Plate and Screw Fixation of Femoral Shaft Fractures: Principles, Biomechanics, and Surgical Techniques

INTRODUCTION TO FEMORAL SHAFT PLATING

Since the 1960s, the Arbeitsgemeinschaft für Osteosynthesefragen (AO) surgeons in Switzerland have revolutionized the management of diaphyseal fractures, utilizing either intramedullary fixation or compression plate fixation for almost all femoral shaft fractures. While intramedullary nailing remains the gold standard for the majority of isolated diaphyseal femur fractures, plate and screw fixation retains highly specific, indispensable indications in modern orthopedic traumatology.

Historically, the most accurate reduction of comminuted fractures of the femoral shaft was obtained with interfragmentary compression combined with rigid plate and screw fixation. This treatment allowed early motion and restored excellent joint function. However, early iterations of this technique required extensive periosteal stripping, leading to unacceptable complication rates. Historical literature reported infection rates of 2% to 5%, failure of fixation between 6% and 10%, and delayed union in up to 19% of cases.

As noted by Magerl et al., complications were significantly more common if the primary objective of surgery—rigid internal fixation with absolute stability and interfragmentary compression—was not achieved. Conversely, when this objective was successfully met, complications were remarkably few. Today, the paradigm has shifted from absolute rigidity to biological osteosynthesis, emphasizing indirect reduction, preservation of the soft tissue envelope, and the use of Minimally Invasive Plate Osteosynthesis (MIPO).

INDICATIONS AND CONTRAINDICATIONS

While antegrade or retrograde intramedullary nailing is the workhorse for femoral shaft fractures, plating is specifically indicated in complex clinical scenarios where nailing is contraindicated or technically prohibitive.

Primary Indications

• Polytrauma and Damage Control Orthopedics (DCO): Femoral plating is highly recommended in patients with blunt polytrauma. Rapid stabilization via plating minimizes the systemic inflammatory response syndrome (SIRS) and avoids the pulmonary complications (e.g., fat embolism syndrome) occasionally associated with intramedullary reaming.
• Ipsilateral Femoral Neck and Shaft Fractures: Plating the shaft allows for unhindered, optimal fixation of the femoral neck (e.g., with cannulated screws or a sliding hip screw) without the spatial conflicts introduced by a reconstruction nail.
• Vascular Injuries: Fractures associated with arterial injuries requiring repair (e.g., superficial femoral artery lacerations) benefit from plating, as the surgical approach allows simultaneous access for vascular repair and skeletal stabilization.
• Unstable Spinal Injuries: In patients who cannot be safely positioned on a fracture table or placed in the lateral decubitus position, supine plating offers a safe alternative.
• Anatomical Constraints: Patients with excessively narrow medullary canals, severe pre-existing deformities (e.g., Paget's disease, prior malunion), or retained hardware (e.g., hip or knee arthroplasty stems) that preclude intramedullary nailing.

Contraindications

• Severe osteopenia where screw purchase is inadequate (unless utilizing modern locking plate technology with meticulous technique).
• Active infection at the surgical site.
• Extensive soft tissue compromise over the lateral thigh (e.g., severe Morel-Lavallée lesion or open degloving), which may necessitate external fixation instead.

Clinical Pearl: In polytrauma patients, Riemer et al. reported excellent results using stainless steel femoral plating in 141 fractures caused by blunt trauma (one-third open). The average time to union was 18 weeks, with 99% of patients regaining full extension and at least 130 degrees of knee flexion.

BIOMECHANICAL PRINCIPLES OF FIXATION

The success of plate and screw fixation in the femur hinges on a profound understanding of biomechanics and the biological environment of the fracture. Plating of femoral shaft fractures requires immense experience and judgment; misuse of this method produces more poor results than any other technique.

Absolute vs. Relative Stability

• Absolute Stability: Indicated for simple fracture patterns (e.g., transverse, short oblique, or spiral fractures; AO/OTA Type A). The goal is anatomical reduction and interfragmentary compression using lag screws and a neutralization plate, or a dynamic compression plate (DCP). This construct abolishes interfragmentary strain, leading to primary (osteonal) bone healing without visible callus formation.
• Relative Stability (Bridge Plating): Indicated for comminuted or multi-fragmentary fractures (AO/OTA Type B and C). The objective is to restore length, alignment, and rotation (LAR) without disturbing the fracture hematoma. A long plate is used to span the zone of comminution. This construct allows micro-motion at the fracture site, stimulating secondary bone healing via robust callus formation.

Surgical Warning: Attempting to achieve absolute stability in a highly comminuted fracture requires devastating soft tissue stripping. This devascularizes the intermediate fragments, leading to a high risk of nonunion, implant fatigue, and catastrophic failure.

The Role of Medial Cortical Support

The femur is subjected to massive eccentric loading, with compressive forces acting on the medial cortex and tensile forces on the lateral cortex. If the medial cortex is comminuted and lacks bony contact, a laterally applied plate is subjected to severe cantilever bending forces.

Historically, Rüedi and Lüscher recommended the routine application of a medial bone graft in all comminuted fractures fixed with AO plates, or if rigid fixation was not obtained. Today, while routine autografting has decreased due to biological plating techniques, the principle remains: if a massive medial void exists, the plate will eventually fail due to fatigue unless the fracture heals rapidly. Modern solutions include using longer, stronger plates (e.g., 4.5mm broad locking compression plates), overlapping screw fixation, or delayed bone grafting if callus fails to form.

PREOPERATIVE PLANNING

Meticulous preoperative planning is mandatory to avoid intraoperative complications and ensure biomechanical success.

1. Imaging: Obtain orthogonal (AP and lateral) radiographs of the entire femur, including the hip and knee joints, to rule out ipsilateral femoral neck fractures or coronal shear fractures of the distal femur.
2. Templating: Utilize digital templating to determine plate length and screw positions. For bridge plating, the plate should be long enough to allow a plate span ratio (plate length to fracture length) of >3.0, and a screw density (number of screws inserted divided by the number of plate holes) of <0.5 to optimize construct elasticity.
3. Implant Selection: A 4.5mm broad plate is standard for the femoral shaft. Locking Compression Plates (LCP) are preferred in osteoporotic bone or short segment fixations, whereas conventional plates (LC-DCP) are highly effective for standard diaphyseal compression.

PATIENT POSITIONING AND PREPARATION

1. Positioning: The patient is typically placed supine on a radiolucent flat table. A bump is placed under the ipsilateral hip to internally rotate the leg, bringing the patella forward and neutralizing the natural external rotation of the lower extremity.
2. Preparation: The entire lower extremity from the iliac crest to the toes is prepped and draped free. This allows for intraoperative assessment of length, alignment, and rotation, and facilitates manipulation of the limb for indirect reduction.
3. Fluoroscopy: The C-arm is positioned on the contralateral side, ensuring unhindered AP and lateral imaging of the entire femur.

SURGICAL APPROACHES

The Standard Lateral Approach

The lateral approach to the femur provides extensile access to the entire diaphysis.
1. Incision: A longitudinal incision is made along the lateral aspect of the thigh, centered over the fracture or extending as needed based on preoperative templating.
2. Superficial Dissection: The subcutaneous tissue is divided to expose the iliotibial (IT) band. The IT band is incised longitudinally in line with its fibers.
3. Deep Dissection: The vastus lateralis is identified. The approach can be developed either transvastus (splitting the muscle belly) or subvastus (elevating the muscle off the lateral intermuscular septum). The subvastus approach is preferred as it minimizes muscle damage.
4. Vascular Management: As the vastus lateralis is elevated anteriorly off the linea aspera, the perforating branches of the profunda femoris artery are encountered. These must be meticulously identified, ligated, or cauterized to prevent severe postoperative hematoma.

Minimally Invasive Plate Osteosynthesis (MIPO)

Current minimally invasive plating techniques have the distinct advantage of minimizing surgical trauma, preserving the periosteal blood supply, and providing stable fixation that typically requires no adjuvant bracing.
1. Incisions: Proximal and distal mini-incisions are made corresponding to the ends of the planned plate.
2. Tunneling: An extra-periosteal, submuscular tunnel is created deep to the vastus lateralis using a tunneling instrument or the plate itself.
3. Plate Insertion: The plate is slid from proximal to distal (or vice versa) across the fracture zone.
4. Reduction: Indirect reduction techniques are employed before securing the plate.

STEP-BY-STEP SURGICAL TECHNIQUE

Technique for Simple Fractures (Absolute Stability)

1. Reduction: The fracture is exposed and anatomically reduced using bone reduction forceps (e.g., Weber clamps).
2. Interfragmentary Compression: If the fracture geometry allows (e.g., oblique fracture), a 4.5mm cortical lag screw is placed perpendicular to the fracture plane to achieve absolute interfragmentary compression.
3. Neutralization Plating: A 4.5mm broad plate is contoured to the lateral bow of the femur and applied to neutralize torsional, bending, and shear forces. At least 8 to 10 cortices of fixation are required proximal and distal to the fracture.

Technique for Comminuted Fractures (Bridge Plating)

Excellent results have been obtained with plating of comminuted shaft fractures without medial bone grafting when indirect reduction of intermediate fragments, preservation of soft tissue attachments to bone (especially medially), and final compression have been obtained.
1. Indirect Reduction: Length is restored using manual traction, a femoral distractor, or a fracture table. Alignment and rotation are checked clinically and fluoroscopically. The intermediate comminuted fragments are left untouched to preserve their vascularity.
2. Plate Application: A long 4.5mm broad plate (often 10 to 14 holes) is slid submuscularly across the fracture zone.
3. Fixation: The plate is secured proximally and distally. In bridge plating, it is crucial to leave 2 to 3 plate holes empty directly over the fracture site to increase the working length of the plate, thereby reducing strain at the fracture gap and promoting robust callus formation.
4. Locking Screws: If using an LCP, conventional cortical screws are used first to pull the plate to the bone (if desired), followed by locking screws to create a fixed-angle construct.

Pitfall: Placing screws too close to the fracture gap in a comminuted fracture creates a short working length. This concentrates stress on a small segment of the plate, drastically increasing the risk of premature fatigue failure before the fracture can heal.

COMPLICATIONS AND MANAGEMENT

Despite advances in technique, plating of the femoral shaft carries inherent risks that the surgeon must be prepared to manage.

Implant Failure and Nonunion

Riemer et al. reported a 7% implant failure rate (seven plates, three screws) in their series, often associated with delayed union in elderly patients or those with severe comminution.
* Etiology: Failure is almost always mechanical, resulting from a race between bone healing and implant fatigue. If the medial cortex is deficient and the fracture does not heal rapidly, the lateral plate will undergo cyclic bending and eventually break.
* Management: Treatment of a broken plate or nonunion requires revision surgery. This typically involves removal of hardware, opening the medullary canal, and converting to a statically locked intramedullary nail. If re-plating is chosen, a longer plate, rigid compression, and autologous iliac crest bone grafting (to address the medial void) are mandatory.

Infection

Historically reported at 2% to 5%, deep infection is a devastating complication.
* Prevention: Meticulous soft tissue handling, minimizing periosteal stripping, copious irrigation, and prophylactic antibiotics are essential.
* Management: Acute infections require aggressive surgical debridement, irrigation, and targeted intravenous antibiotics. If the plate is providing stable fixation, it should be retained until the fracture heals. If the fixation is loose, the hardware must be removed, the canal reamed and irrigated, and stabilization achieved via external fixation or an antibiotic-coated intramedullary nail.

POSTOPERATIVE PROTOCOL AND REHABILITATION

The postoperative regimen is dictated by the fracture pattern, the quality of bone, and the stability of the construct.

1. Early Mobilization: One of the primary benefits of stable internal fixation is the ability to initiate early motion. Patients are encouraged to begin active and active-assisted range of motion (ROM) exercises for the hip and knee on postoperative day one. This prevents arthrofibrosis and promotes gliding of the vastus lateralis over the plate.
2. Weight-Bearing Status:
   • Absolute Stability Constructs: For simple fractures with rigid compression, partial weight-bearing (toe-touch to 20 kg) is typically allowed immediately, advancing to full weight-bearing at 6 to 8 weeks based on radiographic evidence of healing.
   • Bridge Plating Constructs: For comminuted fractures treated with relative stability, weight-bearing is often restricted to toe-touch for the first 6 weeks to protect the plate from fatigue failure, advancing only when bridging callus is visible on orthogonal radiographs.
3. Thromboprophylaxis: Standard deep vein thrombosis (DVT) prophylaxis (e.g., low molecular weight heparin) is administered according to institutional polytrauma protocols.

CONCLUSION

Plate and screw fixation of the femoral shaft has evolved significantly from the era of rigid, devascularizing anatomical reduction to the modern era of biological osteosynthesis. While intramedullary nailing remains the primary treatment for most diaphyseal femur fractures, plating is an indispensable technique for polytrauma patients, those with ipsilateral femoral neck fractures, and cases involving vascular compromise. By adhering to strict biomechanical principles—utilizing absolute stability for simple fractures and relative stability via MIPO for comminuted fractures—orthopedic surgeons can achieve high union rates, restore excellent limb function, and minimize the historical complications associated with femoral plating.