Triplane Fracture

Triplane fracture of the ankle involves the bony structures and their associated ligamentous supports (see the image below).

Triplane fracture involves the tibial metaphysis, tibial growth plate (physis), and the epiphysis. This image depicts each of the involved anatomic areas. It is important to recall the structural lines of development and maturation of the metaphysis, physis, and epiphysis, as they relate to the triplane fracture. Note that forces transmitted to the physis and epiphysis create fracture lines consistent with the maturity of these structures. For an unfused growth plate, separation is likely to occur here. When the growth plate is fused (closed), the avulsed portion is likely the most recent portion of the growth plate that has fused. This part represents the weakest (least calcified and least matured) portion of the physis. Frequently this involves the anterolateral growth plate.

The tibia is the main weightbearing bone of the lower leg. The tibial metaphysis consists of the distal quarter of the tibia, excluding the tibial growth plate and epiphysis.

The distal tibial physis, also called the growth plate, is located between the tibial metaphysis and the epiphysis. The distal tibial epiphysis is bordered proximally by the physeal growth plate and distally by its articulation with the articular surface of the talar dome. It contributes 50% of tibial growth and approximately 4-6 mm (0.25 in.) of longitudinal growth per year.[9, 10]

The fibula is situated laterally along the length of the tibia in the lower leg, giving stability to the lateral ankle joint and serving in a nonweightbearing role.

The ankle joint bears more weight per unit of surface area than any other joint in the body. The ankle joint is formed by the fibula (laterally), the tibia (superiorly and medially), and the dome of the talus (inferiorly). The joint is saddle-shaped. The dome of the talus becomes wider anteriorly, such that when the foot is in dorsiflexion, the talus is situated more snugly in the tibiofibular saddle than when the foot is plantarflexed. Thus, plantarflexion (a position contributing to the triplane fracture) is a less stable position of the ankle than is dorsiflexion.

The only pure motions of the ankle joint are dorsiflexion and plantarflexion. Inversion and eversion of the ankle joint take place at the subtalar joint formed by the opposition of the talus and the inferiorly situated calcaneus. The talus always moves in the same direction as the calcaneus in normal gait.

Ankle injuries typically follow forces that are directed perpendicularly (inversion or eversion) to the normal motion of the ankle. That motion is perpendicular to the motions of dorsiflexion and plantarflexion that occur in the sagittal plane.

Ligamentous support of the ankle is extensive. Ligaments situated laterally consist of anterior and posterior talofibular and tibiofibular ligaments. The strong deltoid ligament is located medially and is the only ligament of the ankle containing elastic fibers.

The tibia and fibula are joined by the anterior and posterior talofibular ligaments distally and the interosseous membrane more proximally.

Knowledge of the anatomic planes of the body is essential to understanding the lines, planes, and fragments produced in a triplane fracture. In the anatomic position (ie, with the person standing, palms forward), these two-dimensional (2D) planes are as follows:

• The horizontal plane passes horizontally through the body, dividing it into upper and lower segments
• The coronal plane passes through the body from one shoulder to the other, dividing it into front and back segments
• The sagittal plane passes through the body from front to back, dividing it into right and left segments

Motions of the ankle and foot are described by a number of interchangeable terms, including the following:

• Eversion - External rotation
• Inversion - Internal rotation
• Dorsiflexion - Extension
• Plantarflexion - Flexion
• Abduction - Lateral deviation of the foot on a longitudinal axis through the tibia
• Adduction - Medial deviation of the foot on a longitudinal axis through the tibia
• Supination - Adduction and inversion
• Pronation - Abduction and eversion

Neurovascular structures in the area of the ankle and foot include the following:

• Medially, both the posterior tibial artery and tibial nerve pass deep to the flexor retinaculum spanning between the distal tibia and the calcaneus
• Arterial pulses of the foot and ankle should be checked in any injury to the region and are readily palpable over the posterior tibial artery area medially and the dorsalis pedis artery on the dorsum of the foot between the bases of first and second metatarsals

Triplane fracture of the distal tibia rarely occurs outside of adolescence. This is directly related to the pattern of distal tibial growth plate closure as skeletal maturity is attained (see the image below).

(A) The distal tibial growth plate begins to close with a centrally located epiphyseal hump and proceeds medially, with posterior closure occurring before anterior closure. Following medial closure, the lateral tibial growth plate then closes progressively from the posteromedial area (B) to the anterolateral area (C, D). The entire process of physeal closure usually spans a period of 18 months. This process generally occurs when the individual is aged 12-15 years (mean age is 13.5 years, age range is 10-18 years), with complete closure occurring earlier in girls than in boys.

The distal tibial epiphysis begins to close with a centrally located epiphyseal hump and proceeds medially, with posterior closure occurring before anterior closure. Adolescent children are susceptible to a triplane fracture after medial physeal closure and before lateral physeal closure. After medial closure, the lateral tibial growth plate closes progressively from the posteromedial area to the anterolateral area. The anteromedial tibial growth plate is the last area to close; therefore, it is more prone to injury than any other area of the tibial growth plate.

The entire process of distal tibial growth plate closure (physiologic epiphysiodesis) usually spans a period of 18 months. This process generally occurs when the individual is aged 12-15 years (mean, 13.5 years), with complete closure occurring earlier in girls than in boys.

Regardless of the age of the patient, it is important to remember that variation (age range, 10-18 years) exists around the mean age of expected closure of the tibial growth plate. Any time the lateral distal tibial growth plate is open (unfused), the patient is susceptible to a triplane fracture.

As previously described, a triplane fracture involves fracture lines in the sagittal, coronal, and transverse planes; however, there are three types of triplane fractures, as follows:

• Two-part triplane fractures
• Three-part triplane fractures
• Four-part triplane fractures

Each type may have a coexisting fibular fracture as well, but this is not counted as a component of the triplane fracture; only tibial fragments are counted as such. Other rare and unusual variants of the two- and three-part triplane fractures have been reported, such as the medial triplane fracture described by Denton and the triplane fracture shown in the images below.[11]

Lateral radiograph of a triplane fracture illustrates the following: Yellow arrows indicate the horizontal component of the fracture through the physis (growth plate), red arrows indicate the vertical fracture line in the coronal plane involving the metaphyseal spike complex, black arrows point to the posterior margin of the metaphyseal spike, and purple arrows indicate the associated fibular fracture. This image represents one of the first known published images of this type of 2-part triplane fracture.

Radiograph of a triplane fracture. The anterior-posterior view of the distal tibia and epiphysis is illustrated as follows: Yellow arrows indicate the horizontal fracture component through the growth plate, white arrows indicate the vertical fracture through the epiphysis in the sagittal plane, and black arrows outline the superior edges of the posterior metaphyseal spike. An associated fibula fracture is present. In this left-sided 2-part triplane fracture, medial is to the viewer's left, and lateral is to the right. This image represents one of the first known published images of this type of 2-part triplane fracture.

Digital 3-dimensional helical CT scan reconstruction of a rare type of triplane fracture. The image shown is of the inferior surface of the tibial epiphysis. Medially (viewer's left) is the distal tibial malleolus. Laterally (viewer's right) is the distal fibula/lateral malleolus. Fracture lines exist through the tibial epiphysis in the coronal, sagittal, and horizontal planes. The posterolateral fragment of the epiphysis is attached to the posterior metaphyseal spike rather than the more common anterolateral segment of the epiphysis. This image represents one of the first known published images of this type of 2-part triplane fracture.

Two-dimensional helical CT scan image prior to 3-dimensional reconstruction. PLEF represents the posterolateral epiphyseal fragment. DF is the distal fibula. The posteromedial and the entire portion of the anterior epiphysis are intact. This image represents one of the first known published images of this type of 2-part triplane fracture.

In a two-part triplane fracture (see the image below), the first fracture line in the transverse (horizontal) plane is through the tibial epiphysis, leaving the anteromedial portion of the epiphysis attached to the distal tibia. The second fracture line is in the sagittal plane through the epiphysis, lateral to the original formation of the epiphyseal fusion hump. The third fracture line is in the coronal plane and courses superiorly through the posterior metaphysis, producing a posterior metaphyseal spike. The following two fragments result:

• Lateral portion of the epiphysis attached to a posterior metaphyseal spike
• Distal tibia with the anteromedial epiphysis attached

In a 2-part triplane fracture, 3 fracture lines are identified in each of the transverse, coronal, and sagittal planes. The first fracture line in the transverse (horizontal) plane is through the growth plate (physis), leaving the anteromedial portion of the physis attached to the distal tibia. The second fracture line is in the sagittal (anteroposterior) plane through the epiphysis, lateral to the original formation of the epiphyseal fusion hump. The third fracture line is in the coronal plane and courses superiorly through the posterior metaphysis, producing a posterior metaphyseal spike. The resulting 2 fragments are (1) a fragment consisting of the posteromedial and lateral portions of the epiphysis attached to a posterior metaphyseal spike and (2) the distal tibia, with the anteromedial epiphysis attached.

In a three-part triplane fracture (see the image below), three fracture lines again are present in each of the three anatomic planes; however, the fracture line in the coronal plane is complete in its course through the epiphysis, as well as through the posterior metaphysis. The following three fracture fragments are produced:

• Rectangular fragment of the anterolateral portion of the epiphysis
• Remainder of the epiphysis with an attached posterior spike of the distal tibial metaphysis
• Tibial shaft with the anteromedial epiphysis

In a 3-part triplane fracture, the 3 fracture lines are present in each of the 3 anatomic planes; however, the fracture line in the coronal plane is complete in its course through the epiphysis and posterior metaphysis. The 3 fracture fragments thus produced are (1) a rectangular fragment of the anterolateral portion of the epiphysis, (2) the remainder of the epiphysis with an attached posterior spike of the distal tibial metaphysis, and (3) the tibial shaft with the proximal metaphysis and anteromedial epiphysis.

The four-part triplane fracture is similar to the three-part fracture, with the exception that the fourth fragment consists of the medial malleolus. This is a result of the extension of the fracture forces projecting more medially in the horizontal plane.

Shin et al classified a subtype of triplane fractures in which the fracture extended into the medial malleolus.[12] Using three-dimensional (3D) computed tomography (CT), they delineated the intramalleolar fracture patterns and demonstrated three distinct types of intramalleolar triplane fractures, as follows:

• Intra-articular and within the weightbearing zone
• Intra-articular and outside the weightbearing zone
• Extra-articular

A quadriplane fracture (ie, a typical triplane fracture plus a metaphyseal fragment) has been described. A combination of external rotation and vertical compression has been proposed as the mechanism of injury.[13]

Kleiger and Mankin described an elevation or hump in the growth plate, about 1 cm from its medial edge, in 40% of adolescents between the ages of 12 and 20 years. They suggested that the medial hump might prevent displacement of the medial part of the epiphysis by a rotational force.[14] This was corroborated by Clement and Worlock, who suggested that the medial hump may stabilize the anteromedial part of the epiphysis in the same way as fusion of the medial part of the plate in older children.[15]

Dias and Giegerich suggested that two grades of injury can result from a lateral or external rotation force applied to the distal tibia during the period of growth plate fusion. In a grade I injury, the anterior tibiofibular ligament avulses the anterolateral corner of the distal tibial epiphysis (the juvenile Tillaux fracture). The Tillaux fracture fragment in adults is virtually identical to the anterolateral epiphyseal fragment in a triplane fracture. If there is further lateral or external rotation, the remainder of the distal tibial epiphysis separates through the growth plate, taking with it an attached posteromedial metaphyseal fragment and producing a grade II three-part triplane fracture.[16]

Yung et al performed a retrospective study of all triplane fractures identified from 2012 to 2016 in a tertiary referral center, looking for atypical triplane fractures; 10 atypical fracture patterns were identified.[17] ​ Atypical triplane fractures are defined as triplane fractures that are intra-articular but affect the nonweightbearing area of the tibia plafond or extra-articular triplane fractures in which the epiphyseal fracture line exits outside the articulating cortex of the medial malleolus. The authors identified a new extra-articular triplane fracture variant with an anteromedial epiphyseal sleeve fragment.

Triplane fracture is the result of several factors that exist simultaneously, including the following:

• A partially open distal lateral tibial growth plate, which creates a plane of weakness when a shearing force is applied; this condition is found most commonly during adolescence
• External rotation (eversion) of the foot on the tibia (horizontal plane influence), which creates stress along the open distal lateral tibial growth plate, and is the essential force that initiates a triplane fracture
• Exact fracture lines that are propagated further through the coronal and sagittal planes as a result of the foot being in plantarflexion (most common) and the varying forces of axial loading

Triplane fracture occurs most commonly in patients aged 12-15 years. It represents 5-10% of all pediatric intra-articular ankle injuries.

The male-to-female frequency ratio has ranged from 1:1 to 2:1 in the literature. In studies indicating a higher incidence in males, this is postulated to be caused by later closure of the lateral tibial growth plate in males than in females, thereby lengthening the period of vulnerability to injury for males.

A higher incidence in the right ankle is reported most often. However, one report noted a preponderance in the left ankle.[18]

Two-part triplane fractures occur more commonly and at a younger age than three-part triplane fractures. This reflects the fact that relatively less closure of the tibial epiphysis exists in the three-part group than in the two-part group.

Missed or incompletely diagnosed triplane fractures initially were evaluated with plain film radiography without further CT studies.

Of the 8683 childhood and adolescent fractures evaluated by Landin over a 9-year study period, 4% (373) were ankle fractures.[19]  More than 50% of ankle injuries were sustained during a fall. Right-side injury predominated almost 2:1. Seasonally, over the 9-year study period, peak incidence was in April and September, with the lowest frequency in July and December.

In this study, males sustained more ankle fractures than did females.[19] For males, the incidence for each of the 2-year age groups studied was highest for those aged 15-16 years. For females, incidence was highest for those aged 13-14 years. During the study period, the incidence of ankle injuries progressively increased. This may reflect the increasing popularity of roller skates, skateboards, and scooters.

Devalentine found upon review of 118 epiphyseal injuries in childhood that 25% involved the distal tibial or fibular epiphyses.[20]  MacNealy studied 194 cases of injuries of the distal tibial epiphysis and reported that 9.8% were triplane fractures.[21]  The fibula is fractured in approximately 50% of triplane fractures.[22, 23, 24]

Although other associated injuries are uncommon, ipsilateral tibial shaft fractures[25] and a Maisonneuve fracture[2] associated with a triplane ankle fracture have been described.

Sheffer et al conducted a study to establish the frequency of concurrent ipsilateral distal tibial fractures with tibial shaft fractures in the pediatric population; to identify patient and fracture characteristics that increase the likelihood of a concurrent fracture; and to determine if any of these concurrent distal tibial fractures were missed on initial radiographic examination.[26] A retrospective chart review identified 515 patients 5-17 years old who were treated for 517 tibial shaft fractures at a large level 1 freestanding children's hospital and an outpatient orthopedic practice between 2008 and 2016.

Of the 517 fractures, 22 (4.3%) were associated with concurrent ipsilateral distal tibial fractures, including 11 triplane fractures.[26] Patients with concurrent fractures were older than those with isolated tibial shaft fractures (12.7 vs 11 years). Patients with a tibial shaft fracture at the junction of the middle and distal thirds were significantly more likely to have a concurrent distal tibial fracture; oblique and spiral fracture patterns were more frequent in the group with concurrent distal tibial fractures. That 36% of the concurrent distal tibial fractures were not diagnosed until chart review for this study was undertaken suggested the need for ankle-specific imaging in certain patients.

The outcome and long-term prognosis for individuals with triplane fracture are related primarily to concerns in the following two areas:

• Posttraumatic arthritis - When fracture fragment reduction (either closed or open) is inadequate, the long-term prognosis is less than favorable; posttraumatic arthritis may take years to be appreciated fully; studies support the contention that the development of posttraumatic arthritis is related primarily to inadequate realignment of the inferior surface of the epiphysis as it articulates with the talar dome
• Tibial length growth retardation secondary to epiphyseal growth plate injury - This is a lesser concern, in that most triplane fractures in adolescents occur at a time when at least medial growth plate closure has occurred, leaving only the lateral growth plate open

Intraoperatively, it is important not to place compression screws or other hardware that exert compression forces on the growth plate. Such compression exacerbates premature growth plate closure and tibial growth retardation. Also, any physeal gaps lead to bony bridge formation and therefore require perfect reduction.

Rotational malalignment, which most often manifests as external rotation deformity, will adversely affect the foot progression angle.[27]

Postoperative infection and osteomyelitis are uncommon complications. Either may be attributed to a lack of patient cleanliness and compliance or to poor surgical technique, or may result from a highly contaminated open fracture.

Pressure injuries may result from localized swelling, a cast that gets wet and expands, or a cast that is fitted improperly. In all such cases, the patient develops point tenderness that was not present previously under the cast. Remove the cast, and inspect and palpate the entire area to identify the location and cause of the pain.

If the pain is caused by pressure alone, a new cast is applied with extra padding in the area of pain and attention to avoiding all pressure to the area. If skin breakdown is noted, standard wound therapy, which may include oral antibiotics, should be initiated. The cast is reapplied as above, with the addition of a cast window. This allows ongoing wound checks and dressing changes until the wound resolves, while avoiding frequent cast changes for wound care.

Fracture blisters are caused by blood accumulating under the skin in an area of swelling that accompanies a fracture. This can result in skin breakdown and ulceration. Care of fracture blisters is similar to that for pressure injuries. It is imperative that no surgical therapy for the fracture, initial or delayed, should be attempted at a site with fracture blisters, because of the high risk of wound complications in the affected area.

Compartment syndrome may affect any of the four compartments of the lower leg or the deep plantar compartment of the foot. This may manifest as pain or burning, which may be severe at rest or with passive dorsiflexion of the foot. Sensation is affected first, then motor function.

Commonly, the anterior tibial compartment is affected with resultant increasing compartment pressure on the superficial peroneal nerve, which results in heightened pain on passive motion of the toes followed by decreased sensation in the first and second web spaces of the toes. The foot or lower leg may be tense and hard. Findings should be compared with those of the unaffected limb. If compartment syndrome is confirmed by measurement of compartment pressures, immediate operative intervention is required.

An accurate account recreating the action that led to the injury assists the practitioner in predicting the area of injury. In a triplane fracture of the ankle, nearly all cases involve an external rotation of the foot on the tibia, creating stress along the distal lateral open tibial growth plate. Other contributing forces that propagate the fracture lines are axial loading in combination with the foot being in plantarflexion (most common) and supination, abduction, or pronation.

Patients are more likely to be adolescent males with right-side ankle injuries.

It is important to inquire about other areas of injury or pain. The pain of a triplane fracture is sufficient to distract attention from other areas, even when a significant injury is present.

Other chronic medical conditions (eg, prior injury or surgery; orthopedic hardware in the area of injury; diabetes; peripheral vascular disease; metabolic bone disease) should be documented.

Current and recent use of medications, including corticosteroids, should be determined.

Patients with a triplane fracture of the ankle present with the following:

• Pain
• Swelling
• Possible ecchymosis
• Possible ankle deformity
• Inability to bear weight on the injured ankle

All areas should be observed for evidence of open injury, including lacerations and abrasions. The patient should be asked to demonstrate any ankle and toe motion that can be performed voluntarily without assistance.

Posterior tibial and dorsalis pedis pulses should be checked and compared with the pulses on the uninjured side. Up to 15% of the population has a congenital absence of the dorsalis pedis artery. Adequate distal capillary artery refill—that is, 2 seconds or less—should be checked for.

The patient should be assessed for distal sensation and evidence of compartment syndrome tingling, decreased sensation, swelling, pale skin, diminished pulses, and severe pain with passive movement of the toes.

The knee, the leg, and the foot should be examined for tenderness, ecchymosis, and swelling. Radiographs of the knee, the leg, and the foot are needed if there are positive findings. Careful attention must be paid to the fibula, which must also be palpated and inspected along its entire length. Fibular fractures are commonly associated with triplane fractures. A fibular fracture likely to be missed upon initial evaluation is the Maisonneuve fracture of the proximal fibula, as reported by Healy.[25]

Other areas at high risk for fracture, such as the calcaneus and the proximal fifth metatarsal, should be inspected and palpated. The calcaneus should be cupped as if it were a tennis ball and gently compressed. If pain is elicited, a calcaneal fracture should be suspected.

Early discussions of distal tibial fractures occurring in adolescence lacked consistent and exact descriptions of the fracture fragments because plain radiographs were used to visualize and characterize the fragments. Additionally, involvement of the tibial growth plate in these fractures was suspected but not understood completely.

The advent of computed tomography (CT) and magnetic resonance imaging (MRI) made it possible to delineate the exact anatomy, fracture lines, plane analysis, and other characteristics of the triplane fracture. In particular, any disruption that occurs at the growth plate, the anterior talofibular and tibiofibular ligament, and the talotibial articular plafond is visualized on CT.

The laboratory studies performed in patients with triplane fractures depend on the age of the patient, the extent of all injuries, and other comorbid conditions. Triplane fractures most commonly occur in healthy adolescents. Reasonable, though not mandatory, preoperative studies include the following:

• Complete blood count (CBC)
• Sequential multiple analysis (SMA7)
• Urinalysis
• Blood type and screen

Plain radiography

Ankle (distal tibia, fibula, and talus)

If the patient demonstrates localized pain, inability to fully bear weight, ankle deformity, confounding variables (eg, patient age < 18 years), underlying neurologic deficits affecting the lower limbs, altered mental status, and/or multisystem trauma, or if the patient otherwise meets the Ottawa rules indicating that radiologic evaluation should be performed, anteroposterior (AP), lateral, and ankle mortise views should be obtained with the foot in 15° of internal rotation.

The saddle or headset sign should be observed. The saddle (or telephone headset), consisting of the tibia and fibula, should lie congruently above and around the talus (the horse or the telephone base).

The space between the talar dome and a curved line running along the internal surfaces of the distal tibia and fibula (ankle mortise space) should be equal throughout its length. Lack of symmetry suggests ankle mortise disruption due to ligamentous injury or bony fracture.

Foot

Indications for radiologic studies of the foot include localized pain, deformity, and the inability to bear weight completely. AP and lateral foot films should be obtained. Attention should be directed toward areas at high risk for associated injuries (eg, proximal fifth metatarsal, navicular, cuboid, medial cuneiform, calcaneal bones).

Fibula and tibia

Triplane and other ankle fractures are frequently associated with fibula fractures (see the images below). As a result, forces are transmitted to the fibula in a lateral, medial, or spiral (twisting) motion. Spiral stresses, in particular, may result in a Maisonneuve fracture of the proximal fibula. These are easily missed if the knee and proximal fibula are not examined at the time the ankle and foot are examined.

Lateral radiograph of a triplane fracture illustrates the following: Yellow arrows indicate the horizontal component of the fracture through the physis (growth plate), red arrows indicate the vertical fracture line in the coronal plane involving the metaphyseal spike complex, black arrows point to the posterior margin of the metaphyseal spike, and purple arrows indicate the associated fibular fracture. This image represents one of the first known published images of this type of 2-part triplane fracture.

Radiograph of a triplane fracture. The anterior-posterior view of the distal tibia and epiphysis is illustrated as follows: Yellow arrows indicate the horizontal fracture component through the growth plate, white arrows indicate the vertical fracture through the epiphysis in the sagittal plane, and black arrows outline the superior edges of the posterior metaphyseal spike. An associated fibula fracture is present. In this left-sided 2-part triplane fracture, medial is to the viewer's left, and lateral is to the right. This image represents one of the first known published images of this type of 2-part triplane fracture.

If pain or tenderness is present anywhere along the length of the fibula, radiographs of the fibula should be obtained. This applies equally to any area of the tibia not apparently associated with the primary area of injury.

Other radiographs obtained in anticipation of the operating room depend on the age of the patient, the extent of all injuries, and other comorbid conditions. Triplane fractures most commonly occur in healthy adolescents. Chest radiography is a reasonable, but not mandatory, preoperative study.

Stress radiography

These images may be obtained when plain film evaluation reveals no obvious fractures. Preferably, these radiographs are obtained following orthopedic consultation; stress films lend little to the management of ankle injuries by emergency department physicians.

CT is not indicated for routine evaluation of common ankle fractures, but it is required to assess complex multipart or multiplane fractures of the ankle.[28, 29]  CT demonstrates fracture lines, fracture segments, and intra-articular extent and enables accurate measurement of displacement. If surgery is being contemplated, CT helps with planning the surgical incisions and the direction and orientation of implants (eg, screws) for internal fixation.

In a study designed to assess the utility of radiography, with or without CT, for fracture classification, displacement measurement, and treatment planning in children with triplane fractures, Eismann et al found that the addition of CT had a definite positive impact with respect to all three parameters, which suggested that this modality is a potentially valuable adjunct to radiography in the management of pediatric triplane fractures.[30]

With the advent and greater use of spiral (helical) CT (see the images below) and ultrafast CT scans, as well as the declining costs of this technology, these scans will likely become the imaging modalities of choice for complex multipart and triplane ankle fractures. These scans will also guide approaches to further open intraoperative intervention.

Digital 3-dimensional helical CT scan reconstruction of a rare type of triplane fracture. The image shown is of the inferior surface of the tibial epiphysis. Medially (viewer's left) is the distal tibial malleolus. Laterally (viewer's right) is the distal fibula/lateral malleolus. Fracture lines exist through the tibial epiphysis in the coronal, sagittal, and horizontal planes. The posterolateral fragment of the epiphysis is attached to the posterior metaphyseal spike rather than the more common anterolateral segment of the epiphysis. This image represents one of the first known published images of this type of 2-part triplane fracture.

Two-dimensional helical CT scan image prior to 3-dimensional reconstruction. PLEF represents the posterolateral epiphyseal fragment. DF is the distal fibula. The posteromedial and the entire portion of the anterior epiphysis are intact. This image represents one of the first known published images of this type of 2-part triplane fracture.

Park et al used MRI to investigated the incidence and location of periosteal entrapment in 50 adolescent distal tibial physeal fractures (15 Salter-Harris [SH] type II, 12 type III [four malleolar, eight Tillaux], and 23 type IV [two malleolar, 21 triplane]) and the angle of the fracture plane of metaphyseal fragments on the axial plane.[31]

In all, 36 (72.0%) of the fractures presented with periosteal entrapment.[31] In all type II and triplane fractures, periosteal entrapment was observed in the anterolateral corner when there was any displacement on that corner, whereas only one Tillaux fracture presented with periosteal entrapment. In almost all supinated foot injuries of type II and triplane fractures, the metaphyseal fracture line was parallel to the intermalleolar axis on the axial plane.

The authors concluded that SH type II and triplane fractures have a high risk of periosteal entrapment, especially in the anterolateral corner.[31] Therefore, even without preoperative MRI, surgical repositioning of entrapped periosteum should be considered after failed closed reduction. In cases of supinated foot injuries of type II or triplane fractures requiring surgical fixation, a metaphyseal fracture plane parallel to the oblique coronal plane connecting the medial and lateral malleoli may facilitate appropriate metaphyseal fixation.

Surgical fixation of a triplane fracture should be undertaken if the residual fracture gap is 2 mm or greater after attempted closed reduction and casting.[32] A successful closed reduction can be predicted in displacements greater than 3 mm secondary to energy of the injury, soft-tissue interposition at the fracture site, and swelling.[22, 33]

An absolute contraindication is the presence of infective lesions and cellulitis. In the presence of significant swelling and blisters, adequate wound closure may not be achieved; therefore, surgery is delayed until the swelling resolves, and measures to reduce the swelling, such as limb elevation and cryocompressive therapy, are initiated immediately.

Nondisplaced triplane fractures (< 2 mm displacement) and extra-articular fractures can be managed with immobilization in a short leg cast for 4-6 weeks. Serial radiographs are obtained at weekly intervals during the first 3 weeks to check for late displacement. For displaced fractures, closed reduction is attempted with general anesthesia.

Closed reduction

General anesthesia and, at times, skeletal muscle relaxation are required to reduce the displacement. The mechanism of injury or the motion that produced the injury is reversed to obtain realignment. For medial fractures, the foot is positioned in external rotation; for lateral fractures, in internal rotation. Avoid more than two attempts at realignment: Each attempt causes additional trauma and bleeding and, possibly, further injury to the distal tibial growth plate. Closed reduction resulting in adequate fracture reduction in all planes is obtained in approximately 30-50% of triplane fractures.

Postreduction computed tomography (CT) scans and serial radiographs are needed to assess adequacy of reduction and guard against loss of reduction in the cast.

Adequate closed reduction is followed by 4-6 weeks of above-knee casting. The cast then is replaced with a below-knee cast to allow limited weight bearing with crutches for an additional 4 weeks. Following removal of the final cast, progressive return to normal activity is encouraged with ongoing physical therapy and range-of-motion (ROM) exercises.

Open reduction and internal fixation

Open reduction and internal fixation (ORIF) is performed for a triplane fracture demonstrating 2 mm or more of displacement after attempted closed reduction. The surgical approach depends on the fracture planes and can be anterolateral for lateral fractures or anteromedial for medial fractures. Small stab incisions are often needed for the placement of screws, either solid or cannulated.

The strength of operative screws and pins has increased progressively, while the diameters of operative screws have decreased. Titanium-based materials of greater diameter may be replaced by composite materials of lesser diameter, thus lessening the trauma associated with their operative placement.

Reduction and fixation of the metaphyseal spike may be all the surgery that is needed. An alternative is the placement of epiphyseal screws parallel to the joint surface, avoiding the growth plate and the ankle joint. More than one screw is needed, and the primary goal is reduction of the physeal fracture and joint surface.

Preoperatively, it is essential to detect all other injuries and address them adequately, as well as other comorbidities and preexisting medical conditions and needs. In persons with open fractures, tetanus immunization should be updated preoperatively if needed, and prophylactic antistaphylococcal antibiotics should be administered.

Intraoperatively, portable or fixed overhead radiography or C-arm fluoroscopy is needed to evaluate the results of internal fixation (ie, to confirm that the fracture is reduced and that screw placement is satisfactory) before the patient leaves the operating room. Wider availability of intraoperative CT C-arm or navigation technology will improve the accuracy of screw placement and internal fixation in these complex fractures.

Surgical fixation resulting in anatomic realignment of a triplane fracture can be viewed in the images below.

Lateral view at 60 days postoperatively of this 3-part triplane fracture in a 14-year-old male demonstrates accurate anatomic reduction. Two compression screws have been placed through a posterolateral incision. A vertical sclerotic line appears above, through, and below the screws, indicating healing of the realigned posterior metaphyseal spike. A 0.062 inch smooth Kirschner wire is observed.

Anteroposterior view at 60 days postoperatively of this 3-part triplane fracture demonstrates accurate anatomic reduction and 2 compression screws fixating the posterior metaphyseal spike. The horizontal 0.062 inch smooth Kirschner wire is accurately placed in the epiphysis from a medial approach through a single stab incision. Midway along the Kirschner wire a vertical line in the sagittal plane is observed, representing the original fracture through the epiphysis. Note that all fixation devices avoid the tibial growth plate.

The anterolateral epiphyseal fragment of a three-part injury is reduced and held with either a screw or a Kirschner wire (K-wire).[34] Before the patient leaves the operating room, a final set of postreduction radiographs is completed.

Arthroscopic reduction and internal fixation of two-part triplane fractures has been described as having advantages over traditional ORIF.[35, 36, 37, 38]

Postoperatively, standard incision care and suture removal are performed as directed by the physician. An above-knee cast is used for 4-6 weeks, followed by a below-knee partial weightbearing cast. When internal fixation has been accomplished and early physical therapy or ROM exercises are desired, the short leg cast may be replaced by a removable air splint.

In general, young healthy adolescents do well after a triplane fracture,[39]  even though it is a serious injury. Potential complications include the following:

• Tibial length growth retardation or deformity around the ankle secondary to epiphyseal growth plate injury
• Posttraumatic arthritis
• Postoperative infection
• Osteomyelitis
• Pressure injuries from the cast
• Fracture blisters
• Compartment syndrome

All patients with triplane ankle fractures must be monitored closely for potential complications. At discharge, the treating physician must make each patient aware of all of the follow-up requirements. Emphasis should be placed on the importance of patient involvement because such involvement has a direct bearing on the likelihood of a favorable outcome.

Typically, the initial above-knee cast is replaced 4-6 weeks after the injury, regardless of the treatment mode. This cast is replaced with a below-knee cast or a removable boot.