Youngest Cretaceous dinosaur tracksite from the Middle East (Maastrichtian, Farrokhi Formation, Central Iran)

A late early Maastrichtian dinosaur trampling site is reported from the Farrokhi Formation of the Khur area, Central Iran. The largely indeterminate footprints, some of which may represent undertracks, can be classified as natural moulds (i.e. concave epireliefs) bordered by a raised rim of displaced sediment. They reach diameters of up to 0.5 m and were impressed under very shallow to subaerial conditions in an inter- to supratidal environment. Two generations of traces have been imprinted, initially into a soft, fine-grained carbonate sand and afterwards into a superficially hardened substrate that was still plastic underneath; the change in substrate consistency is supported by a conspicuous cracking pattern around the footprints. As a result, hardly any details of the foot morphology of the trackmakers are recorded. Nevertheless, the occurrence improves our knowledge about dinoturbation and its preservation in different kinds of substrates. Furthermore, it is the youngest record (ca. 70 Ma) of dinosaur locomotion traces from Iran and, in all probability, the entire Middle East.

Alligators employ intermetatarsal reconfiguration to modulate plantigrade ground contact

Feet must mediate substrate interactions across an animal's entire range of limb poses used in life. Metatarsals, the ‘bones of the sole,’ are the dominant pedal skeletal elements for most tetrapods. In plantigrade species that walk on the entirety of their sole, such as living crocodylians, intermetatarsal mobility offers the potential for a continuum of reconfiguration within the foot itself. Alligator hindlimbs are capable of postural extremes from a belly sprawl to a high walk to sharp turns—how does the foot morphology dynamically accommodate these diverse demands? We implemented a hybrid combination of marker-based and markerless X-ray Reconstruction of Moving Morphology (XROMM) to measure 3-D metatarsal kinematics in three juvenile American alligators (Alligator mississippiensis) across their locomotor and maneuvering repertoire on a motorized treadmill and flat-surfaced arena. We found that alligators adaptively conformed their metatarsals to the ground, maintaining plantigrade contact throughout a spectrum of limb placements with non-planar feet. Deformation of the metatarsus as a whole occurred through variable abduction (two-fold range of spread) and differential metatarsal pitching (45° arc of skew). Internally, metatarsals also underwent up to 65° of long axis rotation. Such reorientation, which correlated with skew, was constrained by the overlapping arrangement of the obliquely expanded metatarsal bases. Such a proximally overlapping metatarsal morphology is shared by fossil archosaurs and archosaur relatives. In these extinct taxa, we suggest that intermetatarsal mobility likely played a significant role in maintaining ground contact across plantigrade postural extremes.

Differences in toe flexor strength and foot morphology between wheelchair dependent and ambulant older people in long-term care: a cross-sectional study

Background Hallux valgus, lesser toe deformity, and muscle weakness of the toe flexors contribute to falls in older people. This study aimed to examine the differences in toe flexor strength and foot morphology in older people requiring long-term care due to changes in the way they mobilize in everyday life. Methods This study included 84 people aged ≥70 years without motor paralysis who underwent rehabilitation. They were divided into those who could mobilize without a wheelchair (walking group, n = 54) and those who used a wheelchair to mobilize (wheelchair group, n = 30). The presence or absence of diseases was confirmed, and hand grip strength, toe flexor strength, and foot morphology using the foot printer were measured. The presence of diseases, hand grip strength, toe flexor strength, and foot morphology were compared between the two groups. Multiple logistic analysis was performed with wheelchair dependence as the dichotomous outcome variable, and the percentages of each strength measure observed in the wheelchair group to the average hand grip and toe flexor strength measures in the walking group were compared. Results No significant between-group difference in foot morphology was found. The factors related to the differences in ways of ambulating in daily life were history of fracture, heart disease, and toe flexor strength. After comparing the muscle strength of the wheelchair group with the mean values of the walking group, we found that the toe flexor strength was significantly lower than the hand grip strength. Conclusions Older people who used a wheelchair to mobilize have significantly less toe flexor strength than those who do not despite no significant difference in foot morphology. Use of a wheelchair is associated with a reduction in toe flexor strength.

Sensorimotor deficits in distance runners with medial plantar pain

ABSTRACTContextMedial plantar pain is a complex and multifactorial condition experienced by some distance runners, which makes etiological differentiation and diagnosis challenging.ObjectiveTo assess plantar sensation, pain perception and sensitivity, intrinsic foot strength, and foot morphology before and after a 9.7 km run in long-distance runners with and without medial plantar pain.DesignDescriptive laboratory studySettingLaboratory.PatientsSeven distance runners with medial plantar pain (four males, three females; aged 22.3±3.7 years; BMI 22.3±3.5 kg/m2) and seven matched healthy controls (four males, three females; aged 20.3±1.0 years; BMI 22.0±1.7 kg/m2) were recruited from a public university.Intervention(s)Participants ran a six-mile course in their own footwear at a self-selected pace.Main Outcome MeasuresPain visual analogue scale (VAS), pressure pain thresholds (PPT), plantar sensation, foot morphology, weight-bearing dorsiflexion (WBDF), forefoot joint mobility, toe flexion, intrinsic foot muscle strength, and a seated neural provocation test were analyzed pre-and post-run utilizing mixed model group by time ANOVAs, post hoc effect size point estimates, and 95% confidence intervals.ResultsA significant group by time interaction was observed for PPT at the mid-arch (Control: pre: 83.0±27.4N, post: 79.5±22.6N; Symptomatic: pre: 90.5±31.9N, post: 70.1±32.7 N; p=.03) and posterior tibialis (PT) (Control: pre: 75.7±19.5 N, post: 65.7±14.2N; Symptomatic: pre: 75.8±20.4 N, post: 51.1±11.9 N; p=.05) sites. PPT in the posterior tibialis significantly decreased in the symptomatic group following the run (ES=1.5, 95% CI: 0.3, 2.7). Both groups demonstrated significantly decreased plantar sensation thresholds at the base of the 5th metatarsal (p=.04), PPT at the calcaneal tuberosity (p=.001), and increased TMT extension (p=.01) and WBDF (p=.01) following the run.ConclusionsThe etiology of medial plantar pain observed in our sample was likely attributed to central sensitization and running-induced sensory changes. Clinicians should include sensorimotor testing when managing patients with medial plantar pain.Key PointsMedial plantar pain is a unique pathologic entity that has not been previously well described and likely caused by central sensitization. Clinicians should include sensorimotor testing and interventions when managing patients with medial plantar pain.