Femoral Neck Fracture Fixation: An Intraoperative Masterclass

Welcome, fellows, to the operating theater. Today, we're tackling a critical injury: the femoral neck fracture. This is a common, often devastating, injury, particularly in the elderly, but also seen in high-energy trauma in younger patients. Our goal is to achieve stable fixation, preserve the femoral head, and restore function. We'll discuss both closed reduction and percutaneous fixation (CRPF) and open reduction and internal fixation (ORIF), adapting our strategy to the specific fracture pattern and patient factors.

Comprehensive Surgical Anatomy of the Proximal Femur

Before we even consider making an incision, a thorough understanding of the regional anatomy is paramount. The femoral neck is a critical region, rich in neurovascular structures and subject to significant biomechanical forces.

Osteology and Fracture Classification

The femoral head articulates with the acetabulum, forming the hip joint. The femoral neck connects the head to the femoral shaft via the greater and lesser trochanters. The calcar femorale, a dense vertical buttress of bone, extends from the posteromedial aspect of the femoral shaft into the neck, providing crucial structural support.

Fractures of the femoral neck are typically classified using:
* Garden Classification: Describes the degree of displacement and impaction.
* Garden I: Incomplete or impacted valgus fracture.
* Garden II: Complete, non-displaced fracture.
* Garden III: Complete, partially displaced fracture (often varus).
* Garden IV: Complete, fully displaced fracture, with the femoral head rotated.
* Pauwels Classification: Describes the angle of the fracture line relative to the horizontal, indicating stability and shear forces.
* Type I: <30 degrees (most stable).
* Type II: 30-50 degrees.
* Type III: >50 degrees (least stable, highest risk of nonunion).

Neurovascular Supply and Risks

The blood supply to the femoral head is notoriously tenuous and is the primary reason for the high rates of avascular necrosis (AVN) following displaced femoral neck fractures.
* Medial Femoral Circumflex Artery (MFCA): This is the dominant blood supply. It arises from the profunda femoris artery, passes posteriorly between the pectineus and iliopsoas, and then between the quadratus femoris and adductor magnus. It gives off retinacular arteries (superior, inferior, posterior) that ascend along the femoral neck within the joint capsule. Displaced fractures can shear these vessels.
* Lateral Femoral Circumflex Artery (LFCA): Also from the profunda femoris, it provides a lesser contribution, primarily to the anterior aspect of the neck.
* Artery of the Ligamentum Teres (Foveal Artery): A branch of the obturator artery, it supplies a small area of the femoral head, more significant in children.

Neurovascular Risks during Surgical Approach:
* Femoral Nerve: Lies anteriorly, lateral to the femoral artery and vein, within the femoral triangle. At risk during anterior approaches or excessive retraction.
* Sciatic Nerve: Lies posteriorly, deep to the gluteus maximus. At risk during posterior approaches or if the limb is excessively internally rotated during positioning, causing stretch.
* Lateral Femoral Cutaneous Nerve: Supplies sensation to the lateral thigh. Prone to injury with anterior or lateral incisions, leading to meralgia paresthetica.

Muscular Intervals and Approaches

Our choice of surgical approach (if ORIF is necessary) will dictate the muscular intervals we utilize.
* Anterior Approach (Smith-Petersen): Between the sartorius and tensor fascia lata (superficial interval), and between the rectus femoris and gluteus medius (deep interval). Provides excellent access to the anterior hip.
* Anterolateral Approach (Watson-Jones): Between the tensor fascia lata and gluteus medius. Less muscle detachment, good for anterior and superior aspects.
* Direct Lateral Approach (Hardinge): Splits the gluteus medius. Often used for total hip arthroplasty, can be adapted for fracture fixation.
* Posterior Approach (Kocher-Langenbeck): Between the gluteus maximus and gluteus medius. Detaches the short external rotators. Primarily used for posterior wall acetabular fractures or posterior hip dislocations, less common for femoral neck fixation unless direct visualization of the posterior neck is critical.

General Lower Extremity Anatomy Review (Peroneus Longus, Fibula, Interosseous Membrane, Tibia, Flexor Hallucis Longus)

Fellows, while our primary focus today is the proximal femur, it's crucial to maintain a holistic anatomical understanding of the entire lower extremity. The structures mentioned – Peroneus longus, Fibula, Interosseous membrane, Tibia, Flexor hallucis longus – are fundamental components of the lower leg.

• Tibia: The larger, medial bone of the lower leg, bearing most of the body's weight.
• Fibula: The thinner, lateral bone, primarily for muscle attachment and ankle stability.
• Interosseous Membrane: A strong fibrous sheet connecting the tibia and fibula, dividing the leg into anterior and posterior compartments and providing attachment for muscles.
• Peroneus Longus (Fibularis Longus): Originates from the head and upper two-thirds of the lateral surface of the fibula. It runs down the lateral leg, crosses the ankle posteriorly, and inserts into the medial cuneiform and base of the first metatarsal. It's a powerful evertor and plantarflexor of the foot. Innervated by the superficial peroneal nerve.
• Flexor Hallucis Longus: Originates from the posterior surface of the fibula and the interosseous membrane. Its tendon runs through the tarsal tunnel and inserts into the distal phalanx of the great toe. It is a strong flexor of the great toe and an ankle plantarflexor. Innervated by the tibial nerve.

Understanding these structures is vital for:
* Distal Neurovascular Assessment: Ensuring no iatrogenic injury to the peroneal or tibial nerves during positioning or traction.
* Associated Trauma: Recognizing concomitant lower leg injuries, which are not uncommon in high-energy mechanisms that cause femoral neck fractures.
* Postoperative Monitoring: Assessing for compartment syndrome or nerve palsies in the recovery phase.

Preoperative Planning & Patient Positioning

Gentlemen, success in femoral neck fracture fixation begins long before the incision. Meticulous preoperative planning and precise patient positioning are non-negotiable.

Templating and Fracture Assessment

1. Radiographic Evaluation: We'll review the AP pelvis, cross-table lateral hip, and often a true lateral (frog-leg) view. Assess fracture pattern, displacement (Garden, Pauwels classifications), comminution, and bone quality.
2. Implant Selection:
   • Cannulated Screws: Typically 3 parallel screws. Ideal for Garden I/II fractures, and sometimes Garden III/IV in younger patients with good bone stock. They provide compression and rotational stability.
   • Sliding Hip Screw (DHS): Less common for pure femoral neck fractures due to significant bone removal, but can be considered for certain unstable patterns or basal neck fractures. It provides controlled collapse and compression.
   • Arthroplasty: For elderly patients with displaced Garden III/IV fractures, especially those with pre-existing arthritis or poor bone quality, hemiarthroplasty or total hip arthroplasty may be a better option to ensure immediate weight-bearing and reduce reoperation rates. We will focus on internal fixation today.
3. Contralateral Hip Templating: Obtain an AP view of the contralateral hip for templating. This helps determine appropriate screw length and trajectory relative to the femoral head's size and neck angle.

Fluoroscopy Setup

The C-arm is our eyes in the OR for percutaneous fixation.
* Initial Setup: Position the C-arm on the contralateral side of the patient, allowing it to swing freely for AP and lateral views of the injured hip. Ensure sufficient space for the surgeon and assistants.
* Sterile Draping: The C-arm must be draped sterilely to allow manipulation during the case.
* Image Optimization: Confirm image quality, brightness, and contrast. The ability to obtain true AP and lateral views without moving the patient is paramount.

Patient Positioning: Supine on a Fracture Table

This is critical for achieving and maintaining reduction.
1. Preparation: The patient is brought into the OR and transferred carefully to the fracture table.
2. Perineal Post: A well-padded perineal post is inserted to provide counter-traction. Ensure it's positioned against the perineum, not the scrotum or labia, to prevent nerve compression or skin breakdown.
3. Uninjured Leg: The uninjured leg is placed in a well-padded traction boot, slightly abducted and flexed at the hip and knee, often resting on a separate leg support or a small stool to get it out of the C-arm's path.
4. Injured Leg: The injured leg is placed in a traction boot. We apply gentle, sustained longitudinal traction to disimpact the fracture and restore length.
5. Alignment: Ensure the patient's torso is straight on the table. The pelvis should be level.
6. Padding: Meticulous padding of all bony prominences (heels, fibular heads, sacrum, elbows) is essential to prevent pressure sores or nerve palsies. Pay particular attention to the common peroneal nerve at the fibular head.
7. Fluoroscopy Check: Confirm that AP and lateral views can be obtained without obstruction.

> SURGICAL WARNING: Inadequate padding, especially around the perineal post or fibular head, can lead to devastating nerve injuries (pudendal, sciatic, common peroneal) or pressure necrosis. Always double-check padding after positioning.

Step-by-Step Intraoperative Execution: The Operating Surgeon's Viewpoint

Alright, fellows, we're scrubbed in. Let's walk through this procedure, step by meticulous step.

Part 1: Closed Reduction and Percutaneous Fixation (CRPF) with Cannulated Screws

This is our preferred method for non-displaced or minimally displaced femoral neck fractures (Garden I/II, sometimes stable Garden III in young patients). The goal is anatomical reduction and stable internal fixation with minimal soft tissue disruption.

1. Reduction Maneuver

"Alright team, let's get a good reduction. This is the cornerstone of success here. Assistant, please apply gentle but firm longitudinal traction to the injured leg. Now, we're going to use a specific maneuver: traction, internal rotation, and slight abduction."

• Traction: The traction table already provides this. We're looking to disimpact the fracture.
• Internal Rotation: "Slowly internally rotate the leg, fellows. This helps correct the typical external rotation deformity of the distal fragment." We're aiming for approximately 15-20 degrees of internal rotation.
• Abduction: "A slight amount of abduction, perhaps 10-15 degrees, can help bring the femoral head into alignment."

2. Fluoroscopic Confirmation of Reduction

"Now, let's get our first fluoroscopic images. C-arm tech, please give me an AP view."

• AP View: "Excellent. On the AP, we're looking for restoration of the normal neck-shaft angle (typically 125-135 degrees) and the medial cortical alignment. See how the calcar femorale is now continuous? That's what we want. The Garden alignment index, which measures the angle of the trabeculae, should be between 160-180 degrees."
• Lateral View: "Now, swing the C-arm to a true lateral. This is critical for assessing sagittal plane alignment."
  • Perfect Lateral: "To get a true lateral, we often need to internally rotate the leg further, sometimes up to 30-45 degrees, until the lesser trochanter is no longer visible or is obscured by the femoral shaft. We want to see the femoral head and neck perfectly superimposed, without any overlap of the greater trochanter."
  • Assessment: "On the lateral, we're looking for the anterior and posterior cortices of the femoral neck to be perfectly aligned. No anterior or posterior gapping. The fracture should appear reduced. If there's any residual displacement, especially posterior angulation, we need to adjust our traction and rotation."

> SURGICAL WARNING: Inadequate reduction, particularly varus angulation or posterior displacement, significantly increases the risk of nonunion and avascular necrosis. Don't proceed until you have an anatomical or near-anatomical reduction on both AP and lateral views. If closed reduction fails, we must consider an open approach.

3. Incision and Guide Wire Placement

"Okay, the reduction looks good. Let's prepare for our guide wires. We'll typically use three parallel cannulated screws, aiming for an inverted triangle configuration for optimal stability."

• Skin Incisions: "I'll make three small stab incisions (approximately 1 cm each) on the lateral aspect of the proximal thigh, corresponding to our planned screw trajectories. These are typically just distal to the vastus lateralis ridge, in line with the femoral shaft axis."

  • "The most inferior screw will be positioned near the calcar femorale, providing crucial medial support. The superior screws will be more anterior and posterior in the femoral neck."
  • "Use a #15 blade, fellows, just through skin and subcutaneous tissue. Then use a small hemostat to spread down to the bone. We want to minimize soft tissue trauma."

• Guide Wire Insertion (Inferior Screw First):

  • "I'll start with the most inferior guide wire. This one is our workhorse for medial support."
  • "Place the trocar tip of the guide wire directly on the lateral cortex of the femur, approximately 1-2 cm distal to the lesser trochanter and slightly anterior to the mid-axis of the femur. This is our starting point."
  • "Now, visualize the trajectory. We want this wire to pass through the femoral neck, just superior to the calcar femorale, and end up in the subchondral bone of the femoral head. It should be parallel to the anterior cortex of the femoral neck on the lateral view and slightly inferior on the AP view."
  • "Using a T-handle, advance the guide wire slowly, under constant fluoroscopic guidance. Check AP and lateral frequently."
  • "On the AP view, ensure it's centered in the femoral neck. On the lateral, confirm it's in the middle of the neck, and not too anterior or posterior. We're aiming for the 'safe zone' of the femoral head."
  • "Advance the wire until its tip is approximately 5-10 mm from the articular surface of the femoral head. Do not penetrate the joint! This is a critical error."
  • "Once the first wire is in, leave the T-handle attached for stability."

4. Guide Wire Placement (Superior Screws)

"Now, for the superior wires. We'll use a guide wire aiming device or a triple drill guide to ensure parallelism and proper spacing. This helps create our inverted triangle."

• "Place the aiming device over the first guide wire. Position the remaining two sleeves for the superior wires. We want them spread out to maximize purchase in the femoral head."
• "Insert the second guide wire (often the most anterior one). Again, advance under fluoroscopy, checking AP and lateral views. Ensure it's parallel to the first wire and also within the subchondral bone."
• "Repeat for the third guide wire (posterior or superior-most). Confirm all three wires are parallel, well-spaced, and optimally positioned within the femoral head, avoiding joint penetration."

> SURGICAL WARNING: Malpositioning of guide wires is a common pitfall. If a wire is too anterior, posterior, superior, or inferior, or if it violates the joint, remove it and re-insert. Do not try to correct a poorly placed screw. Never use a single guide wire; three provide essential rotational stability.

5. Measuring, Drilling, Tapping, and Screw Insertion

"With our guide wires perfectly placed, we can now proceed to screw insertion."

• Measuring: "Using a depth gauge, measure the length of each guide wire. Subtract 5-10 mm from the measured length to ensure the screw tip remains subchondral and doesn't penetrate the joint. For example, if a wire measures 90mm, we'll choose an 80-85mm screw."
• Cannulated Drilling: "Select the appropriate cannulated drill bit. Advance it over each guide wire, drilling through the lateral cortex and femoral neck. Advance slowly, feeling for bone density changes. Do not drill into the femoral head. The drill should stop short of the fracture line or just past it, depending on the system."
  • "A common technique is to drill only the lateral cortex and proximal shaft to allow the screw threads to purchase well across the fracture."
• Cannulated Tapping (Optional, for Dense Bone): "In younger patients with dense bone, tapping may be necessary to prevent stripping of the screw threads or difficulty advancing the screw. Use the cannulated tap over the guide wire, again, just through the neck, not into the head."
• Screw Insertion:
  • "Select the appropriately sized cannulated screws. We're typically using fully threaded or partially threaded cancellous screws, depending on the surgeon's preference and fracture pattern. Partially threaded screws provide compression across the fracture."
  • "Advance each screw over its respective guide wire using the cannulated driver. Advance slowly, feeling for purchase. As the screw approaches the fracture, you'll feel compression across the fracture site. Tighten each screw sequentially to achieve even compression."
  • "The screw heads should sit flush with the lateral cortex. Avoid over-tightening, which can strip threads or cause iatrogenic fracture."
• Final Fluoroscopic Confirmation: "Once all screws are in, take final AP and lateral images. Confirm excellent reduction, proper screw length (subchondral, no joint penetration), and good spacing. Check for any signs of iatrogenic fracture."

6. Wound Closure

"Looks perfect, fellows. Now for closure."

• "Remove the guide wires. Apply gentle pressure to the stab incisions to control any bleeding."
• "Close the subcutaneous tissue with absorbable sutures (e.g., 2-0 Vicryl). Close the skin with non-absorbable sutures or staples (e.g., 3-0 Nylon or staples)."
• "Apply sterile dressings."

Part 2: Open Reduction and Internal Fixation (ORIF) with a Dynamic Hip Screw (DHS) or Multiple Screws

This approach is typically reserved for more complex fracture patterns, failed closed reduction, or specific basal neck fractures. We gain direct visualization of the fracture, allowing for more precise reduction and potentially stronger fixation. For the purpose of this masterclass, let's consider a scenario where we might use a DHS for a basal neck fracture, or multiple screws with direct visualization for a displaced Garden III/IV in a young patient.

1. Patient Positioning

"For an ORIF, we'll typically position the patient supine on a radiolucent table, not a fracture table, allowing us to manipulate the leg freely. The injured hip is draped free. We'll still need fluoroscopy, so ensure the C-arm can be brought in."

2. Surgical Approach and Incision

"For a femoral neck fracture requiring ORIF, a direct lateral approach (Hardinge) or an anterolateral approach (Watson-Jones) is often preferred, as it allows good access to the lateral femur and anterior neck."

• Incision (Hardinge): "I'll make a straight longitudinal incision, approximately 10-15 cm in length, centered over the greater trochanter, extending distally along the line of the femoral shaft. This will take us through skin and subcutaneous tissue."
• Fascia Lata: "Incise the fascia lata in line with the skin incision. Now we're looking at the vastus lateralis and the gluteus medius."
• Muscle Splitting (Hardinge): "We'll split the fibers of the gluteus medius and vastus lateralis. Use a blunt instrument or electrocautery on a low setting, carefully separating the fibers. This interval avoids significant muscle detachment."
  • > SURGICAL WARNING: Be mindful of the superior gluteal nerve which supplies the gluteus medius and minimus. Excessive proximal dissection or retraction can injure this nerve, leading to a Trendelenburg gait.
• Capsulotomy: "Once we've exposed the lateral aspect of the greater trochanter and the femoral neck, we'll perform a capsulotomy. A T-shaped or H-shaped capsulotomy provides excellent visualization of the femoral head and neck."
  • "Use a #10 blade to carefully incise the capsule. Be gentle, fellows, and protect the underlying retinacular vessels as much as possible, though some disruption is inevitable with an open approach."

3. Fracture Visualization and Reduction

"Now we have direct visualization of the fracture. This is where the beauty of ORIF comes in."

• Debridement: "Use a curette or rongeur to carefully debride any hematoma, fibrous tissue, or small bone fragments from the fracture site. This allows for better bone-to-bone contact."
• Direct Reduction: "Using bone clamps (e.g., pointed reduction clamps, Verbrugge clamps) or specialized manipulators, we'll directly reduce the fracture. Apply traction, rotation, and impaction as needed to achieve an anatomical reduction. We can visually confirm the alignment."
• Temporary Fixation: "Once reduced, we'll use K-wires (e.g., 2.0 mm) to temporarily stabilize the fracture. Place them strategically to hold the reduction while we prepare for definitive fixation. Confirm reduction with fluoroscopy if needed, but direct vision is our primary guide here."

4. Definitive Fixation (DHS or Multiple Screws)

Option A: Dynamic Hip Screw (DHS) (More common for basal neck or intertrochanteric fractures, but can be adapted)

• Reaming and Lag Screw Insertion:
  • "Identify the entry point for the lag screw, typically on the lateral cortex of the femur, 1-2 cm superior to the vastus lateralis ridge, aligned with the central axis of the femoral neck on AP view."
  • "Use a guide wire, aiming for the center of the femoral head, ending 1 cm from the articular surface. Confirm with fluoroscopy."
  • "Over-drill with a cannulated reamer to create the channel for the lag screw. Measure the depth."
  • "Insert the lag screw, ensuring it's centered in the femoral head. Advance it until the barrel is flush with the lateral cortex."
• Side Plate Application:
  • "Select the appropriate angle side plate (e.g., 135 degrees). Slide it over the lag screw barrel. Ensure it sits flush against the lateral femoral shaft."
  • "Secure the plate to the femoral shaft with cortical screws. Use a drill guide to ensure proper screw length and trajectory. Aim for bicortical purchase."
• Compression: "Apply compression across the fracture by turning the compression screw on the DHS plate. This draws the femoral head into the shaft, promoting stability."

Option B: Multiple Cannulated Screws (with direct visualization)

• "For a younger patient with a displaced fracture, we might still opt for multiple cannulated screws, but with the benefit of direct visualization."
• "With the fracture reduced and temporarily held by K-wires, we'll insert our guide wires under direct vision and fluoroscopy, ensuring optimal placement in the femoral head, away from the joint surface."
• "Proceed with measuring, drilling, and screw insertion as described in the CRPF section, ensuring good compression across the fracture."

5. Final Checks and Closure

"Excellent. The fixation is solid. Let's get final fluoroscopic images to confirm everything."

• **