The FLiP Study, a Pilot Cluster Randomized Trial

The primary objective of this pilot trial is to assess the feasibility of a definitive trial to determine the effect of lateral patient positioning versus supine positioning with fracture table use for reamed antegrade intramedullary fixation of femur fractures.

Femoral shaft fractures typically occur alongside other complex, high-energy injuries in the poly-traumatized patient. Femur fractures can cause extensive bleeding and surrounding muscle injury, and have a high global burden; occurring at a rate between 14 and 42.5 /100,000 person years, with approximately 1 in 10 road traffic accidents worldwide resulting in a femoral shaft fracture requiring surgery. Additionally, there is significant disparity in the burden of diaphyseal femur fractures, with 91% occurring in lower middle-class income countries, and the majority affecting younger males.

To help mitigate the effects of ongoing pain, blood-loss, worsening inflammation from unstable fracture ends, femoral shaft fractures require urgent management using either an early total-care or damage-control orthopaedics approach. Associated injuries, markers of resuscitation, and overall patient stability guide operative decision making and the timing of surgical intervention. Definitive internal fixation using reamed, locked intramedullary nailing (IMN) has become the standard of care in an adequately resuscitated patient, as it provides fracture stability while facilitating nursing care and patient mobilization. Multiple femoral IMN techniques exist; however, most femoral shaft fractures can be treated with an antegrade nail using either supine (fracture table) or lateral (free-leg drape) positioning.

Femoral Malrotation is a Common and Significant Complication

Despite the adoption of femoral IMN, patient-reported function following femur fracture fixation varies widely. Incorrect positioning of the fracture fragments by more than 15° relative to the native limb rotation (femoral malrotation) is associated with poor functional recovery, low health-related quality of life, gait abnormalities, difficulty with stairs, and delayed return to pre-injury activity. Significant femoral malrotation (\>15°) occurs in up to 55% of patients following femoral shaft fracture IMN, as measured by post-operative computer tomography (CT) scans. Numerous intraoperative assessments have been used to judge rotation, including cortical diameter, lesser trochanter profile and others; though none are easily reproducible or reliable. The preferred technique by surgeons is the lesser trochanter profile, but this method requires a true anteroposterior view of the pelvis, which can be challenging to obtain with the fracture table in place.

A Lack of Consensus On Operative Table and Patient Positioning While the orthopaedic surgery community agrees that femoral shaft fractures should be treated with IMN, there is a lack of agreement on whether the patient should be placed in the supine position on fracture table (SFT) or in the lateral position on a standard radiolucent operating table (LRT). Our research team recently conducted a survey of the Canadian Orthopaedic Association membership and found a clear divide on patient positioning, with 56% of respondents using supine position on fracture table and 44% using a form of lateral positioning.

A recent comprehensive review identified only three studies on this specific topic. The best existing evidence of the previous literature comes from a prospective randomized trial led by Stephen et al. The authors described that supine positioning without use of fracture table yielded better post-operative rotation than patients treated with a fracture table. However, this study did not assess the utility of lateral positioning, which is more commonly used in isolated femoral shaft fractures. Moreover, the study was unable to associate malrotation with patient important outcomes or gait abnormalities. This clearly leaves much uncertainty surrounding optimal patient positioning during the definitive treatment of these critical injuries.

Proponents of positioning femoral shaft fracture patients using SFT argue that the fracture table provides a constant traction force to stabilize the fractured limb and allows for better intraoperative imaging. This arguably allows surgeons to reduce operative time and minimize the need for surgical assistants. However, possible downsides of this technique include the need for more invasive surgical adjuncts if there is ongoing difficulty with fracture reduction. Furthermore, constant and prolonged traction poses known risks to neurovascular structures associated with the central post, and may overpower feedback from the natural resting tone of the surrounding thigh musculature, possibly leading to a higher incidence of fixation in a malrotated position. Additionally, fracture tables are expensive and require additional setup in the operating room prior to the procedure.

Orthopedic surgeons who prefer the LRT believe it offers improved access to the start point for IMN as well as to the rest of the femur for manipulation, resulting in a better reduction of the fractured limb. With the entire limb free of traction, the thigh sits in a relatively adducted position at rest and the soft tissues tend to fall away from the operative field. The fracture fragments can be readily accessed and freely manipulated, with muscles returning to their resting tension as alignment is restored. It is believed that this leads to leads to improved limb alignment and less malrotation. Furthermore, there may be benefits to the overall patient, many of whom have other severe injuries that may also be impacted by intraoperative positioning. A recent cohort study, which was adjusted for associated injuries, found that patients treated using the LRT had shorter ICU stays and reduced number of days on a ventilator, indicating that there may be a protective effect from a respiratory standpoint. Additionally, the standard operating room table is readily available, less expense, and does not require additional setup prior to the procedure. However, there are concerns that lateral positioning may lead to longer operative times as additional positioning aids and reduction maneuvers may be required. Specifically, patients receiving delayed fixation may pose a challenge due to increased muscle shortening and tone that may be difficult to overcome with manual traction alone.

Limited previous studies align with biomechanical principles, and suggest that lateral positioning holds potential to reduce the incidence of femoral malrotation and avoid complications associated with the use of a fracture table; leading to improved patient function. Addressing malrotation by using the LRT may represent a simple and reproducible intervention that may improve quality of life for the patient.

NEED FOR A TRIAL Currently, the choice between the two techniques is dependent on surgeon preference, with very limited evidence to guide decision making. A large definitive trial is needed to answer this question and allow orthopaedic surgeons to make an evidence-based decision on how to treat patients with femoral shaft fractures, while reducing the incidence of malrotation and improving patient outcomes. Prior to embarking on a large definitive cluster randomized crossover trial (CRXO), a pilot study is needed to demonstrate feasibility. A pilot study would assess areas of uncertainty that may impact feasibility to perform the definitive trial, including achieving adequate recruitment, adherence to protocol, and minimal contamination.

Eligibility Criteria:
Inclusion Criteria:

1. Adult aged 18 years or older
2. Mid shaft (Diaphyseal) femur fracture appropriate for antegrade fixation
3. Surgery performed by participating surgeon or delegate
4. Provision of informed consent
5. Enrolled within 3 weeks of femoral shaft fixation

Exclusion Criteria:

• 1. Ipsilateral tibial fracture 2. Bilateral femur fracture 3. Ipsilateral femoral neck fracture 4. Ipsilateral acetabular fracture 5. Periprosthetic fracture 6. Pathologic fracture 7. Previous external fixation of femoral shaft fracture 8. Inability to be positioned in lateral decubitus because of a concomitant injury 9. Pregnancy (due to decubitus positioning) 10. Incarceration 11. Expected injury survival of less than 6 months 12. Terminal illness with expected survival of less than 6 months (expected follow up of study) 13. Inability to provide informed consent (e.g. cognitive disability, language barrier, significant delirium or dementia) 14. Currently involved in study that does not permit co-enrolment 15. Likely problems, in the judgment of study personnel, with maintaining follow-up with the patient