Far Cortical Locking Versus Standard Constructs for Distal Femur Fractures (FCL)

A Multicentre, Randomized Trial of Far Cortical Locking Versus Standard Constructs for Acute, Displaced Fractures of the Distal Femur Treated With Locked Plate Fixation

To determine if Far Cortical Locking screws increase fracture healing rates at 3 months in Closed Distal Femur Fractures in adults when compared to Standard screw constructs. Fracture healing at 3 months will be assessed via radiographic and clinical assessment of the fracture. Null Hypothesis: There will be no difference in fracture healing at 3 months post-fixation between subjects treated with far cortical locking screw or standard screw fixation.

A multicentre randomized controlled trial with a sample size of 138 subjects. Primary Outcome is fracture healing at 3 months via radiographic and and clinical assessment. Radiographic healing will be defined as bridging of one or more cortices as seen on x-ray. Radiographic assessment will be centrally adjudicated by a committee of three study investigators. Clinical healing will be assessed using the Function Index for Trauma (FIX-IT). Secondary outcome measurements will include patient-reported quality of life and CT quantification of fracture callus volume. Quality of life will be measured with the Short-Form 36 Version 2 (SF-36) instrument at all follow-up intervals. A CT scan of the fracture site will be performed at the 3 month follow-up. Using a quantitative protocol the volume of callus will be measured and the extent of cortical bridging will be assessed. Additional secondary outcomes include radiographic and clinical healing, as well as patient-important complications. These will include adverse events, delayed union (>6 months), non union (failure for fracture healing to progress on serial x-rays between 6 and 9 months), malalignment (>5 degrees), hardware failure, infection, and reoperation. Information surrounding the type of complication, duration, management and/or treatment of all complications will be recorded A Data Safety Monitoring Board will be established to independently monitor trial data. Specific inclusion criteria: Men or women ages 18 years or older Displaced distal femur fracture (OTA 33A or 33C) as seen in radiographs Planned treatment using a distal femur locking plate Ability to read and speak English or availability of translator willing to assist with completion of study forms Fractures < 14 days post injury Provision of informed consent Specific exclusion criteria: Open distal femur fracture requiring flap or vascular repair (grade 3b or 3c) Planned fixation strategy includes interfragmentary lag fixation of non-articular fractures Active local infection Limited life expectancy due to significant medical co-morbidity or medical contraindication to surgery Inability to comply with rehabilitation or form completion Likely problems, in the judgment of the investigators, with maintaining follow-up (i.e. patients with no fixed address, patients not mentally competent to give consent, etc.) Non-ambulatory patients Lack of bone substance or poor bone quality which, in the surgeon's judgment, makes locked plate fixation impossible Periprosthetic fractures Any concomitant lower-extremity injury that requires non-weight-bearing beyond 6 weeks post-operative Addition of bone graft, bone graft substitute or BMP Pregnant women

Radiographic fracture healing defined as bridging of 1 or more cortices. Clinical fracture healing assessed with FIX-IT. Using the win ratio method, we hierarchically assessed radiographic healing, followed by clinical fracture healing. The pairwise comparison proceeds in a hierarchical fashion, using radiographic healing, followed by the FIX-IT score when patients cannot be differentiated based on radiographic healing. For each pairwise comparison, the treatment groups are assigned a win, loss, or tie. We calculate the win ratio as the number of wins in the FCL screw treatment group divided by the number of wins in the Standard screw group.

Union is defined as the bridging of 1 or more cortices with stable fixation by three months post-fixation.

We assessed clinical fracture healing using the Function Index for Trauma (FIX-IT) score. The FIX-IT instrument quantifies clinical healing by aggregating a 0- to 6-point assessment of weight-bearing and fracture site pain for a maximum score of 12 points, indicating the highest level of functional healing.

Specific inclusion criteria: Men or women ages 18 years or older Displaced distal femur fracture (OTA 33A or 33C) as seen in radiographs Planned treatment using a distal femur locking plate Ability to read and speak English or availability of translator willing to assist with completion of study forms Fractures < 14 days post injury Provision of informed consent Specific exclusion criteria: Open distal femur fracture requiring flap or vascular repair (grade 3b or 3c) Planned fixation strategy includes interfragmentary lag fixation of non-articular fractures Active local infection Limited life expectancy due to significant medical co-morbidity or medical contraindication to surgery Inability to comply with rehabilitation or form completion Likely problems, in the judgment of the investigators, with maintaining follow-up (i.e. patients with no fixed address, patients not mentally competent to give consent, etc.) Non-ambulatory patients Lack of bone substance or poor bone quality which, in the surgeon's judgment, makes locked plate fixation impossible Periprosthetic fractures Any concomitant lower-extremity injury that requires non-weight-bearing beyond 6 weeks post-operative Addition of bone graft, bone graft substitute or BMP Pregnant women

Claireaux HA, Searle HK, Parsons NR, Griffin XL. Interventions for treating fractures of the distal femur in adults. Cochrane Database Syst Rev. 2022 Oct 5;10(10):CD010606. doi: 10.1002/14651858.CD010606.pub3.