Increase In Leg Length Research Articles

Is adult gait less susceptible than paediatric gait to hip joint centre regression equation error?

Hip joint centre (HJC) regression equation error during paediatric gait has recently been shown to have clinical significance. In relation to adult gait, it has been inferred that comparable errors with children in absolute HJC position may in fact result in less significant kinematic and kinetic error. This study investigated the clinical agreement of three commonly used regression equation sets (Bell et al., Davis et al. and Orthotrak) for adult subjects against the equations of Harrington et al. The relationship between HJC position error and subject size was also investigated for the Davis et al. set. Full 3-dimensional gait analysis was performed on 12 healthy adult subjects with data for each set compared to Harrington et al. The Gait Profile Score, Gait Variable Score and GDI-kinetic were used to assess clinical significance while differences in HJC position between the Davis and Harrington sets were compared to leg length and subject height using regression analysis. A number of statistically significant differences were present in absolute HJC position. However, all sets fell below the clinically significant thresholds (GPS <1.6°, GDI-Kinetic <3.6 points). Linear regression revealed a statistically significant relationship for both increasing leg length and increasing subject height with decreasing error in anterior/posterior and superior/inferior directions. Results confirm a negligible clinical error for adult subjects suggesting that any of the examined sets could be used interchangeably. Decreasing error with both increasing leg length and increasing subject height suggests that the Davis set should be used cautiously on smaller subjects.

Wave pressure acting on V-shaped floating breakwater in random seas

Wave pressure on the wet surface of a V-shaped floating breakwater in random seas is investigated. Considering the diffraction effect, the unit velocity potential caused by the single regular waves around the breakwater is solved using the finite-depth Green function and boundary element method, in which the Green function is solved by integral method. The Response-Amplitude Operator (RAO) of wave pressure is acquired according to the Longuet-Higgins' wave model and the linear Bernoulli equation. Furthermore, the wave pressure's response spectrum is calculated according to the wave spectrum by discretizing the frequency domain. The wave pressure's characteristic value corresponding to certain cumulative probability is determined according to the Rayleigh distribution of wave heights. The numerical results and field test results are compared, which indicates that the wave pressure calculated in random seas agrees with that of field measurements. It is found that the bigger angle between legs will cause the bigger pressure response, while the increase in leg length does not influence the pressure significantly. The pressure at the side of head sea is larger than that of back waves. When the incident wave angle changes from 0A degrees to 90A degrees, the pressure at the side of back waves decreases clearly, while at the side of head sea, the situation is more complicated and there seems no obvious tendency. The concentration of wave energy around low frequency (long wavelength) will induce bigger wave pressure, and more attention should be paid to this situation for the structure safety.

Scaling of sensorimotor control in terrestrial mammals

Sensorimotor control is greatly affected by two factors--the time it takes for an animal to sense and respond to stimuli (responsiveness), and the ability of an animal to distinguish between sensory stimuli and generate graded muscle forces (resolution). Here, we demonstrate that anatomical limitations force a necessary trade-off between responsiveness and resolution with increases in animal size. To determine whether responsiveness is prioritized over resolution, or resolution over responsiveness, we studied how size influences the physiological mechanisms underlying sensorimotor control. Using both new electrophysiological experiments and existing data, we determined the maximum axonal conduction velocity (CV) in animals ranging in size from shrews to elephants. Over the 100-fold increase in leg length, CV was nearly constant, increasing proportionally with mass to the 0.04 power. As a consequence, larger animals are burdened with relatively long physiological delays, which may have broad implications for their behaviour, ecology and evolution, including constraining agility and requiring prediction to help control movements.

Learning Curve Analysis of the Collum Femoris Preserving Total Hip Surgical Technique

The aim of this study was to determine whether femoral neck preserving total hip arthroplasty would become less difficult and more efficient during the first 20 cases and to identify potential pitfalls during the introduction of this procedure. The difficulty and efficiency of the initial 20 procedures performed by four surgeons was prospectively determined by analysing a total of 68 video recordings using time-action analysis. This method measures the duration and efficiency of individual actions needed for a surgeon to achieve his or her goal. Afterwards, we reviewed all actions with a long duration and discussed possible causes of delay with the surgeons to identify possible pitfalls. We found a decrease of difficulty and an increase of efficiency during the first 20 cases and a more consistent execution after the initial five cases. Estimating the correct osteotomy level and stem curvature was often difficult, which resulted in a variable stem position. Radiologic analysis demonstrated a tendency for varus position and increased leg length throughout the series, even after the surgeons demonstrated technical proficiency.

The influence of leg length difference on clinical outcome after revision TKA

BackgroundThe purpose of this paper was to document the incidence of leg length changes after revision total knee arthroplasty (TKA) and its effect on clinical outcome. MethodsLeg length difference (LLD) was prospectively measured in 85 patients using digital standing full leg radiography before and after revision TKA. Additionally the patient's subjective perception of LLD was assessed postoperatively. Linear regression models were used to study the correlation between each of these parameters and the clinical outcome after 1year. Clinical outcome was evaluated by means of the Knee Society Score (KSS). ResultsRevision TKA resulted on average in an increased leg length of 5.3mm. Sixty-five legs (76%) were lengthened with the procedure, 17 (20%) were shortened and three (4%) remained of identical length. Increased leg length after revision was positively correlated with clinical outcome at 3months (Spearman r=0.22, p=0.044) and 1year (Spearman r=0.26, p=0.027). The evidence for this correlation remained after correction for age, gender and diagnosis (p=0.012). The most important contributors to improved clinical outcome scores were improved pain score (Spearman r=0.19, p=0.09) and increased stability (Spearman r=0.13, p=0.24), rather than range of motion (Spearman r=−0.02, p=0.85). ConclusionsThe results from our work indicate that revision TKA tends to lengthen the leg by approximately 5mm. Contrary to what might be expected, leg lengthening after revision TKA is correlated with improved clinical outcome. Level of evidenceLevel 2b.

Intramedullary Skeletal Kinetic Distractor in the Treatment of Leg Length Discrepancy—A Review of 16 Cases and Analysis of Complications

The intramedullary skeletal kinetic distractor (ISKD; Orthofix) is a relatively new device available for limb lengthening. This fully implantable mechanical nail promises reduced morbidity over traditional methods where external fixation is used. We report on our experience using this device in treating 16 patients with leg length discrepancy. Retrospective review of 16 consecutive patients treated with ISKD. Tertiary trauma hospital. Thirteen males and 3 females were treated with the ISKD between 2004 and 2009. There were 11 femora and 5 tibiae. The indication for lengthening was posttraumatic shortening in 15 patients and congenital hypoplasia in the remaining patient. Limb length gained, rate of lengthening, time to consolidation, complications, and factors that may be associated with complications. All patients in the series successfully completed treatment and reached the desired limb length with radiographic evidence of consolidation. The average leg length increase was 35 mm (21-75 mm). No infection, malunion, or joint contracture was observed. A length of less than 100 mm of the thick portion of the nail in the distal fragment is associated with the likelihood of a "runaway nail" (distraction index > 1.5 mm/d). Six patients had poor regenerate requiring bone grafting. Likelihood of poor regenerate was associated with number of previous operations on the lengthened bone. Three patients had nails that were difficult to distract and required closed manipulation under anesthesia. The ISKD is an effective method for correcting leg length discrepancies. Complications are frequent but are manageable with standard techniques. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Leg length, sitting height and postmenopausal breast cancer risk

Background:Tallness has consistently been associated with an increased risk of breast cancer. We investigated the association further by decomposing height into leg length and sitting height.Methods:From the prospective Danish cohort ‘Diet, Cancer and Health’, 23 864 postmenopausal women enrolled during 1993–1997 were followed for a diagnosis of breast cancer in the Danish Cancer Registry through 2009.Results:The incidence rate ratios for breast cancer were 1.11 (95% CI=1.06–1.16) for each 5 cm increase in total height and 1.09 (95% CI=1.01–1.17) and 1.14 (95% CI=1.04–1.25) for each 5 cm increase in leg length and sitting height, respectively. There was no statistical significant difference between the associations for leg length and sitting height (P=0.47).Conclusion:Leg length does not seem to be more strongly associated with breast cancer among postmenopausal women than sitting height.

Understanding selection for long necks in different taxa

There has been recent discussion about the evolutionary pressures underlying the long necks of extant giraffes and extinct sauropod dinosaurs. Here we summarise these debates and place them in a wider taxonomic context. We consider the evolution of long necks across a wide range of (both living and extinct) taxa and ask whether there has been a common selective factor or whether each case has a separate explanation. We conclude that in most cases long necks can be explained in terms of foraging requirements, and that alternative explanations in terms of sexual selection, thermoregulation and predation pressure are not as well supported. Specifically, in giraffe, tortoises, and perhaps sauropods there is likely to have been selection for high browsing. It the last case there may also have been selection for reaching otherwise inaccessible aquatic plants or for increasing the energetic efficiency of low browsing. For camels, wading birds and ratites, original selection was likely for increased leg length, with correlated selection for a longer neck to allow feeding and drinking at or near substrate level. For fish-eating long-necked birds and plesiosaurs a small head at the end of a long neck allows fast acceleration of the mouth to allow capture of elusive prey. A swan's long neck allows access to benthic vegetation, for vultures the long neck allows reaching deep into a carcass. Geese may be an unusual case where anti-predator vigilance is important, but so may be energetically efficient low browsing. The one group for which we feel unable to draw firm conclusions are the pterosaurs, this is in keeping with the current uncertainty about the biology of this group. Despite foraging emerging as a dominant theme in selection for long necks, for almost every taxonomic group we have identified useful empirical work that would increase understanding of the selective costs and benefits of a long neck.

Perception of Imposed Leg Length Inequality in Normal Subjects

Lower limb length differences of up to 10mm exist in 60% - 95% of the population.There are usually no symptoms or functional effects. Following Total Hip Arthroplasty (THA), satisfactory clinical results can be spoiled by dissatisfaction due to a change in leg length. Although the change in leg length may be modest in comparison to the normal variation, the patient may perceive this as a leg length discrepancy. To study the average threshold for perception, artificial leg length discrepancies of 5 mm to 25 mm were created in 30 young healthy adults using calibrated wooden blocks. Responses were recorded and analysed using a chi-squared test for independence and an independent measures t-test. Awareness of leg length discrepancy was related to the magnitude of the discrepancy (X2 (15)= 156.6, p<0.05 on the right side, and X2 (15)= 178.725 p<0.05 on the left side). It was shown that no subject reported a 5mm increase in leg length to be uncomfortable while all subjects were aware of leg length discrepancies of 20 mm and 25 mm. When there was a discrepancy of 10 mm in either lower limb, 29 out of 30 subjects (96.7%) thought there was a difference in leg length. Consequently it is suggested that during total hip arthroplasty the surgeon should aim for a leg length discrepancy of less than 10 mm.

Klinefelter syndrome: clinical and molecular aspects

Klinefelter syndrome is the most common chromosome abnormality in humans. The estimated prevalence is one in 500 to one in 1000 males but due to the widely variable and often aspecific features, only one in four cases are recognized. The most specific clinical features which can be observed at adult age are small testes, gynecomastia, female distribution of fat and body hair, slightly increased body length due to an increased leg length and azoospermia. Cognition is characterized by verbal deficits and psychosocial features include autistiform behavior. Structural brain abnormalities have been observed by MRI, such as decreased brain volumes and a decrease of asymmetry in areas corresponding to language performance. In the vast majority of cases a non-mosaic 47,XXY karyotype is observed. Parental imprinting of the extra X chromosome, variable inactivation of some X-chromosomal genes and CAG repeat length polymorphism of the androgen receptor may all be related to the variability of the phenotype. Surgical procedures of obtaining sperm in combination with repeated intracytoplasmic sperm injection/in vitro fertilization treatment may allow up to one in four men with Klinefelter syndrome to father children.

Scaling of sensorimotor control in terrestrial mammals

Sensorimotor control is greatly affected by two factors--the time it takes for an animal to sense and respond to stimuli (responsiveness), and the ability of an animal to distinguish between sensory stimuli and generate graded muscle forces (resolution). Here, we demonstrate that anatomical limitations force a necessary trade-off between responsiveness and resolution with increases in animal size. To determine whether responsiveness is prioritized over resolution, or resolution over responsiveness, we studied how size influences the physiological mechanisms underlying sensorimotor control. Using both new electrophysiological experiments and existing data, we determined the maximum axonal conduction velocity (CV) in animals ranging in size from shrews to elephants. Over the 100-fold increase in leg length, CV was nearly constant, increasing proportionally with mass to the 0.04 power. As a consequence, larger animals are burdened with relatively long physiological delays, which may have broad implications for their behaviour, ecology and evolution, including constraining agility and requiring prediction to help control movements.

Präoperative Planung und Rekonstruktion in der primären Hüftendoprothetik mit und ohne modularen Hals

Preoperative planning is regarded as an important requirement for successful implantation of a hip replacement. One of the crucial aspects of planning is the restoration of the normal anatomy of the hip as this increases the chances for good clinical function and reduces wear debris. Various systems for restoration of the hip are available including stem systems with different stem sizes and offsets and so-called modular stem systems which have the additional possibility of adjusting the neck length and angle. The aim of this study was to investigate to what extent a good postoperative outcome can be achieved using a modular and a non-modular stem system in comparison with preoperative planning. Furthermore, the study assessed the difference between preoperative planning carried out by a senior surgeon and by an assistant surgeon. Standard preoperative and postoperative digitalised radiographs with an anteroposterior view of the pelvis centred over the pubic symphysis were made. Preoperative planning aimed for exact reconstruction of offset and equal leg length. Preoperative planning and evaluation of the postoperative outcome were performed by digitalised image-analysing software. The symptom-free contralateral hip served as reference for anatomic reconstruction. The postoperative results confirmed the preoperative planning. The preoperative planning was successfully implemented with both systems. Postoperatively, we observed a slightly reduced offset (Group 1: 3.6 mm, Group 2: 3.54 mm) and an increase in leg length of less than 5 mm in both groups. There was no significant difference between the preoperative planning carried out by the senior surgeon and the assistant surgeon. Implementation of preoperative planning with both the modular and the non-modular system was very satisfactory. It was irrelevant if the planning was carried out by a senior surgeon or by an assistant surgeon in the first year of training.

Relationship between vertical jumping performance and anthropometric characteristics during growth in boys and girls

The aim of the study was to compare vertical jumping performances in boys and girls during growth. The maximum heights attained in a countermovement jump (CMJ) and squat jump (SJ) were measured using an Ergojump Bosco System. Average power output (PO) was recorded, and percentage of fast-twitch (%FT) muscle fiber distribution was estimated during the rebound jump. Differences in the maximum CMJ and SJ (CMJ-SJ) heights were calculated. Regressions between PO and age, lean body mass (LBM), and leg muscle volume (LMV), respectively, were computed for 240 boys and 239 girls (aged 11-16 years). Height, LMV, and body mass values were larger in boys than girls aged 14 years. Both groups had a similar body mass index independently of age. The CMJ, SJ, PO, and %FT were larger in boys than in girls between 12 and 16 years of age. Strong correlations were found between PO and age in the population as a whole, and between PO and LBM, PO and LMV in each group. The CMJ-SJ decreased with increasing age in both groups without significant differences. Conclusion Jumping performance increases during growth, with gender differences manifesting from 14 years onwards due to the much greater increase in leg length and LMV in boys than in girls.

Adaptive preferences for leg length in a potential partner

It has been shown that height is one of the morphological traits that influence a person's attractiveness. To date, few studies have addressed the relationship between different components of height and physical attractiveness. Here, we study how leg length influences attractiveness in men and women. Stimuli consisted of seven different pictures of a man and seven pictures of a woman in which the ratio between leg length and height was varied from the average phenotype by elongating and shortening the legs. One hundred men and 118 women were asked to assess the attractiveness of the silhouettes using a seven-point scale. We found that male and female pictures with shorter than average legs were perceived as less attractive by both sexes. Although longer legs appeared to be more attractive, this was true only for the slight (5%) leg length increase; excessively long legs decreased body attractiveness for both sexes. Because leg length conveys biological quality, we hypothesize that such preferences reflect the workings of evolved mate-selection mechanisms. Short and/or excessively long legs might indicate maladaptive biological conditions such as genetic diseases, health problems, or weak immune responses to adverse environmental factors acting during childhood and adolescence.

Skeletal strain patterns and growth in the emu hindlimb during ontogeny

Most studies examining changes in mechanical performance in animals across size have typically focused on inter-specific comparisons across large size ranges. Scale effects, however, can also have important consequences in vertebrates as they increase in size and mass during ontogeny. The goal of this study was to examine how growth and development in the emu (Dromaius novaehollandiae) hindlimb skeleton reflects the demands placed upon it by ontogenetic changes in locomotor mechanics and body mass. Bone strain patterns in the femur and tibiotarsus (TBT) were related to ontogenetic changes in limb kinematics, ground reaction forces, and ontogenetic scaling patterns of the cross-sectional bone geometry, curvature and mineral ash content over a 4.4-fold increase in leg length and 65-fold increase in mass. Although the distribution of principal and axial strains remained similar in both bones over the ontogenetic size range examined, principal strains on the cranial femur and caudal femur and TBT increased significantly during growth. The ontogenetic increase in principal strains in these bones was likely caused by isometry or only slight positive allometry in bone cross-sectional geometry during growth, while relative limb loading remained similar. The growth-related increase in bone strain magnitude was likely mitigated by increased bone mineralization and decreased curvature. Throughout most of ontogeny, shear strains dominated loading in both bones. This was reflected in the nearly circular cross-sectional geometry of the femur and TBT, suggesting selection for resistance to high torsional loads, as opposed to the more eccentric cross-sectional geometries often associated with the bending common to tetrapods with parasagittal limb orientations, for which in vivo bone strains have typically been measured to date.

Morphological and biochemical jumping adaptations in smaller grasshoppers

Many interspecific vertebrate studies have shown that similarly shaped animals have isometric proportions of muscle mass and leg length, and equivalent jumping performance. In contrast, ontogenetic grasshopper studies have shown that older grasshoppers have disproportionally longer legs, produce more lactate during jumping, and jump more body lengths. In this study, we compared the morphology, jump performance and lactate production of twenty species of female grasshoppers ranging in size from 0.2 to 7.0 g to determine whether interspecific scaling of jump performance followed vertebrate or ontogenetic grasshopper models. In contrast to both vertebrate and ontogenetic locust studies, we found that smaller grasshoppers had a 6-fold greater proportion of muscle mass and relatively longer hind legs. Although these morphological changes should result in improved performance, we found that body size did not affect jump distance or jump energy (either maximally or throughout the ten minute trial). Unlike the ontogeny study, smaller grasshoppers produced more lactate during jumping. Model calculations suggest that increased leg length, lactate production and muscle size are necessary for smaller grasshoppers to overcome a greater cost of drag and yet achieve similar jump distances. This work was partially supported by NSF IBN-9985857 and IOB-0419704 to JFH and IBN-0104959 to SDK and JFH.

Commentary: Proportion not the cause of beauty but of health?

Body proportions have come of age in the medical and epidemiological research communities. The article in this issue by Ferrie et al. 1 examines the association between leg length and trunk length to coronary heart disease (CHD) in the latest phase of the Whitehall II study, a prospective survey of the health of British civil servants. This is one of many studies published in the last decade to focus on the length of body segments in relation to health. Decomposing stature into its major components is proving to be a useful strategy to assess the antecedents of disease, morbidity, and death in adulthood. A concern with body proportion has deep roots in European history. In the 15th Century, Leonardo da Vinci developed canons (rules) for the representation of the human body proportion in art and Albrecht Durer devised technology to draw both the canonical forms and many variations as observed in nature. Edmund Burke, the British statesman and philosopher, published in 1756 the essay, The Philosophical Inquiry into the Origin of Our Ideas on the Sublime and Beautiful. One part of this is titled, ‘Proportion not the Cause of Beauty in the Human Species.’ Burke argued that people with body proportions outside the canon might still be considered beautiful. He held the human leg to be especially handsome, ‘I believe nobody will think the form of a man’s leg so well adapted to running, as those of a horse, a dog, a deer, and several other creatures; at least they have not that appearance: yet, I believe, a well-fashioned human leg will be allowed to far exceed all these in beauty.’ One is left to wonder which human legs are ‘well-fashioned.’ Perhaps Burke meant those that are relatively straight and long—contraindicating rickets, suggesting good health and nutrition in childhood, and predicting fecundity in adult women. Ferrie and colleagues report that leg length is inversely associated with CHD risk factors in middle-aged men and women. The strength of this finding would likely be increased had the authors used the sitting height ratio (SHR), calculated as (sitting height/stature · 100). The SHR provides a better account of body proportion variation standardized against total stature. In our research using data from the United States National Health and Examination Survey (1988–94) we find stronger correlations for SHR than leg length with body mass index and sum of skinfolds. Leitch 4 was, perhaps, the first medical researcher to propose that a ratio of leg length to total stature might be a good indicator of nutritional history and health. Noting the wellknown cephalo-caudal gradient in growth, Leitch (p. 145) wrote, ‘. . . it would be expected on general principles that children continuously underfed would grow into underdeveloped adults . . .with normal or nearly normal size head, moderately retarded trunk and relatively short legs.’ Reviewing the literature available at the time, Leitch found that improved nutrition during infancy and childhood did indeed result in a greater increase in leg length than in total height or weight. Longer-legged children were also less susceptible to bronchitis, which was then a scourge of poorly fed children. A recent spate of research on body proportions and health finds that poor nutrition and health during pregnancy and during the first 6 years of life post-partum result in fetuses, newborns, infants, and children of reduced body length, mostly due to reduced leg length. High risk behaviours, such as smoking during pregnancy, also reduce height and especially leg length of offspring. The alterations in body proportions are likely due to competition between body segments, such as trunk versus limbs, and organs for the limited nutrients during growth. 5

Insect Navigation: Measuring Travel Distance across Ground and through Air

Walking insects probably monitor leg movements to estimate how far they travel, whereas flying insects monitor optic flow.

Skin behavior during leg lengthening in patients with achondroplasia and hypochondroplasia: a short-term observation during leg lengthening

BackgroundAlthough distraction osteogenesis is a recently established method of limb lengthening, it is not well known how soft tissues behave during bone lengthening. Because skin is tissue that can be easily and directly observed, we analyzed skin extension during limb lengthening to study the condition of soft tissues. MethodWe examined three achondroplastic and two hypochondroplastic patients who underwent bilateral tibial lengthening with unilateral bone lengtheners. To analyze skin extension during leg lengthening, the bilateral skin surface was marked in a latticework pattern, starting 10cm proximal to the knee joint down to 10cm distal to the ankle joint, with black ink. The longitudinal length and the area of lattices, and the circumferential length of legs were measured. ResultsWe found that: (1) the longitudinal extension of the skin during leg lengthening occurs not only in the bone lengthening portion between fixator pins but also around the knee or ankle joints; (2) circumferential length of legs was decreased, and soft tissue volume also does not increase in proportion to the increase in leg length. Soft tissue volume started to increase in the central region of the legs after a 30% increase in leg length was obtained, resulting in the 10% increase in the volume at the end point. ConclusionsThese data suggest that soft tissue extension precedes soft tissue neogenesis at least during the initial period of leg lengthening, possibly based on its viscoelastic properties. After a 30% increase in leg length is obtained, soft tissue neogenesis takes place in the central region of the leg.

Milk as a food for growth? The insulin-like growth factors link

The mechanisms underlying the association of insulin-like growth factor-I (IGF-I) and leg length (a marker of prepubertal growth) with cancer risk are uncertain. One hypothesis is that diet in early childhood might provide the link. The aim of the present study was to examine the association between early diet - in particular, the intakes of cows' milk and dairy products - and height, leg length and IGF-I levels at age 7-8 years. Children participating in the Avon Longitudinal Study of Parents and Children. Diet was assessed using a 3-day unweighed food record. Anthropometry, IGF-I and insulin-like growth factor-binding protein-3 (IGFBP-3) were measured by standard methods. Data on both diet and height were available for 744 children (404 boys) and on diet and IGF for 538 (295 boys). After adjusting for energy, both cows' milk and dairy product intakes were positively associated with IGF-I (P=0.040 and 0.027, respectively) and IGFBP-3 levels (P=0.082 and 0.067, respectively). These associations persisted on adjustment for potential confounders, but were abolished on controlling for protein intake. In energy-adjusted models there was only weak evidence of associations of milk and dairy product intakes with anthropometry. In boys only, dairy product intake was positively associated with leg length (equivalent to a 0.058 (0.002, 0.114) standard deviation score increase in leg length per 100 g increase in daily intake). These data provide some evidence that variation in childhood milk and dairy product intakes underlies associations of leg length, IGF-I and cancer risk. The association appears to be due to the protein content of milk.