Sesamoiditis: Causes, Symptoms and Treatment

Sesamoiditis is an inflammatory condition affecting the two small sesamoid bones embedded in the flexor hallucis brevis tendons beneath the first metatarsal head, at the base of the big toe. The sesamoid bones function as pulleys, providing a smooth surface for tendons to slide across while increasing the ability of those tendons to transmit muscle forces during movement. Sesamoiditis develops when repetitive stress overloads the tendons surrounding the sesamoids, triggering persistent inflammation at the forefoot's weight-bearing zone.

Sesamoiditis causes range from high-impact activities (dancing, running, and baseball catching) to poor footwear choices, high-arched foot structure, and excessive body weight, all of which concentrate abnormal pressure on the forefoot. Symptoms present as gradual-onset pain at the ball of the foot beneath the big toe, accompanied by tenderness, localized swelling, and restricted toe movement. Diagnosis combines physical examination with imaging (X-ray, MRI, and CT scan) to confirm inflammation and rule out sesamoid fracture. Treatment progresses from rest, ice, and anti-inflammatory medication through orthotic offloading pads, corticosteroid injections, and, in rare cases, surgical sesamoid removal. Understanding the causes, symptoms, and treatment pathways of sesamoiditis enables earlier intervention, reduces recovery time, and prevents long-term forefoot damage from chronic tendon overload.

What is Sesamoiditis?

Sesamoiditis is a form of tendinitis characterized by irritation and inflammation of the tendons surrounding the sesamoid bones, two small bones located under the big toe joint on the plantar surface of the foot. Each sesamoid is approximately the size of a corn kernel, and together the tendons assist with weight-bearing and help elevate the bones of the big toe during locomotion. Inflammation develops when repetitive mechanical stress exceeds the tendons' capacity to recover, producing a progressive overuse injury concentrated at the forefoot's most load-bearing zone.

The two semilunar-shaped sesamoid bones are located within the flexor hallucis brevis tendon, with the medial bone designated as the tibial sesamoid and the lateral bone as the fibular sesamoid. Pain from sesamoiditis builds gradually, beginning as a dull ache beneath the big toe joint before intensifying into sharp, persistent discomfort during walking and weight-bearing. Sesamoiditis is common among ballet dancers, runners, and baseball catchers due to the high forefoot loading demands placed on the sesamoid tendons during the specific movement patterns the activities require.

How is a Calcaneal Spur Different From Sesamoiditis?

A calcaneal spur and sesamoiditis are distinct conditions that affect separate anatomical structures, separate bones, and separate regions of the foot. A calcaneal spur is a bony outgrowth from the calcaneal tuberosity, forming on the heel bone's inferior or posterior surface as calcium deposits accumulate in response to chronic plantar fascia stress. Sesamoiditis, by contrast, involves tendon inflammation surrounding the two small sesamoid bones embedded in the forefoot beneath the big toe joint, with no bony outgrowth or calcium deposition as part of its pathology.

The anatomical distance from the heel to the ball of the foot separates the two conditions completely. A calcaneal spur produces pain at the heel's base, while sesamoiditis concentrates pain at the forefoot's medial plantar surface. Sesamoiditis causes pain at the ball of the foot near the big toe joint, resulting from repetitive stress and overuse of the two small sesamoid bones. Clinically, a calcaneal spur is confirmed through lateral X-ray imaging of the heel, whereas a sesamoiditis diagnosis focuses on the first metatarsophalangeal joint, making the two conditions both anatomically and diagnostically separate. The Calcaneal Spur article covers the specific mechanisms and management strategies of that distinct condition, for a detailed breakdown of heel bone pathology.

Are Sesamoiditis the Same as Bone Spurs in the Heel?

No, sesamoiditis is not the same as bone spurs in the heel. Sesamoiditis is a form of tendinitis involving inflammation of the tendons surrounding the sesamoid bones beneath the big toe joint on the forefoot's plantar surface. A bone spur in the heel, known as a calcaneal spur, is a bony outgrowth from the calcaneal tuberosity that forms when calcium deposits accumulate on the heel bone's surface in response to chronic stress.

The two conditions differ structurally, anatomically, and pathologically. A heel bone spur is a structural deformity, an abnormal bony projection, whereas sesamoiditis is an inflammatory soft tissue condition with no bony growth involved. Location separates them further, with the heel bone spurs forming at the calcaneus at the rear of the foot, while sesamoid pathology affects the forefoot. Unlike the heel spur that forms on the heel bone, sesamoid-related conditions develop near the big toe joint in the forefoot area. The Bone Spurs is a broader term encompassing abnormal bony projections at any skeletal site, none of which share sesamoiditis's tendon-inflammation mechanism.

What Causes Sesamoiditis?

The causes of sesamoiditis are listed below.

• Repeated Strain on the Plantar Flexor Tendons: Chronic overloading of the flexor hallucis brevis tendons surrounding the sesamoids triggers progressive inflammation at the forefoot's weight-bearing zone. Sesamoiditis results from the overuse of the tendons involved with the small bones in the front of the foot.
• Plantar Fasciitis: Persistent plantar fascia tension alters forefoot load distribution, increasing compressive forces on the sesamoid bones during the push-off phase of gait and aggravating surrounding tendon tissue.
• High-Impact or Repetitive Activities (running, jumping, prolonged standing): Sesamoiditis is common among dancers, joggers, and people who frequently wear high heels, as the activities place sustained forefoot pressure on the sesamoid bones.
• Poor Footwear (lack of support or cushioning): Tendons surrounding the sesamoids become inflamed when the tendons experience repeated trauma from wearing high heels or poorly fitting shoes.
• Abnormal Foot Mechanics (flat feet, high arches, gait issues): Dancers, joggers, and people with high-arched feet or bunions develop pain at the sesamoids beneath the first metatarsal head due to the concentrated forefoot pressure their foot structure produces.
• Aging (reduced tissue flexibility, thinning heel pad): Reduced tendon elasticity and decreased plantar fat pad thickness with age lower the forefoot's capacity to absorb impact, making the sesamoid tendons more vulnerable to repetitive stress injury.
• Excess Body Weight: Increased body mass elevates ground reaction forces at the forefoot during walking, raising the compressive load transmitted through the sesamoid bones with each step and accelerating tendon irritation.

Why do Calcium Deposits Form on the Heel Bone?

Calcium deposits form on the heel bone through a reparative biological response triggered by chronic mechanical stress at the plantar fascia's calcaneal attachment point. Calcium deposits build up on the bottom of the heel bone when a foot is exposed to constant stress, and repeated damage causes the deposits to accumulate on each other, forming a spur-shaped deformity.

The process begins with repetitive micro-tearing of soft tissue fibers at the calcaneal insertion, activating an osteoblastic repair response that deposits calcium salts at the stressed site. Accumulated mineral hardens progressively over 6 to 12 months of sustained strain into a detectable bony projection. Chronic traction at the insertion of the plantar fascia into the calcaneum leads to inflammation and subsequent ossification, a process referred to as enthesitis. Predisposing factors (obesity, flat feet, and prolonged standing on hard surfaces) perpetuate the mechanical stimulus that drives continued calcium accumulation at the heel bone's vulnerable attachment zone.

Can Repeated Strain Lead to Sesamoiditis?

Yes, repeated strain leads to sesamoiditis by progressively overloading the flexor tendons surrounding the sesamoid bones beyond their capacity for timely repair. The sesamoid bones become irritated and inflamed along with the tendons, producing sesamoiditis due to too much stress.

The high-impact step, jump, or toe-off motion transmits compressive and tensile forces through the sesamoid tendons. Cumulative micro-trauma from sustained repetitive loading generates persistent inflammation at the tendon-bone interface beneath the first metatarsal head. Disrupted blood supply to the sesamoid bones, a condition called osteochondritis, leads to calcium deposition near the bones and consequent tendon inflammation. Individuals engaged in activities (ballet, distance running, and basketball) that demand repetitive forefoot loading face elevated sesamoiditis risk, as the activity's mechanical demands exceed the tendons' recovery capacity when adequate footwear support and load management are absent.

What are the Symptoms of Sesamoiditis?

The common symptoms of sesamoiditis are listed below.

• Pain: The most common symptom of sesamoiditis is pain in the ball of the foot, specifically under the joint of the big toe, which builds slowly until walking becomes too painful. Pain intensity ranges from a dull ache in early-stage cases to sharp, stabbing discomfort rated 5 to 8 out of 10 on the numeric pain scale in moderate-to-severe presentations.
• Tenderness: Direct palpation over the sesamoid bones beneath the first metatarsal head reproduces localized sensitivity, with the tibial (medial) sesamoid more frequently affected than the fibular (lateral) sesamoid during clinical examination.
• Inflammation: Mild warmth and swelling occasionally accompany sesamoiditis, with redness extending medially and appearing to involve the first metatarsophalangeal joint during active inflammatory episodes.
• Warmth: Mild heat over the forefoot at the sesamoid site reflects increased local blood flow from the inflammatory response, occurring alongside swelling during periods of heightened tendon irritation.

What does Sesamoiditis Pain Feel Like?

Sesamoiditis pain feels like a sharp, throbbing ache localized at the ball of the foot beneath the big toe joint, intensifying progressively with continued weight-bearing activity. The pain is sharp and throbbing in character, causing limitation in dorsiflexion and plantar flexion of the first metatarsophalangeal joint, beginning mildly and worsening when strained activity continues.

Pain follows a gradual onset pattern, starting as low-grade forefoot discomfort during activity before advancing to persistent soreness that persists through rest periods in moderate cases. The pain tends to build gradually, with noticeable swelling or bruising accompanying it, and sesamoiditis makes it difficult to straighten or bend the big toe. A popping sensation at the big toe during walking indicates acute tendon irritation around the sesamoid. Pain reduction occurs during extended rest, but the discomfort resumes immediately upon resuming forefoot loading, reflecting the condition's mechanical and inflammatory nature rather than a purely structural problem.

Are Sesamoiditis Always Painful?

No, sesamoiditis is not always painful, as the condition's symptom severity depends on the degree of tendon inflammation, activity level, and individual pain threshold at the time of diagnosis. Mild cases with early-stage inflammation produce only intermittent forefoot discomfort during high-impact activity, resolving with brief rest without producing persistent pain at baseline. The pain is immediate in its absence if a fracture in the sesamoid bones accompanies sesamoiditis. The discomfort builds slowly and in some cases remains manageable for extended periods.

Subclinical sesamoiditis, where tendon irritation is present without significant inflammatory cascade activation, produces minimal symptoms that go unrecognized until activity demands increase. Sesamoiditis pain may come and go depending on the activity, with some presentations remaining intermittent rather than constant. Continued overloading of asymptomatic sesamoid tendons without intervention accelerates tissue damage and converts a low-pain presentation into a chronic, disabling condition over time.

Where is Sesamoiditis Pain Located?

Sesamoiditis pain is located at the ball of the foot, directly beneath the first metatarsal head at the base of the big toe, on the plantar (bottom) surface of the forefoot. Pain is located in the ball of the foot in sesamoiditis of the hallux, especially on the medial side, with tenderness corresponding exactly to the location of the medial sesamoid bones.

Pain concentrates at the point of maximum sesamoid loading during toe-off in the gait cycle, where the forefoot accepts and transmits propulsive forces from the ground through the big toe joint. The medial (tibial) sesamoid sustains the greatest compressive and tensile loads during normal walking, making it the more frequently symptomatic of the two sesamoid bones. Tenderness is localized to a sesamoid during clinical examination, usually the tibial sesamoid, with hyperkeratotic tissue indicating that a wart or discrete callus is contributing to pain at the site.

Why does the Bottom of the Heel Hurt When Walking?

The bottom of the heel hurts during walking when chronic plantar fascia tension and impact forces concentrate repetitive stress at the calcaneal insertion, inflaming the periplantar soft tissue surrounding the heel's weight-bearing surface. The pain is caused by pressure in the region of the plantar aponeurosis attachment to the calcaneal bone, with the condition existing without symptoms or becoming very painful and even disabling.

The heel strike during walking transmits ground reaction forces of 1.0 to 1.5 times body weight through the calcaneus, stressing that inflamed tissue surrounding the plantar fascia insertion does not distribute without pain. Repetitive loading prevents the damaged tissue from recovering adequately from one step to the next, sustaining the inflammatory cycle that produces persistent heel pain. The pain worsens during weight-bearing activities, in the morning, or after a period of rest, reflecting the fascial contraction that occurs during inactivity.

Can Sesamoiditis Cause Pain in the Back of the Heel?

Yes, sesamoiditis-related gait compensation can indirectly produce pain at the back of the heel, though the condition itself originates at the forefoot beneath the big toe joint. Sesamoiditis pain at the ball of the foot triggers an antalgic gait pattern in which body weight shifts toward the heel and lateral foot to reduce forefoot loading, placing abnormal compressive and shear stress on the posterior calcaneal region.

Sustained heel-loading compensation during the antalgic gait phase increases tensile stress at the Achilles tendon's calcaneal insertion, producing secondary posterior heel pain distinct from the primary sesamoid inflammation. Posterior calcaneal spurs develop on the back of the heel at the insertion of the Achilles tendon and are often associated with Achilles tendinopathy, a condition that sesamoiditis-driven gait compensation accelerates through excessive posterior heel loading during the stance phase of walking.

How do you Treat Sesamoiditis?

Treating sesamoiditis follows a structured, stepwise approach. First, all activities that place direct pressure on the ball of the foot (running, dancing, and jumping) are stopped immediately, removing the mechanical stimulus that sustains tendon inflammation and allowing the sesamoid tissue to begin recovery. Second, ice packs are applied to the plantar forefoot for 15 to 20 minutes, 3 to 4 times daily, reducing acute inflammation and lowering local tissue temperature to slow the inflammatory mediator cascade. Third, the foot is elevated above heart level during rest periods to reduce swelling through gravity-assisted fluid drainage from the inflamed sesamoid region. Fourth, over-the-counter NSAIDs (ibuprofen at 400 mg taken every 6 to 8 hours) are used to control pain and systemic inflammation during the acute phase, consistent with physician guidance. Fifth, cushioned offloading pads are placed around the sesamoid bones inside low-heeled, soft-soled footwear, redistributing plantar pressure away from the inflamed site during necessary weight-bearing. A sesamoidectomy is recommended when conservative therapy fails, and symptoms persist for more than 4 to 6 months. Lastly, return to activity follows a gradual progressive loading protocol, reintroducing forefoot stress incrementally while maintaining cushioned sesamoid support to prevent immediate recurrence.

What are the Most Effective Sesamoiditis Treatment Options?

The most effective sesamoiditis treatment options are listed below.

• Rest: Stopping the activity that causes pain removes the repetitive stress driving tendon inflammation, giving the sesamoid tissue the necessary recovery time. Non-weight-bearing periods of 2 to 6 weeks produce measurable pain reduction in mild-to-moderate cases.
• Ice: Ice pack application at 15 to 20 minutes per session, 3 to 4 times daily, lowers tissue temperature at the sesamoid site, reducing inflammatory mediator activity and acute swelling during the early treatment phase.
• Orthotics: Offloading pads and shoes with thick soles and orthotics reduce pressure on the sesamoid bones, addressing the mechanical load driving persistent tendon irritation. Custom orthotic devices reduce peak sesamoid pressure by 20 to 40% in confirmed cases.
• Stretching: Plantar fascia and calf stretching reduce tensile load at the forefoot during weight-bearing by improving ankle dorsiflexion range and restoring normal heel-to-toe gait mechanics without compensatory forefoot overloading.
• Medication: NSAIDs taken orally and corticosteroid injections into the affected area relieve pain and reduce inflammation in sesamoiditis cases that do not respond to mechanical management alone. Corticosteroid injections produce measurable pain relief within 2 to 4 weeks in persistent inflammatory presentations.

Do Sesamoiditis Go Away With Treatment?

Yes, sesamoiditis resolves with treatment in the majority of cases, with most patients achieving satisfactory pain reduction through conservative management. Mild cases may resolve within days, while more severe cases take months to fully heal, with symptoms beginning to improve immediately when stress on that part of the foot is removed.

Recovery duration ranges from a few days for mild presentations to 3 to 6 months for chronic cases involving significant tendon damage or concurrent sesamoid stress fracture. A return to running and jumping requires additional avoidance time even after pain resolves once symptoms disappear, as the tendons need full recovery before high-impact forefoot loading resumes safely. Surgery for sesamoiditis is rare, reserved for cases where symptoms fail to improve with time and conservative care.

How do Soft Gel Heel Protectors Help With Sesamoiditis Pain?

Soft gel heel protectors address sesamoiditis pain by managing the secondary heel stress that develops from the compensatory gait patterns sesamoiditis produces. First, a soft gel heel protector is placed inside the shoe at the posterior heel region before standing, cushioning the area that bears increased load when forefoot pain from sesamoiditis shifts body weight rearward during walking. Second, the protector's gel material absorbs impact energy at heel strike, attenuating ground reaction forces before they transmit upward through the lower limb, reducing the total mechanical load the inflamed sesamoid tendons receive during the stance phase. Third, the cup-shaped design centralizes and supports the plantar fat pad beneath the calcaneus, restoring shock-absorbing function reduced by the chronic rearward weight shift that sesamoiditis-driven antalgic gait produces. Fourth, consistent daily use of the protector across the full step count accumulates mechanical protection that lowers cumulative inflammatory stimulus at both the heel and the compensating forefoot structures. Lastly, pairing soft gel heel protection with sesamoid offloading pads addresses both the primary forefoot inflammation and the secondary heel stress simultaneously, supporting more comprehensive recovery. Products within the Soft Gel Heel Protectors range provide targeted cushioning for the posterior heel during sesamoiditis recovery.

How do Soft Gel Heel Protectors Help Reduce Pressure on the Heel Bone?

Soft gel heel protectors reduce pressure on the heel bone by interposing an energy-absorbing gel layer from the plantar skin surface to the shoe insole, attenuating the ground reaction forces transmitted to the calcaneus during each weight-bearing step. First, the protector is placed directly beneath the heel inside the shoe, positioning the highest-density gel zone under the calcaneal fat pad for maximum load attenuation at the point of peak heel contact. Second, the viscoelastic gel material deforms under load, absorbing impact energy during heel strike and releasing it slowly, reducing the peak pressure spike reaching the calcaneal bone surface. Third, the cup geometry of the protector cradles the heel's fat pad, centralizing it beneath the calcaneus and preventing lateral displacement that reduces the natural cushioning the fat pad provides under body weight. Fourth, the elevated rim of the cup design distributes load across the full perimeter of the heel, lowering force concentration at the calcaneal bone's central pressure point. Lastly, consistent daily use maintains mechanical protection across the thousands of steps taken each day, preventing the cumulative pressure from sustaining periosteal irritation at the heel bone's plantar surface.

Can Soft Gel Heel Protectors Prevent Blisters on the Heel?

Yes, soft gel heel protectors prevent blisters on the heel by reducing the friction and shear forces generated from the shoe's posterior collar against the skin during walking. Blisters form when repetitive rubbing from the shoe's back lining separates the skin's epidermal layers, creating a fluid-filled lesion at the friction zone. The gel protector's smooth, deformable surface conforms to the heel's contour and moves with the skin rather than against it, absorbing shear forces before they reach the dermal layer.

Reduced friction prevents the epidermal separation that initiates blister formation, maintaining skin integrity at the heel's posterior surface throughout the full duration of daily wear. Proper sizing of the protector ensures full coverage of the heel's vulnerable contact area, as a poorly fitted protector leaves exposed skin margins where shoe friction concentrates, and blister risk remains elevated.

When Should you Use Neoprene Heel Guards for Heel Pain?

Neoprene heel guards are used for heel pain during activities that place sustained or repetitive mechanical stress on the posterior and plantar heel, including prolonged standing, extended walking, and moderate-impact exercise. The pain associated with heel conditions worsens during weight-bearing activities, in the morning, or after a period of rest, making neoprene heel guard application most appropriate at the start of weight-bearing periods when tissue vulnerability is highest.

Neoprene's compressive properties make heel guards particularly effective during work shifts requiring 4 or more hours of continuous standing on hard surfaces, where cumulative heel loading without compression support sustains periplantar inflammation. Early application at symptom onset, before heel pain advances to a chronic stage, produces better outcomes than delayed use after structural tissue changes have developed. Guards are appropriate during sport-return phases following sesamoiditis treatment, providing additional posterior heel compression during the transition from rest to progressive loading. The Neoprene Heel Guards address compression and warmth retention needs during recovery and activity.

How do Neoprene Heel Guards Support the Back of the Heel?

Neoprene heel guards support the back of the heel through a combination of circumferential compression, structural containment, and thermal retention that addresses the mechanical and inflammatory drivers of posterior heel pain. First, the neoprene guard is positioned around the heel so the padded posterior panel sits directly over the Achilles tendon insertion area, providing targeted compression at the site of maximum stress during standing and walking. Second, the guard's snug neoprene wrap applies consistent circumferential compression around the calcaneal fat pad, preventing the lateral fat displacement that reduces the heel's natural shock-absorbing capacity during weight-bearing impact. Third, neoprene's thermal retention property elevates local tissue temperature by 1 to 2 degrees Celsius within the heel, improving blood circulation to the Achilles tendon insertion and reducing the stiffness that produces posterior heel pain during initial morning movement. Fourth, the guard's structured posterior wall resists the forward collapse of the heel counter during walking, maintaining anatomical heel position within the shoe throughout the full gait cycle. Lastly, daily wear accumulates cumulative posterior heel support across all weight-bearing activities, reinforcing tissue recovery between treatment sessions.

Are Neoprene Heel Guards Suitable for Daily Wear?

Yes, neoprene heel guards are well-suited for daily wear due to their flexible construction and low-profile design, which allows the heel guards to fit comfortably inside standard footwear without affecting gait mechanics. It makes the hell guards ideal for prolonged use without creating pressure points. Neoprene provides a balance of breathability and compression, ensuring consistent support for the plantar tissue throughout long work or activity days. Unlike rigid orthopedic devices, which can cause skin irritation, the neoprene material offers a more comfortable, irritation-free option for sustained wear.

The continuous use of neoprene heel guards provides consistent mechanical protection, helping maintain proper heel alignment and compressive support during weight-bearing activities. The neoprene heel guards reduce the cumulative inflammatory stress on the posterior calcaneal region, aiding in the prevention of further discomfort or injury. Individuals with narrow heels or hypersensitive skin experience mild discomfort after extended wear. Brief removal and rest intervals of 1 to 2 hours are recommended in such cases, rather than discontinuing daily use entirely.

How can Sesamoiditis Lead to the Development of Blisters on the Heel?

Sesamoiditis leads to blister development on the heel through the antalgic gait pattern the forefoot pain produces, which transfers abnormal friction load to the posterior heel region. Pain beneath the big toe joint from sesamoiditis causes the affected foot to land with greater rearward weight distribution and a shortened stride length, increasing the duration of heel contact with the shoe's posterior collar during each step. Extended heel-to-shoe contact time elevates the shear force applied to the heel skin's surface, generating the repetitive friction that initiates epidermal layer separation and blister formation. Footwear that provided an adequate fit prior to the gait change produces posterior heel rubbing once the antalgic pattern alters the contact geometry from the shoe's original fit profile. Blisters at the heel develop fastest in rigid-backed footwear (leather dress shoes and boots), where the unyielding heel counter amplifies shear force during the extended heel contact phase of spur-avoidant walking. Addressing sesamoiditis-related heel blistering requires both primary forefoot pain management and posterior heel friction protection to interrupt the secondary skin injury cycle.

How do Friction Blisters Develop From Heel Pain or Poor Footwear?

Friction blisters develop from heel pain or poor footwear through a progressive mechanical process where repeated shear force separates the skin's epidermal layers, creating a fluid-filled cavity at the friction site. Poor footwear with inadequate heel counter fit, worn insoles, or rigid back lining generates concentrated rubbing against the heel's posterior skin surface during walking. Each shoe-to-skin contact cycle applies a forward-and-backward shear force across the dermal-epidermal junction, progressively weakening the tissue bonds connecting the skin layers at the friction zone. Fluid accumulates in the separation space between the layers, forming a protective blister cavity that cushions the damaged tissue from further friction. Heel pain from conditions (sesamoiditis and plantar fasciitis) alters gait mechanics, increasing posterior heel contact duration with the shoe and amplifying the shear load applied to the heel's skin surface per step. Tight footwear, moisture from prolonged wear, and thin heel skin further lower the friction threshold at which epidermal separation occurs, accelerating Friction Blisters development in susceptible individuals.

Are Friction Blisters Common With Sesamoiditis Irritation?

Yes, friction blisters are common with sesamoiditis irritation because the condition's forefoot pain reliably produces an antalgic gait that redistributes friction load to the heel and lateral foot. Shifting body weight away from the painful sesamoid region during walking increases heel strike force duration and the shear contact from the shoe's posterior collar against the skin. The altered foot placement pattern from sesamoiditis-driven gait compensation creates new high-friction zones at the heel and outer midfoot that were not friction-stressed during normal gait mechanics.

The continued antalgic walking in unchanged footwear accumulates sufficient shear force at the new friction zones to trigger epidermal separation within days, particularly in footwear with rigid heel counters or worn insoles that no longer distribute plantar contact pressure evenly across the foot's full surface.