Ossur Formfit Air Cast Boot – Short Low Top | Pneumatic Walking Cast Boot
The Ossur Formfit Air Short Cast Boot is a lightweight, low-profile pneumatic walking cast boot with an integrated air bladder for adjustable compression. The short low-top, open-toe design is ideal for forefoot injuries, toe fractures, metatarsal fractures, and post-operative foot rehabilitation. For the tall/high-top version, see the Formfit Air Tall.
What this is (and what patients call it)
This is a removable cast boot with an integrated pneumatic air bladder. Many patients call it a walking cast boot, aircast boot, or fracture boot. It fits either the right or left foot — no side selection needed.
Short vs. Tall — Which height do I need?
- This boot (Short Low-Top) — Lower profile, best for forefoot injuries, toe and metatarsal fractures, or when less ankle restriction is needed.
- Formfit Air Tall — Extends higher above the ankle. Best for ankle fractures, severe sprains, or Achilles injuries.
Size Chart & Fit Guide
Universal fit — fits left or right foot.
⚠️ Important: These Boots Fit a Size Range — Not a Single Shoe Size
The extra room allows for bandaging, swelling, post-surgical dressings, and thick socks. When in doubt, go up a size.
Size by Shoe Size
| Size | Men's US Shoe | Women's US Shoe | Part Number |
|---|---|---|---|
| X-Small | 2 – 4.5 | 3.5 – 6 | A-W0300BLK |
| Small | 4.5 – 7.5 | 6 – 8 | A-W0500BLK |
| Medium | 7.5 – 10.5 | 8.5 – 11.5 | A-W0700BLK |
| Large | 10.5 – 12.5 | 11.5 – 13.5 | A-W0900BLK |
| X-Large | 12.5+ | 13.5+ | A-W1100BLK |
Size by Internal Measurements (Short Low-Top)
| Size | Internal Foot Length | Height (Heel → Top) | Boot Weight |
|---|---|---|---|
| X-Small | 8.66" (22.0 cm) | 11.61" (29.5 cm) | 1.82 lb (825 g) |
| Small | 9.45" (24.0 cm) | 11.61" (29.5 cm) | 1.96 lb (890 g) |
| Medium | 10.63" (27.0 cm) | 12.60" (32.0 cm) | 2.27 lb (1030 g) |
| Large | 11.02" (28.0 cm) | 12.60" (32.0 cm) | 2.43 lb (1100 g) |
| X-Large | 12.20" (31.0 cm) | 14.57" (37.0 cm) | 2.65 lb (1200 g) |
Clinical Indications (as prescribed)
- Metatarsal and toe fractures
- Stable ankle and foot fractures
- Grade 2 and Grade 3 ankle sprains
- Post-operative foot and ankle rehabilitation
- Soft tissue injuries with associated edema
Features & Benefits
- Pneumatic air bladder — adjustable compression for edema control
- Short low-top, open-toe design — lower profile for forefoot and midfoot conditions
- Rocker bottom outsole — promotes natural gait
- Breathable liner — moisture management for extended wear
- Lightweight construction — reduces fatigue during recovery
- Universal fit — fits left or right foot
HCPCS Code: L4361 | FSA/HSA Eligible
Shipping: Ships from NJ or CA warehouse in 2–3 business days based on your location.
OrthoTape.com is an authorized Ossur dealer. Authentic product. 6-month manufacturer warranty. Use as directed by a licensed healthcare provider.
Frequently Asked Questions
What is the difference between the Ossur Formfit Air and the Ossur Rebound Air cast boot?
Both are pneumatic cast boots from Ossur. The Rebound Air is the higher-tier line with a more rigid shell, dual-density rocker sole, and closed-toe design. The Formfit Air is the value-tier option — lighter, more affordable, and open-toe. Both provide effective immobilization for fractures and sprains. Your clinician will determine which is appropriate for your injury.
What is a metatarsal fracture and how does a cast boot help it heal?
The metatarsals are the five long bones in the midfoot connecting the ankle to the toes. Metatarsal fractures are among the most common foot injuries, caused by direct impact, falls, or repetitive stress. A cast boot immobilizes the foot to prevent the fractured bone from shifting during healing, while the rocker bottom sole allows a more natural gait. Most metatarsal fractures heal within 6–8 weeks in a cast boot.
What does the pneumatic air bladder do and how do I use it?
The integrated pneumatic air bladder applies gentle, even compression around the foot and ankle to control edema (swelling) and improve fit as swelling changes throughout the day. Pump until you feel firm, comfortable compression — not tight or painful. Release air by pressing the valve if the boot feels too tight, especially in the morning when swelling is typically lower.
How long will I need to wear a cast boot after a foot fracture?
Most stable metatarsal fractures require 4–6 weeks in a cast boot. Ankle fractures may require 6–8 weeks or longer. Your orthopedic surgeon or podiatrist will monitor healing with follow-up X-rays and advise when it is safe to transition out of the boot.
Is this cast boot covered by insurance or Medicare?
The Ossur Formfit Air Short Cast Boot is classified under HCPCS code L4361. Medicare Part B and most commercial insurance plans cover walking cast boots when prescribed by a licensed healthcare provider for a covered diagnosis. This product is also FSA/HSA eligible for out-of-pocket purchases. Contact your insurance provider for prior authorization requirements specific to your plan.
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