This Voodoo Biomechanics vignette touches on the limitations of the Foot Posture Index (FPI) when used to infer mechanical function, arguing that it is widely misinterpreted in clinical practice. The FPI is a static, descriptive tool that measures foot shape during relaxed standing, classifying feet as pronated, neutral, or supinated. However, functional stiffness, which is the foot's resistance to deformation, is a dynamic mechanical property that only emerges under load and during gait. Consequently, the FPI cannot define functional stiffness or predict dynamic mechanical behavior because static posture is a poor predictor of kinetics. The FPI remains useful for communication and documentation but should not be used as a functional classifier, particularly as biomechanics shifts toward kinetic explanations of foot behavior.

This podcast presents a conceptual synthesis and narrative review that challenges the deeply ingrained principle in podiatric biomechanics equating foot pronation with flexibility and supination with rigidity. It argues that functional stiffness should be redefined as a load-dependent kinetic state that emerges dynamically during gait, rather than a fixed mechanical property inferred from kinematic posture. Drawing on advanced multi-segment foot models and engineering principles, the presenters assert that a foot's resistance to deformation is task- and phase-dependent, meaning a foot can be visibly pronated yet mechanically stiff, or supinated yet compliant. Ultimately, the review advocates for a shift in clinical reasoning from geometry-based interpretations toward load-based interpretations of foot function, which better explains clinical observations and the variable success of orthotic interventions.

This podcast provides a detailed overview of gait initiation, explaining that the simple act of taking a first step requires an intricate sequence of neural and biomechanical processes. The presenters highlights the earliest neural planning through the Bereitschaftspotential (BP) in the cortex, followed by critical anticipatory postural adjustments (APAs) that intentionally destabilize the body’s center of mass to allow forward motion. Crucially, the text emphasizes the functional relationship between the ankle muscles—specifically the inhibition of the soleus and the subsequent activation of the tibialis anterior—as the mechanical trigger for stepping. Finally, details of how various neurological and traumatic conditions commonly disrupt this highly coordinated BP–APA–ankle synergy, making gait initiation a clinically sensitive marker for neuromuscular health, particularly for podiatrists involved in patients with neurological disorders.

MTSS is categorically a tibial bone-stress injury, a position supported by a synthesis of modern evidence. This redefinition is built upon histopathology and imaging studies that show bone-stress pathology rather than periosteal inflammation, and confirmed by in vivo tibial strain data that identifies MTSS symptoms occurring on the tensile (bending) side of the tibia. Furthermore, the anatomical location and biomechanical risk factors of MTSS are consistent with excessive bone bending load, not muscle-tendon traction. The overwhelming scientific data supports MTSS’s place on the bone-stress continuum, similar to an early stress fracture.

This podcast re-evaluates Medial Tibial Stress Syndrome (MTSS) through a kinetic lens, asserting that the injury is a bone-stress pathology driven primarily by excessive varus tibial bending leading to dangerous tensile loads on the medial tibial cortex. The content argues that the traditional orthotic approach, which focuses on controlling foot pronation (a kinematic correlate), fails to address the underlying kinetic problem of the medialized location of the ground reaction force (GRF) relative to the tibial shaft. Conventional anti-pronation devices, such as those employing varus posting, are criticized for potentially exacerbating the injury because they often inadvertently shift the GRF further medially, increasing the very bending moment associated with MTSS. Accordingly, the author proposes an alternative kinetic orthotic strategy grounded in mechanical evidence, which aims to directly reduce tibial stress by employing material stiffness to lateralize the GRF and reduce overall midfoot impulse. This shift from a kinematic to a kinetic paradigm offers a more mechanically coherent path forward for managing MTSS compared to historically relied-upon pronation-control methods.

Why is your injured patient not getting better?

This little detour from the SHIFT project outlines an evidence-based strategy for how targeted nutritional strategies can support the recovery of muscle and tendon tissues following injury. The article distinguishes between muscle repair, which requires robust dietary protein for synthesizing contractile proteins like actin and myosin, and tendon healing, which relies on the complex formation of Type 1 collagen. The author stresses that Vitamin C is chemically essential for key steps in collagen synthesis, and notes that supplemental collagen peptides can provide the necessary amino acids less common in typical diets. Furthermore, components like Omega-3 fatty acids and Curcumin are recommended to help modulate inflammatory responses during the initial healing phases. The presentation concludes by detailing comprehensive, phase-specific nutritional recommendations, providing clinicians with pragmatic dosing guidelines for protein, vitamins, and supplements across the inflammatory, proliferative, and remodeling stages of recovery.

This podcast presents a kinetic paradigm for understanding lateral ankle instability (LAI), arguing that the condition is fundamentally a force-moment timing problem rather than an issue of alignment, ligament laxity, or primary muscle weakness. Instability occurs because the a high magnitude inversion moment from ground reaction forces (GRF) rises much faster than the internal eversion moment generated by the peroneal-ligament complex can oppose it, usually within the first 40 milliseconds of stance. The presenters emphasizes that neuromuscular timing, specifically impaired feed-forward readiness (anticipatory pre-activation), is a central deficit, as reflexive responses are too slow to prevent injury. Effective management strategies involve modulating GRF using material stiffness (stiffer lateral heel/softer medial heel) and addressing factors like internal supination loads from a tight gastrocnemius–soleus complex to restore the crucial kinetic balance. Finally, the source cautions against relying on wedging to change GRF, which forces motion, in favor of methods that directly modify forces and improve timing.

This presentation critically examines the medial heel skive (MHS), an orthotic modification introduced by Dr. Kevin Kirby in 1992 to improve pronation control, particularly for patients with medially deviated subtalar joint axes. Although the MHS has been widely adopted by both clinicians and the orthotic industry, its foundational claim—reducing rearfoot pronation by increasing the supination moment across the STJ axis—has never been empirically verified by rigorous scientific research over the past three decades. The only mechanical assessment demonstrated that increasing the skive depth resulted solely in a localized pressure spike due to the medial force on a reduced contact area, not an increase in vertical force or a shift in the center of pressure. Ultimately, the paper concludes that the MHS remains an unvalidated, theoretical geometric modification that has become entrenched in practice through cultural inertia rather than established scientific evidence, a problem compounded by issues with reproducibility in both traditional and digital foot orthosis manufacturing.