Introduction: Between 1986 and 2001 174 cases of Proximal Femoral Focal Deficiency (PFFD) have been treated in our institution. The treatment of PFFD is difficult, many possible traps must be avoided.

Patients: According to the Aitken classification we had 104 cases type A, 41 type B, 16 type C, and 13 type D. The age of the patients treated in our institution had a range between 1 week and 18 years. 12 pelvic and 16 intertrochanteric osteotomies, 34 femoral and 20 lower leg lengthenings have been done up to date.

Complications: Depending on our learning curve the difficulties were bigger in the first years of lengthening PFFD patients. 3 femora fractured after removal of the external fixator, 1 hip dislocated one year after end of lengthening. Meanwhile only few complications occur any longer.

Disscussion: In general, lengthening is possible in type A and B and can be delayed until preschool age. We strongly recommend hip MRI imaging prior to any operation. In severe leg length discrepancy several lengthening procedures must be planned. We recommend lengthening if the final leg length discrepancy at end of growth will not be more than 22 cm. Patients should be aware that lengthening in PFFD needs perfect cooperation, is long lasting and bears certain risks.