• PFN (Profilin) - a protein involved in actin polymerization
• PFN (Peripheral Facial Nerve) - a clinical/anatomical topic
• PFN (Proximal Femoral Nail) - an orthopedic implant
• Pfn as an abbreviation for something else entirely

Proximal Femoral Nail (PFN) - Nailing

Indications

• 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

• Low and extended subtrochanteric fractures
• Ipsilateral trochanteric + femoral shaft fractures
• Combination trochanteric area/shaft fractures
• Pathological fractures

• 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

Classification of Fractures (AO/OTA)

Implant Design (Classic AO PFN)

Patient Positioning

1. Supine on a fracture table with traction applied
2. Affected limb in slight internal rotation (10-15°) and traction
3. Hip in 20-30 degrees of flexion
4. Fluoroscopy placed contralateral side or between the legs
5. 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

1. Insert ball-tipped guide pin down the femoral canal to the physeal scar; measure for nail length
2. Ream sequentially to 1.5 mm larger than nail diameter (typically 10-mm nail → ream to 11.5 mm)
3. If anterior bow of femur is significant, ream 2 mm over nail diameter
4. Assemble nail and insert with guide facing anteriorly to use the bow of the nail
5. Rotate guide laterally after nail is ~halfway down the canal
6. Monitor with lateral fluoroscopy throughout to avoid anterior cortical perforation
7. 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

1. Small lateral incision through skin and fascia
2. Drill sleeve placed on lateral femoral cortex
3. 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)
4. Measure lag screw length
5. Ream for lag screw; tap in good bone quality
6. Insert lag screw - compress as per manufacturer instructions

• 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 < 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

Complications

PFN vs. PFNA (Antirotation)

Short vs. Long Nail

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

Neck of Femur (NOF) Fracture

Anatomy & Blood Supply

• Fractures that disrupt this retinacular supply (especially displaced fractures) risk avascular necrosis (AVN) of the femoral head
• The femoral neck is intracapsular - there is no periosteum, so healing depends on endosteal callus and is less robust

Classification

1. By Location

2. Garden Classification (Most Widely Used)

• Garden I + II = nondisplaced (stable) → internal fixation
• Garden III + IV = displaced (unstable) → arthroplasty in elderly, ORIF in young
• Interobserver reliability is low across all 4 grades; most surgeons use the simplified displaced vs. nondisplaced dichotomy
• Garden III vs. IV differentiation: in III, neck and head still in contact but trabecular patterns are misaligned; in IV, complete loss of contact but head trabeculae re-align with acetabulum
• Limitation: Garden classification does not account for sagittal plane angulation. Garden I/II fractures with ≥20 degrees of sagittal angulation (retroversion) should not be managed as stable fractures

3. Pauwels Classification

Clinical Features

• Elderly: trivial fall, often with pre-existing osteoporosis
• Young: high-energy RTA, fall from height

• Pain in groin/hip, inability to weight bear
• Shortened, externally rotated limb (in displaced fractures)
• In impacted (Garden I) fractures, patient may still be able to partially weight-bear → diagnosis can be missed

• AP pelvis and lateral hip X-ray (first line)
• MRI - gold standard for occult fractures (CT may miss non-displaced fractures)
• CT - useful for assessing posterior comminution before surgery

Treatment Decision Framework

NOF Fracture
     |
     ├── Nondisplaced (Garden I/II)
     |        └── Internal fixation (cannulated screws × 3)
     |            [young AND elderly - preserves femoral head]
     |
     └── Displaced (Garden III/IV)
              |
              ├── Young patient (physiologically <60 yrs)
              |        └── URGENT ORIF (within 6-12 hrs)
              |            [preserve femoral head]
              |
              └── Elderly patient
                       |
                       ├── Low functional demands / comorbid
                       |        └── Hemiarthroplasty
                       |
                       └── Active, independent, good bone quality
                                └── THA (Total Hip Arthroplasty)

Operative Management

A. Cannulated Screw Fixation (Internal Fixation)

1. Supine on fracture table; closed reduction using Whitman technique (traction, abduction, extension, then internal rotation)
2. Assess reduction with fluoroscopy - use Garden alignment index:
   • AP view: angle between medial femoral shaft and compressive trabeculae = 160-180 degrees (< 160° = varus; > 180° = excessive valgus)
   • Lateral view: angulation ~180°; >20° deviation = unacceptable retroversion/anteversion
   • Look for "S-shaped" or "reverse S-shaped" curves of femoral neck concavity meeting femoral head convexity - useful intraoperative alignment check
3. Three partially threaded cancellous screws (6.5, 7.0, or 7.3 mm) in inverted triangle configuration
   • One inferior screw along the calcar
   • Two superior screws (anterosuperior and posterosuperior)
   • Screws should abut cortical bone inferiorly and posteriorly to resist displacement
   • Starting points must be above the lesser trochanter (distal starts → increased peri-implant subtrochanteric fracture risk)
   • Guide pins advanced just short of articular surface; subtract 5 mm for screw length
4. Fourth screw in diamond configuration may be used for significant posterior comminution - use extreme care (risk of extraosseous placement posteriorly)

B. Femoral Neck System (FNS) and Fixed-Angle Devices

• The FNS (Synthes) is a newer fixed-angle implant showing decreased AVN rates, reduced shortening, and better functional outcomes vs. cannulated screws
• Biomechanically equivalent to dynamic hip screw; superior to multiple cannulated screws
• Proximal femoral locking plates reserved for fractures with significant posterior comminution
• Trochanteric lag screw + medial buttress plate for high Pauwels angle fractures (reduces shear)

C. Sliding Hip Screw (SHS/DHS)

• May be used for femoral neck fractures but carries a higher AVN risk than cannulated screws
• Better suited to basicervical fractures (which are more extracapsular in behaviour)

D. Hemiarthroplasty

• Displaced fractures (Garden III/IV) in elderly with low functional demands
• Patients unable to comply with dislocation precautions (dementia, Parkinson's disease)
• Cemented femoral component is recommended for femoral neck fractures
• Unipolar and bipolar prostheses have similar functional results

E. Total Hip Arthroplasty (THA)

• Displaced fractures in active, independent elderly patients - provides best functional outcomes
• Pre-existing hip arthritis (OA or RA) - THA preferred over hemiarthroplasty
• Higher dislocation rate than hemiarthroplasty - must counsel patients appropriately

Timing of Surgery

• Surgery within 48 hours reduces mortality
• Young patients with displaced fractures: treat as an orthopaedic emergency (within 6-12 hours if possible) - every hour of delay increases AVN risk
• Preoperative echocardiogram should NOT delay surgery in most cases
• Operate despite recent antiplatelet drug use
• Tranexamic acid (TXA) should be given to reduce blood loss and transfusion requirements

Complications

Osteonecrosis and Non-union

• Osteonecrosis is an ongoing problem even after nondisplaced fractures
• In young patients with nondisplaced fractures, capsulotomy is considered (routine capsulotomy is controversial; most effective when capsule is not torn and intracapsular tamponade may be contributing)
• Valgus intertrochanteric osteotomy is an option for femoral neck non-union/malunion in young patients
• In elderly: non-union and AVN are treated with THA

Special Considerations

• Located at the base of the neck; partly intracapsular, partly extracapsular
• Behave biomechanically more like intertrochanteric fractures
• Higher failure rate with cephalomedullary nailing (screw cut-out even with TAD <22 mm reported)
• Management debated; options include SHS, IM nail with derotational screw, or arthroplasty in the elderly

• Typically high-energy mechanisms
• Associated injuries common
• Every effort made to preserve the femoral head: urgent ORIF within 6-12 hours
• Failure of fixation → revision ORIF or valgus osteotomy (not immediately to arthroplasty)

• Consider underlying malignancy, Paget's disease, metabolic bone disease
• Long PFN with cephalomedullary fixation for metastatic disease; arthroplasty for lytic lesions in femoral head/neck