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Bone stress injuries (BSIs) frequently occur in the leg and foot long bones of female distance runners. A potential means of preventing BSIs is to participate in multidirectional sports when younger to build a more robust skeleton. The current cross-sectional study compared differences in tibia, fibula, and second metatarsal diaphysis size, shape, and strength between female collegiate-level athletes specialized in cross-country running (RUN, n = 16) and soccer (SOC, n = 16). Assessments were performed using high-resolution peripheral quantitative computed tomography and outcomes corrected for measures at the radius diaphysis to control for selection bias and systemic differences between groups. The tibia in SOC had a 7.5 % larger total area than RUN, with a 29.4 % greater minimum second moment of area (I MIN ) and 8.2 % greater estimated failure load (all p ≤ 0.02). Tibial values in SOC exceeded reference data indicating positive adaptation. In contrast, values in RUN were similar to reference data suggesting running induced limited tibial adaptation. RUN did have a larger ratio between their maximum second moment of area (I MAX ) and I MIN than both SOC and reference values. This suggests the unidirectional loading associated with running altered tibial shape with material distributed more in the anteroposterior (I MAX ) direction as opposed to the mediolateral (I MIN ) direction. Comparatively, SOC had a similar I MAX /I MIN ratio to reference data suggesting the larger tibia in SOC resulted from multiplane adaptation. In addition to enhanced size and strength of their tibia, SOC had enhanced structure and strength of their fibula and second metatarsal. At both sites, polar moment of inertia was approximately 25 % larger in SOC compared to RUN (all p = 0.03). These data support calls for young female athletes to delay specialization in running and participate in multidirectional sports, like soccer, to build a more robust skeleton that is potentially more protected against BSIs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The forced turnout has a perceived risk of development of hallux valgus (HV) in ballet dancers. We determined how the forced turnout affects the sagittal mobility of the first tarsometatarsal (TMT) joint, which is one of the pathogenic factors of HV development. Seventeen female ballet dancers (body mass index: 18.2 ± 1.8 kg/m 2 ) were included and performed demi-plié in control, functional turnout, and forced turnout conditions. Ultrasound imaging synchronized with a three-dimensional motion analysis system was used for measuring the vertical locations of the first metatarsal and medial cuneiform (MC) to evaluate the first TMT joint mobility. Plantar displacement of MC and the first TMT joint mobility in the forced turnout were the greatest among the 3 conditions. Multiple regression analysis indicated that the greater extent of the forcing angle might increase the displacement of MC and the first TMT joint mobility. Evaluating the sagittal mobility of the first TMT joint in the forced turnout can assist in understanding the association between inappropriate techniques including the forced turnout and HV development in ballet dancers. Since the excessive mobility of the first TMT joint is a factor in HV development, the acquirement of adequate active turnout may have the potential to prevent HV development in ballet dancers., (© 2024. The Author(s).)

Background: A previous study defined the normal first metatarsal pronation angle (MPA) as <16 degrees and normal α angle as <18 degrees. The primary purpose of this study was to assess the side-to-side variation in first metatarsal pronation between feet in normal individuals., Methods: MPA and α angles were measured on standardized coronal weightbearing computed tomography slices. Paired t tests were used to test significance of mean side-to-side differences in a population of 63 normal, asymptomatic individuals., Results: The mean side-to-side difference in first metatarsal pronation was 4.3 degrees (95% CI 3.3, 5.2 degrees) for MPA and 4.9 degrees (95% CI 3.8, 6.0 degrees) for α angle. The normative range for side-to-side difference was calculated as 12 degrees for MPA and 14 degrees for α angle, as defined by 2 SDs from the mean., Conclusion: In a cohort of normal patients, the mean difference in first metatarsal pronation between sides was approximately 4 to 5 degrees based on MPA and α angle. However, considerable variation in differences was observed. These findings may be considered when assessing first metatarsal pronation using population-based values as it may influence thresholds for identifying pathology in an individual.

This study investigated the feasibility of combined padded metatarsal cup on plantar pressures and stress distribution in the bone alignment of female foot with high heeled footwear during balanced standing. The aim of this study is to redistribute the plantar pressure away from the medial side of the forefoot. A combined padded metatarsal cup (CPMC) was developed from medium soft ethylene vinyl acetate (MSEVA) and very soft ethylene propylene diene monomer (VSEPDM) neoprene sponge. The participants of three categories were selected for the study. The peak plantar pressure and a radiographic assessment of foot musculoskeletal alignment were carried out. The results showed that the magnitude of load on medial forefoot area could be effectively reduced by inserting joint of soft materials on metatarsal region. Hence load on hallux could also be reduced satisfactorily which could resist the hallux valgus deformity. A comparison of conventional system and jointing materials separately with the developed prototype was made and found that the developed prototype of CPMC provides more relaxation of plantar pressure and musculoskeletal safety and confirms more comfort on hypothesis test. The concept of combined padded metatarsal cup should therefore be considered to help in designing musculoskeletal safety footwear.

During the Neogene, many North American ungulates evolved longer limbs. Presumably, this allowed them to move more efficiently or quickly in open habitats, which became more common during this interval. Evidence suggests that open habitats appeared even earlier in South America, but no study to date has investigated whether the ungulate-like mammals of South America (South American native ungulates or SANUs) evolved similar limb adaptations. We analyzed limb elongation in the two predominant SANU groups, notoungulates and litopterns, by compiling genus-level occurrences from the late Oligocene to the Pleistocene and calculating metatarsal/femur ratio (Mt:F). None of the groups or subgroups we analyzed show a pronounced increase in Mt:F across this interval, with the possible exception of proterotheriid litopterns. Proterotheriids are thought to have inhabited forested environments rather than open ones, which raises questions about the selective forces responsible for limb elongation in ungulates. Conversely, notoungulates, which are traditionally thought to have lived in open habitats, show no strong trend of increasing Mt:F across this interval. Our study suggests that the macroevolutionary trend of limb elongation in ungulate-like mammals is not universal and is highly influenced by the evolutionary affinities of the groups being analyzed., Competing Interests: The authors have declared that no competing interests exist.

Background: This study aimed to investigate the differences in plantar pressure during various athletic activities on natural grass and artificial turf., Methods: Twenty-one athletes were fitted with properly sized soccer shoes and corresponding F-Scan system insoles and performed walking, running, vertical jumping and cutting activities to the right and left sides on both natural and artificial turf., Results: There were no statistically significant differences between natural grass and artificial turf in peak pressure, maximum force and force-time integral during all the athletic activities (P˃0.05). On both turfs, the highest peak pressure and maximum force values occurred during running and cutting to the right, and the highest force-time integral value occurred during cutting to the right. There were no statistically significant differences between the two turfs in peak pressure in the various anatomical regions during any of the athletic activities (P˃0.05). The peak pressure was the highest on the first metatarsal and the hallux during all five activities. A clinically meaningful difference between the surfaces in peak pressure on the second to fifth metatarsals was found during walking, indicating more loading on artificial turf than on natural grass. There was more loading on artificial turf than on natural grass during cutting left and at hallux and third toe on natural grass during cutting right. However, these differences were not statistically significant (P˃0.05)., Conclusions: The results of this study suggest that it is important to limit or prevent athletes from undertaking certain activities that increase the risk of re-injury during rehabilitation.

We investigated the impact of visual impairment on balance control. We measured the center of pressure (COP) between the two feet and plantar surface pressures on each foot in 18 normal-sighted participants and compared their data with measures from 18 legally blind participants, either acquired or congenital. Pressures were measured in open- and closed-eye conditions using a baropodometric resistive plate. In the eyes-open condition, there were no differences between the sighted and legally blind groups in COP displacement. However, participants with visual loss had significantly increased pressures in two metatarsal regions (M1 and M2 zones) of the plantar surface in both viewing conditions (p < 0.05). The differences in pressure measures between the normally sighted and legally blind groups could be attributed mainly to the subgroup of subjects with acquired impairment. Our findings suggest that subjects with visual impairment present increased metatarsal pressures (i.e. forefoot), not yet associated to anterior displacement of COP or impaired balance control., Competing Interests: The authors have declared that no competing interests exist.

Aims: To establish normative values of vibration perception thresholds (VPTs), using multi-frequency vibrometry at finger pulps and at metatarsal heads of the foot in healthy adults. We also aimed to investigate factors that could potentially affect VPTs such as age, sex, height, weight, foot- or handedness and skin temperature., Methods: VPTs were examined in 924 healthy and randomly selected subjects in the southern Sweden (mean 46 years; 628 women and 296 men). Inclusion criterias were adult subjects (>18 years) in considerable health without diabetes mellitus or other nerve affecting disorders. VPTs were measured at the finger pulps of index and little finger, as well as the first and fifth metatarsal heads of the foot, through multi-frequency vibrometry using the VibroSense Meter® I device. Patient characteristics were recorded and skin temperature was measured before assessment of VPTs., Results: We present normative values of VPTs for a large population of both male and female subjects in various ages. VPTs detoriated as age increased (0.09-0.59 dB per year; p<0.001), i.e. progressing with normal aging. Increasing skin temperature affected VPTs in finger pulps, but not at metatarsal heads, with -0.2 to -1.6 dB, i.e. vibration perception improved with higher temperatures. Height was only found to affect the VPTs of metatarsal heads (250 Hz: 0.42 dB per cm). Sex, weight and handedness did not affect the VPTs., Conclusion: We investigated the normative values of VPTs and presented affecting factors as age, skin temperature and height. With these results, VPT testing through multi-frequency vibrometry is enabled to be used in a clinical practice as a diagnostic tool when investigating neuropathy and other neurological disorders., Competing Interests: The authors have declared that no competing interests exist.

Bone lengthening and bone transport are regeneration processes that commonly rely on distraction osteogenesis, a widely accepted surgical procedure to deal with numerous bony pathologies. Despite the extensive study in the literature of the influence of biomechanical factors, a lack of knowledge about their mechanobiological differences prevents a clinical particularization. Bone lengthening treatments were performed on sheep metatarsus by reproducing the surgical and biomechanical protocol of previous bone transport experiments. Several in vivo monitoring techniques were employed to build an exhaustive comparison: gait analysis, radiographic and CT assessment, force measures through the fixation, or mechanical characterization of the new tissue. A significant initial loss of the bearing capacity, quantified by the ground reaction forces and the limb contact time with the ground, is suffered by the bone lengthening specimens. The potential effects of this anomaly on the musculoskeletal force distribution and the evolution of the bone callus elastic modulus over time are also analyzed. Imaging techniques also seem to reveal lower bone volume in the bone lengthening callus than in the bone transport one, but an equivalent mineralization rate. The simultaneous quantification of biological and mechanical parameters provides valuable information for the daily clinical routine and numerical tools development.

Bone lengthening is a bone regeneration technique with multiple clinical applications. One of the most common complications of this treatment is the lack of adaptation of the surrounding soft tissue to their extension. A better understanding of the mechanobiology of the tissues involved in distraction osteogenesis would allow better control of the clinical cases. Bone lengthening treatments were performed in vivo in the metatarsus of Merino sheep, measuring the distraction forces by means of an instrumented fixator. The tissue relaxation after distraction was analyzed in this study. A viscoelastic model was also applied to distraction data to assess the mechanical behavior of the tissues during the distraction phase. Tissue relaxation is similar to other bone regeneration processes which do not imply surrounding soft tissue extension, e.g. bone transport. The effects of this tissue on distraction forces are limited to the first minutes of distraction and elongations above 4% of the original length with the protocol applied. Moreover, the surrounding soft tissue initially loses some of its viscoelasticity and subsequently suffers strain hardening from day 5 of distraction until the end of the distraction phase, day 15. Finally, anatomical changes were also evidenced in the elongated limb of our specimens.

Objectives: Hallux valgus (HV) is a progressive foot deformity in which the first metatarsophalangeal (MTP) joint is affected. The relationship between the dome height of the first metatarsal head and the HV deformity has not been studied previously. This study aimed to investigate a possible relation of the dome height of the first metatarsal head with articular alignment and the hallux valgus angle (HVA), which is frequently used to evaluate HV., Methods: A total of 129 feet of 68 patients were included in the study. Anteroposterior digital radiographic images of the foot taken in a weightbearing, standing position were used to assess the HVA, dome height, and shape of the first metatarsal head and the alignment of the MTP joint. The dome height of the first metatarsal head is the vertical distance from the base to the highest point of the articular surface doming. The alignment was categorized into three groups: aligned, deviated, and subluxated. Patients were assigned into three groups based on the HVA: Normal, Mild HV and Moderate HV., Results: A statistically significant, positive correlation was found between the HVA and the dome height of the first metatarsal head (r = 0.293, P = 0.001 and P < 0.05). The dome height was significantly lower in the patients with a normal HVA than those with a high HVA (P1 = 0.042, P2 = 0.039 and P < 0.05, respectively). The dome height of the first metatarsal head was found significantly higher in feet with subluxation, compared to feet aligned and deviated (P1 = 0.001; P2 = 0.0089 and P < 0.05, respectively)., Conclusions: Our study results suggest that HV deformity may be related to an increased dome height and the measurement of the dome height of the first metatarsal head might be used to evaluate an anatomic tendency toward HV development., (American Podiatric Medical Association.)

Background: Shortening and dorsiflexion of the first metatarsal are known potential side effects of metatarsal osteotomies for hallux valgus (HV) with the potential to cause transfer metatarsalgia. We compared the effect of the first tarsometatarsal joint arthrodesis (Lapidus procedure), proximal lateral closing wedge osteotomy (PLCWO), and intermetatarsal suture button fixation procedures on the length and dorsiflexion of the first ray., Methods: We retrospectively evaluated 105 feet in 99 patients with 30 weeks of follow-up. The average age was 54 years. Seventy-four feet had a Lapidus procedure, 12 had a PLCWO, and 19 had intermetatarsal suture button fixation. Digital radiographic measurements were made for the pre- and postoperative hallux valgus angle (HVA) and intermetatarsal angle (IMA), absolute and relative shortening of the first ray, and dorsiflexion., Results: Preoperative HVA and IMA did not differ between treatment groups ( P > .05 for each). Similar corrections of HVA (30.5-13.5 degrees) were achieved between all groups ( P > .05). The IMA was improved more in the Lapidus group (14.3-6.5 degrees) compared with the suture button fixation group (14.2-8.1 degrees) ( P = .045). There were significant differences in the change in absolute first cuneiform-metatarsal length (FCML) between the Lapidus (-1.6 mm), PLCWO (-2.3 mm), and intermetatarsal suture button fixation (+1.9 mm) procedure ( P = .004). There were also significant differences in relative first metatarsal shortening between the Lapidus (0.1 mm relative shortening), PLCWO (1.1 mm relative shortening), and intermetatarsal suture button fixation (1.3 mm lengthening) procedure ( P < .001). The average dorsiflexion differed between the Lapidus (1.8 degrees) and suture button fixation (0.4 degrees) groups ( P = .004)., Conclusion: Intermetatarsal suture button fixation relatively lengthened the first ray, the Lapidus procedure maintained length, and the PLCWO relatively and absolutely shortened it. Dorsiflexion may be higher with the Lapidus and osteotomy procedures., Level of Evidence: Level III, retrospective comparative series.

Introduction: High heeled shoes have long been worn in society and they are known to cause biomechanical imbalances to not only the foot, but the whole musculoskeletal system. This study aims to show the detailed changes that happen to the shape of the transverse arch of the foot in high heels, using two different inclination degrees., Methods: 68 women participated in this study. Two custom-made high heels were made with inclinations of 15 degrees and 30 degrees (cm). A weight-bearing ultrasound was used to assess the coronal view of the transverse arch in standing. ANOVA and Tuckey tests were used to compare the results between 0 degrees, 15 degrees and 30 degrees inclinations., Results: The transverse arch height was slightly increased as the heel height increased (0DI-15DI: p = 0.5852 / 15DI-30DI: p = 0.395 / 0DI-30DI: p = 0.0593). The transverse arch length (0DI-15DI: p = 0.0486 / 15DI-30DI: p = 0.0004 / 0DI-30DI: p = 0.1105) and the area under the metatarsal heads (0DI-15DI: p = 0.0422 / 15DI-30DI: p = 0.0180 / 0DI-30DI: p = 0.9463) significantly decreased as the heel height increased., Discussion: The main changes were viewed in the 30 degrees inclinations compared to 0 degrees inclination. When the toes are dorsiflexed in high heels, it stimulates the Windlass mechanism which in turn stiffens the plantar fascia and adducts the metatarsal heads, while the soft tissues shrink in response to loads., Conclusion: High heels affected the shape of the transverse arch even in short term standing, and these effects increased as the height of the heel increased., Competing Interests: The authors have declared that no competing interests exist.

Background: The aim of this study was to evaluate the effect of 12 weeks of use of orthopedic insoles equipped with a metatarsal retro-capital bar (MRCB) on plantar pressure under the feet and lower limb kinematic variables during running., Methods: Two groups of 10 runners used for 12 weeks while running orthopedic insoles without correction or equipped with a MRCB. All participants performed successively a standing posture (CoP displacement) test and a running test at 11 km.h-1 (lower limb kinematic variables) using with flat insoles and orthopedic neutral or MRCB insoles at the beginning (T0), after 4 (T4) and 12 weeks (T12) of use., Results: For the MRCB group, CoP moved backwards while forefoot plantar pressure was decreased during standing position at T4 and T12 compared to T0. During running, the plantar pressure under the 2nd, 3rd and 4th metatarsal heads was reduced with MRCB at T0, T4 and T12. The one under the 1st metatarsal head was decreased at T4 and T12, when MRCB or flat insoles were used. The maximal extension and the total amplitude of ankle were slightly increased at T4 and T12 with or without wearing MRCB insoles. Similar changes in knee joint kinematics were observed but only at T12. Any significant changes were found in runners that used orthopedic insoles without correction., Conclusions: Orthopedic insoles equipped with MRCB involve lower plantar pressure under the metatarsal heads, which may be of interest to treat forefoot injuries in runners.

Pododermatitis is prevalent in falcons and is characterized by inflammation and infection of the plantar aspect of the feet, particularly at the central metatarsal pad. Suboptimal perch design and increased weight loading on the plantar skin have been proposed as major risk factors for the development of pododermatitis. Prevention and treatment are challenging, but weight load reduction on the affected area of the foot is an accepted goal of initial treatment. To date, to our knowledge no studies have compared the performance of different bandage-perch surface combinations on weight redistribution away from the central metatarsal pad. An ex vivo factorial experiment was designed using the feet from a peregrine falcon cadaver to quantify weight load reduction on the central metatarsal pad with different combinations of perch surfaces (wood, neoprene, artificial turf) and bandages (none, interdigital, silicone shoe). Feet were attached to a digital force gauge mounted on a manual test stand for compression testing. Weight loading at the central metatarsal pad was measured using a small force sensor. Perch-surface combinations in randomized order were tested at 250 g, 500 g, and 1 kg with 9 replicates per foot. At 250 g, all combinations reduced measured metatarsal pad forces, but otherwise performed similarly. As compression forces increased, differences emerged with the shoe combinations performing better overall, followed by a group including the neoprene and artificial turf-interdigital bandage combinations, and a third group including the interdigital/wood and no bandage-artificial turf. All combinations performed better than control (no bandage on wood). This study may assist veterinarians in selecting appropriate perching surface/bandage combinations when treating falcons with pododermatitis.

Second metatarsal stress fractures are a problematic injury for runners and are formed when the rate of repair of bone is outpaced by the damage accumulated during loading. Measuring the peak stresses on the bone during running gives an indication of damage accumulation but direct measurement is invasive. Finite element modelling is a viable alternative method of accurately estimating bone stresses but tends to be too computationally expensive for use in applied research. This study presents a novel and simple finite element model which can estimate bone stresses on the second metatarsal during the stance phase of walking and running, accounting for joint reaction forces and soft tissue effects. The influence of the forces and kinematic inputs to the model and the presence of the soft tissues was quantified using a sensitivity analysis. The magnitudes of maximum stress from the model are similar to existing finite element models and bone staple strain gauge values collected during walking and running. The model was found to be most sensitive to the pitch angle of the metatarsal and the joint reaction forces and was less sensitive to the ground reaction forces under the metatarsal head, suggesting that direct measurement of external forces should not be assumed to represent internal stresses.

Backgrounds: There has long been a consensus that shortening of the first metatarsal during hallux valgus reconstruction could lead to postoperative transfer metatarsalgia. However, appropriate shortening is sometimes beneficial for correcting severe deformities or relieving stiff joints. This study is to investigate, from the biomechanical perspective, whether and how much shortening of the first metatarsal could be allowed., Methods: A finite element model of the human foot simulating the push-off phase of the gait was established. Progressive shortening of the first metatarsal from 2 to 8 mm at an increment of 2 mm were sequentially applied to the model, and the corresponding changes in forefoot loading pattern during push-off phase, especially the loading ratio at the central rays, was calculated. The effect of depressing the first metatarsal head was also investigated., Results: With increasing shortening level of the first metatarsal, the plantar pressure of the first ray decreased, while that of the lateral rays continued to rise. When the shortening reaches 6 mm, the load ratio of the central rays exceeds a critical threshold of 55%, which was considered risky; but it could still be manipulated to normal if the distal end of the first metatarsal displaced to the plantar side by 3 mm., Conclusions: During the first metatarsal osteotomy, a maximum of 6 mm shortening length is considered to be within the safe range. Whenever a higher level of shortening is necessary, pushing down the distal metatarsal segment could be a compensatory procedure to maintain normal plantar force distributions.

Dancers are highly trained athletes who are at significant risk of injury due to the repetitive nature of their movement patterns. Most ballet injuries result from overuse and occur in the lower limbs. Therefore, the behavior of the lower limbs during a basic ballet movement should be studied in order to identify and subsequently correct mechanical factors that may contribute to injuries. This study analyzed a cou-de-pied derrière with demi-plié to piqué arabesque gesture executed by 18 ballet dancers identified in two groups: experienced dancers (EDs) and beginner dancers (BDs). Kinematic, baropodometric, and electromyographic analyses enabled the observation of differences between these study groups with regard to joint angles, velocities, foot pressure behavior, and muscle activation during execution of the gesture. Experienced dancers reached greater hip and lumbar spine hyperextension and demonstrated less forward torso flexion, which enables better execution of the gesture compared to BDs. The highest foot pressure in both groups was found in the first metatarsal, with a tendency toward the great toe. In terms of muscular activation, BDs exhibited lower electrical activity than EDs. It is concluded that: 1. ankle and knee angles in demi-plié are not defined by dancers' expertise; 2. the faster the leg is raised during piqué-arabesque the better the gesture; 3. special attention to the metatarsal heads is required due to the high pressures found in this study; and 4. activation of different muscle groups depends on the complexity of the gesture and dancer's expertise.

Ballerinas use their ankle joints more extremely and sustain injuries on the ankle joint more frequently than non-dancers. Therefore, the ankle movement of dancers is important and should be studied to prevent injuries. Measuring ankle joint range of motion (ROM) using radiographs could demonstrate the contribution to motion of each joint. The aim of this study was to analyse and compare ankle joint movements and the ratio of each joint's contribution during movement between dancers and non-dancers, using radiographic images. Dancers have lower dorsiflexion (26.7 ± 6.2°), higher plantarflexion (74.3 ± 7.1°) and higher total (101.1 ± 10.8°) ROMs than non-dancers (33.9 ± 7.0°, 57.2 ± 6.8° and 91.1 ± 9.3°, respectively) ( p  < 0.05). Although the ROMs were different between the two groups, the ratios of each joint movement were similar between these two groups, in all movements. Regarding total movement, the movement ratio of the talocrural joint was almost 70% and other joints accounted for almost 30% of the movement role in both dancers and non-dancers. Therefore, the differences in ROM between dancers and non-dancers were not a result of a specific joint movement but of all the relevant joints' collaborative movement.

Background: The aim of this study was to observe the pressure changes in the felt padding used to off-load pressure from the first metatarsal head, the effects obtained by different designs, and the loss of effectiveness over time., Method: With a study population of 17 persons, two types of 5-mm semicompressed felt padding were tested: one was C-shaped, with an aperture cutout at the first metatarsophalangeal joint, and the other was U-shaped. Pressures on the sole of the foot were evaluated with a platform pressure measurement system at three time points: before fitting the felt padding, immediately afterward, and 3 days later., Results: In terms of decreased mean pressure on the first metatarsal, significant differences were obtained in all of the participants ( P < .001). For plantar pressures on the central metatarsals, the differences between all states and time points were significant for the C-shaped padding in both feet ( P < .001), but with the U-shaped padding the only significant differences were between no padding and padding and at day 3 ( P = .01 and P = .02)., Conclusions: In healthy individuals, the U-shaped design, with a padding thickness of 5 mm, achieved a more effective and longer-lasting reduction in plantar pressure than the C-shaped design.

The purpose of this study was to determine the optimal inner-shoe volume for children tennis players. Sixteen participants, aged from 8 to 12 years old assessed comfort of 6 shoes, which were a combination of 3 lasts (thin, medium and wide) and 2 upper constructions (flexible and stiff), while a sock equipped with textile sensors was measuring the pressure applied on their foot. The thin last was based on the proportion of an adult last. The widest shoes produced the lowest pressure on the 1st and 5th metatarsal heads, the medial midfoot and the medial and lateral heel (p < 0.05), whilst they were perceived the most comfortable for the 3rd and 5th metatarsal heads, the 5th metatarsal base and the medial and lateral heel (p < 0.05). These outcomes indicated that footwear manufacturers should design wider shoes for children than for adults., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

To evaluate the rotational change in the first metatarsal bone (1MT) of the foot during natural standing using an upright computed tomography (CT) scanner with 320-detector rows. A total of 52 feet of 28 asymptomatic subjects (aged 23-39 years) were evaluated in the natural standing position with or without weight-bearing. A foot pressure plate was used to determine the non-weight-bearing (NWB) or single leg full-weight-bearing (s-FWB) conditions. CT examinations were performed using a noise index of 15 for a slice thickness of 5 mm, rotation speed of 0.5 sec, and slice thickness of 0.5 mm. The rotation of the 1MT was measured on the coronal CT image, which cut the sesamoids' bellies in the frontal slide of the first metatarsal and sesamoids perpendicular to the longitudinal bisection of the third metatarsal, and compared between the weight-bearing conditions. Intra- and inter-observer reliabilities of the rotation angle were also evaluated. The intra- and inter-observer correlation coefficients were 0.961 and 0.934, respectively. The 1MT pronation angle was significantly greater in the s-FWB condition than in the NWB condition (15.2° ± 5.4° vs. 12.5° ± 5.3°, P < 0.01). No sex difference was found in the magnitude of the 1MT pronation angle as a result of weight-bearing. This study first demonstrated that pronation of 1MT occurs due to natural full-weight-bearing in asymptomatic feet. The 1MT's rotational movement under weight-bearing conditions may relate to the onset and pathogenesis of the hallux valgus. Clin. Anat. 32:715-721, 2019. © 2019 Wiley Periodicals, Inc., (© 2019 Wiley Periodicals, Inc.)

The medial-longitudinal arch (MLA) is perhaps the most important feature characterizing foot morphology. While current skin-markers based models of the MLA angle used in stereophotogrammetry allow to estimate foot arch shape and deformation, these do not always appear consistent with foot anatomy and with standard clinical definitions. The aim of this study was to propose novel skin-markers based measures of MLA angle and investigate their reliability during common motor tasks. Markers on the calcaneus, navicular tuberosity, first metatarsal head and base, and on the two malleoli were exploited to test eight definitions of MLA angle consistent with foot anatomy, both as angles between two 3-dimensional vectors and as corresponding projections on the sagittal plane of the foot. The inter-trial, inter-session and inter-examiner reliability of each definition was assessed in multiple walking and running trials of two volunteers, tested by four examiners in three sessions. Inter-trial variability in walking was in the range 0.7-1.2 deg, the inter-session 2.8-7.5 deg, and the inter-examiner in the range 3.7-9.3 deg across all MLA definitions. The Rizzoli Foot Model definition showed the lowest inter-session and inter-examiner variability. MLA measures presented similar variability in walking and running. This study provides preliminary information on the reliability of MLA measurements based on skin-markers. According to the present study, angles between 3-dimensional vectors and minimal marker sets should be preferred over sagittal-plane projections. Further studies should be sought to investigate which definition is more accurate with respect to the real MLA deformation in different loading conditions., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Previous research has identified separate sagittal plane instantaneous centers of rotation for the metatarso-phalangeal and metatarso-sesamoid joints, but surprisingly, it does not appear that any have integrated the distinctive morphological characteristics of all three joints and their respective axes into a model that collectively unifies their functional motions. Since all joint motion is defined by its centers of rotation, establishing this in a complicated multi-dimensional structure such as the metatarso-phalangeal-sesamoid joint complex is fundamental to understanding its functionality and subsequent structural failures such as hallux abducto valgus and hallux rigidus., Methods: Based on a hypothesis that it is possible to develop an instantaneous center of rotation common to all four osseous structures, specific morphometrics were selected from a sequential series of 0.5-mm sagittal plane C-T sections in one representative cadaver specimen randomly selected from a cohort of nine, seven which were obtained from the Body Donation Program, Department of Anatomy, University of California, San Diego School of Medicine, and two which were in the possession of one author (MD). All mature skeletal specimens appeared grossly normal, shared similar morphological features, and displayed no evidence of prior trauma, deformity, or surgery. Specific C-T sections isolated the sagittal plane characteristics of the inter-sesamoidal ridge and each sesamoid groove, and criteria for establishing theoretical sesamoid contact points were established. From these data, a geometric model was developed which, to be accurate, had to closely mimic all physical and spatial characteristics specific to each bone, account for individual variations and pathological states, and be consistent with previously established metatarso-phalangeal joint functional motion., Results: Sequential sagittal plane C-T sections dissected the metatarsal head from medial to lateral and, at approximately midway through the metatarsal head, the circular nature of the inter-sesamoidal ridge (crista) was isolated; other C-T sections defined, respectively, the elliptical characteristics of the tibial (medial) and fibular (lateral) sesamoid grooves in each specimen. A general plane model representing the most basic form of the joint was developed, and its center of rotation was established with a series of tangential and normal lines. Simplified tibial sesamoid and fibular plane models were developed next which, when combined, permitted the development of a spherical model with three separate contact points. Based on the morphometrics of each sesamoid groove and a more distally positioned tibial sesamoid, the model was modified to accurately define the center of rotation and one distinctive sagittal plane geometric and functional characteristic of each groove., Conclusion: Consistent with our hypothesis, this theoretical geometric model illustrates how it is possible to define an instantaneous center of rotation common to all three joints while simultaneously accounting for morphometric and spatial variability. This should provide additional insight into metatarso-phalangeal-sesamoid joint complex functionality and the physical characteristics that contribute to its failure.

Introduction: The translation of the navicular bone is thought to be a representative surrogate measure to assess foot pronation and hence foot function; however, it is not known how it is related to multi-segment foot kinematics., Methods: Cranio-caudal (NCC) and medio-lateral (NML) navicular translation and multi-segment foot kinematics from the Oxford Foot Model (OFM) were simultaneously assessed during the stance phase of walking in 20 healthy adults. Relationships to forefoot to hindfoot (FFtoHF), hindfoot to tibia (HFtoTBA) and global hindfoot (HFL) motion were explored by cross-correlations at zero phase shift., Results: FFtoHF sagittal, transversal and frontal plane angles showed median cross correlations of -0.95, 0.82 and 0.53 with NCC and of 0.78, -0.81 and -0.90 with NML. HFtoTBA transversal and frontal plane angles had correlations of 0.15 and 0.74 with NCC and of -0.38 and -0.83 with NML. The HFL frontal plane angle showed correlations of 0.41 and -0.44 with NCC and NML, respectively., Discussion: The strongest relationships were found between FFtoHF sagittal plane angles and NCC and between FFtoHF frontal plane angles and NML. However, cranio-caudal and medio-lateral navicular translation seem to be reasonable surrogates for the triplanar motion between the fore- and hindfoot. The medial longitudinal arch dropped and bulged medially, while the forefoot dorsiflexed, abducted and everted with respect to the hindfoot and vice-versa. The lower cross-correlation coefficients between the rear foot parameters and NCC/NML indicated no distinct relationships between rearfoot frontal plane and midfoot kinematics. The validity of rearfoot parameters, like Achilles tendon or Calcaneal angle, to assess midfoot function must be therefore questioned. The study could also not confirm a systematic relationship between midfoot kinematics and the internal/external rotation between the hindfoot and the tibia. The measurement of navicular translation is suggested as an alternative to more complex multi-segment foot models to assess foot function., Competing Interests: The authors have declared that no competing interests exist.

Background: Deformity of the first ray in hallux valgus patient has been deemed to mainly contribute to instability of the metatarsophalangeal joint. However, it is not clear whether the fixation of the distal osteotomy fragment and transposition of the sesamoid represent the best method for hallux valgus treatment. The aim of this study was to examine how postoperative hallux valgus osteotomy affects the stability of the first ray., Methods: To accurately investigate the biomechanical behavior of the first ray in pre-/postoperative hallux valgus patients, we described the relative displacement and stress distribution of the first metatarsal bone and sesamoid by imageology, test measurement and foot finite element model., Findings: Compared with the preoperative hallux valgus, the plantar pressure decreased by 47.8% and was redistributed on second metatarsal region. The peak stress and relative displacement of the distal osteotomy fragment increased by +55.7% and -59.9%, respectively. The movement of this component shifted toward the positive sagittal axis direction. In addition, the relative displacement of sesamoid decreased by 87.4% (0.18 mm) in vertical axis direction and the stress was also redistributed on medial and lateral region. Moreover, the strain of the medial main ligament was more favorable to reconstruct function of the first ray., Interpretation: The findings showed that the osteotomy method was helpful for stability of the first ray. This would provide the stability suggestions for postoperative hallux valgus fixation and guide further rehabilitation., (Copyright © 2018. Published by Elsevier Ltd.)

Background: Plano-valgus is a common alteration of the paediatric foot, characterized by valgus hindfoot, foot pronation and drop of the medial longitudinal arch. Despite their importance in the diagnosis and classification of plano-valgus foot condition, little information is available on functional alterations of the major joints spanning the medial longitudinal arch - i.e. midtarsal and tarso-metatarsal. Aim of the study was to provide objective description of the alterations in plano-valgus midfoot joints with respect to those in an age-matched normally-developed feet population., Methods: Twenty adolescents (13.3 ± 0.8 years) with bilateral plano-valgus feet underwent clinical examination and were gait-analysed via a validated 4-segment foot model. This allowed to measure static foot posture, kinematics of the main foot joints, and medial longitudinal arch deformation during walking at comfortable speed. Range of motion and temporal profiles of joint rotations were compared to those from a control population of age-matched adolescents with normally-developed feet., Results: The plano-valgus midtarsal joint was more dorsiflexed, everted and abducted than that in the control group, and showed reduced sagittal-plane RoM (plano-valgus = 15.9 degrees; control = 22.2 degrees; P  <  0.01). The tarso-metarsal joint was more plantarflexed and adducted, and showed larger frontal-plane RoM. The MLA showed larger RoM and was lower throughout the stance phase of the gait cycle., Conclusion: Significant postural and kinematic alterations are present at the midtarsal and tarso-metarsal joints of adolescents with plano-valgus feet. Objective identification and quantification of plano-valgus foot alterations, via non-invasive gait-analysis, is relevant to improving the diagnosis of this condition and to evaluating the effect of conservative treatments and of surgical corrections by different techniques., Competing Interests: Acknowledgement of the Hospital’s IRB was granted (protocol n° 7/17) and parents’ informed consent was obtained for all children recruited in the study.Parents’ consent to publish was granted.The authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

The primate foot functions as a grasping organ. As such, its bones, soft tissues, and joints evolved to maximize power and stability in a variety of grasping configurations. Humans are the obvious exception to this primate pattern, with feet that evolved to support the unique biomechanical demands of bipedal locomotion. Of key functional importance to bipedalism is the morphology of the joints at the forefoot, known as the metatarsophalangeal joints (MTPJs), but a comprehensive analysis of hominin MTPJ morphology is currently lacking. Here we present the results of a multivariate shape and Bayesian phylogenetic comparative analyses of metatarsals (MTs) from a broad selection of anthropoid primates (including fossil apes and stem catarrhines) and most of the early hominin pedal fossil record, including the oldest hominin for which good pedal remains exist, Ardipithecus ramidus Results corroborate the importance of specific bony morphologies such as dorsal MT head expansion and "doming" to the evolution of terrestrial bipedalism in hominins. Further, our evolutionary models reveal that the MT1 of Ar. ramidus shifts away from the reconstructed optimum of our last common ancestor with apes, but not necessarily in the direction of modern humans. However, the lateral rays of Ar. ramidus are transformed in a more human-like direction, suggesting that they were the digits first recruited by hominins into the primary role of terrestrial propulsion. This pattern of evolutionary change is seen consistently throughout the evolution of the foot, highlighting the mosaic nature of pedal evolution and the emergence of a derived, modern hallux relatively late in human evolution., Competing Interests: The authors declare no conflict of interest.

When measured as a ratio of mean midshaft diameter to bone length, the OH 8 fossil hominin foot exhibits a metatarsal (Mt) robusticity pattern of 1 > 5 > 3 > 4 > 2, which differs from the widely perceived "common" modern human pattern (1 > 5 > 4 > 3 > 2); African apes generally exhibit a third pattern (1 > 2 > 3 > 4 > 5). Largely because of the relative ranking of Mt2 and Mt5, OH 8 metatarsals structurally resemble the pattern exhibited by bipedal humans more than the pattern of quadrupedal and climbing African apes. Considering only these three phenotypes, however, discounts the potentially important functional implications of variation in modern human (and African ape) metatarsal robusticity patterns, suggesting that they are not useful for interpreting the specific biomechanics of a bipedal gait in fossils (i.e., whether it was modern human-like or not). Using computed tomography scans to quantify metatarsal midshaft cross-sectional geometry in a large sample of Homo (n=130), Gorilla (n=44) and Pan (n=80), we documented greater variation in metatarsal robusticity patterns than previously recognized in all three groups. While apes consistently show a 1 > 2 > 3 > 4 > 5 pattern in our larger sample, there does not appear to be a similarly precise single "common" human pattern. Rather, human metatarsals converge towards a 1 > 4/5 > 2/3 pattern, where metatarsals 4 and 5, and metatarsals 2 and 3, often "flip" positions relative to each other depending on the variable examined. After reassessing what a "common" human pattern could be based on a larger sample, the previously described OH 8 pattern of 1 > 5 > 3 > 4 > 2 is only observed in some humans (<6%) and almost never in apes (<0.5%). Although this suggests an overall greater similarity to (some) humans than to any ape in loading of the foot, the relatively rare frequency of these humans in our sample underscores potential differences in loading experienced by the medial and lateral columns of the OH 8 foot compared to modern humans., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: The metatarsal parabola or formula is an important principle in assessing normal foot structure and pathology. To understand what effect the positions of the distal ends of the metatarsals have on foot function, the relative length of each metatarsal must be considered. The purpose of this study was to investigate what the normal metatarsal formula is and compare these findings with previous research., Methods: Measurements of metatarsal lengths were taken from 20 feet of five male and five female cadavers. The mean lengths were used to identify each donor's metatarsal formula., Results: On average, the most common formula presented was in the order of metatarsals II>III>IV>V>I., Conclusions: These findings differ from historic measurements and raise questions regarding which metatarsal formula is considered normal. Further investigation is needed to standardize a more reliable method of measuring metatarsal lengths for evaluating foot biomechanics and planning forefoot surgeries.

Background: The validity of predicting foot pronation occurring mainly at the midfoot by surrogate measures from the rearfoot, like eversion excursion, is limited. The dynamic navicular mobility in terms of vertical navicular drop ( dNDrop ) and medial navicular drift ( dNDrift ) may be regarded as meaningful clinical indicators to represent overall foot function. This study aimed to develop a minimal approach to measure the two parameters and to examine their intra- and interday reliability during walking., Methods: The minimal markerset uses markers at the lateral and medial caput of the 1 st and 5 th metatarsals, respectively, at the dorsal calcaneus and at the tuberosity of the navicular bone. Dynamic navicular drop and drift were assessed with three-dimensional motion capture in 21 healthy individuals using a single-examiner test-retest study design., Results: Intra- and interday repeatability were 1.1 mm ( ICC 21 0.97) and 2.3 mm ( ICC 21 0.87) for dynamic navicular drop and 1.5 mm ( ICC 21 0.96) and 5.3 mm ( ICC 21 0.46) for dynamic navicular drift. The contribution of instrumental errors was estimated to 0.25 mm for dynamic navicular drop and 0.86 mm for dynamic navicular drift., Conclusions: Interday reliability was generally worse than intraday reliability primary due to day-to-day variations in movement patterns and the contribution of instrumental errors was below 23% for dynamic navicular drop but reached 57% for dynamic navicular drift. The minimal markerset allows to simply transfer the known concepts of navicular drop and drift from quasi-static clinical test conditions to functional tasks, which is recommended to more closely relate assessments to the functional behavior of the foot., Competing Interests: The study was approved by the ethics committee of the canton of Bern (KEK number Z007/12) and all participants signed informed consent.All participants were informed that the findings of the work may be published based on their data in fully anonymized form.The funding source had no involvement in study design, data collection, analysis and interpretation of data, in writing the manuscript and in the decision to submit the manuscript for publication. All authors state no conflict of interest.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Background: This study aimed to investigate the radiographic measurements associated with the progression of hallux valgus during at least 2 years of follow-up., Methods: Seventy adult patients with hallux valgus who were followed for at least 2 years and underwent weightbearing foot radiography were included. Radiographic measurements included the hallux valgus angle (HVA), hallux interphalangeal angle, intermetatarsal angle (IMA), metatarsus adductus angle, distal metatarsal articular angle (DMAA), tibial sesamoid position, anteroposterior (AP) talo-first metatarsal angle, and lateral talo-first metatarsal angle. Patients were divided into progressive and nonprogressive groups. Binary logistic regression analysis was performed to identify factors that significantly affected the progression of hallux valgus deformity. The correlation between change in HVA and changes in other radiographic indices during follow-up was analyzed., Results: The DMAA ( P = .027) and AP talo-first metatarsal angle ( P = .034) at initial presentation were found to be significant factors affecting the progression of hallux valgus deformity. Change in the HVA during follow-up was significantly correlated with changes in the IMA ( r = 0.423; P = .001) and DMAA ( r = 0.541; P < .001)., Conclusion: The change in the HVA was found to be significantly correlated with changes in the IMA and DMAA. A future study is required to elucidate whether this correlation can be explained by the progressive instability of the first tarsometatarsal joint. We believe special attention needs to be paid to patients with pes planus and increased DMAA., Level of Evidence: Level III, comparative study.

Due to the limitations of experimental approaches, comparison of the internal deformation and stresses of the human man foot between forefoot and rearfoot landing is not fully established. The objective of this work is to develop an effective FE modelling approach to comparatively study the stresses and energy in the foot during forefoot strike (FS) and rearfoot strike (RS). The stress level and rate of stress increase in the Metatarsals are established and the injury risk between these two landing styles is evaluated and discussed. A detailed subject specific FE foot model is developed and validated. A hexahedral dominated meshing scheme was applied on the surface of the foot bones and skin. An explicit solver (Abaqus/Explicit) was used to stimulate the transient landing process. The deformation and internal energy of the foot and stresses in the metatarsals are comparatively investigated. The results for forefoot strike tests showed an overall higher average stress level in the metatarsals during the entire landing cycle than that for rearfoot strike. The increase rate of the metatarsal stress from the 0.5 body weight (BW) to 2 BW load point is 30.76% for forefoot strike and 21.39% for rearfoot strike. The maximum rate of stress increase among the five metatarsals is observed on the 1st metatarsal in both landing modes. The results indicate that high stress level during forefoot landing phase may increase potential of metatarsal injuries., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

It has been demonstrated that the torsional patterns of the metatarsal heads are associated with the presence or absence of the medial longitudinal arch in hominoid feet. The relatively untwisted second metatarsal is unique in humans, but that of the African apes is much more inverted, suggesting that the torsion of the second metatarsal might represent the overall shape and flatness of the foot. Some clinical studies have recently argued that the onset of foot pathologies such as hallux valgus might be related to the torsional pattern of the metatarsals. However, to date, no studies have systematically investigated the morphological variations of the torsional patterns of human metatarsals. In this study, therefore, the aim was to clarify the age- and sex-associated variations in the torsional patterns of human metatarsals using three-dimensional computed tomography. The torsion angles of the five metatarsals were calculated by defining the dorsopalmar vector of the metatarsal base and the vector corresponding to the rotational axis of the metatarsal head. The present result demonstrated that the second metatarsals of females were significantly more inverted with increasing age. Flat foot is known to be most common in elderly women. Whether there is a cause-effect relationship between second metatarsal torsion and flattening of the medial longitudinal arch has yet to be answered, but this study suggested that torsion of the second metatarsal might possibly be used as an indicator for the early diagnosis of flat foot and associated foot pathologies. Clin. Anat. 30:1058-1063, 2017. © 2017 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)

Background: It has been reported that hallux valgus (HV) is associated with axial rotation of the first metatarsal (1MT). However, the association between HV and torsion of the 1MT head with respect to the base has not been previously investigated. The present study examined whether there was a significant difference in 1MT torsion between HV and control groups., Methods: Three-dimensional (3D) computed tomography (CT) scans of 39 ft were obtained, and 3D surface models of the 1MT were generated to quantify the torsion of the head with respect to the base. The HV group consisted of 27 ft from 27 women (69.5 ± 7.5 years old). Only the feet of HV patients with an HV angle >20° on weight-bearing radiography were selected for analysis. The control group consisted of 12 ft from 12 women (67.7 ± 7.2 years old). In a virtual 3D space, two unit vectors, which describe the orientation of the 1MT head and base, were calculated. The angle formed by these two unit vectors representing 1MT torsion was compared between the control and hallux valgus groups., Results: The mean (± standard deviation) of the torsional angle of the 1MT was 17.6 (± 7.7)° and 4.7 (± 4.0)° in the HV and control groups, respectively, and the difference was significant ( p  < 0.01)., Conclusions: This is the first study, to the best of our knowledge, to investigate 1MT torsion in HV patients using CT-based 3D analysis. The 1MT showed significant eversion in hallux valgus patients compared to control group patients.

Metatarsal stress fracture is a common injury observed in athletes and military personnel. Mechanical fatigue is believed to play an important role in the etiology of stress fracture, which is highly dependent on the resulting bone strain from the applied load. The purpose of this study was to validate a subject-specific finite element (FE) modeling routine for bone strain prediction in the human metatarsal. Strain gauge measurements were performed on 33 metatarsals from seven human cadaveric feet subject to cantilever bending, and subject-specific FE models were generated from computed tomography images. Material properties for the FE models were assigned using a published density-modulus relationship as well as density-modulus relationships developed from optimization techniques. The optimized relationships were developed with a 'training set' of metatarsals (n=17) and cross-validated with a 'test set' (n=16). The published and optimized density elasticity equations provided FE-predicted strains that were highly correlated with experimental measurements for both the training (r 2 ≥0.95) and test (r 2 ≥0.94) sets; however, the optimized equations reduced the maximum error by 10% to 20% relative to the published equation, and resulted in an X=Y type of relationship between experimental measurements and FE predictions. Using a separate optimized density-modulus equation for trabecular and cortical bone did not improve strain predictions when compared to a single equation that spanned the entire bone density range. We believe that the FE models with optimized material property assignment have a level of accuracy necessary to investigate potential interventions to minimize metatarsal strain in an effort to prevent the occurrence of stress fracture., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Arthroplasty of the first metatarsophalangeal joint is an alternative treatment option for end-stage hallux rigidus to the current gold standard of arthrodesis. The aim of this study was to investigate the mid-term functional outcome of an anatomically shaped prosthesis for the first metatarsophalangeal joint using pedobarography., Methods: Ten patients (12 affected feet; age at surgery: 62.1 (SD: 7.2) years) were investigated preoperatively and 52 (SD: 3) months postoperatively using pedobarography (EMED, novel GmbH, Munich, Germany). Two patients were excluded at follow-up because their prosthesis was converted to an arthrodesis. Peak force and plantar pressure under the five metatarsal heads and the hallux were analyzed and correlated with the clinical outcome (pain, American Orthopaedic Foot and Ankle Society forefoot score and radiographic maximum first metatarsophalangeal dorsiflexion). Differences between pre- and postoperative data were analyzed using paired t-tests (alpha=0.05)., Findings: Postoperatively, forefoot peak forces under the fourth (+40.9%; P=0.018) and fifth metatarsal (+54.9%; P=0.037) and plantar pressures under the fifth metatarsal (+38.7%; P=0.027) increased significantly, while peak plantar pressures and forces under the hindfoot, medial forefoot and hallux did not change. While maximum passive dorsiflexion was not significantly greater at the 4-year follow-up compared to preoperatively, overall greater passive dorsiflexion was associated with higher first metatarsal peak pressure., Interpretation: Despite of patients reporting less pain, the functional results indicate an altered and potentially non-physiological postoperative gait pattern with a lateralization of the load during walking, especially in patients with limited passive dorsiflexion., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Ankle inversion injuries are one of the most common and burdensome injuries in athletic populations. Research that prospectively identifies characteristics associated with this injury is lacking. This prospective study compared baseline anthropometric and biomechanical gait characteristics of military recruits who sustained an ankle inversion injury during training, with those who remained injury-free., Methods: Bilateral plantar pressure and three-dimensional lower limb kinematics were recorded in 1065 male, injury-free military recruits, during barefoot running. Injuries that occurred during the 32-week recruit training programme were subsequently recorded. Data were compared between recruits who sustained an ankle inversion injury during training (n=27) and a sample (n=120) of those who completed training injury-free. A logistic regression analysis was used to identify risk factors for this injury., Findings: A narrower bimalleolar width and an earlier peak pressure under the fifth metatarsal were predictors of ankle inversion injury. Those who sustained an ankle inversion injury also had a lower body mass, body mass index, and a smaller calf girth than those who completed training injury-free., Interpretation: Anthropometric and dynamic gait characteristics have been identified that may predispose recruits to an ankle inversion injury during Royal Marine recruit training, allowing identification of recruits at higher risk at the start of training., (Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.)

Background: Foot orthoses are frequently used in sports for the treatment of overuse complaints with sufficient evidence available for certain foot-related overuse pathologies like plantar fasciitis, rheumatoid arthritis and foot pain (e.g., metatarsalgia). One important aim is to reduce plantar pressure under prominent areas like metatarsal heads. For the forefoot region, mainly two common strategies exist: metatarsal pad (MP) and forefoot cushioning (FC). The aim of this study was to evaluate which of these orthosis concepts is superior in reducing plantar pressure in the forefoot during running., Methods: Twenty-three (13 female, 10 male) asymptomatic runners participated in this cross-sectional experimental trial. Participants ran in a randomised order under the two experimental (MP, FC) conditions and a control (C) condition on a treadmill (2.78 ms -1 ) for 2 min, respectively. Plantar pressure was measured with the in-shoe plantar pressure measurement device pedar-x®-System and mean peak pressure averaged from ten steps in the forefoot (primary outcome) and total foot was analysed. Insole comfort was measured with the Insole Comfort Index (ICI, sum score 0-100) after each running trial. The primary outcome was tested using the Friedman test (α = 0.05). Secondary outcomes were analysed descriptively (mean ± SD, lower & upper 95%-CI, median and interquartile-range (IQR))., Results: Peak pressure [kPa] in the forefoot was significantly lower wearing FC (281 ± 80, 95%-CI: 246-315) compared to both C (313 ± 69, 95%-CI: 283-343; p  = .003) and MP (315 ± 80, 95%-CI: 280-350; p  = .001). No significant difference was found between C and MP ( p  = .858). Peak pressures under the total foot were: C: 364 ± 82, 95%-CI: 328-399; MP: 357 ± 80, 95%-CI: 326-387; FC: 333 ± 81 95%-CI: 298-368. Median ICI sum scores were: C 50, MP 49, FC 64., Conclusions: In contrast to the metatarsal pad orthosis, the forefoot cushioning orthosis achieved a significant reduction of peak pressure in the forefoot of recreational runners. Consequently, the use of a prefabricated forefoot cushioning orthosis should be favoured over a prefabricated orthosis with an incorporated metatarsal pad in recreational runners with normal height arches.

A major purpose of investigating the plantar pressure in patients with pain or those at risk for skin injury is to reduce the pressure below metatarsal heads, specially first and second metatarsal heads. The aim of this article is to evaluate the effects of the socks structures on the changes in plantar dynamic pressure. In this study, seven socks types with different structures for the sole area were produced. The Gaitview ® AFA-50 system, a force plate, was used to measure the plantar dynamic pressure of 10 participants. The barefoot plantar dynamic pressure distribution was compared with the plantar dynamic pressure distribution with socks by two independent samples test on various zones of the foot and on different genders using SPSS software. Mann-Whitney tests were used to determine specific significant differences. The obtained results showed that the main trend was to redistribute the plantar dynamic pressure from the higher plantar pressure zones (toe and first through forth metatarsal bone regions) were decreased and as a result the plantar pressure toward the relatively lower pressure zones (fifth metatarsal bone and midfoot regions). In comparison with the barefoot condition, the cross miss structure reduced the mean pressure in the critical region of the foot (first metatarsal) for male and female subjects ( p < 0.05) and also the mock rib structure reduced the mean pressure for female subjects ( p < 0.05). In general, the results suggested wearing the socks because the socks make the plantar pressure redistributed from high to low plantar pressure zones. The results of this research indicated that wearing socks with cross miss and mock rib structures will reduce the mean plantar pressure values in forefoot area in comparison with the barefoot condition.

Foot abnormality has become a public health concern. Early detection of pathological soft tissue is therefore an important preventive measure, especially in older people who generally have a higher risk of foot pathology. However, the interpretation of plantar tissue stiffness data - whether to normalize the data or to separate the data on the basis of sex- remains questionable. The objective of this study was to assess the influence of sex and physical attributes such as body mass (BM) and body mass index (BMI) on plantar soft-tissue stiffness, and to evaluate whether it is necessary to isolate the differences in sex, BM and BMI in the data analysis. One hundred healthy subjects in their 60s were recruited for the experiment. Localized force response was obtained underneath the second metatarsal head (MTH) pad at three different dorsiflexion angles of 0°, 20°, 40° and the hallux and heel at 0°. No significant relationship was found between the independent variables and plantar stiffness. From the experimental results, it can be deduced that BM and BMI are weakly associated with plantar tissue stiffness, and that there is no significant difference in stiffness between male and female participants. No difference was found between left and right foot measurements. This suggests that normalizing of plantar tissue stiffness by BM and BMI is not necessary in healthy people in their 60s. The data can be pooled and treated equally regardless of sex., (Copyright © 2016. Published by Elsevier Ltd.)

Background: Electromagnetic bone growth stimulators have been found to biologically enhance the bone healing environment, with upregulation of numerous growth factors. The purpose of the study was to quantify the effect, in vivo, of pulsed electromagnetic fields (PEMFs) on growth factor expression and healing time in fifth metatarsal nonunions., Methods: This was a prospective, randomized, double-blind trial of patients, cared for by 2 fellowship-trained orthopedic foot and ankle surgeons. Inclusion criteria consisted of patients between 18 and 75 years old who had been diagnosed with a fifth metatarsal delayed or nonunion, with no progressive signs of healing for a minimum of 3 months. Eight patients met inclusion criteria and were randomized to receive either an active stimulation or placebo PEMF device. Each patient then underwent an open biopsy of the fracture site and was fitted with the appropriate PEMF device. The biopsy was analyzed for messenger-ribonucleic acid (mRNA) levels using quantitative competitive reverse transcription polymerase chain reaction (QT-RT-PCR). Three weeks later, the patient underwent repeat biopsy and open reduction and internal fixation of the nonunion site. The patients were followed at 2- to 4-week intervals with serial radiographs and were graded by the number of cortices of healing., Results: All fractures healed, with an average time to complete radiographic union of 14.7 weeks and 8.9 weeks for the inactive and active PEMF groups, respectively. A significant increase in placental growth factor (PIGF) level was found after active PEMF treatment (P = .043). Other factors trended higher following active PEMF including brain-derived neurotrophic factor (BDNF), bone morphogenetic protein (BMP) -7, and BMP-5., Conclusion: The adjunctive use of PEMF for fifth metatarsal fracture nonunions produced a significant increase in local placental growth factor. PEMF also produced trends toward higher levels of multiple other factors and faster average time to radiographic union compared to unstimulated controls., Level of Evidence: Level I, prospective randomized trial., (© The Author(s) 2016.)

Predicting location of fracture in human bones has been a keen area of research for the past few decades. A variety of tests for hardness, deformation and strain field measurement have been conducted in the past; but considered insufficient due to various limitations. Researchers therefore have proposed further studies due to inaccuracies in measurement methods, testing machines and experimental errors. Advancement and availability of hardware, measuring instrumentation and testing machines can now provide remedies to these limitations. Human foot is a critical part of body exposed to various forces throughout its life. A number of products are developed for using over it for protection and care. Which many times do not provide sufficient protection and may itself become a source of stress due to non-consideration of the delicacy of bones in the feet. A continuous strain or overloading on feet may occur resulting to discomfort and even fracture. Not knowing how the hardness is spread all over the Meta tarsals and phalanges is one of major contributory factor for unsatisfactory design of foot protection products. This paper provides a complete hardness distribution map developed by experimental testing of all the Meta tarsals and Phalanges of toes for a typical human foot. The bones were taken from two left feet of a 40 and 42 year old male cadaver. These were dehydrated prior to measurements of hardness using Leeb hardness testing method. Hardness was measured around the circumference of a bone as well as along its length. Hardness values can be related to tensile strength of the bones to predict possible values of stress that could be borne by these bones. Results may also be used for design and developing various accessories for human feet health care and comfort.

Trail runners are exposed to a high number of shocks, including high-intensity shocks on downhill sections leading to greater risk of osseous overuse injury. The type of foot strike pattern (FSP) is known to influence impact severity and lower-limb kinematics. Our purpose was to investigate the influence of FSP on axial and transverse components of shock acceleration and attenuation during an intense downhill trail run (DTR). Twenty-three trail runners performed a 6.5-km DTR (1264m of negative elevation change) as fast as possible. Four tri-axial accelerometers were attached to the heel, metatarsals, tibia and sacrum. Accelerations were continuously recorded at 1344Hz and analyzed over six sections (~400 steps per subject). Heel and metatarsal accelerations were used to identify the FSP. Axial, transverse and resultant peak accelerations, median frequencies and shock attenuation within the impact-related frequency range (12-20Hz) were assessed between tibia and sacrum. Multiple linear regressions showed that anterior (i.e. forefoot) FSPs were associated with higher peak axial acceleration and median frequency at the tibia, lower transverse median frequencies at the tibia and sacrum, and lower transverse peak acceleration at the sacrum. For resultant acceleration, higher tibial median frequency but lower sacral peak acceleration were reported with forefoot striking. FSP therefore differently affects the components of impact shock acceleration. Although a forefoot strike reduces impact severity and impact frequency content along the transverse axis, a rearfoot strike decreases them in the axial direction. Globally, the attenuation of axial and resultant impact-related vibrations was improved using anterior FSPs., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Unlabelled: Background The optimal fixation method for the first tarsometatarsal arthrodesis remains controversial. This study aimed to develop a reproducible first tarsometatarsal testing model to evaluate the biomechanical performance of different reconstruction techniques. Methods Crossed screws or a claw plate were compared with a single or double shape memory alloy staple configuration in 20 Sawbones models. Constructs were mechanically tested in 4-point bending to 1, 2, and 3 mm of plantar displacement. The joint contact force and area were measured at time zero, and following 1 and 2 mm of bending. Peak load, stiffness, and plantar gapping were determined. Results Both staple configurations induced a significantly greater contact force and area across the arthrodesis than the crossed screw and claw plate constructs at all measurements. The staple constructs completely recovered their plantar gapping following each test. The claw plate generated the least contact force and area at the joint interface and had significantly greater plantar gapping than all other constructs. The crossed screw constructs were significantly stiffer and had significantly less plantar gapping than the other constructs, but this gapping was not recoverable. Conclusions Crossed screw fixation provides a rigid arthrodesis with limited compression and contact footprint across the joint. Shape memory alloy staples afford dynamic fixation with sustained compression across the arthrodesis. A rigid polyurethane foam model provides an anatomically relevant comparison for evaluating the interface between different fixation techniques. Clinical Relevance The dynamic nature of shape memory alloy staples offers the potential to permit early weight bearing and could be a useful adjunctive device to impart compression across an arthrodesis of the first tarsometatarsal joint., Levels of Evidence: Therapeutic, Level V: Bench testing., (© 2015 The Author(s).)

Detailed knowledge of the loading conditions within the human body is essential for the development and optimization of treatments for disorders and injuries of the musculoskeletal system. While loads in the major joints of the lower limb have been the subject of extensive study, relatively little is known about the forces applied to the individual bones of the foot. The objective of this study was to use a detailed musculoskeletal model to compute the loads applied to the metatarsal bones during gait across several healthy subjects. Motion-captured gait trials and computed tomography (CT) foot scans from four healthy subjects were used as the inputs to inverse dynamic simulations that allowed the computation of loads at the metatarsal joints. Low loads in the metatarsophalangeal (MTP) joint were predicted before terminal stance, however, increased to an average peak of 1.9 times body weight (BW) before toe-off in the first metatarsal. At the first tarsometatarsal (TMT) joint, loads of up to 1.0 times BW were seen during the early part of stance, reflecting tension in the ligaments and muscles. These loads subsequently increased to an average peak of 3.0 times BW. Loads in the first ray were higher compared to rays 2-5. The joints were primarily loaded in the longitudinal direction of the bone.

Integration of patient-specific biomechanical measurements into the design of therapeutic footwear has been shown to improve clinical outcomes in patients with diabetic foot disease. The addition of numerical simulations intended to optimise intervention design may help to build on these advances, however at present the time and labour required to generate and run personalised models of foot anatomy restrict their routine clinical utility. In this study we developed second-generation personalised simple finite element (FE) models of the forefoot with varying geometric fidelities. Plantar pressure predictions from barefoot, shod, and shod with insole simulations using simplified models were compared to those obtained from CT-based FE models incorporating more detailed representations of bone and tissue geometry. A simplified model including representations of metatarsals based on simple geometric shapes, embedded within a contoured soft tissue block with outer geometry acquired from a 3D surface scan was found to provide pressure predictions closest to the more complex model, with mean differences of 13.3kPa (SD 13.4), 12.52kPa (SD 11.9) and 9.6kPa (SD 9.3) for barefoot, shod, and insole conditions respectively. The simplified model design could be produced in <1h compared to >3h in the case of the more detailed model, and solved on average 24% faster. FE models of the forefoot based on simplified geometric representations of the metatarsal bones and soft tissue surface geometry from 3D surface scans may potentially provide a simulation approach with improved clinical utility, however further validity testing around a range of therapeutic footwear types is required., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Plantar loading may influence comfort, performance and injury risk in soccer boots. This study investigated the effect of cleat configuration and insole cushioning levels on perception of comfort and in-shoe plantar pressures at the heel and fifth metatarsal head region. Nine soccer academy players (age 15.7 ± 1.6 years; height 1.80 ± 0.40 m; body mass 71.9 ± 6.1 kg) took part in the study. Two boot models (8 and 6 cleats) and two insoles (Poron and Poron/gel) provided four footwear combinations assessed using pressure insoles during running and 180° turning. Mechanical and comfort perception tests differentiated boot and insole conditions. During biomechanical testing, the Poron insole generally provided lower peak pressures than the Poron/gel insole, particularly during the braking step of the turn. The boot model did not independently influence peak pressures at the fifth metatarsal, and had minimal influence on heel loads. Specific boot-insole combinations performed differently (P < 0.05). The 8-cleat boot and the Poron insole performed best biomechanically and perceptually, but the combined condition did not. Inclusion of kinematic data and improved control of the turning technique are recommended to strengthen future research. The mechanical, perception and biomechanical results highlight the need for a multi-faceted approach in the assessment of footwear.

Objective: To investigate the reliability of a simple, efficient technique for measuring bone mineral density (BMD) in the metatarsals using dual-energy X-ray absorptiometry (DXA)., Materials and Methods: BMD of the right foot of 32 trained male distance runners was measured using a DXA scanner with the foot in the plantar position. Separate regions of interest (ROI) were used to assess the BMD of each metatarsal shaft (1st-5th) for each participant. ROI analysis was repeated by the same investigator to determine within-scan intra-rater reliability and by a different investigator to determine within-scan inter-rater reliability. Repeat DXA scans were undertaken for ten participants to assess between-scan intra-rater reliability., Results: Assessment of BMD was consistently most reliable for the first metatarsal across all domains of reliability assessed (intra-class correlation coefficient [ICC] ≥0.97; coefficient of variation [CV] ≤1.5%; limits of agreement [LOA] ≤4.2%). Reasonable levels of intra-rater reliability were also achieved for the second and fifth metatarsals (ICC ≥0.90; CV ≤4.2%; LOA ≤11.9%). Poorer levels of reliability were demonstrated for the third (ICC ≥0.64; CV ≤8.2%; LOA ≤23.6%) and fourth metatarsals (ICC ≥0.67; CV ≤9.6%; LOA ≤27.5%). BMD was greatest in the first and second metatarsals (P < 0.01)., Conclusion: Reliable measurements of BMD were achieved for the first, second and fifth metatarsals.