Plating of Distal Femur Fractures by Far Cortical Locking Using MotionLoc Screws

This prospective observational study documents healing of distal femur fractures that are
stabilized with locking plates using MotionLoc screws, which provide Far Cortical Locking
(FCL) to enable elastic fixation with locking plates. Locking plate constructs can be overly
stiff and may suppress fracture site motion required to stimulate fracture healing by callus
formation. Locking plates applied with novel MotionLoc screws allow for a controlled amount
of axial motion at the fracture site to actively stimulate callus formation and fracture
healing. Distal femur fractures (AO/OTA 33A and 33C) in 33 consecutive patients will be
stabilized in a percutaneous bridge plating approach using a titanium periarticular locking
plate with four FCL screws (Zimmer MotionLoc™) in the diaphysis. Standard locking screws
will be used for metaphyseal fixation. No bone grafts or bone morphogenic proteins will be
administered to enhance fracture healing. Healing will be assessed by the number of bridged
cortices on radiographs at week 6 (n=26), week 12 (n=22), and week 24 (n=13) and by CT at 12
weeks post surgery. Periosteal callus size will be objectively measured at the medial,
anterior and posterior cortices, and will be compared to a published series of historic
control data from 56 distal femur fractures treated with standard locked plating constructs.
Finally, radiographs will be inspected to determine the durability of implants and implant
fixation.

Inclusion Criteria:

1. Patients with distal femur fracture (AO/OTA Type 33A and 33C)

2. Patients 17 years of age and over.

3. Patients able to be operated on by selected surgeons at the participating centers.

Exclusion Criteria:

1. Pregnancy

2. Patients who are enrolled in an investigational treatment trial.

3. Patients who are not expected to survive the follow-up period.

4. Considered an inappropriate participant by the study physician.

5. Revision surgery

6. Patients currently incarcerated or awaiting incarceration.

7. Severe spinal injury with neurological deficit resulting in paralysis.

8. Fracture fixed more then 28 days after injury.

9. Acute or chronic local or systemic infections