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

MotionLoc Study: Healing of Distal Femur Fractures Stabilized With a Flexible Plating Construct Using MotionLoc Screws

The objective of this study is to document callus formation and healing of fractures stabilized with locking plates utilizing modern MotionLoc screws that provide controlled axial micro-motion to actively promote fracture healing.

Study Overview

• Status: Completed
• Conditions: Fracture of Distal Femur

Detailed Description

Rigid locked plating constructs can suppress fracture healing, particularly at the near cortex adjacent to the plate where interfragmentary motion is minimal. Dynamic fixation with Far Cortical Locking (FCL) screws reduces construct stiffness and induces axial interfragmentary motion to stimulate symmetric callus formation and healing. Two versions of FCL screws are commercially available, but the clinical durability of this novel concept has not been documented to date. This prospective observational study documented our early clinical experience with MotionLoc® FCL screws for stabilization of distal femur fractures to assess their durability and potential complications.

Thirty-two consecutive patients with 33 distal femur fractures (AO/OTA types 33-A and 33-C) were prospectively enrolled at three trauma centers. Fractures were stabilized by plate osteosynthesis with MotionLoc® FCL screws without supplemental bone graft or bone morphogenic proteins. Thirty patients with 31 fractures were available for follow-up until union or revision. Follow-up visits at 6, 12, and 24 weeks comprised functional and radiographic assessment of implant fixation and fracture healing, including computed tomography scans at week 12. The primary endpoint was fracture healing in absence of complications and revision.

There was no incidence of implant breakage or diaphyseal fixation failure. Thirty of 31 fractures healed within 15.6 ± 6.2 weeks, as evident by bridging callus and pain-free load bearing. There were two revisions, one at 5 days post surgery to correct a mal-rotation, and one at 6 months post surgery to revise a non-union. Periosteal callus distribution at week 6 was symmetrical, with similar amounts of callus at the medial cortex (35%) anterior cortex (30%) and posterior cortex (35%). In 23 fractures (74%), callus formation extended to the lateral cortex under the plate.

Absence of hardware and fixation failure suggests that dynamic plating of distal femur fractures with FCL screws provides safe and effective fixation. Moreover, the amount and symmetric distribution of periosteal callus suggests that dynamic fixation with FCL screws may promote increased fracture healing over standard locked plating. However, this hypothesis on the stimulatory effect of dynamic fixation on fracture healing requires investigation in a future randomized control trial.

• Study Type: Observational
• Enrollment (Anticipated): 33

Contacts and Locations

Study Locations

• United States
  • Oregon
    • Portland, Oregon, United States, 97232
      • Legacy Health System

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 17 years and older (Child, Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Probability Sample

Study Population

Distal femur fractures (AO/OTA Type 33A and 33C)

Description

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
10. Periprosthetic fractures

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Femur Fractures; Patients with Distal Femur Fractures

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fracture Healing	Fracture healing is defined clinically by the ability of pain-free weight bearing, and radiographically by callus formation and bridging.	6, 12, and 24 weeks post surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Periosteal Callus Size	Periosteal callus size is assessed at the anterior, posterior, and medial aspects on radiographs using a validated computational algorithm.	6, 12, 24 weeks post surgery
Bridging Callus from CT	Cross-sectional image analysis, supported by 3-D rendering, to detect bony bridging at the anterior, posterior, and lateral aspects of the femur.	12 weeks post surgery
Fixation Failure	Assessed in terms of loss of alignment at 12 and 24 weeks post surgery	24 weeks post surgery
Hardware failure	Breakage of screw or plate	6, 12, 24 weeks post surgery

Collaborators and Investigators

• Sponsor: Legacy Biomechanics Laboratory
• Collaborators: Zimmer Biomet; University of Utah; Slocum Center for Orthopaedics, Eugene, OR
• Investigators: Principal Investigator: Michael Bottlang, PhD, Legacy Biomechanics Laboratory; Study Chair: Steven Madey, MD, Legacy Health System

Publications and helpful links

Helpful Links

• Orthopaedic Knowledge Online Article: Biomechanics and Use of Far Cortical Locking in Orthopaedic Trauma

Study record dates

Study Major Dates

• Study Start: April 1, 2011
• Primary Completion (Actual): May 1, 2012
• Study Completion (Actual): January 1, 2013

Study Registration Dates

• First Submitted: August 15, 2012
• First Submitted That Met QC Criteria: August 16, 2012
• First Posted (Estimate): August 17, 2012

Study Record Updates

• Last Update Posted (Estimate): January 29, 2013
• Last Update Submitted That Met QC Criteria: January 28, 2013
• Last Verified: January 1, 2013

More Information

Terms related to this study

• Keywords: Fracture Fixation; Locking Plate; Distal Femur Fracture; Far Cortical Locking; MotionLoc
• Additional Relevant MeSH Terms: Wounds and Injuries; Leg Injuries; Femoral Fractures; Fractures, Bone
• Other Study ID Numbers: MotionLoc Screw