Pfn
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PFN -nailing
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PFN proximal femoral nailing technique indications complications orthopedics
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Proximal Femoral Nail (PFN) - Nailing
The PFN is a cephalomedullary intramedullary (IM) nail designed for fixation of proximal femoral fractures. It is inserted antegrade through the greater trochanter and secured into the femoral head-neck fragment with one or two proximal screws.
Indications
Standard (short) PFN:
- Pertrochanteric fractures
- Intertrochanteric fractures (all types; mandatory for unstable fractures)
- Reverse oblique fractures (31-A3)
- Comminuted fractures with loss of medial support
- Fractures without an intact lateral femoral cortex (lateral wall <20.5 mm)
- Subtrochanteric extension
- High subtrochanteric fractures
Long PFN:
- Low and extended subtrochanteric fractures
- Ipsilateral trochanteric + femoral shaft fractures
- Combination trochanteric area/shaft fractures
- Pathological fractures
Why PFN over DHS (Dynamic Hip Screw)?
- Less collapse than SHS plate devices due to the IM buttress effect
- Lower risk of lateral wall fracture
- Better biomechanics for unstable fracture patterns
- Less blood loss and shorter operative time in some series
(Campbell's Operative Orthopaedics 15th Ed., block31)
Classification of Fractures (AO/OTA)
| Type | Description | Stability |
|---|---|---|
| 31-A1 | Single fracture line, no comminution | Stable |
| 31-A2 | Comminuted, separate lesser trochanter fragment | Unstable |
| 31-A3 | Reverse oblique, transverse, or subtrochanteric extension | Very unstable |
PFN/cephalomedullary nail is the implant of choice for A2 and A3 fractures.
Implant Design (Classic AO PFN)
| Component | Detail |
|---|---|
| Nail diameter | Proximal 17 mm; distal 10/11/12 mm |
| CCD angle | 125°, 130°, or 135° |
| Femoral neck screw | 11.0 mm, self-tapping, 80-120 mm |
| Anti-rotation hip pin | 6.5 mm, self-tapping, 55-100 mm |
| ML angle | Anatomical 6° |
| Distal locking bolt | 4.9 mm |
Patient Positioning
- Supine on a fracture table with traction applied
- Affected limb in slight internal rotation (10-15°) and traction
- Hip in 20-30 degrees of flexion
- Fluoroscopy placed contralateral side or between the legs
- Closed reduction confirmed in AP and lateral views - check for:
- Varus deformity
- Posterior sag
- Excessive internal rotation (especially when greater trochanter is detached from distal segment)
Surgical Technique (Step-by-Step)
Entry Point
- Incision at or just proximal to the greater trochanteric tip
- Entry point: tip of greater trochanter (for standard PFN) or slightly medial to the piriformis fossa (for piriformis entry nails)
- Entry in line with the IM canal in both AP and lateral views
Nail Insertion
- Insert ball-tipped guide pin down the femoral canal to the physeal scar; measure for nail length
- Ream sequentially to 1.5 mm larger than nail diameter (typically 10-mm nail → ream to 11.5 mm)
- If anterior bow of femur is significant, ream 2 mm over nail diameter
- Assemble nail and insert with guide facing anteriorly to use the bow of the nail
- Rotate guide laterally after nail is ~halfway down the canal
- Monitor with lateral fluoroscopy throughout to avoid anterior cortical perforation
- Evaluate anteversion - nail, guide, and femoral head/neck must all be aligned on lateral view
Nail Angle Selection
- Prefer 130° nail as a default
- Nails with CCD angle less than the native neck-shaft angle (NSA) → risk of varus malreduction
- Measure contralateral hip NSA fluoroscopically for reference
Proximal Screw Placement
- Small lateral incision through skin and fascia
- Drill sleeve placed on lateral femoral cortex
- Guide pin advanced to within 5 mm of subchondral bone in the center-center position of the femoral head (confirmed on both AP and lateral)
- Measure lag screw length
- Ream for lag screw; tap in good bone quality
- Insert lag screw - compress as per manufacturer instructions
For InterTAN (twin-screw design):
- Place derotation bar first inferior to guide pin
- Then place compression screw after lag screw
- Relax traction before final compression
Distal Locking
- Insert 1 or 2 distal screws for dynamic or static locking
- Short nails: distal interlocking is optional for standard oblique fractures
- Long nails: distal locking required
Tip-Apex Distance (TAD) - Critical Concept
TAD = distance (AP view) + distance (lateral view) from tip of lag screw to apex of femoral head
- TAD < 25 mm → associated with the lowest rate of screw cut-out
- TAD > 25 mm → significantly increased cut-out risk
- Note: TAD may not apply equally to helical blade designs - medial blade migration reported even with TAD <20 mm
- Helical blades have higher fixation failure (OR 1.88) vs standard lag screws
(Campbell's Operative Orthopaedics 15th Ed., p.3451)
Complications
| Complication | Details |
|---|---|
| Screw cut-out | Most common failure; prevented by TAD <25 mm, center-center placement |
| Anterior cortical perforation | Due to nail-femur bow mismatch; risk increased with posterior entry point; use long nail cautiously |
| Varus malreduction | Associated with nail CCD < native NSA; check contralateral hip |
| Excessive internal rotation | Common when GT not attached to distal fragment; careful fluoroscopic monitoring required |
| Lateral wall fracture | If lateral wall <20.5 mm, do not use SHS; use IM nail |
| Medial screw migration | More common with helical blade than with lag screw |
| Intraoperative fracture extension | Especially in narrow canals; ream adequately, do not hammer forcefully |
| Non-union | Uncommon; risk rises with malreduction |
| Limb shortening | Less with IM nail than with SHS device |
PFN vs. PFNA (Antirotation)
| Feature | PFN (classic) | PFNA |
|---|---|---|
| Proximal fixation | 2 screws (lag screw + hip pin) | Single helical blade |
| Rotational stability | Two-screw anti-rotation | Blade compacts cancellous bone |
| Osteoporotic bone | Moderate | Better (blade compaction) |
| Current use | Being replaced by PFNA | Preferred modern design |
The PFNA replaced the classic PFN; the blade achieves rotational and angular stability through a single element by compacting cancellous bone, which is especially advantageous in osteoporotic bone.
Short vs. Long Nail
| Short PFN | Long PFN | |
|---|---|---|
| Indications | Standard/stable IT fractures | Reverse oblique, subtrochanteric, pathological, shaft involvement |
| Distal locking | Optional | Required |
| Risk | Less anterior perforation risk | Higher perforation risk (bow mismatch) |
Key Pearls
- Reduce before you nail - nail does not reduce the fracture
- Nail with guide anteriorly first, rotate laterally after halfway insertion
- Use a 10 mm nail in most intertrochanteric fractures; larger diameter does not improve outcomes and may increase anterior perforation risk
- Always confirm center-center position on both AP and lateral before inserting lag screw
- Relax traction before final compression to allow fracture fragments to seat
- If nail does not advance easily → ream more; do not hammer aggressively (risk of fracture extension)
- Learning curve is significant; meticulous instrument use is essential as all steps are cannulated
(Sources: Campbell's Operative Orthopaedics 15th Ed. 2026, block31; Miller's Review of Orthopaedics 9th Ed., block6; AO Foundation PFNA guidelines)
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