Distal femur fractures and Nonunion

Courtesy: Prof Nabil Ebraheim, University of Toledo, Ohio, USA

DELAYED UNIONS OR NON UNIONS OF THE DISTAL FEMUR

Introduction

• Failure rate: 20–30%
• Key: Mechanical stability + autologous bone graft
• may require dual-plate fixation or intramedullary nail-plate combinations
• Bone graft substitutes/biologics: further research needed

Anatomy

• Distal femur: ~15 cm segment
• metadiaphyseal junction to the articular surface
• Trapezoidal shape in axial plane
• Key landmarks: condyles, epicondyles

Definition

• Nonunion (FDA): 9 months post-injury, no healing in last 3 months
• Delayed union: prolonged healing, often >6 months

Epidemiology

• Nonunion rate: 0–34%
• Bimodal age distribution
• Higher in open, comminuted, unstable fractures

Risk Factors

• Obesity, diabetes, open fractures
• Medial bone loss, comminution
• Unstable fixation

Pathophysiology

Weber & Cech classification:

• Hypertrophic: abundant callus, poor stability
• Oligotrophic: incomplete healing, decreases biologic response
• Atrophic: no callus, poor biologic response

Treatment Principles

• Stability + Biology
• Patient-specific approach
• Autologous bone graft = gold standard

Fixation Options

• Lateral plate
• Medial + lateral plate
• IM nailing
• Nail-plate combo
• External fixation
• Arthroplasty

Lateral Plate Fixation

• Historically standard
• Union rate up to 97%
• Failures still reported
• Lateral Plating – Studies
  -Gardner: 97% union in 31 pts
  – Bellabarba: 100% union in 20 pts
  – Wang: 5-month avg healing time

Dual Plating

• Adds medial stability
• Improves outcomes in varus collapse
• Minimally invasive options
• Dual Plating – Evidence
  -Higher union, lower complications
  – Safe vascular zone
  -Useful in atrophic non unions

Intramedullary Nailing

• Retrograde nail preferred
• Soft-tissue preservation
• Success rate: 25–100%
• Nailing – Studies
  – Wu: 100% union in 12 pts
  – Koval: 25% union in 16 pts
• Effectiveness varies with location
• Exchange nailing is more effective for diaphyseal or isthmus fractures than metaphyseal fractures.

Nail + Plate Combination

• Improved biomechanical stability
• Early weight-bearing
• Useful in osteoporotic bone,substantial medial bone loss or severe comminution

Nail + Plate – Evidence

• Attum: 100% union in 10 pts
• Liporace: early mobilization success
• Saxena: strong outcomes in elderly

External Fixation

• Reserved for infection/soft tissue loss
• Ilizarov method: effective but uncomfortable pin-site infections
• prolonged time to union
• device poorly tolerated
• External Fixation – Studies
  -Saridis: 100% union, poor tolerance
  -Cavusoglu: effective for complex fractures

Distal Femoral Replacement

• Salvage option
• Used in elderly, severe comminution
• Early mobilization possible

Bone Grafting

• Autograft = gold standard
• Allografts, BMPs as adjuncts
• Masquelet technique for large defects

 

Outcomes & Prognosis

• Risk of reoperation, infection
• Good functional recovery if treated
• Impaired QoL persists

Summary

• No gold standard
• Technique based on fracture pattern and bone quality
• Nail-plate or dual plate = good stability

 

Recommendations

• Stability + biology essential
• Use autograft
• Choose fixation based on fracture type
• Allow early mobilization