[Corrective osteotomies of the distal femur with retrograde intramedullary nail].

Deformities of the distal femur are usually corrected by supracondylar osteotomy. In the "classical" procedure the bone cut is performed with an oscillating saw, and internally fixed using a plate. This technique is hampered first by an invasive approach and second by limited corrective options in case of complex deformities. A supracondylar bone cut by focal dome osteotomy or drill osteoclasis in combination with internal fixation by retrograde intramedullary nailing (RN) might be a promising alternative procedure. 12 patients with multidimensional post-traumatic deformities of the distal femur were prospectively enrolled in a study to investigate this new minimal-invasive technique. In all patients a meticulous analysis of leg geometry was done pre- and postoperatively. Details of operative planning, osteotomy and fixation procedure are given as well as the postoperative treatment. 7 corrective osteotomies were one-step procedures, in 5 patients additional lengthening over the RN was performed using unilateral external fixation. The mean follow-up was 15 (range 7-27) months. All of the osteotomies healed in a normal expected time frame. All patients had important functional benefits. In 11 patients the goal of deformity correction was achieved. In one patient the correction in the frontal plane remained insufficient. 6 months after the completion of femoral lengthening osteomyelitis developed in one patient, probably due to a pin-track infection. The infection subsided after early removal of the RN. No further complications were observed. The presented technique is demanding concerning pre-operative planning and surgical realization but it offers a minimal-invasive and promising approach for the correction of multidimensional femoral deformities.