[Lengthening of proximal femoral focal deficiency using a hybrid fixation with inclusion of the knee joint].

BACKGROUND: A major problem in lengthening a short femur in proximal focal deficiency of the femur (PFFD) is the development of contractures and dislocation of the hip and knee joint. The knee joint is particularly prone to dislocation because of the cruciate ligament insufficiency associated with PFFD. Axis deviations also need specific attention. PATIENTS AND METHODS: In four patients (age 2.5-11 years) with PFFD (PAPPAS class III in one patient and VII in three patients), five femoral lengthenings with mechanical axis corrections were performed by the callotasis technique using a hybrid fixation system (Monotube/Triax) connecting the femur and the tibia with a fixed hinged knee joint to protect the knee against contracture and dislocation.
RESULTS: All patients retained their hip and knee function. Hip flexion contracture during lengthening may make inclusion of the hip joint into the fixation system necessary, but was not carried out in the four patients presented.
CONCLUSION: Four consecutive lengthenings of the femur with focal deficiency were carried out under protection by a hinged knee bridging external fixator. A dislocation could be prevented in all patients. We consider that such a system could be used during these lengthening procedures.