Radial Gutter Splinting

In general, splints are applied to decrease movement and provide support and comfort by stabilizing an injury. Splints are primarily used to secure nonemergency injuries to the bones and soft tissues of an extremity until they can be evaluated by a consultant such as an orthopedic surgeon. Splints can also be used to assist in primary healing or to achieve temporary immobilization of an extremity before surgery (eg, in a patient with an open fracture).[1, 2, 3]

Unlike casts, splints are noncircumferential and often preferred in the emergency department (ED) setting, in that injuries are often acute and continued swelling can occur. All patients with injuries that are splinted should be referred for evaluation by a consultant in a timely fashion (usually within 2-7 days, depending on the reason for splinting).[4]  (See the image below.)

For information on surgical treatment of such injuries, see Carpal Fractures; Metacarpal Fractures; Radius, Distal Fractures; Hand, Metacarpal Fractures and Dislocations; and Hand, Phalangeal Fractures and Dislocations.

A radial gutter splint can be used for various injuries, including the following:

• Soft-tissue injuries to the second and third fingers
• Fractures of the second and third metacarpals
• Fractures of the second and third phalanges
• Positioning for rheumatoid arthritis
• Lacerations over the joints of the second and third phalanges or metacarpals

There are no absolute contraindications for radial gutter splinting. The following injuries require immediate evaluation or intervention by a consultant (eg, orthopedic surgeon, hand surgeon, or plastic surgeon) and should not be treated with splinting alone:

• Complicated fractures
• Open fractures
• Injuries with associated neurovascular compromise

Anatomy

The hand contains five metacarpal bones. Each metacarpal has a base, a shaft, a neck, and a head. The first metacarpal bone (thumb) is the shortest and most mobile. It articulates proximally with the trapezium. The other four metacarpals articulate with the trapezoid, capitate, and hamate at the base. Each metacarpal head articulates distally with the proximal phalanges of each digit. The hand also contains 14 phalanges. Each digit contains three phalanges (proximal, middle, and distal), except for the thumb, which has only two. (See Hand Anatomy.)

Procedural planning

Some orthopedic surgeons recommend a volar splint instead of a radial gutter splint for angulated neck fractures of the second and third metacarpals. One should check with the orthopedist who performs follow-up care to find out which type of splint he or she recommends.

A radial gutter splint is often applied for uncomplicated metacarpal fractures. When a metacarpal fracture is present, a clinical examination for malrotation should also be performed. With the second through fifth fingers slightly flexed, the nail beds of adjacent fingers should lie in the same plane. With 90° flexion of the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints and with extension of the distal interphalangeal (DIP) joints, the second through fifth fingers should point toward the scaphoid. It may be useful to compare with the unaffected hand.

In the second and third metacarpals, 10° of angulation is acceptable; in the fourth metacarpal, 20° of angulation is acceptable; and in the fifth metacarpal, 30° of angulation is acceptable. Higher degrees of angulation often necessitate surgery.

Equipment used in radial gutter splinting includes the following (see the image below):

• Stockinette
• Padding (eg, Webril)
• Ready-made fiberglass (eg, Orthoglass) or plaster splinting material (eg, plaster of Paris), eight to 10 sheets, 3-4 in. (~7.5-10 cm) wide
• Bandage or wrap (eg, Bias bandage or Ace wrap), 2-3 in. (~5-7.5 cm) wide
• Clean room-temperature water in a basin
• Trauma shears or a pair of medical scissors without pointed ends
• Chucks pads and bed sheet
• Tape (if a Bias bandage is used) or bandage clips (if a non-Velcro Ace wrap is used)

For injuries or reductions that require shorter drying times, faster-setting plaster is available (eg, Specialist Extra Fast Setting Plaster, which sets in 2-4 minutes). However, because the plaster dries faster, the risk of thermal injury increases. For most splints, regular plaster (eg, Specialist Fast Setting Plaster, which sets in 5-8 minutes) is appropriate.

Anesthesia

Radial gutter splinting is usually tolerated without the use of anesthesia. However, if significant manipulation or reduction of the injury is required during the splinting process, anesthetic techniques may be used. Acceptable techniques include the following:

• Administration of a hematoma block or nerve block (see  Anesthesia, Regional, Digital Block or  Nerve Block, Radial)
• Procedural sedation with appropriate monitoring and administration by an experienced physician ^[5]
• Administration of oral or intravenous pain medications, including nonsteroidal anti-inflammatory drugs (NSAIDs) or opioid analgesic agents

With the administration of any analgesic agent or the initiation of a formal sedation protocol, care should be taken to avoid oversedation. A complete neurovascular examination should be performed after the splint has been applied.

Positioning

Place the patient in a comfortable position (eg, seated or reclined). Cover the patient with a sheet to avoid splatter from the wet plaster (see the video below).

Completely expose the injured limb. Remove clothing on the proximal extremity, or warn the patient that it may have to be removed with scissors after the splint is placed. Remove the patient’s jewelry. In particular, rings can cause constriction and ischemia of the fingers with delayed swelling of the soft tissues. If unable to remove a ring, try using soap as a lubricant or consider a ring cutter. (See the video below.)

To assist in achieving neutral position of the hand and wrist, some physicians advocate having the patient hold a can or a bandage wrap. Alternatively, the patient can imagine holding a wine glass. With either method, maintain the wrist at 15-25° extension.

Explain the procedure to the patient, including risks and benefits. Obtain informed consent. Position the patient as described previously (see Periprocedural Care, Positioning).

Apply the stockinette. Cut longitudinally at the distal end of the stockinette to allow covering for the second and third digits. Then, cut an adequate hole for the thumb, being careful to avoid constriction of the thumb. The stockinette should be cut so that it is longer than the splint. It should extend 2-3 cm beyond the overlying padding on either end. In turn, the padding should extend 2-3 cm beyond the overlying wet plaster on either end. Together, the stockinette and padding are pulled over the edges of the wet plaster to create smooth edges. (See the video below.)

Place a piece of padding (eg, Webril) between the second and third digits to help prevent skin maceration. Wrap the padding over the stockinette, overlapping each layer by half the width. Allow for extra length. The padding should extend 2-3 cm beyond the overlying plaster on both ends. Leave nails exposed to allow assessment for perfusion. Smooth out creases and avoid wrinkles, unwrapping and rewrapping as necessary. Apply extra padding to the bony prominences of the wrist, the metacarpophalangeal (MCP) joints, and the interphalangeal (IP) joints. (See the video below.)

Measure the plaster of Paris. For an average-sized adult, a radial gutter splint should be eight to 10 layers thick. Use plaster that is 3-4 in. (~7.5-10 cm) wide. After counting the layers, measure the plaster from the second distal IP (DIP) joint to the proximal third of the forearm. Allow roughly 5 mm of extra length on either end; the plaster shrinks when wet. The excess wet plaster on the ends will be folded over to create smooth edges. Measure and mark an opening on the plaster for placement of the thumb through the splint, and cut out the opening. (See the video below.)

If prefabricated fiberglass is used, the stockinette and padding steps can usually be skipped. In this case, follow the manufacturer's recommendations.

Submerge the plaster in clean room-temperature water. Allow all the bubbles to escape. This starts the lamination process of the plaster and allows the layers to bond together. Squeeze out the excess water. Use a milking action with the fingers to strip out the remaining water. Then, lay the plaster on a flat surface or dry towel, and smooth out wrinkles and folds. This allows further bonding of the plaster layers. (See the video below.)

Apply the wet plaster, over the padding, to the lateral or radial surface of the forearm. The plaster should extend from the second DIP joint to the proximal third of the forearm. Fold outward any excess plaster on the ends. The underlying stockinette and padding should then be folded outward on both ends, creating smooth edges. (See the video below.)

Apply the bandage wrap over the wet plaster. Start distally, at the DIP joints of the second and third digits, and wrap proximally. Cut an adequate hole for the thumb. The thumb and the fourth and fifth digits should be left free. Avoid wrapping too tightly. (See the video below.)

While the plaster is still wet, mold the splint into the desired shape. The wrist and hand should be in a neutral position. Extend the wrist 15-25°, abduct the thumb, and flex the MCP joints to 70°. When immobilizing metacarpal neck fractures, flex the MCP joints to 90°. The hand, wrist, and forearm should remain immobile until the splint is dry. Advise the patient that he or she may feel some warmth released from the plaster as it dries. If the heat becomes too intense, unwrap the splint and remove the plaster immediately; thermal burns can occur. (See the video below.)

Once the splint is dry, check for neurovascular function and capillary refill. The median nerve provides sensory function to the palmar side of the thumb, second, third, and lateral half of the fourth digits and, dorsally, to the distal half of the second and third digits and the lateral half of the fourth digit. The ulnar nerve provides sensory function to the palmar and dorsal aspects of the fifth digit and the medial half of the fourth digit. The radial nerve provides sensory function to the dorsal surface of the hand and to the web space between the first and second digits. (See the video below.)

Remember to check motor function as well. Wipe away any plaster that may have dropped onto the patient's skin.

Deliver appropriate aftercare instructions. Instruct the patient to rest, elevate, and ice the injured limb. Emphasize to the patient that if weakness or numbness, color change (pale or bluish), increasing pressure or pain, or spreading redness or streaking develops, he or she should remove the splint and return immediately, or else go to an emergency department (ED).

Instruct the patient to keep the splint clean and dry and to refrain from sticking any items into it. Patients can be tempted to use sticks, pens, or hangers to scratch an itch. Advise the patient that sticking objects into the splint can wrinkle the padding and lead to pressure sores or cause a break in the skin and lead to an unattended infection.

Consider prescribing an antihistamine for itching. However, if the itching persists or worsens, the splint should be reevaluated for complications.

If the patient received any sedation or opioids, advise against driving or alcohol consumption.

Arrange for follow-up with a consultant, usually in 2-7 days, depending on the reason for the splint.

Potential complications of radial gutter splinting include the following:

• Thermal burns ^[6]
• Pressure injuries
• Contact dermatitis
• Ischemia and neuovascular compromise
• Decreased range of motion (ROM) due to immobilization

Patients can expect some warmth as the plaster dries. As more layers of plaster are used, more heat is produced.[7, 8]  If the patient experiences intense heat or any pain, remove the plaster immediately; thermal burns can occur. To minimize the risk, use clean room-temperature water; water that is dirty or too warm accelerates the setting time and increases the heat produced.[8]  Do not wrap towels or blankets around the splint to shorten the drying time; this produces excess heat.

To prevent pressure sores, provide extra padding to bony prominences. When wrapping the cotton padding, avoid creases; if creases do occur, smooth them out or unwrap and rewrap, as needed. When molding the wet plaster, use broad-based pressure. In other words, do not use the fingertips; rather, use the entire palmar surface of the hands and fingers to mold the plaster.

Ischemia and neurovascular compromise may be caused by increased pressure from swelling. If moderate-to-significant swelling is anticipated, cut the cotton padding lengthwise along the medial or ulnar side of the forearm before applying of the wet plaster to the radial side. This allows for expansion of the padding. If using tape to secure the outermost bandage wrap, do not tape circumferentially.

Application of a radial gutter splint can result in compression of the median nerve, which provides sensory function to the palmar side of the thumb and second and third digits and the lateral half of the fourth and, dorsally, to the distal half of the second and third digits and the lateral half of the fourth. Any numbness or weakness in this distribution suggests median nerve compression and should prompt splint removal with subsequent neurovascular examination. Immediate consultation (with orthopedics or hand surgery) should be considered if symptoms do not resolve.

Advise the patient that, depending on the extent and nature of the initial injury, he or she can often expect long-term pain, arthritis, stiffness, and decreased ROM, despite best care practices. Aftercare of such injuries often requires physical therapy.