How to Apply a Fiberglass Cast

Fiberglass casting is a critical skill for healthcare professionals treating fractures and injuries requiring immobilization. This guide provides step-by-step instructions for proper fiberglass cast application.

Important: Fiberglass casts should only be applied by trained healthcare professionals, including physicians, physician assistants, nurses, orthopedic technicians, and certified athletic trainers.

Materials Needed

• Fiberglass casting tape (appropriate width for the body part)
• Stockinette
• Cast padding (synthetic or cotton)
• Gloves (non-latex recommended)
• Water basin with room temperature or lukewarm water
• Scissors or cast saw for trimming
• Protective covering for work surface

Pre-Application Preparation

1. Patient Assessment

• Assess the injury and confirm casting is appropriate
• Check for contraindications (open wounds, severe swelling, compartment syndrome risk)
• Explain the procedure to the patient
• Position the limb in the correct anatomical position
• Mark any areas of concern or bony prominences

2. Skin Preparation

• Ensure the skin is clean and dry
• Check for any cuts, abrasions, or skin conditions
• Trim excess hair if necessary (do not shave)
• Apply skin protection to bony prominences if needed

General Application Process

Step 1: Apply Stockinette

• Select appropriate size stockinette for the limb
• Pull stockinette over the limb, extending 2-3 inches beyond the planned cast edges
• Smooth out any wrinkles to prevent pressure points
• The stockinette will be folded back over the cast edges at the end

Step 2: Apply Cast Padding

• Start at the distal end (furthest from the body) and work proximally
• Wrap padding in a spiral pattern with 50% overlap
• Use 2-3 layers of padding for most casts
• Add extra padding over bony prominences (ankle bones, wrist, elbow)
• Avoid wrinkles or bunching that could cause pressure points
• Do not stretch the padding - apply with gentle tension only
• Ensure smooth, even coverage throughout

Step 3: Prepare the Fiberglass Tape

• Put on gloves before handling fiberglass tape
• Select the appropriate width tape for the body part being casted
• Prepare water basin with room temperature or lukewarm water (not hot)
• Have all materials ready before opening the foil package

Step 4: Activate and Apply First Layer

• Open one roll of fiberglass tape at a time
• Immerse the roll completely in water for 3-5 seconds
• Gently squeeze (do not wring) to remove excess water
• Begin wrapping at the distal end with the limb in the desired position
• Apply with 50% overlap in a spiral pattern
• Use smooth, even tension - do not pull too tight
• Mold and smooth each layer as you go
• Maintain proper limb position throughout application

Step 5: Apply Additional Layers

• Apply 2-4 layers total depending on the body part and patient size
• Activate each roll just before application
• Smooth and laminate each layer to the previous one
• Work quickly but carefully - fiberglass sets in 3-5 minutes
• Ensure even thickness throughout the cast
• Reinforce high-stress areas (heel, palm) with extra layers if needed

Step 6: Finish the Edges

• Before the cast fully hardens, fold the stockinette back over the edges
• Apply a final layer of fiberglass tape over the folded stockinette
• This creates smooth, padded edges that won't irritate the skin
• Trim any excess material carefully
• Smooth all edges to prevent sharp areas

Step 7: Final Molding and Shaping

• While the cast is still setting (first 3-5 minutes), perform final molding
• Use the palms of your hands (not fingertips) to shape the cast
• Maintain proper anatomical position and alignment
• Create appropriate contours for the body part
• Avoid creating indentations that could cause pressure points
• Support the limb properly until the cast is fully set

Cast Type-Specific Application Instructions

Short Arm Cast Application

Coverage: Extends from below the elbow to the metacarpal heads (knuckles)

Indications: Distal radius fractures, scaphoid fractures, metacarpal fractures

Materials:

• 2-3 inch width fiberglass tape
• 2-3 layers of fiberglass
• Appropriate stockinette and padding

Key Application Points:

• Position wrist in slight extension (10-20 degrees) unless otherwise indicated
• Ensure thumb is free and able to move
• Mold around the thenar eminence (thumb muscle)
• Create a palmar arch to maintain hand function
• Trim cast to allow full finger flexion at MCP joints
• Ensure cast ends 1 inch below elbow crease to allow elbow flexion

Long Arm Cast Application

Coverage: Extends from upper arm to the metacarpal heads

Indications: Forearm fractures, elbow fractures, unstable wrist fractures requiring elbow immobilization

Materials:

• 3-4 inch tape for upper arm
• 2-3 inch tape for forearm and wrist
• 3-4 layers of fiberglass

Key Application Points:

• Position elbow at 90 degrees flexion
• Forearm in neutral rotation (thumb up position) unless otherwise indicated
• Wrist in slight extension
• Apply upper arm portion first, then forearm
• Ensure smooth transition at the elbow
• Mold well around the epicondyles to prevent rotation
• Cast should end 2-3 inches below axilla (armpit)
• Maintain elbow position with support until fully set

Short Leg Cast Application

Coverage: Extends from below the knee to the toes (or metatarsal heads for walking cast)

Indications: Ankle fractures, foot fractures, Achilles tendon injuries

Materials:

• 3-4 inch width fiberglass tape
• 3-4 layers for weight-bearing casts
• Extra reinforcement for heel and sole if weight-bearing

Key Application Points:

• Position ankle at 90 degrees (neutral position) unless otherwise indicated
• Foot in slight eversion (5 degrees) for stability
• Mold well around malleoli (ankle bones)
• Create a smooth heel cup for comfort
• For walking casts, reinforce the heel and sole with extra layers
• Ensure cast ends 1-2 inches below fibular head to avoid peroneal nerve compression
• Toes should be visible and able to wiggle freely
• Check for proper arch support

Long Leg Cast Application

Coverage: Extends from upper thigh to the toes

Indications: Tibial fractures, knee injuries, unstable ankle fractures requiring knee immobilization

Materials:

• 4-6 inch tape for thigh
• 3-4 inch tape for lower leg
• 4-5 layers for adequate strength
• Significant reinforcement for weight-bearing casts

Key Application Points:

• Position knee in slight flexion (10-15 degrees)
• Ankle at 90 degrees neutral position
• Apply lower leg portion first, then extend to thigh
• Mold well around femoral condyles to prevent rotation
• Create smooth transition at the knee
• Cast should end 2-3 inches below groin
• Ensure adequate padding in popliteal fossa (back of knee)
• Reinforce heel and sole if weight-bearing is allowed
• May require assistant to maintain position during application

Post-Application Care

Setting Time

• Initial set: 3-5 minutes
• Weight-bearing strength: 20-30 minutes
• Full cure: 24 hours
• Keep the limb elevated and supported during the setting period

Patient Instructions

Provide the patient with clear cast care instructions including:

• Keep the cast dry (unless using waterproof liner)
• Do not insert objects inside the cast
• Watch for signs of complications (excessive swelling, numbness, severe pain)
• Elevate the limb to reduce swelling
• Exercise fingers or toes to maintain circulation
• When to seek immediate medical attention

Quality Check

Before the patient leaves, verify:

• Proper fit - not too tight or too loose
• Smooth edges with no sharp areas
• Adequate padding at all edges
• Proper position and alignment
• Patient can move fingers/toes with normal color and sensation
• No areas of excessive pressure or discomfort

Troubleshooting Common Issues

Cast Too Tight

• Remove immediately if neurovascular compromise is suspected
• Prevention: avoid excessive tension during application
• Use adequate padding

Cast Too Loose

• May require replacement for proper immobilization
• Prevention: proper molding during setting, account for swelling reduction

Rough Edges

• Can be smoothed with a cast file or additional padding
• Prevention: proper edge finishing technique

Indentations or Pressure Points

• May require cast removal and reapplication
• Prevention: use palms (not fingertips) for molding, adequate padding

Safety Considerations

• Always assess neurovascular status before, during, and after application
• Monitor for compartment syndrome, especially in the first 48 hours
• Educate patients on warning signs requiring immediate attention
• Document the casting procedure, materials used, and patient education provided
• Follow your facility's protocols and guidelines
• Maintain proper infection control practices

Professional Development

Proper casting technique requires hands-on training and practice. Healthcare professionals should:

• Complete formal training in casting techniques
• Practice under supervision before independent application
• Stay current with best practices and new materials
• Attend continuing education courses on orthopedic care
• Follow manufacturer guidelines for specific products

For more background on the materials used in this process, visit our Fiberglass Cast Tape (Fiberglass Casting Tape) Guide.