Here is the paraphrased version in the same format, with “Orthopaedic Surgery -” added at the beginning of the title.

Orthopaedic Surgery - Casts and Splints

Basics

Casts and splints are used to immobilize injured bones and joints, reduce pain, maintain alignment, and protect healing tissues.

Because casts completely surround the limb and do not readily accommodate acute swelling, most newly injured extremities are initially treated with a splint rather than a circumferential cast.

Splints allow more room for swelling and therefore reduce the risk of pressure-related complications, including iatrogenic compartment syndrome.

Emergency Splinting

In the field, almost any rigid material can be used temporarily as a splint.

Examples include wooden slats, sticks, cardboard, or pillows.

Whatever material is used, adequate padding should be placed between the splint and the skin to protect the soft tissues and prevent pressure injury.

Principles of Immobilization

When a fracture is splinted, the injured bone should be immobilized together with the joint above and the joint below the fracture whenever possible.

This reduces movement at the fracture site and improves stability.

The limb should generally be positioned in a functional and comfortable alignment.

Casting and Splinting Materials

In hospitals and clinics, the two most common materials used for casts and splints are plaster of Paris and fiberglass.

Each has specific advantages and disadvantages.

Plaster of Paris

Plaster of Paris consists of muslin material stiffened with dextrose or starch and impregnated with calcium sulfate hemihydrate.

When water is added, the calcium sulfate crystallizes through an exothermic reaction, releasing heat as the material hardens.

Plaster generally sets within approximately 15 minutes.

Advantages of Plaster

Plaster is highly moldable and allows careful contouring around the extremity.

Its relatively slower setting time gives the clinician more time to apply three-point molding and fracture correction.

This makes plaster particularly useful when precise molding is required.

Fiberglass

Fiberglass is a more modern casting material made from a fiberglass substrate coated with a polyurethane resin.

The resin is activated by moisture and polymerizes as the material hardens.

Fiberglass generally becomes rigid within approximately 7 minutes and is lighter than plaster.

Disadvantages of Fiberglass

Fiberglass can be sticky and difficult to remove if it contacts uncovered skin.

Protective gloves should be used during application.

Its rapid hardening time may also make careful molding more difficult compared with plaster.

Pathophysiology

After musculoskeletal injury, damaged bone and soft tissues release inflammatory mediators, including substances such as interleukin-6.

Movement at an unstable fracture site can increase inflammation, pain, and additional muscle or soft-tissue injury.

Immobilization limits movement between fracture fragments and reduces mechanical irritation.

This generally decreases pain and allows inflammation to gradually settle.

Diagnosis

History

Patients requiring splinting or casting commonly present after trauma with a suspected or confirmed fracture, dislocation, or significant soft-tissue injury.

The mechanism of injury and timing should be documented.

Physical Examination

Before applying any splint or cast, the entire injured extremity should be examined carefully.

The clinician should look for open wounds or open fractures, which may require urgent surgical irrigation and debridement.

Joint Assessment

Nearby joints should be assessed for evidence of dislocation, instability, or additional injury.

Associated injuries can be overlooked if the examination focuses only on the obvious fracture.

Neurovascular Examination

A thorough neurovascular examination should be performed before immobilization.

Motor function, sensation, distal pulses, capillary refill, and skin temperature should be documented.

This provides a baseline for comparison after the splint or cast has been applied.

Swelling and Compartment Syndrome

The limb should also be inspected for swelling, tense compartments, severe pain, or neurologic changes that may indicate compartment syndrome.

Significant swelling influences the choice between a splint and a cast.

Imaging

Painful bones or joints following trauma should generally be assessed with appropriate plain radiographs when fracture or dislocation is suspected.

Imaging should be obtained according to the anatomical region and mechanism of injury.

Treatment

General Principles

During the acute period after injury, a splint is usually preferred because it can accommodate swelling.

After the initial swelling has subsided, a circumferential cast may be applied when longer-term rigid immobilization is required.

Timing of Casting

Many fractures are converted from a splint to a cast approximately 1–2 weeks after injury, once swelling has decreased.

The exact timing depends on the injury, swelling, skin condition, and fracture stability.

Immediate Cast Application

If a circumferential cast must be applied soon after an acute injury, it should generally be split, univalved, or bivalved to allow expansion.

The outer wrapping should remain relatively loose until swelling has stabilized.

Padding

The extremity must be well padded before application of either a splint or cast.

Additional protection should be placed over bony prominences, where pressure injury is most likely to occur.

Felt may be added in vulnerable areas when necessary.

Jewelry Removal

All rings, bracelets, watches, and other constricting jewelry should be removed from the injured extremity before swelling worsens.

Failure to remove jewelry can result in vascular compromise or skin injury.

Position of Function

Whenever possible, the injured limb should be immobilized in a functional position.

This helps minimize stiffness and preserves the ability to use the limb after immobilization is discontinued.

Water Temperature

Very hot water should not be used when activating plaster or fiberglass.

Because setting is an exothermic reaction, excessively warm water may increase heat production and cause a thermal burn beneath the cast or splint.

Avoiding Pressure Points

The clinician should avoid pressing fingertips directly into wet casting material.

Finger indentations may create focal pressure points that can lead to skin breakdown.

The palm of the hand should be used for molding whenever possible.

Three-Point Molding

Three-point fixation or molding is an important principle of fracture immobilization.

Pressure is applied at three carefully selected points to maintain reduction and resist deforming forces.

Proper molding improves fracture stability without creating excessive local pressure.

Open Fractures

Open fractures require urgent operative management but should still be temporarily splinted before surgery.

Immobilization decreases pain, prevents further soft-tissue damage, and protects the wound during transport.

Upper-Extremity Splinting

Proximal Humerus and Humeral Shaft Fractures

For fractures of the proximal humerus or humeral shaft, plaster support may be placed around the shoulder and along both sides of the arm.

A sling is commonly added for comfort and support.

A removable pad may be placed in the axilla so that the skin can be cleaned and the padding replaced as needed.

Humeral Fracture Brace

Once a humeral shaft fracture begins to stabilize, a functional fracture brace may be used.

This allows controlled movement while maintaining circumferential support of the humerus.

Elbow Injuries

The elbow is commonly splinted at approximately 90° of flexion, unless the specific injury requires another position.

Generous padding and a posterior slab are typically used.

A lateral slab may be added for reinforcement.

Hand Position With Elbow Splints

The splint should support the wrist but ideally leave the hand and fingers free when possible.

Once swelling has subsided, an above-elbow cast may be applied if longer immobilization is required.

Forearm and Wrist Injuries

A sugar-tong splint is frequently used for forearm and wrist injuries.

It extends around the elbow with the elbow flexed to approximately 90° and controls both wrist motion and forearm rotation.

MCP Joint Freedom

When applying forearm or wrist splints, the metacarpophalangeal joints should remain free whenever the injury permits.

This allows finger motion and reduces the risk of stiffness.

Below-Elbow Casts

Below-elbow casts should generally allow free movement of the fingers and thumb.

The cast should end proximal enough to avoid restricting the MCP joints unnecessarily.

Hand and Finger Injuries

An ulnar gutter splint, sometimes called a boxer splint, is commonly used for fractures involving the fourth and fifth metacarpals.

The splint is applied along the ulnar aspect of the hand and forearm, creating a supportive gutter.

Ulnar Gutter Splint Technique

A strip of plaster may extend from the tip of the fifth finger to a point approximately 2 inches distal to the antecubital fossa.

Padding or gauze is placed between the fourth and fifth fingers to prevent skin maceration.

Position for Ulnar Gutter Splint

The wrist is usually positioned in approximately 25–30° of extension.

The MCP joints are commonly flexed to approximately 90°, placing the hand in an intrinsic-plus position.

Finger Splints

Individual finger fractures may be immobilized using malleable aluminum finger splints.

These consist of soft aluminum lined with foam and can be cut and shaped to fit the involved digit.

Lower-Extremity Splinting

Femur and Hip Injuries

A Thomas splint is a premade traction splint that may be used temporarily for femoral injuries.

It includes a proximal ring and a longitudinal frame that allows traction to be applied to the leg.

Thomas Splint Sizing

The proximal ring should be approximately 2 inches larger than the circumference of the proximal thigh.

The ring rests against the ischial region and provides countertraction.

Traction Mechanism

A distal strap or ankle hitch is attached to the end of the splint to apply longitudinal traction.

This can temporarily reduce pain, shortening, and movement at the femoral fracture site.

Duration of Thomas Splint Use

A Thomas splint should not remain in place for prolonged periods.

Use beyond approximately 2 hours may place excessive pressure around the ankle hitch and can cause skin injury or necrosis.

Knee and Tibial Injuries

Injuries involving the knee or tibia may be immobilized using an above-knee splint extending to the foot.

The ankle should generally be maintained at approximately 90°.

Padding Around the Knee and Ankle

Special attention should be given to padding around the fibular head and peroneal nerve region, as well as around the malleoli and other ankle prominences.

Poor padding can result in nerve compression or pressure ulceration.

Above-Knee Cast

For stable fractures requiring prolonged immobilization, an above-knee cast may be applied once acute swelling has subsided sufficiently.

Ankle and Foot Injuries

Below-knee splints often combine a posterior slab and a U-shaped stirrup around the ankle.

This configuration provides support while still allowing some accommodation for swelling.

Ankle Position

The ankle should normally be held at approximately 90° of dorsiflexion.

This reduces the risk of developing an equinus position or Achilles tendon contracture.

Below-Knee Casts

Below-knee casts require careful padding, particularly around the malleoli, heel, and anterior tibia.

Pressure over these regions can quickly produce skin breakdown.

Ankle Air Splints

Less severe or more stable ankle injuries may be treated with a removable air-stirrup or ankle air splint.

These provide support while allowing more mobility than a rigid cast.

Activity

Patients should be encouraged to move joints that are not included within the cast or splint.

Maintaining motion helps reduce stiffness, swelling, and muscle weakness.

Joints Prone to Stiffness

The shoulder, elbow, hand, and fingers can become stiff particularly quickly.

Active movement of uninvolved joints should therefore begin as soon as it is safe.

Nursing and Neurovascular Monitoring

After application, the limb should be reassessed to ensure that the splint or cast is not excessively tight.

A repeat neurovascular examination should document motor function, sensation, perfusion, and distal pulses or capillary refill.

Medication

Patients with fractures may require significant pain control during the acute period.

Short-term opioid analgesics may sometimes be necessary, particularly with displaced or high-energy fractures.

Analgesic requirements usually decrease as the injury is stabilized and swelling subsides.

Surgery

Open, intra-articular, unstable, or significantly displaced fractures may require operative fixation.

Splinting is still useful as temporary stabilization while definitive surgical planning is completed.

Follow-Up

Patients with fractures treated initially in a splint should generally be referred to an orthopaedic specialist.

Follow-up commonly occurs within approximately 1 week to reassess alignment, swelling, and the need for surgical treatment.

Serial Radiographs

Fracture reduction and healing should be monitored with repeat radiographs when clinically indicated.

Imaging helps confirm that alignment has been maintained and that fracture union is progressing appropriately.

Complications

Excessively Tight Cast or Splint

A cast or splint may become too tight as swelling increases.

Persistent pain, pressure, numbness, tingling, or a sensation that the cast is constricting should prompt urgent reassessment.

Initial Response to Tightness

If excessive compression is suspected, the splint or cast should be loosened or split promptly.

The limb should then be reexamined to determine whether symptoms improve.

Compartment Syndrome

Persistent severe pain despite loosening should raise concern for compartment syndrome.

The splinting material should be opened completely so that the extremity can be examined.

Pressure Measurements

When the diagnosis remains uncertain, intracompartmental pressure measurements may be obtained.

Elevated pressures in the appropriate clinical setting support the diagnosis of compartment syndrome.

Fasciotomy

Confirmed compartment syndrome requires urgent surgical fasciotomy.

Delayed treatment can result in irreversible muscle and nerve injury and permanent loss of limb function.

Skin Breakdown

Pressure-related skin injury is another important complication.

Adequate padding over bony prominences and careful cast molding help prevent ulcers, abrasions, and skin necrosis.

Patient Monitoring

Patients should be monitored for increasing swelling, worsening pain, neurovascular changes, and signs of compartment syndrome.

Cast or splint fit should be reassessed as swelling changes.

Monitoring Fracture Alignment

Serial radiographs may be required until healing is sufficient to ensure that the fracture has not displaced.

The frequency of imaging depends on fracture type, stability, age, and treatment method.

Patient Teaching

After application of a cast or splint, patients should receive clear instructions regarding warning signs and care of the immobilization device.

They should understand when to seek urgent medical attention.

Warning Signs of Compression

Patients should immediately report increasing pain, numbness, tingling, weakness, excessive swelling, or a feeling that the splint or cast is becoming too tight.

These symptoms may indicate nerve compression, vascular compromise, or compartment syndrome.

Keeping the Splint or Cast Dry

The immobilization device should be kept dry unless it is specifically designed to tolerate water.

Moisture can weaken plaster, irritate the skin, and promote skin breakdown.

Problems With the Cast or Splint

Patients should contact their clinician if the cast becomes loose, cracked, wet, damaged, excessively tight, or painful.

Objects should never be inserted beneath the cast to scratch the skin.

Elevation

During the first 2–3 days, the injured limb should be elevated above the level of the heart whenever possible.

Elevation reduces swelling and pressure within the splint.

Weight-Bearing Restrictions

Patients should follow all prescribed weight-bearing restrictions.

Premature loading may cause loss of fracture reduction, implant failure, or delayed healing.

Exercising Free Joints

Joints not incorporated into the splint or cast should be moved regularly.

Finger or toe movement also helps reduce swelling and preserve mobility.

Frequently Asked Question: Can the Splint Be Removed?

In general, the splint should remain in place unless a clinician removes it for a more detailed examination or replaces it with another device.

Splints usually do not need to be removed for radiographs unless metal components interfere with the images.

If that occurs, a radiolucent alternative can be used.

Frequently Asked Question: Why Is a Cast Not Applied Immediately?

A cast surrounds the entire limb and does not accommodate acute swelling well.

A splint supports only part of the circumference and therefore allows more space for swelling.

For this reason, acute injuries are usually splinted first and converted to a cast after swelling has decreased.

If a splint itself feels excessively tight, it should also be reassessed and loosened promptly.