Evaluation of the Results of Minimally Invasive Plate Osteosynthesis Using a Locking Plate in the Treatment of Distal Femur Fractures

Abstract

Introduction Distal femur fractures are serious injuries that can be difficult to treat, carry an unpredictable prognosis, and lead to long-term disability and morbidity. The introduction of minimally invasive plate osteosynthesis (MIPO) avoids direct exposure of the fracture site, improves fracture healing and decreases the incidence of complications. The aim of this study was to assess prospectively the early results of the treatment of supracondylar fractures of the femur using minimally invasive percutaneous osteosynthesis using a distal femoral locking plate. The study was a prospective study that included 20 adult patients who sustained distal femur fractures. Materials and methods The study was a prospective study that included 20 patients suffering from supracondylar fractures of the femur. All patients had fixation of the fracture using a distal femur locking plate (less invasive stabilization system (LISS)) in a minimally invasive technique using an anterolateral or direct lateral approach to the distal femur according to the fracture classification. The follow-up was done using the functional evaluation scale for distal femoral fractures as regards range of motion, deformation, pain, walking ability, and return to work. Results The mean age was 52.80 (19-80) years. The mean body mass index of the patients was 28.50, with a range of 23-43 kg/m². The mechanism of trauma was road traffic accidents (RTAs) in nine patients (45%) and falling from standing height in eleven patients (55%). Fractures were classified according to the Arbeitsgemeinschaft Osteosynthesefragen-Orthopedic Trauma Association (AO-OTA) classification. All patients were followed up for a period of six months and assessed in terms of knee range of motion, deformation, pain, walking ability, and return to work. The mean time of radiological union, in which bony trabeculae crossed the fracture gap, was 3.45 ± 0.79 months. The final results obtained were excellent in four patients (20%), good in nine patients (45%), fair in five patients (25%), and poor in two patients (10%). Complications encountered were knee stiffness (20%), superficial wound infection (10%), and shortening (15%). Conclusion LISS plating using the MIPO approach is useful in treating complex distal femoral fractures. Large studies from independent centers reporting long-term results are needed to further evaluate the role of LISS plating and the MIPO approach in the management of complex distal femoral fractures.

Keywords: distal femur fracture; liss; locking plate; minimally invasive surgery; mipo.

Figure 1. Lateral approach to the distal femur.

The patient is supine on the radiolucent table with a bump beneath the ipsilateral buttock. If there is no intra-articular extension, then a distal lateral incision is made starting just proximal to the lateral epicondyle and continuing distally. The incision is sharply continued through the iliotibial band and underlying vastus lateralis in line with their fibers. Dissection proceeds to bone without disruption of the overlying periosteum.

Figure 2. (A) and (B) Anterolateral approach to the distal femur.

If there is the intra-articular extension, then a longitudinal skin incision and a lateral parapatellar arthrotomy are done to allow direct visualization of the distal femoral articular surface for anatomic reduction and fixation.

Figure 3. Sub-muscular sliding of the LISS plate.

The LISS plate is inserted in a submuscular manner through the distal femur incision, spanning the metaphyseal fracture without direct exposure. Through an incision over the most proximal hole, a proximal connecting bolt was screwed into the proximal end of the plate. A Schanz pin has been inserted through the anterior thigh incision to aid in the reduction of the fracture at the metaphyseal-diaphyseal junction. LISS: less invasive stabilization system.

Figure 4. The external jig of the LISS.

Assembly of the external jig and the LISS plate. The connecting bolts are screwed through the jig into the distal and proximal parts of the plate to allow for the insertion of the screws using small incisions. LISS: less invasive stabilization system.

Figure 5. Proximal screws are inserted through multiple small incisions.

Postoperative photo demonstrating incisions after the implant has been placed. The lateral distal incision for the insertion of the plate and distal screws, and multiple small proximal incisions for the insertion of the proximal screws.

Figure 6. Intra-operative fluoroscopy images.

Images show that fluoroscopy is used intra-operatively to check the appropriate length and position of the plate and check the reduction and alignment of the fracture in both antero-posterior and lateral views.

Figure 7. Pre-operative x-rays.

X-rays show a comminuted (AO type C2) supra-condylar femur fracture with intra-articular extension.

Figure 8. Six months post-operative x-rays showing bridging callus formation.

Six months follow-up x-rays show bridging callus with satisfactory alignment in both antero-posterior and lateral views with no signs of implant failure.