Fixation of distal femoral fractures with the Less Invasive Stabilization System: a minimally invasive treatment with locked fixed-angle screws.

BACKGROUND

The Less Invasive Stabilization System (LISS) is an internal fixator, which combines closed reduction of the diaphysis or metaphysis of distal femur fractures with locked unicortical screw fixation.

METHODS

In a retrospective consecutive study, 50 patients with Association for the Study of the Problems of Internal Fixation/Orthopaedic Trauma Association (AO/OTA) type 33-A1 to 33-C3 fractures were treated with the LISS between January 1999 and December 2003. Final results were assessed using the functional score of Neer after a median follow-up of 29 months (15-48 months).

RESULTS

Fifteen male and 16 female patients were followed up. The mean age was 49 years (17-90 years). Deep wound infection was seen in one patient (3%) and malpositioning with cutting-out of the proximal screws was in two patients (6%). All other fractures healed uneventfully without bone graft requirements after a mean of 12 weeks (7-20 weeks). A revised osteosynthesis was performed for correction of a valgus deformity of 20 degrees after 4 months. There was no difference in leg length exceeding 2 cm. One patient had a valgus deformity of 10 degrees combined with a rotational deformity of 10 degrees. Range of motion of the knee joint was >120 degrees in 15 patients (48%); 12 (39%) had a range of motion between 90 degrees and 120 degrees and 4 (13%) between 70 degrees and 90 degrees. The function according to the Neer score was excellent in 15 (48%), good in 10 patients (32%), and fair in 6 patients (20%). The mean Neer score was 80 (60-100).

CONCLUSIONS

The LISS promotes early mobilization and rapid rates of bony and clinical healing without bone grafting with low rates of infection.