Summary

Distal femoral fractures involve the supracondylar or intercondylar region of the femur. They are challenging injuries due to the proximity to the knee joint, often resulting in stiffness and cartilage damage. There is a bimodal distribution: High energy trauma in young patients, and low energy falls in elderly (often with a Total Knee Replacement = Periprosthetic). The Popliteal Artery is tethered posteriorly and at high risk in displaced extension-type fractures. Management typically involves Lateral Locking Plates or Retrograde Nails. [1,2,3]

Key Facts

• The Deforming Forces: The Gastrocnemius muscle originates on the femoral condyles. In a supracondylar fracture, it pulls the distal fragment into recurvatum (Extension). This drives the sharp posterior edge of the bone directly into the neurovascular bundle.
• Hoffa Fracture: A specific type of intra-articular fracture occurring in the Coronal Plane (like a loaf of bread). It is easily missed on standard X-rays but visible on CT. If missed, the reduction fails.
• Periprosthetic Fractures: Occur around the stem of a knee replacement. These are epidemic in the elderly. Classification (Rorabeck/Lewis) depends on whether the implant is loose.

Clinical Pearls

"Check the Pulse and Feet": The Popliteal artery is tethered at the adductor hiatus proximal to the fracture. Displacement stretches it. Always check ABI if in doubt.

"Spanning ExFix": In high energy trauma (or if soft tissues are swollen), do NOT plate immediately. The risk of infection is immense. Use a spanning external fixator (Femur to Tibia) for 7-14 days to let the "soft tissues settle". This is Damage Control Orthopaedics.

"The Hoffa Fragment": Almost always involves the Lateral Condyle (85%). It needs separate screw fixation from back-to-front or front-to-back.

              DISTAL FEMUR FRACTURE
                       ↓
              NEUROVASCULAR STATUS?
              ┌───────┴───────┐
       PULSELESS             INTACT
           ↓                    ↓
      URGENT REDUCTION       JOINT INVOLVED?
      (On Table)             ┌────┴────┐
           ↓                NO        YES
        VASCULAR            (33-A)    (33-C)
        SURGERY              ↓         ↓
                         IS IT A TKR?  CT SCAN
                         ┌───┴───┐     (Plan)
                        NO       YES      ↓
                        ↓         ↓     STABLE
                    NAIL/PLATE  NAIL    SOFT TISSUE?
                               OR PLATE ┌───┴───┐
                                       YES      NO
                                        ↓       ↓
                                      ORIF     EX-FIX
                                     (Plate) (Damage Control)

1. Retrograde Intramedullary Nail

• Indication: Extra-articular (33-A) or Simple Intra-articular (33-C1). Periprosthetic fractures.
• Technique: Through the patellar tendon, up the intercondylar notch.
• Pros: Load sharing (allows early weight bearing). Minimal soft tissue stripping.
• Cons: Can damage knee cartilage. Hard to control distal blocks.

2. Lateral Locking Plate (LISS / VA-LCP)

• Indication: Complex intra-articular fractures (33-C2/C3).
• Technique: "Less Invasive Stabilization System" (LISS). Submuscular insertion. The screws "Lock" into the plate, creating a fixed-angle device that acts as an "Internal External Fixator".
• Pros: Catching multiple small fragments. Anatomic reduction of joint surface possible.
• Cons: Non-union rate higher (too stiff). Load bearing (cannot walk for 6 weeks).

3. Revision Arthroplasty (Distal Femoral Replacement)

• Indication: Elderly with comminuted periprosthetic fracture (Rorabeck III) or severe arthritis.
• Technique: Remove the broken bone and knee replacement. Insert a massive "Tumour" prosthesis (Mega-prosthesis).
• Pros: Immediate mobilization ("One and Done"). No healing required.
• Cons: High infection rate. High failure rate long term. "Salvage only".

Fixation vs Replacement

• In the elderly, Distal Femoral Replacement (DFR) is showing superior early outcomes compared to fixation (which has 20-30% failure rate in osteoporotic bone).

Dual Plating

• Latest evidence suggests "Lateral Locking Plate" alone is too stiff yet asymmetrical, causing non-union.
• Adding a medial plate (Dual Plating) increases stability but requires extensive dissection.

The Injury

You have broken the thigh bone right where it meets the knee. It is like shattering the bottom of a pillar. The knee joint surface is often split.

The Plan

• Goal: To reconstruct the smooth joint surface perfectly to prevent arthritis.
• Surgery: We usually slide a plate under the muscle and put many screws in to hold the pieces like a jigsaw.
• The Knee: Will be stiff. You must bend it as soon as the pain allows.

Recovery

• Weight Bearing: Usually "Touch Weight Bearing" (Tip toe) for 6 weeks until bone heals.
• Bending: Use a machine (CPM) to bend the knee for you.
• Long term: Risk of arthritis is real.

Q1: What is a Hoffa Fracture and why is it significant? A: A coronal plane fracture of the femoral condyle (usually Lateral). It is significant because:

1. Radiology: It is often invisible on AP X-ray (obscured by intact anterior bone) and subtle on Lateral. CT is mandatory.
2. Stability: It is unstable in flexion/extension.
3. Fixation: Standard lateral screws miss it. It requires Anterior-Posterior screws.

Q2: Describe the deforming forces on a distal femur fracture. A:

• Gastrocnemius: Flexes the distal fragment (Recurvatum/Extension).
• Adductors: Pull the shaft into Varus (and Adduction).
• Quadriceps/Hamstrings: Shortening.

Q3: Classify Periprosthetic distal femur fractures. A: Rorabeck Classification.

• Type I: Undisplaced. (Conservative/Brace).
• Type II: Displaced but Prosthesis Stable/Fixed. (Fixation - Nail/Plate).
• Type III: Displaced and Prosthesis Loose. (Revision Arthroplasty).

(End of Topic)