Elevated plasma neurofilament light chain in immune-mediated neurological disorders (IMND) detected by immunomagnetic reduction (IMR)

BACKGROUND

In cases of immune-mediated neurological disorders (IMND), different syndromes are associated with antibodies against neuronal surface antigens, intra-neuronal antigens, astrocytic aquaporin, and gangliosides. These autoantibodies can be pathogenic or connected to neuroinflammation and resulting neuronal injuries. This study aims to identify a blood biomarker that can detect neuronal damage in individuals with IMND. To this end, we use immunomagnetic reduction (IMR) nanobead technology to measure plasma neurofilament light chain (NfL).

METHODS

The patients with IMND were enrolled in the Chang Gung Memorial Hospital at Keelung from 2018 to 2023. Seronegative patients were excluded based on the results of antibody tests. The healthy controls (HC) were community-dwelling adults from the Northeastern Taiwan Community Medicine Research Cohort (NTCMRC) conducted by the Community Medicine Research Center of the Keelung CGMH from 2020 to 2022. IMR technique detects magnetic susceptibility via measuring magnetic signal reduction caused by antigen-antibody immunocomplex formation on magnetic nanobeads. The plasma level of NfL was determined by the magnetic susceptibility changes in IMR.

RESULTS

The study enrolled 57 IMND patients from the hospital and 73 HC participants from the communities. The plasma NfL was significantly higher in the IMND than in the HC (11.022 ± 2.637 vs. 9.664 ± 2.610 pg/mL, p = 0.004), regardless of age effects on plasma NfL in an analysis of covariance (ANCOVA) (F = 0.720, p = 0.950). In the receiver of operation curve analysis, the area under curve for plasma NfL to discriminate IMND and HC was 0.664 (95% CI = 0.549 to 0.739, p = 0.005). The subgroup analysis of plasma NfL in the IMND patients showed no difference between peripheral immune-mediated neuropathy (IMN) and central immune-mediated encephalomyelitis (IMEM) (11.331 ± 2.895 vs. 10.627 ± 2.260 pg/mL, p = 0.322), nor between tumor and non-tumor IMND (10.784 ± 3.446 vs. 11.093 ± 2.391 pg/mL, p = 0.714). Additionally, the antibody class of ganglioside antibodies in IMN did not have an impact on plasma NfL level (p = 0.857).

CONCLUSION

Plasma NfL measurement is a reliable indicator of axonal injuries in patients with IMND. It is equally effective in detecting nerve injuries in inflammatory peripheral neuropathies and central neuroinflammation. The IMR nanobead technology offers a feasible method of detecting plasma NfL, which helps identify axonal injuries in IMND.

Case Report: Plasma Biomarkers Reflect Immune Mechanisms of Guillain-Barré Syndrome

This case series reported a group of patients with Guillain–Barré syndrome (GBS) and their plasma cytokine changes before and after immunotherapy. We aimed to understand GBS's pathogenesis and pathophysiology through observing the interval differences of the representative cytokines, which were the thymus and activation regulated chemokine (TARC) for T-cell chemotaxis, CD40 ligand (CD40L) for cosimulation of B and T cells, activated complement component C5/C5a, and brain-derived neurotrophic factor (BDNF) for survival and regenerative responses to nerve injuries. The fluorescence magnetic bead-based multiplexing immunoassay simultaneously quantified the five cytokines in a single sample. From June 2018 to December 2019, we enrolled five GBS patients who had completed before–after blood cytokine measurements. One patient was diagnosed with paraneoplastic GBS and excluded from the following cytokine analysis. The BDNF level decreased consistently in all the patients and made it a potential biomarker for the acute stage of GBS. Interval changes of the other four cytokines were relatively inconsistent and possibly related to interindividual differences in the immune response to GBS triggers, types of GBS variants, and classes of antiganglioside antibodies. In summary, utilizing the multiplexing immunoassay helps in understanding the complex immune mechanisms of GBS and the variation of immune responses in GBS subtypes; this method is feasible for identifying potential biomarkers of GBS.

Association between Pre-Existing Coronary Artery Disease and 5-Year Mortality in Stroke Patients with High-Grade Carotid Artery Stenosis

BACKGROUND

The coincidence of coronary artery disease (CAD) and carotid artery stenosis (CAS) was observed. However, the association between pre-existing CAD and ischemic stroke (IS) outcome in patients with high-grade CAS remains unclear. We aimed to investigate the association between pre-existing CAD and outcomes of acute IS patients with high-grade CAS.

METHODS

From January 1, 2007, to April 30, 2012, we enrolled 372 acute IS patients with high-grade CAS and prospectively observed them for 5 years. Demographic features, vascular risk factors, comorbidities, and outcomes were compared between patients with and without pre-existing CAD.

RESULTS

Among 372 individuals, 75 (20.2%) patients had pre-existing CAD and 297 (79.8%) patients did not have pre-existing CAD. The prevalence rates of hypertension, congestive heart failure, chronic kidney disease, and gout in patients with pre-existing CAD were significantly higher than in those without pre-existing CAD (p = 0.017, p < 0.001, p = 0.002, and p < 0.001, respectively). The multivariate Cox proportional hazards model revealed that pre-existing CAD was a significant risk factor for a 5-year all-cause mortality in acute IS patients with high-grade CAS (hazard ratio = 2.26; 95% confidence interval = 1.35-3.79; p = 0.002).

CONCLUSION

Pre-existing CAD was associated with an increased risk of 5-year mortality in acute IS patients with high-grade CAS. Intensive treatment for the pre-existing CAD may reduce long-term mortality in acute IS patients with high-grade CAS.

Different FDG-PET metabolic patterns of anti-AMPAR and anti-NMDAR encephalitis: Case report and literature review

INTRODUCTION

¹⁸ F-fluorodeoxyglucose (FDG)-PET metabolic patterns of brain differ among autoimmune encephalitis with different neuronal surface antigens. In this case report, we compared the topographical relationship of cerebral glucose metabolism and antigen distribution in the patients with anti-NMDAR and anti-AMPAR encephalitis. Literature review summarized the common features of brain metabolism of autoimmune encephalitis.

METHODS

The cerebral glucose metabolism was evaluated by FDG-PET/CT during acute-to-subacute stage of autoimmune encephalitis and after treatment. The stereo and quantitative analysis of cerebral metabolism used standardized z-score and visualized on three-dimensional stereotactic surface projection. To map NMDAR and AMPAR in human brain, we adopted genetic atlases from the Allen Institute and protein atlases from Zilles's receptor densities.

RESULTS

The three-dimensional stereotactic surface projection displayed frontal-dominant hypometabolism in a 66-year-old female patient with anti-AMPAR encephalitis and occipital-dominant hypometabolism in a 29-year-old female patient with anti-NMDAR encephalitis. Receptor density maps revealed opposite frontal-occipital gradients of AMPAR and NMDAR, which reflect reduced metabolism in the correspondent encephalitis. FDG-PET hypometabolic areas possibly represent receptor hypofunction with spatial correspondence to receptor distributions of the autoimmune encephalitis. The reversibility of hypometabolism was in line with patients' cognitive improvement. The literature review summarized six features of metabolic anomalies of autoimmune encephalitis: (a) temporal hypermetabolism, (b) frontal hypermetabolism and (c) occipital hypometabolism in anti-NMDAR encephalitis, (d) hypometabolism in association cortices, (e) sparing of unimodal primary motor cortex, and (e) reversibility in recovery.

CONCLUSIONS

The distinct cerebral hypometabolic patterns of autoimmune encephalitis were representative for receptor hypofunction and topographical distribution of antigenic receptors. The reversibility of hypometabolism marked the clinical recovery of autoimmune encephalitis and made FDG-PET of brain a valuable diagnostic tool.

Evaluation of emissions and exposures at workplaces using desktop 3-dimensional printer

There is a paucity of data on additive manufacturing process emissions and personal exposures in real-world workplaces. Hence, we evaluated atmospheres in four workplaces utilizing desktop "3-dimensional" (3-d) printers [fused filament fabrication (FFF) and sheer] for production, prototyping, or research. Airborne particle diameter and number concentration and total volatile organic compound concentrations were measured using real-time instruments. Airborne particles and volatile organic compounds were collected using time-integrated sampling techniques for off-line analysis. Personal exposures for metals and volatile organic compounds were measured in the breathing zone of operators. All 3-d printers that were monitored released ultrafine and fine particles and organic vapors into workplace air. Particle number-based emission rates (#/min) ranged from 9.4 × 109 to 4.4 × 1011 (n = 9samples) for FFF3-d printers and from 1.9 to 3.8 × 109 (n = 2 samples) for a sheer 3-d printer. The large variability in emission rate values reflected variability from the printers as well as differences in printer design, operating conditions, and feedstock materials among printers. A custom-built ventilated enclosure evaluated at one facility was capable of reducing particle number and total organic chemical concentrations by 99.7% and 53.2%, respectively. Carbonyl compounds were detected in room air; however, none were specifically attributed to the 3-d printing process. Personal exposure to metals (aluminum, iron) and 12 different organic chemicals were all below applicable NIOSH Recommended Exposure Limit values, but results are not reflective of all possible exposure scenarios. More research is needed to understand 3-d printer emissions, exposures, and efficacy of engineering controls in occupational settings.

Association between Atrial Fibrillation and Three-Year Mortality in Nondiabetic Patients with Acute First-Ever Ischemic Stroke

BACKGROUND

Diabetes mellitus (DM) is a risk factor for atrial fibrillation (AF) and is known to be an important risk factor for death from stroke. The influence of AF on long-term outcomes in patients with ischemic stroke remains controversial. To clarify the exact influence of AF on stroke outcome and exclude the effect from DM, we investigated the influence of AF on the 3-year outcomes of nondiabetic patients with acute first-ever ischemic stroke.

METHODS

Five-hundred seventy-four nondiabetic patients with acute first-ever ischemic stroke were enrolled and had been followed for 3 years. Patients were divided into 2 groups according to whether AF was diagnosed or not. Clinical presentations, risk factors for stroke, laboratory data, comorbidities, and outcomes were recorded.

RESULTS

A total of 107 patients (18.6%) had AF. The age was significantly older in patients with AF. Total anterior circulation syndrome occurred more frequently among patients with AF (P < .001). The mean length of stay in the acute ward was significantly higher in patients with AF (P < .001). Furthermore, dependent functional status following discharge was higher in patients with AF (P < .001). Multivariate Cox regression revealed that AF is a significant predictor of 3-year all-cause mortality (hazard ratio = 1.98, 95% confidence interval = 1.07-3.67, P = .022).

CONCLUSIONS

AF is associated with increased risk of 3-year mortality in nondiabetic patients with acute first-ever ischemic stroke. Careful cardiac evaluation and treatment are essential in patients with AF and stroke.

Association between pneumonia in acute stroke stage and 3-year mortality in patients with acute first-ever ischemic stroke

The influence of pneumonia in acute stroke stage on the clinical presentation and long-term outcomes of patients with acute ischemic stroke is still controversial. We investigate the influence of pneumonia in acute stroke stage on the 3-year outcomes of patients with acute first-ever ischemic stroke. Nine-hundred and thirty-four patients with acute first-ever ischemic stroke were enrolled and had been followed for 3years. Patients were divided into two groups according to whether pneumonia occurred during acute stroke stage or not. Clinical presentations, risk factors for stroke, laboratory data, co-morbidities, and outcomes were recorded. The result showed that a total of 100 patients (10.7%) had pneumonia in acute stroke stage. The prevalence of older age, atrial fibrillation was significantly higher in patients with pneumonia in acute stroke stage. Total anterior circulation syndrome and posterior circulation syndrome occurred more frequently among patients with pneumonia in acute stroke stage (P<0.001 and P=0.009, respectively). Multivariate Cox regression revealed that pneumonia in acute stroke stage is a significant predictor of 3-year mortality (hazard ratio=6.39, 95% confidence interval=4.03-10.11, P<0.001). In conclusion, pneumonia during the acute stroke stage is associated with increased risk of 3-year mortality. Interventions to prevent pneumonia in acute stroke stage might improve ischemic stroke outcome.

Ultrasound-Guided Percutaneous Radiofrequency Lesioning When Treating Recalcitrant Plantar Fasciitis: Clinical Results

PURPOSE

We evaluated the effects of ultrasound (US)-guided percutaneous radiofrequency thermal lesioning (RTL) and the impact of obesity when treating patients with recalcitrant plantar fasciitis.

MATERIALS AND METHODS

30 consecutive patients were enrolled. The visual analog scale (VAS), American Orthopedic Foot-Ankle Society (AOFAS) Ankle-Hindfoot Score, and plantar fascia thickness measured using US were recorded at baseline and at follow-up 1, 3, 6, and 12 months after surgery under local anesthesia.

RESULTS

12 patients in the obese (BMI ≥ 30 kg/m(2)) group and 18 patients in the non-obese group. There were significant postoperative decreases in VAS scores and in fascial thickness, and an increase in the AOFAS scores (all p < 0.001). The obese group showed delayed pain and functional improvement within the first 3 months after the index procedure (p < 0.01). Significant pain reduction and functional improvement were apparent earlier (after 1 month, p < 0.001) in the non-obese group than in the obese group (after 3 months, p < 0.05). Fascia thickness was positively correlated with the VAS score and negatively correlated with the AOFAS score (both p < 0.001).

CONCLUSION

US should be regarded as a useful objective tool to guide RTL and to monitor the effectiveness of treatment. US-guided percutaneous RTL for recalcitrant PF is a minimally invasive treatment option that yields satisfactory results. Therefore, it should at least be considered before using more invasive procedures. Moreover, obesity leads to delayed improvement but does not affect overall outcome after 12 months. Plantar fascial thickness was correlated with VAS and AOFAS scores.

Sitagliptin After Ischemic Stroke in Type 2 Diabetic Patients: A Nationwide Cohort Study

The cerebrovascular safety and efficacy of sitagliptin, a dipeptidyl peptidase-4 inhibitor, in patients with type 2 diabetes mellitus (T2DM) with ischemic stroke remains uncertain. The aim of this study was to assess the efficacy and safety of sitagliptin in patients with T2DM with recent ischemic stroke. We analyzed data from the Taiwan National Health Insurance Research Database between March 1, 2009, and December 31, 2011. Ischemic stroke patients were identified from individuals with T2DM. Patients who received sitagliptin were compared with those who did not to evaluate the cardiovascular safety and efficacy of sitagliptin. The primary outcome was a composite of ischemic stroke, myocardial infarction, or cardiovascular death. A total of 5145 type 2 diabetic patients with ischemic stroke met our inclusion criteria and were followed for up to 2.83 years (mean, 1.17 years). Overall, 1715 patients (33.3%) received sitagliptin and 3430 patients (66.7%) did not. The primary composite outcome occurred in 190 patients in the sitagliptin group (11.1%) and in 370 patients in the comparison group (10.8%) (hazard ratio [HR] = 1.02; 95% confidence interval [CI], 0.85-1.21). Patients treated with sitagliptin had a similar risk of ischemic stroke, hemorrhagic stroke, and all-cause mortality with an HR of 0.95 (95% CI, 0.78-1.16, P = 0.612), 1.07 (95% CI, 0.55-2.11, P = 0.834), and 1.00 (95% CI, 0.82-1.22, P = 0.989), respectively, compared with patients not treated with sitagliptin. Treatment with sitagliptin in type 2 diabetic patients with recent ischemic stroke was not associated with increased or decreased risks of adverse cerebrovascular outcomes.

Association between renal dysfunction and 3-year mortality in patients with acute first-ever ischemic stroke

OBJECTIVE

The influence of renal dysfunction on the clinical presentation and outcomes of patients with acute ischemic stroke is still controversial. We investigate the influence of renal dysfunction on the outcomes of patients with acute first-ever ischemic stroke.

METHODS

Nine-hundred thirty-four patients with acute first-ever ischemic stroke were enrolled and followed for 3 years. Renal function was assessed using the equation of the Modification Diet for Renal Disease for estimated glomerular filtration rate (eGFR). Serum creatinine levels were obtained within 3 days of acute stroke onset. Reduced eGFR was defined as eGFR<60ml/min/1.73m(2). Clinical presentation, risk factors for stroke, laboratory data, co-morbidities, and outcomes were recorded.

RESULTS

Total 264 patients (28.3%) had a reduced eGFR. The prevalence of older age, hypertension, and atrial fibrillation was significantly higher in patients with a reduced eGFR. Total anterior circulation syndrome occurred more frequently among patients with a reduced eGFR (P=0.010). Multivariate Cox regression revealed that a reduced eGFR is a significant predictor of 3-year mortality (HR=1.67, 95% CI=1.06-2.62, P=0.026).

CONCLUSION

Reduced eGFR during the acute stroke stage is associated with increased risk of 3-year mortality. Furthermore, risk of acute complications and poor functional outcomes following discharge was significantly higher in patients with a reduced eGFR.

The impact of smoking on the severity of acute ischemic stroke

OBJECTIVES

This study investigated the impact of smoking on the initial severity of acute ischemic stroke and examined its subsequent outcome.

METHODS

Patient data was collected from the Stroke Registry in the Chang Gung Healthcare System (SRICHS). A total of 2650 patients admitted for acute ischemic stroke from January to December 2009 were included. Baseline characteristics were compared between smokers and non-smokers. Factors affecting the initial severity and the recovery from neurological deficit were examined by logistic regression analysis. The patients were further divided according to stroke mechanism for subgroup analysis.

RESULTS

The total number of smokers and non-smokers was 817 (31.9%) and 1833 (69.1%), respectively. Univariate analysis showed that smokers had lower NIHSS scores on admission than did non-smokers (P<0.001). In subgroup analysis, smokers with small-vessel occlusions frequently had higher NIHSS scores on admission than did non-smokers (P=0.001). However, smokers with cardioembolic stroke had lower NIHSS scores on admission as compared to non-smokers (P=0.024). No subgroup had smoking as a significant factor for neurological recovery during hospitalization.

CONCLUSIONS

Smoking correlated with higher NIHSS scores on admission for small-vessel occlusion. Conversely, it was associated with lower NIHSS scores on admission for cardioembolism.

Model-based segmentation of flexor tendons from magnetic resonance images of finger joints

Trigger finger is a common hand disease, causing swelling, painful popping and clicking in moving the affected finger joint. To better evaluate patients with trigger finger, segmentation of flexor tendons from magnetic resonance (MR) images of finger joints, which can offer detailed structural information of tendons to clinicians, is essential. This paper presents a novel model-based method with three stages for automatically segmenting the flexor tendons. In the first stage, a set of tendon contour models (TCMs) is initialized from the most proximal cross-sectional image via two-step ellipse estimation. Each of the TCMs is then propagated to its distally adjacent image by affine registration. The propagation is sequentially performed along the proximal-distal direction until the most distal image is reached, as the second stage of segmentation. The TCMs on each cross-sectional image are refined in the last stage with the snake deformation. MR volumes of three subjects were used to validate the segmentation accuracy. Compared with the manual results, our method showed good accuracy with small average margins of errors (within 0.5 mm) and large overlapping ratio (dice similarity coefficient above 0.8). Overall, the proposed method has great potential for morphological change assessment of flexor tendons and pulley-tendon system modeling for image guided surgery.

Effect of bilateral reaching on affected arm motor control in stroke – with and without loading on unaffected arm

PURPOSE

To investigate the effect of bilateral reaching, with/without inertial loading on the unaffected arm, on hemiparetic arm motor control in stroke.

METHODS

Twenty unilateral stroke patients were recruited. A three-dimensional optical motion capture system was used to measure the movement trajectory of the hemiparetic arm while performing three tasks: affected limb reaching forward; two-limb reaching forward; and two-limb reaching forward with inertia loading of 25% upper limb weight on the unaffected limb, respectively. Kinematical parameters were utilized to quantify the reaching performance of the affected arm.

RESULTS

No matter whether loading was applied on the unaffected arm or not, the bilateral reaching task did not significantly facilitate smoother and faster movement. Furthermore, during bilateral reaching task with/without loading on the unaffected arm, stroke patients showed slower movement, lower maximal movement velocity, feedback control dominant and discontinuous movements in the affected arm than the same task with unilateral reaching. Subjects showed the greatest active upper extremity range of motion in proximal joints during the bilateral reaching task without unaffected arm loading. The amount of trunk movement also increased during bilateral reaching either with or without loading on the unaffected arm. Patients with moderate upper extremity motor impairment performed more discontinuous movements and less active elbow range of motion during bilateral reaching tasks; however, those with mild upper extremity motor impairment performed smoother movements and demonstrated greater active elbow range of motion during bilateral reaching tasks.

CONCLUSIONS

Bilateral reaching tasks with/without loading on the unaffected arm could be considered as adding challenges during motor control training. Training with bilateral arm movements may be considered as a treatment strategy, and can be incorporated in stroke rehabilitation to facilitate greater arm active movement and improve motor control performance in the affected arm.

Effects of passivation treatments on titanium alloy with nanometric scale roughness and induced changes in fibroblast initial adhesion evaluated by a cytodetacher

Passivation treatments of titanium alloy alter not only its nanosurface characteristics of oxides and ion release but also surface roughness (Ra), and wettability as well, where nanosurface characteristics of oxides include chemistries of oxides, amphoteric-OH groups adsorbed on oxides, and oxide thickness. Consequently, the passivation treatment affects the alloy's cyto-comparability. In this study, we polish specimens to achieve nanometric scale roughness. In addition, treatment effects are evaluated for surface topology, roughness, wettability, and responses of fibroblasts consisting of MTT assay, initial adhesion strength, and morphology. The initial adhesion strength is measured using a cyto-detacher that achieves nano-Newton resolution. Results reveal that (1) the treatment effects on the percentage of Ti--OH basic groups and wettability are nearly collinear; (2) the Ra of passivated Ti-6Al-4V ranges from 1.9 to 7.4 nm; (3) the initial adhesion strength of fibroblast ranges from 58 to 143 nN, and it is negatively correlated to the Ra; (4) the passivation results in distinguishable morphologies, which further substantiate the negative correlation between cell initial adhesion force and Ra; and (5) our results fall short of confirming previous reports that found positively charged functional groups promoting fibroblast attachment and spread. Potential causes of the inconsistency are addressed.

Effects of nano-surface properties on initial osteoblast adhesion and Ca/P adsorption ability for titanium alloys

Titanium alloys (Ti6Al4V), while subjected to high temperature surface treatment, experience altered nano-surface characteristics. The effects of such surface treatments are examined, including the initial adhesion force experienced by osteoblasts, the Ca/P adsorption capability, and the nano-surface properties, including the amounts of amphoteric Ti-OH groups, surface topography, and surface roughness. The initial adhesion force is considered a quantitative indicator of cyto-compatibility in vitro. Previously, a cyto-detacher was applied in a pioneer attempt measuring the initial adhesion force of fibroblasts on a metal surface. Presently, the cyto-detacher is further applied to evaluate the initial adhesion force of osteoblasts. Results reveal that (1) titanium alloys subjected to heat treatment could promote the adsorption capability of Ca and P; (2) titanium alloys subjected to heat treatment could have higher initial osteoblast adhesion forces; (3) the adhesion strength of osteoblasts, ranging from 38.5 to 58.9 nN (nanonewtons), appears stronger for rougher surfaces. It is concluded that the heat treatment could have impacted the biocompatibility in terms of the initial osteoblast adhesion force and Ca/P adsorption capability.

A 2-D model of wheelchair propulsion

PURPOSE

To illustrate the potential benefits of kinetic and kinematic models in the exploration of biomechanical studies as illustrated using a simple 2-D static optimization model of wheelchair propulsion.

METHOD

A four-bar linkage analysis was used to determine sagittal plane motion through the range of wheelchair propulsion. Using anthropometric measures of wheelchair users, this analysis determined the angles of shoulder and elbow flexion/extension at a given point in the propulsion cycle. Maximal strength inputs for the model were collected from isokinetic measurements of shoulder and elbow moments. The torque inputs were given as functions of sagittal plane joint angles. Through selection of appropriate model performance criteria, optimization techniques determined shoulder and elbow torque contributions throughout the propulsion cycle. Variations in the model parameters of anterior-posterior (AP) seat position and handrim size went used to show potential of model to evaluate wheelchair configuration using the performance criteria of propulsive moment (Mo) and efficiency as defined by fractional effective force (FEF).

RESULTS

The model was able to predict the magnitude and direction of force applied to the handrim from shoulder and elbow moments. These joint moments may be examined along with the generated wheelchair axle propulsion moment. While the model showed no significant changes in either Mo or FEF for AP seat changes, an increase in handrim size was shown to increase FEF.

CONCLUSIONS

This model was able to simulate wheelchair propulsion and allow for performance analyses. The open nature of the model allowed for tweaking of the kinematic inputs to examine the sensitivity of such factors as seat position and handrim size in wheelchair propulsion. Strength inputs to the model may also be altered to study the potential effects of strength training or muscle weakness.

Elbow load with various forearm positions during one-handed pushup exercise

This is the first study of the one-handed pushup, and tries to show the effects of forearm rotations. Previous studies of elbow loading have focused on passive loading and small loads, because data from large loads during active exercise is not easy to obtain. In order to investigate the biomechanical impact of hand position on the elbow and the potential trauma mechanisms of outstretched elbow, joint loading across the elbow was analyzed for three forearm rotational positions, neutral, 90 degrees internal rotation and 90 degrees external rotation. Both kinematic and kinetic data were collected from eight volunteers by the Motion Analysis System and a Kistler Force Plate. Statistical analysis of the data delineates the relationship between elbow joint load and hand rotational position during one-handed pushup, and also provides useful biomechanical information for this challenging exercise. The axial and valgus stresses and forces are the major concerns. The peak axial forces exerted on the elbow joint averaged 65 % of the body weight when the hand position was neutral, and was significantly reduced with the hand rotated either internally or externally. The peak valgus shear force with the hand externally rotated was 50 % greater than the other two positions. Thus, outward rotation of the hand is a stressful position that should be avoided during one-handed pushup exercise or forward falls with outstretched hands in order to reduce the risk of elbow injuries.

Effect of elbow flexion on upper extremity impact forces during a fall

OBJECTIVE

The overall objectives are to develop a biomechanical model for a simulated fall with outstretched hand.

DESIGN

Cross-sectional study involving young healthy volunteers in a university research laboratory setting.

BACKGROUND

Little is known about the factors which influence fracture risk during a fall on outstretched hand.

METHODS

A group of 11 male subjects volunteered for this investigation. A set of eight reflective markers was placed bilaterally on selected anatomic landmarks. Subjects were suspended with both elbows extended and wrists dorsiflexed, preparing to impact the ground and force plates from two different fall heights: 3 and 6 cm. Two different postures for the elbows were employed. In the elbow extension experiment, the elbows were extended at all times. In the elbow flexion experiment, the elbows were extended at impact, but then flexed immediately, as though in the initial downward phase of a push-up exercise.

RESULT

Increasing the fall height significantly increased the upper extremity axial forces by 10% and 5%. No significantly different differences were found in the axial forces applied to the wrist, elbow or shoulder between the elbow flexion and elbow extension trials, but the elbow mediolateral shear force was 68% larger (P=0.002) in the extension trials.

CONCLUSIONS

Performing an elbow flexion movement at impact reduces the first peak impact force value and postpones the maximum peak value. Although changing the fall arrest strategy from elbow extension to elbow flexion did not affect the peak impact force on the hand, it did require substantially greater elbow and shoulder muscle strengths.

RELEVANCE

This paper yields insights into how the physical demands of arresting mild falls may relate to upper extremity muscle capacity, joint dislocation and bony fracture.

Gait analysis after total hip arthroplasty with leg-length equalization in women with unilateral congenital complete dislocation of the hip--comparison with untreated patients

Patients with Crowe Type-IV congenital dislocation of the hip (CDH) show significant clinical improvement after total hip arthroplasty (THA) because this surgery greatly reduces pain. Concomitant leg-length equalization in unilateral patients--a controversial procedure--theoretically should significantly improve these patients' ability to walk efficiently and comfortably. To understand the impact of leg-length equalization on these patients, we compared their gait parameters with those of untreated patients without pain but with leg-length discrepancy. Using a motion analysis system, three force platforms and computer calculation, the gait parameters during level walking of 22 women with unilateral Crowe Type-IV CDH were studied at an average of 58 months (27-98 months) following a successful cementless THA. The socket was placed in the best bone stock, which was close to the level of the true acetabulum. The leg-length discrepancy was equalized to within 2 cm in all patients. The Harris hip score averaged 94.8 (range, 88-100) at the time of the study. Nine women with untreated unilateral Crowe Type-IV CDH without major pain but with an average leg-length discrepancy of 4.7 cm (range, 2.5-6 cm) were also studied for comparison. The treated subjects (Group 1; THA and leg-length equalization) walked faster and had gait parameters with better bilateral symmetry than the untreated subjects (Group 2). We concluded that leg-length equalization in addition to THA in patients with unilateral Crowe Type-IV CDH significantly improves gait symmetry and efficiency.

Vestibular system in performance of standing balance of children and young adults under altered sensory conditions

Inputs from the visual, somatosensory and vestibular systems must be integrated efficiently to activate appropriate motor responses in maintaining optimal balance. This study examined the standing balance of 17 children (7 to 10 years old) and 17 young adults (19 to 23 years old) as a function of sensory organization, sensory system efficiency, and postural strategy adopted. Tests of standing balance were administered under six sensory conditions created by simultaneous alteration of the visual (full, occluded, or sway-referenced) and the somatosensory inputs (fixed-foot or compliant-foot support). The sway area and the sway amplitude of the center of pressure were measured and analyzed. Three findings are notable. The function of sensory organization for balance control was poorer for the children than the young adults. The functional efficiency of the somatosensory and the visual systems of children have developed to the young adult level, but that of the vestibular system has not. There was no difference between children and young adults in hip control, but there was in ankle control when the vestibular input was the only reliable source of sensory input. These results suggest that the functional efficiency of the vestibular system in children 7 to 10 years of age may still be developing. This may account for their poorer function of sensory organization and lower performance of standing balance.

Elbow load during pushup at various forearm rotations

OBJECTIVE

Elbow joint loading was evaluated during pushup exercises at various forearm rotations.

DESIGN

Subjects were asked to perform pushup in various forearm rotations: neutral, 90 degrees internal rotation, and 90 degrees external rotation.

BACKGROUND

Training with pushup exercise is good for the muscles and joints of the upper extremities. However, excessive shear forces on the elbow might lead to injuries to either normal trainees or to handicapped people, especially for those who rely on elbow prosthesis.

METHODS

The kinematics and kinetics of the elbow joint were investigated under various forearm rotations.

RESULTS

The loading biomechanics of the elbow joint differed with various forearm rotations. It was noted that greater posterior and varus forces of the elbow are encountered with internal rotation of the hand position and, consequently, full forearm pronation.

CONCLUSIONS

Pushup with hands in internally rotated position should be prevented so as to avoid excessive shear forces or moments.

RELEVANCE

Knowledge of elbow kinematics and kinetics may be helpful in preventing injuries by reducing the elbow shear force with changes of forearm rotation.

Sit-to-stand at different periods of pregnancy

OBJECTIVE

This study was performed to determine the biomechanics of chair rising by pregnant women.

DESIGN

Relative body joint position and ground reaction forces were measured by a motion analysis system and one force plate.

BACKGROUND

Physiological and psychological changes during pregnancy impose postural demands and limit the performance of daily living activities such as rising from sitting to standing position.

METHODS

Twenty-four pregnant women, divided into three groups, were studied performing sit-to-stand transition from an armless and adjustable chair. By kinematic and kinetic analysis, the angles and moments of hip, knee and ankle joints were investigated.

RESULTS

The chair height has great influence on knee joint and hip joint moments, but less on ankle joints. In the third trimester for all chair heights, because of a marked increase in abdominal depth, the maximum hip moment is significantly less than that in first trimester, while the maximum knee moment is significantly larger. Pregnant women in third trimester produced larger knee moment during sit-to-stand transition from lower chair height.

CONCLUSIONS

The mechanism of sit-to-stand is affected by the physical changes of pregnant women at different periods of pregnancy, e.g. increased loading of knee joint and decreased hip joint moment, especially in the last trimester period of pregnancy.

Potential of the genetic algorithm neural network in the assessment of gait patterns in ankle arthrodesis

The aim of this study was to develop an empirical model of parameter-based gait data, based on an artificial neural network and a genetic algorithm, for the assessment of patients after ankle arthrodesis. Ground reaction force vectors were measured by force platforms during level walking. Nine force parameters expressed in percentage of body weight and their chronologic incidence of occurrence expressed in percentage of stance phase period were used in modeling. Ten healthy persons and ten patients who had solid arthrodesis of the ankle were recruited in this study for developing the model. By applying the genetic algorithm neural network, the percentage of correct classification was 98.8% and the subset of discriminant parameters was be reduced to 9 out of 18. These key parameters were mainly related to the loading response and propulsive phase. This indicates that there was a reduction in the abilities in cushion impact and push off in the patients after ankle arthrodesis. Finally, the relative distance (Dr) was defined in this study and used in two new patients' examinations to demonstrate its clinical utility.

Gait analysis and energy consumption of below-knee amputees wearing three different prosthetic feet

This study scientifically measures the dynamic gait characteristics and energy consumption of 16 male below-knee amputees, eight vascular and eight traumatic, while wearing solid ankle cushion heel (SACH), single axis and multiple axis prosthetic feet via six-camera motion analysis, metabolic measurement cart and heavy-duty treadmill. Subjective results are additionally determined via questionnaire after testing. Motion analysis showed statistically significant differences at P<0.05 between the SACH, single axis and multiple axis foot in the velocity, cadence, stride length and single limb stance. Significant differences were found in energy consumption between the traumatic and vascular groups, and significant changes in walking under different speeds and different inclines. Results provide quantitative and qualitative information about the dynamic performance of the various feet, which can be helpful in prescribing the optimal prosthetic foot for individual amputees.

Common abnormal kinetic patterns of the knee in gait in spastic diplegia of cerebral palsy

We studied the kinetic characteristics of the knee in patients with spastic diplegia. Twenty three children with spastic diplegia were recruited and had their 46 limbs categorised into the following four groups: jump (n=7), crouch (n=8), recurvatum (n=14) and mild (n=17). In the crouch pattern, the patients usually had a larger and longer lasting internal knee extensor moments in stance suggesting that rectus femoris had a relatively high activation. In the recurvatum pattern, the internal knee flexor moment was large and long lasting in stance. The biceps femoris showed less activity on EMG although the knee flexor moment was large and we concluded that the soft tissue behind the knee joint provided this flexor moment. In the jump knee pattern there was abnormal power generation at the knee and ankle joints in initial stance, which did not contribute to normal progression but aided upward body motion. In the mild group the kinetic data was similar to that seen in normal children. Knowledge of kinetic patterns in these patients may help in their subsequent management.

Prediction of muscle force involved in shoulder internal rotation

The estimation of shoulder muscle force is important to understand the mechanism of rotator cuff injury. In general, mean parameter values are used as input for computational models. However, anatomic and biomechanical parameters vary widely among people. The purpose of this study was to evaluate shoulder muscle forces predicted by an electromyography-driven muscle model given neuromuscular parameters generated by Monte Carlo simulation. Normal distributions were used to model muscle moment arms; electromyographic and muscle physiological cross-sectional area data were modeled with log-normal distributions. Eight muscles were included in the model. Muscle force and joint moment were predicted on the basis of the simulated parameters. The results showed that the subscapularis and pectoralis major were substantial actuators for shoulder internal rotation. During maximum voluntary contraction the median of the muscle forces of the subscapularis and the pectoralis major were 1030 N and 462 N, respectively. This study demonstrated that the Monte Carlo method could be used for muscle force prediction by integrating population variability of physiological parameter into a biomechanical muscle model.

Foot progression angle and ankle joint complex in preschool children

OBJECTIVE

The influence of foot progression angle on the ankle joint and the effects on gait patterns and mechanisms in skeletally normal preschool children was investigated.

DESIGN

Kinematics and kinetics of the ankle joint were analyzed for preschool children who were skeletally normal but walked with different foot progression angle.

BACKGROUND

The most frequent reasons for preschool children to be brought to a paediatric orthopaedic clinic are toe-in and toe-out. Without understanding the biological and biomechanical implications, treatment for these problems can be very confusing.

METHODS

Gait analysis was performed in 86 skeletally normal preschool children. Children were grouped according to their foot progression angles. Analysis of the kinematics and kinetics of the ankle joint was intended to elucidate the gait mechanism.

RESULTS

Children with different foot progression angles had distinctive patterns of spatio-temporal parameters, ground reaction force, joint angle, moment, power, and mechanical work of the ankle joints. The differences were organized and explained as different walking patterns and tactics.

CONCLUSIONS

Skeletally normal preschool children with excessive toe-in or toe-out foot progression angles are not necessarily in some diseased status. They were instead related to different walking patterns. Aggressive treatment for these problems is not recommended.RelevanceThese results suggest that toe-in and toe-out are related to walking speed which has distinct influences on the kinematics and kinetics of the ankle joint. Though the observed problems were seemingly only in the transverse plane, they are in fact three-dimensional and have a mutually close relationship. The findings could be linked to the promptness of muscle response and the habits of walking in preschool children. Better understanding of possible mechanisms will help parents and paediatricians decide on the most appropriate treatment for these children.

Comparison of two-dimensional and three-dimensional techniques for determination of facial motion--absolute movement in a local face frame

BACKGROUND AND PURPOSE

Few studies have used motion analysis in the study of facial animation. A facial animation model using an expert vision motion analysis system was developed in this study to quantitatively evaluate absolute movement during five facial animations.

METHODS

Skin markers were adhered to the face of each subject at 16 anatomic landmarks selected to represent the functional movement of the facial muscles. Three of the 16 skin markers were used to establish a local face frame with the origin in the mid-point of the face. All of the coordinates measured in the laboratory frame were rotated and translated to the local face frame for analysis. The trajectory of the facial markers was evaluated from the local face frame when comparing two-dimensional (2-D) displacement of skin markers (frontal plane) with three-dimensional (3-D) values by paired Student's t-test.

RESULTS

Although the correlation of 2-D and 3-D displacements of skin markers was high (r > 0.69), the differences between 2-D and 3-D motion were significant (p < 0.001). The 2-D displacement of skin markers underestimated the 3-D facial animation in each marker and animation. There were no significant differences in the movement of both mouth angles or of the eyes. Thirty repeated measurements of a subject revealed good concentration in 3-D displacement, velocity, and angle of movement in smiling. The measurement error was less than 0.06 mm. The normative displacement of individual anatomic landmarks was evaluated to avoid size differences of individual faces.

CONCLUSIONS

We suggest that the expert vision motion analysis technique is feasible for quantitative evaluation of absolute facial movement and would be useful for further clinical evaluation of patients with facial palsy.

The use of the motion analysis system for evaluation of loss of movement in the finger

We have used the motion analysis system to measure loss of finger movement after injury. The motion analysis system can provide information about the dynamic angular changes of each finger joint and the fingertip motion area for the injured finger. The latter can be used to calculate the percentage of fingertip motion area preserved. A stiff finger may show limited fingertip motion area with the finger joints tending to flex and extend together.

Gait analysis after ankle arthrodesis

The purpose of this study was to employ a computerized motion analysis system to identify the effect of ankle arthrodesis on the three-dimensional kinematic behavior of the rear and fore foot during level walking. A three-segment rigid body model was used to describe the motion of the foot and ankle. The results demonstrated that sagittal plane motion of the hindfoot was significantly decreased in the foot of patients having had ankle arthrodesis compared to normal subjects. The kinematic data indicated a generalized stiffness of the hindfoot on the involved foot in the sagittal plane. Sagittal plane movement in the forefoot and transverse plane movements in the hindfoot and forefoot increased in patients compared to controls.

Potential of the back propagation neural network in the assessment of gait patterns in ankle arthrodesis

OBJECTIVE

The purpose of this study was to recognize gait pattern in ankle arthrodesis by using a neural network trained with time domain input and compare the performance of the neural network with the statistical method.

DESIGN

Three-layered feed-forward back propagation neural network and a statistical method were used to classify gait patterns of patients with ankle arthrodesis and normal subjects.

BACKGROUND

Although backpropagation neural networks are very efficient in many pattern recognition tasks, they have not been used for gait pattern recognition of ankle arthrodesis.

METHODS

A total of eighteen parameters measured by force platforms, including nine force parameters and their chronologic incidence of occurrence, were used to classify gait patterns.

RESULTS

The results showed that the neural network model was able to classify subjects with recognition rates up to 95.8%. In contrast, the statistical method was only able to classify the subjects with recognition rates of 91.5%.

CONCLUSIONS

The backpropagation neural network method has better accuracy than the statistical method in discriminating subjects and the time domain features carry important prognostic information.

RELEVANCE

It is important to be able to quantify the changes in gait pattern after arthrodesis to understand the clinical implications of arthrodesis.

Design and testing of a genetic algorithm neural network in the assessment of gait patterns

It is important to be able to quantify changes in gait pattern accurately in order to understand the clinical implications of surgery or rehabilitation. Although supervised feed-forward backpropagation neural networks are very efficient in many pattern-recognition tasks, the genetic algorithm neural network (GANN), which can search in some appropriate space, has not been used previously for gait-pattern recognition. This study discusses how to use the GANN approach in gait-pattern recognition, and evaluates the complexity and training strategy of the particular classification problem. Both the GANN and a traditional artificial neural network (ANN) were used to classify the gait patterns of patients with ankle arthrodesis and normal subjects. The GANN model was able to classify subjects with recognition rates of up to 98.7%. In contrast, the ANN trained by using all possible predictor variables was only able to classify the subjects with recognition rates of 89.7%. It is suggested that the GANN model is more suitable to exploit the patient's gait pattern. The value of the neuron output can be used as an index of the difference from normal. By this means, all pathological gait patterns may be presented quantitatively.

Optimum length of muscle contraction

OBJECTIVE

The purpose of this study was to develop a mathematical method to determine optimum muscle length and muscle stress based on the measurable physiological and biomechanical data.

DESIGN

The values of optimum muscle length and muscle stress are investigated.

BACKGROUND

Understanding the characteristics of muscle function in vivo is important for assisting the design of the tendon transfer and other rehabilitation procedures. In vivo determination of the physiological and anatomical parameters of muscle contraction is difficult but not impossible. Optimum muscle length and muscle stresses are important parameters for understanding muscle function.

METHODS

A Cybex dynamometer was used to measure isometric elbow flexion torque in eight different joint positions in seven subjects. Then the optimization method was used to determine optimum muscle length and muscle stress of three major elbow flexors, the biceps brachii, the brachialis, and the brachioradialis based on the model and joint torque data.

RESULTS

The calculated muscle stress for each subject was on average 109 N/cm(2), while the optimum muscle length for the biceps brachii, the brachialis, and the brachioradialis was on average 14.05, 6.53, 17.24 cm, respectively. The joint angles corresponding to these optimum muscle lengths are 110 degrees, 100 degrees and 50 degrees of elbow flexion, respectively.

CONCLUSIONS

Optimum muscle length and muscle stress can be properly predicted using an analytical mathematical model along with an experimentally measured joint torque.

RELEVANCE

The estimate of optimum muscle length is important for muscle modeling and tendon transfer surgery by taking advantage of length-tension relationship of individual muscles.

Performance of static standing balance in children with spastic diplegic cerebral palsy under altered sensory environments

Seven children with spastic diplegic cerebral palsy and 14 age- and gender-matched nondisabled children participated in the present study for an investigation and comparison of their static standing balance under altered sensory environments. The type of visual input (full, occluded, or sway referenced vision) and the type of somatosensory input (fixed or compliant foot support) were varied factorially to give six sensory environments. Each participant was tested barefooted for 30 s under all six conditions. A force platform collected the ground reaction force, from which standing balance was calculated as the sway area of the center of pressure. The results showed that when somatosensory information was reliable (fixed foot support), there was no significant difference in stance stability between the children with spastic diplegic cerebral palsy and their matched controls, and both types of children were equally affected by the type of visual input. However, when somatosensory information was unreliable (compliant foot support), the difference in stance stability between the children with spastic diplegic cerebral palsy and their matched controls was significantly greater when the visual input was deprived (occluded) or unreliable (sway referenced) than when it was reliable. These results suggest that the children with spastic diplegic cerebral palsy may have difficulties in resolving intersensory conflicts for maintenance of standing balance, or the demands of motor control in sensory conflict conditions outweigh the motor ability of children with spastic diplegic cerebral palsy.

Hemiplegic gait of stroke patients: the effect of using a cane

OBJECTIVE

To assess the effects of cane use on the hemiplegic gait of stroke patients, focusing on the temporal, spatial, and kinematic variables.

DESIGN

Case-control study comparing the effect of walking with and without a cane using a six-camera computerized motion analysis system.

SETTING

Stroke clinic of a tertiary care hospital.

PARTICIPANTS

Fifteen ambulatory stroke patients were analyzed, including 10 men and 5 women (mean age, 56.9 years; mean time since stroke, 9.8 weeks). Nine age-matched healthy elderly subjects were recruited as a control group.

RESULTS

Stroke patients walking with a cane showed significantly increased stride period, stride length, and affected side step length, as well as decreased cadence and step width (p < .05) in comparison with those who walked without a cane. There were no significant differences in the gait phases and the five gait events of hemiplegic gait walking with or without a cane. Cane use thus may have more effect on spatial variables than on temporal variables. The affected-side kinematics of hemiplegic gait with a cane showed increased pelvic obliquity, hip abduction, and ankle eversion during terminal stance phase; increased hip extension, knee extension, and ankle plantar-flexion during preswing phase; and increased hip adduction, knee flexion, and ankle dorsiflexion during swing phase as compared with hemiplegic gait without a cane. A cane thus improved the hemiplegic gait by assisting the affected limb to smoothly shift the center of body mass toward the sound limb and to enhance push off during preswing phase. It also improved circumduction gait during swing phase.

CONCLUSION

Stroke patients walking with a cane demonstrated more normal spatial variables and joint motion than did those without a cane.

The motion analysis system and goniometry of the finger joints

The application of a video-based motion analysis system for goniometry of finger joints during measurement of the fingertip motion area has been assessed. The results indicate that the motion analysis system is reliable for angular measurements of finger joints that are comparable with those obtained by conventional goniometer. The advantages of using the motion analysis system is that it can record and show the changes in angle of all finger joints continuously during finger motion.

An instrumented wheel for kinetic analysis of wheelchair propulsion

An instrumented wheel system for three-dimensional kinetic analysis of upper extremity during wheelchair propulsion has been designed and validated. This system allows the direct measurements of three-dimensional dynamic forces and moments on the handrim during wheelchair propulsion in a laboratory setting as well as in the field. Static loading tests showed a high linearity and little drift (coefficient of determination, r2 > 0.999). Under dynamic loading, the instrumented wheel provided the well-matched measurement forces and moments with the predicted values from the inverse dynamic method using video-based kinematic data (correlation coefficient, p > 0.97). The three-dimensional handrim forces and moments during wheelchair propulsion by a non-disabled subject were demonstrated.

The motion analysis system and the fingertip motion area. Normal values in young adults

The reliability of the motion analysis system and the normal value of the fingertip motion area have been studied in young adults. The results indicate that the motion analysis system is a reliable tool for the evaluation of fingertip motion. It was found that the fingertip motion area in young adults has a linear correlation with the square of the finger length. Therefore, the normal value of the fingertip motion area can be calculated from the finger length.

Gait analysis of adult patients with complete congenital dislocation of the hip

Comprehensive gait analysis is valuable in understanding the performance of patients with lower limb disorders. The gait pattern of adult patients with untreated congenital dislocation of the hip (CDH) has not yet been reported. We studied the gait pattern in nine women (mean age 31.4 years) with Crows group IV CDH. Six had unilateral and three had bilateral involvement. They were not treated during childhood and had no pain at the time of study. A control group comprised 15 normal female subjects of the same age group. Gait was studied using a motion-analysis system, force plateforms, and computer calculation during level walking. Common abnormal gait patterns seen in patients with both unilateral and bilateral CDH were slower walking velocity, which was due to a shorter stride length, less forward tilting of the pelvis, insufficient flexion, and excessive internal rotation of the hips. The patients with unilateral CDH had a shorter step length, lower pelvis, a lateral shift of the ground reaction force, decreased maximum adduction moments of the hip and knee on the diseased side, and increased maximum adduction moments of the hip and knee on the unaffected side. This asymmetry may have been due to leg length inequality. Thus, correlation of the leg length discrepancy may be important for unilateral CDH patients in improving their gait.

The motion analysis system and the maximal area of fingertip motion. A preliminary report

We have used the motion analysis system to evaluate the maximal area of fingertip motion. Some modification in setting the cameras and use of a smaller marker is required. In this series, 58 examinations have been accomplished on 28 fingers with various traumatic injuries. The closed curve derived from the motion analysis system and the area calculated from it were easier to interpret and could be compared in serial examinations. A high linear correlation between the fingertip motion area and total active motion was found. The computer-aided motion analysis system complements the traditional methods of assessing an injured finger.

Flexion-extension rhythm in the lumbosacral spine

STUDY DESIGN AND OBJECTIVES

This study was conducted to depict the qualitative and quantitative changes of intervertebral rotation and translation from L1-L2 to L5-S1 during flexion, standing, and extension using dynamic lumbosacral radiographs.

METHODS

A radiopaque ruler was placed on the back of each subject for the normalization of translational value. Eighty-nine volunteers were examined.

RESULTS

From extension to flexion, all of the intervertebral rotations approached 0 degree from the lordotic position; the translations changed from slightly retro-listhetic to zero displacement. Using L3-L4 as a baseline for calculating the intervertebral differences in flexion, all of the rotational differences were less than 1.5 degrees, except at L5-S1, which remained 5 degrees. The mean translational difference was less than 0.6 mm, except at L5-S1, where it remained 1.5 mm.

CONCLUSIONS

The amount of total flexibility was level-dependent and its frequency distribution is important. Qualitative rhythmic changes from extension to flexion and quantitative values of intervertebral difference in flexion help define the normal flexibility more accurately.

Significance of acceleration period in a dynamic strength testing study

The acceleration period that occurs during isokinetic tests may provide valuable information regarding neuromuscular readiness to produce maximal contraction. The purpose of this study was to collect the normative data of acceleration time during isokinetic knee testing, to calculate the acceleration work (Wacc), and to determine the errors (ERexp, ERwork, ERpower) due to ignoring Wacc during explosiveness, total work, and average power measurements. Seven male and 13 female subjects attended the test by using the Cybex 325 system and electronic stroboscope machine for 10 testing speeds (30-300 degrees/sec). A three-way ANOVA was used to assess gender, direction, and speed factors on acceleration time, Wacc, and errors. The results indicated that acceleration time was significantly affected by speed and direction; Wacc and ERexp by speed, direction, and gender; and ERwork and ERpower by speed and gender. The errors appeared to increase when testing the female subjects, during the knee flexion test, or when speed increased. To increase validity in clinical testing, it is important to consider the acceleration phase effect, especially in higher velocity isokinetic testing or for weaker muscle groups.

Lumbosacral kinematics in the sagittal plane: a radiographic study in vivo

Lateral functional radiographs of flexion and extension using Putto's method were examined in 89 normal subjects. A specially-designed radiopaque ruler was placed on each film for calibration. A computer-assisted method was used for digitization and analysis. There were weak negative correlations between age and range of motion, especially at the L4-L5 level (r = 0.437). No significant correlation was noted between age and translation. For flexion-extension rotation, although large variations may limit its usefulness in judging instability in some clinical settings, the data still provide a good diagnostic basis. For translation changes, 2 mm is regarded as acceptable in most cases at levels from L1 to L5, but not at the level of L5-S1 where the average translation change was only 0.4 mm. The differences in the absolute translation value among different positions were not statistically significant (p = 0.064).