[Pathophysiology of posttraumatic deformities of the lower limbs during growth]

Posttraumatic deformities after pediatric fractures are either the result of incomplete or failed remodeling, complete or partial stimulation of the growth plates, or complete or partial closure of a growth plate. In contrast to fractures of the upper extremities, spontaneous remodeling should not be intentionally integrated in the treatment algorithm. Thus, stimulative growth disturbances with subsequent changes of the leg length can be prevented. Therefore, one should strive for anatomical alignment and rotation without shortening. The latter provokes remodeling, with activation of the adjacent physis. Growth disturbances with partial stimulation typically occur after metaphyseal bending fractures of the proximal tibia. If minimal valgization is overlooked, growth disturbances will lead to a progressive valgus deformity. Partial closure of a growth plate is still inevitable after epiphyseal fractures (Salter-Harris type III and IV) as well as after simple epiphysiolysis (Salter-Harris-type I, II). The resulting deformity depends on the size of the physeal closure, its localization, and on the remaining growth. A "waterproof" reduction and osteosynthesis of type III and IV fractures may well diminish the risk of a partial physeal closure but will not reliably prevent it. It will occur in about 35% after physeal fractures at the distal femur, in 30% at the proximal and 20% at the distal tibia. Based on this knowledge patients and parents should be informed correspondingly and follow-up should be continued until skeletal maturity.