Ankle Splint – Indications, Contraindications

Ankle Splint is defined as a rigid or flexible device that maintains in position a displaced or movable part; also used to keep in place and protect an injured part or as a rigid or flexible material used to protect, immobilize, or restrict motion in a part.^[rx] Splints can be used for injuries that are not severe enough to immobilize the entire injured structure of the body. For instance, a splint can be used for certain fractures, soft tissue sprains, tendon injuries, or injuries awaiting orthopedic treatment. A splint may be static, not allowing motion, or dynamic, allowing controlled motion. Splints can also be used to relieve pain in damaged joints. Splints are quick and easy to apply and do not require a plastering technique. Splints are often made out of some kind of flexible material and a firm pole-like structure for stability. They often buckle or Velcro together.

Anatomy and Physiology

The ankle’s anatomy can be broken down into osteology, musculature, and neurovascular structures.

The ankle joint is made up of the distal tibia, the distal fibula, and the talus. The distal tibia articulates with the distal fibula to form the distal tibiofibular articulation and the talus, forming the tibiotalar joint. This is an important anatomical distinction as this is the true “ankle” joint. Oftentimes the subtalar joint, which is the articulation between the talus and the calcaneus, is included when discussing the ankle joint; however, this is, technically, not a part of the ankle but, rather, the hindfoot.[rx] The different acute conditions associated with the tibiotalar and subtalar joint make this clinically important.

The distal tibia has three distinct portions: the plafond, the lateral distal tibia, and the medial malleolus. The plafond is the actual weight-bearing portion that articulates with the talus below. The distal physis ossifies around the age of one year and typically fuses around the age of 18 to 20 years. The physis closes in a predictable manner, first centrally, followed by medially, and finally laterally. As a result of this phased closure, there are unique adolescent ankle fractures such as the tillaux fracture and the triplane fracture.[rx] The distal tibia has a concave shape and therefore is congruent with the talar body/dome. The lateral distal tibia serves as an important attachment site for two of the syndesmotic ligaments: the anterior-inferior tibiofibular (AITFL) and posterior-inferior tibiofibular ligaments (PITFL). The AITFL attaches to the tillaux-Chaput tubercle, and the PITFL attaches to the posterior malleolus.[rx] The lateral distal tibia also contains a groove for the fibula called the incisura. The medial malleolus serves as the attachment site for the deltoid ligament, which is composed of a superficial and deep portion. In addition to this, the medial malleolus serves as a bony restraint to the medial translation of the talus within the tibiotalar joint.

The distal fibula, commonly referred to the lateral malleolus at the level of the ankle joint, ossifies around the age of 4 years and fuses around the age of 18 to 20 years. As previously mentioned, it serves as an important attachment site for the two syndesmotic ligaments (AITFL and PITFL). It also serves as an attachment site for the anterior talofibular ligament (ATFL), the posterior talofibular ligament (PTFL), and the calcaneofibular ligament. Avulsion fractures are common due to the multiple ligamentous attachments to the lateral malleolus. The lateral malleolus serves as a bony restraint to the literal translation of the talus within the tibiotalar joint and is important in the stability of the ankle joint.

The talus ossifies around the age of 7 months and fuses around the age of 13 to 15 years. It is composed of a head, neck, body/dome, posterior process, and lateral process. The talus articulates with the navicular, the calcaneus, and the distal tibia. The body is mostly covered with articular cartilage, and the majority of the body weight is transmitted through the dome upon weight-bearing.[rx]

The musculature at the level of the ankle joint tends to be more tendinous, as the bulk of the muscle bellies are more proximal in the leg. As the muscles travel distally, their tendons cross the ankle joint and insert on the bones of the foot. The four compartments in the leg each have their own set of muscles.

Four Leg Compartments

Anterior compartment

• Tibialis anterior
• Extensor hallucis longus
• Extensor digitorum longus
• Peroneus tertius

Lateral compartment

• Peroneus longus
• Peroneus brevis

Superficial posterior compartment

• Gastrocnemius
• Soleus
• Plantaris

Deep posterior compartment

• Popliteus
• Flexor hallucis longus
• Flexor digitorum longus
• Tibialis posterior

Types of Ankle Splint 

• Ankle stirrup – Used for the ankles.
• Finger splints – Used for the fingers. A “mallet” or baseball finger is a rupture of the extensor tendon and sometimes including a fracture. While surgery may be necessary such an injury may heal if placed in a finger splint.^[
• Nasal splint
• Posterior lower leg
• Posterior full leg
• Posterior elbow
• Sugar tong – Used for the forearm or wrist. They are named “sugar-tong” due to their long, U-shaped characteristics, similar to a type of utensil used to pick up sugar cubes.
• Thumb spica – Used for the thumb.
• Ulnar gutter – Used for the forearm to the palm.
• Volar wrist splint – Used for the wrist.
• Wrist/arm splint – Used for the wrist or arm.

Indications of Ankle Splint

Indications for ankle splinting

• Lateral malleolus fracture
• Medial malleolus fracture
• Posterior malleolus fracture
• Bimalleolar fracture
• Trimalleolar fracture
• Tibiotalar dislocation or subluxation
• Ankle fracture-dislocation
• Temporary stabilization of acute fractures, sprains, or strains before further evaluation or definitive operative management
• Immobilization of a suspected occult fracture (such as a scaphoid fracture)
• Severe soft tissue injuries requiring immobilization and protection from further injury
• Definitive management of specific stable fracture patterns
• Peripheral neuropathy requiring extremity protection
• Partial immobilization for minor soft tissue injuries
• Treatment of joint instability, including dislocation

Contraindications of Ankle Splint

• Situations in which caution must be exercised include the presence of thermal or electrical burns, open fractures, grossly contaminated wounds, and significant soft tissue swelling.
• Injuries that violate the skin or open wounds. Antibiotic administration should be considered for these patients depending on the severity of the lesion.[rx] These patients also require additional soft tissue care, which may necessitate tissue debridement and skin closure before splint application.
• Injuries that result in sensory or neurologic deficits. The complications of splint placement such as compartment syndrome, pressure injuries, or malreduction may go unnoticed if the patient has a concurrent nerve injury. These patients should undergo evaluation by a surgeon before splint application as neurologic findings may be a sign of a surgical emergency.
• Injuries to the vasculature require special attention by vascular surgeons, as these may require urgent operative intervention. Furthermore, evaluation of the vasculature is essential both before and after splint application, as the reduction of some fractures may result in acute arterial injury or obstruction if trapped between the fracture fragments.
• Patients with peripheral vascular disease or neuropathy. Special care should be taken when applying lower extremity splints in these patients since their baseline sensation may be altered. These patients have difficulty detecting pressure sores, skin irritation, and possible vascular compromise.

Equipment of Ankle Splint

• Stockinette
• Cast padding
• Plaster splinting material
• Water; cold water maximizes molding time, warmer water facilitates hardening
• Elastic bandages
• Sheet or towel to protect patient clothing
• Stockinette (a soft, loosely knitted stretch fabric) or fabric underpadding
• Undercast padding, which is typically made out of cotton.
• Plaster (8-10 sheets thick) or padded fiberglass. In general, forearm splints require smaller width, and upper arm and leg splints require larger width rolls of material.
• Water bucket filled with cool water.
• Elastic bandage
• Sling for upper extremity injuries
• If fracture reduction is attempted, a C-arm X-ray should be used for the evaluation of the fracture reduction.

Personnel

Depending on the application, ankle splinting may be done alone or may require an assistant.

• If the patient can follow direction and there is no dislocation or subluxation of the ankle joint, an assistant may not be necessary.
• If the ankle requires a reduction, an assistant will be necessary to hold the ankle during splint application. Furthermore, if the patient is not cooperative or is sedated, an assistant will be required to hold the leg.

Preparation

There are three main splinting options for the ankle. The most stable splint is the stirrup plus posterior slap splint. This is the most ideal splint for bimalleolar, trimalleolar, or ankle fracture-dislocations. The other options include a stirrup splint or a posterior slab splint. These two splints do not provide sufficient stability for anything other than an isolated medial, lateral, or posterior malleolar fracture. The posterior slab provides stability in the antero-posterior direction as well as preventing ankle dorsiflexion and plantarflexion. The stirrup wraps around the medial and lateral malleoli providing medial-lateral stability.

It is important to determine the length of the plaster required for splinting before beginning. For patient comfort, the uninjured leg may be used as a substitute to measure length. The length of the posterior slab should begin just distal to the metatarsal heads and end below the popliteal fossa. It is important that the posterior slab is not too long as this can cause skin irritation and breakdown in the popliteal fossa especially as the knee is flexed. The stirrup portion wraps from the medial aspect of the leg, around the heel, and up the lateral aspect of the leg. It should begin around the proximal third of the tibia medially and below the fibular head laterally. Plaster needs to be at least eight sheets thick to provide adequate strength but no more than 12 sheets thick to avoid thermal injury. Plaster produces heat as it hardens, and care must be taken to prevent thermal injury.

Before splint application, any fracture-dislocation should be reduced. Stockinette is cut to cover the leg so that there is extra past the toes and past the knee.  The extra stockinette will be folded down over the plaster which allows the creation of padded cuffs at the ends of the splint for patient comfort. Cast padding is used to wrap directly over the stockinette, beginning from the metatarsal heads and continuing all of the way up the tibial tubercle. Care must be taken to sufficiently pad the medial and lateral malleoli and heel to prevent pressure ulcers from developing in the splint. The plaster splinting material for the posterior mold is wet, wrung, bonded, and placed on the plantar aspect of the foot, extending up to below the popliteal fossa. Cast padding may be used to wrap over the plaster to hold it in place while the remainder of the plaster is applied. The plaster splinting material for the stirrup is wet, wrung, bonded and placed starting on the medial aspect of the leg, wrapping around the plantar aspect of the heel and up the lateral aspect of the leg. Cast padding may be used to wrap over the plaster splinting material once more, and the excess stockinette at the ends of the splint may be folded down to produce a cuff. An elastic bandage is used to wrap over the splint. Once wrapped with the elastic bandage, molding may begin. Molding is necessary for ankle dislocations or subluxations to produce a buttress to keep the ankle joint reduced. It is also important to ensure that the ankle joint is in neutral dorsiflexion. Splinting the ankle in a plantarflexed position will result in an equinus contracture of the heel cord.

Technique

• Measure the appropriate length of plaster, 8 to 12 sheets thick for the posterior slab, and stirrup.
• Measure and cut stockinet for the leg.
• Perform reduction of the ankle, if necessary. Have an assistant hold leg and ankle to maintain reduction during splinting.
• Place stockinette on the leg.
• Wrap leg with cotton rap beginning at the metatarsal heads and ending at the tibial tubercle, ensuring 50% overlap of padding with a minimum of two layers. Ensure that the medial and lateral malleoli and heel are well padded. Attempt to avoid bunching or wrinkles in padding.
• Dip plaster into the water to thoroughly wet.
• Wring wet plaster and bond together between fingers.
• Apply posterior slab over cotton wrap on the leg, ensuring that the plaster begins at the plantar aspect of the metatarsal heads and ends below the popliteal fossa.
• Apply stirrup over cotton rap on the leg, ensuring that the plaster begins around the proximal third of the tibia medially, wrapping around the heel, and up the lateral aspect of the leg ending below the fibular head.
• Overwrap plaster with one layer of cotton wrap to keep plaster from sticking to the elastic bandage.
• Fold excess stockinette over plaster and wrap so that there is a cuff at each end of the splint.
• Loosely wrap entire splint with an elastic bandage.
• Apply appropriate mold while the plaster is hardening. Ensure that the ankle is in neutral dorsiflexion.
• Avoid placing the splint on pillows or a blanket as this has an insulating effect.
• Once splint is hard, re-assess the neurovascular status of the foot and toes.

General steps may be applied when placing a splint

• Ensure adequate analgesia before splint application. This will ensure muscle relaxation and facilitate fracture reduction, if necessary.
• Ensure that any soft-tissue injuries are addressed before splint placement.
• Apply a stockinette circumferentially to the injured area. This should span both proximally and distal to the injured area, protecting the skin from irritation by the plaster or fiberglass.
• Pad bony prominences such as the elbow, knee, or calcaneus with at least 1 cm to 2 cm of soft cast padding. Soft tissue protection is essential to prevent future skin irritation or necrosis. The thickness of this padding will depend on body habitus.
• Apply 2-3 layers of cast padding (0.25 cm to 0.5 cm) circumferentially to the remaining area of immobilization.
• Reduce any fracture by restoring the bone length, rotation, and alignment. This may require radiographic confirmation before support material application.
• Activate the supportive plaster or fiberglass layers by saturating them in the water bucket. Laminate the sheets by pressing them together before application, as this increases the strength and adhesion between the layers.
• Mold the supportive material around the area of injury. The specific molding approach will depend on the type of injury; however, as a general rule, the splint should be molded to resist any deforming angulation.
• Ensure the supportive material does not circumferentially encase the injured area to accommodate any soft-tissue swelling. If there is circumferential overlap, this should be addressed by cutting the splint once the supportive material has set.
• Fold the stockinette over the plaster or fiberglass to protect the patient’s skin from its sharp edges.
• Circumferentially apply an elastic bandage around the splint. This aids in the molding of the splint material to the injured area and holds the support material in place until it has hardened. Direct placement on the skin should be avoided and is a commonly observed mistake.[rx]
• Repeat the physical exam to ensure that there is no significant change in the patient’s neurovascular status. Any change in the physical exam should prompt the rapid removal of the splint and reassessment.
• Counsel the patient on proper splint care and follow-up instructions.
• Coaptation splint, sugar tong splint, posterior long arm elbow splint, ulnar gutter splint, radial gutter splint, volar or dorsal short arm splint, thumb spica splint
• Posterior long leg splint, posterior short leg splint, posterior short leg splint with stirrups

These specific splinting approaches are well described elsewhere.[rx]

Complications

• Pressure necrosis – can begin as soon as 2 hours after splint application, resulting from inadequate padding of bony prominences
• Compartment syndrome – if splint wrapped too tightly
• Thermal injury – if plaster too thick or if inadequate padding
• Equinus contracture – if splint applied with the ankle in plantarflexion
• Joint stiffness – Every effort should be made to immobilize the fewest number of joints possible.
• Thermal injury – Both plaster and fiberglass support materials exhibit exothermic reactions when activated by water. Avoid skin burns by using room-temperature water when activating the support material and through careful monitoring after splint placement.
• Neurovascular compromise – Acute carpal tunnel syndrome is a rare complication following the reduction of a wrist dislocation. Similarly, the reduction of a supracondylar humerus fracture may inadvertently occlude the brachial artery. Both scenarios are exacerbated through splint placement and require prompt splint removal, followed by a possible operative intervention.
• Compartment syndrome – Excessive compression may occur through splint placement, mainly if a splint is circumferential, becoming a cast.
• Loss of fracture reduction
• Skin irritation or breakdown

References