31 research outputs found
Surgery versus non-operative treatment for ER-stress unstable Weber-B unimalleolar fractures : A study protocol for a prospective randomized non-inferiority (Super-Fin) trial
Publisher Copyright: ©Roughly two-thirds of ankle fractures are unimalleolar injuries, the Weber B-type fibula fracture being by far the most common type. Depending on the trauma and the accompanying soft-tissue injury, these fractures are either stable or unstable. Current clinical practice guidelines recommend surgical treatment for unstable Weber B-type fibula fractures. An ongoing randomized, parallel group, non-inferiority trial comparing surgery and non-operative treatment for unstable Weber B-type ankle fractures with allocation ratio 1:1. The rationale for non-inferiority design is as follows: By being able to prove non-inferiority of non-operative treatment, we would be able to avoid complications related to surgery. However, the primary concern related to non-operative treatment is increased risks of ankle mortise incongruency, leading to secondary surgery, early post-traumatic osteoarthritis and poor function. After providing informed consent, 126 patients aged 16 years or older with an unimalleolar Weber B-type unstable fibula fracture were randomly assigned to surgery (open reduction and internal fixation) or non-operative treatment (6-week cast immobilization). We have completed the patient enrolment and are currently in the final stages of the 2-year follow-up. The primary, non-inferiority outcome is the Olerud-Molander Ankle Score (OMAS) at 2 years (primary time point). The predefined non-inferiority margin is set at 8 OMAS points. Secondary outcomes include the Foot and Ankle Score, a 100 mm Visual Analogue Scale for function and pain, the RAND-36-Item Health Survey for health-related quality-of-life, the range-of-motion of the injured ankle, malunion (ankle joint incongruity) and fracture union. Treatment-related complications and harms; symptomatic non-unions, loss of congruity of the ankle joint, reoperations and wound infections will also be recorded. We hypothesize that non-operative treatment yields non-inferior functional outcome to surgery, the current standard treatment, with no increased risk of harms.Peer reviewe
Preoperative hemoglobin count and prognosis of esophageal cancer, a population-based nationwide study in Finland
Publisher Copyright: © 2021Background: The prognostic value of preoperative hemoglobin in patients undergoing esophagectomy is unknown. The aim of this study was to examine whether preoperative hemoglobin is associated with prognosis in patients undergoing esophagectomy for cancer. Materials and methods: This was a population-based nationwide retrospective cohort study in Finland, using Finnish National Esophago-Gastric Cancer Cohort (FINEGO). Esophagectomy patients with available preoperative hemoglobin measurement were included. Multivariable cox regression provided hazard ratios (HR) with 95% confidence intervals (CI), adjusted for calendar period of surgery, age at surgery, sex, comorbidity (Charlson Comorbidity Index), tumor histology, tumor stage, neoadjuvant therapy, type of surgery (minimally invasive or open) and annual hospital volume. Results: Of the 1313 patients, 932 (71.0%) were men and 799 (60.9%) had esophageal adenocarcinoma. Overall all-cause mortality was significantly higher in the lowest hemoglobin count tertile (HR 1.26 (1.07â1.47)) compared to the highest tertile, but this association was attenuated after adjustment for confounding. No differences were found between the preoperative hemoglobin groups in the adjusted analyses of 90-day all-cause, 5-year all-cause, and 5-year cancer-specific mortality. Conclusion: In this population-based nationwide study, preoperative hemoglobin count had no independent prognostic significance in esophageal cancer.Peer reviewe
Syndesmotic Fixation in Supination-External Rotation Ankle Fractures: A Prospective Randomized Study
Article Ankle fractures are the most common injuries treated operatively by orthopedic surgeons
Forward acceleration of the centre of mass during ski skating calculated from force and motion capture data
LÀmpötilan PID-sÀÀtö reaaliaikajÀrjestelmÀssÀ
Kajaanin ammattikorkeakoululle hankittiin kevÀÀllÀ 2006 uusi mittaustekniikan laitteisto. TÀmÀ laitteisto oli National
Instrumentsin CompactRIO. Lopputyön tarkoituksena oli laitteiston kÀyttöönotto, lÀmpötilanohjaussovelluksen
rakentaminen ja laitteiston testaus Ziegler-Nicholas-menetelmÀn PID-sÀÀdöllÀ.
MittausjÀrjestelmÀ koostui CompactRIO-laitteistosta, jossa oli reaaliaikakontrolleri ja FPGA-piiri sekÀ kaksi I/Omoduulia,
lÀhtöön ja tuloon. Ohjattavana prosessina toimi yksinkertainen lÀmpötilansÀÀtö, joka oli toteutettu
tehovastuksen ja siihen liitetyn Pt100-lÀmpötila-anturin avulla. LisÀksi jÀrjestelmÀssÀ oli kaksi sovitinyksikköÀ,
joilla signaalia vahvistettiin CompactRIO:n tulossa ja lÀhdössÀ.
TyötÀ varten tehtiin kolme ohjelmaa, yksi CompactRIO:n FPGA-piirille, yksi CompactRIO:n reaaliaikakontrollerille
ja yksi isÀntÀtietokoneelle. Ohjelmien teossa kÀytettiin National Instrumentsin LabVIEW-ohjelmistoa.
Tuloksena saatiin toimiva sÀÀtöjÀrjestelmÀ, jossa tieto lÀmpöprosessista kulki anturilta kahden laitteen ja ohjelman
kautta isÀntÀtietokoneen ohjelmalle. Prosessinohjaustieto siirtyi isÀntÀtietokoneelta takaisin lÀmpötilansÀÀtöprosessiin.
Testauksessa tehtiin neljÀ testimittausta, joissa lÀmpötilan asetusarvo nostettiin arvosta 20 °C arvoon 100 °C, ja
seurattiin jÀrjestelmÀn vastetta eri PID-arvoilla. Testimittausten perusteella Ziegler-Nicholas-menetelmÀn PIsÀÀtö
osoittautui selvÀsti parhaaksi sÀÀtömenetelmÀksi tÀssÀ jÀrjestelmÀssÀ.
CompactRIO-laite on erittÀin toimiva tiedonkeruu- ja ohjauslaite. SillÀ voidaan mitata useita erilaisia prosesseja,
koska laitteeseen voidaan kiinnittÀÀ erilaisia I/O-moduuleja, joilla voidaan mitata eri asioita. TÀssÀ sovelluksessa
ei nÀhty CompactRIO:n todellista suorituskykyÀ, koska ohjattava prosessi oli suhteellisen hidas.In the spring 2006 new measurement equipment from National Instruments, called CompactRIO, was acquired
to Kajaani University of Applied Sciences. This CompactRIO equipment is used to control a temperature process.
The measurement system consists of the CompactRIO equipment, two connection units and a resistor which is
heated. The temperature of the resistor was read with the Pt100 temperature sensor. Three control programs
were made for this project, one for the CompactRIOâs FPGA-chip, one for the CompactRIOâs Real-Time Controller
and one for the host computer. National Instrumentâs LabVIEW-software was used to build the control
programs.
Four test measurements were made to test the functionality of the system. In the tests the set point of the
temperature was raised from 20 °C to 100 °C. Different PID-values were used in the different measurements.
After every measurement the response of the system was notice. The results showed that the Ziegler-Nicholas
PI-method was the best controlling method in this study.
The CompactRIO equipment is very useful in various measurement tasks. In this case the speed of the
temperature change was too slow to show the real performance of CompactRIO
Biomechanics in cross-country skiing skating technique and measurement techniques of force production
Requirements of a successful skier have changed during last decades due to e.g.
changes in race forms and developments of equipment. The purpose of this thesis
was to clarify in four Articles (I-IV) what are the requests modern skate skiing
sets for the athletes in a biomechanical point of view. Firstly, it was explained
how skiers control speed from low to maximal speeds (I). Secondly, the
effects of long simulated ski race were determined with traditional force measurement
methods (III) as well as with novel propulsion methods (IV). During
the work process a need for updated multi-dimensional leg force sensor appeared
and it was materialized (II). During the thesis 16 national level athletes
participated in the different experiments of the study. Measurements for controlling
speed were carried out with 3D force sensor for legs and pole force sensor
for arms. Conventional cycle, force and joint kinematic parameters were
analysed (I). After, a need for reliable force sensor appeared especially for anterior-
posterior forces. Two 2D force binding sensors (Skate binding: vertical and
medio-lateral directions and Classic binding: vertical and anterior-posterior directions)
were designed and built. Validation was done in different temperatures
and mechanical stress situations as well as in diverse normal and sport
specific jumping situations and skiing with both techniques (II). Effects of simulated
ski skating race (20 km) on athletesâ performance were analysed by direct
force measurements from legs with updated force binding and from arms with
pole force sensors. In addition, EMG and cycle definitions were conducted (III).
Novel analysing method for propulsion was tested on the same data using additional
3D movement analysis (IV). Skiers control their speed during V2-
skating with cycle length and cycle rate while length is dominant with lower
speeds and rate governs with higher speeds. Force production of the arms and
legs with increasing speeds is aided by vertical oscillation of COM (I). New
force binding system was verified to be valid for skate skiing while some improvements
were needed for classic binding (II). Effects of long simulated race
were detected with slower skiing speed at the end of race caused by lower EMG
activity and force production as indications of fatigue (III). Propulsion analyses
gave new insights on athlete diagnostics by revealing the decrement of force
production especially with legs which was overlooked with traditional analysing
methods (IV).
Keywords: cross-country skiing, speed adaptation, force measurement, fatigue,
propulsionMenestyksekkÀÀn hiihtÀjÀn vaatimukset ovat muuttuneet viime aikoina merkittÀvÀsti
esimerkiksi uusien kilpailumuotojen ja vÀlinekehityksen myötÀ. TÀmÀn
tutkimuksen tarkoituksena oli selvittÀÀ neljÀssÀ artikkelissa (I-IV), mitÀ vaatimuksia
nykyaikainen luisteluhiihto asettaa hiihtÀjÀlle biomekaanisesta nÀkökulmasta.
Ensiksi selvitettiin kuinka hiihtÀjÀt kontrolloivat nopeutta hitaasta
maksimaaliseen vauhtiin (I). Toiseksi tutkittiin pitkÀn simuloidun luisteluhiihtokilpailun
vaikutuksia hiihtÀjÀÀn perinteisillÀ voiman analysointimenetelmillÀ
(III), sekÀ uudella propulsiovoimamenetelmÀllÀ (IV). Työprosessin aikana todettiin
tarve uudelle voimanmittausmenetelmÀlle ja se toteutettiin (II). TÀmÀn
tutkielman aikana 16 kansallisen tason hiihtÀjÀÀ osallistui tutkimuksen eri osiin.
Nopeuskontrollitutkimuksessa kÀytettiin 3D voima-anturia jaloille ja sauvavoima-
anturia kÀsille. LisÀksi mitattiin sykli- ja nivelkulmamuuttujia. TÀmÀn
työ-osion aikana todettiin tarve tarkemmalle jalkojen voimanmittausmenetelmÀlle,
erityisesti pitkittÀiseen suuntaan (I). Kaksi 2D voima-anturia (pysty- ja
poikittaisvoima luisteluun sekÀ pysty- ja pitkittÀisvoima perinteiseen) suunniteltiin,
rakennettiin ja validoitiin. Validointi toteutettiin eri lÀmpötiloissa ja mekaanisissa
kuormituksissa, sekÀ erilaisissa lajinomaisissa hypyissÀ. LisÀksi anturit
testattiin referenssimenetelmiÀ vastaan lumella hiihdettÀessÀ molemmilla
tekniikoilla (II). Simuloidun luisteluhiihtokilpailun (20 km) vaikutuksia urheilijoiden
voimantuottoihin tutkittiin uudella 2D voimanmittauslaitteistolla jaloista
ja sauvavoima-anturilla kÀsistÀ. LisÀksi tutkittiin lihasaktiivisuutta ja syklimuuttujia
(III). Uutta propulsiovoimamenetelmÀÀ testattiin samalla datalla 3D
liikeanalyysin kanssa (IV). HiihtĂ€jĂ€t kontrolloivat nopeutta hiihtosyklillĂ€ ja â
frekvenssillÀ, joista syklin mitan kasvattaminen on hallitsevampi matalammilla
nopeuksilla, ja frekvenssin nostaminen kovilla nopeuksilla. Massakeskipisteen
lisÀÀntynyt pystysuuntainen liike edesauttaa voimantuottojen kasvua hiihtonopeuden
kasvaessa (I). Uusi voimanmittausmenetelmÀ osoitettiin luotettavaksi
luisteluhiihtoon, mutta perinteisen hiihdon anturiin tarvitaan parannuksia (II).
PitkÀ luisteluhiihtokilpailu aiheutti vÀsymystÀ, mikÀ nÀhtiin hidastuneena loppukirivauhtina.
TÀmÀ johtui heikentyneestÀ lihasaktiivisuudesta ja sitÀ kautta
madaltuneista voimantuotoista (III). Propulsiovoima-analyysi paljasti suuremman
voimien laskun jaloissa, mitÀ ei pystytty todentamaan perinteisillÀ voiman
analysointimenetelmillÀ (IV).
Avainsanat: maastohiihto, nopeusmuutokset, voimanmittaukset, vÀsymys,
propulsi
Suksen luisto-ominaisuuksien vaikutukset V2-tekniikan voimantuottoon
Ohtonen, Olli 2010. Suksen luisto-ominaisuuksien vaikutukset V2-tekniikan voiman-tuottoon. Biomekaniikan pro gradu -työ, syksy 2010. Liikuntabiologian laitos, JyvÀsky-lÀn yliopisto, 64 s.
Perinteisen hiihdon voimantuottoa on tutkittu paljon (esim. Komi 1985/1987, VÀ-hÀsöyrinki 2008, Lindinger 2009), mutta 3D-voimamittauksia luisteluhiihdosta ei ole juurikaan tehty. Suksen luisto-ominaisuuksien vaikutuksista suorituskykyyn ja biome-kaanisiin ominaisuuksiin puhutaan paljon mutta, niitÀ ei ole vielÀ tutkittu. TÀmÀn tutki-muksen tavoitteena oli suunnitella ja rakentaa toimiva 3D-voimanmittauslaitteisto ja tutkia kuinka erilailla voidellut sukset vaikuttavat luisteluhiihdon sykliin sekÀ kÀsien ja jalkojen voimantuottoon.
Kehitetty siteeseen kiinnitettÀvÀ voimanmittauslaitteisto rakennettiin (JyvÀskylÀn yli-opisto). Laite kalibroitiin ja sen toimintaa vertailtiin jo olemassa olevia voimanmittaus-laitteita, suksenliikutuslaite (Kolehmainen 2006) ja pitkÀt voimalevyt (VÀhÀsöyrinki 2008), vastaan. LisÀksi testiin luisteluhiihtomittaukset, joissa 10 laadukasta kansallisen tason hiihtÀjÀÀ suoritti neljÀllÀ eri nopeudella hiihtosuorituksia 100 metriÀ pitkÀÀn tasai-sen kulman (4°) omaavaan hiihtonousuun V2-tekniikalla kahdella eri lailla valmistellulla suksella (hidas suksi ja nopea suksi).
Hitaan suksen kitka oli 79 % suurempi kuin nopean suksen. TÀmÀ johti 6,4 % hitaam-paan maksiminopeuteen hitaalla suksella. Syklin kesto lyheni ja frekvenssi kasvoi hitaalla suksella. TÀmÀ johtui pÀÀasiassa palautumisajan lyhenemisestÀ syklin sisÀllÀ. Toinen merkittÀvÀ tekijÀ suuremman kitkan kompensoimisessa hitaalla suksella on ylÀvartalon voimantuoton kasvu (sauvan huippuvoima ja keskimÀÀrÀinen työntövoima syklin aikana) hitaalla suksella. Pystysuorissa jalkavoimissa ei havaittu muutoksia, mutta poikittaissuuntaiset jalkavoimat (jalan huippuvoima poikittaiseen suuntaan) olivat suu-rempia ja hitaalla suksella.
Voimanmittauslaitteisto osoittautui toimivaksi, mutta suksen suuntaisten voimien mit-taamista tulee vielÀ kehittÀÀ. Hitaan suksen aiheuttama suurempi kitka vakionopeuksilla kompensoidaan lyhentÀmÀllÀ syklin kestoa (ja nostamalla frekvenssiÀ), mikÀ tapahtuu pÀÀasiassa palautumisaikaa lyhentÀmÀllÀ. YlÀvartalon voimantuoton kasvu on myös merkittÀvÀ tekijÀ suuremman kitkan kompensoimisessa, mikÀ on linjassa aikaisempien tutkimusten kanssa (Millet ym. 1998). Jalkojen voimantuotossa poikittaisvoimien kasvu, mikÀ voi johtua suksen voimakkaammasta kÀÀntÀmisestÀ kantille, on havaittavissa hitaalla suksella. Pystysuuntaisissa jalkavoimissa muutoksia ei ole havaittavissa
Contribution and effectiveness of ski and pole forces in selected roller skiing techniques on treadmill at moderate inclines
Background: Most of the studies about the effects of incline on cross-country skiing are related to the metabolic efficiency. The effective skiing biomechanics has also been indicated to be among the key factors that may promote good performance. The aims of this study were to provide biomechanical characteristics and investigate the relative contribution and effectiveness of ski and pole forces in overcoming the total external resistance with double poling (DP) and Gear 3 (G3) techniques at varying moderate uphill inclines.
Methods: 10 male cross-country skiers participated in this study. Custom-made force measurement bindings, pole force sensors, and an 8-camera Vicon system were used to collect force data and ski and pole kinematics at 3°, 4° and 5° with 10 km/h skiing speed.
Results: The cycle length (CL) decreased by 10% and 7% with DP and G3 technique from 3° to 5° (pâ<â0.001, pâ<â0.001). The cycle rate (CR) increased by 13% and 9% from 3° to 5° with DP and G3 technique respectively. From 3° to 5°, the peak pole force increased by 25% (pâ<â0.001) and 32% (pâ<â0.001) with DP and G3 technique. With DP technique, the average cycle propulsive force (ACPF) increased by 46% (pâ<â0.001) from 3° to 5°and with G3 technique, the enhancement for ACPF was 50% (pâ<â0.001). In G3 technique, around 85% was contributed by poles in each incline.
Conclusion: The higher power output in overcoming the total resistance was required to ski at a greater incline. With DP technique, the upper body demands, and technical effectiveness were increasing with incline. With G3 technique, the role of external pole work for propulsion is crucial over different terrains while role of legs may stay more in supporting the body against gravity and repositioning body segments.peerReviewe
The Development and Precision of a Custom-Made Skitester
In the sport of cross-country skiing, equipment has a direct influence on results. Ski teams do extensive testing of different ski base grinds and products on a yearly basis. To achieve reliable results, the quality of methods used for testing skis needs to be taken in to account in addition to factors including the physical characteristics of testing personnel and changes in weather conditions. The aim of this study was to introduce a custom-made skitester, that was developed for testing skis on real snow, in laboratory conditions, and to evaluate its precision. The current skitester is capable of glide testing both classic and skate skis as well as kick simulation for the testing of grip waxes. In the present study, glide testing precision was completed in three different conditions. Velocity and pressure of skis were evaluated in three different temperature conditions. During kick simulation, precision was determined in one temperature condition. For glide testing, the precision of the measurement unit was able to distinguish the differences between skis with a relative variation of 0.6â1.1%. However, the track preparation process caused variation. For kick simulation, precision of the measurement unit was slightly higher (2.5%), and track preparation caused less variation. The skitester is capable of distinguishing the differences between both skate and classic cross-country skis with certain limitations.peerReviewe
Validation of portable 2D force binding systems for cross-country skiing
The aim of the present study was to design, construct and scientifically validate a two-dimensional force measurement binding system for cross-country skiing. The system consists of two force measurement bindings. One binding was designed for analysing classic skiing (vertical and anteriorâposterior [along the ski] force components) and the other one for skate (freestyle) skiing (vertical and medio-lateral [transverse to the ski] force components). Validation was accomplished using a three-step process: (1) accuracy tests for the sensors in two temperatures, (2) sport-specific imitation jump test on standard force plates in a laboratory and (3) comparing the system against force measurement reference systems that are currently used when skiing on snow. During sport-specific imitation jumps, differences in peak forces and impulses between the classic binding and the reference systems ranged from 8.0 to 19.9 % and were two to three times greater compared to differences between the skate binding and the reference systems (range â5.9 to 5.5 %). However, high similarity coefficients were observed with both bindings (classic binding 0.990â0.996, skate binding 0.996â0.999) compared to the reference systems. Based on these results, the skate binding was shown to be fully valid for use in field measurements of skate skiing, whereas some improvements have to be performed in the construction and sensor placements for the classic binding (vertical as well as anteriorâposterior force component).peerReviewe