Malunion, Delayed Union and Nonunion

Weber-Cech Classification - Based on vascularity and callus formation

Vascular (Hypertrophic) Nonunions:

Avascular (Atrophic) Nonunions:

This classification is the foundation of treatment.

Non-Union Scoring System (NUSS) - Predicts treatment difficulty

Scores over 25 are associated with complex management and higher failure rates.

Scoring Components:

Higher scores correlate with increased surgical complexity and risk of failure.

Paley Classification (Malunion) - Based on deformity analysis using CORA

Level:

• Articular (intra-articular malunion)
• Metaphyseal
• Diaphyseal

Plane:

• Uniplanar (varus/valgus OR sagittal only)
• Biplanar (oblique - combined coronal and sagittal)
• Multiplanar (includes rotational component)

Complexity:

• Simple: Single CORA, no translation
• Complex: Multiple CORAs, translation, rotational, or associated infection

CORA analysis guides osteotomy planning.

FDA Definition of Nonunion:

• Minimum of 9 months since injury
• No visible progressive signs of healing for 3 consecutive months
• Will not heal without intervention

Delayed Union:

• Fracture has not healed within expected timeframe (typically 3-6 months)
• BUT shows continued signs of healing potential

The distinction is practical for treatment planning.

Limited role for established nonunion (over 9 months):

• LIPUS (Low-Intensity Pulsed Ultrasound): Evidence is conflicting. The TRUST trial (BMJ 2016) showed no benefit in fresh tibial fractures. Weak evidence for established nonunions
• Electrical stimulation: Capacitive coupling or pulsed electromagnetic fields. Weak evidence
• Metabolic optimisation: Vitamin D replacement, smoking cessation, protein supplementation

Conservative management is primarily adjunctive.

Indication: Aseptic hypertrophic femoral or tibial shaft nonunions

Mechanism:

• Reaming deposits morselised autograft (biological effect)
• Larger nail increases bending and torsional stiffness (mechanical effect)

Success Rate: Over 90% for femur, approximately 85% for tibia

Technique:

1. Remove existing nail
2. Identify nonunion site
3. Over-ream canal to 1-2mm larger than previous reamer
4. Insert nail 1-2mm larger diameter than previous
5. Static or dynamic locking based on stability
6. Consider Poller (blocking) screws in wide canals

This is the gold standard for hypertrophic shaft nonunions.

Indication: Atrophic nonunions, metaphyseal locations, or forearm/humerus where nailing less ideal

Judet Decortication Technique:

1. Wide exposure of nonunion site
2. Use osteotome to lift shingles of cortical bone (decortication)
3. This creates a bleeding vascular bed
4. Apply compression plate (LCP/DCP)
5. Pack iliac crest autograft around nonunion site

Graft Options:

• Iliac crest autograft (gold standard - has all 3 properties)
• RIA (Reamer-Irrigator-Aspirator) - lower morbidity than ICBG
• Allograft (scaffold only)
• BMP-2 (osteoinduction only - expensive)

Autograft remains the gold standard.

Indication: Large bone defects (over 3-4cm) or infected nonunions requiring resection

Stage 1 (Debridement and Spacer):

1. Radical debridement of all dead bone and infected tissue
2. Insert PMMA cement spacer (with antibiotic if infected)
3. Stabilise with external fixator or plate to maintain length
4. Allow induced membrane to form over 6-8 weeks

Stage 2 (Grafting - 6-8 weeks later):

1. Open membrane carefully (preserve it)
2. Remove cement spacer
3. Pack defect with cancellous autograft (RIA or iliac crest) inside the biological chamber
4. Close membrane over graft
5. Convert to internal fixation if external fixator was used

This technique is the standard for segmental defects.

Indication: Infected nonunions, complex deformity, large defects (bone transport)

Law of Tension-Stress (Ilizarov): Gradual traction on living tissues creates stress that stimulates regeneration and active growth.

Techniques:

• Compression: Applied at nonunion site to promote healing
• Distraction osteogenesis: Applied at separate corticotomy site to restore length
• Bone transport: Moving a segment of bone to fill a defect

Advantages:

• Can treat infection, nonunion, and deformity simultaneously
• Generates new bone without graft

Disadvantages:

• Prolonged treatment (1 month per cm of regenerate)
• Pin site infections
• Patient compliance required

Frame treatment is reserved for complex cases.

Step-by-Step Technique:

Setup:

• Supine on traction table (femur) or supine on radiolucent table (tibia)
• Image intensifier positioned for AP and lateral views
• Ensure same brand nailing system available (to remove old nail)

Procedure:

1. Incision: Use previous incision over nail entry point
2. Expose nail: Identify end cap or locking screws
3. Remove hardware: Remove end cap and locking screws
4. Extract nail: Use appropriate extraction device
5. Assess canal: Pass flexible reamer to assess nonunion site
6. Over-ream: Ream to 1-2mm larger than previous reamer size
7. Collect reaming debris: This is autograft
8. Insert larger nail: 1-2mm greater diameter than previous
9. Lock nail: Static initially; may dynamise later
10. Poller screws: Consider if canal is wide or unstable

Key Points:

• Do not strip soft tissue at nonunion site
• Larger nail is critical for increased stiffness
• Blocking screws improve alignment in metaphyseal extensions

Exchange nailing is minimally invasive and highly effective.

Step-by-Step Technique:

Setup:

• Supine with arm table (upper limb) or supine/lateral (lower limb)
• Tourniquet if upper limb

Procedure:

1. Approach: Use appropriate surgical approach for bone and location
2. Expose nonunion: Full exposure of nonunion site
3. Debride: Remove fibrous tissue from between bone ends
4. Decorticate: Judet shingling technique - lift cortical shingles with osteotome
5. Reduce: Obtain anatomical reduction of bone ends
6. Apply plate: Use compression plate (LCP or DCP)
7. Compress: Use eccentric drilling or articulated tension device for axial compression
8. Harvest graft: Iliac crest or RIA for autograft
9. Apply graft: Pack graft around nonunion site
10. Close: Layered closure over drain

Technical Pearls:

• Long plate with at least 8 cortices purchase each side
• Compression screws nearest nonunion site
• Onlay graft circumferentially

This technique provides biological augmentation with mechanical stability.

CORA Analysis (Center of Rotation of Angulation):

1. Identify mechanical axis on long-leg radiographs
2. Draw proximal and distal joint orientation lines
3. Draw proximal and distal mechanical axis lines
4. Intersection point = CORA

Osteotomy Rules (Paley):

• Osteotomy at CORA: Simple angular correction, realignment is perfect
• Osteotomy away from CORA: Needs translation plus angulation

Osteotomy Types:

CORA-based planning is essential for accurate correction.

Stage 2 Technique (6-8 weeks after Stage 1):

Setup:

• Previous approach
• Autograft harvest equipment (RIA or iliac crest)
• Internal fixation if converting from external fixator

Procedure:

1. Incision: Open previous wound
2. Identify membrane: Preserve the induced membrane capsule
3. Open membrane: Make longitudinal incision in membrane
4. Remove spacer: Extract cement spacer carefully
5. Prepare bed: Light curettage of bone ends
6. Harvest graft: RIA from femur or iliac crest
7. Pack graft: Fill defect completely with morselised cancellous graft
8. Close membrane: Repair membrane over graft
9. Stabilise: Convert to internal fixation or maintain stable frame
10. Close: Layered closure

Key Points:

• Do NOT discard the membrane - it is highly vascular and secretes growth factors
• Pack graft tightly to fill all dead space
• Stable fixation is essential for graft incorporation

The membrane is the key biological component.