Splayfoot: Causes of Forefoot Pain and Calluses on the Metatarsus

Underlying mechanics

The human foundation is a biomechanical masterpiece consisting of 26 bones, numerous joints, ligaments, and muscles. In a healthy state, the forefoot possesses two defining arch structures: the longitudinal arch on the inner side of the foot and the transverse arch (Arcus pedis transversus) at the level of the metatarsal heads (Capita ossium metatarsi). The transverse arch spans like an elastic bridge across the ball of the foot from the first to the fifth metatarsal bone.

In healthy foot statics, the first metatarsal head beneath the big toe and the fifth metatarsal head beneath the little toe bear the primary load during heel strike and toe-off. The middle metatarsal heads two, three, and four float slightly elevated above the ground. Dense ligamentous tissue, particularly the deep transverse metatarsal ligament (Ligamentum metatarsale transversum profundum), along with short intrinsic foot muscles such as the adductor hallucis muscle (Musculus adductor hallucis), maintain the tension of this arch.

If the ligamentous apparatus relaxes or the intrinsic foot muscles weaken, the transverse arch collapses. The metatarsal bones splay outward and downward. As a result, the middle metatarsal heads push downward and touch the ground directly during walking. The forefoot becomes visibly wider.

Due to this collapse, the foot loses its shock-absorbing function. The biological reaction of the tissue is swift: under continuous strain, the skin develops a protective hyper-reactivity of keratinisation. Widespread hyperkeratoses form to safeguard the underlying deeper tissue from immense pressure and shear forces.

Typical signs

The cardinal symptom of a splayfoot is weight-bearing pain in the forefoot area, medically referred to as metatarsalgia. Those affected often describe this pain as a deep burning sensation or as the feeling of walking on hard objects. The pain typically intensifies after walking long distances or standing for extended periods on hard surfaces.

A visible characteristic is the formation of calluses directly beneath the second and third metatarsal heads. Unlike normal callosities that are evenly distributed, these hyperkeratoses concentrate in circular or oval patterns on narrowly defined pressure points. Painful, deep keratin cones frequently form in the centre of these calluses, which are often mistaken for classic corns.

In addition to skin changes, the deformity manifests as a visible change in toe architecture. The loss of the transverse arch alters the angle of pull of the long toe tendons. This frequently leads to the development of hammer toes or claw toes, in which the toe joints remain permanently flexed. The onset of a hallux valgus is also significantly promoted by the splayfoot component.

Differential diagnosis includes distinguishing splayfoot from other forefoot disorders. Plantar fasciitis primarily causes pain at the heel base and longitudinal arch, especially in the morning after getting out of bed. Conversely, a march fracture (stress fracture of a metatarsal bone) presents as sudden, pinpoint pressure pain over the bone shaft, often accompanied by marked swelling of the dorsum of the foot.

Morton's neuroma is another important differential diagnosis. This involves a benign thickening of the plantar nerves between the metatarsal heads, most commonly in the third interdigital space. Those affected experience a sudden, shooting pain similar to an electric shock, which is often accompanied by numbness in the adjacent toes.

Everyday causes

The development of a splayfoot is rarely attributable to a single cause, but rather results from an interplay of various strain factors. Modern footwear plays a central role in this context. High-heeled shoes shift the body's centre of gravity forward and multiply the weight resting on the metatarsal heads. Shoes with a toe box that is too narrow squeeze the toes together, preventing the intrinsic foot muscles from actively working and strengthening.

Similarly, continuously walking on flat, unyielding surfaces such as asphalt, tiles, or laminate floorings has a negative impact. The foot receives no natural stimuli that would require activation of the delicate foot muscles. The muscles gradually atrophy, while the ligamentous tissue progressively stretches out.

Genetic factors and constitutional connective tissue weakness play a significant role. Statistically, women are affected significantly more often than men due to higher hormone-induced connective tissue elasticity. Pregnancy can also cause a lasting collapse of the transverse arch through the release of the hormone relaxin combined with rapid weight gain.

Conditions such as rheumatoid arthritis lead to destruction of the capsular-ligamentous apparatus due to inflammatory processes in the metatarsophalangeal joints. Neurological disorders or progressive polyneuropathy also alter the gait pattern so severely that abnormal loading occurs in the forefoot region. An age-related reduction of the plantar fat pad beneath the metatarsal heads further exacerbates the pressure problem, as the natural cushioning diminishes.

When medical evaluation is necessary

Although a podiatry practice is a key point of contact for symptom relief and care, certain warning signs require immediate orthopaedic or specialist medical diagnosis. Sudden onset of pain without prior overuse requires excluding a stress fracture. Redness, localised heat, and swelling on the dorsum of the foot indicate inflammatory processes.

Open wound surfaces or weeping fissures within calloused areas are absolute warning signs. People with diabetes mellitus or peripheral arterial disease require immediate specialist medical evaluation for any skin damage to minimise the risk of diabetic foot syndrome. In our practice, as a specialised /en/sectoral-practitioner, we provide qualified advice on the necessary steps.

If numbness, tingling, or persistent abnormal sensations occur in the toes, a neurological examination is indicated. In the case of progressive joint stiffness in the metatarsophalangeal joints, diagnostic imaging using X-rays or magnetic resonance imaging can provide clarity.

What podiatric treatment can achieve

Professional podiatric treatment aims to gently reduce mechanical pressure peaks, prevent tissue damage, and restore a pain-free quality of life in daily routine. The initial visit begins with a thorough medical history and a visual inspection of foot statics and skin condition.

At the core of symptom-oriented therapy is the painless and tissue-sparing debridement of hyperkeratoses. Using sterile scalpel blades, the podiatrist removes excess calloused material layer by layer. The edges are then smoothed using high-speed rotating diamond burs to create a smooth, homogeneous skin surface. This treatment is performed in strict compliance with all specifications of our certified /en/hygiene standards.

To immediately relieve pressure on the irritated metatarsal heads following callus removal, custom-made pressure-relief elements are used. A highly effective method is the application of temporary felt or foam padding (feltings), which distributes pressure away from the painful metatarsal head. For lasting relief, we fabricate customized silicone orthoses that are precisely adapted to the geometry of the foot. Details regarding our therapy options can be found under /en/services.

Podiatric measures also include individualized advice on suitable footwear and medical orthotics. Orthotics featuring an integrated retrocapitar pad gently elevate the collapsed transverse arch from below, effectively relieving the second to fourth metatarsal heads. The duration of a complex podiatric session is typically 30 to 45 minutes. Depending on the intensity of keratinisation and physical strain, treatment intervals of four to six weeks are recommended.

What you can do yourself

Sustainable improvement of symptoms requires your active cooperation in daily life. Targeted exercises and adjustments to your habits can slow the progression of arch collapse and strengthen the foot musculature.

1. Perform short daily sessions to activate the intrinsic foot muscles. Sit on a chair and try picking up small objects such as marbles, pencils, or a small cloth from the floor using only your toes, then put them down again. Another highly effective exercise is the so-called short foot exercise according to Janda: gently pull the metatarsophalangeal joint of the big toe toward the heel without curling the toes, actively tensing the longitudinal and transverse arches.
2. Regularly stretch the calf muscles (Musculus gastrocnemius and Musculus soleus). Shortened calf muscles limit dorsiflexion in the ankle joint, causing the foot to roll over the forefoot prematurely during walking, placing extreme load on the metatarsal heads. To stretch, take a lunge stance facing a wall and press the rear heel firmly against the floor.
3. Take every opportunity to walk barefoot on natural, uneven surfaces such as grass, sand, or forest soil. This stimulates the proprioceptors of the plantar surface and strengthens the coordinative capabilities of the stabilizing muscles.
4. When purchasing shoes, consistently ensure a sufficiently wide toe box in which your toes can lie flat side by side. Avoid heels over two centimetres in height whenever possible and choose shoes with a flexible, well-cushioned sole.

Common mistakes

In clinical practice, we repeatedly observe well-intentioned self-treatment attempts that worsen the problem or introduce additional risks.

1. Using callus rasps, corn shavers, or blades from drugstores often leads to microscopic injuries to the skin. The skin responds to this excessive stimulus by producing callus even faster and thicker, initiating a vicious circle.
2. Over-the-counter corn plasters are dangerous when used on pressure calluses beneath the metatarsal heads. These plasters contain highly concentrated salicylic acid, which liquefies calloused material. However, the plaster frequently shifts and chemical burns occur on the healthy surrounding tissue, resulting in deep wounds prone to infection.
3. Simply treating the callus without simultaneously correcting the cause remains ineffective. Removing calluses while continuing to wear narrow, high-heeled shoes or omitting pressure-relieving orthotics will not achieve long-term freedom from discomfort.
4. Purchasing prefabricated soft-foam insoles from supermarkets without professional guidance rarely helps. If the position of the incorporated pad does not match your individual anatomy precisely, pressure on the metatarsal heads may even increase, or a nerve may become pinched.

Scientific evidence and clinical perspective

Scientific literature demonstrates a close link between altered foot pressure patterns and the onset of forefoot pain. A biomechanical study by Kang et al. showed that the collapse of the transverse arch leads to a significant shift of peak pressure values from the big toe region to the middle metatarsal heads [1].

Regarding therapeutic interventions, clinical studies confirm the benefit of combined treatment approaches. A systematic review by Mickle et al. investigated the efficacy of custom-made orthopaedic insoles for forefoot pain and found that retrocapitar pressure relief can reduce peak plantar pressure under the metatarsal heads by up to 35 percent [2].

Studies on basic podiatric care by Boulton et al. emphasize the necessity of professional debridement. Regular, painless removal of thick hyperkeratoses not only reduces pain intensity immediately after treatment, but also normalises gait and significantly reduces the risk of local tissue trauma [3].

Regarding active therapy, a study by Gooding et al. demonstrated that targeted training of the intrinsic foot muscles over an eight-week period measurably increases the cross-sectional area of the foot muscles and improves arch stability under load [4]. Finally, a biomechanical analysis by Carl et al. proved that a heel height of just four centimetres increases pressure on the metatarsal heads by more than 50 percent, scientifically highlighting the importance of proper footwear selection [5].

Treatment in Memmingen

At our practice FREITAG® Podologie GmbH at Kempterstr. 25 in Memmingen, we offer patients from Unterallgäu, Allgäu, and Upper Swabia sound, individually tailored podiatric care. Under the professional direction of Helga Maria Freitag, we combine modern podiatric expertise with precise craftsmanship. Learn more about our approach under /en/practice.

We thoroughly analyze your foot statics, gently remove bothersome calluses, and develop suitable pressure-relief concepts for your daily life. We look forward to meeting you in person. Feel free to /en/contact us directly to schedule an appointment.

Biomechanical cascade: Possible long-term consequences of untreated splayfoot

If mechanical overpressure under the metatarsal heads is ignored over years, it is not only the skin surface that suffers. The ongoing abnormal strain sets off a biomechanical cascade that damages deeper structures of the forefoot. A common secondary reaction is inflammation of the bursae beneath the joint capsules, medically known as submetatarsal bursitis. This fluid-filled cavity swells and intensifies the sensation of walking on a hard foreign body. Due to permanent overstretching of the capsular-ligamentous apparatus, the plantar plate also progressively loses its stabilizing function.

The plantar plate is a thick, fibrocartilaginous structure beneath the metatarsophalangeal joint that prevents excessive hyperextension. Strains or degenerative tears in this tissue layer lead to instability of the metatarsophalangeal joints. In advanced stages, the toes not only deviate laterally, but subluxate or dislocate dorsally over the metatarsal head. A typical consequence is the formation of a crossover toe, where the second toe painfully overlaps the big toe.

An anonymised case example illustrates this progression. A 62-year-old female patient consulted the practice after experiencing forefoot pain for several years, which she had initially attempted to manage independently using over-the-counter pads. Inadequate pressure relief resulted in a tear of the plantar plate at the second metatarsophalangeal joint, accompanied by a pronounced deformity. Only a combination of pressure-relieving orthotic therapy, targeted podologische Komplexbehandlung (comprehensive podiatric treatment), and orthopaedic insole provision restored her daily load capacity.

Strain profiles in occupational everyday life and sports

Certain occupational groups and sports subject the forefoot to extreme forces, significantly accelerating the development of a splayfoot deformity. In standing professions such as nursing, gastronomy, or retail, employees often spend eight to ten hours a day on hard industrial floors. If footwear lacks functional cushioning, the cumulative impact load adds up to several tonnes per working day. Furthermore, mandatory S3 safety footwear hinders natural foot mechanics. Their puncture-resistant soles and steel toe caps fix the foot in a rigid position, severely restricting the activity of the intrinsic foot muscles.

In running as well as jumping or stop-and-go sports like tennis or handball, forces reaching three to four times the body weight act on the foot with every ground contact. Running on paved surfaces subjects the collapsed metatarsal heads to this unbuffered impulse load. If running shoes lack sufficient width in the forefoot area, the metatarsal bones are compressed further. This frequently leads to irritation of the interdigital nerves and the formation of accompanying tissue oedema.

For athletically active individuals, a detailed gait analysis and adjustment of athletic footwear are therefore essential. Transitioning to shoes with a wider toe box and a moderate heel drop can measurably improve pressure distribution across the ball of the foot. However, a sudden shift to pure barefoot shoes should be avoided, as the damaged tissue will be overwhelmed by the abrupt increase in strain without gradual adaptation.

Functional diagnostics and material science of modern orthotics

Adequate treatment of a splayfoot requires far more than simply inserting a prefabricated insole. Precise reconstruction of the arch bridge requires thorough biomechanical functional diagnostics. While a simple foam impression merely provides a static image of the plantar surface, dynamic pedobarography captures pressure distribution throughout the entire roll-off movement. Sensor mats measure with millimetre precision which points of the forefoot experience peak pressures at each phase of the stride.

Based on these measurements, custom orthopaedic insoles are constructed using multi-layered materials. Material selection strictly depends on body weight, activity level, and pain intensity. Ethylene-vinyl acetate (EVA) foams with varying degrees of hardness, measured in Shore hardness between 30 and 60, enable a targeted combination of cushioning and stability. Thermoplastic materials and carbon fibres serve as a supporting base to elastically support the longitudinal and transverse arches without completely inhibiting the natural torsion of the foot. Soft padding materials made of memory foam or cushioning gels relieve sensitive pressure points directly under metatarsal heads two to four.

The crucial element of a splayfoot orthotic is the retrocapitar pad, a teardrop- or butterfly-shaped elevation. This corrective aid must be placed precisely behind, and under no circumstances directly beneath, the metatarsal heads. Pads incorrectly positioned under the heads dramatically increase local pressure and exacerbate pain symptoms. When placed correctly, the pad gently elevates the bone shafts, allowing the metatarsal heads to return to their original, slightly elevated floating position.