Pediatric fractures most frequently involve physeal plates. Theses physes are cartilaginous and represent the weakest parts of a bone. In a Tillaux fracture, the asymmetrical closure of the physeal plate contributes to the mechanism of injury in such a way as to create the classic Tillaux fracture pattern in adolescent patients. This fracture is classified as a Salter-Harris type III fracture and is, therefore, an intraarticular fracture. The physis involved is the distal tibial physis, and the intraarticular portion of the fracture pattern involves the distal tibial bony epiphysis. The fracture is named for Paul Jules Tillaux who was a French physician who practiced medicine and surgery in Paris. In 1892 he was the first physician to describe the Salter-Harris type III fracture of the distal tibia.
The cause of a Tillaux fracture is a traumatic injury to the ankle. It is felt that an external rotatory force is needed to create this fracture pattern. This motion and the resulting force causes a pull of the anterior inferior talofibular ligament on its distal tibial attachment and results in an avulsion of the lateral part of the distal bony epiphysis. The injury may be misdiagnosed as a sprain unless a radiographic investigation of the ankle is done.
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. The fracture does not have a predilection for boys or girls. However, there is some increased occurrence in adolescents who participate in sports activities because of the increased stresses 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.
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 which 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.
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.
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. The 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.
Radiographic assessment of a Tillaux fracture will reveal the classical pattern of an anterior lateral physeal separation and extension of the fracture through the bony epiphysis into the ankle joint. If the examiner is unsure of the x-ray findings, and additional evaluation by CT scan may more clearly show a fracture pattern. Differential diagnosis should include that of a triplane fracture which occurs in slightly younger children before partial closure of the physis and extends through an additional plane in the distal tibial metaphysis. It is an atypical fracture pattern and involves both a Salter-Harris type II and a Salter-Harris type III injury. It is not a true Salter-Harris type IV, although some people may refer to it as such. Thin cut CT examination of the ankle are sometimes necessary to correctly evaluate the injury.
The amount of displacement drives proper treatment of a Tillaux fracture. Ideally, with little displacement, the fracture can be managed non-operatively with the application of a short leg cast with the ankle slightly inverted to help hold the fracture in place. Fractures that are displaced and disrupt the articular surface of the distal tibia need to be considered for possible operative management. If the joint surface is disrupted more than 1 mm, some surgeons feel the joint should be reduced and stabilized in either a cast (if the reduction will hold) or stabilized by internal fixation. Some surgeons may use 2 mm as their threshold for reductions. If open reduction and internal fixation are used, the physis is not protected as it would be in younger children because of the potential for additional growth is minimal. Some surgeons will place screw fixation through the physis. Another surgeon may still wish to protect the physis and place a screw parallel to the articular surface of the ankle in the space between the physis and the joint. This avoids any fixation through the physis. The approach for screw placement is anterior lateral, and this allows for visualization of the fragments and ankles joint without violation of other structures. Fracture repair is usually augmented with cast or splints.
Differential diagnosis as mentioned include, ankle sprain of the anterior talofibular ligament and triplane injury.
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.
Do not assume an ankle has a simple sprain and forget to get x-ray evaluation of pediatric ankle injuries. The physis is not as strong as ligamentous structures, and physeal fractures occur before ligamentous injuries occur.