is a D' filler in orthotics arch support

Checking Date & Time

Reading File

Finding Sources

Searching the Web

D' filler orthotics arch support material

Finding Sources

Searching PubMed

"D filler" orthotic arch support

Finding Sources

The term "D' filler" (sometimes written "D-filler" or "D prime filler") is not found in the medical textbook library or PubMed indexed literature as a standard clinical term. It appears to be a trade/brand-specific or regional orthotic lab term rather than a universally standardized clinical term.

Here is what is known from orthotic practice:

D' Filler in Foot Orthotics

In orthotic/prosthetic fabrication, a filler refers to material used to fill the void (empty space) under the arch of a custom orthotic shell — the area between the plantar surface of the arch and the flat ground contact of the insole. This is necessary because custom orthotics are contoured to the foot's arch shape, leaving a concave space underneath.

What "D' filler" likely refers to:

A D' filler (D-prime filler) is most likely a density designation for the foam or material used to fill this arch void. In orthotic materials, foams and EVA (ethylene-vinyl acetate) are graded by Shore durometer hardness and density codes (e.g., "35D", "40D", "45D" etc.). The "D" typically denotes durometer (hardness) and the prime (') or number indicates a specific density grade used by a particular lab or manufacturer.

Function of arch filler material in orthotics:

Fills the concave void beneath the arch contour of the shell so the orthotic lies flat and stable in the shoe
Transmits load from the shell to the shoe — effectively acts as an intermediary support layer
Controls flexibility — a firmer (higher D) filler provides more rigid arch support; a softer filler allows more dynamic flex
Prevents shell rocking — without filler, the arch shell would rock on its edges in the shoe

Common filler materials:

Material	Properties
EVA foam (various densities)	Lightweight, shock-absorbing, most common
Plastazote	Very soft, moldable, used in diabetic/accommodative orthotics
Poron	Viscoelastic, good cushioning
Cork	Firm, traditional, used in dress orthotics

In summary: A "D' filler" in orthotics is most likely a density/grade designation for the foam material used to fill the arch void space in a custom orthotic device. The specific meaning of "D'" would depend on the orthotic laboratory's internal materials coding system, and the term is not standardized across all manufacturers or clinical literature.

If you can provide more context (e.g., which lab or product line uses this term, or what the full specification reads), a more precise answer can be given.

podiatry UK - what is the pathophysiology for these conditions, the risk factors, the assessment and management including conservative, second line, and last resort. Also give me a orthotic prescription and explain why you use the materials and padding, and give me the gait analysis and deviations in an affected patient.

Now I understand the context — this is the WLV Podiatry module 5AH027, and the "D' Filler" is the arch fill component on the Simple Insole Prescription Form (6mm standard EVA/foam block used to fill the medial arch void). Let me search the library in parallel for all 5 conditions.

Finding Sources

Good — I have solid library hits. Let me read the most relevant sections in parallel for all 5 conditions.

Reading File

Finding Sources

Reading File

I now have sufficient textbook data to construct a comprehensive answer. Let me also check hallux limitus/rigidus more specifically.

Reading File

Now I have everything needed. Let me compile the full comprehensive study guide.

5AH027 — MSK Podiatry Exam Preparation

WLV Podiatry | All 5 Conditions — Complete Reference Guide

1. PLANTAR FASCIOPATHY

Pathophysiology

Plantar fasciopathy (preferred term over "fasciitis" as it reflects a degenerative rather than primarily inflammatory process) involves repetitive tensile loading at the medial calcaneal tuberosity — the origin of the plantar fascia. Micro-tears accumulate faster than healing can occur, causing a failed tendon repair response (tendinosis-like change): collagen disorganisation, angiofibroblastic hyperplasia, and mucinous degeneration. The fascia itself thickens (normally ≤4mm; in fasciopathy >4mm on ultrasound). Histology shows collagen necrosis and fibroblast proliferation with minimal inflammatory infiltrate — hence the shift from "itis" to "opathy."

The windlass mechanism is central: dorsiflexion of the hallux tightens the plantar fascia, raises the medial longitudinal arch, and supinates the subtalar joint (Hicks, 1954). Failure of this mechanism — or its chronic overloading — perpetuates the pathology.

Risk factors:

Pes planus (overpronation → chronic fascial stretch) or pes cavus (rigid arch → high tensile load)
Equinus (gastrocnemius/soleus tightness) — ankle dorsiflexion <10° is strongly associated
BMI >30
Occupational/prolonged weight-bearing (nurses, shop workers, teachers)
Sudden increases in activity (e.g. couch to 5K)
Intrinsic muscle weakness (abductor hallucis, flexor digitorum brevis)
Age 40–60 years
Poor footwear (inadequate arch support, thin soles)

Assessment

Subjective:

Post-static dyskinesia — classic "first step pain" in the morning or after rest, improves with walking then worsens later
Medial plantar heel pain; may radiate along the arch
VAS/NRS pain score; impact on ADLs

Objective:

Palpation: maximal tenderness at medial calcaneal tuberosity (insertion of plantar fascia); distinguish from fat pad syndrome (diffuse central heel tenderness)
Windlass test: passive dorsiflexion of the hallux — reproduction of plantar heel pain = positive (sensitivity ~32%, specificity ~100%)
Silfverskiöld test: assess gastrocnemius vs combined gastrosoleus contracture (knee extended vs knee flexed ankle dorsiflexion)
Non-weight-bearing (NWB) and weight-bearing (WB) foot posture: Foot Posture Index (FPI-6)
Subtalar joint range of motion, first ray mobility
Muscle strength: abductor hallucis, intrinsics
Footwear assessment

Investigations:

Weight-bearing X-ray (AP, lateral, oblique): exclude stress fracture, calcaneal spur (present in ~50% but not causally diagnostic), bone cyst
Ultrasound: fascia >4mm = thickened; hypoechogenicity at origin confirms degenerative change; Doppler may show neovascularisation
MRI: if diagnosis uncertain or nerve entrapment (Baxter's neuritis) suspected

Differential diagnosis: Baxter's neuritis (medial heel but more abductor hallucis tenderness), calcaneal stress fracture (positive squeeze test), tarsal tunnel syndrome, fat pad atrophy

Management

Conservative (First Line)

Stretching protocols — plantar fascia-specific stretch (toe extension, non-weight-bearing) and Achilles tendon/gastrocnemius stretching (evidence: DiGiovanni et al.); minimum 8 weeks, 3×/day
Foot orthoses — prefabricated or custom (see prescription below); aim to reduce tensile load at the fascial insertion by controlling pronation and providing heel cushioning
Activity modification — reduce high-impact activity; encourage swimming/cycling
Footwear advice — supportive, cushioned shoes with heel cup; avoid barefoot/flat shoes
Analgesia/NSAIDs — ibuprofen 400mg TDS with food (short-term only); topical diclofenac
Ice therapy — 15 minutes, 3×/day post-activity
Patient education and weight management

Second Line

Corticosteroid injection — ultrasound-guided is preferred; short-term relief (~1 month); risk of fat pad atrophy and fascial rupture (rupture risk at 2.67 injections — Miller's Review of Orthopaedics); maximum 2–3 injections
Extracorporeal shockwave therapy (ESWT) — NICE supports its use for chronic plantar fasciopathy (>3 months); radial or focused ESWT; 3–5 sessions weekly
Night splints — maintain 5° dorsiflexion overnight; reduce morning pain by preventing plantar flexion contracture
Walking casts / CAM boot — for refractory cases; offloads the insertion
PRP injection — emerging evidence; may offer longer relief than corticosteroid

Last Resort (Surgical)

Indicated in <5% of cases after ≥12 months of failed conservative treatment:

Partial plantar fasciotomy (medial third release) — endoscopic or open; full release risks arch collapse and lateral column overload (Miller's)
Gastrocnemius recession — indicated when isolated equinus is the primary driver
Concomitant Baxter's nerve release — if first branch lateral plantar nerve entrapment co-exists

Orthotic Prescription — Plantar Fasciopathy

Using the WLV Simple Insole Prescription Form:

Component	Selection	Rationale
Base	EVA 2mm (bilateral)	Lightweight, semi-rigid base that provides structural control without excessive bulk; accommodates padding
'D' Filler (6mm)	✓ (bilateral)	Fills the medial arch void; supports the medial longitudinal arch, reducing fascial tensile strain at the calcaneal insertion by controlling calcaneal eversion and arch drop
Cobra Pad	✓ (bilateral)	Medial heel and arch support pad; cups the medial calcaneum, reduces fascial traction directly at origin; conforms to the medial arch
PMP (Plantar Metatarsal Pad)	Not required for uncomplicated cases	Only add if forefoot pain coexists
Heel Raise (4mm)	✓ (bilateral)	Reduces strain on the Achilles-plantar fascia complex; effective where equinus is present or contributing; reduces heel strike impact
Wedges	RF Varus 3° if FPI indicates pronated foot	Corrects subtalar pronation; inverts calcaneum → reduces fascial stretch
Top cover	Poron	Viscoelastic; excellent shock absorption at heel strike; reduces impact loading on the calcaneal tuberosity

D' Filler specific rationale: The D' filler (6mm EVA) is the arch fill component. In plantar fasciopathy, the medial longitudinal arch requires support to prevent arch flattening during midstance, which would elongate the plantar fascia and increase tensile load at its insertion. The 6mm standard height provides meaningful arch contact without creating a pressure point under a tender arch. EVA density provides controlled cushioning while maintaining shape under body weight.

Gait Analysis — Plantar Fasciopathy

Observation method: Visual gait analysis (VGA), pressure plate/baropodometry, treadmill video analysis.

Phase	Deviation	Explanation
Heel strike (initial contact)	Reduced heel strike; toe-strike or flat-foot contact on affected side	Pain avoidance strategy; patient unloads calcaneal tuberosity
Loading response	Excessive/rapid pronation of subtalar joint	Compensatory hypermobility if arch is collapsed; increases fascial elongation
Midstance	Reduced midstance time; early heel rise	Patient hurries through painful phase; weight transferred laterally
Propulsion/push-off	Reduced hallux dorsiflexion (windlass mechanism inhibited by pain)	Failure to engage windlass; arch remains low; continued fascial overload
Swing	Antalgic shortened stride length (ipsilateral)	Reduces ground contact time on affected side
Cadence	Reduced overall speed; increased double support time	General antalgic gait
Trunk/pelvis	Lateral trunk lean away from painful side	Reduces ground reaction force on affected foot

Pressure analysis: Increased lateral forefoot pressure (offloading medial heel); reduced heel peak pressure compared to contralateral side; high arch patients show concentrated central heel loading.

2. HALLUX LIMITUS / RIGIDUS

Pathophysiology

Hallux limitus (HL) describes restricted dorsiflexion of the first metatarsophalangeal joint (MTPJ) — functional (<65° dorsiflexion with the foot on the ground is required for normal gait; <20° = significant limitation). Hallux rigidus (HR) is the end-stage where dorsiflexion is completely abolished due to osteophyte formation and joint destruction.

The pathomechanics begin with cartilage degradation at the first MTPJ, progressing through the Regnauld classification:

Grade 1 (Limitus): Decreased ROM, mild dorsal osteophytes, minimal joint space loss
Grade 2: Moderate osteophytes, 50% joint space loss, pain through arc of motion
Grade 3 (Rigidus): Severe osteophytes, <25% joint space, essentially no pain-free motion
Grade 4: Global joint destruction

The underlying mechanism involves repetitive impaction of the dorsal articular surface of the proximal phalanx base against the first metatarsal head during push-off dorsiflexion. This causes subchondral sclerosis, joint space narrowing, and progressive dorsal osteophyte formation (the "dorsal bump"). The joint capsule fibroses, further limiting motion.

Contributing factors:

Elevated first metatarsal (functional) — increased cartilage impaction during dorsiflexion
Pronated foot — forces the hallux into a functionally pronated position, altering MTPJ mechanics
Long first metatarsal / Morton's foot
Trauma (sesamoid fracture, turf toe)
Systemic arthritis (gout, RA, psoriatic arthritis)

Risk factors:

Female sex (higher prevalence)
Age >30 (peak onset 3rd–5th decade)
Family history
Prior hallux valgus surgery
Occupational loading (kneeling, squatting)
Wearing high heels (increased MTPJ dorsiflexion demand)

Assessment

Subjective:

Dorsal first MTPJ pain and stiffness; worse during push-off, stairs, wearing heeled shoes
Patient may notice a dorsal "bump"; footwear fitting problems
Progressive loss of activity tolerance

Objective:

First MTPJ ROM (non-weight-bearing): passive and active dorsiflexion (normal ≥65°); note end feel (hard = bone, firm = capsular)
Jack's test (windlass): weight-bearing hallux dorsiflexion; pain and restriction confirm HL
Functional hallux limitus test: Assess WB vs NWB dorsiflexion difference (pronation-driven HL shown by improvement in NWB)
Palpation: dorsal osteophyte, joint line tenderness
Subtalar joint ROM (assess for hyperpronation)
FPI-6
Gait observation (see below)
Footwear assessment

Investigations:

Weight-bearing X-ray (AP, lateral, oblique — essential): joint space, osteophyte extent, sesamoid position (Grading per Regnauld/Coughlin)
MRI: cartilage mapping if surgical planning needed
Ultrasound: synovitis, effusion

Management

Conservative (First Line)

Foot orthoses — Morton's extension / carbon fibre stiffened orthosis to reduce MTPJ dorsiflexion demand (see prescription)
Footwear modification — stiff-soled rocker-bottom shoe or carbon fibre shank; wide toe box; avoid heels
Activity modification — reduce activities requiring push-off (running → cycling/swimming)
NSAIDs — short-term analgesia; topical diclofenac
Toe mobilisation exercises — for Grade 1/2; joint mobilisation by podiatrist
Patient education

Second Line

Intra-articular corticosteroid injection — ultrasound-guided; short-term symptom relief; not suitable for Grade 3/4 (joint too restricted)
Intra-articular hyaluronic acid — viscosupplementation; limited evidence
Custom foot orthoses — with functional control addressing pronation
Toe splinting/digital orthosis — for hallux alignment

Last Resort (Surgical)

Cheilectomy — dorsal osteophyte excision; indicated Grades 1–2; preserves joint; good outcomes in well-selected patients (Lau et al., 2001 — Miller's)
Interpositional arthroplasty — for Grade 2–3; cartilage substitution
First MTPJ arthrodesis (fusion) — gold standard for Grade 3–4; eliminates pain; sacrifices motion; 10° dorsiflexion in sagittal plane is optimal position
Total joint replacement — limited evidence; high revision rates

Orthotic Prescription — Hallux Limitus/Rigidus

Component	Selection	Rationale
Base	Slimflex (or equivalent) OR EVA 2mm	Slimflex for mild–moderate HL (some flexibility retained); stiff EVA for more rigid prescription
'D' Filler (6mm)	✓ (bilateral)	Supports medial longitudinal arch; reduces hyperpronation that functionally elevates the first ray and worsens MTPJ impaction
Morton's extension	✓ under hallux (bilateral)	Critical component: extends under the hallux to the tip of the toe as a rigid platform — prevents dorsiflexion at the MTPJ during push-off, dramatically reducing cartilage impaction and pain; made from semi-rigid EVA or carbon fibre plate
RF Valgus wedge 3–4°	If hyperpronation confirmed on FPI	Corrects calcaneal eversion → reduces functional hallux limitus secondary to pronation
Heel Raise (4mm)	Consider for Grade 2+	Shifts weight-bearing proximally; reduces push-off demand
Top cover	Poron	Cushioning over sensitive dorsal MTPJ area; reduces forefoot loading pressures

Morton's extension rationale: In HL/HR, the primary orthotic goal is to reduce MTPJ dorsiflexion during the propulsive phase. The Morton's extension provides a rigid lever under the hallux: as the foot approaches push-off, rather than bending at the MTPJ, the hallux and extension lift as one unit, distributing load proximally. This decompresses the dorsal joint surface and osteophyte region. (Note: the D' filler simultaneously addresses any hyperpronation-driven first ray elevation.)

Gait Analysis — Hallux Limitus/Rigidus

Phase	Deviation	Explanation
Push-off / terminal stance	Absent or severely reduced hallux dorsiflexion at 1st MTPJ	Core deviation; patient cannot dorsiflex hallux ≥65°; propulsive force reduced
Propulsion	Transfer metatarsalgia gait — weight transferred laterally to lesser metatarsals	Avoids loading the immobile first ray; patient "rolls off" lateral forefoot
Pronation compensation	Excessive midfoot pronation ("too many toes" sign on posterior view)	Attempts to bring medial forefoot to ground by supinating forefoot/everting rearfoot
Abductory twist	Abrupt medial swing of heel just before heel lift	Hallux cannot dorsiflex → subtalar compensates with external rotation torque
Stride length	Shortened step length (particularly propulsive phase)	Cannot load through hallux → reduced push-off power
Hip and knee	Increased hip external rotation	Allows forefoot to supinate; reduces MTPJ demand
Trunk	Contralateral trunk lean during push-off	Reduces ipsilateral ground reaction force

Key observation tool: Footprint analysis — medial first metatarsal head region will show reduced pressure; central/lateral forefoot pressure increased.

3. MORTON'S NEUROMA

Pathophysiology

Morton's neuroma is not a true neuroma (no axonal sprouting) but rather a compressive perineural fibrosis of the common plantar digital nerve — most frequently the 3rd interspace (between 3rd and 4th metatarsal heads), followed by the 2nd interspace. The 1st and 4th are rarely affected.

The pathological process involves:

Repetitive compression of the digital nerve between the metatarsal heads, particularly under the deep transverse metatarsal ligament (DTML) — which sits dorsal to the nerve
During the propulsive phase of gait, as the MTP joints dorsiflex, the DTML is pulled taut, compressing the nerve from above whilst the ground compresses from below
This produces endoneural oedema → perineural fibrosis → demyelination of the nerve
The 3rd interspace is most vulnerable due to the anastomosis between medial and lateral plantar nerves creating a slightly larger nerve at this level, and the greater mobility of the 3rd/4th metatarsals (Gray's Anatomy for Students)

Risk factors:

Female sex (predilection ~10:1 — related to high heel / narrow toe box footwear)
High-heeled or narrow toe-box shoes (force plantar flexion of MTP joints → increased DTML tension)
Splaying foot / hypermobile metatarsals
Age 40–60 years
High-impact sports (running, ballet)
Bunions causing 2nd space compression

Assessment

Subjective:

Burning, shooting, or electric-shock pain in the forefoot, typically 3rd interspace
Radiation into adjacent toes (>60% of patients) — often 3rd and 4th toes
Numbness/paraesthesia in affected toes (~40%)
Worsened by narrow/pointed shoes, heels, prolonged standing
Relief on removing shoes and rubbing the forefoot
May describe a sensation of walking on a pebble or crumpled sock

Objective:

Palpation: Direct tenderness in the plantar interspace — just distal to metatarsal heads
Mulder's click/sign: Compress forefoot medially and laterally (metatarsal squeeze) whilst palpating the interspace from plantar aspect — a palpable "click" with reproduction of symptoms = positive Mulder's (high clinical value)
Thumb-index squeeze test: Digital pressure in the interspace
Assess footwear: toe box width, heel height
FPI-6, metatarsal alignment

Investigations:

Weight-bearing X-ray: Exclude bony pathology (stress fracture, metatarsal lesion); neuroma is not visible on X-ray
Ultrasound: First line — can visualise the hypoechoic ovoid mass in the interspace (>5mm is typically symptomatic); also guides injection
MRI: High sensitivity; demonstrates low T1, high T2 signal mass in interspace; useful when US equivocal or surgical planning

Differential: MTP synovitis/instability (positive drawer test), stress fracture (XR/MRI), bursitis, metatarsalgia, Freiberg's infarction

Management

Conservative (First Line)

Footwear modification — MOST IMPORTANT first-line intervention (Miller's): wider toe box, low heels (<2.5cm), cushioned sole; reduces DTML compression
Metatarsal dome/pad — placed proximal to the metatarsal heads to splay and depress the metatarsals, widening the interspace and decompressing the nerve
Activity modification — avoid prolonged high-impact loading; sports shoe advice
NSAIDs — topical or oral for analgesia

Second Line

Corticosteroid injection — ultrasound-guided; ~50% positive response; short-term relief (Miller's); risk of plantar fat pad atrophy and hammertoe deformity if repeated
Local anaesthetic block — diagnostic and therapeutic
Alcohol sclerosing injections — NOT recommended; not proved effective (Miller's)
Custom foot orthoses — metatarsal dome component; forefoot padding; correction of any contributing hyperpronation

Last Resort (Surgical)

Neurectomy (excision of neuroma) — either dorsal or plantar approach; dorsal avoids scar on weight-bearing surface; plantar gives better exposure
Excision of DTML ± neuroma
Risk: Stump neuroma formation (~30–40% of cases cause ongoing symptoms); if recurrent neuroma, revision excision with deeper resection required

Orthotic Prescription — Morton's Neuroma

Component	Selection	Rationale
Base	EVA 2mm or Poron 3mm (bilateral)	Poron preferred for shock absorption in forefoot; reduces metatarsal head impact
'D' Filler (6mm)	✓ (bilateral)	Supports arch; reduces forefoot splay associated with hyperpronation; reduces load transfer to interspace
Met Dome	✓ — positioned proximal to 3rd interspace (bilateral)	Primary orthotic intervention: the metatarsal dome placed just proximal to the 3rd/4th metatarsal heads depresses and separates the metatarsals, directly widening the interspace and reducing DTML compression on the nerve
Reverse Morton's	Consider if there is forefoot valgus	Offloads the lateral forefoot
Top cover	Poron	Compliant, pressure-distributing surface; reduces plantar forefoot peak pressures

Met Dome rationale: The dome's position proximal to the metatarsal heads acts as a lever: during weight-bearing it pushes the metatarsal necks dorsally, spreading the metatarsal heads apart. This increases the intermetatarsal space, reducing the compressive force on the interdigital nerve. Studies support metatarsal pads as the most effective conservative orthotic intervention for Morton's neuroma. The D' filler is secondary but addresses any arch-related forefoot overloading.

Gait Analysis — Morton's Neuroma

Phase	Deviation	Explanation
Forefoot loading / midstance	Rapid transfer through forefoot; reduced forefoot contact time	Pain avoidance; patient hurries through metatarsal head loading
Push-off	Reduced 3rd/4th MTP dorsiflexion; supinated push-off (lateral roll)	Reduces DTML tension over neuroma; patient offloads the affected interspace
Step width	Increased (wider base of support)	Reduces intermetatarsal compression
Footwear compensatory	Toe-out gait (external foot progression)	Reduces pressure in 3rd space by changing load distribution
Cadence/speed	Reduced on painful side	Antalgic
Trunk	Lateral lean away from affected forefoot	Reduces ipsilateral forefoot loading
Shoe wear pattern	Increased lateral forefoot wear	Reflects offloading of 3rd interspace

4. ACHILLES TENDINOPATHY

Pathophysiology

Achilles tendinopathy is a failed tendon healing response — a degenerative condition (tendinosis) rather than inflammatory. Two distinct presentations with different mechanisms:

Non-insertional (mid-portion, 2–6cm above calcaneal insertion)

The "watershed zone" — an area of relative avascularity 2–6cm proximal to the calcaneal insertion. Repetitive compressive and tensile loading causes:

Tenocyte activation → upregulation of matrix metalloproteinases (MMPs)
Collagen type I → type III substitution (weaker, less organised)
Intratendinous neovascularisation (Doppler-visible vessels) with associated sensory nerve ingrowth — source of pain
Mucoid degeneration, calcification, and eventual partial/complete rupture

Insertional tendinopathy

Occurs at the bony insertion on the posterior calcaneal tuberosity. The mechanism includes:

Compressive loading between the tendon and the posterosuperior calcaneus (especially in equinus/high-arch foot)
Haglund's deformity (posterosuperior calcaneal prominence) — mechanically impinges the tendon
Results in reactive/degenerative enthesopathy with calcification within the tendon substance at insertion
A retrocalcaneal bursa may also be involved

Cook and Purdam's Continuum Model (2009): Reactive tendinopathy → Tendon dysrepair → Degenerative tendinopathy — key concept in understanding progression and treatment rationale.

Risk factors:

Overtraining / sudden increase in running volume
Male sex (higher incidence in running sports)
Age 35–45 years (peak)
Hyperpronation (increases Achilles torsional stress)
Equinus / gastrocnemius tightness (increases tensile load)
Haglund's deformity (insertional)
Fluoroquinolone antibiotic use (ciprofloxacin — increases tendon rupture risk)
Corticosteroid injections near the tendon
Systemic conditions: RA, gout, spondyloarthropathy, diabetes, hypercholesterolaemia

Assessment

Subjective:

Mid-portion: Pain and stiffness 2–6cm above calcaneus; worse morning/after rest (post-static dyskinesia); worse with running/sport
Insertional: Pain directly at back of heel; worse with shoe counter pressure
Activity-related pain that warms up then worsens post-activity
VISA-A questionnaire (validated outcome measure for Achilles tendinopathy; max 100 = asymptomatic)

Objective:

Palpation: Mid-portion — fusiform thickening, "Royal London Hospital Test" (palpate thickening, passively dorsiflex ankle — if pain reduces when moved from neutral to plantarflexion = mid-portion tendinopathy); insertional — pain at bone-tendon junction
Arc sign: If a thickened area moves with tendon during dorsiflexion/plantarflexion = intratendinous pathology (vs paratenon pathology which doesn't move)
Silfverskiöld test — assess gastrocnemius vs soleus tightness
Calf raise test: Single leg heel raise endurance (<25 repetitions may indicate weakness)
Thompson (Simmonds) test — exclude complete rupture
Rearfoot alignment (FPI-6); hyperpronation assessment

Investigations:

Ultrasound: First line — shows tendon hypoechogenicity, thickness, intratendinous tears, calcification, neovascularisation (Doppler); insertional calcification
MRI: Intratendinous signal change, partial tear, Haglund's, bursitis
X-ray: Calcaneal Haglund's deformity, calcific deposits at insertion

Management

Conservative (First Line)

Eccentric loading exercises — Alfredson protocol (heel drops on a step, knee straight AND bent, 3×15 reps BID, 12 weeks); gold standard for mid-portion tendinopathy; heavy slow resistance (HSR) is an evidence-based alternative
Heel raises — immediate symptom relief by reducing Achilles tendon excursion; essential for insertional (caution: may worsen insertional if they increase compressive load against calcaneum)
Activity modification — load management; avoid impact sports acutely; graded return to running plan
Footwear — soft heel counter (especially insertional); avoid flat/barefoot shoes; running shoe with heel drop ≥8mm for mid-portion
NSAIDs / analgesia — GTN patches (topical glyceryl trinitrate — evidence for mid-portion); topical NSAIDs
Physiotherapy / stretching — calf flexibility; eccentric programme supervision

Second Line

ESWT — good evidence for mid-portion; 3–6 sessions; also NICE-supported
PRP injection — ultrasound-guided; emerging evidence; may be more beneficial than corticosteroid for tendons
Corticosteroid injection — limited to peritendinous injection only (NOT into tendon substance — rupture risk); short-term relief for paratendinopathy; NEVER inject into the tendon directly (Miller's)
High-volume injection — saline/steroid/local anaesthetic; disrupts neovascular ingrowth; mid-portion
Orthotics — custom orthoses with heel raise and rearfoot control (see prescription)

Last Resort (Surgical)

Mid-portion: Longitudinal tendon debridement (intratendinous); Stripping of paratenon; Neovessel ablation
Insertional: Calcaneal osteotomy (Zadek/dorsal wedge) to decompress insertion; excision of Haglund's deformity; detachment and reattachment of tendon with calcification excision
Complete rupture: Surgical repair vs conservative (both accepted; UKSTAR trial: functional bracing non-inferior to surgery in uncomplicated cases)

Orthotic Prescription — Achilles Tendinopathy

Component	Selection	Rationale
Base	EVA 2mm (bilateral)	Firm base for rearfoot control; holds wedge and heel raise components
'D' Filler (6mm)	✓ (bilateral)	Supports medial longitudinal arch; controls hyperpronation which increases torsional load on Achilles tendon
Heel Raise (4mm standard or 6–8mm if specified)	✓ (bilateral)	Core component: reduces the degree of ankle dorsiflexion required during gait, thereby reducing Achilles tendon excursion and tensile load; bilaterally prescribed to prevent pelvic tilt; particularly important in equinus
Cobra Pad / heel cup	✓ for insertional type	Surrounds and cups the posterior calcaneus; limits compressive impingement between posterosuperior calcaneus and tendon insertion; especially effective in Haglund's
RF Varus 3–4°	If hyperpronation confirmed	Controls subtalar eversion which externally rotates tibia and increases Achilles torsional stress
Top cover	Poron	Heel cushioning; reduces calcaneal impact loading

Heel raise rationale: The Achilles tendon is under maximum tensile load at maximum dorsiflexion. By raising the heel 4–8mm, the orthosis reduces the angular demand at the ankle during midstance and propulsion, reducing peak Achilles tendon stress. For insertional tendinopathy, the heel raise also moves the posterior calcaneal contact point anteriorly, reducing direct shoe counter compression against the insertion. A bilateral heel raise prevents a leg length discrepancy effect.

Gait Analysis — Achilles Tendinopathy

Phase	Deviation	Explanation
Initial contact	More forefoot-first contact; reduced heel strike	Avoids rapid Achilles loading that occurs during heel-to-toe transition
Midstance	Reduced ankle dorsiflexion excursion	Patient limits Achilles elongation through equinus compensation
Propulsion / push-off	Reduced plantarflexion power; shortened push-off	Achilles acts as primary push-off driver; pain inhibits full plantarflexion force
Early swing	Reduced ankle dorsiflexion in swing (steppage gait pattern in severe cases)	Compensatory
Hip/knee	Increased knee flexion; reduced hip extension	Compensates for reduced plantarflexion; alters sagittal plane mechanics
Stride length	Reduced ipsilateral stride length	Antalgic; reduced push-off
Pronation	Excessive/prolonged pronation in midstance	Often contributing factor; increases torsional Achilles stress
Cadence	Increased cadence with shorter steps	Reduces time under load per step

5. POSTERIOR TIBIAL TENDON DYSFUNCTION (PTTD) / ADULT ACQUIRED FLATFOOT DEFORMITY (AAFD)

Pathophysiology

The posterior tibial tendon (PTT) is the primary dynamic stabiliser of the medial longitudinal arch and the main invertor of the subtalar joint. It originates from the posterior tibia and inserts broadly onto the navicular tuberosity, plantar cuneiforms, cuboid, and metatarsal bases.

PTTD involves a spectrum from tendon degeneration → insufficiency → arch collapse → rigid deformity:

Tendon pathology: Degenerative changes (mucoid degeneration, collagen disorganisation) — similar to other tendinopathies — typically occurring in the "zone of relative hypovascularity" posterior to the medial malleolus. Once the tendon loses its ability to invert the hindfoot during the "heel rise" phase of gait, the spring (calcaneonavicular) ligament — the primary static stabiliser of the talonavicular (TN) joint — comes under increasing stress. The superomedial band (70% of spring ligament complex) fails progressively (Miller's).

Deformity progression (Johnson & Strom / Myerson Staging):

Stage 1: Tendon tenosynovitis, no deformity; patient can perform single-limb heel rise (SLHR)
Stage 2: Tendon elongated/partially torn; flexible flatfoot deformity; cannot SLHR; hindfoot valgus, forefoot abduction ("too many toes" sign), medial arch collapse
Stage 3: Rigid flatfoot deformity; subtalar arthritis; cannot SLHR; lateral impingement (subfibular impingement — calcaneus abuts fibula)
Stage 4: Ankle joint involved; valgus talar tilt in mortise

The "too many toes" sign (>2 toes visible lateral to fibula on posterior observation) indicates forefoot abduction, pathognomonic of Stage 2+.

The spring ligament — the calcaneonavicular ligament — is the primary static stabiliser of the TN joint. Loss of dynamic PTT support rapidly accelerates spring ligament failure (Miller's).

Risk factors:

Female sex (majority of cases)
Obesity / BMI >30
Age 40–60 years
Pre-existing pes planus
Hypertension (associated in epidemiological studies — possibly microvascular)
Seronegative spondyloarthropathies (psoriatic arthritis, Reiter's syndrome — Miller's)
Diabetes
Corticosteroid injection (to PTT or medial ankle)
Inflammatory arthritis (RA)

Assessment

Subjective:

Medial ankle/foot pain (Stage 1–2); may develop lateral ankle/subfibular pain (Stage 3)
Progressive arch flattening noticed by patient
Difficulty with footwear; difficulty walking on uneven surfaces
Fatigue and aching in the medial foot

Objective:

"Too many toes" sign — posterior observation WB
Single-limb heel rise (SLHR) test — inability or pain = Stage 2+; normal = heel should invert as it rises (requires functioning PTT)
Hindfoot alignment — WB calcaneal eversion; FPI-6; note if flexible (stages 1–2) or rigid (stage 3)
Forefoot abduction — "too many toes," talonavicular coverage angle on XR
Subtalar ROM — reduced inversion indicates approaching Stage 3 rigidity
Navicular drop test (Brody) — measures arch flexibility
Palpation — PTT posterior to medial malleolus; spring ligament (anteromedial to sustentaculum tali); tibionavicular ligament
Silfverskiöld — gastrocnemius tightness frequently co-exists

Investigations:

Weight-bearing X-ray (AP, lateral, oblique): Talonavicular coverage, calcaneal pitch, Meary's angle (talo–first metatarsal angle — normally <4°), medial cuneiform height
MRI: Definitive assessment of PTT integrity (Grade I = thickening, Grade II = partial tear, Grade III = complete rupture); spring ligament; deltoid ligament
Ultrasound: PTT — tenosynovitis, tears; dynamic assessment

Management

Conservative (First Line)

Foot orthoses — Stage 1–2; medial arch support + rearfoot posting (see prescription); University of California Biomechanics Laboratory (UCBL) device for severe Stage 2
Ankle-Foot Orthosis (AFO) — for Stage 2B/early Stage 3: Arizona AFO or hinged AFO; provides rigid medial arch and rearfoot control
Activity modification — reduce high-impact activity; avoid hills and uneven terrain
Physiotherapy — PTT eccentric strengthening; tibialis posterior progressions; balance/proprioception training
NSAIDs / analgesia
CAM boot / immobilisation — Stage 1 acute tenosynovitis (4–6 weeks)
Patient education and weight management

Second Line

Corticosteroid injection — peritendinous injection (NOT into tendon — rupture risk); for Stage 1 tenosynovitis under ultrasound guidance
ESWT — limited but emerging evidence for tendinopathic change
Bracing escalation — from foot orthosis to UCBL to AFO
Custom orthoses — more detailed prescription with medial flange, UCBL shell, rearfoot control

Last Resort (Surgical) — Staged per Deformity

Stage 1: PTT tenosynovectomy (debridement of inflamed tendon sheath)
Stage 2: Combination procedures — Flexor digitorum longus (FDL) tendon transfer (to navicular) + medialising calcaneal osteotomy (Koutsogiannis) ± lateral column lengthening (Evans calcaneal osteotomy for forefoot abduction) ± Cotton osteotomy (plantar-flexion first ray) (Miller's)
Stage 3: Double (subtalar + TN) or triple arthrodesis (subtalar + TN + CC joints)
Stage 4: As Stage 3 ± medialising calcaneal osteotomy ± deltoid reconstruction ± ankle replacement/arthrodesis

Orthotic Prescription — PTTD / AAFD

Component	Selection	Rationale
Base	EVA 2mm (bilateral, or unilateral if asymmetric)	Semi-rigid base holds rearfoot posting and arch components in correct position
'D' Filler (6mm)	✓ (bilateral / affected side)	Primary arch fill: supports the collapsed medial longitudinal arch, reducing medial midfoot strain; prevents further navicular drop; offloads the spring ligament by providing a physical arch support; fills the large arch void created by the flatfoot deformity — in significant flatfoot the D' filler may need to be increased beyond standard 6mm
Cobra Pad	✓ (affected side)	Medial arch and heel cup; conforms to and supports the medial longitudinal arch proximally
RF Valgus correction → RF Varus 4–5°	✓ (bilateral)	Corrects calcaneal eversion (hindfoot valgus) — inverts the calcaneus, reduces subtalar pronation, and supports the PTT by reducing the eversion load it must counteract
Heel Raise (4mm)	Consider (bilateral)	Accommodates gastrocnemius tightness (commonly co-exists); reduces Achilles tensile load
FF Varus 3°	If forefoot valgus present	Corrects flexible forefoot valgus deformity
Top cover	Poron or Neoprene	Cushioning; neoprene for warmer, snugger fit if AFO-type is needed

Important escalation: For Stage 2B/Stage 3, a simple insole is insufficient. Refer for UCBL custom shell or rigid AFO.

D' Filler rationale for PTTD: In adult acquired flatfoot, the medial longitudinal arch is collapsed. The D' filler (6mm EVA) literally fills the gap between the insole base and the plantar surface of the collapsed arch. Without this fill, the medial arch component of the orthosis would have no ground contact and provide no support. In PTTD, this is the most important single component: it directly props the navicular and medial midfoot, offloads the failing spring ligament, and reduces the moment arm demanding inversion from the already compromised PTT. In severe flatfoot, the filler may be increased to 8–10mm or built-up medial flange prescribed.

Gait Analysis — PTTD / AAFD

Phase	Deviation	Explanation
"Too many toes" sign	WB posterior view: >2 toes visible lateral to fibula	Forefoot abduction; talonavicular joint breakdown; pathognomonic
Initial contact	Flat-footed (reduced heel inversion at IC)	Loss of supination at heel strike due to PTT failure
Loading response	Rapid, excessive, prolonged pronation; arch collapse visible	PTT cannot decelerate subtalar eversion; arch drops quickly
Midstance	Sustained arch collapse; calcaneal valgus; medial bulge at navicular	Dynamic arch support absent; midfoot overloads medially
Heel rise / terminal stance	Absent or impaired heel inversion on heel rise (diagnostic); delayed or absent heel off	Core gait finding — PTT normally inverts calcaneus at heel rise; its failure is directly visible here
Push-off	Reduced propulsion through medial column; weight transferred laterally	Unstable medial column unable to transmit push-off forces efficiently
Swing	Slightly shortened swing (antalgic)
Trunk/pelvis	Medial trunk lean over affected side	Compensates for poor medial column stability
Cadence	Reduced speed; wider base	Instability compensation

Key diagnostic gait test: Ask patient to perform a single-leg heel rise on the affected side — inability, pain, or failure of heel to invert confirms PTT insufficiency (Stage 2+).

QUICK REFERENCE: WLV PRESCRIPTION FORM — COMPONENT RATIONALE MATRIX

Component	PF	HL/HR	Morton's	Achilles	PTTD
Base: EVA 2mm	✓	✓	✓	✓	✓
'D' Filler 6mm	✓ (reduce fascial strain)	✓ (reduce pronation/first ray elevation)	✓ (reduce forefoot splay)	✓ (arch/pronation control)	✓✓ (fills arch void; core component)
Cobra Pad	✓ (medial heel cup)	—	—	✓ (insertional)	✓ (medial arch)
Heel Raise 4mm	✓ (equinus)	Consider	—	✓✓ (reduce Achilles load)	Consider
Met Dome	—	—	✓✓ (metatarsal splay)	—	—
Morton's Extension	—	✓✓ (reduce MTPJ dorsiflexion)	—	—	—
RF Varus 3–5°	If pronated	If pronated	—	If pronated	✓✓ (correct hindfoot valgus)
Top Cover: Poron	✓	✓	✓	✓	✓

THE D' FILLER — EXPLAINED (Your Original Question)

From your WLV Simple Insole Prescription Form: 'D' Filler (6mm standard) is a pre-cut block of firm EVA foam (or equivalent material) with a D-shaped cross-sectional profile that is bonded to the plantar surface of the orthotic base beneath the medial longitudinal arch. The flat face of the D contacts the base; the curved face contacts the plantar arch.

Function: It physically fills the concave space under the arch of the insole (created because the base conforms to the foot's arch shape), ensuring:

The insole lies flat in the shoe
Upward arch support force is transferred to the plantar foot
The medial arch is physically supported during the stance phase of gait
It is the primary mechanical means by which the insole controls arch height and reduces pronation

The "6mm standard" refers to the height of the D-shaped EVA block at its apex — this can be modified up (8–10mm for significant flatfoot/PTTD) or down (4mm for a sensitive arch or mild deformity).

*Sources: Miller's Review of Orthopaedics 9th Edition; Gray's Anatomy for Students; Imaging Anatomy Vol 3 (Bones, Joints); Rockwood & Green's Fractures in Adults 10th Ed 2025; WLV Simple Insole Prescription Form (WP004)*You've run out of free credits. Sign up for a free account to continue using Orris.

This is a shared conversation. Sign in to Orris to start your own chat.