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Study Design. Retrospective additional analysis of a prospective follow-up study. Objectives. We aimed to find out whether poor postoperative sagittal alignment increases revisions for adjacent segment disease (ASD) after lumbar spine fusion (LSF) performed for degenerative lumbar spine disease. Summary of Background Data. Revisions for ASD accumulate over time after LSF for degenerative lumbar spine disease. The etiology of ASD is considered multifactorial. Yet, the role of postoperative sagittal balance in this process remains controversial. Materials and Methods. A total of 215 consecutive patients who had undergone an elective LSF surgery for spinal stenosis with (80%) or without (20%) spondylolisthesis were analyzed. Spinal reoperations were collected from the hospital records. Preoperative and postoperative sagittal alignment were evaluated from standing radiographs. The risk of revisions for ASD was evaluated by Cox proportional hazards regression models. Results. We did not find the poor postoperative balance [pelvic incidence-lumbar lordosis (LL) >9°] to significantly increase the risk of revisions for ASD: crude hazard ratio (HR)=1.5 [95% confidence interval (CI): 0.8-2.7], adjusted (by age, sex, pelvic incidence, fusion length, and the level of the caudal end of fusion): HR=1.7 (95% CI: 0.9-3.3). We found higher LL outside the fusion segment (LL-segmental lordosis) to decrease the risk of revisions for ASD: HR=0.9 (95% CI: 0.9-1.0). Conclusion. Poor sagittal balance has only a limited role as a risk factor for the revisions for ASD among patients with degenerative spinal disease. However, the risk for ASD might be the greatest among patients with reduced spinal mobility. publishedVersion

In population-oriented ergonomics product design and musculoskeletal kinetics analysis, digital spine models of different shape, pose and material property are in great demand. The purpose of this study was to construct a parameterized finite element spine model with adjustable spine shape and material property. We used statistical shape model approach to learn inter-subject shape variations from 65 CT images of training subjects. Second order polynomial regression was used to model the age-dependent changes in vertebral material property derived from spatially aligned CT images. Finally, a parametric spine generator was developed to create finite element instances of different shapes and material properties. For quantitative analysis, the generalization ability to emulate spine shapes of different people was evaluated by fitting into 17 test CT images. The median fitting accuracy was 0.8 for Dice coefficient and 0.43 mm for average surface distance. The age-dependent bone density regression curve was also proved to well agree with large population statistics data. Finite element simulation was performed to compare how shape parameters influenced the biomechanics distribution of spine. The proposed parametric finite element whole spine model will assist the design process of new devices and biomechanical simulation towards a wide range of population. peerReviewed

Purpose: The effectiveness of a 12-month home-exercise program on trunk muscle strength after lumbar spine fusion surgery was evaluated. Materials and methods: Three months postoperatively, 98 patients were randomized either to the exercise group (EG), with a progressive 12-month home-based exercise program, or to usual care group (UCG), with one guidance session for light home-exercises. Maximal trunk muscle strength was measured by a strain-gauge dynamometer and trunk extensor endurance was measured by Biering-Sørensen’s test at baseline and after the intervention. Results: The mean change in extension strength during the intervention was 75 N in EG and 58 N in UCG. Flexion strength improved 50 N in UCG and 45 N in EG. Trunk extension/flexion strength ratio changed from 0.90 to 1.02 in EG and from 0.98 to 1.00 in UCG. In EG, Biering-Sørensen’s test improved by 17 s, and in UCG, it improved by 24 s. No statistically significant between-group differences were found in any variables. Median exercise frequency in EG decreased from 2.5×/week during the first two intervention months to 1.7×/week during the last two intervention months. Conclusions: Twelve-month progressive exercise program was equally effective as usual care in improving trunk muscle strength. Home exercise adherence decreased, which may have influenced the strength changes.Implications for rehabilitation The 12-month home-based exercise program was equally as effective as usual care after lumbar spine fusion (LSF) in improving trunk muscle strength, however, the back-specific exercises led to better trunk muscle strength balance in exercise group only. The adherence to the home based exercise program is a challenge; therefore, different techniques could be implemented to provide purposeful support for each individual in their long-term exercising. It is important to recognize those who need more individualized rehabilitation in recovery of the spine function, while others may manage with subtle intervention after LSF.

Objectives: To evaluate the association of thoracic spine (TS) posture and mobility with TS pain. Methods: Participants with TS pain reported maximum, average, and night pain in TS area, and pain summary score was calculated. Upright and sitting TS postures were evaluated by inspection. TS posture and mobility (flexion and extension) were recorded using an inclinometer and a tape measure, respectively. Correlations between posture and mobility assessments were calculated using Spearman rank correlation, the association of TS posture and mobility with TS pain by logistic regression analysis. Results: The participants’ (n = 73, 52 females, age range 22–56) TS pain duration was 12 weeks on average. The correlations for measurements of TS posture and flexion mobility were higher than correlations of other TS measurements being between 0.53 and 0.82. Decreased extension mobility of the upper (from 1st to 6th TS segments; Th1–Th6) TS was associated with higher worst pain (OR 1.04, 95% CI 1.00–1.07) and whole TS with pain sum score (OR 1.05, 95% CI 1.01– 1.08). Less kyphotic whole TS was associated with lower pain sum score (OR 0.96, 95% CI 0.92– 1.00). Greater flexion mobility of upper and lower (Th6–Th12) TS were associated with lower pain sum score (OR 0.96, 95% CI 0.91–1.00, and OR 0.96, 95% CI 0.91–1.00, respectively). Conclusions: Reduced thoracic extension mobility was associated with higher pain scores and the greater flexion mobility with lower pain scores. Future research is warranted to evaluate if treatments geared toward TS extension mobility improvements would result in lower TS pain. peerReviewed

When using ionizing radiation, justification must always be considered due to the possibility of radiation-promoted carcinogenesis. The radiation-induced lifetime risk of cancer mortality is higher in young age. A radiological examination is justified when the benefit to the patient is greater than the expected harm. Although the risk to an individual is small, the concern is attributed to the rapid increase in collective radiation doses, especially related to increased use of CT. Radiographies are still the most frequent examinations using ionizing radiation. The radiation dose of lumbar spine radiography is among the highest, and the radiation is delivered to radiation-sensitive organs. Imaging referral guidelines have been developed to support referrers in selecting and justifying radiological procedures. The purpose of this study was to follow up the effects of active guideline implementation, including education, on the volume and appropriateness of CTs and lumbar spine radiographs on young people in Oulu University Hospital and of spine radiographs in adults in primary care. Furthermore, the aim was to evaluate whether inappropriate lumbar spine radiographs in Oulu University Hospital had relevant findings. A statistically significant reduction in the number of CTs in young people was seen in lumbar spine (-80%), cervical spine (-48%) and head (-21%). The number of all spine radiographs decreased significantly; that of lumbar spine radiographs in university hospital by 37% and spine radiographs in primary care by 51%. The justification of performed examinations improved or remained unchanged in all categories. A significant change was seen in overall appropriateness of CTs, from 71% to 87%. The appropriateness of lumbar spine examinations in Oulu University Hospital and of lumbar spine radiographs in primary care improved significantly. However, the level of appropriateness of different spine radiographs in primary care remained low even after the interventions. The proportion of notable findings in lumbar spine was significantly higher in radiographs that were in accordance with the guidelines than in radiographs that were not. In conclusion, guideline implementation and education can significantly decrease the number of radiological examinations and result in more appropriate examinations. However, persistent follow-up and education seem to be necessary. Tiivistelmä Ionisoivasta säteilystä aiheutuvien haittavaikutusten, erityisesti syöpäriskin, vuoksi ionisoivalle säteilylle altistavilla kuvantamistutkimuksilla tulee olla oikeutus. Säteilystä aiheutuvan elinikäisen syöpäkuoleman riski on suurempi nuorilla. Tutkimus on oikeutettu, kun siitä potilaalle odotettavissa oleva hyöty on suurempi kuin säteilyaltistukseen liittyvä haitta. Vaikka yksilön riski on pieni, väestön nopeasti lisääntyvä kollektiivinen säteilyannos aiheuttaa huolta erityisesti tietokonetomografiatutkimusten (TT) lisääntymiseen liittyen. Tavanomaisia röntgentutkimuksia tehdään kuitenkin edelleen määrällisesti eniten. Lannerangan röntgentutkimus on yksi korkea-annoksisimmista ja siinä säteily kohdistuu säteilyherkille alueille. Kuvantamistutkimusten lähettämissuositukset on kehitetty tukemaan lähettäviä lääkäreitä sopivan ja oikeutetun tutkimuksen valitsemisessa. Tämän tutkimuksen tarkoitus oli seurata lähettämissuositusten ja koulutuksen vaikutusta kuvantamismääriin ja oikeutukseen nuorten TT-tutkimusten ja lannerangan röntgentutkimusten suhteen Oulun yliopistollisessa sairaalassa ja aikuisten rangan röntgentutkimusten suhteen perusterveydenhuollossa. Lisäksi tarkoitus oli selvittää, onko lähettämissuositusten vastaisissa lannerangan röntgentutkimuksissa merkittäviä kuvantamislöydöksiä. Nuorten TT-tutkimusten määrä aleni tilastollisesti merkitsevästi lannerangan (-80 %), kaularangan (-48 %) ja pään (-21 %) TT-tutkimuksissa. Myös rangan röntgentutkimusten määrä laski merkitsevästi: lannerangan röntgentutkimukset vähenivät yliopistosairaalassa 37 % ja rangan röntgentutkimukset perusterveydenhuollossa 51 %. Oikeutettujen tutkimusten osuus lisääntyi tai pysyi ennallaan. Nuorten oikeutettujen TT-tutkimusten osuus kasvoi merkitsevästi, 71 %:sta 87 %:iin. Myös lannerangan TT-tutkimusten oikeutus yliopistosairaalassa ja lannerangan röntgentutkimusten oikeutus sekä yliopistosairaalassa että perusterveydenhuollossa parantui merkitsevästi. Oikeutettujen rangan röntgentutkimusten osuus oli kuitenkin yllättävän alhainen perusterveydenhuollossa vielä toimenpiteiden jälkeenkin. Merkittäviä löydöksiä oli merkitsevästi enemmän niissä lannerangan röntgentutkimuksissa, jotka olivat lähettämissuositusten mukaisia. Lähettämissuositukset ja koulutus voivat vähentää säteilylle altistavien tutkimusten määrää ja parantaa tutkimusten oikeutusta merkitsevästi. Jatkuva seuranta ja kouluttaminen ovat kuitenkin tarpeen.

Background Prospective studies investigating risk factors for low back pain (LBP) in youth athletes are limited. The aim of this prospective study was to investigate the association between hip-pelvic kinematics and vertical ground reaction force (vGRF) during landing tasks and LBP in youth floorball and basketball players. Methods Three-hundred-and-eighty-three Finnish youth female and male floorball and basketball players (mean age 15.7 ± 1.8) participated and were followed up on for 3 years. At the beginning of every study year the players were tested with a single-leg vertical drop jump (SLVDJ) and a vertical drop jump (VDJ). Hip-pelvic kinematics, measured as femur-pelvic angle (FPA) during SLVDJ landing, and peak vGRF and side-to-side asymmetry of vGRF during VDJ landing were the investigated risk factors. Individual exposure time and LBP resulting in time-loss were recorded during the follow-up. Cox’s proportional hazard models with mixed effects and time-varying risk factors were used for analysis. Results We found an increase in the risk for LBP in players with decreased FPA during SLVDJ landing. There was a small increase in risk for LBP with a one-degree decrease in right leg FPA during SLVDJ landing (HR 1.09, 95% CI 1.02 to 1.17, per one-degree decrease of FPA). Our results showed no significant relationship between risk for LBP and left leg FPA (HR 1.04, 95% CI 0.97 to 1.11, per one-degree decrease of FPA), vGRF (HR 1.83, 95% CI 0.95 to 3.51) or vGRF side-to-side difference (HR 1.22, 95% CI 0.65 to 2.27) during landing tasks. Conclusions Our results suggest that there is an association between hip-pelvic kinematics and future LBP. However, we did not find an association between LBP and vGRF. In the future, the association between hip-pelvic kinematics and LBP occurrence should be investigated further with cohort and intervention studies to verify the results from this investigation. Level of evidence Prognosis, level 1b.

(1) Background: Assessments of intervertebral disc (IVD) changes, and IVD tissue adaptations due to physical activity, for example, remains challenging. Newer magnetic resonance imaging techniques can quantify detailed features of the IVD, where T2-mapping and T2-weighted (T2w) and Dixon imaging are potential candidates. Yet, their relative utility has not been examined. The performances of these techniques were investigated to characterize IVD differences in asymptomatic individuals with distinct physical activity histories. (2) Methods: In total, 101 participants (54 women) aged 25&ndash, 35 years with distinct physical activity histories but without histories of spinal disease were included. T11/12 to L5/S1 IVDs were examined with sagittal T2-mapping, T2w and Dixon imaging. (3) Results: T2-mapping differentiated Pfirrmann grade-1 from all other grades (p &lt, 0.001). Most importantly, T2-mapping was able to characterize IVD differences in individuals with different training histories (p &lt, 0.005). Dixon displayed weak correlations with the Pfirrmann scale, but presented significantly higher water content in the IVDs of the long-distance runners (p &lt, 0.005). (4) Conclusions: Findings suggested that T2-mapping best reflects IVD differences in asymptomatic individuals with distinct physical activity histories changes. Dixon characterized new aspects of IVD, probably associated with IVD hypertrophy. This complementary information may help us to better understand the biological function of the disc.

The aim of this study was to investigate the incidence of back pain in young basketball and floorball players under 21 years of age. The secondary aim was to examine risk factors especially for low back pain (LBP). Nine basketball and nine floorball teams (n = 396) participated in this prospective follow‐up study (2011‐2014). Young athletes (mean age 15.8 ± 1.9) performed physical tests and completed a questionnaire at baseline. The follow‐up lasted 1‐3 years per player. During the follow‐up, back pain reported by the players was registered on a weekly basis and verified by a study physician. The exposure time (AE) on team practices and games was recorded by the coach. Altogether back pain was reported 61 times by 51 players. The incidence of back pain was 87 per 1000 athlete‐years and 0.4 per 1000 hours of AE. Hamstrings, quadriceps and iliopsoas extensibility and general joint hypermobility were not associated with LBP. Furthermore, no association between LBP and leg extension strength or isometric hip abduction strength asymmetry was found in these young basketball and floorball players. In conclusion, back pain can lead to a considerable time‐loss from training and competition among young basketball and floorball players and the pain tends to reoccur. Lower extremity muscle extensibility, general joint hypermobility or investigated lower extremity strength measures were not associated with the risk of LBP. peerReviewed

Astronauts are at increased risk of spine injury. With a view to developing training approaches for the muscles of the spine in microgravity, this study examined the effects of axial loading and postural cues on the contraction of transversus abdominis and lumbar multifidus in supine lying using a novel exercise device (GravityFit). Thirty (18 males and 12 females) endurance-trained runners without a history of spinal pain aged 33–55 years were recruited. Magnetic resonance imaging (MRI) was performed under one rest and five exercise conditions, which involved variations in axial loading and postural cues. Whole volume of the abdominal and lumbar paraspinal muscles was imaged and transversus abdominis thickness and length and multifidus anteroposterior and mediolateral thickness measured. Transversus abdominis contraction was greatest in the ‘stretch tall plus arm extension’ (length, − 15%, P

Background context Muscle, bone and tendon respond anabolically to mechanical forces. Whether the intervertebral disc (IVD) can benefit from exercise is unclear. Purpose To examine whether exercise can beneficially affect IVD characteristics. Study design/setting This is a single-blinded 6-month randomised controlled trial (ACTRN12615001270505) in an exercise and physiotherapy clinic. Patient sample Forty patients with chronic non-specific low back pain (NSCLBP) are included in this study. Outcome measures The primary outcome was lumbar IVD T2 time (MRI). Secondary outcomes included IVD diffusion coefficient and IVD expansion with short-duration lying. Methods Twenty patients progressively loaded their lumbar IVDs (exercise) via an exercise programme involving progressive upright aerobic and resistance exercises targeting the trunk and major muscle groups and were compared to twenty patients who performed motor control training and manual therapy (control). Testing occurred at baseline, 3 months and 6 months. Results Seventeen exercise and fifteen control patients completed the interventions. There were no group-by-time differences in T2 time of the entire IVD (exercise 94.1 ± 10.0 ms vs. control 96.5 ± 9.3 ms, p = 0.549). Exercise patients had shorter T2 time in the posterior annulus at 6 months (82.7 ± 6.8 ms vs. 85.1 ± 8.0 ms, p = 0.028). Exercise patients showed higher L5/S1 apparent diffusion coefficients and decreased IVD height at 3 months (both p ≤ 0.050). After adjustments for multiple comparisons, differences lost statistical significance. Per-protocol and intent-to-treat analyses yielded similar findings. Conclusions This trial found that 6 months of exercise did not benefit the IVD of people with NSCLBP. Based on this index study, future studies could investigate the effect of exercise on IVD in different populations, with different types, durations and/or intensities of exercise, and using different IVD markers. peerReviewed

Background The thoracic spine (TS) has been neglected in the study of the spine despite its essential role in the stability and posture of the entire spinal complex. Therefore, there is an inevitable need to investigate the reproducibility of different thoracic spinal posture measures used in subjects with TS pain. Methods Thirty-two subjects (16 females and 16 males, mean age 39 years) were evaluated by two physiotherapists on the same day to gauge inter-rater reliability and on two consecutive days to gauge intra-rater reliability. TS posture was assessed by observation, and thoracic spine mobility was measured by manual assessment of segmental flexion and extension mobility in a seated position. Additionally, posterior-to-anterior accessory mobility in a prone position was assessed manually. Moreover, cervicothoracic flexion in a seated position, thoracic posture, and thoracic flexion and extension mobility in a standing position were assessed with a tape measure, and flexion and extension mobility in a seated position and TS posture in seated and standing positions were measured with an inclinometer. The intraclass correlation coefficient (ICC), standard error of measurement (SEM), mean difference (MD), Bland-Altman (B&A) plot features and coefficient of repeatability (CR) were calculated. Results The mean and standard deviation (SD) of the duration of TS pain was 22 (SD 45) months, with the intensity of pain being rated at 27 (SD 21) mm on a visual analogue scale (VAS). Intra-rater reliability was very strong (ICC ≥ 0.80) for the evaluation of seated and standing upper TS posture, standing whole TS posture and seated lower TS posture with an inclinometer. Moreover, TS posture evaluation with a measuring tape, posture inspection in a seated position, and manual assessment of segmental extension were found to have very strong intra-rater reliability. Inter-rater reliability was very strong for inclinometer measurements of standing and seated upper TS posture as well as standing whole TS posture. Conclusion Intra-rater reliability was higher than inter-rater reliability in most of the evaluated measurements. Overall, posture measurements with an inclinometer were more reliable than mobility measurements with the same instrument. The manual assessments can be used reliably when same evaluator performs the examination. Trial registration Clinical Trials, NCT01884818. Registered 24 June 2013, https://clinicaltrials.gov/ct2/show/NCT01884818?cond=thoracic+spine&cntry=FI&rank=1

Exercise and spinal manipulative therapy are commonly used for the treatment of chronic low back pain (CLBP) in Australia. Reduction in pain intensity is a common outcome, however, it is only one measure of intervention efficacy in clinical practice. Therefore, we evaluated the effectiveness of two common clinical interventions on physical and self-report measures in CLBP. Participants were randomized to a 6‑month intervention of general strength and conditioning (GSC, n = 20, up to 52 sessions) or motor control exercise plus manual therapy (MCMT, n =20, up to 12 sessions). Pain intensity was measured at baseline and fortnightly throughout the intervention. Trunk extension and flexion endurance, leg muscle strength and endurance, paraspinal muscle volume, cardio‑respiratory fitness and self-report measures of kinesiophobia, disability and quality of life were assessed at baseline and 3- and 6-month follow-up. Pain intensity differed favoring MCMT between-groups at week 14 and 16 of treatment (both, p = 0.003), but not at 6-month follow‑up. Both GSC (mean change (95%CI): &minus, 10.7 (&minus, 18.7, &minus, 2.8) mm, p = 0.008) and MCMT (&minus, 19.2 (&minus, 28.1, &minus, 10.3) mm, p &lt, 0.001) had within-group reductions in pain intensity at six months, but did not achieve clinically meaningful thresholds (20mm) within- or between‑group. At 6-month follow-up, GSC increased trunk extension (mean difference (95% CI): 81.8 (34.8, 128.8) s, p = 0.004) and flexion endurance (51.5 (20.5, 82.6) s, p = 0.004), as well as leg muscle strength (24.7 (3.4, 46.0) kg, p = 0.001) and endurance (9.1 (1.7, 16.4) reps, p = 0.015) compared to MCMT. GSC reduced disability (&minus, 5.7 (‑11.2, &minus, 0.2) pts, p = 0.041) and kinesiophobia (&minus, 6.6 (&minus, 9.9, &minus, 3.2) pts, 0.001) compared to MCMT at 6‑month follow-up. Multifidus volume increased within-group for GSC (p = 0.003), but not MCMT or between-groups. No other between-group changes were observed at six months. Overall, GSC improved trunk endurance, leg muscle strength and endurance, self-report disability and kinesiophobia compared to MCMT at six months. These results show that GSC may provide a more diverse range of treatment effects compared to MCMT.

Purpose: Interleukin 6 (IL-6) and the acute phase C-reactive protein (CRP) blood concentrations after lumbar spine fusion may be affected by age. The purpose of this prospective observational study was to assess postoperative serum levels of pro-inflammatory IL-6 and CRP after instrumented lumbar spine fusion surgery. We hypothesized that older patients would have increased levels of IL-6 and CRP after surgery. Methods: IL-6 and high-sensitive CRP biochemical marker levels were measured before instrumented spinal fusion, and postoperatively at 1 and 3 days, 6 weeks, and 3 months. The 49 patients in this sample were divided into two groups: age ≤ 60 years (n = 23) and age > 60 years (n = 26). Results: Acute changes in IL-6 high-sensitivity and CRP from preoperative levels to postoperative day (POD) 1 increased with age. Mean (95% CI) difference between the age-groups in changes of IL-6 at PODs 1 and 3 was 45 pg/ml (10–83, p = 0.014) and 20 pg/ml (5–36, p = 0.021), respectively. Mean (95% CI) difference between groups in changes of CRP at PODs 1 and 3 was 9.6 mg/l (−3.5 to 22.7, p = 0.47) and 24.8 mg/l (−17 to 67, p = 0.33), respectively. Both groups had decreased IL-6 and CRP levels at 6 weeks after surgery compared to the preoperative level. Conclusions: Elevation of IL-6 and CRP is stronger in patients over 60 years old after instrumented lumbar spinal fusion. The CRP and IL-6 are sensitive markers for acute postoperative inflammation. Even high acute CRP values do not necessarily indicate postoperative infection. peerReviewed

Objective: The aim of this study was to investigate changes in trunk muscle strength 12 months after lumbar spine fusion (LSF) compared to preoperative strength. Methods: A total of 194 patients (mean ± standard deviation [SD] age, 61 ± 21 years) who underwent LSF participated in this prospective longitudinal study. Physical measurements of the participants were made before surgery and 12 months postoperatively. Isometric trunk extension and flexion strength was measured using a strain-gauge dynamometer in the standing position. Strength changes were calculated. Regression analysis was performed to explore which factors predicted strength levels at 12 months postoperatively. Results: The preoperative mean ± SD extension strength was 205 ± 144 N, which increased to 258 ± 142 N (p < 0. 001) at the 12-month follow-up. Flexion strength increased from 295 ± 172 N to 364 ± 164 N (p < 0. 001). The preoperative extension/flexion strength ratio was 0.75 ± 0.38 and remained similar (0.73 ± 0.26) at 12 months postoperatively (p = 0.39). Conclusion: Although trunk muscle strength increased by 26% for extension and 23% for flexion at the 12-month postoperative follow-up, both values remained objectively low. In addition, flexion strength remained higher than extension strength, which indicates an imbalance between those muscle groups. Age, severe back pain, and low trunk muscle strength before surgery predicted low trunk muscle strength at 1 year after spinal fusion.

Osteoporotic vertebral fractures are common among ageing populations worldwide. Although small vertebral size has been established as an independent risk factor for vertebral fracturing, relatively few determinants of vertebral size are currently known. The present study aimed to reveal lifetime factors that associate with midlife vertebral size. Overall physical activity across the lifespan, sports participation in adulthood, occupational physical activities in adulthood, and physical growth in early life were investigated. A subsample of the Northern Finland Birth Cohort Study 1966 was used, with a 46-year follow-up (n = 1,540). Vertebral dimensions were obtained by magnetic resonance imaging of the lumbar spine at the age of 46. The present data showed that high lifelong leisure-time physical activity and active participation in high-impact sports in adulthood were associated with large midlife vertebral size among women, but no such association was detected among men. Occupational physical activities were not associated with vertebral size among either sex. Early-life weight gain predicted large midlife vertebrae among both sexes, and the effect of height gain on vertebral size seemed to be mediated by adult height. The present findings show that the female vertebra in particular seems to benefit from high leisure-time physical activity and active participation in high-impact sports. Regardless of sex, early development also seems to play a role in determining later-life vertebral size. Prospective studies should confirm the causality of the present findings, and further research is needed to shed light on other lifetime factors as determinants of vertebral size. Tiivistelmä Selkänikaman osteoporoottiset murtumat ovat maailmanlaajuisesti yleinen ikääntyvän väestön vaiva. Pienen nikamakoon tiedetään lisäävän nikamamurtuman riskiä, mutta nikamakokoon vaikuttavia tekijöitä tunnetaan toistaiseksi varsin vähän. Tämän tutkimuksen tavoitteena on selvittää keski-iän nikamakokoon vaikuttavia elinaikaisia tekijöitä. Erityisesti tutkitaan vapaa-ajan liikunnallisuuden, lajikohtaisen harrastusaktiivisuuden, työn liikunnallisten piirteiden sekä lapsuuden ja nuoruuden fyysisen kehityksen yhteyttä nikamakokoon. Tutkimusjoukkona käytetään osaotosta Pohjois-Suomen vuoden 1966 syntymäkohortista (n = 1 540). Seuranta-aika on ollut 46 vuotta, ja selkänikaman koko on määritetty tutkittavista 46 vuoden iässä otetuista lannerangan magneettikuvista. Tutkimusaineistossa naisten elinaikainen vapaa-ajan liikunnallisuus sekä aktiivinen luustoa kuormittavien liikuntalajien harrastaminen ovat yhteydessä suureen nikamakokoon keski-iässä. Miesten liikunnallisuuden ja nikamakoon välillä ei sen sijaan havaittu vastaavaa yhteyttä, eivätkä työn liikunnalliset piirteet olleet yhteydessä nikamakokoon kummallakaan sukupuolella. Varhainen painon kasvu ennusti suurta keski-iän nikamakokoa sukupuolesta riippumatta, ja varhaisen pituuskasvun vaikutus nikamakokoon näytti välittyvän aikuispituuden kautta. Tutkimuksen tulosten perusteella siis erityisesti naiset näyttäisivät hyötyvän vapaa-ajan liikunnallisesta aktiivisuudesta ja luuta kuormittavien lajien harrastamisesta aikuisiällä. Sukupuolesta riippumatta myös lapsuuden ja nuoruuden fyysisellä kehityksellä näyttäisi olevan merkitystä keski-iän nikamakokoon. Tulevaisuudessa prospektiivisten tutkimusasetelmien tulisi vahvistaa tässä tutkimuksessa havaittujen yhteyksien kausaliteetti. Lisäksi tutkimusta tarvittaisiin jatkossa muiden nikamakokoon vaikuttavien elinaikaisten tekijöiden selvittämiseksi.