DIFFIR – Geriatric Distal Femur Fixation Versus Replacement


The current standard of care for most intra-articular distal femur fractures (above the knee joint) in geriatric patients is a surgical fixation using plates and screws to hold the fracture pieces in the correct position, until the fracture as healed.

However, surgical fixation of these complex fractures in geriatric patients, is associated with significant complications, such as non-union (when the broken bone does not heal properly), infection and the need for revision surgery. Additionally, surgical fixation requires prolonged immobilization of of the affected limb (typically around 6-12 weeks post-operatively), which can lead to disability and other complications. Geriatric patients, especially those frail and with cognition impairment, are unable to adhere to the immobilization restrictions, which leads to an increased risk of fixation failure (broken bone does not heal).

Another treatment option for those patients is an acute distal femoral replacement (artificial knee), where damaged parts of the knee joint are replaced with artificial prosthesis. This procedure allows patients to walk immediately after the surgery and faster return to previous level of function, therefore avoiding the complications for immobilization.

There is a lack of guideline and evidence to suggest which surgical technique is best to provide superior function outcomes, lower complications and reduced costs. The proposed study seeks to answer this question by performing a large clinical trial comparing knee replacement versus surgical fixation in geriatric patients with distal femur fracture.

Full Title of Study: “DIFFIR: Geriatric Distal Femur Fixation Versus Replacement – A Randomized Controlled Trial of Acute Open Reduction Internal Fixation (ORIF) Versus Distal Femoral Replacement (DFR)”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: None (Open Label)
  • Study Primary Completion Date: June 10, 2022

Detailed Description

The proposed study is a prospective, randomized controlled trial, involving multiple centers across North America, to compare distal femur replacement (knee prosthesis) versus surgical fixation as a treatment for geriatric distal femur fracture.

Patients 65 years of age and older, with closed, displaced ( when the two ends of the bone are not lined up straight), comminuted (bone is in many pieces) distal femur fracture, who meet the inclusion criteria and agree to participate in the study, will be randomly assigned (by chance like flipping a coin) to receive either acute distal femoral replacement or surgical fixation.

The hypothesis is that patients in the acute distal femoral replacement group will have superior function, range of motion (full movement potential of a joint), general health status, reduced pain, and lower complications when compared to patients in the surgical fixation group.


  • Procedure: Distal femoral replacement
    • The distal portion of the femur (up to two thirds) is excised and replaced by a endoprosthesis incorporating a hinged total knee replacement.
  • Procedure: Surgical Fixation (ORIF)
    • A trained orthopaedic surgeon uses open or minimally invasive reduction techniques and achieves stable fixation with internal fixation devices (plates/screws or intramedullary nail) to restore structural integrity and alignment of the distal femur

Arms, Groups and Cohorts

  • Experimental: Distal femoral replacement (DFR)
    • Distal femoral replacement will be performed by excising the distal portion of the femur (up to two thirds) and replacing with a prosthesis incorporating a hinged total knee replacement. Surgical approach and implant selection will be at the discretion of the treating surgeon and within the standard of care. Surgeons performing this procedure will be qualified by training and experience in arthroplasty.
  • Active Comparator: Surgical Fixation (ORIF)
    • Surgical fixation of the distal femoral fracture will be performed with the goals of obtaining and maintaining anatomic reduction and stable fixation of the distal portion of the femur. Surgical approach and implant selection for the surgical fixation (ORIF) will be at the discretion of the treating surgeon and within the standard of care. Surgeons performing this procedure will be qualified by training and experience in trauma of the knee.

Clinical Trial Outcome Measures

Primary Measures

  • Oxford Knee Score (OKS)
    • Time Frame: Our primary outcome is knee pain and function as measured by repeated measures of the Oxford Knee Score at 3, 6, 9 and 12 -months post-surgery to detect a 5 point improvement on the OKS with 0.5 correlation between assessments.
    • A short questionnaire consists of 12 questions ranging from 0 to 48 points, designed to assess function and pain after knee replacement surgery. Higher values represent a better outcome. Scores between 40-48 indicate satisfactory joint function.

Secondary Measures

  • Daily morphine equivalent usage while in hospital
    • Time Frame: The outcome will be assessed daily from the day of the surgery until the patient gets discharge from the hospital (24 hours up to 7 days)
    • Assess patient’s cumulative intake of any drugs in the opioid class (in Milligram Morphine Equivalent) over 24 hours while in hospital.
  • Visual Analog Pain Scale (VAS)
    • Time Frame: Pain scale will be assessed immediately after surgery at 24 hours 48 hours, and then at each follow up visit at 3, 6, 9, 12, and 24 months post-surgery
    • Assess pain from a visual scale that ranges from 0 to 10. Straight line with the endpoints defining extreme limits such as ‘no pain at all’ (zero) and ‘pain as bad as it could be’ (ten)
  • Health status and quality of life – EQ-5D questionnaire
    • Time Frame: Questionnaire will be completed by patients at 3, 6, 9, 12, and 24 months post-surgery
    • The European Quality of Life 5 Dimensions (EQ5D) is a patient reported outcome where patients self rate their level of severity of health status and health related quality of life. Consists of 5 dimensions (mobility, selfcare, usual activities, pain/discomfort, anxiety/depression) and each one of them has 5 levels (no problems, slight problems, moderate problems, severe problems, and extreme problems) where patients will indicate how they feel regarding their health status and quality of life.
  • knee range of movement (ROM)
    • Time Frame: Test will be completed at each follow up visit at 3, 6,12 and 24 months post surgery
    • The therapist/assessor uses a goniometer (instrument that measures an angle of a joint) to measure the degree of knee flexion and extension of a patient. Knee Flexion – the measurable degree in which the leg (and knee joint) is bent. Knee Extension – The measurable degree in which the knee is extended (making the joint angle larger, or straightening the knee)
  • Timed Up and Go (TUG) test
    • Time Frame: Test will be completed at each follow up visit at 3, 6, 12 and 24 months post surgery
    • TUG is a simple test used to assess a person’s mobility (in seconds) and requires both static and dynamic balance. A line is placed on the floor 3 meters away from a chair where patient will be sitting. When instructed to “GO” patient will stand, walk to a line on the floor at his/her regular pace, turn around and walk back to the chair and sit down. The longer it takes for subject to complete the test, higher is the risk of fall and lower is the its functional mobility. Reference values are: 60-69 years old = 8.1 seconds; 70-79 years old = 9.2 seconds; 80-99 years old = 11.3 seconds. Over 14 seconds is associate with high risk of fall
  • Knee Extension lag
    • Time Frame: Test will be completed at each follow up visit at 3, 6,12 and 24 months post surgery
    • It is a function of tight muscles weakness that assess the patient inability to achieve the final 15 degrees of active knee extension. The therapist/assessor will evaluate if the patient can extend the knee fully with help (passive movement), but have limited range of movement when perform an active knee extension. The therapist/assessor will record the degree of limitation for each patient. uses a goniometer (instrument that measures an angle of a joint) to measure the degree of knee flexion and extension of a patient. Knee Flexion – the measurable degree in which the leg (and knee joint) is bent. Knee Extension – The measurable degree in which the knee is extended (making the joint angle larger, or straightening the knee)

Participating in This Clinical Trial

Inclusion Criteria

  • Male and female patients
  • 65 years and older
  • Isolated fracture of the distal femur (Classification 33)
  • Fracture is amendable to both treatments
  • Fracture is acute (within 2 weeks from time of injury)
  • Patient was ambulatory (with or without walking aids) prior to the injury
  • Independent or moderately frail with score of 3 to 6 on the Clinical Frailty Scale
  • Patient is able to read and understand English, French, or Spanish
  • Patient or substitute decision maker is able to provide written informed consent to participate in the study

Exclusion Criteria

  • Active or previous infection around the fracture (soft tissue or bone)
  • Open fracture
  • Bilateral femur fractures
  • Major vascular injuries requiring intervention, compartment syndrome and major neurologic 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 the 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 contra-indication to surgery

Gender Eligibility: All

Minimum Age: 65 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • St. Michael’s Hospital, Toronto
  • Collaborator
    • Mount Sinai Hospital, Canada
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • Amir Khoshbin, MD, Principal Investigator, St Michael’s Hospital – Unity Health Toronto
    • Jesse Wolfstadt, MD, Principal Investigator, Mount Sinai Hospital, University of Toronto


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