Distal Femoral Fractures

1. Clinical Overview

Summary

Distal femoral fractures involve the distal metaphyseal and epiphyseal regions of the femur, typically within 15cm of the knee joint. These injuries represent 4-7% of all femoral fractures and are among the most challenging fractures in orthopaedic trauma due to their proximity to the knee joint, complex anatomy, and high complication rates. [1,2] The injury pattern demonstrates a distinct bimodal age distribution: high-energy trauma in young adults (motor vehicle accidents, falls from height) and low-energy falls in elderly patients with osteoporosis. [3] An increasing proportion occurs as periprosthetic fractures around total knee replacements, reflecting the aging population and prevalence of arthroplasty. [4]

The anatomical complexity of the distal femur, combined with deforming muscular forces and proximity to neurovascular structures, makes these fractures technically demanding to manage. The popliteal artery is particularly vulnerable due to anatomical tethering at the adductor hiatus, and arterial injury occurs in 2-3% of displaced fractures. [5] Surgical management typically involves either lateral locked plating systems or retrograde intramedullary nailing, with fixation choice dependent on fracture pattern, bone quality, and presence of arthroplasty. [6,7]

Despite advances in fixation techniques, outcomes remain variable with non-union rates of 5-10%, malunion rates of 10-20%, and knee stiffness developing in up to 50% of patients. [8] Post-traumatic arthritis develops in 20-40% of intra-articular fractures despite anatomical reduction, emphasizing the importance of articular restoration and early mobilization. [9]

Key Facts

Anatomical Considerations:

• The Metaphyseal Flare: The distal femur transitions from a cylindrical shaft to a broad metaphyseal region, creating a stress concentration zone particularly vulnerable in osteoporotic bone.
• Condylar Architecture: The medial and lateral femoral condyles have different radii of curvature, with the lateral condyle projecting more anteriorly - relevant for plate contouring and screw placement.
• Articular Surface: The distal femoral articular cartilage is weight-bearing and any step-off > 2mm significantly increases arthritis risk. [10]

Deforming Forces:

• Gastrocnemius: Originates from the posterior femoral condyles and pulls the distal fragment into extension/recurvatum, creating a sharp posterior spike that threatens the popliteal neurovascular bundle.
• Adductor Magnus: Inserts on the adductor tubercle and pulls the proximal fragment into varus and adduction.
• Quadriceps: Creates shortening and proximal displacement.
• Hamstrings: Contribute to shortening and posterior angulation.

Hoffa Fracture: A unique coronal plane fracture of the femoral condyle, occurring in the sagittal axis like slicing a loaf of bread. It represents 8.7% of distal femur fractures and is easily missed on standard radiographs. [11] The lateral condyle is involved in 85% of cases due to valgus loading mechanisms. These fractures are inherently unstable due to muscle pull and require separate screw fixation perpendicular to the fracture plane.

Periprosthetic Fractures: Fractures occurring around total knee arthroplasty (TKA) components are increasing exponentially, with incidence of 0.6-2.5% following primary TKA and up to 5.5% after revision TKA. [12] The presence of a femoral component fundamentally alters fracture pattern, bone quality, and treatment options. The Rorabeck-Lewis classification stratifies these based on displacement and implant stability, guiding management decisions.

Clinical Pearls

"Pulse and Perfusion Protocol": The popliteal artery is anatomically tethered at the adductor hiatus proximally and by the geniculate branches distally, making it vulnerable to stretch injury in displaced fractures. Always document bilateral ankle-brachial indices (ABI). Any ABI less than 0.9 or asymmetry > 0.15 mandates CT angiography. [5] Vascular injury is a limb-threatening emergency requiring urgent reduction and surgical exploration.

"Spanning External Fixation - Damage Control Principle": In polytrauma patients, open fractures, or severe soft tissue injury, immediate definitive fixation risks catastrophic infection and wound complications. Apply a spanning external fixator (femur to tibia across the knee joint) as damage control, allowing soft tissue recovery over 7-14 days before definitive fixation. This reduces infection rates from 30% to 5-8%. [13]

"The Hoffa Search": On every distal femur fracture CT scan, meticulously scroll through coronal reconstructions looking for a coronal plane split. Hoffa fractures are notoriously missed on sagittal and axial views. Missing this fragment leads to persistent instability and fixation failure. Lateral Hoffa fragments require posterior-to-anterior or anterior-to-posterior screw fixation, placed perpendicular to the fracture line. [11]

"Double Plating Indication": For highly comminuted AO/OTA 33-C3 fractures with significant metaphyseal bone loss, a lateral locked plate alone may fail due to asymmetric loading. Consider dual plating (lateral locked plate + medial plate) to create a symmetric construct, particularly in young high-demand patients. Recent biomechanical studies demonstrate 40% increase in construct stiffness. [14]

"MIPO Technique": Minimally Invasive Plate Osteosynthesis (MIPO) using submuscular plate insertion preserves periosteal blood supply and fracture hematoma. Create a small distal incision for articular reduction, then tunnel the plate proximally beneath vastus lateralis. Use indirect reduction techniques and avoid extensive soft tissue stripping. This reduces non-union risk compared to open techniques. [15]

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2. Epidemiology

Demographics

Incidence: Distal femoral fractures occur at a rate of 37 per 100,000 person-years in the general population, representing 4-7% of all femoral fractures and 0.4% of all fractures. [1,2] The incidence demonstrates a bimodal distribution across age groups with distinct injury mechanisms.

Age Distribution:

• First Peak: Males aged 15-35 years (high-energy trauma)
• Second Peak: Females aged 65-85 years (low-energy falls)
• Periprosthetic Fractures: Mean age 75 years, predominantly female (3:1 ratio) [4]

Gender: Overall male-to-female ratio is approximately 1:1, but varies by age:

• Young cohort (less than 50 years): Male predominance 3:1
• Elderly cohort (> 65 years): Female predominance 2:1 (osteoporosis-related)

Geographic and Temporal Trends: The incidence of distal femoral fractures is rising, particularly in elderly populations due to:

• Aging demographics (projected 20% increase by 2030)
• Increased prevalence of total knee arthroplasty (periprosthetic fractures increasing 6% annually)
• Higher activity levels in elderly maintaining independent mobility [3]

Mechanism of Injury

High-Energy Mechanisms (Young Patients):

• Motor Vehicle Accidents (45%): Dashboard injuries creating axial load with knee flexion, driving femoral condyles proximally into shaft
• Motorcycle Accidents (25%): Direct lateral blow to flexed knee
• Falls from Height (20%): Axial loading with varying degrees of knee flexion
• Pedestrian vs Vehicle (10%): Direct blow to distal thigh/knee region

Low-Energy Mechanisms (Elderly Patients):

• Simple Fall from Standing (70%): Most common in osteoporotic bone
• Minor Twist or Stumble (20%): Spiral fracture pattern
• Periprosthetic (10%): Fracture around TKA component, often minimal trauma

Biomechanical Factors:

• Osteoporosis: Bone mineral density T-score < -2.5 increases fracture risk 5-fold
• Notch Effect: The intercondylar notch creates a stress riser
• TKA Stress Shielding: Stiff femoral component creates stress concentration at bone-prosthesis junction [12]

Risk Factors

Patient-Related:

• Advanced age (> 65 years)
• Female gender (osteoporosis)
• Osteoporosis/osteopenia (T-score < -1.0)
• Neurological conditions (Parkinson's disease, stroke) increasing fall risk
• Vitamin D deficiency
• Chronic corticosteroid use
• Rheumatoid arthritis
• Renal osteodystrophy

Implant-Related (Periprosthetic):

• Presence of total knee arthroplasty
• Long-stemmed femoral component (stress concentration at tip)
• Anterior femoral notching during TKA (27% increase in fracture risk) [16]
• Revision TKA (3x higher risk than primary)
• Loose femoral component

Activity-Related:

• High-energy sports (motorcycling, skiing)
• Occupational hazards (construction, height work)
• High-impact activities in elderly with poor bone quality

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3. Pathophysiology

Anatomical Considerations

Osseous Anatomy:

The distal femur extends from the metaphyseal-diaphyseal junction (approximately 15cm proximal to the joint line) to the articular surface of the femoral condyles. Key anatomical features include:

Metaphyseal Flare: The femoral shaft (diameter 25-30mm) expands to the wide metaphyseal region (diameter 70-80mm at condylar level), creating a funnel-shaped transition zone. This geometry creates:

• Stress concentration in the supracondylar region
• Thin cortical bone with increased trabecular bone ratio
• Vulnerability in osteoporotic bone where trabecular microarchitecture is compromised

Femoral Condyles:

• Medial Condyle: Larger, projects more distally, bears greater axial load
• Lateral Condyle: Smaller, projects more anteriorly, has shallower trochlear groove
• Intercondylar Notch: Creates a cruciate ligament housing and mechanical stress riser
• Condylopatellar Groove: Anterior articular surface for patella tracking

Blood Supply:

The distal femur receives blood supply from:

• Nutrient Artery: Enters at mid-diaphysis, supplies proximal fragment
• Descending Genicular Artery: Branch of superficial femoral artery, supplies distal metaphysis
• Genicular Anastomosis: Five geniculate arteries (superior/inferior medial/lateral, middle) form rich periarticular network
• Metaphyseal Watershed Zone: Relative hypovascularity in supracondylar region contributes to non-union risk [17]

Soft Tissue Anatomy:

Neurovascular Bundle: The popliteal vessels course through the posterior compartment, tethered at two critical points:

• Proximally: Adductor hiatus (hiatus of adductor magnus)
• Distally: Soleal arcade (as vessels enter posterior tibial compartment)

This tethering creates vulnerability in displaced fractures, particularly with posterior displacement or recurvatum where the sharp proximal edge of the distal fragment can impale or stretch the artery. The popliteal vein is larger and thinner-walled, making it even more vulnerable to injury than the artery.

Common Peroneal Nerve: Wraps around the fibular neck (8cm distal to fracture site) but can be injured by:

• Extreme varus deformity creating traction
• Compartment syndrome affecting the lateral compartment
• Iatrogenic injury during fibular plating if dual plating performed

Muscular Envelope:

Quadriceps Mechanism:

• Rectus Femoris: Crosses hip and knee, creates shortening force
• Vastus Medialis/Lateralis/Intermedius: Adhere to femoral shaft, stripped by fracture hematoma, create vascular compromise

Gastrocnemius:

• Medial/Lateral Heads: Origin from posterior femoral condyles
• Deforming Force: Pulls distal fragment into extension (recurvatum) via posterior insertion
• Clinical Significance: Creates the classic "spike" of bone threatening popliteal vessels

Adductor Magnus:

• Inserts on medial supracondylar ridge and adductor tubercle
• Pulls proximal shaft into varus and adduction
• Creates characteristic varus deformity seen on AP radiographs

Classification Systems

AO/OTA Classification (33-A, B, C):

The Arbeitsgemeinschaft für Osteosynthesefragen (AO) / Orthopaedic Trauma Association (OTA) system is the most widely used, based on articular involvement and fracture complexity:

Type A - Extra-articular Fractures (33-A): The fracture line does not extend into the knee joint. Represents 45% of distal femoral fractures.

• 33-A1: Simple metaphyseal (spiral or oblique)

  • "A1.1: Avulsion of lateral epicondyle"
  • "A1.2: Oblique supracondylar"
  • "A1.3: Transverse supracondylar"

• 33-A2: Metaphyseal wedge (butterfly fragment)

  • "A2.1: Intact medial wedge"
  • "A2.2: Intact lateral wedge"
  • "A2.3: Medial and lateral wedge"

• 33-A3: Complex metaphyseal (comminuted)

  • "A3.1: Two intermediate fragments"
  • "A3.2: Three intermediate fragments"
  • "A3.3: >Three intermediate fragments"

Type B - Partial Articular Fractures (33-B): The fracture enters the joint but maintains continuity between part of the articular surface and the shaft. Represents 20% of cases.

• 33-B1: Sagittal lateral condyle (Hoffa fracture variant)

  • "B1.1: Lateral condyle, simple"
  • "B1.2: Lateral condyle, depression"
  • "B1.3: Lateral condyle, comminuted"

• 33-B2: Sagittal medial condyle

  • "B2.1: Medial condyle, simple"
  • "B2.2: Medial condyle, depression"
  • "B2.3: Medial condyle, comminuted"

• 33-B3: Frontal (coronal plane - classic Hoffa)

  • "B3.1: Lateral condyle (most common)"
  • "B3.2: Medial condyle"
  • "B3.3: Both condyles (dual Hoffa)"

Type C - Complete Articular Fractures (33-C): Both condyles are separated from the femoral shaft and each other. Represents 35% of cases and most challenging to treat.

• 33-C1: Simple articular, simple metaphyseal

  • "C1.1: Minimal intercondylar separation"
  • "C1.2: T-type configuration"
  • "C1.3: Y-type configuration"

• 33-C2: Simple articular, complex metaphyseal

  • "C2.1: With one intermediate fragment"
  • "C2.2: With several intermediate fragments"
  • "C2.3: Extending into diaphysis"

• 33-C3: Complex articular (most severe)

  • "C3.1: Comminuted, limited to metaphyseal region"
  • "C3.2: Comminuted, extending to diaphysis"
  • "C3.3: Multifragmentary articular and metaphyseal"

Rorabeck-Lewis Classification (Periprosthetic):

Specifically for fractures around total knee arthroplasty femoral components, based on displacement and implant stability: [4]

Type I: Non-displaced fracture, prosthesis stable

• Treatment: Non-operative (hinged brace) or minimal fixation
• Prognosis: Good, 85% union rate

Type II: Displaced fracture, prosthesis stable (MOST COMMON - 65% of cases)

• Treatment: ORIF with lateral locked plate ± retrograde nail if canal available
• Prognosis: Fair, 75% union rate, 15% require revision to arthroplasty

Type III: Prosthesis loose or failing

• Treatment: Revision arthroplasty to long-stemmed TKA or distal femoral replacement
• Prognosis: Guarded, high complication rates (30% infection, 20% re-revision)

Lewis-Rorabeck Extension (Modified): Some surgeons add Type IV for interprosthetic fractures (between hip and knee implants), requiring specialized management.

Fracture Patterns and Mechanisms

Supracondylar (Extra-articular):

• Mechanism: Pure bending forces
• Pattern: Transverse or short oblique
• Typical: Elderly osteoporotic bone, low energy fall
• Deformity: Apex anterior (recurvatum) due to gastrocnemius pull

Intercondylar (Complete Articular):

• Mechanism: Axial loading with varus/valgus component
• Pattern: T-shaped or Y-shaped split
• Typical: High-energy trauma, dashboard injury
• Deformity: Condylar widening, rotation, articular step-off

Hoffa (Coronal Plane):

• Mechanism: Shearing force with knee in flexion
• Pattern: Coronal slice of lateral (85%) or medial (15%) condyle
• Typical: Dashboard injury, direct posterior blow
• Deformity: Fragment displaces posteriorly and rotates

Periprosthetic:

• Mechanism: Stress concentration at prosthesis tip, often trivial trauma
• Pattern: Spiral or transverse, typically at component tip
• Typical: Elderly, poor bone quality, anterior notching during TKA
• Deformity: Variable, often minimal displacement initially

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4. Clinical Presentation

History

Mechanism Inquiry: Detailed mechanism is critical for anticipating fracture pattern, soft tissue injury, and associated injuries:

• High-energy: Document speed, height of fall, protective equipment, LOC suggesting polytrauma
• Low-energy: Document simple mechanical fall vs pathological (syncope, seizure)
• Periprosthetic: Document time since TKA, any antecedent pain (suggesting loosening), minimal trauma mechanism

Symptoms:

• Pain: Severe, immediate onset, localized to distal thigh/knee
• Inability to Weight Bear: Universal, patient cannot move leg
• Deformity: Patient or witnesses may report visible angulation
• Swelling: Rapid onset due to fracture hematoma (500-1500ml blood loss)
• Paresthesias: Concerning for nerve injury or compartment syndrome

Past Medical History:

• Previous fractures (osteoporosis screen needed)
• Total knee arthroplasty (date, indication, prior revisions)
• Osteoporosis diagnosis or fragility fractures
• Malignancy (pathological fracture consideration)
• Anticoagulation (bleeding risk, timing of surgery)
• Cardiac/respiratory comorbidities (anesthetic risk)

Examination

Primary Survey (Trauma Protocol): In high-energy mechanisms, follow ATLS protocol:

• Airway, Breathing, Circulation
• Identify life-threatening injuries first
• Secondary survey for associated injuries

Inspection:

• Obvious Deformity: Varus/valgus angulation, shortening, rotation
• Skin Integrity:
  • Open fracture wounds (photograph, document size/contamination)
  • Skin tenting (impending open fracture - urgent reduction needed)
  • Abrasions, bruising pattern (direct blow vs twisting)
  • Posterior thigh inspection (often missed open wounds)
• Swelling: Circumferential thigh swelling, tense compartments
• Limb Alignment: Rotation (compare patellar orientation to contralateral)

Palpation:

• Tenderness: Localized to supracondylar region
• Crepitus: Bone-on-bone grating
• Defects: Palpable fracture gap (suggests significant displacement)
• Compartments: Assess anterior, lateral, posterior compartment tension
• Joint Effusion: Hemarthrosis if intra-articular extension

Neurovascular Examination (MANDATORY - DOCUMENT THOROUGHLY):

Vascular Assessment:

• Popliteal Pulse: Palpate in popliteal fossa (difficult if swollen)
• Dorsalis Pedis Pulse: More reliable, grade 0-2+
• Posterior Tibial Pulse: Behind medial malleolus, grade 0-2+
• Capillary Refill: Normal less than 2 seconds
• Skin Temperature: Cool foot suggests ischemia
• Color: Pale/mottled suggests arterial insufficiency
• Ankle-Brachial Index (ABI): less than 0.9 abnormal, less than 0.5 critical ischemia [5]

Hard Signs of Vascular Injury (IMMEDIATE SURGICAL EXPLORATION):

• Absent distal pulses
• Expanding hematoma
• Pulsatile bleeding
• Bruit or thrill over fracture site
• Pale, pulseless, cold extremity

Soft Signs (CT Angiography Indicated):

• Diminished but palpable pulses
• ABI 0.5-0.9
• Non-expanding hematoma
• History of hemorrhage at scene

Neurological Assessment:

• Common Peroneal Nerve (most vulnerable):

  • "Motor: Ankle dorsiflexion, toe extension"
  • "Sensory: First web space sensation"
  • Foot drop present?

• Tibial Nerve:

  • "Motor: Ankle plantarflexion, toe flexion"
  • "Sensory: Sole of foot"

• Sciatic Nerve: Rare injury, check both divisions

Range of Motion:

• DO NOT assess knee ROM if fracture suspected (causes pain, further displacement)
• Assess hip and ankle motion to rule out associated injuries
• Check for ligamentous laxity if minimal displacement (occult fracture)

Associated Injuries

Ipsilateral Limb (Floating Knee):

• Ipsilateral femoral shaft or neck fracture (5-10%)
• Tibial plateau or shaft fracture (8-15%) - "floating knee" injury
• Patella fracture (3-5%)
• Knee ligament injuries (ACL/PCL/collaterals) - occurs in 20% of high-energy fractures [18]

Polytrauma:

• Chest injuries (rib fractures, pulmonary contusion)
• Abdominal injuries (splenic/hepatic lacerations)
• Pelvic fractures
• Spinal fractures
• Head injury

Compartment Syndrome: Thigh compartment syndrome is rare but devastating due to high compartment volume:

• Anterior Compartment: Quadriceps
• Posterior Compartment: Hamstrings
• Medial Compartment: Adductors

Clinical Signs:

• Pain out of proportion, escalating analgesic requirements
• Pain with passive stretch of compartment muscles
• Tense, swollen compartments
• Paresthesias (late sign)
• Pulselessness (very late, limb-threatening)
• Compartment pressure > 30mmHg or delta pressure less than 30mmHg (difference between diastolic BP and compartment pressure) [19]

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5. Investigations

Imaging Protocol

Initial Radiographs:

Knee AP and Lateral:

• Technique: True AP (patella facing forward) and true lateral (condyles superimposed)
• Coverage: Include 15cm of femoral shaft proximally
• Assessment:
  • Fracture location and pattern
  • Degree of displacement and angulation
  • Articular involvement and step-off
  • Comminution degree
  • Bone quality (osteopenia, cortical thinning)

Femur AP and Lateral:

• Rule out ipsilateral femoral shaft or neck fracture (10% incidence in high-energy trauma)

Traction Radiographs:

• Application of gentle longitudinal traction improves fracture visualization
• Helps differentiate complex fracture lines
• Aids pre-operative planning
• Technique: Assistant applies 10-15kg traction while radiograph obtained

Specific Radiographic Signs:

• Lipohemarthrosis: Fat-fluid level on horizontal beam lateral (indicates intra-articular extension)
• Suprapatellar Effusion: Joint capsule distension
• Hoffa Fragment: Subtle double density on lateral view (posterior condylar fragment)
• Anterior Femoral Notch: Sign of stress riser from previous TKA (periprosthetic risk factor) [16]

Computed Tomography (CT) with 3D Reconstruction:

Indications (MANDATORY for):

• All intra-articular fractures (AO/OTA 33-B and 33-C)
• Suspected Hoffa fracture (coronal plane assessment critical)
• Complex metaphyseal comminution
• Pre-operative planning for all operative cases
• Periprosthetic fractures (assess bone-implant interface)

Protocol:

• Fine-cut axial images (1mm slice thickness)
• Coronal and sagittal reconstructions
• 3D surface rendering for spatial understanding
• Bone window settings

Assessment:

• Articular Surface:

  • Fracture lines through cartilage
  • Step-off measurement (> 2mm requires reduction)
  • Impaction/depression zones
  • Hoffa fragment identification

• Metaphyseal Comminution:

  • Number and size of fragments
  • Bone loss zones
  • Butterfly fragment identification
  • Posterior cortical integrity

• Fracture Line Extension:

  • Proximal extent (important for implant length selection)
  • Intercondylar extension
  • Sagittal vs coronal plane orientation

• Bone Quality:

  • Cortical thickness
  • Trabecular architecture
  • Osteopenia/osteoporosis assessment

CT Angiography:

Indications:

• Abnormal vascular examination (diminished/absent pulses)
• ABI less than 0.9 or side-to-side difference > 0.15
• Hard signs of vascular injury
• High-energy mechanism with posterior displacement > 50%
• Expanding hematoma
• Knee dislocation concurrent with fracture

Protocol:

• Arterial phase imaging from aortic bifurcation to ankles
• 3D reconstructions of popliteal artery course
• Delayed venous phase if venous injury suspected

Assessment:

• Popliteal artery flow and caliber
• Arterial injury: intimal flap, dissection, thrombosis, extravasation, pseudoaneurysm
• Collateral circulation adequacy
• Proximity of artery to fracture fragments

Laboratory Investigations

Pre-operative Workup:

• Complete blood count (Hb for transfusion planning, WCC for infection)
• Coagulation profile (PT/INR, APTT) - especially if anticoagulated
• Group and Save (500-1500ml blood loss expected)
• Renal function (for anesthetic planning)
• Bone profile (calcium, phosphate, ALP, vitamin D) - assess metabolic bone disease
• HbA1c if diabetic (infection risk stratification)

Osteoporosis Screening (for low-energy fractures):

• DEXA Scan: Bone mineral density measurement (order as outpatient/prior to discharge)
• Vitamin D Level: Deficiency (less than 20 ng/mL) in 80% of fragility fractures
• Parathyroid Hormone: If hypercalcemic (exclude hyperparathyroidism)
• Serum/Urine Protein Electrophoresis: If pathological fracture suspected (myeloma)

Compartment Pressure Monitoring: If clinical suspicion of evolving compartment syndrome:

• Handheld Manometer: Serial measurements in anterior, posterior, medial compartments
• Threshold: Absolute pressure > 30mmHg OR delta pressure less than 30mmHg (diastolic BP - compartment pressure)
• Continuous Monitoring: In obtunded/sedated patients unable to report pain [19]

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6. Management Algorithm

                    DISTAL FEMUR FRACTURE SUSPECTED
                                  ↓
                        INITIAL ASSESSMENT
                                  ↓
                    ┌─────────────┴─────────────┐
                    ↓                           ↓
            VASCULAR EXAM                 STABILIZATION
            (Pulses, ABI)              (Splint, Analgesia)
                    ↓                           ↓
        ┌───────────┴───────────┐               ↓
    ABNORMAL               NORMAL          IMAGING
    (Absent/Diminished)    (2+ Pulses)     (XR, CT)
        ↓                       ↓               ↓
    URGENT REDUCTION        FRACTURE      CLASSIFICATION
    ↓                    CLASSIFICATION    (AO/OTA)
    PULSES RETURN?              ↓               ↓
    ┌────┴────┐                 ↓               ↓
   YES       NO          ┌──────┴──────┬────────┴────────┐
    ↓         ↓          ↓             ↓                 ↓
    ↓    CT ANGIO    33-A          33-B              33-C
    ↓    VASCULAR  (Extra-art)  (Partial Art)   (Complete Art)
    ↓    SURGERY       ↓             ↓                 ↓
    ↓         ↓        ↓             ↓                 ↓
    └─────────┴────────┴─────────────┴─────────────────┘
                       ↓
              SOFT TISSUE STATUS?
              ┌────────┴────────┐
          FAVORABLE         UNFAVORABLE
          (Clean, Low      (Open, High
           Energy)          Energy, Swollen)
              ↓                   ↓
              ↓            SPANNING EX-FIX
              ↓            (7-14 days)
              ↓                   ↓
              └───────────────────┘
                       ↓
              PERIPROSTHETIC (TKA)?
              ┌────────┴────────┐
             NO               YES
              ↓                 ↓
              ↓          RORABECK CLASS?
              ↓          ┌──────┼──────┐
              ↓       TYPE I  TYPE II  TYPE III
              ↓         ↓       ↓        ↓
              ↓      BRACE   ORIF    REVISION
              ↓                ↓      ARTHROPLASTY
              └────────────────┘
                       ↓
              DEFINITIVE FIXATION
              ┌────────┴────────┐
          NAIL vs PLATE      ARTICULAR
              ↓              REDUCTION
              ↓                 ↓
      ┌───────┴────────┐        ↓
   EXTRA-ART      INTRA-ART  INTERFRAG
   Simple         Simple      SCREWS
      ↓              ↓           ↓
   RETROGRADE    PLATE +      PLATE
   IM NAIL       LAG SCREWS   FIXATION
      ↓              ↓           ↓
      └──────────────┴───────────┘
                     ↓
              POST-OP PROTOCOL
              (CPM, PT, WB Status)

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7. Management Protocols

Non-Operative Management

Indications (RARE - less than 5% of cases):

• Non-displaced extra-articular fractures in non-ambulatory patients
• Rorabeck Type I periprosthetic fractures (less than 2mm displacement, stable implant)
• Medical comorbidities precluding surgery (terminal illness)
• Patient refusal

Protocol:

• Hinged Knee Brace: Locked in extension initially (2 weeks)
• Progressive Mobilization: Unlock brace for ROM exercises weeks 2-6
• Weight Bearing: Non-weight bearing for 6 weeks, then progressive
• Monitoring: Weekly radiographs x3, then biweekly until healing (12-16 weeks)

Outcomes:

• High rates of malunion (30-40%), particularly varus deformity
• Non-union rate 15-20%
• Knee stiffness nearly universal
• Reserved for very select cases

Operative Management - General Principles

Timing:

• Urgent (less than 6 hours): Open fractures, vascular injury, compartment syndrome
• Early (24-48 hours): Closed fractures with favorable soft tissues
• Delayed (7-14 days): High-energy trauma with soft tissue compromise (after spanning external fixation)

Pre-operative Planning:

• CT scan review in three planes
• Implant selection based on fracture pattern
• Anticipate need for additional implants (Hoffa screws, dual plating)
• Blood availability (group and save minimum)
• Antibiotic prophrophylaxis (cefazolin 2g IV, add gentamicin if open)

Patient Positioning:

• Supine: Standard for lateral plating and retrograde nailing
• Radiolucent Table: Allows intraoperative fluoroscopy AP/lateral
• Contralateral Leg: Flexed/externally rotated or in leg holder for comparison
• Bump Under Hip: Slight internal rotation for true AP imaging

Reduction Principles:

• Length: Restore femoral length (compare to contralateral)
• Alignment: Correct varus/valgus, recurvatum/procurvatum
• Rotation: Match patellar orientation to contralateral side (difficult to assess - use lesser trochanter profile on AP)
• Articular Reduction: Anatomic (step-off less than 2mm) for intra-articular fractures [10]

Reduction Techniques:

• Manual Traction: Assistant provides longitudinal traction
• Femoral Distractor: Apply to lateral femur, allows gradual lengthening
• Joystick Technique: Percutaneous K-wires in fragments for manipulation
• Pointed Reduction Forceps: Clamp articular fragments
• Lag Screw Technique: Intercondylar screws compress articular fragments

Retrograde Intramedullary Nailing

Indications:

• Extra-articular fractures (33-A)
• Simple intra-articular fractures (33-C1)
• Periprosthetic fractures with adequate fixation length distal to prosthesis (> 5cm)
• Ipsilateral femoral shaft fracture
• Bilateral femoral fractures
• Polytrauma (damage control)

Contraindications:

• Complex intra-articular fractures (33-C2/C3) - inadequate distal fixation
• Short distal fragment (less than 4cm) - unstable distal locking
• Narrow intercondylar notch - risk of condylar fracture during insertion
• Severe patellofemoral arthritis - pain with transpatellar approach
• Active knee sepsis

Technique:

1. Incision:

   • Midline longitudinal incision over patellar tendon (4-6cm)
   • Split patellar tendon longitudinally OR medial parapatellar approach (preserve tendon)

2. Entry Point:

   • Anterior edge of intercondylar notch on true lateral fluoroscopy
   • 1cm anterior to PCL insertion (avoid PCL injury)
   • 2-3mm medial to midline on AP (avoids lateral condyle fracture)

3. Guidewire Insertion:

   • Cannulated drill over ball-tip guidewire
   • Confirm central placement in both AP and lateral
   • Advance to proximal femur under fluoroscopy

4. Reaming:

   • Flexible reamers in 0.5mm increments
   • Ream to 1-1.5mm larger than desired nail diameter
   • Typical nail diameter: 10-12mm (females), 11-13mm (males)

5. Nail Insertion:

   • Insert nail over guidewire with gentle mallet blows
   • Ensure nail fully seated (top flush with subchondral bone)
   • Avoid proud nail (causes patellofemoral pain)

6. Distal Locking:

   • Two distal locking screws minimum (bicortical)
   • Use targeting jig for percutaneous insertion
   • Confirm intra-articular placement avoided on lateral view

7. Proximal Locking:

   • Freehand technique using perfect circles
   • One or two screws depending on stability
   • Static locking (no dynamization for distal femur fractures)

Advantages:

• Load-sharing construct (weight transfers through nail)
• Early weight bearing possible
• Minimal soft tissue stripping
• Lower infection risk
• Suitable for bilateral/polytrauma

Disadvantages:

• Requires adequate distal fragment length (> 4cm)
• Risk of iatrogenic condylar fracture during insertion (2-5%)
• Difficult to control rotation and varus/valgus
• Patellofemoral pain (10-15%)
• Cannot address complex articular fractures

Outcomes:

• Union rate: 90-95% at 6 months [6]
• Non-union rate: 5-8%
• Malunion rate: 5-10% (varus most common)
• Knee pain: 10-15% (anterior knee from tendon damage)

Lateral Locked Plating

Indications:

• Complex intra-articular fractures (33-B, 33-C2/3)
• Short distal fragment (less than 4cm)
• Periprosthetic fractures (Rorabeck Type II)
• Coronal plane fractures (Hoffa)
• Failed non-operative management

Plate Options:

• LISS (Less Invasive Stabilization System): Fixed-angle locking, submuscular insertion
• Distal Femoral LCP (Locking Compression Plate): Hybrid locking/compression
• Periarticular Distal Femoral Plate: Pre-contoured, anatomic design
• Periprosthetic Plates: Designed to bypass TKA components

Technique - MIPO (Minimally Invasive Plate Osteosynthesis): [15]

1. Distal Incision (5-8cm):

   • Lateral approach from Gerdy's tubercle extending proximally
   • Develop plane between iliotibial band and vastus lateralis
   • Expose lateral femoral condyle and metaphysis

2. Articular Reduction:

   • Direct visualization of joint surface through distal incision
   • Use pointed reduction forceps to compress intercondylar split
   • Provisional K-wire fixation
   • Confirm anatomic reduction with fluoroscopy (AP/lateral)
   • Interfragmentary lag screws perpendicular to fracture (3.5mm or 4.5mm)

3. Plate Selection:

   • Length: Minimum 8 cortices proximal to fracture (bicortical screw purchase)
   • Distal width: Covers lateral condyle without intra-articular protrusion
   • Check with fluoroscopy before tunneling

4. Submuscular Tunneling:

   • Create submuscular plane beneath vastus lateralis
   • Use blunt instrument (plate itself or periosteal elevator)
   • Slide plate from distal to proximal under muscle
   • Minimize periosteal stripping (preserves blood supply)

5. Proximal Incision (3-5cm):

   • Small incision at proximal plate extent
   • Confirm plate position on femoral shaft
   • Avoid femoral artery medially

6. Distal Fixation:

   • Minimum 4 locking screws in distal fragment (ideally 6-8)
   • Variable angle locking allows multiple trajectories
   • Screws must be bicortical for maximum purchase
   • Avoid intra-articular penetration (check with fluoroscopy)
   • Stagger screw lengths to maximize bone purchase

7. Indirect Reduction:

   • Manipulate plate with bone clamps to achieve alignment
   • Use femoral distractor if needed for length/alignment
   • Joystick K-wires in fragments for positioning
   • Confirm reduction AP/lateral fluoroscopy

8. Proximal Fixation:

   • Minimum 3-4 bicortical screws proximal to fracture
   • Mix of locking and cortical screws (hybrid construct)
   • Working length: 3-5 screw holes empty across fracture (allows micromotion)

Special Consideration - Hoffa Fracture Fixation: If coronal plane Hoffa fragment identified:

• Approach from posterior (knee flexed 90°)
• Reduce fragment and hold with K-wires
• Insert 6.5mm or 7.3mm cannulated screws from posterior-to-anterior
• Screws must be perpendicular to fracture line (not parallel to plate screws)
• Bury screw heads below cartilage surface [11]

Advantages:

• Excellent control of articular reduction
• Fixation of short distal fragments
• Multiple screw trajectories for osteoporotic bone
• Can address Hoffa fragments
• Stable enough for early ROM

Disadvantages:

• Load-bearing construct (delayed weight bearing)
• Higher non-union risk if too rigid (stress shielding) (8-12%) [8]
• Requires intact lateral soft tissue corridor
• Technically demanding
• Soft tissue irritation (prominence)

Outcomes:

• Union rate: 85-92% at 6-9 months
• Non-union rate: 8-12% (higher than nailing)
• Anatomic reduction achieved: 75-85%
• Knee ROM: Average 95-110° flexion
• Hardware irritation: 15-20% require removal

Dual Plating (Medial + Lateral)

Indications:

• Highly comminuted 33-C3 fractures with metaphyseal void
• Bicondylar fractures with severe intercondylar comminution
• Failed single lateral plate (non-union)
• High-demand young patients
• Osteoporotic bone requiring maximal stability

Technique:

• Lateral plate as described above
• Medial plate via separate medial incision
  • Approach between vastus medialis and adductor magnus
  • Avoid saphenous nerve and superficial femoral artery
  • Small 3.5mm locking or one-third tubular plate
• Create symmetric construct biomechanically superior to lateral-only [14]

Advantages:

• 40% increase in construct stiffness
• Reduced varus collapse
• Better control of medial comminution

Disadvantages:

• Extensive soft tissue dissection (devascularization risk)
• Higher infection risk
• Technically demanding
• Prolonged operative time

Distal Femoral Replacement (Arthroplasty)

Indications:

• Rorabeck Type III periprosthetic fractures (loose implant)
• Elderly patients with severe osteoporosis/comminution not amenable to fixation
• Failed ORIF with non-union in elderly
• Pathological fractures (metastatic disease, myeloma)
• Salvage procedure

Technique:

• Remove existing TKA components and fractured bone
• Insert long-stemmed hinged total knee or distal femoral replacement (megaprosthesis)
• Bypass fracture zone by 2 cortical diameters (~15cm)
• Cemented stems in osteoporotic bone

Advantages:

• Immediate stability (weight bearing as tolerated day 1)
• No healing required
• Rapid return to function in elderly
• Single operation ("one and done")

Disadvantages:

• High infection risk (10-15%)
• Aseptic loosening (15-20% at 5 years)
• Periprosthetic fracture around revision components (8-10%)
• Reserved for salvage/elderly only

Outcomes:

• Mortality: 10% at 1 year (elderly, comorbid population)
• Revision rate: 20-25% at 5 years
• Functional outcomes: Satisfactory in 70%

Post-operative Protocols

Immobilization:

• Hinged knee brace (unlocked for ROM) for 6 weeks
• Remove for physiotherapy and sleeping after 2 weeks if stable fixation

Weight Bearing:

• Retrograde Nail: Touch weight bearing (10-20kg) progressing to weight bearing as tolerated by 6 weeks
• Lateral Plate: Non-weight bearing 6 weeks, then progressive loading
• Dual Plate: Non-weight bearing 8-12 weeks (more rigid, slower biological healing)
• Distal Femoral Replacement: Weight bearing as tolerated immediately

Range of Motion:

• Start immediately (day 1-2 post-op) to prevent arthrofibrosis
• CPM (Continuous Passive Motion): 0-90° for 6-8 hours/day for 4 weeks
• Active ROM: Quadriceps isometrics, straight leg raises
• Goal: 90° flexion by 6 weeks, 110° by 12 weeks
• If less than 90° flexion at 12 weeks: Consider MUA (manipulation under anesthesia)

Physiotherapy:

• Quadriceps strengthening (prevent atrophy)
• Patellofemoral mobilization (prevent stiffness)
• Gait training with assistive devices
• Proprioception and balance training

Radiographic Monitoring:

• Post-op: Day 1 (confirm reduction/hardware)
• Weeks 2, 6, 12, 24
• Assess: Alignment, hardware position, fracture healing (callus formation)
• Union criteria: Bridging callus on 3/4 cortices, pain-free weight bearing

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8. Complications

Early Complications

Vascular Injury (2-3%): [5]

• Mechanism: Popliteal artery tethered at adductor hiatus, injured by sharp bone fragment or stretch
• Presentation: Absent pulses, pale cold foot, expanding hematoma
• Management:
  • Immediate fracture reduction
  • If pulses do not return → urgent vascular surgery consultation
  • CT angiography if time permits
  • "Surgical options: primary repair, interposition vein graft, synthetic graft"
• Amputation risk: 10-15% if > 6 hours to revascularization

Nerve Injury (1-3%):

• Common Peroneal Nerve (most common): Foot drop, sensory loss first web space
  • Usually neuropraxia from traction
  • "Recovery: 60-80% spontaneous within 3-6 months"
  • Ankle-foot orthosis for support
  • EMG/NCS at 6 weeks if no recovery
• Tibial Nerve (rare): Plantarflexion weakness, plantar numbness
• Sciatic Nerve (very rare): Combined deficit

Compartment Syndrome (less than 1%): [19] Rare in isolated distal femur fractures but devastating if missed

• Diagnosis: Pain out of proportion, pain on passive stretch, tense compartments, pressure > 30mmHg
• Management: Urgent fasciotomy (anterolateral and medial incisions for all 3 thigh compartments)
• Delay > 8 hours: Permanent muscle necrosis, contracture, amputation risk

Fat Embolism Syndrome (1-2%): More common with intramedullary nailing

• Classic Triad: Hypoxia, confusion, petechial rash (upper body)
• Timing: 24-72 hours post-injury
• Management: Supportive (oxygen, fluid resuscitation), rarely requires intubation

Infection:

• Closed Fractures: 1-3% with modern techniques
• Open Fractures: 10-30% depending on Gustilo grade
• Risk Factors: Open fracture, diabetes, smoking, delayed fixation
• Prevention:
  • Timely antibiotic prophylaxis (cefazolin 2g pre-incision)
  • Meticulous soft tissue handling
  • MIPO technique (minimizes stripping)
• Treatment:
  • "Superficial: PO antibiotics, local wound care"
  • "Deep: Irrigation and debridement, retain hardware if stable, 6 weeks IV antibiotics"

Bleeding/Hematoma:

• Expected blood loss: 500-1500mL
• Transfusion threshold: Hb less than 70 g/L (restrictive strategy)
• Hematoma: Managed conservatively unless expanding or compromising wound

Late Complications

Non-Union (5-10%): [8] Failure of fracture healing at 6-9 months

Risk Factors:

• Lateral plate fixation (load-bearing, stress shielding)
• Excessive rigidity (dual plating with short working length)
• Severe comminution with bone loss
• Infection
• Smoking
• NSAIDs
• Osteoporosis

Classification:

• Hypertrophic: Abundant callus, inadequate stability → revision fixation
• Atrophic: No callus, avascular → bone grafting + revision fixation

Treatment:

• Hypertrophic: Revision to nail (dynamization) or bone grafting + plate augmentation
• Atrophic: Revision fixation + autologous bone graft (iliac crest) or BMP-2
• Salvage: Distal femoral replacement in elderly

Malunion (10-20%): Healed in non-anatomic position

Common Patterns:

• Varus (most common): Adductor magnus pull, medial comminution
• Recurvatum: Gastrocnemius pull
• Rotation: Difficult to assess intraoperatively
• Leg Length Discrepancy: Shortening > 2cm symptomatic

Consequences:

• Altered knee biomechanics (accelerated arthritis)
• Gait abnormality
• Patellofemoral maltracking
• Pain

Treatment:

• If symptomatic and less than 1 year old: Corrective osteotomy + revision fixation
• If > 1 year or elderly: Observe if well-tolerated, or total knee arthroplasty for arthritis

Knee Stiffness/Arthrofibrosis (30-50%): Most common long-term complication

Risk Factors:

• Prolonged immobilization
• Intra-articular fracture
• Quadriceps scarring to fracture site
• Inadequate post-op physiotherapy
• Patient non-compliance

Presentation:

• Inability to achieve > 90° flexion by 12 weeks
• Quadriceps lag (extensor mechanism dysfunction)
• Patella baja (inferior position from scarring)

Prevention:

• Immediate ROM exercises (day 1-2 post-op)
• CPM machine
• Aggressive physiotherapy

Treatment:

• Continued physiotherapy if mild (less than 90° but improving)
• MUA (Manipulation Under Anesthesia) at 3-4 months if plateau less than 90°
• Arthroscopic arthrolysis at 6-12 months (release adhesions, debride scarring)
• Open quadricepsplasty (rare, extensive scarring)

Post-Traumatic Arthritis (20-40% of intra-articular fractures): [9] Degenerative changes from articular cartilage damage

Risk Factors:

• Articular step-off > 2mm [10]
• Severe cartilage impaction
• Missed Hoffa fragment
• Malunion
• Age > 50 years

Presentation:

• Knee pain with activity
• Stiffness
• Swelling/effusions
• Reduced walking distance

Management:

• Non-operative: NSAIDs, physiotherapy, weight loss, activity modification, bracing
• Injections: Corticosteroid (temporary relief), hyaluronic acid (weak evidence)
• Operative: Total knee arthroplasty when conservative measures fail
  • Challenging due to bone loss, deformity, hardware
  • Requires hardware removal, often bone grafting
  • Higher complication rate than primary TKA

Hardware Complications (10-20%):

• Symptomatic Hardware: Lateral plate prominence causing iliotibial band irritation
  • "Treatment: Elective removal after union (12-18 months)"
• Screw Loosening: In osteoporotic bone, particularly around TKA
• Plate Breakage: Usually indicates non-union
• Intra-articular Screw Penetration: Causes pain, arthritis
  • "Treatment: Screw removal ± chondroplasty if cartilage damage"

Heterotopic Ossification (5-10%): Bone formation in soft tissues around knee

• Risk Factors: High-energy trauma, head injury, delayed fixation
• Prevention: Indomethacin 25mg TDS for 6 weeks (limited evidence)
• Treatment: Excision if limits ROM, but only after maturation (12-18 months)

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9. Prognosis and Outcomes

Union Rates

Overall Union:

• Extra-articular fractures: 90-95% union by 6 months
• Intra-articular fractures: 85-90% union by 9 months
• Periprosthetic fractures: 75-85% union (dependent on bone quality and implant stability)

Factors Influencing Healing:

• Fracture pattern (simple vs comminuted)
• Soft tissue injury severity
• Fixation adequacy
• Patient age and comorbidities
• Smoking status (doubles non-union risk)
• Metabolic bone disease

Functional Outcomes

Knee Range of Motion:

• Expected ROM: 0-110° flexion (normal 0-135°)
• Good outcome: > 90° flexion (adequate for activities of daily living)
• Poor outcome: less than 90° flexion (difficulty with stairs, sitting, rising from chair)
• Extension lag: Common in first 3 months, usually resolves with physiotherapy

Return to Activities:

• ADLs: 3-6 months in uncomplicated cases
• Driving: 3-4 months (when off opioids, can perform emergency stop)
• Work:
  • "Sedentary: 3-4 months"
  • "Manual labor: 6-12 months"
• Sports:
  • "Low-impact: 6-9 months"
  • "High-impact: 9-12 months, may never return to pre-injury level"

Patient-Reported Outcomes:

• SF-36 Physical Component: 60-70% of pre-injury score at 1 year
• KOOS (Knee Injury and Osteoarthritis Outcome Score): 65-75 at 1 year
• Return to pre-injury activity level: 40-60%

Prognostic Factors

Good Prognosis:

• Young patient (less than 50 years)
• Extra-articular fracture
• Low-energy mechanism
• Anatomic reduction achieved
• Stable fixation
• Early mobilization
• Non-smoker
• Good bone quality

Poor Prognosis:

• Elderly (> 70 years)
• High-energy trauma
• Complex intra-articular fracture (33-C3)
• Significant comminution
• Open fracture
• Vascular injury
• Periprosthetic fracture with loose implant
• Osteoporosis
• Smoking
• Diabetes

---

10. Special Populations

Elderly Patients

Considerations:

• Predominantly low-energy falls on osteoporotic bone
• Higher periprosthetic fracture rate (TKA prevalence)
• Medical comorbidities (cardiac, respiratory, renal)
• Polypharmacy (anticoagulation common)
• Increased surgical risk

Management Modifications:

• Consider distal femoral replacement over fixation if severe osteoporosis/comminution
• Accept some deformity in non-ambulatory patients
• Optimize medical status pre-operatively
• Multidisciplinary care (geriatrician, physiotherapy, occupational therapy)
• Early mobilization critical (prevent deconditioning)

Outcomes:

• Higher mortality: 10% at 1 year (cf. 1% in young)
• Higher complication rates: infection, non-union
• Functional recovery slower
• Many do not return to independent ambulation

Polytrauma Patients

Considerations:

• Life-threatening injuries take priority (ATLS protocol)
• Damage control orthopaedics approach
• Fat embolism risk with early definitive fixation

Management:

• Initial: Spanning external fixator (femur-to-tibia)
• Definitive fixation when medically stable and soft tissues permit (7-14 days)
• Retrograde nail preferred (faster, less physiologic insult than plating)

Open Fractures

Classification (Gustilo-Anderson):

• Grade I: less than 1cm wound, low energy, minimal contamination
• Grade II: 1-10cm wound, moderate soft tissue damage
• Grade III: > 10cm wound, extensive soft tissue damage
  • "IIIA: Adequate soft tissue coverage"
  • "IIIB: Requires flap coverage"
  • "IIIC: Vascular injury requiring repair"

Management:

1. Emergency Department:

   • Remove gross contamination
   • Saline-soaked sterile dressing
   • IV antibiotics (cefazolin + gentamicin, add penicillin if farm injury)
   • Tetanus prophylaxis
   • Splint and analgesia

2. Operating Room (less than 6 hours):

   • Irrigation and debridement (pulse lavage, 6-9L saline)
   • Remove all foreign material and devitalized tissue
   • Stabilization: Spanning external fixator preferred initially
   • Leave wound open (delayed primary closure or VAC dressing)

3. Definitive Fixation:

   • Delay 7-14 days until soft tissues healed
   • Conversion to internal fixation (plate or nail)

Outcomes:

• Infection risk: Grade I (2%), Grade II (5-10%), Grade III (10-50%)
• Non-union risk: Grade I (5%), Grade II (10%), Grade III (15-25%)

---

11. Evidence & Guidelines

Key Studies

Retrograde Nail vs Lateral Plate: Multiple studies demonstrate comparable union rates (90-95%) but differing complication profiles. Nailing allows earlier weight bearing and has lower infection risk, but limited to extra-articular/simple intra-articular fractures. Plating allows better articular reduction but higher non-union risk (8-12% vs 5-8%). [6,7]

Dual Plating: Biomechanical studies show 40% increase in construct stiffness with dual plating compared to lateral-only, reducing varus collapse. Clinical outcomes demonstrate lower malunion rates but no difference in union rates. Reserved for highly comminuted 33-C3 fractures in high-demand patients. [14]

MIPO vs Open Plating: MIPO (Minimally Invasive Plate Osteosynthesis) preserves periosteal blood supply and reduces soft tissue complications. Meta-analyses show lower infection rates (2% vs 8%), similar union rates, but potentially higher malunion rates due to indirect reduction challenges. [15]

Periprosthetic Fracture Management: Rorabeck Type II fractures (displaced, stable implant) treated with ORIF have 75% union rate but 15-20% require conversion to arthroplasty. Type III (loose implant) should undergo primary revision arthroplasty with long-stemmed components rather than attempting fixation with poor bone-implant interface. [4]

Distal Femoral Replacement: In elderly patients with severe osteoporosis, distal femoral replacement (megaprosthesis) allows immediate weight bearing and avoids non-union risk. However, 5-year survival is only 75-80% due to infection and aseptic loosening. Reserved for salvage or patients unable to comply with weight bearing restrictions. [12]

Guidelines

AO Principles:

• Anatomic reduction of articular surface (step-off less than 2mm)
• Stable fixation allowing early mobilization
• Preservation of blood supply (MIPO technique)
• Early active mobilization

OTA Recommendations:

• CT scan mandatory for all intra-articular fractures
• Damage control principles in polytrauma/high-energy trauma
• Lateral locked plating for complex articular fractures
• Retrograde nailing for extra-articular and simple intra-articular patterns

---

12. Patient Education

Understanding the Injury

You have broken the thigh bone (femur) right where it meets the knee joint. Imagine a pillar supporting a building - you've broken the bottom of that pillar where it's widest. Sometimes the smooth joint surface inside the knee is also cracked, which is more serious because it can lead to arthritis later.

This injury happened because [high-energy trauma: the force from your accident was very strong / low-energy fall: your bones are weaker due to age/osteoporosis, so even a simple fall caused a break].

Why Surgery is Needed

Unlike a simple wrist fracture, this cannot heal in a cast because:

• The powerful thigh muscles pull the bone pieces out of position
• The knee joint surface must be perfectly smooth (any step creates arthritis)
• Your leg would be stuck straight in a cast for 3 months (causing permanent stiffness)

We will perform surgery to:

1. Piece together the joint surface like a jigsaw puzzle
2. Hold everything with a metal plate and screws (or a rod inside the bone)
3. Allow you to start bending your knee within days to prevent stiffness

The Recovery Journey

Hospital (3-7 days):

• Pain control with medications
• Start bending knee with physiotherapist day 1-2 (yes, really!)
• Learn to use crutches/walker
• X-rays to check position

First 6 Weeks:

• Weight Bearing: Touch your toe to ground only (like testing bath water temperature)
• Knee Bending: Use machine (CPM) and physiotherapy to reach 90° (right angle)
• Wound Care: Keep clean and dry, stitches out at 2 weeks
• Medications: Pain relief, blood thinner injections (prevent clots)

6 Weeks to 3 Months:

• X-ray shows bone healing → increase weight bearing progressively
• Goal: Walk without crutches by 3 months
• Knee bending goal: 110° (enough for stairs, car, toilet)

3 to 12 Months:

• Bone fully healed on X-ray (bridging callus visible)
• Return to normal activities gradually
• Driving when off strong painkillers (usually 3-4 months)
• Work: Desk job 3-4 months, manual labor 6-12 months

What Can Go Wrong?

Common (happens to 1 in 5 people):

• Stiff Knee: Most common problem. Your knee may not bend as far as before (normal 135°, expect 110°). Prevention: Do your physiotherapy exercises religiously.
• Pain: Some people have ongoing knee pain, especially in cold weather or after activity.

Uncommon (happens to 1 in 20 people):

• Non-Union (Bone Doesn't Heal): May need further surgery (bone grafting or changing the metalwork).
• Infection: Redness, warmth, discharge from wound. Needs antibiotics, sometimes more surgery.

Rare but Serious (happens to 1 in 100 people):

• Artery Injury: We check your foot pulses during surgery. Very rare but can threaten the leg.
• Nerve Injury: Foot drop (can't lift foot up) if the peroneal nerve is injured. Usually recovers.

Long-Term (may develop over years):

• Arthritis: If the joint surface was damaged, you may develop arthritis in 5-10 years. May need knee replacement eventually.

When to Seek Help

Call immediately or go to Emergency if:

• Foot becomes cold, pale, or numb
• Severe pain not controlled by medications
• Wound becomes very red, hot, or discharges pus
• Calf becomes swollen, painful (blood clot concern)
• Fever > 38.5°C

Call clinic during hours if:

• Unable to achieve physiotherapy goals
• Wound not healing well
• Ongoing concerns about progress

Long-Term Outlook

Most People:

• Walk independently by 3-6 months
• Return to most daily activities by 6-12 months
• Some limitation in knee bending (expect 110° vs normal 135°)
• May have some pain with weather changes or prolonged activity

Best Outcomes:

• Young patients with simple fractures
• Non-smokers
• Those who do physiotherapy diligently
• Good bone quality

Challenges:

• Elderly patients may not return to previous independence
• High-energy injuries with severe damage take 12-18 months full recovery
• Some never return to high-impact sports

Questions to Ask Your Surgeon

1. What type of fracture do I have? (Show me on the X-ray/CT)
2. What surgery are you planning? (Plate, rod, or knee replacement?)
3. When can I start walking?
4. How much knee bending should I expect?
5. When can I drive/return to work?
6. Will I need the metal removed later?
7. What are MY specific risks given my age/health/fracture?

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13. References

1. Martinet O, Cordey J, Harder Y, et al. The epidemiology of fractures of the distal femur. Injury. 2000;31 Suppl 3:C62-63. PMID: 11052383.

2. Court-Brown CM, Caesar B. Epidemiology of adult fractures: A review. Injury. 2006;37(8):691-697. doi:10.1016/j.injury.2006.04.130

3. Elsoe R, Ceccotti AA, Larsen P. Population-based epidemiology and incidence of distal femur fractures. Int Orthop. 2018;42(1):191-196. doi:10.1007/s00264-017-3665-1

4. Rorabeck CH, Taylor JW. Classification of periprosthetic fractures complicating total knee arthroplasty. Orthop Clin North Am. 1999;30(2):209-214. doi:10.1016/s0030-5898(05)70075-4

5. Scharfenberg JE, Hallock GG. Popliteal artery injury in closed fracture of the distal femur. J Trauma. 1982;22(7):621-625. doi:10.1097/00005373-198207000-00014

6. Griffin XL, Parsons N, Zbaeda MM, McArthur J. Interventions for treating fractures of the distal femur in adults. Cochrane Database Syst Rev. 2015;(8):CD010606. doi:10.1002/14651858.CD010606.pub2

7. Henderson CE, Kuhl LL, Fitzpatrick DC, Marsh JL. Locking plates for distal femur fractures: is there a problem with fracture healing? J Orthop Trauma. 2011;25 Suppl 1:S8-14. doi:10.1097/BOT.0b013e3182070127

8. Ricci WM, Streubel PN, Morshed S, et al. Risk factors for failure of locked plate fixation of distal femur fractures: an analysis of 335 cases. J Orthop Trauma. 2014;28(2):83-89. doi:10.1097/BOT.0b013e31829e6dd0

9. Nauth A, Schemitsch E, Norris B, Nollin Z, Watson JT. Critical-size bone defects: is there a consensus for diagnosis and treatment? J Orthop Trauma. 2018;32 Suppl 1:S7-S11. doi:10.1097/BOT.0000000000001115

10. Marsh JL, Buckwalter J, Gelberman R, et al. Articular fractures: does an anatomic reduction really change the result? J Bone Joint Surg Am. 2002;84(7):1259-1271. doi:10.2106/00004623-200207000-00026

11. Letenneur J, Labour PE, Rogez JM, et al. Hoffa's fractures. Report of 20 cases. Ann Chir. 1978;32(3-4):213-219. PMID: 686330.

12. Hoellwarth JS, Fourman MS, Crossett L, et al. Equivalent mortality and complication rates following periprosthetic distal femur fractures managed with either lateral locked plating or a distal femoral replacement. Injury. 2018;49(2):392-397. doi:10.1016/j.injury.2017.11.040

13. Scalea TM, Boswell SA, Scott JD, Mitchell KA, Kramer ME, Pollak AN. External fixation as a bridge to intramedullary nailing for patients with multiple injuries and with femur fractures: damage control orthopedics. J Trauma. 2000;48(4):613-621. doi:10.1097/00005373-200004000-00006

14. Kiyono M, Noda T, Nagano H, et al. Biomechanical effects of medial plate augmentation for the locking plate fixation of distal femoral fractures. J Orthop Sci. 2021;26(3):442-448. doi:10.1016/j.jos.2020.04.002

15. Kregor PJ, Stannard JA, Zlowodzki M, Cole PA. Treatment of distal femur fractures using the less invasive stabilization system: surgical experience and early clinical results in 103 fractures. J Orthop Trauma. 2004;18(8):509-520. doi:10.1097/00005131-200409000-00006

16. Ritter MA, Thong AE, Keating EM, et al. The effect of femoral notching during total knee arthroplasty on the prevalence of postoperative femoral fractures and on clinical outcome. J Bone Joint Surg Am. 2005;87(11):2411-2414. doi:10.2106/JBJS.D.02468

17. Trueta J, Cavadias AX. Vascular changes caused by the Küntscher type of nailing: an experimental study in the rabbit. J Bone Joint Surg Br. 1955;37-B(3):492-505. doi:10.1302/0301-620X.37B3.492

18. Halvorson JJ, Anz A, Langfitt M, et al. Vascular injury associated with extremity trauma: initial diagnosis and management. J Am Acad Orthop Surg. 2011;19(8):495-504. doi:10.5435/00124635-201108000-00005

19. McQueen MM, Gaston P, Court-Brown CM. Acute compartment syndrome. Who is at risk? J Bone Joint Surg Br. 2000;82(2):200-203. doi:10.1302/0301-620x.82b2.9799

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14. Examination Focus (Viva Vault)

Question 1: Classify this distal femoral fracture and outline your management

Examiner Shows CT Scan: Intercondylar fracture with metaphyseal comminution

Structured Answer:

"This is a distal femoral fracture. Let me classify it systematically using the AO/OTA system:

Classification: This appears to be an AO/OTA 33-C2 fracture:

• 33 = Distal Femur
• C = Complete articular (both condyles separated from shaft and each other)
• 2 = Simple articular split with complex metaphyseal comminution

On the coronal CT slices, I would carefully look for a Hoffa fragment - a coronal plane fracture easily missed on standard views.

Management Approach:

1. Initial Assessment:

   • Primary survey if high-energy mechanism
   • Neurovascular examination documenting pulses bilaterally and ABI
   • Assess soft tissue envelope

2. Imaging:

   • This CT scan is essential - I would review in three planes
   • Look specifically for: articular step-off, degree of comminution, Hoffa fragment, bone quality

3. Surgical Planning:

   • This requires open reduction and internal fixation with lateral locked plate
   • Retrograde nail insufficient for this complex articular fracture

4. Surgical Technique - MIPO Approach:

   • Distal lateral incision to expose articular surface
   • Reduce intercondylar split with pointed forceps, provisionally fix with K-wires
   • Lag screws perpendicular to fracture line (3.5mm or 4.5mm)
   • Confirm anatomic reduction (less than 2mm step-off) on fluoroscopy
   • Submuscular plate tunneling to preserve periosteal blood supply
   • Minimum 4 locking screws distally, 3-4 screws proximally
   • Consider dual plating if severe medial comminution in young patient

5. Post-operative Protocol:

   • Hinged brace unlocked for ROM immediately (day 1)
   • CPM machine 0-90° for 6-8 hours daily
   • Non-weight bearing 6 weeks
   • Serial radiographs at 2, 6, 12 weeks

Complications to Counsel:

• Stiffness (30-50%) - most common
• Non-union (8-12% with lateral plate)
• Post-traumatic arthritis (20-40% of intra-articular fractures)
• Infection (1-3%) "

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Question 2: What is a Hoffa fracture and why is it clinically significant?

Structured Answer:

"A Hoffa fracture is a coronal plane fracture of the femoral condyle, first described by Albert Hoffa in 1904. It represents a partial articular fracture (AO/OTA 33-B3).

Anatomical Pattern:

• Fracture line oriented in the coronal/frontal plane - like slicing a loaf of bread
• Lateral condyle involved in 85% of cases (medial 15%, rarely both)
• Fragment typically includes posterior portion of weight-bearing articular surface

Mechanism:

• Shearing force applied to flexed knee
• Dashboard injury is classic
• Direct posterior blow driving condyle anteriorly

Clinical Significance - Four Key Points:

1. Easily Missed Radiographically:

   • Often invisible on AP radiograph because intact anterior cortex obscures the fragment
   • Subtle on lateral (double density sign)
   • CT scan mandatory - shows fragment clearly on coronal reconstructions
   • Missing this leads to failed reduction and persistent instability

2. Inherently Unstable:

   • Fragment displaced posteriorly by gastrocnemius muscle pull
   • Unstable in both flexion and extension
   • Cannot be treated conservatively

3. Requires Specific Fixation Technique:

   • Standard lateral plate screws run parallel to fracture line - insufficient
   • Needs screws perpendicular to fracture plane:
     • Posterior-to-anterior OR anterior-to-posterior approach
     • 6.5mm or 7.3mm cannulated screws
     • Multiple screws (usually 2-3) for rotational stability
   • Must bury screw heads below articular cartilage if anterior approach

4. Poor Outcomes if Missed:

   • Persistent articular incongruity
   • Post-traumatic arthritis develops rapidly
   • Fixation failure of main fracture due to unrecognized instability

Search Protocol: On every distal femur fracture CT scan, I systematically scroll through coronal reconstructions looking for a coronal split, particularly in the lateral condyle."

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Question 3: Describe the deforming forces in a distal femoral fracture

Structured Answer:

"The distal femur fracture has characteristic deforming forces from muscular attachments:

1. Gastrocnemius - Distal Fragment Extension (Recurvatum):

• Anatomy: Medial and lateral heads originate from posterior femoral condyles
• Force: Pulls distal fragment into extension/recurvatum (apex anterior angulation)
• Clinical Significance: Creates a sharp posterior spike of proximal fragment that can impale the popliteal neurovascular bundle
• Reduction Strategy: Flex the knee to relax gastrocnemius during reduction

2. Adductor Magnus - Proximal Fragment Varus:

• Anatomy: Inserts on adductor tubercle (medial supracondylar ridge)
• Force: Pulls proximal shaft into varus (apex lateral) and adduction
• Clinical Significance: Classic varus deformity seen on AP radiograph
• Reduction Strategy: Manual valgus force and abduction during fixation

3. Quadriceps - Shortening:

• Anatomy: Four heads insert via patellar tendon, but vastus muscles adhere along shaft
• Force: Proximal pull creating shortening and superior displacement
• Reduction Strategy: Longitudinal traction, femoral distractor if needed

4. Hamstrings - Shortening and Flexion:

• Anatomy: Biceps femoris, semitendinosus, semimembranosus from posterior thigh
• Force: Contribute to shortening and slight flexion of proximal fragment
• Reduction Strategy: Traction, knee positioning

Combined Deformity Pattern: A typical displaced distal femur fracture shows:

• AP View: Varus angulation (adductor pull), shortening
• Lateral View: Apex anterior angulation/recurvatum (gastrocnemius pull)
• Clinical: Palpable gap, rotational deformity

Reduction Principle: Must counter these forces during surgery:

• Longitudinal traction (reverse shortening)
• Valgus force (counter varus)
• Knee flexion (relax gastrocnemius)
• Assess rotation compared to contralateral (patellar orientation, lesser trochanter profile)"

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Question 4: Classify periprosthetic distal femoral fractures and outline management

Structured Answer:

"Periprosthetic distal femoral fractures occur around total knee arthroplasty components, with incidence 0.6-2.5% after primary TKA. The Rorabeck-Lewis Classification stratifies based on two factors: displacement and implant stability.

Classification:

Type I: Non-displaced, Prosthesis Stable

• Minimal displacement (less than 5mm)
• Femoral component well-fixed to bone
• Represents ~20% of cases

Type II: Displaced, Prosthesis Stable (MOST COMMON - 65%)

• Significant displacement (> 5mm)
• Femoral component remains well-fixed
• Fracture typically at tip of component (stress concentration)

Type III: Prosthesis Loose or Failing

• Implant loosening evident (pre-existing or fracture-induced)
• Loss of bone-implant interface
• Represents ~15% of cases

Management by Type:

Type I - Non-operative:

• Hinged knee brace locked in extension
• Protected weight bearing (touch toe only)
• Serial radiographs (weekly x3, then biweekly)
• Union rate: 85%
• Risk: Displacement → convert to Type II management

Type II - ORIF (Open Reduction Internal Fixation):

• Lateral Locked Plate:
  • Long plate bypassing prosthesis tip by 2 cortical diameters (~10cm)
  • Multiple locking screws distally around component
  • Bicortical purchase where possible
  • Avoid cement mantle with screws
• Alternative - Retrograde Nail (if adequate distal bone > 5cm):
  • Insert via previous TKA box
  • Requires open intercondylar notch to accommodate nail
  • Not suitable if TKA has closed box design
• Post-op: Non-weight bearing 6-8 weeks, progressive loading
• Outcomes: 75% union rate, 15-20% require conversion to arthroplasty

Type III - Revision Arthroplasty:

• Indication: Attempting fixation on loose implant doomed to fail
• Technique:
  • Remove loose TKA components
  • Long-stemmed revision TKA OR distal femoral replacement (megaprosthesis)
  • Bypass fracture by 2 cortical diameters
  • Cemented stems in osteoporotic bone
• Advantages: Immediate weight bearing, single surgery
• Disadvantages: High infection risk (10-15%), aseptic loosening (15-20% at 5 years)
• Outcomes: 70% satisfactory function, 20-25% revision rate at 5 years

Key Decision Factors:

• Patient Age: Young → favor fixation, Elderly → consider arthroplasty even Type II
• Bone Quality: Severe osteoporosis → arthroplasty may be safer
• Fracture Pattern: Severe comminution → arthroplasty
• Patient Activity: Non-ambulatory → may consider non-operative even Type II"

(End of Enhanced Topic)