Tillaux Fracture

Etiology

The cause of a Tillaux fracture is a traumatic injury to the ankle. It is felt that a supination external rotation injury is needed to create this fracture pattern. Also, medial rotation of the leg on a fixed foot has been reported as a mechanism of injury [7]. This motion and the resulting force cause a pull of the anterior inferior tibiofibular ligament on its distal tibial attachment and results in an avulsion of the anterolateral part of the distal tibial epiphysis (The Chaput tubercle). The injury may be misdiagnosed as a sprain unless a radiographic investigation of the ankle is done.[8][9]

The distal tibial physeal closure occurs in a predictable pattern in the 18 months transitional period before skeletal maturity. The central portion of the physis closes first followed by the anteromedial then posteromedial portions and the lateral portion closes last. This specific closure pattern contributes to the etiology of the juvenile transitional ankle fractures ie. Tillaux and Triplane fractures.

Epidemiology

For the Tillaux fracture pattern to occur, portions of the distal tibial physis should have closed. This occurs in adolescent children who are within the last year of physeal closure. Before this time, the physis is completely open, and this pattern of fracture will not occur. Tillaux fracture is more common in females. However, there is some increased occurrence in adolescents who participate in sports activities because of the increased stress these activities place on the ankle. Because of the earlier closure of physeal plates in females as compared to males, the injury pattern most frequently occurs at an earlier age in girls than in boys.[10]

Pathophysiology

Closure of the physeal plates in both males and females in under the control of estrogen. Estrogen slows the proliferation, and hypertrophic changes in chondrocytes which then become replaces by bony elements. This is why Tilleau fractures usually occur at a younger age in females who will produce estrogen at an earlier age as compared to males. As the physeal plate closes, it closes in a distinct pattern. The central portion of the physis closes first followed by the anterior and medial portions. The anterior-lateral portion of the plate closes last. When an external rotatory force is applied to the physis, the weakest portion of the physis will fail first. This is the anterior lateral portion that will avulse or in other words fracture. As the force travels through the physis, it will reach a point where the physis is closed and then be directed through the weakest and most easily fractured part of the bone, the distal, bony epiphysis. This creates the classic Salter-Harris III fracture pattern of a Tillaux fracture.

Histopathology

The cartilaginous physeal plate of a long bone is divided into specific areas or zones. Each area has its distinct characteristics. There are 5 zones in an epiphyseal cartilaginous plate. These are the resting zome, the proliferative zone, the hypertrophic zone, the zone of provisional calcification, and the ossification zone. The resting zone is composed of a germinal layer of cells that differentiate into chondrocytes. In the proliferating zone, the chondrocytes divide by mitosis and begin to organize into columns of cells within a matrix of proteoglycans. In the hypertrophic zone, the chondrocytes grow larger and begin to differentiate terminally. This is the weakest zone of the physis, and it is the zone through which fractures occur. In the zone of provisional calcification, the matrix becomes calcified and is ready for osteogenesis (bone formation) chondrocytes die. In the zone of ossification, the calcified matrix is replaced by a bony matrix and osteocytes.

History and Physical

Adolescent patients present after injuring their ankle. They may remember the exact mechanism of injury, but frequently just remember twisting the ankle and feeling it (give out).

Physical examination most commonly will demonstrate pain and swelling in the anterior lateral part of the ankle. This presentation is very similar to an ankle sprain or injuries to the anterior talofibular ligament. Because of this presentation, the injury is frequently mistaken for an ankle sprain. However, the fact that the physis may be still open in an adolescent and that the physis is weaker than the ligamentous anterior talofibular ligament should direct the examiner to order additional objective x-ray evaluations of the ankle to rule out any possible bony injury. A closer evaluation could suggest a joint effusion. This represents bleeding into the joint from the intraarticular extension of the fracture and should further alert the examiner to the need for further objective evaluation of the injury.

Evaluation

Radiographs: Anteroposterior, lateral, and Mortise views. Radiographic assessment of a Tillaux fracture will reveal the classical pattern of anterior lateral physeal separation and extension of the fracture through the bony epiphysis into the ankle joint. It is a Salter-Harris type III fracture of the anterolateral distal tibial epiphysis. 

CT scan: This is the preferred imaging modality in evaluating Tillaux fracture and its degree of displacement. CT is more sensitive than plain radiographs in evaluating fractures with as little displacement as 2 mm.[11] 

Treatment / Management

The amount of displacement drives the proper treatment of a Tillaux fracture. Regardless of which treatment option is adopted, an anatomic reduction is the main target. Ideally, with little displacement as < 2 mm, the fracture can be managed non-operatively with closed reduction and immobilization in a cast. Closed reduction is usually achieved by foot internal rotation. Alternatively, the reduction can be attempted by dorsiflexion and pronation of the foot followed by an internal rotation. This is usually accompanied by the application of a short leg cast with the ankle slightly inverted to help maintain the fracture reduction. Casting is usually for 4 weeks non-weight bearing followed by additional 2 weeks in a walker boot to allow ankle range of motion. 

Fractures that are displaced > 2 mm with disruption of articular congruity of the distal tibia need to be considered for operative management as per the following:

Closed Reduction and Percutaneous Pinning (CRPP): Reduction can be achieved as mentioned above or by using a K-wire in the fracture fragment as a joystick. The quality of reduction can be evaluated intraoperatively either by fluoroscopy or arthrogram. If a reduction is satisfactory, the fracture is fixed with K-wires or cannulated screws across the epiphysis parallel to the articular surface.[12][13][12](B2)

Open Reduction and Internal Fixation (ORIF): Anterolateral approach is used to allow direct visualization of the articular surface for optimal reduction. The fracture is reduced with internal rotation and the reduction is held with either transepiphyseal K wires or periarticular clamp. Fixation is with either K wires or cannulated screws across the epiphysis. Children who develop Tillaux fracture are usually approaching skeletal maturity, so crossing the physis will rarely affect remaining growth. Fracture fixation is usually augmented with cast or splints for 4 weeks followed by a walker boot for additional 2 weeks to allow ankle range of motion exercises.[14][15][16][17][18][19][18](B3)

Arthroscopically assisted reduction and fixation: The anterolateral portal is usually used. It allows direct anatomic reduction of the fracture with minimal intervention.[20][21][22]  (B3)

Differential Diagnosis

Differential diagnoses include ankle sprain of the anterior talofibular ligament (ATFL) and triplane fracture. A triplane fracture occurs in slightly younger children before partial closure of the physis and extends through an additional plane in the distal tibial metaphysics. It is a multiplanar injury consisted of three classically described fracture fragments [23]. It has been described as a complex Salter-Harris type IV with its components in three planes. On the AP radiographs, the epiphysis is fractured in the sagittal plane and appears as a Salter-Harris type III injury. The physis is fractured in the axial plane. The metaphysics is fractured posteriorly in the coronal plane and appears on the radiographs as a Salter-Harris type II injury. Thin cut CT examination of the ankle are sometimes necessary to correctly evaluate the injury. Triplane fracture is more common in boys, contrary to Tillaux fracture which is more common in girls.

Prognosis

The prognosis for full recovery is excellent, and the usual adolescent level of activity frequently is enough to negate the need for physical therapy after healing.

Complications

Posttraumatic ankle arthritis.

Ankle stiffness and Pain.

Premature growth arrest: rare incidence as Tillaux fractures happens near the end of physeal growth.[24]