+Gz Exposure and Flight Duty Limitations

BACKGROUND: High +Gz exposure is known to cause spinal problems in fighter pilots, but the amount of tolerable cumulative +Gz exposure or its intensity is not known. The aims of this study were to assess possible breaking points during a flight career and to evaluate possible determinants affecting pilots’ spines. METHODS: Survival analysis was performed on the population who started their jet training in 1995–2015. The endpoint was permanent flight duty restriction due to spinal disorder. Then the quantified Gz exposure and possible confounding factors were compared between those pilots with permanent flying restriction and their matched controls. Cumulative Gz exposure was measured sortie by sortie with fatigue index (FI) recordings. FI is determined by the number of times certain levels of Gz are exceeded during the sorties. RESULTS: T he linear trend of the survival curve indicates an annual 0.86% drop out rate due to spinal problems among the fighter pilot population. A conditional logistic regression did not find any difference in the FI between cases and controls (OR 0.96, 95%CI 0.87–1.06). No statistical difference was found for flight hours, a sum of intensive flying periods, fitness tests, or with nicotine product use. Additionally, a maximum +Gz limitation without airframe restriction was assessed and is presented as a useful tool to manage loading and developed symptoms. DISCUSSION: No particular breaking point during follow-up or individual factor was found for Gz induced spinal disorders. The results of the study outline the multifactorial nature of the problem. Thus, multifactorial countermeasures are also needed to protect pilots’ health.publishedVersionPeer reviewe

Polymetyyliakrylaatin käyttö lonkan tekonivelkirurgiassa.

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Hävittäjälentäjien niska-hartiaseudun kuormittumisanalyysi

Hävittäjälentäjien niska-hartiaseudun kuormittumisanalyysi Hävittäjälentäjän työ asettaa niska-hartiaseudun toimintakyvylle erittäin suuret vaatimukset. Lennon aikana lihaksiston keskimääräinen kuormittumistaso on korkea, jonka lisäksi esiintyy usein kuormittumispiikkejä, jotka voivat olla hyvinkin suuria. Lentäjien niska-hartiaseudun kuormittuminen johtuu päähän kohdistuvista lennon aikaisista kiihtyvyysvoimista, joiden rasitusta lisää lentäjien käyttämä kypärä. Muita tekijöitä, jotka voivat vielä lisätä kuormittumista ovat mm. alhainen ympäristön lämpötila, pään normaalista poikkeavat asennot kiihtyvyysrasituksen aikana sekä kypärän painoa lisäävät varusteet, kuten yönäkökiikarit. Vaikka tutkimusten perusteella tiedetään hävittäjälentäjien niska-hartiaseudun kuormittuneisuuden olevan korkea, ei kuitenkaan ole selvitetty millä ratkaisuilla kuormittumista voitaisiin pienentää. Lentäjien kaularangan kulumamuutokset on määritetty tietyin edellytyksin ammattitaudiksi. Tutkimuksen avulla pyrittiin tarkentamaan hävittäjälentäjien niska-hartiaseutuun kohdistuvaa kuormittumista ja siten arvioimaan tarkemmin kuormittumisen aiheuttamaa terveysriskiä. Toisaalta pyrittiin selvittämään keinoja, joilla niska-hartiaseutuun kohdistuvaa kuormittumista voitaisiin pienentää, ja siten mahdollisesti vähentää tukirankavaivojen esiintyvyyttä. Kaularangan radiologiset muutokset magneettikuvissa 13 vuoden seuranta-aikana eivät olleet merkittäviä lentäjien ja verrokkien välillä. Lentäjillä muutokset painottuivat enempi kaularangan alaosaan kun verrokeilla ne olivat jakautuneet tasaisemmin. Lentäjien niskan jäähtyminen pakkasella ennen lentoa on merkittävää ja aiheuttaa lihaskuormituksen kasvua lennon aikana, kun jäähtyneet lihakset eivät pysty normaaliin voimantuottoon. Lentäjän kypärä aiheuttaa painollaan lisäkuormitusta kaularangan rakenteisiin ja siihen liitettävät lisälaitteet edelleen lisäävät painoa ja muuttavat painopistettä epäanatomiseksi. Kypärän paino on merkittävämpi kuormitusta lisäävä tekijä kuin siihen liitettävien yönäkökiikareiden paino ja niiden massapiste. Yönäkökiikareiden vaikutus kuormitukseen näyttää kuitenkin olevan merkittävää eri tilanteissa eniten kuormittuvissa lihasryhmissä, eli kaulan tai niskan puolen lihaksissa sen mukaan kumpi lihasryhmä kuormittuu eniten. Lannetuella ei saatu tilastollisesti merkitsevää lennonaikaista kuormituksen vähenemistä missään lihasryhmässä, mutta keskimääräinen lihaskuormitus väheni rangan ojentajalihaksissa niin lanne-, rinta- kuin kaularangan tasalla. Harjoitusinterventiossa verrattiin kaularangan lihaksia vahvistavia voimaharjoitteita trampoliiniharjoituksiin. Molemmissa ryhmissä lennon aikainen kuormitus väheni, merkitsevimmin kaulan ja niskan lihaksissa. Harjoitusryhmien välillä ei tuloksissa ollut eroja. Tulosten pohjalta on lähdetty kehittämään lentäjien ohjaamoergonomian koulutusta ja lajinomaisia harjoitusohjelmia, jotta niska-hartiaseudun kuormittumista voitaisiin paremmin hallita. Jatkotutkimusten tarkoituksena on löytää paremmin tukirankavaivoilta suojaavia tekijöitä. Tähän pyritään selvittämällä yksityiskohtaisemmin kumulatiivisen kuormituksen vaikutusta rangan ennenaikaisiin kulumamuutoksiin sekä tarkentamalla ohjaamoergonomian ja kuormitushuippujen välistä yhteyttä.The aim of the studies presented in this dissertation was to study the degenerative changes in the cervical spine due to high Gz exposure; some suggested contributing factors on the neck muscle strain under Gz; and effects of certain countermeasures in reduction of strain under Gz, The subjects were volunteer cadets undergoing training in the Air Force Academy (AFA) of Finland (Studies II, III, and V) and subsequently followedup during their later career (Study I), and AFA instructor pilots (Study IV). Experimental measures included cervical and lumbar magnetic resonance imaging (MRI) (Study I) and electromyography (EMG) for muscular electrical activity (Studies II-V) and the strength of the cervical flexor, extensor and rotator muscles. In addition to strength measurements and test flights, loads on the neck/shoulder muscles were simulated with a cervical loading test (CLT) (Study V). Skin temperatures were measured with a surface thermometer (Study II), and trampoline was used to simulate G-forces (Studies II-III) and as a training device (Study V). A six-week training consisted of strength training and trampoline exercises, for which purposes two training groups were formed. All changes detected in the cervical spine during the follow-up were minor in both groups. Even though there were no significant differences between the groups, but changes in the pilot group seemed to concentrate in the lower cervical spine, i.e., C5-6 and C6-7, while degenerative changes in the control group were scattered more evenly. Both cold exposure and the extra mass of the helmet increased cervical muscle activity (EMG) under Gz. A regression model showed the increase of 2.6 % in muscle strain for every drop of one centigrade in skin temperature over the sternocleidomastoid muscles (SCM) during cold exposure. The results showed that the higher mass of the helmet had a more significant effect on cervical muscle loading than night vision goggles (NVG), which appeared to affect essentially those muscles that are inherently subjected to the highest loadings, i.e., SCM and cervical erector spinae (CES). There were indications of a tendency towards a lower muscle strain when a lumbar support was worn. Muscle activity (EMG) decreased in all measured erector spinae muscles in the cervical, thoracic, and lumbar regions; but these changes were not statistically significant. Training intervention improved the maximal force production in both groups. Training reduced in-flight muscle strain (%MVC) in both groups most significantly in cervical muscles and in the SCM in particular. CLT measurements yielded similar results. The positive effects of training period, i.e. decreased muscular loading, sustained in cervical area in both training groups (STG and TTG). No statistically significant differences between the groups were discovered. In conclusion, high Gz exposures during over 1200 flight hours caused no significant radiological changes n the spinal column. Both cold exposure and the extra mass of helmet system increased cervical muscle activity (EMG) under Gz. It was hypothesised that Gz induced muscle strain could be reduced by improving the sitting posture with a lumbar support and/or by improving muscular capacity and performance through training. These two means seem to reduce muscle strain to some extent

Polymetyyliakrylaatin käyttö lonkan tekonivelkirurgiassa.

Syventävä työ ei kirjastoss

Hävittäjälentäjien niska-hartiaseudun kuormittumisanalyysi

Hävittäjälentäjien niska-hartiaseudun kuormittumisanalyysi Hävittäjälentäjän työ asettaa niska-hartiaseudun toimintakyvylle erittäin suuret vaatimukset. Lennon aikana lihaksiston keskimääräinen kuormittumistaso on korkea, jonka lisäksi esiintyy usein kuormittumispiikkejä, jotka voivat olla hyvinkin suuria. Lentäjien niska-hartiaseudun kuormittuminen johtuu päähän kohdistuvista lennon aikaisista kiihtyvyysvoimista, joiden rasitusta lisää lentäjien käyttämä kypärä. Muita tekijöitä, jotka voivat vielä lisätä kuormittumista ovat mm. alhainen ympäristön lämpötila, pään normaalista poikkeavat asennot kiihtyvyysrasituksen aikana sekä kypärän painoa lisäävät varusteet, kuten yönäkökiikarit. Vaikka tutkimusten perusteella tiedetään hävittäjälentäjien niska-hartiaseudun kuormittuneisuuden olevan korkea, ei kuitenkaan ole selvitetty millä ratkaisuilla kuormittumista voitaisiin pienentää. Lentäjien kaularangan kulumamuutokset on määritetty tietyin edellytyksin ammattitaudiksi. Tutkimuksen avulla pyrittiin tarkentamaan hävittäjälentäjien niska-hartiaseutuun kohdistuvaa kuormittumista ja siten arvioimaan tarkemmin kuormittumisen aiheuttamaa terveysriskiä. Toisaalta pyrittiin selvittämään keinoja, joilla niska-hartiaseutuun kohdistuvaa kuormittumista voitaisiin pienentää, ja siten mahdollisesti vähentää tukirankavaivojen esiintyvyyttä. Kaularangan radiologiset muutokset magneettikuvissa 13 vuoden seuranta-aikana eivät olleet merkittäviä lentäjien ja verrokkien välillä. Lentäjillä muutokset painottuivat enempi kaularangan alaosaan kun verrokeilla ne olivat jakautuneet tasaisemmin. Lentäjien niskan jäähtyminen pakkasella ennen lentoa on merkittävää ja aiheuttaa lihaskuormituksen kasvua lennon aikana, kun jäähtyneet lihakset eivät pysty normaaliin voimantuottoon. Lentäjän kypärä aiheuttaa painollaan lisäkuormitusta kaularangan rakenteisiin ja siihen liitettävät lisälaitteet edelleen lisäävät painoa ja muuttavat painopistettä epäanatomiseksi. Kypärän paino on merkittävämpi kuormitusta lisäävä tekijä kuin siihen liitettävien yönäkökiikareiden paino ja niiden massapiste. Yönäkökiikareiden vaikutus kuormitukseen näyttää kuitenkin olevan merkittävää eri tilanteissa eniten kuormittuvissa lihasryhmissä, eli kaulan tai niskan puolen lihaksissa sen mukaan kumpi lihasryhmä kuormittuu eniten. Lannetuella ei saatu tilastollisesti merkitsevää lennonaikaista kuormituksen vähenemistä missään lihasryhmässä, mutta keskimääräinen lihaskuormitus väheni rangan ojentajalihaksissa niin lanne-, rinta- kuin kaularangan tasalla. Harjoitusinterventiossa verrattiin kaularangan lihaksia vahvistavia voimaharjoitteita trampoliiniharjoituksiin. Molemmissa ryhmissä lennon aikainen kuormitus väheni, merkitsevimmin kaulan ja niskan lihaksissa. Harjoitusryhmien välillä ei tuloksissa ollut eroja. Tulosten pohjalta on lähdetty kehittämään lentäjien ohjaamoergonomian koulutusta ja lajinomaisia harjoitusohjelmia, jotta niska-hartiaseudun kuormittumista voitaisiin paremmin hallita. Jatkotutkimusten tarkoituksena on löytää paremmin tukirankavaivoilta suojaavia tekijöitä. Tähän pyritään selvittämällä yksityiskohtaisemmin kumulatiivisen kuormituksen vaikutusta rangan ennenaikaisiin kulumamuutoksiin sekä tarkentamalla ohjaamoergonomian ja kuormitushuippujen välistä yhteyttä.The aim of the studies presented in this dissertation was to study the degenerative changes in the cervical spine due to high Gz exposure; some suggested contributing factors on the neck muscle strain under Gz; and effects of certain countermeasures in reduction of strain under Gz, The subjects were volunteer cadets undergoing training in the Air Force Academy (AFA) of Finland (Studies II, III, and V) and subsequently followedup during their later career (Study I), and AFA instructor pilots (Study IV). Experimental measures included cervical and lumbar magnetic resonance imaging (MRI) (Study I) and electromyography (EMG) for muscular electrical activity (Studies II-V) and the strength of the cervical flexor, extensor and rotator muscles. In addition to strength measurements and test flights, loads on the neck/shoulder muscles were simulated with a cervical loading test (CLT) (Study V). Skin temperatures were measured with a surface thermometer (Study II), and trampoline was used to simulate G-forces (Studies II-III) and as a training device (Study V). A six-week training consisted of strength training and trampoline exercises, for which purposes two training groups were formed. All changes detected in the cervical spine during the follow-up were minor in both groups. Even though there were no significant differences between the groups, but changes in the pilot group seemed to concentrate in the lower cervical spine, i.e., C5-6 and C6-7, while degenerative changes in the control group were scattered more evenly. Both cold exposure and the extra mass of the helmet increased cervical muscle activity (EMG) under Gz. A regression model showed the increase of 2.6 % in muscle strain for every drop of one centigrade in skin temperature over the sternocleidomastoid muscles (SCM) during cold exposure. The results showed that the higher mass of the helmet had a more significant effect on cervical muscle loading than night vision goggles (NVG), which appeared to affect essentially those muscles that are inherently subjected to the highest loadings, i.e., SCM and cervical erector spinae (CES). There were indications of a tendency towards a lower muscle strain when a lumbar support was worn. Muscle activity (EMG) decreased in all measured erector spinae muscles in the cervical, thoracic, and lumbar regions; but these changes were not statistically significant. Training intervention improved the maximal force production in both groups. Training reduced in-flight muscle strain (%MVC) in both groups most significantly in cervical muscles and in the SCM in particular. CLT measurements yielded similar results. The positive effects of training period, i.e. decreased muscular loading, sustained in cervical area in both training groups (STG and TTG). No statistically significant differences between the groups were discovered. In conclusion, high Gz exposures during over 1200 flight hours caused no significant radiological changes n the spinal column. Both cold exposure and the extra mass of helmet system increased cervical muscle activity (EMG) under Gz. It was hypothesised that Gz induced muscle strain could be reduced by improving the sitting posture with a lumbar support and/or by improving muscular capacity and performance through training. These two means seem to reduce muscle strain to some extent

MRI findings and physical performance as predictors of flight-induced musculoskeletal pain incidence among fighter pilots

Study aim: The aim of this study was to evaluate the possible association of pre-career magnetic resonance imaging (MRI) findings and physical performance level with possible musculoskeletal disorders during jet flight training. Material and methods: The study group consisted of 73 fighter pilots who had undergone pre-career cervical and lumbar spine MRI. Physical performance of a subgroup of the pilots (n = 67) was measured initially at the same time and followed up to the fast jet training phase (ranging from 3.8 to 7.0 years). Musculoskeletal pain history during pilot training was taken from the medical charts. MRI findings and physical performance were associated with perceived clinical complaints during the follow-up. Results: 82% of the cervical and 92% of the lumbar spines showed abnormalities at at least one disk level. MRI did not reveal significant cervical degeneration. Thirteen disk bulges in the lumbar spine were discovered, while 5 pilots had listhesis and/or osteophyte formation on the spine (lumbar vertebra 4/sacroiliac joint level, L4-SI). 41% of the studied pilots suffered spinal symptoms during the follow-up, but only 16% and 17% of the cervical and lumbar MRI findings, respectively, were associated with subsequent symptoms. Endurance and strength levels were not, but lower body motor skills were, strongly (relative risk, RR 0.46) associated with a decreased number of flight-induced medical appointments in the early flight career. Conclusions: Minor MRI findings have no predictable value in the very early flight career. Nevertheless, versatile, skills/ power-oriented exercises before the flight career seem to be occupationally beneficial in reducing musculoskeletal disorders.peerReviewe

Disc herniations in astronauts: What causes them, and what does it tell us about herniation on earth?

PURPOSE: Recent work showed an increased risk of cervical and lumbar intervertebral disc (IVD) herniations in astronauts. The European Space Agency asked the authors to advise on the underlying pathophysiology of this increased risk, to identify predisposing factors and possible interventions and to suggest research priorities. METHODS: The authors performed a narrative literature review of the possible mechanisms, and conducted a survey within the team to prioritize research and prevention approaches. RESULTS AND CONCLUSIONS: Based on literature review the most likely cause for lumbar IVD herniations was concluded to be swelling of the IVD in the unloaded condition during spaceflight. For the cervical IVDs, the knowledge base is too limited to postulate a likely mechanism or recommend approaches for prevention. Basic research on the impact of (un)loading on the cervical IVD and translational research is needed. The highest priority prevention approach for the lumbar spine was post-flight care avoiding activities involving spinal flexion, followed by passive spinal loading in spaceflight and exercises to reduce IVD hyper-hydration post-flight

Cervical spine and muscle adaptation after spaceflight and relationship to herniation risk:protocol from 'Cervical in Space' trial

BACKGROUND: Astronauts have a higher risk of cervical intervertebral disc herniation. Several mechanisms have been attributed as causative factors for this increased risk. However, most of the previous studies have examined potential causal factors for lumbar intervertebral disc herniation only. Hence, we aim to conduct a study to identify the various changes in the cervical spine that lead to an increased risk of cervical disc herniation after spaceflight. METHODS: A cohort study with astronauts will be conducted. The data collection will involve four main components: a) Magnetic resonance imaging (MRI); b) cervical 3D kinematics; c) an Integrated Protocol consisting of maximal and submaximal voluntary contractions of the neck muscles, endurance testing of the neck muscles, neck muscle fatigue testing and questionnaires; and d) dual energy X-ray absorptiometry (DXA) examination. Measurements will be conducted at several time points before and after astronauts visit the International Space Station. The main outcomes of interest are adaptations in the cervical discs, muscles and bones. DISCUSSION: Astronauts are at higher risk of cervical disc herniation, but contributing factors remain unclear. The results of this study will inform future preventive measures for astronauts and will also contribute to the understanding of intervertebral disc herniation risk in the cervical spine for people on Earth. In addition, we anticipate deeper insight into the aetiology of neck pain with this research project. TRIAL REGISTRATION: German Clinical Trials Register, DRKS00026777. Registered on 08 October 2021. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12891-022-05684-0