Low Arch Research Articles

Foot type analysis based on electronic pedobarography data in individuals with joint hypermobility syndrome/Ehlers-Danlos syndrome hypermobility type during upright standing.

Joint hypermobility syndrome/Ehlers-Danlos syndrome hypermobility type (JHS/EDS-HT) is a rheumatologic condition characterized by generalized joint hypermobility and musculoskeletal and nonmusculoskeletal findings related to congenital laxity of connective tissue. Because foot pain and other foot problems are reported to make daily life problematic to manage for individuals with JHS/EDS-HT, and thanks to the availability of modern technology, the aim of the present study was to quantitatively characterize foot type in individuals with JHS/EDS-HT during upright standing. Forty feet of 20 women with JHS/EDS-HT (mean ± SD age, 36.03 ± 14.01 years) were assessed clinically and with a pressure-sensitive mat during upright standing. Forty-five percent of feet had a high arch (pes cavus), 27.5% had a normal arch, and 27.5% had a low arch (pes planus or flatfoot). From a clinical perspective, the characterization of foot type in JHS/EDS-HT is important to identify, develop, and enhance the rehabilitative options. An understanding of the relationship between pes cavus and foot pain in these patients could, in fact, improve the clinical management of these patients.

Injury-reduction effectiveness of prescribing running shoes on the basis of foot arch height: summary of military investigations.

Secondary analysis of 3 randomized controlled trials. Objective Analysis of studies that examined whether prescribing running shoes on the basis of foot arch height influenced injury risk during military basic training. Prior to 2007, running magazines and running-shoe companies suggested that imprints of the bottom of the feet (plantar shape) could be used as an indication of foot arch height and that this could be used to select individually appropriate types of running shoes. Similar studies were conducted in US Army (2168 men, 951 women), Air Force (1955 men, 718 women), and Marine Corps (840 men, 571 women) basic training. After foot examinations, recruits were randomized to either an experimental or a control group. Recruits in the experimental group selected or were assigned motion-control, stability, or cushioned shoes to match their plantar shape, which represented a low, medium, or high foot arch, respectively. The control group received a stability shoe regardless of plantar shape. Injuries during basic training were assessed from outpatient medical records. Meta-analyses that pooled results of the 3 investigations showed little difference between the experimental and control groups in the injury rate (injuries per 1000 person-days) for either men (summary rate ratio = 0.97; 95% confidence interval [CI]: 0.88, 1.06) or women (summary rate ratio = 0.97; 95% CI: 0.85, 1.08). When injury rates for specific types of running shoes were compared, there were no differences. Selecting running shoes based on arch height had little influence on injury risk in military basic training. Prevention, level 1b.

Long-term results of aggressive hemiarch replacement in 534 patients with type A aortic dissection

To present the outcomes of routinely performed hemiarch replacement in patients with acute type A aortic dissection. From 1993 to 2013, among 629 patients with acute type A dissection, 534 patients (85%) underwent hemiarch, 63 patients (10%) underwent hemiarch and antegrade thoracic stent grafting, 26 patients (4%) underwent total arch, and 6 patients (1%) underwent isolated ascending replacement. Patients with hemiarch replacement comprised the study population. Median follow-up was 4.1 years (first quartile, 1.9; third quartile, 7.8) (2462 patient years). In-hospital mortality was 12% (66 out of 534 patients). Survival was 80% ± 2%, 68% ± 3%, and 51% ± 3%, and 84% ± 3%, 65% ± 4%, and 41% ± 6% in DeBakey type I and II patients at 1, 5, and 10 years, respectively (log rank P = .375). Freedom from distal aortic reintervention was 97% ± 1%, 90% ± 2%, and 85% ± 3% and 99% ± 1%, 97% ± 2%, and 90% ± 5% in DeBakey type I and II patients at 1, 5, and 10 years, respectively (log rank P = .046). Seven patients (1.3%) required reintervention for aortic arch aneurysm and 25 patients (5%) required reintervention for descending aortopathy. The success rate for distal reintervention performed electively or urgently was 92% (24 out of 26 patients). Marfan syndrome (odds ratio, 3.43; P = .046) and DeBakey type I dissection (odds ratio, 2.49; P = .048) were independent predictors of distal aortic reintervention. Aggressive hemiarch replacement in acute type A dissection can be performed with low mortality and low aortic arch reoperation rate. Resection of all dissected aortic wall tissue decreases, but does not eliminate, the risk of later adverse aortic events.

Foot disorders associated with overpronated and oversupinated foot function: the Johnston County osteoarthritis project.

The occurrence of musculoskeletal foot disorders differs by race and obesity, and these disorders may be related to pronated (low arch) or supinated (high arch) foot structure. This cross-sectional analysis examined relationships of foot disorders and foot function by race and obesity in a community-based observational study of adults 50+ years old with and without osteoarthritis. Members of a prospective cohort study in North Carolina were included in this analysis (N = 1466, 67.2% women, 29.5% African American, mean age 68.5 years). Foot disorders were identified with a validated assessment tool, and each foot was categorized as overpronated, oversupinated, and referent using the center of pressure excursion index from foot pressure scans during normal-paced walking. Logistic regression models estimated associations between foot function and each foot disorder with age, body mass index (BMI), gender, and race as covariates. Compared to referent, an overpronated foot was associated with hallux valgus (adjusted odds ratio [aOR] 1.36, 95% confidence interval [CI] 1.13-1.65) and overlapping toes (aOR 1.36, 95% CI 1.12-1.64), especially in the obese. An oversupinated foot was inversely associated with hallux valgus (aOR 0.85, 95% CI 0.74-0.97). An oversupinated foot was less likely to be associated with bunionettes among the obese and was more likely to be associated with plantar fasciitis in Caucasians. Foot function was related to hallux valgus and overlapping toes, especially among the obese. In clinical patients as well as in the community of older adults, treatments for both the foot disorder and the pronated/supinated foot may be needed. Level II, comparative cohort study.

Achilles tendon injury risk factors associated with running.

Research into the nature of overuse Achilles tendon injuries is extensive, yet uncertainty remains around how to identify athletes susceptible to Achilles tendon injury. To identify the strength of evidence for biomechanical risk factors associated with Achilles tendon injuries. SPORTDiscus, CINAHL, Web of Science and PubMed were searched for Achilles tendon injury risk factors and biomechanical measures which are altered in runners with Achilles tendon injuries, excluding ruptures. Fifteen articles were included in the analysis. Two variables, high vertical forces and high arch, showed strong evidence for reduced injury risk. High propulsive forces and running on stiffer surfaces may also be protective. Only one biomechanical variable, high braking force, showed clear evidence for increasing Achilles injury risk. Gait retraining to direct the centre of mass further forward to reduce high braking force could be useful in decreasing the risk of Achilles injury. The majority of biomechanical risk factors examined showed unclear results, which is likely due to the multifactorial nature of Achilles overuse injuries. Many risk factors are related to how the athlete's body interacts with the environment during gait, including ground reaction forces, muscle activity both prior to landing and immediately post ground contact, and joint motion throughout stance. Multiple risk factors have been associated with the development of Achilles tendon injuries in running athletes but most effects remain unclear. Advice for athletes recovering from Achilles tendon injuries could include avoiding soft surfaces and reducing the pace of recovery runs. Orthotic intervention could assist athletes with low arches but modification of pronation should be viewed with caution. Strength training and gait retraining could be beneficial for reducing injury risk.

Differences in Hip Strength Among Individuals With Low, Typical, and High Arches

Differences in Hip Strength Among Individuals With Low, Typical, and High Arches

Salient features of the Maasai foot: analysis of 1,096 Maasai subjects.

BackgroundThe Maasai are the most widely known African ethnic group located in Kenya and northern Tanzania. Most spend their days either barefoot or in their traditional shoes made of car tires. Although they walk long distances of up to sixty kilometers a day, they do not suffer from any foot ailments. Little is known about their foot structure and gait. The goal of this investigation was to characterize various aspects of Maasai foot in standing and walking.MethodsFoot length, calf circumference, hindfoot alignment, step length, cadence, and walking velocity were obtained from 1,096 adult Maasai people (545 males and 551 females; mean age, 40.28 ± 14.69 years; age range, 16 to 65 years). All included subjects were from rural areas, where the primary terrain was sandy soil, who spend most of their lifetime barefoot, walking. They all denied any medical history or previous symptoms related to foot problems. A trained clinician scanned all feet for deformities. Static (standing) and dynamic (walking) Harris mat footprints were taken to determine the distribution of forefoot pressure patterns during walking.ResultsThe average foot length was 250.14 ± 18.12 mm (range, 210 to 295 mm) and calf circumference was 32.50 ± 3.22 cm (range, 25 to 41 cm). The mean hindfoot alignment was 6.21° ± 1.55° of valgus. Sixty-four subjects (5.84%) had bilateral flat-shaped feet with a low medial longitudinal arch that exactly matched the broad pattern of their static footprints. Step length, cadence, and walking velocity were 426.45 ± 88.73 cm (range, 200 to 690 cm), 94.35 steps/min (range, 72 to 111 steps/min), and 40.16 ± 8.36 m/min (range, 18.20 to 63.36 m/min), respectively. A total of 83.39% subjects showed unilateral or bilateral deformities of multiple toes regardless of age. The most frequent deformity was clawing (98.79%) of which the highest incidence occurred with the fifth toe (93.23%). Dynamic footprints showed even pressure patterns throughout the forefoot (64.87%), followed by lateral forefoot pressure concentration patterns (21.81%).ConclusionsOur study shows the distinct parameters that provide more insight into the Maasai foot.

First Report of the Root-Knot Nematode Meloidogyne arenaria Infecting Noni in China.

Noni (Morinda citrifolia) is an important medicinal plant and its fruit and root are of high value. In recent years, noni has been cultivated widely on Hainan Island, China. A survey of eight commercial noni fields in four counties found that most fields had plants with symptoms consistent with damage caused by root-knot nematodes. Above-ground symptoms included reduced vigor, plant stunting, and chlorosis. Affected roots were galled, swollen, cracked, and rotten. Fruit loss associated with diseased plants was quantified as 85%. In each field, three samples were taken consisting of 15 cm wide × 20 cm deep soil (containing roots). The nematode population was extracted and quantified according to Barker (1). Nematodes were found in all soil and root samples with population densities ranging from 450 to 835 eggs and second-stage juveniles (J2s) per 200 g subsample of soil, and 685 to 985 eggs and J2s per 10 g sub-sample of fresh roots. Three single egg masses were respectively hand-picked from one sample of diseased noni roots and inoculated onto tomato plants grown with sterilized soil at 20 to 28°C in the greenhouse. After 8 weeks, nematodes were extracted from the roots of tomato plants and identified by morphology, enzyme analysis, and molecular characterization. Morphology of the female perineal patterns showed a low dorsal arch with large lateral lines separating the striae of the dorsal and ventral sectors, leading to the tail terminus; and wavy, coarse striae with forking at lateral lines and short irregular striae near the lateral lines. Enzyme analysis of the esterase phenotype was also typical of the A1 phenotype in M. arenaria. Based on the perineal pattern and esterase phenotype, the Meloidogyne species was identified as M. arenaria (Est A1) (3). Total genomic DNA was extracted from ca. 10 μl of packed second-stage juveniles (J2s) using the method of Cenis (2). The primers C2F3 (5'-GGTCAATGTTCAGAAATTTGTGG-3') and 1108 (5'-TACCTTTGACCAATCACGCT-3') (4) was used to amplify the intergenic region between COII and LrRNA genes of the mtDNA and an amplification product (1,700 bp) was obtained, similar to M. hispanica, M. incognita, and M. javanica. Root-knot nematodes (Meloidogyne spp.) have been reported to be cause disease on noni in Hawaii. However, to our knowledge, this is the first report of M. arenaria (Est A1) infecting noni in China.

Exploration of Rotation Lowering with Building RC Box-Rib Arch Bridge

Arch rib construction of Zhenzhu Bridge on the road from Wuchuan to Pengshui in Guizhou uses construction technology of vertical casting in the first place, and then vertical rotation, and the total weight of which is 610t. This paper introduces technical points and process of vertical rotation construction, and has made beneficial exploration and summary of such kind of construction technology.OverviewBridge rotation construction has advantages including saving costs for hoisting and erecting frames, reducing risks of frames losing stability when casting arch rib concrete, convenient, flexible, safe, reliable and good integrated construction operation, structural line type and internal forces are easy to adjust and control, small range requirement of construction site, and low impact on surrounding environment. Bridge rotation construction would have a broad application prospect in the practice of bridge construction, especially in Chinas southwest area with wide distribution of deep groove and dangerous gully, such construction method is more advantageous. Therefore, practice and research on such construction technology are very practical and significant.Ordinary vertical rotation construction is to have low casting or arch rib assembling, and then lift upward to reach the designed location. Concrete arch rib construction of Zhenzhu Bridge on the road from Wuchuan to Pengshui in Guizhou uses the technology of negative-angle vertical rotation construction, vertical casting arch rib, and then lowering rotation with weight of 610t. Such construction technology is used in China for the first time, while current vertical rotation of the same type of RC arch rib in China has the maximum weight. Based on emphasis on introducing construction technology characteristics of this bridge, this paper also includes innovation and beneficial exploration on the new construction technology of negative-angle vertical rotation.

A very low birth weight premature infant developing santral diabetes insipidus secondary to pituitary hemorrhage and cured successfully with intranasal desmopressin acetate

Central diabetes insipidus is characterized by polydipsia polyuria dehydration irritability poor feeding failure to thrive and hypernatremia This disease is caused by lack of antidiuretic hormone Here a very low birth weight premature infant who developed central diabetes insipidus secondary to pituitary hemorrhage in the newborn period and was treated successfully with intranasal desmopressin acetate was presented It was emphasized that desmopressin acetate might be an effective method also in the treatment of very low birth weight premature infants Turk Arch Ped 2013; 48: 241 243

Reliability and Relevance of Radiographic Measures of Metatarsus Primus Elevatus and Arch Alignment in Individuals with Midfoot Arthritis and Controls

Low arch alignment and metatarsus primus elevatus (MPE) have been postulated to increase dorsal compressive stresses in the joints of the medial column of the foot and to contribute to the development of degenerative changes. The primary purposes of this study were (1) to examine the relationship between radiographic measures of arch alignment and MPE and (2) to assess arch alignment and MPE in individuals with midfoot arthritis and in asymptomatic controls. The secondary aim was to examine the reliability of radiographic measures of arch alignment and MPE. Radiographic measures of arch height and MPE were quantified on 28 individuals with midfoot arthritis and 22 individuals in a control group. Reliability was assessed using the intraclass correlation coefficient (ICC). The Pearson product moment correlation (r) was used to assess the relationship between arch alignment and MPE. Between-group differences were assessed using a two-sample t test (α = 0.05). Good to excellent reliability was noted for measures of arch height (ICC[2,3] = 0.919-0.994) as well as MPE (ICC[2,3] = 0.891-0.882). A modest positive association was noted between normalized cortical elevation and normalized navicular height (r = 0.274, P = .030) and calcaneal inclination angle (r = 0.263, P = .035). Individuals with midfoot arthritis demonstrated lower arch alignment, reflected in a significantly higher calcaneal-first metatarsal angle (P = .002), lower calcaneal inclination angle (P = .004), and lower normalized navicular height (P < .001) compared with controls. No evidence was found to support between-group differences in lateral intermetatarsal angle (P = .495) and normalized cortical elevation (P = .146). These findings provide objective data establishing the reliability of measures of MPE and arch alignment and their potential clinical significance.

Types of Foot Arch of Adult Bangladeshi Male

Medial longitudinal arch is the most important arch of the foot from a clinical point of view. The height of the medial longitudinal arch of the foot is commonly thought to be a predisposing factor to injuries. High-arched runners exhibited more bony, ankle and lateral injuries but low-arched runners revealed a higher risk of soft tissue, knee and medial injuries. Again, both high and low-arched people had greater rearfoot eversion excursions than those with normal arch structure. This indicates the importance of measuring and determining the types of the foot arch in Bangldesh as there is no such data. The most reliable and valid way of measurement of the foot arch is the arch height index (AHI), which could be measured by the arch height index measurement system (AHIMS). The AHIMS can be costly to buy or construct for a third world country like Bangladesh. Researchers have recently developed an alternative to reduce the cost which involves the use of digital photography to assess the foot arch. The present study was done to measure and categorize the different types of the arch of foot of adult Bangladeshi males using digital photography and caliper. A total number of 110 male students of 3<SUP>rd</SUP> and 4<SUP>th</SUP> year of Sir Salimullah Medical College, Dhaka were included in the study by convenient sampling after taking approval from the Institutional Ethics Committee. In both sitting and standing position 63% of the respondents had normal arch, 21% had high arch and the rest 16% had low arch. The podiatrists and the plastic surgeons of Bangladesh may use this data to screen, diagnose and manage the pathology accordingly.

The effect of foot arch on plantar pressure distribution during standing

The aim of this study was to explore how foot type affects plantar pressure distribution during standing. In this study, 32 healthy subjects voluntarily participated and the subject feet were classified as: normal feet (n = 23), flat feet (n = 14) and high arch feet (n = 27) according to arch index (AI) values obtained from foot pressure intensity image analysis. Foot pressure intensity images were acquired by a pedopowergraph system to obtain a foot pressure distribution parameter-power ratio (PR) during standing in eight different regions of the foot. Contact area and mean PR were analysed in hind foot, mid-foot and fore foot regions. One-way analysis of variance was used to determine statistical differences between groups. The contact area and mean PR value beneath the mid-foot was significantly increased in the low arch foot when compared to the normal arch foot and high arch foot (p < 0.001) in both feet. However, subjects with low-arch feet had significantly higher body mass index (BMI) compared to subjects with high-arch feet (p < 0.05) and subjects with normal arch feet (p < 0.05) in both feet. In addition, subjects with low-arch feet had significant differences in arch index (AI) value as compared to subjects with high-arch feet (p < 0.001) and subjects with normal arch feet (p < 0.05) in both feet. Mean mid-foot PR value were positively (r = 0.54) correlated with increased arch index (AI) value. A significant (p < 0.05) change was obtained in PR value beneath the mid-foot of low arch feet when compared with other groups in both feet. The findings suggest that there is an increased mid-foot PR value in the low arch foot as compared to the normal arch foot and high arch foot during standing. Therefore, individuals with low arch feet could be at high risk for mid-foot collapse and Charcot foot problems, indicating that foot type should be assessed when determining an individual’s risk for foot injury.

Clinical Outcomes and Static and Dynamic Assessment of Foot Posture After Lateral Column Lengthening Procedure

Lateral column lengthening (LCL) has been shown to radiographically restore the medial longitudinal arch. However, the impact of LCL on foot function during gait has not been reported using validated clinical outcomes and gait analysis. Thirteen patients with a stage II flatfoot who had undergone unilateral LCL surgery and 13 matched control subjects completed self-reported pain and functional scales as well as a clinical examination. A custom force transducer was used to establish the maximum passive range of motion of first metatarsal dorsiflexion at 40 N of force. Foot kinematic data were collected during gait using 3-dimensional motion analysis techniques. Radiographic correction of the flatfoot was achieved in all cases. Despite this, most patients continued to report pain and dysfunction postoperatively. Participants post LCL demonstrated similar passive and active movement of the medial column when we compared the operated and the nonoperated sides. However, participants post LCL demonstrated significantly greater first metatarsal passive range of motion and first metatarsal dorsiflexion during gait than did controls (P < .01 for all pairwise comparisons). Patients undergoing LCL for correction of stage II adult-acquired flatfoot deformity experience mixed outcomes and similar foot kinematics as the uninvolved limb despite radiographic correction of deformity. These patients maintain a low arch posture similar to their uninvolved limb. The consequence is that first metatarsal movement operates at the end range of dorsiflexion and patients do not obtain full hindfoot inversion at push-off. Longitudinal data are necessary to make a more valid comparison of the effects of surgical correction measured using radiographs and dynamic foot posture during gait. Level III, comparative series.

Effect of ion-implantation on surface characteristics of nickel titanium and titanium molybdenum alloy arch wires

To evaluate the changes in surface roughness and frictional features of 'ion-implanted nickel titanium (NiTi) and titanium molybdenum alloy (TMA) arch wires' from its conventional types in an in-vitro laboratory set up. 'Ion-implanted NiTi and low friction TMA arch wires' were assessed for surface roughness with scanning electron microscopy (SEM) and 3 dimensional (3D) optical profilometry. Frictional forces were studied in a universal testing machine. Surface roughness of arch wires were determined as Root Mean Square (RMS) values in nanometers and Frictional Forces (FF) in grams. Mean values of RMS and FF were compared by Student's 't' test and one way analysis of variance (ANOVA). SEM images showed a smooth topography for ion-implanted versions. 3D optical profilometry demonstrated reduction of RMS values by 58.43% for ion-implanted NiTi (795.95 to 330.87 nm) and 48.90% for TMA groups (463.28 to 236.35 nm) from controls. Nonetheless, the corresponding decrease in FF was only 29.18% for NiTi and 22.04% for TMA, suggesting partial correction of surface roughness and disproportionate reduction in frictional forces with ion-implantation. Though the reductions were highly significant at P < 0.001, relations between surface roughness and frictional forces remained non conclusive even after ion-implantation. The study proved that ion-implantation can significantly reduce the surface roughness of NiTi and TMA wires but could not make a similar reduction in frictional forces. This can be attributed to the inherent differences in stiffness and surface reactivity of NiTi and TMA wires when used in combination with stainless steel brackets, which needs further investigations.

An early azhdarchid pterosaur from the Lower Cretaceous of the eastern Paris basin

Abstract A pterosaur vertebra from the Early Cretaceous (Albian) Sables verts of Grandpré (Ardennes, northeastern France) is characterised by its elongation, its very low neural arch confluent with the centrum, and the presence of a tuba vertebralis. It is referred to the family Azhdarchidae and is one of the earliest well-attested records of this group. The pterosaur diversity of the Sables verts is higher than previously recognised.

Increased plantar force and impulse in American football players with high arch compared to normal arch

BackgroundRisk of overuse injury among athletes is high due in part to repeated loading of the lower extremities. Compared to individuals with normal arch (NA) structure, those with high (HA) or low arch (LA) may be at increased risk of specific overuse injuries, including stress fractures. A high medial longitudinal arch may result in decreased shock absorbing properties due to increased rigidity in foot mechanics. While the effect of arch structure on dynamic function has been examined in straight line walking and running, the relationship between the two during multi-directional movements remains unstudied. ObjectiveThe purpose of this study was to determine if differences in plantar loading in football players occur during both walking and pivoting movements. MethodPlantar loading was examined in 9 regions of the foot for 26 participants (16 NA, 10 HA). ResultsHigh arch athletes demonstrated increased maximum force in the lateral rear foot and medial forefoot, and force time integral in the medial forefoot while walking. HA athletes also demonstrated increased maximum force in the medial rear foot and medial and central forefoot during rapid pivoting. ConclusionsThe current findings demonstrate that loading patterns differ between football players with high and normal arch structure, which could possibly influence injury risk in this population.

Treatment Planning of Implants When 3 Mandibular Posterior Teeth Are Missing

To analyze the biomechanics of 3 designs of implant treatment for 3 teeth missing in posterior low arch quadrants. A posterior portion of the human mandible missing 44, 45, 46 and three 4.1 × 10 mm threaded ITI implants with crowns were used to construct the finite element model. According to 3 implants being single, splinted or 2 implants support fixed partial denture (FPD) fixed in bone segments. Three implant support conditions were prepared with ANSYS 10.0. A load of 100 N was applied at the central fossa of the occlusal surfaces of the crowns at 45 degrees buccolingually along the triangular ridge of the buccal cusp. The von Mises stress and strain distributions in periimplant bone were observed. The results demonstrated that the von Mises stress in the supporting bone of the 2-implant supported FPD significantly increased compared with that in the 3-implant replacement. Meanwhile, when 3 implants were splinted, only the median implant had a decreased and more homogenous stress distribution, and the other implants did not exhibit significant differences when splinted. This study suggests that when space and cost permit, a 2-implant supported FPD should not be used, and 1 implant for each missing tooth being single is recommended.

A complete second metatarsal (StW 89) from Sterkfontein Member 4, South Africa

The functional anatomy of the hominin foot has played a crucial role in studies of locomotor evolution in human ancestors and extinct relatives. However, foot fossils are rare, often isolated, and fragmentary. Here, we describe a complete hominin second metatarsal (StW 89) from the 2.0–2.6 million year old deposits of Member 4, Sterkfontein Cave, South Africa. Like many other fossil foot bones, it displays a mosaic of derived human-like features and primitive ape-like features. StW 89 possesses a domed metatarsal head with a prominent sulcus, indicating dorsiflexion at the metatarsophalangeal joint during bipedal walking. However, while the range of motion at the metatarsophalangeal joint is human-like in dorsiflexion, it is ape-like in plantarflexion. Furthermore, StW 89 possesses internal torsion of the head, an anatomy decidedly unlike that found in humans today. Unlike other hominin second metatarsals, StW 89 has a dorsoplantarly gracile base, perhaps suggesting more midfoot laxity. In these latter two anatomies, the StW 89 second metatarsal is quite similar to the recently described second metatarsal of the partial foot from Burtele, Ethiopia. We interpret this combination of anatomies as evidence for a low medial longitudinal arch in a foot engaged in both bipedal locomotion, but also some degree of pedal, and perhaps even hallucal, grasping. Additional fossil evidence will be required to determine if differences between this bone and other second metatarsals from Sterkfontein reflect normal variation in an evolving lineage, or taxonomic diversity.

New data on the composition of organic matter in the hydrothermal deposits of the Mid-Atlantic Ridge (Broken Spur, Snake Pit, TAG)

773 Discovery of hydrothermal activity in the ridge zones of the World Ocean in the late 1970s allowed us to understand the importance of endogenic material during the formation of hydrothermal ores and to determine the mechanisms of abiogenic hydrothermal methane generation. The formation of organic com pounds in the zones of hydrothermal activity proceeds under the influence of a number of physicochemical and biogeochemical (extremophile consortiums of bacteria and archaea) factors [1–3]. This paper reports on study of the concentration and molecular composition of alkanic and isoprenoid hydrocarbons (HC) in hydrothermal rift zones of the Mid Atlantic ridge and reveals features of the distribu tion, genesis, and transformation of organic matter (OM). Samples of different morphologies and mineral compositions were collected using the deep manned submersible Mir 1 and Mir 2 on the 47th, 49th, and 50th voyages of the R/V Academician Mstislav Keldysh in 2002–2005. The main ore minerals of the deposits were represented by chalcopyrite, sphalerite, marca site, and pyrite. Relationships between these minerals in different hydrothermal constructions and in their individual elements are not constant and vary signifi cantly [4]. Study of the composition and HC distribution allows us to reveal the main sources of HCs and the peculiarities of the geological and geochemical trans formations under the conditions of the formation of a deep circulating system. This paper describes the results of study of HCs from hydrothermal sulfide ores of the fields Broken Spur, Snake Pit, and TAG (table). The hydrothermal field Broken Spur is located within the axial trough along the top of a low (200– 300 m) neovolcanic arch. Its activity started <1000 years ago [1]. By contrast to such mature hydrothermal fields as Snake Pit (the duration of hydrothermal ore deposition is ~4000 years) and TAG (the duration is 100 000 years) related to the type of New Data on the Composition of Organic Matter in the Hydrothermal Deposits of the Mid Atlantic Ridge (Broken Spur, Snake Pit, TAG)