Are Locking Constructs in Distal Femoral Fractures Always Best? A Prospective Multicenter Randomized Controlled Trial Comparing the Less Invasive Stabilization System With the Minimally Invasive Dynamic Condylar Screw System

Objectives:The purpose of this clinical study is to determine whether the rate of fracture healing and fracture union, repaired with a locked device, will be as good as or better than standard nonlocking bicortical fixation in distal femoral fractures.Design:Institutional review board-approved, multicenter prospective randomized controlled trial.Setting:Seven level 1 trauma centers across Canada.Patients:Fifty-two patients with distal femoral fractures (AO/OTA 33A1 to 33C2) were enrolled in the randomized trial. Twelve AO/OTA 33C3 fractures were excluded from the randomized trial but followed up as a nonrandomized cohort.Intervention:Patients were treated through a standardized minimally invasive approach. Fractures were randomized 1:1 to treatment with the locked Less Invasive Stabilization System (LISS; Synthes, Paoli, PA) or the dynamic condylar screw (DCS). The nonrandomized cohort was treated at the surgeon's discretion.Main Outcome Measurements:Primary outcomes were time to radiological union and number of delayed/nonunions at 12 months. Secondary outcomes were postoperative function and complications.Results:Fifty-two patients were randomized including 34 women and 18 men. The mean age was 59 years. Twenty-eight patients were treated with the LISS and 24 with the DCS. There was no statistically significant difference between the LISS and the DCS in terms of the number of fractures healed, time to union, or functional scores. Complications and revisions were more common in the LISS group. There were 7 reoperations in the LISS group and one in the DCS group. Only 52% of the LISS group healed without intervention by 12 months compared with 91% in the DCS group.Conclusions:There was no advantage to the locking plate design in the management of distal femoral fractures in this study. The higher cost of the locking plates, challenges in technique, and lack of superiority have led the authors to discontinue the use of this lateral unicortical locking device in favor of other devices that allow locked or nonlocked bicortical fixation, articular compression, and bridging of the comminuted fracture segments. The cost-effective treatment for a subgroup or periarticular fractures may be a fixed-angle nonlocked device in patients with reasonable bone quality.Level of Evidence:Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.