Basic principles

First, Do No Harm

1. Make sure that the potential complications of applying and maintaining a cast or splint are less severe and less likely than the complications of an untreated injury.

2. A poorly made splint/cast can result in pressure sores, compression neuropathies, joint stiffness, and complex regional pain syndrome.

3. Never place a circumferential rigid dressing (cast) over an increasingly edematous limb because compartment syndrome can result.

4. Elastic bandages such as an all cotton elastic (ACE) bandage should be applied loosely so that the elasticity can accommodate any future swelling.

5. Elbows, forearms, and the lower leg and foot have the highest risk of compartment syndrome after cast application. Use caution when applying a cast in the acute setting.

6. Because plaster can expand, it is better to use plaster rather than the more rigid fiberglass cast in the acute setting.

7. Plaster and fiberglass cure with an exothermic reaction; thus inadequate padding, lack of exposure to ambient air (under a blanket), or use of water that is above room temperature can result in thermal injuries, including second-degree burns.

What to Immobilize

1. For intraarticular or periarticular fractures, the bone proximal and distal to the joint involved should be included (one above and one below).

2. For extra-articular fractures, immobilize one joint above and one joint below.

3. Immobilizing more joints than is necessary can result in permanent iatrogenic loss of joint motion.

4. Immobilization of fewer joints than is necessary can result in fracture displacement, neurovascular injury, and unnecessary pain and suffering.

Figure 12-1

Figure 12-2

What Position to Immobilize

1. Unless a pressing reason exists to do otherwise, each joint should be immobilized in the optimal position to retain joint mobility after the cast/splint is removed.

Figure 12-3

Figure 12-4

Figure 12-5

Figure 12-6

Figure 12-7

Figure 12-8

Cast Removal

1. Overview

a. A cast saw is an oscillating saw designed to cut hard cast material while minimizing trauma to soft material, such as cotton padding and skin.

(1) The oscillations generate significant heat and can easily burn a patient.

(2) Approximately 1% of cast removals are associated with a cast saw burn (Figure 12-16).

b. A cast saw is necessary for removal of fiberglass casts (Figure 12-17).

c. Plaster casts can be unraveled after they are soaked in water for several minutes; however, finding the leading end of the plaster strip can be difficult.

d. Do not attempt to place any cast if a cast saw is not available, because emergent removal or trimming of the cast may be necessary.

e. A cast spreader can be very helpful in separating the two halves of a cast after they have been split (Figure 12-18).

f. We recommend that a cast saw be attached to suction to limit the volume of aerosolized particulate debris on clothes and in your lungs (Figure 12-19).

g. Removal of waterproof casts is associated with a higher risk of cast saw burns because the padding is less heat resistant and thinner than is conventional cast padding.

2. Technique

a. It is important to use an “up, over, down” technique when cutting a cast.

b. The cast saw should be pushed directly down into the cast (Figure 12-20). Your index finger should rest on the cast to limit the excursion of the cast saw.

c. The saw should then be removed by coming straight back up.

d. The saw should then be moved longitudinally to the next point on the cast.

e. The saw is then reinserted using the same technique.

f. Intermittently check the temperature of the blade. The blade can be cooled with an alcohol wipe.

g. Never drag the cast saw along the cast. This technique significantly increases the risk of a cut or a burn.

Figure 12-16

Figure 12-17

Figure 12-18

Figure 12-19

Figure 12-20

Materials

Stockinette

1. Stockinettes are available in 1- to 6-inch widths and in rolls of several yards in length.

2. Stockinettes may be used as a border to provide a more finished appearance to casts (Figure 12-21).

3. Stockinettes may be used for traction set-up (Figure 12-22).

Figure 12-21

Figure 12-22

Plaster

1. Plaster is available in sizes ranging from 1- to 6-inch-wide rolls and strips (Figure 12-26).

2. The plaster content and quality of the rolls and strips varies by manufacturer.

3. We prefer Gypsona because it has a high plaster content, makes a nice, smooth finish on the outside, and feels silky to apply.

4. Plaster can be used for any splint or cast.

5. Plaster holds a mold better than fiberglass does and is the material of choice when a reduction is required.

6. Plaster expands more than fiberglass and is better suited to the acute setting.

7. Unlike fiberglass, plaster loses all structural integrity in water and must be kept dry.

8. A plaster splint/cast will take 24 hours to fully cure.

9. Avoid air pockets or bubbles in the plaster, which form a stress riser inside the cast and lead to structural failure.

10. Avoid direct contact between the skin and plaster, which can result in abrasions and lacerations.

Figure 12-26

Fiberglass

1. Fiberglass is available in a variety of sizes and colors ranging from 1 to 6 inches and from hot pink to army green (Figure 12-27).

2. Fiberglass takes just a few minutes to reach near full structural integrity and is more resistant to deformation than is plaster. Because of these qualities, molding with fiberglass is much more difficult than molding with plaster.

3. Water does not compromise a fiberglass cast, and waterproof cast padding can be used if a patient intends to go in the water or if it is suspected he or she will do so.

4. Fiberglass can be used to hold a nondisplaced fracture in position.

5. Use cut-to-length fiberglass splints with caution:

a. Pad the edges (which can be as sharp as cut glass).

b. Use the correct width.

c. Place the padded side toward the skin.

6. Be sure to wring out any excess moisture from the fiberglass after activating it in water to prevent maceration of the cast padding.

7. Do not use a fiberglass cast in the acute setting unless the patient will be under close observation in the hospital, and never use it in the acute setting on an obtunded patient.

8. Avoid direct contact between the skin and fiberglass, which can result in abrasions and lacerations.

9. Fiberglass that is colored can leave a stain on clothes or skin.

Figure 12-27

Elastic Cast Material

1. Elastic cast material is available in sizes ranging from 1 to 3 inches.

2. We use 3M Soft cast (Figure 12-28).

3. Elastic cast material can be used for young children who do not require rigid immobilization and are unlikely to tolerate cast removal with a saw.

4. Avoid using elastic cast material if a reduction was attempted.

5. Avoid direct contact between the skin and elastic cast material, which can result in abrasions and lacerations.

Figure 12-28

Splint production basics

Padding

Figure 12-31

Figure 12-32

Figure 12-33

Figure 12-34

Figure 12-35

Figure 12-36

Figure 12-37

Types of Splints

1. Plaster onlay splint (Figure 12-38):

a. The cast padding is applied to the limb, then the slab of plaster is laid onto the cast padding.

b. Cast padding is then rolled over the plaster.

c. This technique produces the best conforming and most versatile splint.

2. Plaster prepadded splint (Figure 12-39):

a. Instead of placing cast padding directly on the limb, a splint can be prepadded and applied as a unit.

b. A plaster prepadded splint is best for coaptation splints.

c. Commercial prepadded plaster splint material is available.

d. Prepadded plaster splint material can be placed inside a stockinette for additional versatility.

3. Fiberglass prepadded splint:

a. A fiberglass prepadded splint is a strip of fiberglass inside cast padding material that can be cut to any desired length.

b. Commercially made fiberglass prepadded splints are available in a variety of widths from 3 to 6 inches. We do not recommend use of this type of product.

Figure 12-38

Figure 12-39

Plaster Onlay Splint

1. Place two layers of cast padding to allow a 1- to 2-cm cuff of padding proximal and distal to the plaster (Figure 12-40).

2. Measure out the correct length of splinting material (Figure 12-41). Keep in mind that plaster will shrink in water by approximately 5%.

3. Prepare 10 to 12 layers of splinting material of the measured length and adequate width (Figure 12-42).

4. Activate the plaster by placing it in tepid water.

5. Allow the plaster to soak until it is softened (Figure 12-43).

6. Remove any excess moisture from the plaster (Figure 12-44).

7. Wring any air pockets or bubbles out of the plaster by running the strip between two fingers (Figures 12-45 and 12-46).

8. Apply the plaster slab to the limb.

9. If the slab is too long, either fold it back (Figure 12-47) or cut it to size (Figure 12-48).

10. Overwrap with cast padding (Figure 12-49).

11. Overwrap with an elastic or self-adherent bandage (Figure 12-50).

Figure 12-40

Figure 12-41

Figure 12-42

Figure 12-43

Figure 12-44

Figure 12-45

Figure 12-46

Figure 12-47

Figure 12-48

Figure 12-49

Figure 12-50

Plaster Prepadded Splint

1. Measure out the correct length of splinting material (Figure 12-51). Keep in mind that plaster will shrink in water by approximately 5%.

2. Prepare 10 to 12 layers of splinting material of the measured length and adequate width (Figure 12-52).

3. Roll out four layers of cast padding on a flat surface a few centimeters longer than and twice as wide as the slab of plaster (Figure 12-53).

4. Place a strip of cast padding twice the length of the plaster slab in the center of the cast padding (12-54 and 12-55).

5. Activate the plaster by placing it in tepid water.

6. Allow the plaster to soak until it is softened (see Figure 12-43).

7. Remove any excess moisture from the plaster (see Figure 12-44).

8. Wring any air pockets or bubbles out of the plaster by running the strip between two fingers (see Figures 12-45 and 12-46).

9. Place the plaster slab in the center of the padding material (Figure 12-56).

10. Fold over the cast padding to cover the edges of the plaster slab (Figure 12-57).

11. Fold a double-length strip of padding to cover any exposed plaster (Figure 12-58).

12. Place the splint into a stockinette for extra padding if desired (Figure 12-59).

13. Apply the prepadded splint to the limb (see Figure 12-39).

14. If the splint material is too long, either fold it back or cut it to size.

15. Overwrap the splint with an elastic or self-adherent bandage (Figure 12-60).

Figure 12-51

Figure 12-52

Figure 12-53

Figure 12-54

Figure 12-55

Figure 12-56

Figure 12-57

Figure 12-58

Figure 12-59

Figure 12-60

Cast production basics

Types of Casts

1. Plaster cast:

b. Advantages of a plaster cast:

(1) A plaster cast will accommodate a small amount of edema.

(2) A plaster cast is the best mode of immobilization to hold a fracture reduction.

c. Disadvantages of a plaster cast:

(1) Even a well-made plaster cast will begin to crumble after 6 weeks and may need to be reinforced with a fiberglass outer shell.

(2) Creating a plaster cast is technically more demanding.

(3) Creating a plaster cast is messy.

Figure 12-61

Figure 12-62

Figure 12-63

Figure 12-64

Figure 12-65

Figure 12-66

Figure 12-67

Plaster Cast

1. Cut two pieces of stockinette, one for the proximal end and one for the distal end.

2. Place the stockinette onto the limb (Figure 12-68).

3. Place two layers of cast padding to allow a 1- to 2-cm cuff of padding proximal and distal to the plaster (Figure 12-69).

4. Fold back the stockinette to create a neat edge (Figure 12-70).

5. Activate the plaster by placing it in tepid water.

6. Allow the plaster to soak until it is softened (Figure 12-71).

7. Do not wring out the plaster: keep it sloppy wet (Figure 12-72).

8. Apply the plaster to the limb.

a. Begin with a circumferential wrap at one end.

b. Progress to the other end while overlapping each layer by 50%.

c. Return to the starting point while overlapping each layer by 50%.

d. Avoid seams on the concave side of a joint: “span the fossa” (Figure 12-73).

9. If the plaster encroaches on the cuff of the cast padding or is in contact with the skin, wait until it has cured (5 to 10 minutes) and then trim it with a cast saw.

10. Tips and tricks:

a. Around elbows, knees, and ankles, apply a four-layer plaster slab to the convex side of the joint to minimize bulk on the concave side.

b. Roll four times around either end of the cast to ensure that both ends are rigid.

c. To laminate the cast as you go, smooth out the plaster with the hand not holding the plaster roll.

(1) While pulling the roll of plaster toward you with your right hand, the left hand should mirror that motion while pressing the heel of your hand against the cast (see Figure 12-63).

(2) While pushing the roll of plaster away from you with your left hand, the right hand should mirror that motion while pressing the heel of your hand against the cast (Figure 12-74).

d. To get around the thumb-index web space, either twist the roll 360 degrees or pinch the sheet of plaster (Figures 12-75 and 12-76).

e. To make a turn:

(1) Lift the plaster away from the limb.

(2) Pinch one end of the strip (Figure 12-77).

(3) Angle the plaster and begin the roll (Figure 12-78).

(4) Smooth out (laminate) the dog ear (Figures 12-79 and 12-80).

f. When the roll of plaster begins to unravel, it is called a “banana.”

(1) If a banana occurs, push the plaster back in and pinch the end closed (Figures 12-81 and 12-82).

(2) If a banana cannot be fixed, cut off the roll and begin a new roll.

Figure 12-68

Figure 12-69

Figure 12-70

Figure 12-71

Figure 12-72

Figure 12-73

Figure 12-74

Figure 12-75

Figure 12-76

Figure 12-77

Figure 12-78

Figure 12-79

Figure 12-80

Figure 12-81

Figure 12-82

Fiberglass/Elastic Cast

1. Cut two pieces of stockinette, one for the proximal end and one for the distal end.

2. Place the stockinette onto the arm.

3. Place two layers of cast padding to allow a 1- to 2-cm cuff of padding proximal and distal to the cast material.

4. Fold back the stockinette to create a neat edge.

5. Activate the cast material by placing it in tepid water.

6. Remove any excess moisture from the casting material (Figure 12-83).

7. Apply the casting material to the limb.

a. Begin with a circumferential wrap at one end.

b. Progress to the other end while overlapping each layer by 50%.

c. Return to the starting point while overlapping each layer by 50%.

d. Avoid seams on the concave side of a joint: “span the fossa” (Figure 12-84).

e. The casting material can be cut with trauma shears to facilitate turns and passage through web spaces (Figure 12-85).

8. If the casting material encroaches on the cuff of the cast padding or is in contact with the skin, wait until it has cured (5 to 10 minutes) and then trim it with a cast saw.

9. Tips and tricks:

a. Around elbows, knees, and ankles, shuffle the casting material back and forth over the convex side of the joint to minimize bulk on the concave side (Figure 12-86).

b. Roll four times around either end of the cast to ensure that both ends are rigid.

Figure 12-83

Figure 12-84

Figure 12-85

Figure 12-86

Common errors

1. Padding is inappropriate:

a. Too little padding can lead to pressure necrosis and saw burns.

b. Too much padding can result in inadequate immobilization and does not accommodate swelling.

c. Wrinkled padding can cause pressure necrosis.

2. Activating plaster in hot water:

a. Casting material often is activated in hot water to reduce the amount of time needed for the cast to harden.

b. The faster casting material sets, the more heat is produced.

c. Heat produced by fast-setting casting material places the patient at risk for thermal injury.

3. Cast material thickness too thick:

a. The more material that is used, the larger the exothermic reaction and the greater the risk of thermal injury.

4. Failure to allow the splint or cast to fully harden:

a. A busy clinician may leave a recently applied splint or cast on a pillow or on a stretcher.

b. Static pressure from the pillow or stretcher can increase the temperature at that pressure point, leading to thermal injury.

c. Any molding may be lost if the casting material has not hardened. This consequence most commonly occurs when applying a splint or cast around the ankle; as a result, the foot falls into equinus.

5. The cast is wrapped too tightly:

a. COMPARTMENT SYNDROME!

6. The cast or splint is applied unevenly:

a. The tendency exists to apply more of the splint around the apex of the injury.

b. An unevenly applied cast or splint is most commonly detected on postapplication radiographs (Figure 12-87).

7. The cast or splint is not laminated:

a. Lack of lamination results in a weak splint or cast.

b. Lack of lamination is most commonly detected on postapplication radiographs as an onion-skinning appearance (Figure 12-88). The plaster should be one solid line (Figure 12-89).

8. The wrong joints are immobilized or the joints are immobilized in the wrong position:

a. Immobilizing more joints than is necessary can result in permanent iatrogenic loss of joint motion.

b. Immobilization of fewer joints than is necessary can result in fracture displacement, neurovascular injury, and unnecessary pain and suffering.

c. Immobilization in an incorrect position can result in both fracture displacement and iatrogenic loss of joint motion.

9. The cast saw is used in an inappropriate fashion:

a. The cast saw should never be dragged along a cast.

Figure 12-87

Figure 12-88

Figure 12-89