid and initial invalid. The retest group was further divided into their initial (initial invalid) and final valid attempt (retest valid).

MAIN OUTCOME MEASURES

Data were analyzed to determine the relationship between the 3 groups and overall initial and final scores on 28 individual items: total symptoms score, coordination, near-point convergence, CNS Vital Signs (CNSVS), Senaptec Sensory Station, and Neurocom Sensory Organization Test (SOT).

RESULTS

The initial valid group scored significantly better than the initial invalid group on 8 CNSVS items and 5 Senaptec items (P < 0.002). The retest valid scores were significantly better compared with the initial invalid scores on 17 items (P < 0.002).

CONCLUSIONS

Retesting is recommended for individuals who score below acceptable ranges. This is important because athletes may experience a learning effect and are highly motivated during postinjury testing, so accurate baseline scores are imperative for athlete safety. Completion time for the coordination test may be a more informative option.

Measuring Vestibular Contributions to Age-Related Balance Impairment: A Review

Aging is associated with progressive declines in both the vestibular and human balance systems. While vestibular lesions certainly contribute to imbalance, the specific contributions of age-related vestibular declines to age-related balance impairment is poorly understood. This gap in knowledge results from the absence of a standardized method for measuring age-related changes to the vestibular balance pathways. The purpose of this manuscript is to provide an overview of the existing body of literature as it pertains to the methods currently used to infer vestibular contributions to age-related imbalance.

Decreased Postural Control in Patients Undergoing Anterior Cruciate Ligament Reconstruction Compared to Healthy Controls

CONTEXT

Patients with anterior cruciate ligament (ACL) tears are likely to have deficient dynamic postural stability compared with healthy sex- and age-matched controls.

OBJECTIVES

To test the hypothesis that patients undergoing ACL reconstruction have decreased dynamic postural stability compared with matched healthy controls.

DESIGN

Prospective case-control study.

SETTING

Orthopedic sports medicine and physical therapy clinics.

PATIENTS OR OTHER PARTICIPANTS

Patients aged 20 years and younger with an ACL tear scheduled for reconstruction were enrolled prospectively. Controls were recruited from local high schools and colleges via flyers.

INTERVENTIONS

Patients underwent double-stance dynamic postural stability testing prior to surgery, recording time to failure and dynamic motion analysis (DMA) scores. Patients were then matched with healthy controls.

MAIN OUTCOME MEASURES

Demographics, time to failure, and DMA scores were compared between groups.

RESULTS

A total of 19 females and 12 males with ACL tears were matched with controls. Individuals with ACL tears were more active (Marx activity score: 15.7 [1.0] vs 10.8 [4.9], P < .001); had shorter times until test failure (84.4 [15.8] vs 99.5 [14.5] s, P < .001); and had higher (worse) DMA scores (627 [147] vs 481 [132], P < .001), indicating less dynamic postural stability. Six patients with ACL deficiency (1 male and 5 females) demonstrated lower (better) DMA scores than their controls, and another 7 (4 males and 3 females) were within 20% of controls.

CONCLUSIONS

Patients undergoing ACL reconstruction had worse global dynamic postural stability compared with well-matched controls. This may represent the effect of the ACL injury or preexisting deficits that contributed to the injury itself. These differences should be studied further to evaluate their relevance to ACL injury risk, rehabilitation, and return to play.

Test-retest reliability and minimal detectable change of the computerized dynamic posturography PROPRIO for adults with chronic traumatic brain injury

PURPOSE

Balance deficits after brain injury, including reactive recovery from unexpected perturbations, can persist well after rehabilitation is concluded. While traditional clinical assessments are practical, the anticipatory nature of the tasks may mask perceptible balance control. Computerized dynamic posturography can directly quantify capacity to respond to unexpected, external perturbations. This study examined the reliability of the computerized dynamic posturography assessment with the device PROPRIO^® 4000 in adults with traumatic brain injury and created the minimal detectable change for its standardized test.

METHODS

Ten adults (ages 21-55 years) with chronic (average 10 ± 6 years post-injury) severe (loss of consciousness 2-75 days) brain injury performed three trials of the Propriotest^® on two separate days. The average of three trials and the best scores were used separately for analysis. Test-retest reliability was verified using Intraclass Correlation Coefficients with 95% confidence interval and standard error of measurement in relation to the Intraclass Correlation Coefficients at 95%. The minimal detectable change was calculated at 95% confidence level (minimal detectable change₉₅) and Bland-Altman plots were created to express agreement between measurement days.

RESULTS

The results exhibited excellent reliability for both average (Intraclass Correlation Coefficient of 0.969, standard error of measurement 50.9 points) and best (Intraclass Correlation Coefficient of 0.985, standard error of measurement 31.3 points) scores, with average and best minimal detectable change₉₅ of 141.0 and 86.7 points, respectively.

CONCLUSIONS

Clinicians and rehabilitation researchers can use these findings to determine if a Propriotest^® change score represents a true post-treatment effect with adults with chronic brain injury.IMPLICATIONS FOR REHABILITATIONAfter brain injury, balance deficits are common and can persist well after completion of rehabilitation programs.Computerized dynamic posturography allows for objective quantification of one's capacity to respond to external perturbations.The device PROPRIO^® 4000 provides reliable quantification of balance deficits of community dwelling individuals who have experienced a severe traumatic brain injury.The minimal detectable change scores created can assist clinicians and rehabilitation researchers detect whether a change in balance score represents a true effect of an intervention at post-treatment.

Every hit matters: White matter diffusivity changes in high school football athletes are correlated with repetitive head acceleration event exposure

Recent evidence of short-term alterations in brain physiology associated with repeated exposure to moderate intensity subconcussive head acceleration events (HAEs), prompts the question whether these alterations represent an underlying neural injury. A retrospective analysis combining counts of experienced HAEs and longitudinal diffusion-weighted imaging explored whether greater exposure to incident mechanical forces was associated with traditional diffusion-based measures of neural injury—reduced fractional anisotropy (FA) and increased mean diffusivity (MD). Brains of high school athletes (N = 61) participating in American football exhibited greater spatial extents (or volumes) experiencing substantial changes (increases and decreases) in both FA and MD than brains of peers who do not participate in collision-based sports (N = 15). Further, the spatial extents of the football athlete brain exhibiting traditional diffusion-based markers of neural injury were found to be significantly correlated with the cumulative exposure to HAEs having peak translational acceleration exceeding 20 g. This finding demonstrates that subconcussive HAEs induce low-level neurotrauma, with prolonged exposure producing greater accumulation of neural damage. The duration and extent of recovery associated with periods in which athletes do not experience subconcussive HAEs now represents a priority for future study, such that appropriate participation and training schedules may be developed to minimize the risk of long-term neurological dysfunction.

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Brain volumes evidencing injury are larger in football athletes than controls.

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Spatial extent of decreased FA correlates with head acceleration event exposure.

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Spatial extent of increased MD correlates with head acceleration event exposure.

The correlation between white matter hyperintensity and balance disorder and fall risk: An observational, prospective cohort study

OBJECTIVE

The presence of an association between white matter hyperintensity (WMH) and the risk of falls in older people is uncertain, with little supporting prospective evidence available at present. We aimed to determine whether WMH was associated with dysfunctions of balance and gait, and other sensorimotor factors leading to falls, and the independent factors related to falls in older Chinese people. The protective effect of exercise against falls was also addressed.

METHODS

In a representative sample of hospital-based individuals aged 50 years and older in China, the patients' history of falls, magnetic resonance imaging data, scores on the 9-item Berg Balance Scale (BBS-9) test and timed up-and-go test (TUGT), and sensorimotor measures of computerized dynamic posturography (CDP) were analyzed. Incident falls were recorded prospectively over a 12-month period. Using regression modeling, the association between the risk of falls and baseline WMH was estimated.

RESULTS

Only individuals with severe WMH were at an increased risk of falls, and CDP was more sensitive than BBS-9 in detecting WMH-related balance and gait dysfunction. However, WMH was not an independent predictor of falls. Taller height and overweight or obese body habitus were identified as novel protective factors for falls. Female, fall history, and increased TUGT score were identified as independent risk factors for falls in older Chinese people.

CONCLUSION

Although WMH was associated with an increased risk of falls, it was not an independent predictor.

Postural Stability in Older Adults with a Distal Radial Fracture

BACKGROUND

The physical risk factors leading to distal radial fractures are poorly understood. The goal of this study was to compare postural stability between older adults with and without a prior distal radial fragility fracture.

METHODS

This case-control evaluation was performed at a single tertiary institution. The fracture cohort comprised 23 patients treated for a low-energy distal radial fracture within 6 to 24 months prior to this study. Twenty-three age and sex-matched control participants, without a prior fragility fracture, were selected from an outpatient clinic population. All participants completed a balance assessment with a computerized balance platform device. Dynamic motion analysis (DMA) scores ranging from 0 to 1,440 points are produced, with lower scores indicating better postural stability. Participants also completed validated questionnaires for general health quality (EuroQol-5D-3L [EQ-5D-3L]) and physical activity (Physical Activity Scale for the Elderly [PASE]) and comprehensive health and demographic information including treatment for compromised balance or osteoporosis. Statistical analysis compared data between cases and controls using either the Student t test or the Mann-Whitney U test.

RESULTS

There were no significant differences (p > 0.05) in age, sex, body mass index, physical activity score, or EQ-5D-3L general health visual analog scale score between participants with or without prior distal radial fracture. The fracture cohort demonstrated poorer balance, with higher DMA scores at 933 points compared with 790 points for the control cohort (p = 0.008). Nineteen patients (83%) in the fracture cohort reported having dual x-ray absorptiometry (DXA) scans within 5 years prior to this study, but only 2 patients (9%) had ever been referred for balance training with physical therapy.

CONCLUSIONS

Older adults who sustain low-energy distal radial fractures demonstrate impaired postural stability compared with individuals of a similar age who have not sustained such fractures. Following a distal radial fracture, these patients may benefit from interventions to improve postural stability.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Young Females Exhibit Decreased Coronal Plane Postural Stability Compared to Young Males

BACKGROUND

Female athletes are at significantly higher risk of noncontact ACL injury than males, particularly in pivoting sports such as soccer and basketball. Sex-based differences in proprioception and core stability may contribute to this elevated risk.

QUESTIONS/PURPOSE

This study evaluates a novel method of assessing dynamic stability to test the hypothesis that healthy adolescent controls have sex-based differences in postural stability.

METHODS

Seventy-nine male and 72 female subjects completed three rounds of dynamic postural stability testing. During the assessment, subjects attempted to stabilize their torso and upper body in response to random movements of the platform. The total time a subject lasted on the platform and dynamic motion analysis (DMA) score, a summation of motion in five planes throughout testing, was calculated for each subject. The average score for each subject was included in the analysis.

RESULTS

Males lasted longer on the platform (98 ± 14 s) than females (94 ± 13 s) (p = 0.04). Coronal plane and rotation stability differed significantly between genders (323 ± 126 vs. 365 ± 128, p = 0.04) and (318 ± 82 vs. 403 ± 153, p = 0.0002), respectively. No statistically significant difference was seen in the other planes of motion.

CONCLUSIONS

Females have less dynamic postural stability than their male counterparts in the coronal plane based on a novel assessment tool. This finding may contribute to better understanding of sex-based differences in rates of injury such as noncontact ACL tears.

Body balance control deficiencies following ACL reconstruction combined with medial meniscus suture. A preliminary report

INTRODUCTION

Proprioception makes a critical contribution to body balance. The objective of this study was to evaluate static postural control after anterior cruciate ligament (ACL) reconstruction combined with medial meniscus (MM) suture, comparatively to healthy controls.

HYPOTHESIS

Body balance is adversely affected 2 months after ACL reconstruction combined with MM suture.

PATIENTS AND METHODS

Fifteen patients (12 males and 3 females) aged 20 to 35 years (mean, 26.4 ± 6.0 years) who underwent ACL reconstruction with MM suture were compared to 20 healthy, physically active controls (16 females and 4 males) aged 19 to 23 years (mean, 21.1 ± 1.8 years), most of whom were physiotherapy students. Mean age was not significantly different between the patients and controls. A balance platform was used to estimate static postural control parameters. Each participant performed four tests, two in normal bipedal stance and two in tandem stance; in each stance, one test was done with the eyes open and the other with the eyes closed. We analysed global scores on a standardised 100-point scale and mean centre of pressure (COP) displacement velocity in the sagittal and frontal planes.

RESULTS

Body balance was impaired 2 months after ACL reconstruction with MM suture. Thus, the patients had lower global scores and higher mean COP velocities in both the coronal and sagittal planes.

CONCLUSIONS

Proprioception is impaired after ACL reconstruction with MM suture. Lack of visual control significantly decreases the ability to maintain balance. A balance platform is a useful diagnostic tool for patients with ACL reconstruction and MM suture.

LEVEL OF EVIDENCE

Level II.

The effect of text messaging on reactive balance and the temporal and spatial characteristics of gait

The aim of this study was to determine the effects text messaging has on gait characteristics and reactive balance. Thirty-two subjects were recruited. Data was collected on texting ability in standing, while walking and while in perturbed stance. Data on gait parameters using the GAITRiteTM were collected while walking normally and while walking and texting. Data on reactive balance in perturbed stance (DMA score) using the PROPRIO 5000™ was collected while standing and while standing and texting. Repeated measures statistics were applied. No practical difference in texting ability was found between the three conditions of standing, walking and perturbed stance. A significant difference was found between mean gait characteristics of velocity, cadence, double limb support and mean step length during normal walking and walking while texting (p<.05). No statistical significance was shown between mean heel to heel support. A significant difference was found between reactive balance ability (mean DMA score) in perturbed stance and perturbed stance while texting (p<.05). The data imply that gait and balance are negatively impacted while texting and that subjects will maintain their baseline texting speed and accuracy at the expense of gait speed and impaired balance.

Hip resurfacing does not improve proprioception compared with THA

BACKGROUND

Proposed benefits of total hip resurfacing arthroplasty over total hip arthroplasty (THA) include better proprioception, but this has not been rigorously tested or validated.

QUESTIONS/PURPOSES

Our purpose was to apply an advanced testing device that objectively quantifies dynamic postural stability to determine if total hip resurfacing is associated with improved proprioception compared with standard or large-head THA.

METHODS

Three groups of 25 patients (total hip resurfacing, THA femoral head > 32 mm, THA femoral head ≤ 32 mm) and a matched control group were recruited. All participants had UCLA scores ≥ 5 and Harris hip scores ≥ 90 at the time of testing. Testing was conducted using a commercially available device that uses a multidirectional, powered platform to measure deviations of the center of mass and consisted of trials with both double- and single-limb support.

RESULTS

Double-limb testing showed no differences between groups. In single-limb testing, the operative side performed better in patients who had undergone total hip resurfacing versus THA, but this difference disappeared when the operative side was normalized to the nonoperative side. When compared with control subjects who had not had arthroplasty, both operative and nonoperative sides showed significantly worse proprioception for all arthroplasty cohorts, suggesting that decreased proprioception is associated with arthritis of the hip in young adults.

CONCLUSIONS

Total hip resurfacing arthroplasty did not result in improved proprioception compared with THA. These results tend to refute the concept that improved proprioception is a rationale for selecting total hip resurfacing over THA in young patients.

Fragile x-associated tremor ataxia syndrome: the expanding clinical picture, pathophysiology, epidemiology, and update on treatment

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a progressive degenerative movement disorder characterized by kinetic tremor, cerebellar gait ataxia, parkinsonism, and cognitive decline. This disorder occurs in both males and females, frequently in families with children who have fragile X syndrome. The clinical features of this disorder, both classic and newly described, are summarized in this paper. In screening studies, fragile X mental retardation 1 (FMR1) gene premutation (55–200 CGG) expansions are most frequently seen in men with ataxia who have tested negative for spinocerebellar ataxias. Since the original description, the classic FXTAS phenotype has now been reported in females and in carriers of smaller (45–54 CGG) and larger (>200 CGG) expansions in FMR1. Premutation carriers may present with a Parkinson disease phenotype or hypotension, rather than with tremor and/or ataxia. Parkinsonism and gait ataxia may also be seen in individuals with gray zone (41–54 CGG) expansions. Studies regarding medication to treat the symptoms in FXTAS are few in number and suggest that medications targeted to specific symptoms, such as kinetic tremor or gait ataxia, may be most beneficial. Great progress has been made in regards to FXTAS research, likely given the readily available gene test and the screening of multiple family members, including parents and grandparents, of fragile X syndrome children. Expansion of genotypes and phenotypes in the disorder may suggest that a broader disease definition might be necessary in the future.

A 3-DOF parallel robot with spherical motion for the rehabilitation and evaluation of balance performance

In this paper a novel electrically actuated parallel robot with three degrees-of-freedom (3 DOF) for dynamic postural studies is presented. The design has been described, the solution to the inverse kinematics has been found, and a numerical solution for the direct kinematics has been proposed. The workspace of the implemented robot is characterized by an angular range of motion of about ±10° for roll and pitch when yaw is in the range ±15°. The robot was constructed and the orientation accuracy was tested by means of an optoelectronic system and by imposing a sinusoidal input, with a frequency of 1 Hz and amplitude of 10°, along the three axes, in sequence. The collected data indicated a phase delay of 1° and an amplitude error of 0.5%-1.5%; similar values were observed for cross-axis sensitivity errors. We also conducted a clinical application on a group of normal subjects, who were standing in equilibrium on the robot base with eyes open (EO) and eyes closed (EC), which was rotated with a tri-axial sinusoidal trajectory with a frequency of 0.5 Hz and amplitude 5° for roll and pitch and 10° for the yaw. The postural configuration of the subjects was recorded with an optoelectronic system. However, due to the mainly technical nature of this paper, only initial validation outcomes are reported here. The clinical application showed that only the tilt and displacement on the sagittal pane of head, trunk, and pelvis in the trials conducted with eyes closed were affected by drift and that the reduction of the yaw rotation and of the mediolateral translation was not a controlled parameter, as happened, instead, for the other anatomical directions.

Integrated musculoskeletal rehabilitation care at a comprehensive combat and complex casualty care program

OBJECTIVE

The purpose of this study is to describe the musculoskeletal rehabilitation model used to care for combat and severely wounded or ill US military service members at an integrated Comprehensive Combat and Complex Casualty Care center located at Naval Medical Center San Diego.

METHODS

Through a collaborative and iterative process, providers from the various services included at the Comprehensive Combat and Complex Casualty Care program developed a description of the integration of services provided at this location.

RESULTS

After construction of the facility in 2007, the program has provided services for approximately 2 years. Eighteen different health care providers from 10 different specialties provide integrated musculoskeletal services, which include primary care, physical therapy, occupational therapy, vestibular therapy, gait analysis, prosthetics, recreational therapy, and chiropractic care. At the time of this writing (early 2009), the program had provided musculoskeletal rehabilitation care to approximately 500 patients, 58 with amputations, from the operational theater, Veterans Affairs, other military treatment facilities, and local trauma centers.

CONCLUSION

The complex nature of combat wounded and polytrauma patients requires an integrated and interdisciplinary team that is innovative, adaptable, and focused on the needs of the patient. This article presents a description of the model and the experiences of our musculoskeletal rehabilitation team; it is our hope that this article will assist other centers and add to the small but emerging literature on this topic.

Moment measurement accuracy of a parallel spherical robot for dynamic posturography

This paper characterizes the moment measurement accuracy for a novel parallel spherical robot (SR) for dynamic posturography, controllable by position or impedance. The SR consists of three linear motors placed on a support base, a moving base, and three passive arms equipped with uniaxial load cells permitting impedance controlled perturbations. To evaluate the accuracy, a subject stood still on the SR, set in position control mode, while selected sinusoidal trajectories were applied. The moments computed by the load cells were compared to the value measured by a six-component force platform, placed on top of the rotating base. For the intended application of the SR, the errors were negligible with the worse case of only 4 Nm in a total of 15 trials (five conditions, three repetitions). The observed moment error was related mainly to the intrinsic accuracy of the sensors, equal to about 7 N. To demonstrate clinical applicability, the platform was set to impedance control mode and a protocol was tested with a 12-year-old girl with brain injury and a group of four healthy subjects. In total, 24 trials (eight conditions, three repetitions) were recorded for each subject. The results of this pilot study identified distinctive postural behaviors and therefore showed that the SR can be considered as an effective tool for dynamic posturography.