Observation of Events with an Energetic Forward Neutron in Deep Inelastic Scattering at HERA

In deep inelastic neutral current scattering of positrons and protons at the center of mass energy of 300 GeV, we observe, with the ZEUS detector, events with a high energy neutron produced at very small scattering angles with respect to the proton direction. The events constitute a fixed fraction of the deep inelastic, neutral current event sample independent of Bjorken x and Q2 in the range 3 · 10-4 \u3c xBJ \u3c 6 · 10-3 and 10 \u3c Q2 \u3c 100 GeV2

Analysis of 3-D Ultrasound of Calf Muscle Geometry in Children: Growth, Spasticity, Mechanisms and Treatment

Becher, J.G. [Promotor]Huijing, P.A.J.B.M. [Promotor]Jaspers, R.T. [Copromotor]Harlaar, J. [Copromotor

Movement within foot and ankle joint in children with spastic cerebral palsy: a 3-dimensional ultrasound analysis of medial gastrocnemius length with correction for effects of foot deformation

Background: In spastic cerebral palsy (SCP), a limited range of motion of the foot (ROM), limits gait and other activities. Assessment of this limitation of ROM and knowledge of active mechanisms is of crucial importance for clinical treatment. Methods. For a comparison between spastic cerebral palsy (SCP) children and typically developing children (TD), medial gastrocnemius muscle-tendon complex length was assessed using 3-D ultrasound imaging techniques, while exerting externally standardized moments via a hand-held dynamometer. Exemplary X-ray imaging of ankle and foot was used to confirm possible TD-SCP differences in foot deformation. Results: SCP and TD did not differ in normalized level of excitation (EMG) of muscles studied. For given moments exerted in SCP, foot plate angles were all more towards plantar flexion than in TD. However, foot plate angle proved to be an invalid estimator of talocrural joint angle, since at equal foot plate angles, GM muscle-tendon complex was shorter in SCP (corresponding to an equivalent of 1 cm). A substantial difference remained even after normalizing for individual differences in tibia length. X-ray imaging of ankle and foot of one SCP child and two typically developed adults, confirmed that in SCP that of total footplate angle changes (0-4 Nm: 15°), the contribution of foot deformation to changes in foot plate angle (8) were as big as the contribution of dorsal flexion at the talocrural joint (7°). In typically developed individuals there were relatively smaller contributions (10 -11%) by foot deformation to changes in foot plate angle, indicating that the contribution of talocrural angle changes was most important.Using a new estimate for position at the talocrural joint (the difference between GM muscle-tendon complex length and tibia length, GM relative length) removed this effect, thus allowing more fair comparison of SCP and TD data. On the basis of analysis of foot plate angle and GM relative length as a function of externally applied moments, it is concluded that foot plate angle measurements underestimate angular changes at the talocrural joint when moving in dorsal flexion direction and overestimate them when moving in plantar flexion direction, with concomitant effects on triceps surae lengths. Conclusions: In SCP children diagnosed with decreased dorsal ROM of the ankle joint, the commonly used measure (i.e. range of foot plate angle), is not a good estimate of rotation at the talocrural joint. since a sizable part of the movement of the foot (or foot plate) derives from internal deformation of the foot. © 2013 Huijing et al.; licensee BioMed Central Ltd

Reproducibility of hand-held ankle dynamometry to measure altered ankle moment-angle characteristics in children with spastic cerebral palsy

Background: In children with spastic cerebral palsy, the range of motion of the ankle joint is often limited. Measurement of range of motion may be hampered by a non-rigid foot deformity. We constructed a hand-held instrument which allows measurements of static ankle angle and moment in children with cerebral palsy while correcting for foot deformity. This study aimed to test the reproducibility of the instrument and to use it for measuring ankle moment-angle characteristics in individual children who are typically developing and children with cerebral palsy. Methods: Ankle angles and moments were measured at five standardized positions in ten children who are typically developing and ten children with cerebral palsy. The intraclass correlation coefficient was calculated for test-retest reliability. For precision, the standard error of measurement and smallest detectable difference were determined. The ankle range of motion and the slope of the moment-angle curve were determined, both towards plantar flexion and dorsiflexion. Findings: The reproducibility study revealed a high reliability of the dynamometer at 5 repetitions (> 0.97). Precision lies within 5° for angle measurements and within 0.2 Nm for moment measurements. In the children with cerebral palsy, the range of motion towards dorsiflexion was 18° lower and the slope of the moment-angle curve towards dorsiflexion was substantially higher. Interpretation: We developed a hand-held dynamometer which allows reliable and precise measurements of static ankle angle and moment in children with cerebral palsy. The hand-held dynamometer allows corrections of foot deformities and is qualified to reproducibly evaluate moment-angle characteristics in a clinical context. © 2010 Elsevier B.V. All rights reserved

Mid-term effect of total knee arthroplasty with and without tourniquet use on prosthesis survival, complications and functional outcome: A prospective cohort study of 511 total knee arthroplasties

Background: A tourniquet is often used to create a bloodless surgical field during total knee arthroplasty (TKA). It is still debated whether tourniquet use improves durability of cemented implant fixation and thereby prosthesis survival. Some studies showed tourniquet application has a negative impact on post-operative wound healing, pain and function, whilst other publications contradict this. However, no previous studies evaluated the effect of tourniquet use on prosthesis survival and mid-term functional outcome specifically.Methods: In this longitudinal observational cohort study 115 patients (116 knees) undergoing TKA without tourniquet use were compared with 374 patients (395 knees) with a tourniquet. Prosthesis survival, revision risks and complications were analysed through chart review after a mean follow-up period of 5.3 years. Additionally, patient reported outcome measures regarding knee functionality and health status (PROMs; KOOS, OKS, EQ-5D, SF-12) were collected prospectively.Results: Both groups had an equal overall re-operation rate of 4.3% and showed similar revision rates for aseptic loosening as well as for other causes. In the tourniquet group a higher complication rate (14.7% vs 10.3%) was observed. The majority was urinary retention requiring bladder catheterization. Both groups showed comparable, improved post-operative functional results compared to the pre-operative state for all PROMs at all time points.Conclusions: In this study TKA without tourniquet use yielded similar mid-term results as TKA with tourniquet use with regard to prosthesis survival, reoperations, complications, knee functionality and health status.(c) 2022 Elsevier B.V. All rights reserved

Anatomical information is needed in ultrasound imaging of muscle to avoid potentially substantial errors in measurement of muscle geometry

This study validates two-dimensional (2D) ultrasound measurements of muscle geometry of the human medial gastrocnemius (GM) and investigates effects of probe orientation on errors in these measurements. Ultrasound scans of GM muscle belly were made both on human cadavers (n = 4) and on subjects in vivo (n = 5). For half of the cadavers, ultrasound scans obtained according to commonly applied criteria of probe orientation deviated 15° from the true fascicle plane. This resulted in errors of fascicle length and fascicle angle up to 14% and 23%, respectively. Fascicle-like structures were detectable over a wide range of probe tilt and rotation angles, but they did not always represent true fascicles. Errors of measurement were either linear or quadratic functions of tilt angle. Similar results were found in vivo. Therefore, we conclude that similar errors are likely to occur for in vivo measurements. For all cadavers, at the distal end of GM, the true fascicle plane was shown to be perpendicular to the distal aponeurosis. Using transverse images of GM to detect the curvature of the deep aponeurosis at the distal end of the muscle belly is a simple strategy to help identify the fascicle plane. For subsequent longitudinal imaging, probe alignment within this plane will help minimize measurement errors of fascicle length, fascicle angle, and muscle thickness. © 2009 Wiley Periodicals, Inc

Fluoroscopic and radiostereometric analysis of a bicruciate- retaining versus a posterior cruciate- retaining total knee arthroplasty: a randomized controlled trial

Aims The aim of this study was to compare a bicruciate-retaining (BCR) total knee arthro-plasty (TKA) with a posterior cruciate-retaining (CR) TKA design in terms of kinemat-ics, measured using fluoroscopy and stability as micromotion using radiostereometric analysis (RSA).Methods A total of 40 patients with end- stage osteoarthritis were included in this randomized controlled trial. All patients performed a step -up and lunge task in front of a monoplane fluoroscope one year postoperatively. Femorotibial contact point (CP) locations were deter- mined at every flexion angle and compared between the groups. RSA images were taken at baseline, six weeks, three, six, 12, and 24 months postoperatively. Clinical and functional outcomes were compared postoperatively for two years.Results The BCR- TKA demonstrated a kinematic pattern comparable to the natural knee's screw-home mechanism in the step -up task. In the lunge task, the medial CP of the BCR- TKA was more anterior in the early flexion phase, while laterally the CP was more posterior during the entire movement cycle. The BCR- TKA group showed higher tibial migration. No differ- ences were found for the clinical and functional outcomes.Conclusion The BCR- TKA shows a different kinematic pattern in early flexion/late extension compared to the CR- TKA. The difference between both implants is mostly visible in the flexion phase in which the anterior cruciate ligament is effective; however, both designs fail to fully rep- licate the motion of a natural knee. The higher migration of the BCR- TKA was concerning and highlights the importance of longer follow- up.Orthopaedics, Trauma Surgery and Rehabilitatio

Cochlear Implants or Hearing Aids: Speech Perception, Language, and Executive Function Outcomes.

OBJECTIVES: We aimed to determine whether children with severe hearing loss (HL) who use hearing aids (HAs) may experience added value in the perception of speech, language development, and executive function (EF) compared to children who are hard of hearing (HH) or children who are deaf and who use cochlear implants (CIs) and would benefit from CIs over HAs. The results contribute to the ongoing debate concerning CI criteria. We addressed the following research question to achieve this aim: Do children who are HH or deaf with CIs perform better than children with severe HL with HAs with respect to auditory speech perception, and receptive vocabulary and/or EF? DESIGN: We compared two groups of children with severe HL, profound HL or deafness, with CIs or HAs, matched for gender, test age (range, 8 to 15 years), socioeconomic status, and nonverbal intelligence quotient. Forty-three children had CIs (pure-tone average at 2000 and 4000 Hz >85 dB HL), and 27 children had HAs (mean pure-tone average: 69 dB HL). We measured speech perception at the conversational level (65 dB SPL) and the soft speech perception level (45 dB SPL). We established receptive vocabulary using the Peabody Picture Vocabulary Test-III-NL. We tested EF using the Delis Kaplan Executive Function System battery and the Dutch Rey Auditory Verbal Learning Test. We employed the Mann-Whitney U test to compare data between the CI and HA groups. We used Chi-square goodness of fit tests to contrast the CI and HA group distributions with the norm data of children who are typically developing (TD). We harnessed Kendall's Tau-b to investigate relationships between the study variables. RESULTS: Both groups of children, with CIs and Has, obtained ceiling scores for perception of speech on a conversational level. However, the HA group exhibited significantly lower perception on a soft speech level scores (68 %) than the CI group (87%). No difference was present between the receptive vocabulary distributions of the CI and HA groups. The median receptive vocabulary standard scores for both groups were well within the normal range (CI group: 93; HA group: 96). In addition, we did not find any difference in EF between the CI and HA groups. For planning and verbal memory, the distributions of observed scores for children with CIs were different from the expected distributions of children who are TD. In both groups, a large proportion of children obtained below-average scores for planning (CI: 44%; HA: 33%) and for long-term verbal memory (CI: 44%; HA: 35%). In the HA group, perception at a soft speech level was associated with receptive vocabulary and planning. In the CI group, we did not find any associations. CONCLUSIONS: Both groups of children with severe and profound HL with HAs exhibit less favorable auditory perception on the soft speech level, but not at a conversational level, compared to children who are HH or deaf with CIs. Both groups, children with CIs and HAs, only exhibit more problems in planning and verbal memory than the norm groups of children who are TD. The results indicate that to obtain age-appropriate levels of receptive vocabulary and EF, the perception at the soft speech level is a necessary but not sufficient prerequisite

Mitochondrial function, grip strength, and activity are related to recovery of mobility after a total knee arthroplasty

Low muscle quality and a sedentary lifestyle are indicators for a slow recovery after a total knee arthroplasty (TKA). Mitochondrial function is an important part of muscle quality and a key driver of sarcopenia. However, it is not known whether it relates to recovery. In this pilot study, we monitored activity after TKA using a wrist mounted activity tracker and assessed the relation of mitochondrial function on the rate of recovery after TKA. Additionally, we compared the increase in activity as a way to measure recovery to traditional outcome measures. Patients were studied 2 weeks before TKA and up to 6 months after. Activity was monitored continuously. Baseline mitochondrial function (citrate synthase and complex [CP] 1-5 abundance of the electron transport chain) was determined on muscle tissue taken during TKA. Traditional outcome measures (Knee Injury and Osteoarthritis Outcome Score [KOOS], timed up-and-go [TUG] completion time, grip, and quadriceps strength) were performed 2 weeks before, 6 weeks after, and 6 months after TKA. Using a multivariate regression model with various clinical baseline parameters, the following were significantly related to recovery: CP5 abundance, grip strength, and activity (regression weights 0.13, 0.02, and 2.89, respectively). During recovery, activity correlated to the KOOS-activities of daily living (ADL) score (r = 0.55, p = 0.009) and TUG completion time (r = -0.61, p = 0.001). Mitochondrial function seems to be related to recovery, but so are activity and grip strength, all indicators of sarcopenia. Using activity trackers before and after TKA might give the surgeon valuable information on the expected recovery and the opportunity to intervene if recovery is low