Lateral Ankle
Instability
Restores neuromuscular control, provides lateral support, and stabilizes the ankle — custom congruent to every patient's foot model.
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Lateral ankle instability starts at the ligaments, not the bone.
The lateral ligament complex is the primary restraint against inversion of the ankle. When these ligaments are repeatedly sprained or chronically lax, the ankle loses its mechanical and neuromuscular stability — creating a cycle of re-injury that worsens with each episode.
The root cause is structural and neuromuscular. Without restoring lateral stability mechanically, rehabilitation alone rarely breaks the cycle of chronic instability.
Ligament laxity
Each sprain further elongates the lateral ligaments — reducing their ability to restrain inversion and protect the joint.
Proprioceptive loss
Damaged ligaments impair the ankle's ability to sense position — the neuromuscular feedback loop that prevents re-injury breaks down.
Compounding instability
Each episode of giving way further damages surrounding structures — peroneal tendons, cartilage, and joint surfaces degrade over time.
The P3 restores lateral stability from the first step.
Custom-fabricated to your patient's exact foot shape and clinical positioning.
Three interventions.
One precise solution.
The P3 doesn't mask instability — it addresses the mechanical and neuromuscular drivers behind it.
Lateral oblique rearfoot post
A lateral oblique EVA post — superior to standard posts — controls the hindfoot through the full gait cycle, reducing the inversion moments that trigger giving way.
Dual flanges
Medial and lateral flanges maintain control throughout gait — providing the structural boundary the lax ligaments can no longer enforce.
Congruent shape
Precise fit distributes load across the entire plantar surface, provides continuous proprioceptive input, and changes the muscle firing sequence — rebuilding the neuromuscular stability the ankle has lost.
It's not just alignment. It's how your muscles fire.
The shape of what's under your foot determines how hundreds of muscles sequence during every gait cycle. Change that shape precisely — and you change the neuromuscular pattern that stabilises the body.
- Neurological feedback — congruent shape provides continuous proprioceptive input, rebuilding the neuromuscular awareness the damaged ligaments have compromised.
- Muscle sequence in gait — hundreds of muscles fire differently based on what's under your foot. Root shape corrects this sequence, improving peroneal activation and lateral stability.
- True lateral stabilization — the P3's dual flanges and lateral oblique post provide the structural boundary the lax ligaments can no longer enforce. Less giving way means less damage.
- Load distribution — volume congruency distributes pressure evenly across the plantar surface, eliminating the concentrated lateral loading that triggers inversion episodes.
Shape is everything.
What separates Root from generic supports is the precise morphological shape captured from the patient's foot — held in the exact clinical position the clinician chose.
The Root orthotic matches the precise alignment the clinician held the foot in during scanning. This congruency stabilizes the ankle and redistributesutes load across the correct structures.
Modern Root
Width adjusted considering both borders. Default for all Root models.
Traditional Root
Justified to the lateral border. Medial width reduced. Used for specific clinical indications.
Modern Root shape process
- Forefoot balanced to rearfoot — the forefoot-to-rearfoot relationship is optimised as the first step in shape modification.
- Fat pad expanded ~3mm — expanding the fat pad in the heel ensures the device fills the calcaneal contour precisely.
- Arch lowered ~3mm — creates optimal heel-to-arch-to-met-head geometry. Not applied to foam impressions.
- Width tuned to both borders — medial and lateral widths are both considered, giving a foundation that matches the patient's actual foot width.
*Subtalar joint neutral is found by palpating the talus head against the navicular. The neutral position can present many joint-on-joint and bone-on-bone relationships and varies from person to person. An everted or inverted calcaneus may be a neutral position for an individual person. Biomechanical evaluation required.
How you hold the foot is what we build.
Root is not just the orthotic — it's the clinician's positioning, captured and preserved in the device. After scanning, FootID Pro asks the questions no other lab asks.
After every scan, we need to know:
- Was the subtalar joint held in neutral?
- Was the midtarsal joint maximally pronated — loading the 5th metatarsal head?
- Was the midtarsal joint maximally supinated — loading the 1st metatarsal head?
- Was the forefoot brought perpendicular to the rearfoot?
- Was a forefoot-to-rearfoot balance bisection achieved at 90° relative to the calcaneal bisection?
The positioning of those 19 joints in the foot is what gives us the shape.
CAD/CAM fabrication
- Scan or cast captured — clinician captures foot morphology via FootID Pro, holding the subtalar joint in the chosen clinical position.
- Shape modification applied — forefoot balanced to rearfoot, fat pad expanded, arch adjusted using Root's design.
- Technical staff review — every device reviewed against Traditional Root, Modern Root, Blake Inverted, or Accommodative principles.
- Fabricated to the shape — the polypropylene frame and EVA post are fabricated to match the submitted shape precisely.
See how the scan becomes an order.
Watch Kevin capture a foot, confirm the clinical position, and send a Root order — start to finish.
Variation converted to anatomy-match accuracy by impression & fabrication method
How closely each method preserves the patient’s intended foot shape. Scale: 0–100%, where 100% = optimal congruence.
Plaster bandage is wrapped around the foot in the clinician’s prescribed corrected position, setting into a precise negative of the foot’s contour.
The foot is pressed into a crushable foam box, leaving a negative impression of the plantar surface.
An existing positive model from the patient’s previous orthotics is reused — KevinRoot accepts models from any lab, with frame-contour variance as low as 1%.
A digital scanner such as FootID Pro captures the foot surface as a 3D model.
A fiberglass casting sock is applied over the foot and cures to capture its contour.
Pedobarography captures the patient’s plantar pressure distribution (static or dynamic) at 1:1 scale — used with arch height and shoe size to select a redimold positive model, not to capture true 3D contour.
A direct-molding system using prefabricated, size- and arch-based positive models (33 in total) rather than an individual foot impression.
Heated material is vacuum-pressed over a plaster positive model, drawing it intimately into every contour.
The frame is 3D printed by selective laser sintering (SLS) directly from the CAD-designed digital frame.
A positive model is CNC-milled (CAD/CAM) from an STS, 3D scan, plaster, or foam impression, then the frame is vacuum formed over it.
A CNC machine subtractively mills the frame from a block of polypropylene or EVA per the digital design.
*Redimold has no physical or digital foot impression — patient-foot-to-cast congruent accuracy is unavailable. Variation from positive model to frame is low.
How your foot shape becomes a precision frame.
The journey from clinical capture to finished orthotic frame is where Root's expertise lives. Every step preserves the shape and position the clinician chose.
- Foot impression captured — the clinician captures the foot using their preferred method. The fashion in which the foot is held directly affects the outcome of the Root Shape congruency against the foot.
- Positive model created — the impression becomes a physical plaster model or a digital CAD/CAM model via FitFoot360. Digital models are stored indefinitely.
- Root technicians modify the shape — using FitFoot360, technicians apply the Modern Root shape process. Every modification is reviewed against the clinical prescription.
- Orthotic frame fabricated — the frame is vacuum formed over the positive model or 3D printed, pressing the material precisely to the shape. Covers, postings, and modifications are then applied.
FitFoot360 Foot Model
- Root digital model stored indefinitely → recalled for future pairs
- Root technicians modify the digital shape in real-time: arch, heel, width, postings
- Vacuum formed over CAD/CAM positive model, direct milled or 3D printed Root Frame — replicable, consistent, precise
Real-time control over shape, function, and fit.
FitFoot360 gives Root's technicians complete digital control over every dimension of the orthotic frame — in real time. What once required physical carving and guesswork is now precise, repeatable, and stored permanently for every patient.
Digital positive model
Stored indefinitely. Future pairs, replacements, or modifications can be fabricated from the exact same shape without a new impression.
Real-time shape modification
Root technicians control arch, heel, width, and postings directly in the software.
Every parameter visible
Heel cup depth, frame reinforcement, ray cut-outs, flanges, and more are set per patient, not per template.
Plaster and foam digitisation
Physical models can be digitised for permanent storage. Note: digitising may not perfectly replicate the intimate contours achieved when vacuum forming directly over plaster.
Built to their spec. Built for their foot.
Every parameter of the P3 is set to the individual patient — material, posting, heel-cup depth, and covers are all chosen for their anatomy and gait, never an average.
Rigidity is selected per patient weight — so the shell provides exactly the lateral control that specific patient's ankle instability requires.
The lateral oblique angle is built into the positive model of the patient's foot — providing rearfoot control superior to a standard post, congruent to their anatomy.
Cast directly from the patient's calcaneus, the deep cup fits their heel precisely — controlling their specific degree of inversion and eversion, not an average.
Trimmed to the patient's toe line, so contact and pressure distribution match their exact foot geometry.
Selected for shoe compatibility — keeps the device stable inside the shoe while the custom shell delivers lateral control above.
Full-length cushioning that absorbs impact without compromising the lateral stability the device is designed to deliver.
What changes when your foundation is corrected.
Addressing lateral ankle instability biomechanically creates cascading improvements across the entire kinetic chain.
- Restored lateral stability — the lateral oblique post and dual flanges provide the structural restraint the damaged ligaments can no longer deliver.
- Reduced re-injury risk — controlling inversion at its source breaks the cycle of chronic sprains that progressively worsen joint integrity.
- Rebuilt proprioception — congruent shape provides continuous sensory feedback, retraining the neuromuscular control the ankle has lost.
- Full kinetic chain relief — corrected ankle mechanics reduce compensatory strain in the knee, hip, and lumbar spine.
Designed to stabilize the ankle.
A lateral oblique rearfoot post — superior to standard posts — controls the hindfoot while dual medial and lateral flanges maintain stability throughout gait. Fabricated from a positive model of the patient's foot, the P3 improves balance, enhances sensory feedback, and reduces the mechanical vulnerability that leads to chronic instability.
The full picture.
Everything you need to prescribe.
- Peroneal tendinitis
- Peroneal tendinosis
- Talofibular ligament ruptures/sprains
- Peroneal tendon subluxation
Recommended for
- Lateral ligament laxity
- Peroneal tendon pathology
- Chronic ankle instability
- Pre-surgical treatment prior to Brostrom procedure
Designed to improve function and neuromuscular control of the ankle — this device increases balance, provides lateral support, and enhances sensory feedback for patients with chronic instability.
A lateral oblique rearfoot post delivers rearfoot control superior to standard posts. Dual medial and lateral flanges maintain control throughout gait. Fabricated from a positive model of the patient's foot, fully modifiable at the practitioner's discretion.
- L3000 (UCB)
- L3010 (longitudinal/metatarsal support)
- L3020 (arch support)
- L5000 (filler)
Final coding and billing are the provider's responsibility
Delivery Time
- Standard: 2 weeks
- Expedited: Available upon request
Lateral Ankle Instability
The lateral ligament complex is the primary restraint against inversion of the ankle — protecting the joint through every step, change of direction, and landing. When these ligaments are repeatedly sprained or chronically lax, the ankle loses its mechanical and neuromuscular stability, creating a cycle of re-injury that worsens with each episode.
A Condition That Compounds Without Intervention
Lateral ankle instability develops when acute sprains fail to heal fully, or when ligament laxity allows the joint to move beyond its normal range. Each subsequent sprain further compromises proprioceptive function — the ankle's ability to sense and respond to position. Without intervention, the condition progresses from mechanical instability to chronic neuromuscular dysfunction.
Peroneal Tendinitis — Inflammation of the peroneal tendons from overuse or repetitive inversion stress. Presents as lateral ankle pain and swelling, worsening with activity.
Peroneal Tendinosis — Chronic degeneration of the peroneal tendon from sustained overuse. No acute inflammation — the tendon is deteriorating, not just irritated. Presents as persistent lateral pain and weakness.
Talofibular Ligament Sprain/Rupture — Disruption of the anterior talofibular or calcaneofibular ligaments — the most commonly injured structures in ankle sprains. Grades I–III determine the degree of laxity and required intervention.
Peroneal Tendon Subluxation — Displacement of the peroneal tendons from their groove behind the lateral malleolus. Presents as snapping or popping with dorsiflexion, often following acute trauma.
Diagnosis
Clinical assessment includes the anterior drawer and talar tilt tests to evaluate ligament integrity and mechanical laxity. Stress X-rays assess joint stability under load. MRI and ultrasound are used to evaluate peroneal tendon condition and the degree of ligament disruption when conservative treatment planning requires a clearer picture.
Treatment Pathway
First-line treatment includes orthotics, rest, NSAIDs, and neuromuscular rehabilitation. Custom orthotics are most effective when introduced early — restoring mechanical stability while proprioceptive retraining rebuilds neuromuscular control. If little progress is seen at 2–3 months, bracing or immobilization is indicated. Brostrom ligament reconstruction becomes a consideration after 6 months without meaningful recovery.
The P3 is designed to be part of the first-line response — restoring lateral stability from the first step, supporting the ankle while it heals.
The right device
for the right diagnosis.
P3 is indicated for chronic ankle instability, peroneal tendon pathology, and lateral ligament dysfunction.
Prescribe with confidence across these conditions.
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