Cluster analysis successfully identifies clinically meaningful knee valgus moment patterns: frequency of early peaks reflects sex-specific ACL injury incidence

Publisher's version (útgefin grein).Background: Biomechanical studies of ACL injury risk factors frequently analyze only a fraction of the relevant data, and typically not in accordance with the injury mechanism. Extracting a peak value within a time series of relevance to ACL injuries is challenging due to differences in the relative timing and size of the peak value of interest. Aims/hypotheses: The aim was to cluster analyze the knee valgus moment time series curve shape in the early stance phase. We hypothesized that 1a) There would be few discrete curve shapes, 1b) there would be a shape reflecting an early peak of the knee valgus moment, 2a) youth athletes of both sexes would show similar frequencies of early peaks, 2b) adolescent girls would have greater early peak frequencies. Methods: N = 213 (39% boys) youth soccer and team handball athletes (phase 1) and N = 35 (45% boys) with 5 year follow-up data (phase 2) were recorded performing a change of direction task with 3D motion analysis and a force plate. The time series of the first 30% of stance phase were cluster analyzed based on Euclidean distances in two steps; shape-based main clusters with a transformed time series, and magnitude based sub-clusters with body weight normalized time series. Group differences (sex, phase) in curve shape frequencies, and shape-magnitude frequencies were tested with chi-squared tests. Results: Six discrete shape-clusters and 14 magnitude based sub-clusters were formed. Phase 1 boys had greater frequency of early peaks than phase 1 girls (38% vs 25% respectively, P < 0.001 for full test). Phase 2 girls had greater frequency of early peaks than phase 2 boys (42% vs 21% respectively, P < 0.001 for full test). Conclusions: Cluster analysis can reveal different patterns of curve shapes in biomechanical data, which likely reflect different movement strategies. The early peak shape is relatable to the ACL injury mechanism as the timing of its peak moment is consistent with the timing of injury. Greater frequency of early peaks demonstrated by Phase 2 girls is consistent with their higher risk of ACL injury in sports.Funding for the study was provided by The Icelandic Centre for Research (Rannís – Rannis.is), funding codes 120410021, 903271305, 1203250031, and 185359051. The Football Association of Iceland has provided travel funds to the lead author to present findings at a conference. No funding source was involved in the study design, the execution of the study, the data analysis, writing the report, the decision to publish the results, or writing the article.Peer Reviewe

Effects of Sex and Fatigue on Biomechanical Measures During the Drop-Jump Task in Children

Background: Female athletes have a higher rate of anterior cruciate ligament (ACL) injury than males from adolescence and into maturity, which is suggested to result from sex-specific changes in dynamic movement patterns with maturation. Few studies have studied movement strategies and response to fatigue in children. Purpose: To evaluate the effect of fatigue on biomechanical variables associated with increased risk for ACL injury during a drop-jump (DJ) performance in children. Study Design: Controlled laboratory study. Methods: A total of 116 children (mean age, 10.4 years) were recruited from local sports clubs and performed 5 repetitions of a DJ task before and after a fatigue protocol. Kinematic and kinetic data from initial contact (IC) to the first peak vertical ground reaction force (vGRF) were analyzed for both limbs, including limb and fatigue as within-subject factors for analyses between boys and girls. Pearson correlation coefficients were calculated to identify associations between variables of interest. Results: Girls demonstrated greater peak vGRF values than boys (by 8.1%; P < .05), there were greater peak vGRF values for the right limb than the left (by 6.2%; P < .001), and fatigue led to slightly greater values (P < .05). Although weak, the correlation between peak vGRF values and knee flexion excursion was stronger for girls (r = –0.20) than boys (r = –0.08) (P < .006). Fatigue resulted in greater knee flexion angles at IC and less excursion during landing, more so for girls (by 6.1° vs 1.4°; interaction, P < .001), although the knee flexion moment was generally lowered by fatigue (P < .001). Limb asymmetry in knee flexion moments was more pronounced for boys than for girls (interaction, P < .05), contrary to that seen in frontal plane knee moments, where asymmetry was much greater in girls than boys (interaction, P < .001). Conclusion: Even as young athletes, girls and boys seem to adopt dissimilar movement strategies and are differently affected by fatigue.This study was supported by grants from The Icelandic Research Fund (120410023) and the University of Iceland Research FundPeer Reviewe

Timing of Frontal Plane Trunk Lean, Not Magnitude, Mediates Frontal Plane Knee Joint Loading in Patients with Moderate Medial Knee Osteoarthritis

The purpose of this study was to examine the infuence of trunk lean and contralateral hip abductor strength on the peak knee adduction moment (KAM) and rate of loading in persons with moderate medial knee osteoarthritis. Tirty-one males (17 with osteoarthritis, 14 controls) underwent 3-dimensional motion analysis, strength testing of hip abductors, and knee range of motion (ROM) measures, as well as completing the knee osteoarthritis outcome score (KOOS). No diferences were found between groups or limbs for gait cycle duration, but the osteoarthritis group had longer double-limb support during weight acceptance (p < 0.001) and delayed frontal plane trunk motion towards the stance limb (p < 0.01). Tis was refected by a lower rate of loading for the osteoarthritis group compared to controls (p < 0.001), whereas no diferences were found for peak KAM. Trunk angle, contralateral hip abductor strength, and BMI explained the rate of loading at the involved knee (p < 0.001), an association not found for the contralateral knee or control knees. Prolonged trunk lean over the stance limb may help lower peak KAM values. Rate of frontal plane knee joint loading may partly be mediated by the contralateral limb’s abductor strength, accentuating the importance of bilateral lower limb strength for persons with knee osteoarthritis.Financial support was received from the Icelandic Physiotherapy Association.Peer Reviewe

Timing, not magnitude, of force may explain sex-dependent risk of ACL injury

Purpose The anterior cruciate ligament is loaded through valgus moment, vertical ground reaction force, and internal rotation moment. The aim of this study was to compare the timing of force peaks during early stance between youth girls and boys. Methods One-hundred and twenty-nine team sport athletes aged 9–12 completed a total of 2540 cutting maneuvers captured with an 8-camera motion capture system. Timing of early force peaks was analyzed within 100 ms after ground contact. Results Genders showed different mean (95% CI) time to peak valgus—(32 ms (30–33 ms) vs 37 ms (36–38 ms), P < 0.001) and time to peak internal rotation moments (36 ms (35–37 ms) vs 38 ms (37–39 ms), P = 0.029) but not time to peak vertical ground reaction force [38 ms (37–40 ms) vs 37 ms (36–38 ms, n.s.)]. Girls showed a smaller time between vertical ground reaction force and valgus moment peaks (mean (95% CI) of 1 ms (1–2 ms) vs 7 ms (5–9 ms), P < 0.001), and valgus- and internal rotation moment peaks (0 ms (− 2 to 1.0 ms) vs − 5 ms (− 6 to − 3 ms), P = 0.0003) but not between internal rotation moment and vertical ground reaction force. Conclusions Concurrent force peaks are more common for girls compared with boys, leading to more frequent multi-planar loading of the knee. Timing may explain sex-dependent risk of ACL injuries. Exposure to repeated cutting movements may result in greater ACL injury risk due to timing of knee forces as well as magnitude. Such exposure should be minimized for at-risk athletes. Level of evidence III.Funding for salaries (funding code 120410021) and equipment to conduct measurements [Qualisys motion capture cameras and software (funding code 903271305), and AMTI force plates (funding code 1203250031)] was provided by The Icelandic Centre for Research (Rannís—Rannis.is). The Football Association of Iceland has provided travel funds to the lead author to present findings at a conference. No funding source was involved in the study design, the execution of the study, the data analysis, writing the report, the decision to publish the results, or writing the article.Peer Reviewe

Determinants of physical function in community dwelling old people

Funding Information: The trial is registered at the US National Library of Medicine (No. NCT01074879). Funding Information: This study was part of the IceProQualita project, which was funded by the Icelandic Technology Development Fund (No 071323008), Research Fund of the University of Iceland, a grant from Landspitali University Hospital Research Fund and the Helga Jonsdottir and Sigurlidi Kristjansson Geriatric Research Fund. Publisher Copyright: © 2022, Pacini Editore S.p.A./AU-CNS. All rights reserved.Background. Poor physical function is associated with disability and mortality in old people. Objectives. The aim was to find determinants of physical function in old people. Design. Secondary, cross-sectional analysis. Setting. Community in the Reykjavik, Iceland. Participants. 236 old people (73.7 ± 5.7 years, 58.2% female). Measurements. Timed-up-and-go (TUG), six-minute-walk-for-distance (6MWD), anthropometrics, quadriceps strength, dietary intake, mini-mental-state-examination (MMSE), leisure-time physical activity (LTPA) and blood variables were assessed. Descriptive, bivariate and multivariate statistical analyses were used. Results. There were differences between men and women in energy intake, body composition and muscular strength, but physical function did not differ between men and women. In bivariate analysis, most of the assessed variables correlated with 6MWD and TUG. Stepwise lin-ear models showed that age, body composition, strength, medication, LTPA and MMSE were predictors of physical function but not hematological variables. The association between MMSE and function disappeared when corrected for strength/body weight. Results were similar for both 6MWD and TUG and the strongest predictors in the final models were age and quadriceps strength/body weight. Conclusions. In community dwelling old people, physical function decreases with age. However, it is of clinical relevance that there are modifiable determinants of physical function, in particular strength for a given body weight, LTPA and number of medications, which represent potential targets to maintain physical function in this age group. Our results also indicate that neither cognitive function, nor dietary intake nor blood chemical variables were independently associated with physical function.Peer reviewe

Hemoglobin Concentrations Predict Physical Function After A 12-Week Resistance Exercise Training and Subsequent Changes After 11 Months of Follow-Up Among Community Dwelling Older Adults

Background: Hemoglobin transports oxygen in blood yet its concentrations generally decrease with age. The aim of the study was to examine whether hemoglobin is connected with physical function in older age people. Design: Intervention study. Setting: Community. Participants: Older adults (N=236, 73.7±5.7 years, 58.2% female). Intervention: A 12-week resistance exercise program (3 times/week; 3 sets, 6-8 repetitions at 75-80% of the 1-repetition maximum) was conducted to increase strength and muscle mass of major muscle groups. Measurements: Anthropometrics, muscle strength, timed up and go (TUG in sec), six-minute walking distance (6MWD in m) and blood chemical variables were measured at baseline, endpoint and after 10.7 months followup. The linear regression model was used to examine the association between baseline hemoglobin and physical function outcome. Results: Only about 4% of the participants were anemic. According to calculations baseline hemoglobin was associated with TUG (0.14 to 0.36 sec improvement by 10 g/L increase of hemoglobin) at all-time points, even though this was of borderline significance for baseline (p=0.57) and endpoint (p=0.062). Hemoglobin also predicted endpoint 6 MWD (4.88m), but not at baseline (follow up 6 MWD was not available). Statistical correction for compliance did not influences results. Conclusion: Hemoglobin is positively associated to physical function in community dwelling old aged people. Additionally, we found that baseline hemoglobin is associated to adaptions to 12-week resistance exercise training and changes in physical function during the follow-up.Rannís (No 071323008), Rannsóknarsjóður Háskóla Íslands, Styrkur frá Landspítala Hákólasjúkrahúsi Helga Jonsdottir and Sigurlidi Kristjansson Geriatric Research Fund.Peer Reviewe

Acute epiglottitis as the initial presentation of pediatric Systemic Lupus Erythematosus

We report a case of a 5-year old girl, who initially presented with acute epiglottitis, sepsis and multi-organ failure. She was subsequently diagnosed as having Systemic Lupus Erythematosus. To the best of our knowledge, this article describes the first case of Haemophilus influenzae type f epiglottitis as the initial presentation of SLE in childhood

Ultrasonographic Identification of Muscle Atrophy in Hamstring Muscles after Anterior Cruciate Ligament Repair among Soccer Players: A Case-control Study

Objectives To measure the CSA of the HST musculature measured with ultrasonography in soccer players undergoing ACLR and compare limb differences with healthy controls. Methods A case-control study was performed with patients after anterior cruciate ligament repair (ACLR) and healthy controls in which cross-sectional areas (CSA) obtained using a model TE7 ultrasound machine (MINDRAY ®, USA) in B mode (4.2 to 13 MHz) with a multifrequency linear array transducer (L12-4S). Three CSA images were taken of the semitendinosus muscle (ST) and the long head of the biceps femoris (BFlh), at a distance of 30% and 70% of the ischial tuberosity insertion. Mean differences between groups were analyzed using SPSS v.20 (IBM®, USA), and statistical analyses were performed using non-parametric techniques to determine differences between groups (Student's t-test) and Cohen's correlation coefficient to quantify effect size. Results 14 ACLR operated 17 ± 5.4 months ago and 12 healthy controls (W = 6; M = 20M; 24.5 ± 3.92 years; BMI = 25.1 ± 2.32 kg/m2) were recruited. There were differences between groups in CSA-ST70 (Post-ACLR = 1.43 ± 1.029 cm2 vs Control 2.65 ± 0.664 cm2, T Student = -3.68, 95% CI [-Inf, -0.648], P &lt; 0. 001, ES = -1.418), but not in CSA-ST30 (Post-ACLR = 8.42 ± 1.596 cm2 vs Control 9.16 ± 0.945 cm2, T Student = -1.535; 95% CI [-Inf, -0.0793], P = 0. 068, ES = -0.5607), CSA-BFlh30 (Post-ACLR = 8.79 ± 1.47 cm2 vs Control 8.87 ± 2.312 cm2, T Student = -0.123; 95% CI [-Inf, 1.1049], P = 0.452, ES = -0. 049) or CSA-BFlh70 (Post-ACLR = 6.91 ± 1.011 cm2 vs Control 7.01 ± 1.453 cm2, T Student = -0.214; 95% CI [-Inf, 0.6795], P = 0.416, ES = -0.0783). Conclusion Ultrasound measurement of the CSA can be an image marker to identify muscle weakness or atrophy that predicts functional loss early