[Osteochondral fractures of the external femoral condyle after traumatic patellar dislocation during physical exercise in children].

PURPOSE OF THE STUDY

Nineteen osteochondral fractures of the lateral femoral condyle associated with acute traumatic patellar dislocation resulting from sport injury in children were studied. The purpose of this study was to specify clinical and radiological features.

MATERIAL AND METHOD

This study was led with special care to injury circumstances, fracture visibility on X-rays, size and location of the fracture, treatment delay, presence of femoro-patellar dysplasia signs. Treatment results were evaluated on knee pain, bone consolidation and recurrent dislocation.

RESULT

Thirteen boys and six girls aged 8 to 16 years (average 14 years) were included. The injury resulted from a rotatory-compression stress in 75 per cent cases. The patella was always in place at the time of examination. Thirteen fractures were diagnosed within 24 hours and 5 fractures were diagnosed within 1 week after injury. One fracture was not visible on X-rays and was diagnosed 6 weeks after injury. Only the lateral view showed the fracture in more than one case out of two. Seven patients whose fracture was less than 5 mm, or involving a non-weight-bearing portion, or diagnosed within more than ten days after injury, were treated by knee arthroscopy and removal of the osteochondral fragment. Twelve patients were treated by arthrotomy and excision (one case) or replacement of the osteochondral fragment (11 cases). The replaced fracture was fixed with biological glue ten times, and screwed once. The knee was immobilised in a cylinder cast and weight-bearing prohibited for six weeks. Bone consolidation was obtained in 9 cases out of 11, in an average of 8 weeks. Knee pain occurred 5 times. Recurrence of the dislocation occurred 3 times within 6 months. Eighty per cent of these children showed patello-femoral dysplasia.

DISCUSSION

This fracture complicated 31.6 per cent of traumatic patellar dislocation resulting from sport injury in children which we observed during the last ten years. It may be overlooked if it is suspected and carefully looked for by radiographic examination including antero-posterior, lateral, oblique and true skyline views of the patella. The presence of fat in the hemarthrosis may help. Early surgery is recommended. Arthroscopy may be performed to evaluate fracture location and size. After ten days, host area begins to fill in and free fragment will not fit back well. Fragments less than 5 mm, or involving a non-weight-bearing portion, or diagnosed within more than ten days after injury, may be removed.

CONCLUSION

Lateral femoral condyle osteochondral fractures are associated with nearly one third of traumatic patellar dislocation resulting from sport injury in children. A detailed radiographic examination can help diagnosis. Treatment depends on the delay after injury, the size and location of the fracture.