[Fractures of the tibial tuberosity associated with avulsion of the patellar ligament in adolescents].

PURPOSE OF THE STUDY: Avulsion fracture of the tibial tuberosity is considered as a relatively uncommon adolescent injury. The avulsion of the patellar ligament may occur as part of the injury. Two cases of sixteen year old boys with this kind of injury have been reported. Fractures are described using Ogden et al. classification : type I is an avulsion fracture of the most distal portion of the ossification center of the tubercle ; type II, an upward angulation of the lip fragment ; type III, a fracture of the lip fragment with propagation of the fracture-line into the knee joint. Each type is subdivised into A (no comminution) and B (comminution). Frankl et al. in 1990 address the possibility that patellar ligament avulsion may occur as part of the injury (type C).

CASE REPORTS: Two sixteen-year old boys suffered from sharp pain in the knee during a jump while playing basketball. Radiographic evaluation demonstrated an avulsion fracture of the tibial tubercle type III C. The osseous fragment was sutured with trans-osseous suture. The fixation was protected with a tension band passed above the patella and distally in the tibia. It was removed at six weeks. One patient was not reviewed and the other had no complaint one year after.

DISCUSSION: Avulsion fracture of the tibial tuberosity Ogden type I and II is generally treated by plaster cast. When the patient is unable to extend his knee actively, an avulsion of the patellar ligament should be suspected. In this case, Frankl et al. proposed radiographic evaluation: the distance between the distal end of the patella and the avulsed fragment was noted to increase during flexion. Avulsion of the distal tuberosity usually occurs just prior to complete closure of the proximal tibial physis. Interfragmental transphyseal screws can thus be used safely. In the younger patient or in extensive comminution, tension band wire should be used. The use of a tension band between patella and tibia to protect the ligament reinsertion provise early knee mobilisation (between 0 and 60 degrees). It should be removed within six weeks.

CONCLUSION: Avulsion fracture of the tibial tuberosity is rare. When conservative treatment is indicated, it is important to search an avulsion of the patellar ligament. When such an injury is suspected, lateral radiographs of the knee should be made in flexion as well as in extension. We believe that treatment should include open reduction and internal fixation associated with a protect tension band allowing early rehabilitation.