NCT04076735.

Study name	DIFFIR: geriatric distal femur fixation versus replacement – a randomized controlled trial of acute open reduction internal fixation (ORIF) versus distal femoral replacement (DFR)
Methods	Prospective, randomised controlled trial, involving multiple centres across North America
Participants	Estimated 140 participants Inclusion criteria: men and women age ≥ 65 years; isolated fracture of distal femur (Classification 33); fracture is amenable to both treatments; fracture is acute (within 2 weeks from time of injury); ambulatory (with or without walking aids) prior to injury; independent or moderately frail with score of 3–6 on Clinical Frailty Scale; able to read and understand English, French or Spanish; participant or substitute decision maker is able to provide written informed consent to participate in study. Exclusion criteria: active or previous infection around fracture (soft tissue or bone); open fracture; bilateral femur fractures; major vascular injuries requiring intervention, compartment syndrome and major neurological injuries; pathological fracture excluding osteoporosis; previous surgical fixation or total knee replacement of the distal femur or proximal tibia; previous surgical fixation or hemi/total replacement of hip; current or previous extensor mechanism (patellar tendon, quadriceps tendon or patella fracture) disruption or repair; polytrauma (Injury Severity Score > 15) or any associated major injuries of the lower extremities; previous medical diagnosis of dementia; medical or surgical contraindication to surgery.
Interventions	Participants were allocated to either: distal femoral replacement; open reduction internal fixation.
Outcomes	Primary outcome OKS at 3, 6, 9 and 12 months postsurgery to detect a 5‐point improvement on the OKS with 0.5 correlation between assessments Secondary outcomes Daily morphine equivalent usage while in hospital (will be assessed daily from the day of the surgery until the patient gets discharge from the hospital (24 hours up to 7 days)) VAS assessed immediately after surgery at 24 hours, 48 hours, and at each follow‐up visit at 3, 6, 9, 12 and 24 months postsurgery Health status and quality of life – EQ‐5D questionnaire at 3, 6, 9, 12 and 24 months postsurgery Knee range of movement at 3, 6, 12 and 24 months postsurgery Timed Up and Go test at 3, 6, 12 and 24 months postsurgery Knee extension lag at 3, 6, 12 and 24 months postsurgery
Starting date	16 March 2020
Contact information	Amir Khoshbin, MD & Jesse Wolfstadt, MD St Michael's Hospital ‐ Unity Health Toronto, ON, Canada
Notes

AO: Arbeitsgemeinschaft für Osteosynthesefragen; CRP: C‐reactive protein; CT: computed tomography;  EQ‐5D: EuroQol 5 Dimensions; ESR: erythrocyte sedimentation rate; OKS: Oxford Knee Score; OTA: Orthopaedic Trauma Association; RUST: radiographic union score for tibial; VAS: Visual Analogue Scale.